Note: Descriptions are shown in the official language in which they were submitted.
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MODULE FOR CONTROLLING A SWITCH IN A HIGH VOLTAGE
ELECTRICAL SUBSTATION
TECHNICAL FIELD
The present invention relates to the field of the
supervision, control and protection of a high voltage
electrical substation.
BACKGROUND OF THE INVENTION
An electrical substation is a subsidiary station of
electricity generation, transmission and distribution
where voltage is transformed from high to low or vice-
versa using transformers. Electrical substations are
usually provided with a control module which monitors
and controls the different elements and functions of the
substation. These elements comprise disconnectors,
disconnect switches, circuit breakers and other high
voltage switch gears. As electrical substations are
operated with high voltage, the control modules have to
be protected and isolated from this high voltage so that
the components of the control module will not be damaged
by electromagnetic interferences (EMIs) or radio
frequency interferences (RFIs).
The protection of control modules is limited to voltage
surges of the order of 1000 - 1500 V. Therefore, there
is a need to provide control modules that safely operate
in environments of higher voltage surges.
SUMMARY OF THE INVENTION
According to a first broad aspect of the present
invention, there is provided a system for controlling a
high voltage switch comprising: an input/output unit
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comprising a filtering system for each of a plurality of
electrical signals passing through the input/output
unit; a logical unit comprising a memory and a first
processor, and adapted to be connected to an external
power supply; an isolation unit comprising an isolation
system for each of the plurality of electrical signals
and for a voltage signal, the input/output unit, the
isolation unit and the logical unit being electrically
connected to transmit signals received by the
input/output unit to the logical unit through the
isolation unit and to transmit externally signals
generated by the logical unit through the isolation unit
and the input/output unit; and a power unit comprising a
power board and a filter and isolation sub-unit, and
adapted to be connected to the external power supply,
the power unit being adapted to supply in power the
input/output unit and the isolation unit through the
filtering and isolation sub-unit, the high voltage
switch and the power unit being electrically connected
to the isolation unit to receive the voltage signal.
According to a second broad aspect of the present
invention, there is provided a method for operating a
control module of a high voltage switch, the method
comprising: interfacing with an external environment via
an input/output unit that filters each electrical signal
passing therethrough; analyzing incoming signals and
triggering actions as a function of the incoming signals
via a logical unit; powering the control module via an
internal power unit that is supplied by an external
power supply; and isolating the logical unit from the
power unit and the input/output unit by having all
signals coming from these units and directed to the
logical unit pass through an isolation unit.
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It should be understood that the term "switch" is to
include any type of disconnector, disconnect switch,
circuit breaker, or switch gear that serves to open and
clo'se a circuit at high voltage.
It should be understood that the term "processor" is
used to represent any circuit which can process data
and/or signals. Central processing unit (CPU),
microprocessors, and microcontrollers are examples of
processors.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present invention
will become apparent from the following detailed
description, taken in combination with the appended
drawings, in which:
Fig. 1 is a block diagram of an embodiment of the
control module comprising four units;
Fig. 2a is a graph of the voltage applied to a
disconnect switch as a function of the location of the
disconnect switch in which the rising edge of the curve
has a logarithmic shape, in accordance with an
embodiment of the present invention;
Fig. 2b is a graph of the voltage applied to a
disconnect switch as a function of the location of the
disconnect switch in which the rising edge of the curve
has an exponential shape, in accordance with an
embodiment of the present invention;
Fig. 3 is a graph of the current as a function of
location, in accordance with an embodiment of the
present invention;
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Fig. 4 illustrates an embodiment of the electrical
circuit of the input/output unit for a signal entering
the control module; and
Fig. 5 is a block diagram of an embodiment of the
control module comprising five units.
It will be noted that throughout the appended drawings,
like features are identified by like reference numerals.
