Note: Descriptions are shown in the official language in which they were submitted.
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
ENERGY HISTORY BUFFER
BACKGROUND OF THE INVENTION
The present invention generally relates to methods for collecting data
for the purpose of calculating time dependent quantities, and more
particularly concerns methods of measuring demand for a resource, such as
electricity, water, natural gas, or oil. Most specifically, the present
invention
relates to methods of collecting time-synchronous measurements of the
amount of a resource used, which enables the calculation of such time
dependent quantities as demand, time of use and demand/load profiles on
delivery systems for the determination of cost on an alternative rate billing
scale.
In general, previous resource meters directly measured the amount of
a resource used and maintained a real time clock. The clock in such devices
was used to schedule demand and time of use calculations, as well as,
interval recording of load profile tasks. Demand, time of use and
demand/load profiles must be synchronous in time. Processing all of this
information at the end of a set time period required fast and costly
processors
to avoid the loss of data which would occur at the next scheduled
measurement of data, for example, the rollover to the next minute. Each of
these calculations was a serial process; therefore it was impossible to
absolutely synchronize the resource measurements.
Synchronizing was possible by making periodic measurements that
were valid for a period of time. In order to provide real time measurements,
such intervals had to be kept as short as possible. As a result, costly
processing power was still required to complete all the calculations before
even such short time intervals expired. The busiest processing times
occurred at the end of some predetermined time period, such as at the end of
an hour, the end of a day, at the change of a time of use schedule or at a
scheduled self reading. When some or all of such tasks occurred
simultaneously, a very high demand was placed on the processor to complete
its calculations before the rollover of the next time period. If the processor
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
2
failed to complete its calculations in time, the synchronization of the data
was lost.
Prior methods and devices have been practiced for collecting data on
various states of a resource meter's condition, performance characteristics,
or measurements. One example of a prior art device capable of retrieving
data from a resource meter is shown in commonly owned U.S. Patent No.
5,473,322, entitled "Method and Apparatus for Indicating Meter
Tampering." The exemplary method of the referenced '322 Patent utilizes a
non-volatile memory to store an indicator of a detected "tampering event."
While effective for its purpose, such approach does not detect the actual
demand for a resource or the amount used.
The complete disclosure of such U.S. Patent No. 5,473,322
(including all figures and discussion thereof) is fully incorporated herein by
reference.
SUMMARY OF THE INVENTION
The present invention recognizes and addresses various of the
foregoing limitations and drawbacks, and others, concerning time-
synchronous data collection. Thus broadly speaking, a principal object of
the subject invention is improved methodologies for measuring resource
usage. More particularly, an object is improved methodologies for making
time-synchronous measurements of the resource used or metered.
Another more particular object of the subject invention is to maintain
the measurements for a set period of time in a non-volatile memory.
Another general object of the subject invention is to allow for access
to the stored data for use in computations of resource demand, time of use,
and demand/load profiles on the resource delivery system.
Still another present object of the present invention is to provide an
improved methodology wherein the calculations of resource demand, time of
use, and demand/load profiling can be performed using less powerful, lower
cost microprocessors.
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
3
Yet another present object of the present invention is to perform the
above referenced calculations between measurement intervals so as to avoid
losing the data's time-synchronization.
Additional objects and advantages of the invention are set forth in, or
will be apparent to those of ordinary skill in the art from, the detailed
description herein. Also, it should be further appreciated that modifications
and variations to the specifically illustrated, referenced, and discussed
steps,
features, materials, or devices hereof may be practiced in various uses and
embodiments of this invention without departing from the spirit and scope
thereof, by virtue of present reference thereto. Such variations may include,
but are not limited to, substitution of equivalent steps, materials, means, or
features of those shown, referenced, or discussed, and the functional,
operational, or positional reversal of various features, steps, parts, or the
like.
Still further, it is to be understood that different embodiments, as well
as different presently preferred embodiments, of this invention may include
various combinations or configurations of presently disclosed steps, features,
or elements, or their equivalents (including combinations of steps or features
or configurations thereof not expressly shown in the figures or stated in the
detailed description).
The present invention is directed to a method for providing time-
synchronous measurements of resource usage and to maintain that data for
an established period of time to allow for the use of cheaper, lower power
processors to calculate time-critical values such as demand, time of use, and
demand/load profiles across the resource delivery system. A series of
resource usage snapshots, synchronized with time, are stored in memory.
