Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
FOR
SYSTEM FOR REMOTELY CONTROLLING ENERGY DISTRIBUTION
AT LOCAL SITES
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The field of the invention generally pertains to systems and methods
for
controlling energy distribution at local sites.
2. Background
[0002] Electrical utilities face particular challenges in meeting continuously
changing customer load demands. At least two related reasons exist for these
challenges. First, power demands can fluctuate substantially from day to day
or hour
to hour, making it difficult for utilities to ensure that they have enough
capacity to
meet demand. These fluctuations in energy demand may arise from ordinary
cyclic
energy usage patterns (for example peaking in~ the afternoon), or else can
result from
an unexpected change in the balance between energy supply and demand, such as
where, for example, a power generator linked to the power grid unexpectedly
goes
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down, large energy users go on or off line, or a fault occurs somewhere in the
distribution system.
[0003] A second factor contributing to the challenges faced by power utilities
is
the fact that power consumption in local areas tends to grow over time,
gradually
placing increasing burdens on electrical utilities to meet the growing demand.
Because the construction of new power plants is very costly and must comply
with a
variety of governmental regulations, it is possible for a local or even large
geographic
region to find itself without the power capacity to supply its current or
anticipated
future demand.
[0004] A major challenge for utility companies is handling peak energy
demands. This is because the energy supplied by power utilities must be
sufficient to
meet the energy demand moment by moment, and peak demands place the greatest
strain on the power distribution system. When energy demand outstrips
available
supply, disruptive events such as power blackouts, brownouts or interruptions
can
occur. Not only can such events cause substantial inconvenience to large
numbers
of people and businesses, but they can also be dangerous or life-threatening -
where, for example, the power supply for hospitals or critical home care
medical
equipment is compromised.
[0005] Historically, when power utilities serving a locality have been faced
with
a severe energy situation caused by high demand, their options have been
extremely
limited. Power utilities can, for example, request that consumers conserve
energy,
but not all consumers follow such requests and, in any event, conservation has
not
tended to provide a complete solution for energy supply problems. Power
utilities
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can attempt to satisfy peak demands by purchasing available energy from a
third
party source connected to the power grid, but such purchases, particularly at
peak
demand times, can be extremely costly as energy suppliers often demand a
premium
when demand is high. Another option is for power utilities to build additional
power
plants, but building power plants takes substantial time and investment, and
may
require approvals from state and/or federal government authorities as well as
consumer associations.
[0006] To help reduce peak power demand and thus ward off costs associated
with new power plants or premium energy purchases, various attempts have been
made to develop load management systems which control peak demand on the
power generating equipment by temporarily turning off certain customer loads
when
deemed necessary to avoid a blackout or similar power interruption. Generally,
the
types of customer loads that are regulated in this manner involve non-critical
electrical equipment such as air conditions, electric heaters, and the like.
[0007] One type of load management system,for example, uses ripple tone
injection to send coded pulses over the utility's power lines. The coded
pulses may
be applied to the utility power lines by way of an electromechanical ripple
control
transmitter, which may consist of a motor/alternator operating through
thyristor static
switches, or by way of a step-up transformer selectively connected to the
utility power
lines through a passband circuit tuned to the frequency of the coded pulse
signal. At
the customer sites, receivers interpret the coded pulses and perform desired
command functions - e.g., turning off the customer load(s).
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[0008] An example of a particular system for load management is described in
U.S. Patent 4,264,960. As set forth in that patent, a plurality of substation
injection
units, under control of a master control station, transmit pulse coded signals
on the
utility power lines. Remote receiver units positioned at customer loads
control the on
and off states of the loads in response to the signals received over the
utility power
lines from the substation injection units, by activating latchable single-pole
contacts.
Different types of loads are organized into load control groups (e.g.,
electrical hot
water heaters, air conditioner compressors, street lights, etc.). The master
control
station independently controls the various difFerent types of loads through
different
pulse control signals. Each remote receiver unit is pre-coded so that it
responds to
one and only one pulse code signal. In order to control different types of
loads (e.g.,
hot water heater and air conditioning compressor) at the same location,
separately
encoded remote receiver units at the location are required. The master control
station turns load groups on and off in order to implement a load management
strategy, as determined by a system operator.
[0009] A variety of drawbacks or limitations exist with conventional
techniques
for load management in large-scale power distribution systems. A major
drawback is
that shut-ofF commands from the power utility to the remote customer sites are
generally propagated over the same lines that carry high-voltage electricity.
Because
transformers are used to relay electrical signals across power lines, it can
be difficult
to pass data (e.g., shut-off commands or other control signals) over power
lines.
Moreover, noise or interference can prevent proper reception of shut-off
commands
or other control signals. Any inductance at the customer load can generate
large
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harmonics, which can easily match the control signal frequency, thus blocking
out
control signals or possibly causing "false alarms." A simple household device
such
as an electric oven can disrupt the reception of control signals over power
lines.
Over a large area, since all loads inject noise into the power distribution
system, the
cumulative interference or noise effect can be substantial. Thus, using power
lines to
distribute control signals can be quite problematic, because of the many
sources of
noise and interference. Sophisticated digital signal processing techniques
might be
used to filter out the noise or interference and reconstruct control signals,
but such
techniques are complicated and would generally require that a receiver be
quite
costly.
[0010] Another drawback with conventional techniques for load management
is the lack of control either at the utility or consumer level. In situations
where the
utility is forced to shut off power to one or more regions (e.g., by causing a
rolling
blackout) in order to prevent peak demand from causing a catastrophic blackout
or
damaging power generation or distribution equipment, power customers typically
have little or no control over which loads get shed. Rather, a complete shut-
down of
the customer's power usually occurs for those customers within a region
subject to a
rolling blackout. Even in those situations where the utility has pre-
configured the
customer's wiring so that certain isolated loads (usually an air conditioner
or electric
water heater) can be dynamically shed at peak power times, neither the utility
nor the
customer can easily alter which loads get shed unless the customer's wiring is
re-
configured. Where the customer loads are collectively grouped into different
load
control groups, the utility may be able to shed certain types of loads (e.g.,
all air
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conditioners) en masse, but the choice is generally made by the utility based
upon its
overall power demands and management strategy, with little or no control being
available to the customer (other than perhaps initially giving permission to
the utility
to shut down a specific load, such as an air conditioning unit, before the
utility pre-
y configures the wiring to control the specific load as part of a larger group
of similar
loads).
[0011] Another problem that remains insufficiently addressed by conventional
load management techniques is the fact that power interruptions, brownouts or
blackouts generally occur with little or no warning to power customer. In some
cases,
where unusually large demand can be forecasted, electrical utilities have been
able
to provide warnings to power customers that a blackout or power interruption
is likely
within a certain upcoming period of time - e.g., within the next several hour
period, or
next 24 or 48 hour period. However, power interruption or blackout warnings
are
typically so broad and vague in nature as to be of limited or no value to
power
customers, who are left with uncertainty as to whether or not their power will
go out
and if so, exactly when. Moreover, since power interruption or blackout
warnings are
normally broadcast by radio or television, customers who are not tuned in by
radio or
television to the broadcast stations can easily miss the warnings and not
realize that
a power interruption or blackout is imminent.
[0012] Certain power management techniques have been proposed for
controlling power consumption at a specific local site (e.g., a factory), but
such
systems are usually isolated and operate independently of the power utility.
An
example of one power management system is described, for example, in U.S.
Patent
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4,216,384. According to a representative technique described therein, the
various
main power lines of the installation or site are monitored for energy usage,
and a
control circuit selectively disconnects loads when the total energy being
drawn at the
installation or site exceeds a specified maximum. While ostensibly having the
effect
of reducing overall power consumption at the installation or site, a drawback
of these
types of power management systems is that they can be relatively complex and
costly. For example, the power management system described in U.S. Patent
4,216,384 utilizes a set of transformers to independently monitor various main
power
lines, a bank of LED-triggered Triacs to selectively engage various customer
loads,
programmable control circuitry, automatic priority realignment circuitry, and
so on.
Because of their relative cost and complexity, these types of local power
management systems are not very suitable for widespread use, particularly for
ordinary residential use or other cost-sensitive applications. Moreover, their
operation is very localized in effect, and cannot be controlled from a central
location
such as the power utility itself.
[0013] In addition to the foregoing limitations and drawbacks, conventional
power and load management strategies are limited by the available circuits and
switches which are used in some applications to control actual power delivery
at local
sites. One common type of power switch, for example, for connecting and
disconnecting power sources to loads is a circuit breaker, which functions to
prevent
an excessive amount of current from being drawn from the power source or into
the
load by breaking the electrical circuit path between the source and load when
the
current limit is reached. A typical circuit breaker has a bimetal arm through
which
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travels a power signal from the source to the load. One end of the bimetal arm
is
connected to the power signal line, while the other end of the bimetal arm is
connected to an electrical conductor from which the power can be distributed
to the
load. When too much current travels through the bimetal arm, the heat from the
current causes the bimetal arm to deform or bend in a predictable manner,
which
causes the bimetal arm to break contact with the electrical conductor,
resulting in a
break between the power signal and the load. In this manner, the source and
load
are both protected from currents which exceed a certain limit.
[0014] While circuit breakers are useful for protecting against high current
levels, they are generally passive circuit elements whose response depends
entirely
upon the amount of power being drawn by the load. They typically do not
provide
active control of a power signal line. However, some resettable circuit
breakers have
been proposed, which utilize, for example, a spring-operated mechanism
allowing a
remote operator to open and close the contacts of the circuit breaker. An
example of
such a circuit breaker is disclosed in U.S. Patent 3,883,781 issued to J.
Cotton.
[0015] Other types of remotely controlled or operated circuit breakers are
described, for example, in U.S. Patent 5,381,121 to Peter et al., and U.S.
Patent
4,625,190 to Wafer et al. These circuit breakers involve rather elaborate
mechanisms that, due to their complexity, would be expensive to manufacture
and
potentially subject to mechanical wear or failure.
[0016] Besides circuit breakers, other types of circuits have been utilized in
controlling power signals. However, these other types of circuits have
drawbacks as
well. For example, solid state switches (e.g., transistors or silicon-
controlled rectifiers
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(SCRs)) can be used as switches between a power source and load, for
controlling
distribution of the power signal to the load. However, transistors and SCRs
generally
have limited power ratings and, at high current levels, can become damaged or
shorted. Moreover, transistors or SCRs with high power ratings can be
relatively
expensive.
[0017] It would therefore be advantageous to provide a load management
system that overcomes one or more of the foregoing problems, limitations or
disadvantages. It would further be advantageous to provide a load management
system that gives more flexibility to power utilities and/or consumers, that
is not
subject to the noise and interference effects caused by transmitting data over
power
lines, and does not require a relatively expensive receiver. It would also be
advantageous to provide a load management system that uses a controllable
electronic switch capable of selectively connecting or disconnecting a power
source
to a load and, in particular, a switch that is reliable, durable, and low-
cost, and that
can handle relatively high power demands, such as may be required for
residential or
commercial applications.
SUMMARY OF THE INVENTION
[0018] The invention in one aspect is generally directed to systems and
methods for managing or controlling power distribution at local sites.
[0019] In one aspect, a local energy control unit includes a set of
controllable
switches for controlling power delivery from a power supply line to individual
electrical
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loads. The energy control unit preferably causes the controllable switches to
engage
or disengage their respective electrical loads, in a configurable order, when
an
external command is received. The energy control unit can be user-configured
(e.g.,
programmed) to prioritize the order in which loads are disengaged. In a
preferred
embodiment, the controllable switches are electrically connected in series
with (e.g.,
downstream from) a set of circuit breakers, and the controllable switches are
preferably capable of selectively disengaging and re-engaging electrical loads
as
may be present, for example, at commercial or residential electrical outlets,
while
drawing little or no power when conducting.