DETAILED DESCRIPTION
The present control module is a system that monitors and
controls any switch present in a high voltage
environment and comprising an hydraulic, pneumatic or
electromechanical. The control module enables the
monitoring and the control of any system having motors,
valves or pieces of equipment having any kind of
movement such as a linear or rotary movement. For
example, the control module operates a real time control
of the opening and/or closing speed of a switch. The
control module controls the opening or closing speed of
the switch by varying the voltage applied to the switch.
For example, the voltage can be applied to the motor
controlling the arm of a disconnect switch or it can be
applied to a pump controlling the gas/liquid pressure of
circuit breaker.
The control module may control many aspects of the
operation including, but not limited to, internal
environmental conditions (such as temperature and
humidity levels), a switch, alarms, inputs and outputs,
internal tests, and information management.
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According to an embodiment of the control module, the
control module is protected from voltage surges of about
5000 V.
Particularly, the control module can control and adjust
parameters such as the location of the arm of a
disconnect switch or the gas/liquid pressure in a
circuit breaker. Additionally, the control module can
also control the temperature and/or humidity of the air
in the control module.
The control module can communicate with its external
environment which may include other control modules,
operators, computers, sensors, pieces of equipments,
etc.
In an embodiment, the control module comprises 4 units:
a power unit, a logical unit, an input/output unit, an
isolation unit, as illustrated in Fig. 1. The power unit
receives the power supply external to the control module
and supplies the other units in power, except the
logical unit which is supplied directly by the external
power supply. This unit also supplies in power the
switch to be controlled by the control module.
In an embodiment, the power unit comprises a power
driver and a filtering and isolation sub-unit. The power
driver is supplied by the external power supply and
supplies the switch to be controlled, the isolation and
the input/output unit in power through an isolation and
filtering sub-unit. The isolation and filtering realized
by the filtering and isolation sub-unit can be obtained
using any technique known to a person skilled in the
art.
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In an embodiment of the control module, the power unit
and the logical unit are supplied by an AC current and
the power unit generates AC currents to supply the
different elements to be controlled and the other units
of the control module.
In another embodiment, the power unit and the logical
unit are be supplied by a DC current and the power unit
generates DC currents to supply the different elements
to be controlled and the other units of the control
module. One skilled in the art would appreciate that the
control module can be supplied by an electrical
generator.
Referring to figure 1, the input/output unit represents
the interface between the control module and the
external environment. In an embodiment, the inputs
received by the input/output unit include, but are not
limited to, the signals coming from an operator, signals
coming from other control modules and/or pieces of
equipment and signals coming from sensors. For example,
the signals coming from the operator can be signals
ordering the control module to open or close the switch
or signals asking information about the control module
or the switch. For example, the signals coming from
other control modules and/or pieces of equipment can
provide information about other switches, other control
modules. They can also be alarm signals. The signals
coming from sensors indicate the performances of the
piece of equipment to be controlled. For example, the
performances can include a pressure, a position or a
current intensity.
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In an embodiment, the signals coming from the sensors go
directly to the isolation unit without passing through
the input/output unit.
The input/output unit also transmits signals directed
towards the operator or other control modules and/or
pieces of equipment of the substation. For example, the
transmitted signals can be alarm signals or signals
indicating the performances of the control module or the
switch. Furthermore, the input/output unit executes the
function of filtering the entering and exiting signals,
isolating the control module from the external medium
and protecting the control module from over-voltage.
The logical unit analyses the control signals coming
from the sensors, the command signals coming from the
operator and the signals coming from the other control
modules and/or pieces of equipment, takes decisions
whether the voltage of the switch to be controlled has
to be adjusted or not and sends signals. The signals
sent by the logical unit include communication signals
internal to the control module and signals directed to
the external environment. Signals indicating a voltage
to be applied to the switch are examples of internal
communication signals. The analysis of the signals and
the taking of decisions is performed by a processor. For
example, if a voltage has to be varied, the logical unit
communicates to the power unit through the isolation
unit the voltage that has to be applied.
In an embodiment, the logical unit can also communicate
with an external computer and the communication signal
passes through the isolation unit before reaching or
after leaving the logical unit.