Each stored value is time stamped to correspond to the moment in time
during which it was measured. As only the real time and resource usage
measurements are required to be time synchronized, the demand on the
processor for performing all the resource use, time of use, demand/load
profiles, self readings, and other tasks can be left to occur when the
processor is not involved in taking the measurements (i.e., the processor
"down time").
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
4
The time between snapshots and thus the "down time" time available
for calculations of time-critical information is determined by the smallest
interval of time used in the measurement of the amount of resource used or
metered. In the instant case, that time is one minute. A history of sixty
snapshots, taken one minute apart, is stored in a ring buffer. This would
provide at least one minute during which an entire hour of time-synchronized
resource usage data was available for performing all the necessary
calculations to determine total resource use, peak time of use, and the
demand/load profiles on the resource delivery system during that hour. The
above calculations could even be run for periods as small as five, ten, or
fifteen minutes. One of ordinary skill in the art would recognize that
smaller demand intervals, for example fifteen minutes, will allow a greater
amount of time to perform calculations on the collected data prior to its
being written over by new data. In the case of a fifteen minute demand
interval, the data would be available for a period of forty-six minutes before
being written over. This data could then be used to more accurately
establish time variable billing rates for the resource.
The invention includes a single, centralized method for calculating
resource usage that utilizes the historical measurements taken by the
measurement systems processor. In order to calculate the total resource
usage, time of resource use, and the demand/load profiles, the processor only
needs a start and stop time interval. The use of the history insures complete
time-synchronization of the data in all the calculations performed and
eliminates the duplication of some calculations in different tasks. As a
result, the calculations are performed in a shorter time with a cheaper, lower
power processor and yet provide more reliable results.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a block diagram showing the method of collecting a
measurement of resource use as the time period has just completed.
Figure 2 is a block diagram showing the method after a measurement
has been taken and the ring buffer, temporary memory, and the accumulator
have been updated.
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
Figure 3 is a flow chart showing the method awaiting a new resource
use indication and when such use is detected the updating of the value stored
in the accumulator.
Figure 4 is a flow chart showing the method determining if a new
5 measurement should be taken due to the beginning of a new time period and
when a new period is detected updating the ring buffer and temporary
memory values.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Accuracy is of great importance in resource metering.
Synchronization of that measured data to time is equally important. Because
consumption of a resource is continuous little time is available during the
measurement of the resource usage to calculate further information which
will allow resource providers to fairly determine time-dependent billing rates
for the resources they provide. To properly obtain that information, high
powered, expensive computer processors have been required that were
capable of performing the calculations necessary during the very limited
time available between data collection. The present invention provides a
method of time-synchronous data collection on the use of a resource. It is,
therefore, capable of providing ample time to perform the calculations
necessary to accurately assess the amount of resource used, the time of use,
and the demand/load profiles generated by such use across the resource
delivery system. This allows the use of lower cost, less powerful processors.
The information required includes requests for the resource, the time
of use of the resource, and demand/load profiles across the delivery system
of the resource. The demand is the amount of a resource consumed during a
programmed interval of time and scaled to one hour. For example, if the
resource were energy, the time interval were 15 minutes and the energy
consumed during that interval were 400 watt-hours, the demand would be
multiplied by 4 (60 minutes divided by 15 minutes) to scale it to one hour.
The total demand for the hour would be 1600 watts.
Time of use divides the day into different periods. Each period of
time will have its own demand and energy consumed. Based on the above
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
6
factors, different rates for the resource axe charged for the different
periods.
Weekdays, Saturdays, Sundays and holidays can all have different time
periods and thus billing rates scheduled. It is therefore very important to
keep track of resource usage over these periods to properly bill the resource
user and to more accurately determine fair billing rates.
The present invention assures the required accuracy by maintaining a
time-synchronous collection of data measured at set intervals over a
predefined period of time. In the instant case, the set interval of
measurement is every minute at the rollover of the minute and the predefined
period is sixty minutes. The method involves using three different memory
locations for storing the measured data to keep track of the total resource
consumed (or metered), the resource consumed during the immediately
proceeding interval and the proceeding sixty minutes worth of resource
usage measurements.
Figures l and 2 are representative illustrations of the method, at the
initiation of and after the completion of taking a measurement, respectively,
showing the three memory locations and the change in values as the method
cycles through from detecting a new resource request (step 1) to updating all
the memory values (steps 3a-6) and finally updating the accumulator value
(step 7). More particularly, Figure 2, represents the method awaiting the end
of "History Minute No. 8." As always, the accumulator 10 represents the
total resource energy (i.e., 1268) since the initiation of the metering
device.