[0020 In another aspect, an energy management system and associated
method therefore involve the use of remotely located energy control units at
various
customer sites for controlling energy distribution to customer loads. The
energy
control units each preferably comprise a set of controllable switches for
controlling
power delivery to various local electrical loads. A user may pre-configure the
energy
control unit to specify the order or priority in which electrical loads are
disengaged, in
response to commands to reduce energy consumption. A wireless command system
allows the energy control units to receive commands from a distant location,
such as
a central transmitter or a collection of geographically dispersed
transmitters. A
central station' can issue energy reduction commands or other similar messages
according to different priority levels. The energy control units respond to
the energy
reduction commands by disengaging one or more electrical loads in accordance
with
the priority level of the energy reduction command. By the collective
operation of the
local energy control units at their various remote locations, a substantial
overall
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power reduction can be realized, particularly, for example, at times of peak
power
demand.
[0021] In various embodiments, the local energy control units may be outfitted
with added features that enhance their utility. For example, in certain
embodiments,
an energy control unit may be configured with a programmable timer function,
allowing the priority by which the controllable switches are activated to
automatically
adjust based upon the particular day of the .week, time of day, and so on. The
energy control unit may also be configured with a memory to record the states
of the
various controllable switches, or other system parameters, over time. The
memory
may be triggered to record only after an event which causes one or more
electrical
loads to be disengaged.
[0022] In a preferred embodiment, a controllable electronic switch, as may be
used in various embodiments of an energy control unit having a set of
controllable
electronic switches for selectively disabling local electrical loads,
comprises a
deformable member (e.g., a bimetal member or arm) anchored at one end and in
controllable contact with an electrical conductor at the other end. An
incoming power
wire is connected to the bimetal member near the contact point with the
electrical
conductor. A heating element (such as a coil) is coupled to the bimetal
member, and
is controlled by a switch control signal. When the switch control signal is
not
asserted, the heating element is inactive, and power is delivered through the
incoming power wire across the end of the bimetal member to the electrical
conductor, from which it can be further distributed to the load. When the
switch
control signal is asserted, the heating element heats up causing the bimetal
to bend
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until the contact with the electrical conductor is broken. The electrical path
from the
incoming power wire to the electrical conductor (and hence, to the load) is
then
broken. So long as the switch control signal is asserted, the heating element
continues to keep the bimetal bent and the electrical path broken.
[0023] Further embodiments, variations and enhancements are also disclosed
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a block diagram of a power management system according to
one embodiment as disclosed herein.
[0025] FIG. 2 is a block diagram of a local energy control system as may be
used, for example, in accordance with the power management system of FIG. 1 or
other power management systems.
[0026] FIG. 3 is a diagram illustrating physical placement of certain
components utilized in one embodiment of a local energy control system.
[0027] FIG. 4 is a conceptual diagram of a bimetal-based circuit breaker as
known in the art.
[0028] FIG. 5-1 is a diagram illustrating an example of the flow of
electricity
when the circuit breaker of FIG. 4 is closed (normal operation), and FIG. 5-2
is a
diagram illustrating an example of how the bimetal of the circuit breaker
breaks the
circuit connection when an over-current situation occurs.
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[0029] FIG. 6 is a diagram of a controllable electronic switch as may be used
in various embodiments of power management systems as disclosed herein.
[0030] FIG. 7-1 is a diagram illustrating an example of the flow of
electricity
when the electronic switch of FIG. 6 is closed, and FIG. 7-2 is a diagram
illustrating
how the bimetal of the electronic switch of FIG. 6 breaks the circuit
connection in
response to assertion of a control signal.
[0031] FIG. 8 is a block diagram illustrating another embodiment of a
controllable electronic switch as may be used in various embodiments of power
management systems as disclosed herein.
[0032] FIG. 9 is a block diagram of another embodiment of a local energy
control system as may be used, for example, in various power management
systems
as disclosed herein.
[0033] FIG. 10 is a diagram illustrating various components of a local energy
control system in relationship to one another.
[0034] FIG. 11 is a state diagram illustrating the transition between various
alert stages, according to one process as disclosed herein.
[0035] FIGS. 12 and 13 are process flow diagrams illustrating various steps
involved in transitioning between different alert stages, according to two
different
embodiments as disclosed herein.
[0036] FIG. 14 is a diagram of another embodiment of a controllable electronic
switch using a wedge to break electrical contacts in a circuit path.
[0037] FIG. 15 is a diagram showing an example of how the controllable
electronic switch shown in FIG. 14 breaks an electrical connection.
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[0038] FIG. 16 is a diagram of another embodiment of a controllable electronic
switch using a wedge to break electrical contacts in a circuit path, having a
mechanical cam with multiple latching positions.
[0039] FIGS. 17-1, 17-2 and 17-3 are diagrams illustrating the controllable
electronic switch of FIG. 16 with the latch in an engaged position with
respect to the
cam.
[0040] FIGS. 18-1 through 18-8 are diagrams illustrating different latching
positions of the cam of the controllable electronic switch of FIG. 16.
[0041] FIG. 19 is a diagram of yet another embodiment of a controllable
electronic switch using a wedge to break electrical contacts in a circuit
path, having a
mechanical cam with multiple latching positions.
[0042] FIG. 20 is a diagram showing an example of how the controllable
electronic switch shown in FIG. 19 breaks an electrical connection.
[0043] FIGS. 21, 22, and 23 are simplified schematic diagrams illustrating
examples of control circuits or portions thereof that may be used with various
controllable electronic switches disclosed herein.
[0044] FIG. 24 is a diagram of one embodiment of a switch control circuit as
may be used in connection with various controllable electronic circuit
embodiments
shown or described herein.
[0045] FIG. 25 is a diagram of another embodiment of a switch control circuit
as may be used in connection with various controllable electronic circuit
embodiments as shown or described herein.
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DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0046] FIG. 1 is a block diagram illustrating an example of a power
management system 100 in which local energy control units, according to
various
embodiments as disclosed herein, may be utilized. As shown in FIG. 1, a power
utility 105 distributes power to a variety of customer loads 120 at local
sites 109, over
power lines 108. The power utility 105 is illustrated generically in FIG. 1,
and may
encompass one or more power generation stations or other power sources,
substations, transformers, power lines, and any other equipment which is
utilized in
generating and distributing power to customers, as is well known in the art.
The local
sites 109 may include industrial/commercial users (which typically draw power
in the
neighborhood of 4.16 kV to 34.5 kV) and residential or light commercial users
(which
typically draw power in the neighborhood of 120 and/or 240 Volts), although
more
generally they include any set of related electrical loads for which control
of energy
distribution is desired. Each of the customer loads 120 thus generally
comprises one
or more local electrical loads (not individually shown in FIG. 1 ).
[0047] At each local site 109, a wireless energy control unit 114 controls the
delivery of power from the power lines 108 to the customer loads 120. A
central
station 102 transmits energy control commands, via a communication unit 103
(which
preferably comprises at least a transmitter but may also include a receiver
for two-
way communication), to the local wireless energy control units 114 located at
the
various local sites 109. Each of the wireless energy control units 114 may
comprise
a communication unit 115 (preferably comprising at least a receiver but may
also
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possibly a transmitter for two-way communication) and a power control circuit
112 for,
among other things, interpreting the power control commands received by the
communication unit 115 and acting thereon. At each local site 109, as
explained
further herein, the power control circuit 112 receives the energy control
commands
via the communication unit 115 and selectively blocks power to one or more
individual electrical loads at the local site 109, by selectively engaging or
disengaging
various local power distribution lines 118 at the- local site 109.
[0048] The central station 102 may transmit energy control commands to the
local sites 109 using any suitable communication protocol or technique. The
communication may be either one-way or two-way. In a preferred embodiment, the
communication unit 103 comprises a radio frequency (RF) transmitter, and, in
such
an embodiment, the central station 102 preferably broadcasts energy control
commands over radio frequencies using available sidebands (e.g., FM sidebands)
and/or using frequency shift keying (FSK) transmission. However, other
wireless
communication techniques or protocols - for example, spread spectrum or
wideband
communication techniques or protocols - may also be used. While the central
station
102 is illustrated as a single feature in FIG. 1, it will be understood that
the
transmissions from the central station 102 may be relayed over a variety of
communication equipment and facilities, including communication substations
and
landlines.
[0049] An advantage of wireless transmission of energy control commands is
that a relatively wide area can be covered relatively economically, without
the need,
for example, for continuous wired landlines from the central station 102 to
the various
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local sites 109" or the need for transmitting data over noisy power lines
which are
generally subject to local and other sources of interference.
[0050] In a preferred embodiment, each wireless energy control unit 114
provides the customer with the ability to pre-select which electrical loads,
if any, at a
particular local site 109 should be disengaged in response to command messages
from the central station 102. This ability may be described in more detail
with
reference to FIG. 2, which is a block diagram of a local energy control system
200, as
may be utilized in connection with the power management system 100 shown in
FIG.
1 (and may be loosely correlated to the various components shown as local
sites
109). As shown in FIG. 2, the local energy control system 200 preferably
comprises
a wireless energy control unit 214 having a number of control lines 261 which
carry
signals for controlling the onloff states of controllable switches 262. The
controllable
switches 262 are selectively disconnected and re-connected in order to
effectively
shut down and re-energize various local loads which are supplied by individual
power
lines 263 split off from a main power line 208, which may bring incoming power
from
a power utility or other primary power source. The controllable switches 262
are
preferably connected in series with, and interposed between, a bank of circuit
breakers 251 (of the type, for example, as may typically be found at a local
residence
or commercial site) and the various local power loads. An example of one type
of
circuit breaker is illustrated in FIG. 4, and described in more detail later
herein. The
circuit breakers 251 generally act to prevent excessive current from being
drawn from
the incoming power line 208, thereby preventing hazardous conditions that may
result, for example, from a short circuit or other such condition at the local
site. Once
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a circuit breaker 251 has "tripped", thereby stopping power flow to its
respective local
power load, it typically may be reset by, e.g., activating a manual switch.
While a
preferred embodiment of the local energy control system 200 involves
controllable
switches 262 interposed between circuit breakers 251 and the output power
lines 263
carrying individual power signals to various local loads, it will be
appreciated that, in
other embodiments, the circuit breakers 251 may be omitted, or other
electrical
components (e.g., fuses) may be present instead of or in addition to the
circuit
breakers 251.
[0051] The wireless energy control unit 214 preferably comprises built-in
intelligence sufficient to receive commands electronically, and to disconnect
and re-
connect the controllable switches 262 in response thereto. The wireless energy
control unit 214 shown in FIG. 2 comprises a communication unit 215, which
preferably includes a receiver, and may also include a transmitter for two-way
communication. The communication unit 215 further comprises an antenna 216 for
receiving wireless commands transmitted from a remote location (e.g., the
central
station 102), the configuration and nature of the antenna 216 being determined
largely by the nature of the particular wireless communication technique,
according to
principles of antenna design well known in the field of wireless
communications. The
wireless energy control unit 214 also preferably includes a control circuit
portion
generally comprising one or more components capable of receiving the power
control
commands received via the communication unit 215, and selectively controlling
the
controllable switches 262 in response thereto. In a preferred embodiment, the
control circuit portion comprises a communication interface 235, a processor
230,
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one or more clocks or timers 232, a memory 239, a set of switch or setting
inputs
238, a display and/or indicators) 236, and a control register 237, and may
also
include the control lines 261 and controllable switches 262.
[0052] In operation, the communication interface 235 of the wireless energy
control unit 214 receives and, if desired, interprets and/or temporarily
stores
commands or other messages received from a remote transmitter via the
communication unit 215. The communication unit 215 may output data in a format
dependent upon the wireless communication technique or protocol employed and
the
level of sophistication of the receiving electronics. For example, the
communication
unit 215 may output a stream of digital data bits at various intervals when
information
is received from the remote transmission source. The communication interface
235
may interpret the data output from the communication unit 215 and may be
configured, for example, to recognize which data is valid and which messages
are
directed to the particular wireless energy control unit 214. Messages
transmitted
from the remote transmission source (e.g., central station 102) may, for
example, and
as further described herein, be addressed or encoded so that only certain
wireless
energy control units (e.g., those in a specific geographic area) react to the
commands
or messages being sent.