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In an embodiment, the processor can store about 5
measurements per second during a long period of time.
Referring to Fig.l, the isolation unit isolates the
logical unit from the power unit and the input/output
unit. All signals entering or exiting the logical unit
pass by the isolation unit. The isolation unit ensures
the security of the logical unit against EMIs and/or
RFIs.
The isolation module which isolates the logical unit
from the remaining of the control module can be of any
kind known by a person skilled in the art. The isolation
offered by this module can be optical, mechanical and/or
galvanic.
According to an embodiment, the control module can
receive numerical or analog signals.
In an embodiment, the control module receives current
signals in the range of 4-20 mA and protects them.
In an embodiment, the control module further comprises
sensors which monitor its environmental conditions of
operation such as the temperature and the humidity.
Additionally, the control module can adjust the
temperature and/or the humidity of the cage comprising
the control module. In this case, the sensors
communicate with the logical unit through the isolation
unit. The logical unit takes decisions to whether or not
the temperature and/or the humidity have to be adjusted.
If so, the logical unit communicates the voltage to be
applied to the heating system and/or air conditioning
system and/or humidifier and/or dehumidifier and/or fan
to the power unit through the isolation unit. The
sensors can be located anywhere in the control module.
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For example, the sensors can be placed in the power unit
and, in this case, the signals sent by the sensors to
the processor passes through the isolation and filtering
subunit before reaching the isolation unit.
In an embodiment, the power unit can be supplied by a
voltage in the range of 50 to 240 V either in DC or AC
current conditions and can generate DC or AC voltages,
respectively, in the same range to control the different
switches of the substation.
In an embodiment, the operational ranges of the control
module are from 90 to 250 V under AC conditions and from
80 to 160 V under DC conditions.
The logical unit comprises a processor which analyses
the received data coming from sensors. These sensors
monitor an operating parameter and the performances of
the piece of equipment to be controlled. For example,
the operating parameter can be the position of the arm
of a disconnect switch or the gas/liquid pressure in the
case of a circuit breaker. The processor stores the data
and takes the decision to adjust or not the voltage
applied to the piece of equipment. For example, if the
piece of equipment is a disconnect switch controlled by
a motor, the logical module will decide the voltage that
has to be applied to the motor after receiving the order
to open the disconnect switch.
When the processor receives the order to vary an
operating parameter of the piece of equipment to be
controlled, the first step taken by the processor is the
reading of the operating parameter. The different values
that the operating parameter has to take in order to
achieve the variation are stored in a memory. The
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processor reads the first value to be given to the
operating parameter and transmits the voltage
corresponding to the first value of the operating
parameter to the power unit through the isolation unit.
The power unit applies the voltage to the piece of
equipment. The sensor monitoring the operating parameter
continuously transmits the value of the operating
parameter to the processor. When the processor notices
that the monitored value of the operating parameter
corresponds to the first value of the operating
parameter, the processor reads the second value to be
given to the operating parameter stored in the memory
and transmits the corresponding voltage to the power
unit which applies it to the piece of equipment. When
the monitored operating parameter corresponds to the
second value of the operating parameter, the processor
reads the third value to be given to the operating
parameter and transmits the corresponding voltage to the
power unit. These steps are repeated until the task has
been completed. These steps gives a plurality of speeds
to the opening or closing of the switch and the speed
depends on the type of switch being operated.
According to an embodiment, the location of an arm of a
motorized disconnect switch is controlled by the control
module. A sensor indicates the location of the arm to
the logical unit. The control module receives the order
to open the disconnect switch. The processor reads the
first position of be given to the arm in the database
stored in the memory and consequently transmits the
corresponding voltage to the power unit which applies it
to the motor of the disconnect switch. The motor moves
the arm of the disconnect switch. When the position
monitored by the sensor corresponds to the target
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position, the processor reads the second value to be
given to the arm and its corresponding voltage is
transmitted to the power unit which applies it to the
motor of the disconnect switch. These steps are repeated
until the disconnect switch is completely open. These
steps gives a plurality of speeds to the arm and the
speed depends on the position of the arm, whether it is
opening or closing.