The temporary memory 12 value (i.e., 1267) represents the accumulator
value as measured at the end of History Minute No. 7. And finally, the value
(i.e., 952) that is currently shown in the array 14, and more precisely in
"History Minute No. 8," represents the measurement taken 61 intervals ago.
One of ordinary skill in the art will recognize that while the time intervals
in
this example are referred to as "History Minutes," any interval between
measurements can be established as required by the resource provider.
With more specific reference to the subject features, Figures 3 and 4
represent logical flow charts by which one of ordinary skill in the art may
understand the steps, which may be implemented in either dedicated
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
7
hardware or programmable haxdwaxe with computer software
implementation (or a combination thereof), for practice of various
embodiments of the subject invention.
It should be further understood by those of ordinary skill in the art
that the subject methodology may involve processes or functions that are
operating simultaneously in some instances, consecutively in some instances,
and repetitively in some instances. In other words, various aspects of the
subject invention may operate independently from one another, as well as in
reaction to changing characteristics associated with the meter (or device)
with which the method is practiced.
Those of ordinary skill in the art will appreciate that the "steps"
recited for the present methodology do not necessarily mean or intend a
specific and singular chronological order thereof, as will be otherwise
completely understood from the full disclosure of the present application.
As best seen in exemplary Figs. 3 and 4, the method begins with the
alternate process block of step 1, which is looking for any new resource
request. When such a resource request is detected, in accord with steps 2
and 3, the method determines if an interval of time has just ended, indicating
a need to take a measurement of current total resource usage. If the current
interval has not rolled-over, as determined in the decisional block of step 3,
the method adds the amount of resource used to the amount already stored in
the accumulator as indicated in step 7. The method then returns to step 1 to
determine if any other requests for the resource have occurred.
When first initiated or when reinitialized all the values may be set as
zero. The accumulator therefore maintains a running total of the resource
used from either the initial start of the system or the point in time where it
was reinitialized.
Assuming the meter to have been reinitialized (i.e., all values axe
zero), if the method determines that an interval has just ended and with a
request for the resource having been detected, according to step 1, the
current accumulator value will be placed in a temporary memory as dictated
in step 5. This temporary memory maintains what is the most recent
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
8
measurement, the accumulator value at the rollover of the interval. With this
information alone, the processor is capable of determining the total resource
usage, the usage over the proceeding interval, and the time of use of the
resource.
According to step 4, the value stored in the temporary memory (i.e.,
zero) at that time is moved into the first location in the'storage memory
array
and will be time stamped as minute zero or the value in the accumulator at
the initiation of the method. The value in that location is written over
(i.e.,
discarded) as shown in step 3a. If utilized properly, the storage memory
array locations can correspond to the time interval during which they were
measured. One of ordinary skill in the art, however, will recognize that any
system of identification of the data in relation to when it was measured for
the purpose of retrieving the stored measurements is within the spirit and
scope of the present invention.
When the processor detects the end of the second interval (see step
3), the value located in the temporary memory is moved into a storage
memory as described in step 4 and is associated with a time stamp to indicate
that it was measured at the end of the first interval of the method. In this
way, the storage memory can best be thought of as a historical array of
measured values. The method, according to step 5, then replaces the value
that was in the temporary memory with the immediately proceeding value of
the accumulator and finally updates the accumulator, as shown in step 7, in
order to maintain its running total of the amount of resource used.
For example, assume three measurements have been taken over four
intervals - I-1, I-2, I-3, and I-4, the method can be followed numerically as
shown in Table 1.
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
9
___ TABLE 1
Interval Accumulator Temp. Memory Storage Memory
Value Value Arra Value s
Initiation - Beginning0 0 0
of I-1
Rollover to I-2 20 20 0
During I-2 27 20 0 - measured
at the
reset of method
Rollover to I-3 33 33 20 - measured
at
end of I-l;
0 - measured
at
reset of method
Rollover to I-4 44 44 33 - measured
at
end of I-2;
20 - measured
at
end of I-l;
0 - measured
at
reset of method
At the initiation of the method all the readings will be zero (note however
that the readings can be set at any numerical value). With the fixst request
for the resource, as detected in step 1 of Fig. 3, the value in the
accumulator
will rise accordingly via steps 2, 3, 6, and 7. Assuming the request is for
twenty units of the resource, the value in the accumulator will be twenty.