[0053] When information arrives via the communication unit 215 and
communication interface 235 that appears to be valid, the processor 230 may
become aware of the received information through any suitable means. For
example, the processor 230 may receive an interrupt signal from the
communication
unit 215, or may poll the communication unit 235 regularly to determine if
information
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has arrived. In some embodiments, to conserve energy, it may be advantageous
to
allow the processor 230 and other control circuitry to be placed in a "sleep"
state,
wherein the circuitry of the wireless energy control unit 214 is essentially
shut down,
except for the communication unit 215 and communication interface 235 and
other
essential circuitry, if any, by disengaging the power supply to the wireless
energy
control unit 214. The processor 230 and other control circuitry is reactivated
or
"awakened" by re-engaging the power supply, which may be carried out by
special
internal power supply management circuitry (not shown) when the communication
interface 235 detects that information has been received via the communication
unit
215, or upon some other event requiring attention (e.g., programming of
settings,
display update, periodic status check, etc.). In this manner, the wireless
energy
control unit 214 may use only minimal power when not responding to commands or
performing some other necessary activity.
[0054] When the processor 230 has been informed that transmission has been
received from the remote transmitter, the processor 230 attempts to respond to
any
commands or other messages that may have been received. The response of the
processor 230 generally may depend upon certain stored parameters and other
configuration information or programming instructions stored at the wireless
energy
control unit 214. In this regard, the memory 239 may be advantageously
comprised
of different logical andlor physical portions, including a working memory
portion 243,
a program instruction storage portion 242, and a parameter storage portion
239.
Generally, the program instruction storage portion 242 and parameter storage
portion
239 comprise non-volatile memory (such as EEPROM), while the working memory
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portion 242 comprises volatile memory (e.g., RAM). In certain embodiments, the
memory 239 may also have a backup DC power source (e.g., battery) to help
prevent
loss of stored information in case the main power source is interrupted.
[0055] The program instructions stored in the program instruction storage
portion 242, the parameters stored in the parameter storage portion 239,
and/or the
set of switch or setting inputs 238 largely dictate the response of the
wireless energy
control unit 214 to commands or other messages received from the remote
source,
collectively providing rules or logic by which the wireless energy control
unit 214
determines which controllable switches 262 to disconnect or re-connect. In a
preferred embodiment, the wireless energy control unit 214 is user-
configurable, such
that the order in which the controllable switches 262 are disengaged or re-
connected
can be determined individually for each local site 109. In one aspect, the
wireless
energy control unit 214, in certain embodiments, provides a capability for
establishing
a priority order by which the controllable switches 262 are disengaged or re-
connected. The priority order may be set by various switch or setting inputs
238
which can be manually adjusted. The switch or setting inputs 238 may take any
of
wide variety of forms. As but one example, each controllable switch 262 may be
associated with a multi-position switch (not shown) providing one of the
switch or
setting inputs 238. Each position of the multi-position switch may indicate
whether
the associated controllable switch 262 will be triggered in response to an
alert stage
of a particular level, as described in more detail hereinafter. For example,
in a
system wherein three possible alert stages exist, the multi-position switch
may have
four positions, three of which correspond to first-stage, second-stage, and
third-stage
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alert conditions, while the fourth position indicates that the associated
controllable
switch 262 will not respond to any of the three alert stages. The number of
switch
positions of the multi-position switches may be determined, at least in part,
by the
number of alert stages which are possible.
[0056] Alternatively, the response of the controllable switches 262 to various
alert stage conditions may be software-programmable, using various
button/switch
inputs (which may be provided as part of the switch or setting inputs 238) for
configuring the priority ordering of the controllable switches 262. As but one
example, a user may be permitted to cycle through a routine which addresses
each
of the controllable switches 262 in sequence, and for each controllable switch
262,
allows the user to enter the desired response to an alert stage condition. The
programming information may be displayed on, e.g., a small LCD display or
other
type of visual display (which, in FIG. 2, may generally be represented by
display/
indicators 236). The wireless energy control unit 214 may optionally also have
a set
of indicators (pictorially represented in FIG. 2 by display/indicators 236)
indicating, on
an individual basis, which of the controllable switches 262, if any, are
disengaged at
a given moment in time. Such indicators may be embodied, for example, as LEDs
or
other low-power light elements. The display/indicators 236 may also indicate
(by,
e.g., a special LED indicator, or a flashing message on a small LCD display,
and/or
an occasional audible sound) that an "early warning" message has been received
from the central station 102 indicating that a power alert is imminent.
[0057] In some embodiments, the wireless energy control unit 214 may be
configured with a programmable timer function, allowing the priority by which
the
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electrical loads are disengaged to automatically be adjusted based upon
certain
timing considerations - for example, the particular day of the week, time of
day, and
so on. Such timing may be programmed by the user in the same manner as setting
up the initial priority scheme by which the controllable switches 262 will be
disengaged upon receipt of messages requiring such from the central station
102.
The parameter storage portion 241 of the memory 239 may store timing
parameters
which cause the programmable priority of the controllable switches 262 to
change at
certain specific times. The memory 239 may be configured to record the states
of the
various controllable switches 262, or other system parameters, at various
points in
time. The memory 239 may, in certain embodiments, be triggered so as to record
information only after an event which causes one or more electrical loads to
be
disengaged, or some other event of significance.
[0058] As further illustrated in FIG. 2, a control register 237 may be
provided to
store the current "command" status for the controllable switches 262. In a
particular
embodiment, for example, each bit of the control register 237 may hold a
command
bit whose binary state ("1" or "0") indicates the on/off status of the
associated
controllable switch 262. The wireless energy control unit 214 may also be used
to
control other resources in the local area - for example, a gas line shutoff
290. The
mechanism for the gas line shutoff 290 may likewise have an associated on/off
status/command bit in the control register 237.
[0059] FIG. 3 is a diagram illustrating physical placement of certain
components utilized in one embodiment of a local energy control system. As
shown
in FIG. 3, a wireless energy control unit 370 may physically be attached to or
placed
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within a circuit box 300. The circuit box 300 may comprise a set of on/off or
reset
switches 351 for manually resetting circuit breakers (e.g., circuit breakers
251 shown
in FIG. 2) and/or for disengaging, on an individual basis, the electrical
loads
connected to particular circuit breaker. The switches 351 in FIG. 3 are shown
in
various on and off states. Wires output from the circuit breakers for
connection to the
various electrical loads may be connected via the wireless energy control unit
370
and, in particular, through the various controllable switches (e.g.,
controllable
switches 262 shown in FIG. 2) thereof. In the particular example illustrated
in FIG. 3,
the wireless energy control unit 370 is also shown with a set of manual
switches 372
for selecting which controllable switches will respond to remotely issued
power
management instructions and in which general priority. If only one power alert
stage
is used by the power management system 100, then the manual switches 372 can
serve their function with only two switch positions, the first position
indicating that the
controllable switch will not turn off (i.e., disconnect its electrical load)
when the power
alert stage is entered, and the second position indicating that it will turn
off when the
power alert stage is entered.
[0060] Qn the other hand, if the power management system 100 has a tiered
set of power alert stages, then a more sophisticated set of switch settings
may be
employed. For example, if three power alert stages are used in the power
management system 100 (not including a "black-out" stage or other alert stages
in
which the local power control circuits are not involved), then each of the
manual
switches 372 may have four positions, the first three positions indicating
which power
alert stage is required before the corresponding controllable switch will turn
off (i.e.,
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disengage its electrical load), and the fourth position indicating that the
corresponding controllable switch will not turn off in response to any of the
power
alert stages. The fourth position may be useful for managing electrical loads
which
the customer considers critical or essential and therefore does not want to be
disengaged if it can be avoided.
[0061] Light indicators (e.g., LEDs) 373 next to each of the manual switches
372 may be used to indicate whether any of the controllable switches have, in
fact,
disengaged their respective electrical loads in response to a message from the
central station causing the wireless energy control unit 370 to enter a power
alert
stage level requiring or requesting local power reduction. A display andlor
interface
371 may be used to present text messages, either pre-stored in the wireless
energy
control unit 370 or received from the central station, or, if buttons or
suitable means
are provided, to allow programming of various capabilities provided by the
wireless
energy control unit 370.
[0062] As previously indicated with respect to the embodiment shown in FIG.
2, the wireless energy control unit 370 (and hence, the controllable switches)
may be
placed either downstream or upstream from the circuit breaker switches 351,
since in
either case the wireless energy control unit 370 will be able to function so
as to
disengage the incoming power wires from the local electrical loads. In one
aspect,
the wireless energy control unit 370 provides a compact, efficient and
practical
means to regulate local power consumption, that is minimally intrusive to the
customer site . because it can be integrated with a common circuit box 300 or
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electrical box of similar size, therefore requiring minimal retrofitting of
existing
establishments.
[0063] In alternative embodiments, the wireless energy control unit 370 can be
placed in series with fuses, as opposed to or in addition to circuit breakers.
[0064] In various embodiments, the power management system 100 operates
to reduce or curtail overall customer power demand for an indefinite amount of
time
by issuing commands from a central source (i.e., the central station 102)
which cause
the power control circuits 112 at local sites 109 individually to disengage
selected
electrical loads 120. In a preferred embodiment, the central station 102
issues power
alert stage declarations based upon the amount of power demand reduction
needed
to maintain operation of the power utility 105 within tolerable limits.
According to one
example, one or more power alert stage levels are defined for the power
management system 100, and the central station 102 changes the power alert
stage
level by wirelessly broadcasting the alert level to the wireless communication
units
115 at the various local sites 109. As the consumer power demand increases to
threshold levels at which action is deemed necessary, the central station 102
broadcasts the power alert stage level appropriate to the current conditions.
As the
customer power demands decrease to more tolerable levels, the central station
102
may then broadcast power alert stage levels that indicate some or all of the
electrical
loads 120 may be re-engaged. The total customer power demand level at which
various power stage alerts are declared may be fixed at specific threshold
levels, or
at specific percentages of overall power capacity (which may fluctuate
dynamically -
e.g., day be day, hour by hour, or even more rapidly). Alternatively, the
power alert
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stage messages may be issued in response to manual commands entered by
authorized personnel associated with the power utility 105 andlor central
station 102,
thus allowing human judgment to be involved the decision, or a combination of
automatic and manual techniques may be used. Any number of power alert stage
levels may be employed, depending upon the desired complexity of the power
management system 100.
[0065] According to one example, the power management system 100 may
have four power alert stage levels - three of which cause the local sites 109
to
reduce their power consumption in response to commands received from the
central
station 102, and a fourth power alert stage level which requires additional
steps to be
taken (e.g., intentional brown out or black out of a geographical region).
FIG. 11 is a
state diagram 1100 illustrating the transition between various power alert
stages,
according to such an example. As illustrated in FIG. 11, the state diagram
1100
includes a plurality of states 1105 through 1109 corresponding to different
power
alert stage levels. When total customer power demand is in a tolerable range
(i.e.,
the total customer power demand level is below a specified first threshold
level
designated LEVEL1 ), the power management system 100 is kept in a non-alert
state
1105. When the total customer power demand level exceeds the first threshold
level
(i.e., LEVEL1 ), the power management system 100 enters a first stage alert
state
1106, whereupon the central station 102 broadcasts a wireless message to the
local
wireless communication units 115 indicating that a first stage power alert has
been
declared. In response, the power control circuits 112 at the local sites 109
selectively
disengage various local electrical loads 120, thus reducing the overall
customer
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power demand to keep the total energy usage within a tolerable level. The
power
utility 105 may measure the extent to which the power demand has dropped and
convey this information to the central station 102 (or other processing
center) for use
in future determinations of power alert stage levels. For example, the central
station
102 (or other processing center) may treat the current total power demand
level as
including the amount by which the total power demand level dropped as a result
of
issuing the power alert stage warning, because retracting the power alert
stage
warning at any point would presumably result in the re-engagement of the
previously
disengaged local electrical loads 120 and consequent increase in total power
demand. Therefore, when the total customer power level is shown in FIG. 11 as
being compared to various threshold levels, preferably the power management
system 100 takes into account the effect of the disengaged local electrical
loads 120.