Fig. 2a illustrates the voltage applied to a disconnect
switch as a function of the location of arm of the
disconnect switch. The voltage is represented in
percentage so that when a voltage of 0% is applied, the
switch does not move. The points 102 are the different
values of the location of the arm stored into the
memory, for which a corresponding voltage is also stored
in the memory. The processor reads successively the
poirits 102 and transmits the corresponding voltage to be
applied to the power unit. When the arm has reached a
position corresponding to one of the points 102, the
processor reads the next position value which
corresponds to the next point 102 and transmits its
corresponding voltage to be applied. The dashed line 104
represents the voltage curve that has to be applied to
the switch. The line 106 is the voltage curve obtained
by using the method described above.
Fig. 2a illustrates an embodiment of the closing of a
disconnect switch. A high speed is immediately set and
the arm moves quickly to reduce the duration of the arc
beirig formed between the moving contact and the fixed
contact of the switch. The speed is decreased when the
arc is cut, which occurs when the moving contact comes
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into contact with the fixed contact. The arm is stopped
when the fully closed position is reached.
Fig. 2b illustrates another curve of voltage applied to
another disconnect switch as a function of the location
of the switch. As in Fig. 2a, the voltage is represented
in percentage. The points 110 are the positions stored
into the memory. When the arm has reached one this
position, the processor reads the next one and applies
the corresponding voltage through the power unit. The
dashed line 112 represents the voltage curve that has to
be applied to the switch. The line 114 is the voltage
curve obtained by using the method described above.
Fig. 2b illustrates an embodiment of an opening of a
disconnect switch. A first speed is set until the point
when an arc forms between the moving contact and the
fixed contact. At this moment, the arm is accelerated
significantly until the arc breaks, after which the arm
is decelerated until a fully open position. A brake may
be activated to stop the arm completely.
Figs. 2a and 2b illustrate how the curve of the voltage
can be easily designed using the algorithm which
consists in varying the voltage as a function of the
position of the arm in order to vary the speed of the
arm. In Fig. 2a, the rising edge of the curve 106 has a
logarithmic shape where the rising edge of the curve 114
has an exponential shape in Fig. 2b.
It should be understood that the curve of the voltage
can have any shape by using the method described above.
It should be noted that the method above presented for
the opening or closing of the arm of a disconnect switch
is not restricted to a disconnect switch and can be
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apply to control the opening and closing speed of any
type of switch present in an electrical substation.
According to an embodiment, the processor can also have
a function of prediction of tear and wears. By only
analyzing the evolution of additional operating
parameters of the piece of equipment to be controlled,
the processor can predict damage to the piece of
equipment. An example of the additional operating
parameter can be the electric current applied to the
motor of a disconnect switch. A higher current required
to open or close switch is symptomatic of tear and
wears.
At least one additional sensor is required to monitor
the additional operating parameter. This sensor
communicates the value of the additional operating
parameter to the processor through the input/output unit
and the isolation unit. For a given value of the
operating parameter, a threshold value of the additional
operating parameter is stored in the memory. The
processor compares the value of the additional operating
parameter monitored by the additional sensor to the
threshold value stored in the memory. If the monitored
value exceeds the threshold value, the processor
predicts a damage to the piece of equipment and
activates an alarm signal indicating that maintenance or
replacement of the piece of equipment is required.
According to an embodiment, the control module controls
a disconnect switch and the processor analyses the
evolution in time of the current applied to the motor
enabling the movement of the arm of a disconnect switch.