Provided there is no further resource usage during I-1 and there is a rollover
from I-1 to I-2, as detected in step 3, the value in the temporary memory will
be adjusted to read twenty in accord with step 5. The storage memory values
will still be zero as dictated by step 4.
If during I-2, there is a request for seven units of the resource, the
value in the accumulator will rise to twenty-seven per steps 1-3, 6 and 7.
Absent the rollover of an interval, no other values will change. If just prior
to the end of I-2, there is a further demand for six units of the resource,
the
accumulator value will rise again to read thirty-three and no other values
will
change.
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
When I-2 rolls-over into I-3, the processor will move the value in the
temporary memory into the storage memory (as shown in step 4) and time
stamp it to indicated that it was actually measured (i.e., transferred from
the
accumulator) at the end of I-1. The value in the accumulator will then be
5 placed in the temporary memory as dictated in step 5. At the rollover from I-
3 to I-4, steps 4-7 will be followed as above. Instead of replacing the value
in the storage memory, however, the storage memory contains an array to
maintain all of the measurements taken during a predefined time period
along with their associated time stamps. In the instant case, the array will
10 hold sixty measurements with the sixty-first measurement being located in
the temporary memory.
When the rollover to minute sixty-three occurs, the method will need
to place the value in temporary memory (the measurement taken at the end
of minute sixty-two) into the storage memory array. The storage memory
aiTay having run out of locations to store data, will overwrite the value
stored
in the first space (the measurement taken at the end of minute one) with the
value measured at the end of minute sixty-one just as the zero value was
written over in the above example. In this way, should values for resource
usage, time of use, and demand/load profiles across the resource delivery
system be desired for periods of five, ten, or fifteen minutes, the
measurement from any particular minute is easily found by the processor and
no laxge memory storage capacity is required.
This method therefore provides for the storage of the proceeding
sixty-one minutes worth of measurements to be maintained in memory. By
doing so, during the one-minute interval between measurements when the
processor is seeking only a new request for the resource (i.e., the
processor's
"down time"), the processor is free to run calculations on usage, time of use,
and demand/load profiles utilizing identical time-synchronous data. This
provides two significant advantages over previous measurement and
calculation methods. First, all the calculations can be made during the
"down time" of the processor allowing the use of lower power, cheaper
processors. Second, the data used throughout all the calculations performed
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
11
during the "down time" of any interval is identical. Despite using slower
processors, all the calculations can easily be completed during the
processor's "down time."
There are times when the values in the storage memory array,
temporary memory, and accumulator cannot be updated. This would occur
when testing or maintenance is being performed on the resource meter. In
such instances, the method is still valid. Should the interruption in the
supply of the resource last less than one minute, the method would retain all
of the previous measurements in memory and treat the interruption as if no
new energy for the resource existed during that time interval (i.e., method
step 1 would get only a "NO" response). At the rollover of the next minute a
measurement would be taken and the method would be followed as
described above. As no resource was delivered, no improper addition to the
user's bill for the resource would appear.
If the interruption in the supply of the resource lasts longer than one
minute the temporary memory value still gets moved into its appropriately
time stamped location in the storage memory array per step 4 and the
accumulator value gets moved into the temporary memory in accord with
step 5. Thereafter, however, the accumulator value will not change. As a
result, all of the following measurements (i.e., storage memory array values)
will be identical to that shown in the accumulator at the rollover of the
minute immediately following the interruption in the supply of the resource.
Thus at the rollover of the second interval after a longer than one minute
interruption, all the steps will be followed as described above but all the
newly entered values will be the accumulator value at the interruption of
service. For purposes of the calculations to determine resource usage, time
of use, and demand/load profiles, this will result in the acknowledgment that
no resource was supplied during the period of the interruption and will not
result in improper charges to the user.
Although a preferred embodiment of the invention has been
described using specific terms and devices, such description is for
illustrative
purposes only. The words used are words of description rather than of
CA 02415233 2002-12-19
WO 02/01605 PCT/USO1/11496
12
limitation. It is to be understood that changes and variations may be made
by those of ordinary skill in the art without departing from the spirit or the
scope of the present invention, which is set forth in the following claims. In
addition, it should be understood that aspects of various other embodiments
may be interchanged both in whole or in part. Therefore, the spirit and scope
of the appended claims should not be limited to the description of the
preferred version contained herein.