[0066] So long as the total customer power demand stays above the first
demand threshold LEVEL1 but below a second demand threshold LEVEL2, the
power management system 100 stays in the first stage alert state 1106.
However, if
the total customer power demand continues to increase such that it passes the
second demand threshold LEVEL2, the power management system 100 then enters
a second stage alert state 1107, and the central station 102 wirelessly
broadcasts a
message to the wireless communication units 115 at the various local sites 109
indicating that a second stage power alert warning has been declared. On the
other
hand, however, if the total customer power demand drops back below the first
demand threshold LEVEL1, the power management system 100 returns to the non-
alert state 1105, whereupon the central station 102 wirelessly broadcasts a
message
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to the wireless communication units 115 at the various local sites 109
indicating that
the first stage power alert is no longer in affect, and that the power
management
system 100 is returning to the non-alert state 1105.
[0067] So long as the total customer power demand stays above the second
demand threshold LEVEL2 but below a third demand threshold LEVEL3, the power
management system 100 stays in the second stage alert state 1107. However, if
the
total customer power demand continues to increase such that it passes the
third
demand threshold LEVEL3, the power management system 100 then enters a third
stage alert state 1108, and the central station 102 wirelessly broadcasts a
message
to the wireless communication units 115 at the various local sites 109
indicating that
a third stage power alert warning has been declared. On the other hand, if the
total
customer power demand drops back below the second demand threshold LEVEL2,
the power management system 100 returns to the first stage alert state 1106,
whereupon the central station 102 wirelessly broadcasts a message to the
wireless
communication units 115 at the various local sites 109 indicating that the
second
stage power alert is no longer in afFect, and that the power management system
100
is returning to the first stage alert state 1106.
[0068] Similarly, so long as the total customer power demand stays above the
third demand threshold LEVEL3 but below a fourth demand threshold LEVEL4, the
power management system 100 stays in the third stage alert state 1108.
However, if
the total customer power demand continues to increase such that it passes the
fourth
demand threshold LEVEL4, the power management system 100 then enters a fourth
stage alert state 1109, whereupon additional steps are taken (e.g., regional
black out
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or brown out). No wireless commands are necessary in such a situation;
however, a
blackout or brownout warning message may, if desired, be transmitted by the
central
station 102, so that customers at the local sites 109 can obtain a warning
before a
blackout or brownout occurs. Optionally, the approximate amount of time until
the
blackout or brownout may also be transmitted by the central station 102, and
the time
until the upcoming outage event may be displayed by the local power control
circuits
112 so that the customers might take whatever steps are desired in such a
situation.
When the total customer power demand drops back below the third demand
threshold LEVEL3, the power management system 100 returns to the second stage
alert state 1107, whereupon the central station 102 wirelessly broadcasts a
message
to the wireless communication units 115 at the various local sites 109
indicating that
the third stage power alert is no longer in affect, and that the power
management
system 100 is returning to the second stage alert state 1107.
[0069] As an alternative way of achieving a similar result, a single power
usage threshold may be used, and the amount by which customer power demand
drops in response to each power alert stage level is not necessarily
considered in the
calculation of the next power alert stage level. According to this alternative
embodiment, as each power alert stage level is declared, the total customer
power
demand level is expected to drop due to the collective effect of the various
energy
control units 114 at the various local sites 109. Therefore, the same power
usage
threshold may be used for each power alert stage level while allowing the
beneficial
operation of the power management system 100. For example, the power usage
threshold may be set at 96% of total power capacity. When total customer power
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demand reaches the power usage threshold, a first stage power alert warning
message is transmitted to the wireless energy control units 114, which
disengage
some of the electrical loads 120. As a result, total customer power demand
will drop
by some amount (for example, five percent). The power usage threshold may
remain
at 96% of capacity. When total customer power demand reaches 96% again during
the first power alert stage level, the central station 102 may then transmit a
second
stage power alert warning message to the wireless energy control units 114,
thereby
causing another drop in total customer power demand. This cycle may be
repeated
for entry into the third and fourth power alert stage levels.
[0070] The process 1100 may be implemented in an automated system using,
for example, one or more computer processors to carry out, which may be
located at
the central station 102 or elsewhere, in either a centralized or distributed
architecture.
The threshold levels between the various power alert stages may be
programmable.
A hysteresis technique may be used such that when the customer power demand is
near a threshold level, the system does not switch back and forth between two
different power alert stage levels too quickly. In other words, when the
customer
power demand is increasing, the threshold level may be increased by a
hysteresis
amount, and as soon as the threshold level (plus the hysteresis amount) is
passed
and a new alert stage level entered, the threshold level may be decreased by a
hysteresis amount so that as the customer demand level decreases it needs to
drop
below the threshold level minus the hysteresis amount in order to switch back
to the
lower power alert stage level. Also, since switching to the next power alert
stage
level is expected to cause the total customer power demand to drop rather
suddenly
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(although such an effect can be mitigated by adding the drop-off amount into
the total
customer power demand level used for power alert stage calculations, as
alluded to
above), a hysteresis technique is helpful to prevent a rapid switch back to
the
previous power alert stage level as soon as the local sites 109 start shedding
their
selected electrical loads 120.
[0071] Applying the techniques illustrated in FIG. 11, a power utility 102 may
be able to control dynamically the total customer power demand, and thus
reduce
peak customer power consumption when necessary to avert a power crisis. By
providing multiple alert stage levels, such a power management technique
allows
some granularity in selecting the amount of customer power to be reduced, and
places the minimal burden necessary on the customers.
[0072] Further description will now be provided concerning various ways in
which a local power control circuit may selectively disconnect or re-connect
controllable switches in order to effectuate control of local power
consumption. This
description will focus on the embodiment of a local energy control system 200
illustrated in FIG. 2, but the principles and concepts are applicable to other
embodiments as well. Assuming a power management system in which different
power alert stages are defined, when the local energy control system 200
receives a
message to enter the next highest power alert stage, the wireless energy
control unit
214 examines the switch or setting inputs 238 and/or stored parameters 241 in
order
to determine which controllable switches 262 to disengage. In the example in
which
the switch or setting inputs 238 are established by multi-position switches
such as .
previously described (with each switch position corresponding to the power
alert
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stage at which the corresponding controllable switch 262 will respond by
shedding its
respective electrical load), the processor 230 may simply examine the position
settings of each of the multi-position switches to determine whether or not
the
corresponding controllable switch 262 should be set to an open position so as
to
disconnect its 'respective electrical load. When a message from the central
station
102 instructs the wireless energy control unit 214 to enter a first power
alert stage, for
example, the processor 230 checks the switch setting of each of the multi-
position
switches to determine whether the switch position indicates a response to the
first
power alert stage. When a message from the central station 102 instructs the
wireless energy control unit 214 to enter a second power alert stage, the
processor
230 checks the switch setting of each of the multi-position switches to
determine
whether the switch position indicates a response to either the first power
alert stage
or second power alert stage. When a message from the central station 102
instructs
the wireless energy control unit 214 to enter a third power alert stage, the
processor
230 checks the switch setting of each of the multi-position switches to
determine
whether the switch position indicates a response to either the first power
alert stage,
second power alert stage or third power alert stage. In each case, when the
processor 230 determines that a controllable switch 262 should respond to the
current power alert stage level, the processor 230 issues the appropriate
command in
the control register 237, which in turn causes the corresponding controllable
switch
262 to open and disengage its electrical load.
[0073] In an alternative embodiment, the switch or setting inputs 238 indicate
a
relative priority for disengaging the controllable switches 262 in response to
remote
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commands from a central station 102. In such an embodiment, an indeterminate
number of power alert stages may be utilized. When the first power alert stage
message (or power reduction command) is received, the controllable switch 262
with
the lowest priority is opened and its electrical load thereby disengaged. With
each
subsequent power alert stage message (or power reduction command), the next
highest priority controllable switch 262 is opened, until, at a maximum, all
of the
controllable switches 262 are opened. However, the switch or setting inputs
238 may
also indicate that certain controllable switches 262, which may correspond to,
e.g.,
critical or essential electrical devices, are to remained closed continuously
and never
opened.
[0074] Alternatively, if the wireless energy control unit 214 is connected to
the
output reading from a local power meter so that it can dynamically monitor how
much
power is being used at the local site, the wireless energy control unit 214
may be
instructed (either directly or indirectly), or pre-programmed, to reduce local
power
consumption by a specified percentage or amount. The wireless energy control
unit
214 may then make an initial determination (according to techniques described
above, for example) of which electrical loads to shed and, thus, which
controllable
switches 262 initially to open. The wireless energy control unit 214 may then
monitor
the local power usage to determine if additional controllable switches 262
need to be
opened to either reach the desired target energy usage level or maintain
energy
usage at the desired target level. The wireless energy control unit 214 may
open up
the additional controllable switches 262 in the priority that is indicated by
the switch
or setting inputs 238.
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[0075] As the level of the power alert stages is decreased, the wireless
energy
control unit 214 may close the controllable switches 262 and thereby re-engage
the
electrical loads in the reverse order in which the controllable switches 262
were
opened. The wireless energy control unit 214 may, if desired, impose a time
delay
between the re-connection of any two controllable switches 262 to reduce the
possibility of power spikes or similar undesirable effects.
[0076] FIGS. 12 and 13 are process flow diagrams illustrating various steps
involved in transitioning between different alert stages, according to two
different
embodiments as disclosed herein. While the processes in FIGS. 12 and 13 are
described below for convenience with reference to the power management system
embodiment shown in FIG. 1, it will be understood that the principles and
concepts
are applicable to other power management system embodiments as well. Turning
first to FIG. 12, a process 1200 for power management in accordance with a
first
embodiment is illustrated. In the process 1200 shown in FIG. 12, it is assumed
that
the central station 102 has already determined, based upon the criteria used
to make
such a determination, that a message is to be transmitted wirelessly to the
various
local sites 109 in order to adjust their power consumption (or, in certain
cases, for
some other purpose). Thus, in a first step 1201, the central station 102
transmits a
message (or series of messages), via its wireless communication unit 103, to
the
wireless communication units 115 at the various local sites 109.
[0077] The wireless transmission from the central station 102 may take any of
a variety of forms. For example, the wireless transmission may comprise a
broadcast
transmission intended for receipt at all of the local sites 109.
Alternatively, it may
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comprise a broadcast transmission intended for receipt at only certain
specified local
sites 109. In this regard, the local sites 109 may, if desired, be organized
into
different groups, according to any logical criteria, such as geographic
region,
residential/commercial (possibly with different sub-categories of residential
and/or
commercial), average usage, etc., or any combination thereof. Local sites 109
in a
particular group may be instructed by the central station 102 through
broadcast
messages which are specifically targeted for that group. Each group of local
sites
109 may, for example, be assigned a unique group address or group instruction
code, and each local site 109 then responds only to its unique group address
or
group instruction code. Alternatively, or in addition, each group of local
sites 109
may be assigned a unique frequency band or sub-band or a unique encoding
scheme, and each local site 109 would then have its wireless communication
unit
115 attuned to its unique frequency band or sub-band or configured to receive
and
decode messages according to its unique encoding scheme. In this manner, the
central station 102 is provided with increased flexibility of power
management,
allowing the central station 102 to command all or any group of local sites to
curtail
power consumption. As one benefit of such an arrangement, the central station
102
may command only a few groups of local sites 109 to curtail power in response
to a
power demand situation and, only if the amount of power reduced is
insufficient,
increase the scope of the power reduction request to other groups in gradual
steps
until the desired amount of power reduction is reached.
[0078] In addition to a group address or code for groups of local sites 109,
each local site 109 can also be assigned an individual address or code within
its
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group, thereby allowing each local site 109 to be individually commanded if
desired.