In this case, an ampere meter monitors the current
applied to the motor and transmits the current value to
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the processor. Because of EMIs in the electrical
substation, the current applied to the motor of the arm
can varied and affect the good functioning of the
disconnect switch. The processor analyses the monitored
value of the current and takes decisions. Fig. 3
illustrates the current applied to the motor as a
function of the location of the arm. Line 154 represents
the threshold values of the current as a function of the
location of the arm. The values of line 154 are stored
into the memory of the logical unit. The processor
receives from the ampere meter the value of the current
applied to the motor and compares them to the threshold
values stored in the memory. If the monitored values
correspond to line 150, the processor compares them to
the threshold values corresponding to line 154 and
concludes that the applied current is not dangerous for
the good functioning of the disconnect switch. But if
the monitored values correspond to line 152, the
processor notices the applied current is higher than the
threshold value. In this case, the processor activates
an alarm signal.
It should also be understood that the logical unit and
the processor can control any motor, pump, valve or
component having any kind of movement.
In an embodiment of the logical unit, a heater permits
to maintain the temperature of the processor under
operating conditions. As a result, the control module
can be located inside or outside an electrical
substation. Furthermore, the control module is resistant
to extreme climatic conditions.
In an embodiment, the processor also control the
temperature and/or the humidity of the control module.
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Temperature and/or humidity sensors monitor the
temperature and/or humidity in the control module and
communicate the temperature and/or humidity to the
logical unit through the input/output unit and the
isolation unit. The processor receives the measured
temperature and/or humidity and compares them to
threshold values. If the temperature and/or humidity are
not within a tolerable range, the processor adjusts the
temperature and/or humidity by varying the voltage
applied to the heating system and/or air conditioning
system and/or humidifier and/or dehumidifier and/or fan
in order to bring the temperature and/or humidity within
the tolerable range.
The input/output unit offers a protection, an isolation
and a filtration of all of the signals passing through
it. These functions are achieved by an electrical
circuit and each signal passing through the input/output
unit has its own electrical circuit. These signals
include the control signals and the command signals. The
electrical circuit includes a protection module, a
filtration module and an electrical relay therebetween.
Fig. .4 illustrates an embodiment of the electrical
circuit of the input/output unit for a signal entering
the control module. The electrical circuit includes a
protection module 202, a filtration module 204 and an
electrical relay 206 used as an isolation module
therebetween. The protection module protects the control
module from surges and the filtration module increases
the quality of the entering signal. The electrical relay
includes a coil of actuators 208 and contacts 210.
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It should be understood that any electrical relay known
to a person skilled in the art can be used and falls
within the scope of the present embodiment.
It should also be noted that any protection module which
protects an electrical circuit from surges and any
filter for increasing the quality of an electrical
signal can be used and fall within the scope of the
present embodiment.
Fig. 5 illustrates an embodiment of the control module
which further comprises a security unit in comparison to
the control module illustrated in figure 1. The security
unit is supplied in power by the power unit. The
security unit interacts directly with the input/output
unit, the isolation unit, the logical unit and the power
unit. The security unit detects any wear or malfunction
that can occur in the other units of the control module.
Only the security unit and the isolation unit are
directly connected to the logical unit.
If a unit is deficient, the security unit communicates
the problem to the processor of the logical unit which
takes decisions. Alternatively, the security unit
activates an alarm and may also disconnect the control
module.
If the logical unit is deficient, the security unit send
an alarm signal or disconnect the control module. The
alarm signal is sent through the input/output unit.
In an embodiment, the security module comprises a
processor which analyses the functioning of the other
units and takes decision whether an alarm signal must be
sent or a problem must be reported to the logical unit.
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Alternatively, the security unit only comprises
electronic digital circuits.
In another embodiment, the security unit can be
integrated in the logical unit. In this case, the
logical unit is further connected to the input/output
unit and to the power unit. The processor of the logical
unit also detects any tear or malfunction that can occur
in the other units of the control module. The logical
unit is directly related to the power unit, the
isolation unit and the input/output unit to receive
signals indicating their respective performances. If
these signals go above or below threshold values stored
in the memory, the logical unit may send an alarm signal
and disconnect the control module.
The embodiments of the invention described above are
intended to be exemplary only. The scope of the
invention is therefore intended to be limited solely by
the scope of the appended claims.
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