Also, one of the group addresses or codes (or frequency bands or sub-bands, or
encoding schemes) may be a systemwide broadcast address or code, allowing the
central station 102 to reach all of the local sites 109 through a single
command or
sequence of commands which are designated with the systemwide broadcast
address or code.
[0079] Returning now to FIG. 12, in a next step 1205, the wireless
communication units 115 at the various local sites 109 receive the message
transmitted from the central station 102. In the following step 1208, each
local site
109 decodes or otherwise recovers or re-constructs the information in the
received
message and, if the message is intended for the particular local site 109,
parses the
received message into any constituent components. If group addressing or
coding is
used, for example, the power control circuit 112 at a particular local site
109 may
obtain group address or code information (e.g., in a specific field) from the
received
message, and .may thereby determine whether the received message is intended
for
the particular local site 109 by comparing the group address or code in the
received
message with the local site's own group address or code. The local site 109
may
likewise determine whether the received message is a systemwide broadcast
message intended for all of the local sites 109 within the power management
system
100, by comparing the group address or code with a systemwide broadcast
address
or code.
[0080] Assuming the message is intended for it, the local site 109 parses the
message in order to determine the nature of the communication received from
the
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central station 102. As examples of messages that might be received, the local
site
109 may receive a message instructing it to enter the next highest stage of
power
alert, to enter the next lowest stage of power alert, to adjust a parameter,
or to take
some other action (e.g., display a power alert stage warning message). Various
other message types may also be employed. If the received message instructs
the
power control circuit 112 at the local site 109 to enter the next highest
stage of power
alert, then, in step 1236, the power control circuit 112 determines which
power
control switch or switches (such as switches 262 in FIG. 2) should be opened
and
thereby which local electrical loads 120 to shed. Examples of how this
determination
may be made are described with respect to FIGS. 2 and 3, and elsewhere herein.
In
step 1238, the desired power control switch or switches are opened and, in
step
1250, the various status indicators (e.g., LEDs) are updated. For example, an
LED
may be illuminated next to each power control switch that has been disengaged.
Other status indication means may also be used; for example, an audible sound
may
be issued by the power control circuit 112 to indicate to the customer that
one or
more electrical loads 120 have been temporarily shed.
[0081] If, on the other hand, the received message instructs the power control
circuit 112 to enter the next lowest stage of power alert, then, in step 1240
(and
assuming the power control circuit 112 is not in the non-alert stage), the
power
control circuit 112 determines which power control switch or switches should
be
closed and thereby which local electrical loads 120 to re-connect to power
lines 108.
Examples of how this determination may be made are described with respect to
FIGS. 2 and 3, and elsewhere herein. In step 1243, the desired power control
switch
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or switches are closed and again, in step 1250, the various status indicators
(e.g.,
LEDs) are updated. For example, an LED next to each power control switch that
has
been re-connected may be turned off.
[0082] If the received message neither instructs entry into the next highest
stage of power alert nor instructs entry into the next lowest stage of power
alert, then
in step 1225 the message is interpreted by the power control circuit 112 and
acted
upon. The specific action depends upon the nature of the received message. For
example, if the message is a warning that a power alert is expected, the power
control circuit 112 may display a message indicated such (along with the
amount of
time until the expected power alert, if desired) and/or make an audible noise
indicating that a message of interest has been received.
[0083] If the power control circuit 112 is actively adjusting the power
control
switches that are opened and closed by, e.g., monitoring power consumption at
the
local site 109 (via a local meter, for instance), then the process 1200 may be
modified such that a feedback loop is effectuated, wherein the power control
circuit
112 continuously determines the power control switch settings, adjusts the
power
control switch settings, and updates the status indicators. Where active
monitoring
and adjustment of local power consumption occurs, the power control circuit
112 may
open and close power control switches at different times at any given power
alert
stage. The power control circuit 112 may, in such an embodiment, be configured
so
as to limit the frequency of opening or closing power control switches, so as
to
minimize inconvenience to the local customer.
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[0084] FIG. 13 illustrates another process 1300 for power management similar
to the process 1200 illustrated in FIG. 12 but with certain modifications. In
FIG. 13,
steps 1301, 1305 and 1308 are generally analogous to steps 1201, 1205 and 1208
in
FIG. 12. Likewise, steps 1336, 1338, 1340, 1343 and 1350 are generally
analogous
to the corresponding steps illustrated in FIG. 12. However, in FIG. 13, new
steps
1330, 1332 and 1335 are added over the process 1200 shown in FIG. 12. The
added steps to the process 1300 of FIG. 13 address a situation in which entry
into
the next highest power alert stage is to be delayed for an amount of time
specified by
the central station 102. In such a situation, according to the embodiment
illustrated in
FIG. 13, when the power control circuit 112 has determined that the received
message instructs entry into the next highest power alert stage, the power
control
circuit 112 also derives from the received message an indication of whether
entry into
the next highest power alert stage is immediate or delayed and, if delayed,
the
amount of time until the power alert stage is entered. If entry into the next
highest
power alert stage is immediate, then the process 1300 moves directly to step
1336.
If entry into the next highest power alert stage is delayed, then in step 1332
the
power control circuit 112 issues a warning, which may take the form of, for
example,
illuminating a warning light, issuing an audible sound or sound pattern, or
the like.
The power control circuit 112 then waits for timeout of the delay period, as
indicated
by step 1335, before moving on to step 1336 after the delay period is over.
The
power control circuit 112 may use an internal timer or clock to measure the
delay
period to efFectuate the foregoing operation.
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[0085] FIG. 10 is a diagram illustrating various components of a local energy
control system 1012 in relationship to one another, in accordance with one
embodiment as disclosed herein, illustrating the potential use of feedback
from a
local meter 1092 for determining, at least in part, operation of the
controllable
switches 1062. As illustrated in FIG. 10, a set of switch controls 1037 are
used to
control the settings of a plurality of controllable switches 1062 which,
similar to the
controllable switches described with respect to FIGS. 2 and 3, allow selective
connection and disconnection of local electrical loads. A local power meter
1092
monitors the power drawn on the incoming power lines 1008 (or alternatively,
the
outgoing power lines 1063), and outputs a power usage measurement signal which
is
provided to an evaluator 1030 (which may be embodied as a processor operating
according to stored program instructions and various inputs). The evaluator
1030
compares the power usage measurement with a power usage target 1094 to
determine whether additional ones of the controllable switches 1062 should be
opened or closed. The power usage target 1094 is preferably set based upon
power
alert stage level 1093 of the local energy control system 1012. If the
evaluator 1030
determines that, based upon the power usage measurement, local power
consumption exceeds the power usage target 1094, then the evaluator 1030
determines which controllable switches 1062 to open or close based upon the
priority
settings 1038 which, as discussed earlier, can be set manually or programmed
via an
interface 1029. As power commands 1017 are received from a central station,
the
evaluator 1030 updates the power alert stage level 1093 and the power usage
target
1094 as required. The local energy control system 1012 thereby provides a
level of
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robust control of power consumption at a local site, and can be utilized
advantageously in a power management system such as shown in FIG. 1 to
efFectuate overall power demand reduction when required by a power utility.
[0086] FIG. 9 is a block diagram of an embodiment of a local energy control
system 900 illustrating principles that may be employed, for example, in
connection
with various power management systems as disclosed herein, and illustrating,
among
other things, a mechanism for providing power to the local energy control
system
900. As shown in FIG. 9, the local energy control system 900 comprises an
energy
controller 910 by which various controllable switches 962 may be used to
selectively
disconnect power from incoming power lines) 908 to various local loads,
graphically
represented in FIG. 9 as inductive elements 919. As previously described
herein with
respect to FIGS. 2 and 3, for example, the controllable switches 962 may be
connected in series with (e.g., interposed between) circuit breakers 951 (or
other
similar electrical devices) and the various local loads. A decoupler 911 is
preferably
used to allow power to be supplied from the incoming power lines) 908 to the
energy
controller 910. In a preferred embodiment, the decoupler 911 comprises a
capacitor
(possibly in combination with other circuit elements), although in alternative
embodiments the decoupler 911 may comprise a transformer and, if appropriate,
supporting circuit elements.
[0087] In alternative embodiments, power may be supplied to the energy
controller 910 indirectly, such as from an output of one of the circuit
breakers 951
(preferably one that does not have a controllable switch 962 and therefore
cannot be
disconnected).
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[0088] The nature of the power signal on the incoming power lines) 908 (or
more generally, power lines 108 in FIG. 1 ) depends in part on the type of
user. Large
industrial consumers (e.g., railroads) might accept power directly at voltage
levels of
23 to 138 kV, and typically step down the voltages further. Smaller industrial
or
commercial consumers typically accept power at voltage levels of 4.16 to 34.5
kV.
Residential consumers or light commercial users normally receive power from
local
distribution transformers at nominal voltage levels of 120 and/or 240 Volts.
Power
received by residential consumers or light commercial users is typically
single-phase,
alternating current (AC) in nature, with a nominal frequency of about 60
Hertz. The
illustrative values described above are typical in the United States, but may
vary in
other parts of the world.
[0089] Certain preferred controllable electronic switches as may be used at
local sites in connection with various power management systems as disclosed
herein, and in particular various local energy control units, will now be
described.
First, however, is presented a comparison of preferred controllable electronic
switches with conventional electrical components and, in particular, bi-metal
based
circuit breakers.
[0090] FIG. 4 is a conceptual diagram of a bimetal-based circuit breaker 400
as known in the art. As illustrated in FIG. 4, the circuit breaker 400
comprises a
bimetal arm 401 which is formed of two metallic layers 402, 403. The bimetal
arm
401 is anchored at one end 406, and connects at that end 406 to an incoming
power
signal line 415. At its other end 407, the bimetal arm 401 resides in
electrical contact
with an electrical conductor 420. The electrical conductor 420 may be
connected to a
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load (not shown) and, in normal operation (i.e., normal current flow), power
from the
power signal line 415 is conducted through the bimetal arm 401 and the
electrical
conductor 420 to the load.
[0091] The metallic substances of the different metallic layers 402, 403 of
the
bimetal arm 401 are selected to have different thermal properties such that
they heat
at different rates. In particular, the metallic substance of the lower
metallic layer 402
heats faster than the metallic substance of the upper metallic layer 403. When
the
amount of current traveling through the bimetal arm 401 is within "normal"
limits, the
amount of heating caused by the current passing through the bimetal arm 401
(which
has a natural resistivity) is small and the bimetal arm 401 does not deform.
However,
when the amount of current traveling through the bimetal arm 401 exceeds an
over-
current limit (which is determined largely by the relative thermal properties
of the
metallic substances used in the metallic layers 402 and 403), the lower
metallic layer
402 heats more rapidly than the upper metallic layer 403 and causes the
bimetal arm
401 to bend, thus breaking the electrical circuit path between the incoming
power
signal line 415 and the electrical conductor 420.
[0092] This operation can be illustrated by the diagrams of FIGS. 5-1 and 5-2.
FIG. 5-1 is a diagram illustrating an example of the flow of electricity when
the circuit
breaker 400 of FIG. 4 is closed (normal operation), and FIG. 5-2 is a diagram
illustrating an example of how the bimetal arm 401 of the circuit breaker 400
breaks
the circuit connection when an over-current situation occurs. As shown in FIG.
5-1, a
power signal travels through incoming power wire 415 (marked "IN") through the
bimetal arm 401 and across contacts 412, to the electrical conductor 420
(marked
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"OUT"). So long as the amount of current in the power signal is below the over-
current limit, the amount of heating caused by the current passing through the
bimetal arm 401 is small, and the bimetal arm 401 does not deform. However, as
now shown in FIG. 5-2, when the amount of current traveling through the
bimetal arm
401 exceeds the over-current limit, the current heats the bimetal arm 401, but
the
lower metallic layer 402 heats more rapidly than the upper metallic layer 403
thus
causing the bimetal arm 401 to bend. As a result, the contacts 412 gradually
separate, breaking the electrical circuit path between the incoming power
signal line
415 and the electrical conductor 420. The amount of current needed to cause
the
circuit breaker 400 to "trip" depends upon the relative thermal properties of
the two
metallic layers 402, 403 of the bimetal arm 401.
[0093] After being tripped, gradually the bimetal arm 401 of the circuit
breaker
400 will cool, until eventually the bimetal arm 401 is no longer deformed. As
this
occurs, the contacts 412 once again form an electrical connection, allowing
the
power signal to pass from the incoming power wire 415 to the electrical
conductor
420.
[0094] FIG. 6 is a diagram of a controllable electronic switch 600 as may be
used, for example, in certain embodiments of power distribution and management
systems and methods, and local energy control units, as described herein. As
shown
in FIG. 6, the controllable electronic switch 600 comprises a deformable
member 601
which may be formed in the general shape of an arm (similar to that shown in
FIG. 4)
and may be comprised of two layers 602, 603 having different thermal
properties.
Preferably, the two layers 602, 603 are metallic in nature, although any
durable
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substance that bends when heated can be used. As further shown in FIG. 6, the
deformable member 601 is preferably anchored at one end 606 to a non-
conductive
surface 615. At its other end, the deformable member 601 preferably resides in
contact with an electrical conductor 620 through contacts 612. An incoming
power
wire 625 is connected to the deformable member 601 preferably near the contact
point with the electrical conductor 620, so as to minimize any power
dissipation
caused by the current running through the deformable member 601, and also so
as
to avoid heating the deformable member 601 to any significant degree
regardless of
the current being drawn. The electrical conductor 620 may be connected to a
load
(not shown) and, in normal operation (that is, in the absence of assertion of
a switch
control signal, as explained below), power from the power signal line 625 is
conducted through the deformable member 601 and the electrical conductor 620
to
the load.
[0095] The metallic substances of the different metallic layers 602, 603 of
the
deformable member 601 are preferably selected to have different thermal
properties
such that they heat at different rates. In particular, the metallic substance
of the
lower metallic layer 602 preferably heats faster than the metallic substance
of the
upper metallic layer 603. When heat is applied to the deformable member 601,
the
faster heating of the lower metallic layer 602 as compared to the upper
metallic layer
603 causes the deformable member 601 to bend, similar to a circuit breaker
400,
thus breaking the electrical circuit path between the incoming power signal
line 625
and the electrical conductor 620.
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[0096] As further illustrated now in FIG. 6, a heating element 645 (such as a
resistive coil) is coupled (e.g., wrapped around, in the case of a resistive
coil) to the
deformable member 601. The heating element 645 is preferably controlled by a
switch control circuit 640 connected thereto by a pair of signal lines 641,
642. When
the switch control signal output from the switch control circuit 640 is not
asserted, the
heating element 645 is effectively disconnected (and thus inactive), and power
is
delivered through the incoming power wire 625 across the end 607 of the
deformable
member 601, via contacts 612, to the electrical conductor 620, from which it
can be
further distributed to the load. This operation is illustrated in FIG. 7-1.
When,
however, the switch control signal from the switch control circuit 640 is
asserted, the
heating element 645 heats up due to the effect of the current flowing through
the
heating element 645. Since the lower metallic layer 602 heats more rapidly
than the
upper metallic layer 603, the deformable member 601 starts to bend bends.
Eventually, as a result of this bending, the contacts 612 gradually separate,
breaking
the electrical circuit path between the incoming power signal line 625 and the
electrical conductor 620, as illustrated in FIG. 7-2.
[0097] So long as the switch control signal from the switch control circuit
640 is
asserted, the heating element 645 continues to keep the deformable member 601
bent and the electrical path between the incoming power wire 625 and the
electrical
conductor 620 disconnected. Once the switch control signal from the switch
control
circuit 640 is de-asserted, the deformable member 601 gradually cools, until
eventually the deformable member 601 is no longer deformed. As this occurs,
the
contacts 612 once again form an electrical connection, allowing the power
signal to
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pass from the incoming power wire 625 to the electrical conductor 620 and then
to
the load.
[0098] In one aspect, the controllable electronic switch 600 illustrated in
FIG. 6
can provide a convenient, inexpensive mechanism for controlling the
distribution of
power from a source to a load. Moreover, the controllable electronic switch
600 need
not consume any power when the deformable member 601 is in a closed position,
and only requires minimal power to cause the deformable member 601 to open.
[0099] The incoming power wire 625 may be connected to the deformable
member 601 in any of a variety of manners. The incoming power wire 625 may,
for
example, simply be welded, spliced or soldered to the moving end 607 of the
deformable member 601. Any form of attaching the incoming power wire 625 to
the
deformable member 601 will suffice so long as electricity conducts between the
incoming power wire 625 and the electrical conductor 620 when the deformable
member 601 is in a switch-closed position.
[0100] FIG. 8 is a block diagram illustrating a more general embodiment of a
controllable electronic switch 800. As illustrated in FIG. 8, the controllable
electronic
switch 800 comprises a deformable member 801 which controllably connects an
incoming power wire 825 to an electrical conductor 820. A heating element 845
is
coupled to the deformable member 801, and is controlled by a switch control
circuit
840. The deformable member 801, which may take the form of, e.g., a bimetal
member or arm, preferably allows the incoming power wire 825 to conduct a
power
signal to the electrical conductor 820 when the deformable member 801 is not
being
heated by the heating element 845, but preferably causes the connection
between
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the incoming power wire 825 to the electrical conductor 820 to be physically
broken
when then deformable member 801 is heated by the heating element 845. The
heating element 845 may comprise, e.g., a resistive coil or other resistor,
and, if a
resistive coil, may be conveniently wound around the deformable member 801 if
embodied as a bimetal member or arm.
[0101] In either of the embodiments illustrated in FIGS. 6 and 8, the
deformable member 601 or 801 need not be uniformly straight and, in fact, can
be
any shape so long as, when heated, it bends in a predictable manner so as to
break
the electrical connection between the incoming power wire 625 or 825 and the
electrical conductor 620 or 820. Moreover, although the deformable member 601
or
801 is described in a preferred embodiment as a bimetal arm having two
metallic
layers, it alternatively could be made out of any other material (metallic or
otherwise)
that bends in a predictable manner. Because no current needs to travel from
one
end of the deformable member 601 or 801 to the other end (unlike a circuit
breaker),
the deformable member 601 or 801 may, if desired, have non-conductive or
insulating portions separating the various areas of the deformable member 601
or
801 from one another. For example, a non-conductive portion (e.g., plastic)
could be
placed between the area of the deformable member 601 or 801 coupled to the
heating element 645 or 845 and either end of the deformable member 601 or 801
(e.g., either end 606 and/or 607 of the deformable member 601 in the example
of
FIG. 6). Further, the end of the deformable member 601 through which power is
conducted (e.g., end 607 in FIG. 6) need not be bimetal, but could be a
uniform
conductive material (e.g., a single metal). Alternatively, the deformable
member 601
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or 801 could have additional (i.e., more than two) layers. The primary quality
of the
deformable member 601 or 801 is that it bends or otherwise deforms
sufficiently
when heated so as to break the electrical connection of the path of the power
signal
(e.g., by separating contacts 612 in the example of FIG. 6).
[0102] The switch control signal output from the switch control circuit 640 or
840 to the heating element 645 or 845 is preferably a direct current (DC)
signal, but
could also be an alternating current (AC) signal or hybrid signal. When the
switch
control signal is not asserted, the switch control circuit 640 may simply
short the
heating element 645 or 845 (e.g., by shorting wires 641, 642 in the example of
FIG.
6), or else simply isolate the heating element 645 or 845 through a buffer or
other
isolation circuit.
(0103] While the heating elements 645 and 845 in FIGS. 6 and 8 have been
described in preferred embodiments as a resistive coil, the heating element
645 or
845 could take other forms or configurations. For example, if embodied as a
resistive
coil, the heating element 645 or 845 need not be wound around the deformable
member 601 or 801. The heating element 645 or 845 could be a different type of
resistor besides a resistive coil. However, a resistive coil is preferred as
the heating
element 645 or 845 because it provides relatively even heating over a given
area,
and is relatively simple to implement and is relatively inexpensive.
[0104] The speed of response of the deformable member 601 or 801 to the
swtich control circuit 640 or 840 may or may not be critical, depending upon
the
particular application. If the speed of response is not very critical, then
the switch
control signal can be a very low power signal. If faster response time is
desired, the
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switch control signal can be increased in power, thus causing more rapid
heating of
the heating element 645 or 845. The switch control circuit 640 or 840 may be
provided with its own power source (e.g., a battery), or else it may obtain
power from
the incoming power wire 625 or 825 or some other available source. The switch
control circuit 640 or 840 may be activated by a manual switch (not shown)
which
causes assertion of the switch control signal and, therefore, eventual opening
of the
controllable electronic switch 600 or 800, or else may be activated by a
remote
electronic signal.
[0105] FIG. 14 is a diagram of another embodiment of a controllable electronic
switch 1400 using a wedge to physically break electrical contacts in a circuit
path. As
illustrated in FIG. 14, the controllable electronic switch 1400 comprises a
generally
elongate deformable member 1401 which is formed of two layers 1402, 1403,
similar
in nature to the deformable member 601 described previously with respect to
FIG. 6.
In a preferred embodiment, the deformable member 1401 comprises a bimetal arm,
and the two layers 1402, 1403 are metallic in nature, although more generally
the two
layers 1402, 1403 may be comprised of any suitable materials having
sufficiently
different thermal properties to carry out the functions described herein. The
deformable member 1401 is preferably anchored at one end 1406 to a non-
conductive surface 1405. At its other end, the deformable member 1401 has a
wedge-shaped member 1451.
[0106] As further illustrated in FIG. 14, narrow end of the wedge-shaped
member 1451 resides in close proximity to a pair of electrical contacts 1452.
The
pair of electrical contacts 1452 reside in contact with a pair of electrical
conductors
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1420, 1425, the first electrical conductor 1425 serving as an incoming power
wire and
the second electrical conductor 1420 serving as a power delivery means to a
load
(not shown). In normal operation, power from the first electrical conductor
1425 is
conducted through the electrical contacts 1452 to the second electrical
conductor
1420 and thereby to the load. The electrical contacts 1452 are attached to a
pair of
non-conductive arms 1457, which are anchored to a stable surface 1460. A pair
of
springs 1455 or other such means applies force to the non-conductive arms 1457
and thereby maintains the electrical contacts 1452 in contact in normal
operation.
[0107] The electrical path formed across the electrical contacts 1452 may be
broken by application of a control signal to the deformable member 1401. To
this
end, a heating element 1445 (such as a resistive coil) is coupled to the
deformable
member 1401 (e.g., wrapped around the deformable member 1401, where embodied
as a resistive coil). The heating element 1445 is preferably controlled by a
switch
control circuit 1440 connected thereto by a pair of signal lines 1441, 1442.
When the
switch control signal output from the switch control circuit 1440 is not
asserted, the
heating element 1445 is effectively disconnected (and thus inactive), and
power is
delivered through the incoming power wire 1425 across the electrical contacts
1452
to the electrical conductor 1420, from which it can be further distributed to
the load.
When, however, the switch control signal from the switch control circuit 1440
is
asserted, the heating element 1445 heats up due to the effect of the current
flowing
through the heating element 1445. Similar to the deformable member 601
previously
described with respect to FIG. 6, the deformable member 1401 of controllable
electronic switch 1400 starts to bend. Eventually, as a result of this
bending, the
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wedge 1451 if forced between the electrical contacts 1452, causing the
contacts
1452 to gradually separate (with springs 1455 gradually compressing), and
breaking
the electrical circuit path between the incoming power signal line 1425 and
the
electrical conductor 1420, as illustrated in FIG. 15.
[0108] So long as the switch control signal from the switch control circuit
1440
is asserted, the heating element 1445 continues to keep the deformable member
1401 bent and the electrical path between the incoming power wire 1425 and the
electrical conductor 1420 disconnected. Once the switch control signal from
the
switch control circuit 1440 is de-asserted, the deformable member 1401
gradually
cools, until eventually the deformable member 1401 is no longer deformed. As
this
occurs, the wedge 1451 gradually retracts, causing the electrical contacts
1452 to
come together and once again form an electrical connection, which in turn
allows the
power signal to pass from the incoming power wire 1425 to the electrical
conductor
1420 and then to the load.
[0109] In one aspect, the controllable electronic switch 1400 illustrated in
FIG.
14, like the controllable electronic switch 600 of FIG. 6, can provide a
convenient,
inexpensive mechanism for controlling the distribution of power from a source
to a
load. Moreover, the controllable electronic switch 1400 need not consume any
power
when the electrical contacts 1452 are in a closed position, and only requires
minimal
power to cause the deformable member 1401 to bend and the electrical contacts
1452 to spread apart, opening the power signal circuit path.
(0110] FIG. 16 is a diagram of another embodiment of a controllable electronic
switch 1600 using a wedge-shaped member to break electrical contacts in a
circuit
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path. Many of the components shown in FIG. 16 are similar in nature to those
illustrated in FIG. 14. Thus, for example, the controllable electronic switch
1600 of
FIG. 16 comprises a generally elongate deformable member 1601 which is formed
of
two layers 1602, 1603, similar in nature to the deformable members) 601, 1401
described previously with respect to FIGS. 6 and 14, respectively. In a
preferred
embodiment, the deformable member 1601 comprises a bimetal arm, and the two
layers 1602, 1603 are metallic in nature, although more generally the two
layers
1602, 1603 may be comprised of any suitable materials having sufficiently
different
thermal properties to carry out the functions described herein. The deformable
member 1601 is preferably anchored at one end 1606 to a non-conductive surface
1605. At its other end, the deformable member 1601 has a wedge-shaped member
1651 that, as will be described in more detail below, functions as a
mechanical cam.
(0111] As further illustrated in FIG. 16, one end of the wedge-shaped member
1651 resides in close proximity to a pair of electrical contacts 1652. The
pair of
electrical contacts 1652 reside in contact with a pair of electrical
conductors 1620,
1625, the first electrical conductor 1625 serving as an incoming power wire
and the
second electrical conductor 1620 serving as a power delivery means to a load
(not
shown). In normal operation, power from the first electrical conductor 1625 is
conducted through the electrical contacts 1652 to the second electrical
conductor
1620 and thereby to the load. The electrical contacts 1652 are attached to a
pair of
non-conductive arms 1657, which are anchored to a stable surface 1660. A pair
of
springs 1655 or other such means applies force to the non-conductive arms 1657
and thereby maintains the electrical contacts 1652 in contact in normal
operation.
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[0112] Similar to the FIG. 14 embodiment, the electrical path formed across
the electrical contacts 1652 may be broken by application of a control signal
to the
deformable member 1601. To this end, a heating element 1645 (such as a
resistive
coil) is coupled to the deformable member 1601 (e.g., wrapped around the
deformable member 1601, where embodied as a resistive coil). The heating
element
1645 is preferably controlled by a switch control circuit 1640 connected
thereto by a
pair of signal lines 1641, 1642. When the switch control signal output from
the switch
control circuit 1640 is not asserted, the heating element 1645 is effectively
disconnected (and thus inactive), and power is delivered through the incoming
power
wire 1625 across the electrical contacts 1652 to the electrical conductor
1620, from
which it can be further distributed to the load. When, however, the switch
control
signal from the switch control circuit 1640 is asserted, the heating element
1645
heats up due to the effect of the current flowing through the heating element
1645,
and as a result the deformable member 1601 starts to bend. Eventually, as a
result
of this bending, the wedge 1651 if forced between the electrical contacts
1652,
causing the contacts 1652 to gradually separate (with springs 1655 gradually
compressing), and breaking the electrical circuit path between the incoming
power
signal line 1625 and the electrical conductor 1620, similar to the
illustration in FIG.
15.
[0113] Unlike the embodiment of FIG. 14, the wedge-shaped member 1651 of
the controllable electronic switch 1600 of FIG. 16 acts as a mechanical cam
with
multiple latching positions, thus alleviating the need to maintain the control
signal to
keep the circuit open. When the wedge-shaped member 1651 is latched in a first
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position, it is removed from the electrical contacts 1652, which remain
closed, and
the power signal circuit path is uninterrupted. On the other hand, when the
wedge-
shaped member 1651 is latched in a second position, it forces the electrical
contacts
1652 apart, thus interrupting the power signal circuit path. In either latched
position,
no power is required to keep the controllable electronic switch 1600 in its
current
state (open or closed). Latching of the wedge-shaped member 1651 in the
various
positions is accomplished, in this example, by way of a latching member 1680
comprising, e.g., an arm 1682 terminated in a ball 1681 that rests against the
wedge-
shaped member 1651. In the instant example, the arm 1682 of the latching
member
1680 is anchored to surface 1660, but the latching member 1680 may be anchored
to
any other available surface instead. Thus, in this example, the latching
member
1680 is adjacent to the arms 1657 supporting the electrical contacts 1652.
[0114 FIGS. 17-1, 17-2 and 17-3 are diagrams of different views illustrating
an
example of the wedge-shaped member 1651 of the controllable electronic switch
1600 of FIG. 1.6, and in particular FIGS. 17-2 and 17-3 illustrate the wedge-
shaped
member 1651 of FIG. 17-1 latched in the first position. The wedge-shaped
member
1651 in this example comprises a front wedge section 1705 (which may be
generally
broad-surfaced and sloping), a central socket 1701, and a rear wedge section
1706
(which may be tapered and sloping) defining a shallow rear socket 1708. As
best
illustrated in FIGS. 17-2 and 17-3, the ball 1681 of the latching member 1680
rests on
the front wedge section 1705 when the wedge-shaped member 1651 is latched in
the
first position (the arm 1682 is omitted from FIGS. 17-2 and 17-3 for
clarifying the
other features shown). The ball 1681 may effectively hold the wedge-shaped
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member 1651 in place when latched in the first position, although in certain
embodiments the ball 1681 may not need to contact the wedge-shaped member
1651 and would generally lie in proximity therewith.
[0115] FIGS. 18-1 through 18-8 are diagrams illustrating how the wedge-
shaped member 1651 transitions between different latching positions. FIGS. 18-
1
and 18-2 are similar to FIGS. 17-2 and 17-3, respectively, and show the wedge-
shaped member 1651 at rest in the first latched position. FIG. 18-3
illustrates what
happens as the deformable member 1601 is heated in response to the control
signal
being applied to the heating element 1645 (shown in FIG. 16). In this
situation, the
deformable member 1601 starts to bend, forcing the wedge-shaped member 1651
forward. When that occurs, the ball 1681 slides over the sloping surface of
the front
wedge section 1705, and comes to rest in the central socket 1701 of the wedge-
shaped member 1651, causing the wedge-shaped member to stabilise in the second
latched position. For comparative purposes, the first latched position is
represented
by a dotted outline 1651' of the wedge-shaped member, although the actual
dimensions of movement may be somewhat exaggerated for illustration purposes.
In
practice, movement of the wedge-shaped member 1651 by only a few hundredths of
an inch may be sufficient to change latched positions. Even after the control
signal is
de-asserted, the ball 1681 retains the wedge-shaped member 1651 in the second
latched position, by virtue of its resting firmly in the central socket 1701.
The wedge-
shaped member 1651 thereby keeps the contacts 1652 separated while it is held
in
the second latching position.
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(0116] Application of a subsequent control signal causes the wedge-shaped
member 1651 to return to the first latched position. When the subsequent
control
signal is applied, the deformable member 1601 again heats up, causing it to
bend
and the wedge-shaped member 1651 to gravitate forwards. The ball 1681 is
thereby
forced out of the central socket 1701 and onto the second wedge section 1706,
as
illustrated in FIG. 18-5. The ball 1681 slides down the tapered surface of the
second
wedge section 1706, and due to the very narrow tail end of the second wedge
section 1706 (which is preferably asymmetrically tapered) the ball 1681 slides
off the
more sharply tapered side of the second sedge section 1706 and is captured by
the
upper lip of the shallow rear socket 1708, as illustrated in FIG. 18-6. The
upper lip of
the shallow rear socket 1708 helps guide the ball 1681 along the outer side
surface
1710 of the wedge-shaped member 1651, as illustrated from a side view in FIG.
18-7
and a top view in FIG. 18-8, during which time the arm 1682 of the latching
member
1680 may be forced slightly to the side of the wedge-shaped member 1651 (or
vice
versa). As the deformable member 1601 cools, the ball 1681 slides along the
outer
side surface 1710 of the wedge-shaped member 1651 and eventually reaches the
narrow tip region of the front wedge section 1705, whereupon the arm 1682 of
the
latching member 1680 straightens out and forces the ball 1681 onto the surface
of
the front wedge section 1705, returning the wedge-shaped member 1651 to the
first
latched position as illustrated in FIGS. 18-1 and 18-2.
[0117] The above process may be repeated as desired to allow the
controllable electronic switch 1680.to open and close the electrical contacts
1652 by
having the wedge-shaped member 1651 move between the first and second latched
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positions. The control signal that is applied to cause the wedge-shaped member
1651 to move may take the form of, e.g., an impulse signal.
[0118] F.IG. 19 is a diagram of yet another embodiment of a controllable
electronic switch 1900 using a wedge-shaped member to break electrical
contacts in
a circuit path, again employing principles of a mechanical cam with multiple
latching
positions. In FIG. 19, the controllable electronic switch 1900 comprises a
generally
elongate deformable member 1901 which, as before, is formed of two layers
1902,
1903, similar in nature to, e.g., the deformable members) 601, 1401 described
previously with respect to FIGS. 6 and 14, respectively. In a preferred
embodiment,
the deformable member 1901 comprises a bimetal arm, and the two layers 1902,
1903 are metallic in nature, although more generally the two layers 1902, 1903
may
be comprised of any suitable materials having sufFiciently difFerent thermal
properties
to carry out the functions described herein. The deformable member 1901 is
preferably anchored at one end 1906 to a non-conductive surface 1905. At its
other
end, the deformable member 1901 has a wedge-shaped member 1951 that, as will
be described in more detail below, functions as a mechanical cam.
[0119] As further illustrated in FIG. 19, a pivoting arm 1980 is positioned
between the first wedge-shaped member 1951 and a pair of electrical contacts
1952.
The pair of electrical contacts 1952 reside in contact with a pair of
electrical
conductors 1920, 1925, the first electrical conductor 1925 serving as an
incoming
power wire and the second electrical conductor 1920 serving as a power
delivery
means to a load (not shown). In normal operation, power from the first
electrical
conductor 1925 is conducted through the electrical contacts 1952 to the second
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electrical conductor 1920 and thereby to the load. The electrical contacts
1952 are
attached to a pair of non-conductive arms 1957, which are anchored to a stable
surface (not shown). A pair of springs (not shown, but similar to springs 1655
in FIG.
16) or other such means applies force to the non-conductive arms 1957 and
thereby
maintains the electrical contacts 1952 in contact in normal operation.
(0120] As further illustrated in FIG. 19, the pivoting arm 1980 has a ball
1981
at one end and a second wedge-shaped member 1961 at the opposite end. The
pivoting arm 1980 may be secured to a fixed structure 1985 at, e.g., a
generally
centrally located pivoting point 1984.
(0121 ] The electrical path formed across the electrical contacts 1952 may be
broken by application of a control signal to the deformable member 1901. To
this
end, a heating element 1945 (such as a resistive coil) is coupled to the
deformable
member 1901. The heating element 1945 is preferably controlled by a switch
control
circuit 1940 connected thereto by a pair of signal lines 1941, 1942. When the
switch
control signal output from the switch control circuit 1940 is not asserted,
the heating
element 1945 is effectively disconnected (and thus inactive), and power is
delivered
through the incoming power wire 1925 across the electrical contacts 1952 to
the
electrical conductor 1920, from which it can be further distributed to the
load. When,
however, the switch control signal from the switch control circuit 1940 is
asserted, the
heating element 1945 heats up due to the effect of the current flowing through
the
heating element 1945, and as a result the deformable member 1901 starts to
bend.
Eventually, as a result of this bending, the wedge-shaped member 1951 presses
the
ball 1981 of pivoting arm 1980 such that it becomes displaced as the pivoting
arm
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1680 is forced to rotate slightly in the clockwise direction. This motion
forces the
other end of the pivoting arm 1980 to move in a clockwise direction, which in
turn
forces the second wedge-shaped member 1961 between the electrical contacts
1952. This action causes the contacts 1952 to gradually separate, and breaks
the
electrical circuit path between the incoming power signal line 1925 and the
electrical
conductor 1920, as illustrated in FIG. 20.
[0122] Similar the embodiment of FIG. 16, the wedge-shaped member 1951 of
the controllable electronic switch 1900 of FIG. 19 acts as a mechanical cam
with
multiple latching positions, thus alleviating the need to maintain the control
signal to
keep the circuit open. When the first wedge-shaped member 1951 is latched in a
first
position, it causes the second wedge-shaped member 1961 to be removed from the
electrical contacts 1952, which remain closed, and the power signal circuit
path is
uninterrupted. On the other hand, when the first wedge-shaped member 1951 is
latched in a second position, it causes the second wedge-shaped member 1961 to
force the electrical contacts 1952 apart, thus interrupting the power signal
circuit
path. In either latched position, no power is required to keep the
controllable
electronic switch 1900 in its current state (open or closed). Latching of the
wedge-
shaped member 1951 in the various positions is accomplished, in this example,
by
the pivoting arm 1980 which, similar to latching member 1680, is terminated in
a ball
1981 that rests against the wedge-shaped member 1951.
[0123] Motion of the ball 1981 with respect to the first wedge-shaped member
1951 is similar to the described with respect to the controllable electronic
switch 1600
of FIG. 16 and the illustrations in FIGS. 17-1 through 17-3 and 18-1 through
18-8.
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However, rather than the first wedge-shaped 'member 1951 itself being inserted
between the contracts 1952 to open them, the first wedge-shaped member 1951
causes the pivoting arm 1980 to swing back and forth, thereby causing the
second
wedge-shaped member 1961 to move forwards and backwards and to open and
close the electrical contacts 1952.
[0124] It should be noted that the embodiments illustrated in FIGS. 16 and 19,
and elsewhere, are merely examples and are not intended to be exhaustive nor
limiting of the concepts and principles disclosed herein. While certain cam
mechanisms have been described and illustrated, and cam or other similar
mechanism may also be used to perform similar functions. Alternative
embodiments
may include, for example, any member that is used in connection with
separating
electrical contacts (or other type of circuit connection), has at least one
stable
position and one or more unstable positions, and transitions between the
stable and
unstable positions through application of a control signal. A variety of
different
mechanical structures can be utilized in place of the wedge-shaped members)
described herein and illustrated in the drawings
[0125] FIGS. 21, 22, and 23 are simplified schematic diagrams of examples of
control circuits or portions thereof that may be used with various
controllable
electronic switches disclosed herein. In FIG. 21, a control signal generator
2100
includes a power source 2170 (e.g., battery or other DC source) connected via
a first
switch 2171 to a capacitor 2174. The capacitor 2174 is connected via a second
switch 2172 to a heating element 2145, such as a resistive coil, which is
proximate to
a deformable member 2101. The heating element 2145 and deformable member
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2101 may represent similar components which are illustrated in FIG. 16 or 19
or any
of the other controllable electronic switch embodiments described herein.
[0126] In operation, the power source 2170 maintains capacitor 2174 in a
charged state when switch 2171 is closed and switch 2172 is open. Since switch
2172 is open, the heating element 2145 is disengaged, and the deformable
member
2101 remains in its natural unheated state. To apply a control signal to the
heating
element 2145, a control circuit (not shown) opens switch 2171 and closes 2172,
as
illustrated in FIG. 22. As a result, power source 2170 is disengaged from
capacitor
2174, and the capacitor 2174 discharges into the heating element 2145. The
capacitor 2174 may be selected to be of sufficient size and rating to hold the
appropriate amount of charge to cause heating element 2145 to heat up
sufficiently
to cause the deformable member 2101, particularly if embodied as a latching
cam
mechanism (such as in FIGS. 16 and 19, for example), to be forced into the
next
latched state. Once the capacitor 2174 has been substantially discharged,
switch
2171 may be closed and switch 2172 opened, to recharge the capacitor 2174. The
switches 2171, 2172 may then again be toggled to discharge the capacitor 2174
a
second time and cause the deformable member 2101, where embodied as a latching
cam mechanism, to be forced into another latched state (or returned to its
original
latched state).
[0127] FIG. 23 applies the same principles of FIGS. 21 and 22 to a system of
controllable electronic switches. The control circuit system 2300 of FIG. 23
includes
a power source 2370 and capacitor 2374 similar to the counterparts of FIGS. 21
and
22. A first switch 2371 is analogous to switch 2171 in FIGS. 21 and 22, and is
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:! F,;:i T II " 'imdF ;..:y. Ifrn~I Ifuar n m:;;Lf fi~::IF I wt! '~,uilt
;ms:t:
Eu.:.
generally closed when charging the capacitor 2374. When it is desired to
activate the
controllable electronic switches, a control circuit 2376 opens switch 2371 and
closes
the switches 2372a, 2372b, 2372c, ... associated with the controllable
electronic
switches to be activated. Only selected ones of the switches 2372a, 2372b,
2372c,
... need be activated, according to the programming of the control circuit
2376. For
the switches 2372a, 2372b, 2372c, ... that are closed, the respective heating
elements (e.g., resistive coils) 2345a, 2345b, 2345c, ... heat up, causing
deformation
of the proximate deformable members and activation of the controllable
electronic
switches according to principles previously described herein.
[0128] FIG. 24 is a diagram of an embodiment of a switch control circuit 2401
as may be used in connection with various controllable electronic switch
embodiments shown or described herein - for example, the controllable
electronic
circuits shown in FIGS. 6, 8, or 14, or others. As illustrated in FIG. 24, the
switch
control circuit 2401 comprises an incoming AC power signal 2405 which is
coupled to
a capacitor 2408, which in turn is connected to a heating element (not shown)
via an
electronic or electro-mechanical switch 2423. A manual toggle switch or button
2420
is used to activate the electronic or electro-mechanical switch 2423, which
selectively
allows the incoming power signal 2405 to pass to the heating element 2425. The
incoming AC power signal 2405 may be, e.g., single-phase electrical power
drawn
from a power line, and the design illustrated in FIG. 24 thereby provides a
low cost,
high efficiency mechanism (with minimal current drain) for activating the
controllable
electronic switch.
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[0129] FIG. 25 is a diagram of another embodiment of a switch control circuit
2501 as may be used in connection with various controllable electronic switch
embodiments as shown or described herein - for example, the controllable
electronic
circuits shown in FIGS. 6, 8, or 14, or others. As illustrated in FIG. 25, the
switch
control circuit 2501 comprises an incoming AC power signal 2505 which is
coupled to
a capacitor 2508, which in turn is connected to a heating element (not shown)
via an
electronic 2523. A receiver 2520 receives a remote command signal via antenna
2518 and, in response thereto, opens or closes the switch 2523, which
selectively
allows the incoming power signal 2405 to pass to the heating element 2525. The
receiver 2520 may be configured to communicate using any wireless technique,
and
may, for example, be advantageously configured to receive signals transmitted
using
either frequency shift leeying (FSK) or FM sideband transmission. More
complicated
commands may be delivered via the receiver 2520, thereby allowing the switch
control circuit 2501 to be utilized as part of a circuit control system that
controls the
states numerous controllable electronic switches and allows more complex
processes and decisions to be carried out. The incoming AC power signal 2505
may
be, e.g., single-phase electrical power drawn from a power line, and the
design
illustrated in FIG. 25 thereby provides a relatively low cost, flexible, and
high
efficiency mechanism (with minimal current drain) for activating the
controllable
electronic switch.
[0130] Various embodiments of electronic switches as described herein have
the advantages of being simple, effective, controllable, reliable and
relatively
inexpensive, and are generally capable of assisting in the context of a power
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distribution or management system in order to control the distribution of
incoming
power signals (either low voltage and/or current or high voltage and/or
current) from a
power source to a load. In various embodiments, the controllable electronic
switches
are highly power efficient - for example, they need not consume any power when
the
switch is closed, and may require only minimal power to open and maintain
open.
Various controllable electronic switches as disclosed herein may be operated
remotely, such as via power control commands transmitted via a remote central
station, thus providing a flexible and convenient mechanism to control power
distribution.
[0131] In some embodiments, it may be.desirable for the central station 102 to
communicate bi-directionally with the power control circuits 112 at the
various local
sites 109. For example, the central station 102 may desire to obtain
relatively prompt
feedback on how many and/or which power control circuits 112 have responded to
a
power alert stage by shedding electrical loads 120. In such an embodiment, the
wireless communication unit 115 at the various local sites would, in addition
to
comprising a receiver, also comprise a transmitter, and the wireless
communication
unit 103 of the central station 102 would, conversely, comprise a receiver in
addition
to comprising a transmitter. Messages transmitted from the various local sites
109
may be distinguished by any of the techniques described herein or any
conventional
techniques. For example, such transmissions may be distinguished by any
combination of. different addresses, frequencies, codes, and so on.
[0132] In some embodiments, the power control circuits 112 may store
historical information regarding their response to various power alert stage
levels
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declared via the central station 102, for billing or other purposes. In the
embodiment
shown in FIG. 2, for example, the wireless energy control unit 214 may store
such
historical information in a non-volatile portion of memory 239. The historical
information may include such information as which controllable switches 262
were
disengaged in response to the declaration of a particular power alert stage
level,
and/or how much energy consumption was reduced immediately before and after as
a result of shedding the electrical loads) connected to the disengaged
controllable
switch(es). This type of information may be used by the power utility in
connection
with providing customer incentives for reducing power consumption using a
wireless
energy control unit such as described herein. The historical information may
be
transmitted upon request from the local power control circuits 112 to the
central
station or power utility 105, assuming bi-directional communication capability
exists in
the power management system 100. Alternatively, the historical information may
be
read out through a direct connection, or by transmitting the information over
the
power lines, or by some alternative technique.
[0133] While certain embodiments have been described in the text herein
andlor illustrated in the drawings, it will be understood that a variety of
changes,
modifications, additions, or substitutions may be made which take advantage of
the
principles and concepts underlying the various embodiments described and
illustrated. As but a few examples, the embodiments described herein and
illustrated
in the drawings may not be limited to a particular wireless technique or
protocol, or a
particular type of message or power command format or sequence, or a
particular
circuit configuration. Not all of the local electrical loads need to be
subject to being
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shed by the local energy control circuits described herein, nor is there any
limitation
on the types of additional electrical components (circuit breakers, fuses,
transformers, inductors, capacitors, filters, etc.) that can be used in
combination or
connection with the various embodiments of the invention. Further, rather than
using
controllable switches which disengage and re-engage electrical loads, various
embodiments may use electrical elements capable of regulating power flow on a
variable basis; however, such electrical elements generally would be expected
to be
more expensive and more power consumptive than the preferred controllable
switches disclosed herein, and may require more sophisticated control,
although
such capabilities are considered within the purview of one skilled in the art
given the
disclosure herein.
[0134] While preferred embodiments of the invention have been described
herein, many variations are possible which remain within the concept and scope
of
the invention. Such variations would become clear to one of ordinary skill in
the art
after inspection of the specification and the drawings. The invention
therefore is not
to be restricted except within the spirit and scope of any appended claims.
