JPS6016131A - Demand power monitor controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a power demand monitoring and control device that manages maximum power demand so that it is equal to or less than a target power.

[Background of the invention]

Conventional power demand monitoring and control devices, for example, count the transmitted pulses of a power meter with a transmitting device, calculate and display a predicted power demand when the demand time limit has elapsed based on this counted value, and also use this value as a predictive value. An alarm will be generated and the load will be cut off. The operating principle of such a device will be explained using FIG.

In FIG. 1, the horizontal axis represents the elapsed time of the demand time limit, where the demand time limit is T (generally 30 minutes). The vertical axis is the power demand. a
Demand increases over time! In the curve showing the increase in power, let P be the current power demand at elapsed time t, and let Δp be the increase in power demand in the short (2) pulse integration time interval Δt (fixed time) a little before this point, The predicted power demand R at the time of completion of the demand time limit is calculated by the following equation.

Δt is 1 to 5 depending on the load situation of the electricity consumer.
The value of the minute is taken.

In addition, Δp is expressed as Δp=Δnxw...Old...(2), where the number of pulses input within Δn1 is the weight (kWH) of one pulse and W (constant). .

As can be seen from equation (1) in FIG. 1, the accuracy of the predicted power demand H is greatly influenced by the value of Δp, or in other words, the value of Δn. For example, considering a general case where the number of pulses input per hour is 2000 pulses at full load power, if the target power is 70% of the full load power, about 20 pulses are counted per minute. A power meter with a transmitter is an integral type and outputs one pulse when measuring the amount of power equivalent to the pulse weight, so in the worst case two pulses may be input in this one minute due to the difference in time. In some cases, these two pulses may occur in the previous minute and the next minute. When averaged over a long period of time, this difference is not a problem, but when pulse counting is performed over a short period of time, this error becomes large and becomes an error in the predicted power demand. In order to reduce this error, lengthening the pulse counting time, that is, a certain period of time, may not be consistent depending on the load situation of the power consumer, and generally when the demand time period T approaches completion, If you notice a sudden rise in vehicle power, you will miss the whole thing.

Also, the number of input pulses within a certain time Δ is set to n, and the time interval of input pulses is Δ1F11sΔty4ss...
・.

There is already an idea that when ΔlPm-1-m...(3). This method uses Δ1 within a certain period of time when load fluctuations are large. The large dispersion in the values causes errors, and since the counting within a certain period of time is repeated within the demand time period, there is a possibility that errors may accumulate.

[Purpose of the invention]

The present invention was made in order to eliminate the disadvantages of the queen, and makes it possible to accurately calculate the predicted power demand by accurately counting the number of input pulses within a certain period of time. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In Figure 2, 1 represents the amount of power in the circuit PT.

This is a power meter with a transmitter that measures power via CT and transmits pulses proportional to the amount of power used. 2 is a pulse number counter that counts these pulses.

3 is an increment counter that counts the number of pulses within a certain period of time, and the start and end of 3 are instructed by a certain period of time elapsed signal from the clock 4. 5 is the time interval Δ1.5 of pulses inputted one after another. This is a counter that counts the pulse reception time tpm and the pulse interval register 6, and the latest values thereof are always stored in the pulse interval register 6. In response to the predetermined time elapsed signal from the clock 4, the fractional pulse counter 7 calculates the fractional pulse Δn based on the fixed time end time tm according to the following formula.

When ≦Δt, Δn remains as it is. t
When m-tp>Δt, the power usage has suddenly decreased, indicating that the next pulse will arrive later than the single pulse.

In this case, Δn is the average, Δn=Δn/(generally Δ
n'=0.5). There are few cases in which this happens, and the prediction error can be kept to a minimum. Accordingly, the sum of the obtained Δn and the increment counter 3 is calculated by the adder 8. The contents of the adder 8 are input to the arithmetic circuit 9, and Δ
After calculating p=Δn (number of pulses) x pulse weight (kW H/pulse), calculate the predicted power demand R using equation (1). The output of the arithmetic circuit 9 is compared with the target power set from the target power setting device 10, and depending on the comparison result, the alarm/load cutoff circuit 11 and the like are operated. After counting Δn, the fractional pulse counter 7 adds the calculation result of 1-Δn to the increment counter 3 so that it can correctly count the number of pulses for a certain period of time next time. Incidentally, after the increment counter 3 sends the data to the adder 8, it immediately starts counting pulses for a certain period of time. At this time, the first pulse is not counted, but the above-mentioned value (1-Δn) is counted instead.

As an embodiment of the present invention, alkali,
The pulse interval register 6 is not limited to one circuit,
It memorizes the past several pulse intervals in multiple registers, predicts the time when the next pulse will arrive based on trends such as gradual increase/decrease in this data, and counts within a certain period of time based on the predicted time. There is also a method of calculating a power fraction pulse.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to accurately count the increment of input pulses, and the power demand can be accurately predicted, so that warnings and load shedding can be appropriately performed. When the load temporarily decreases, the number of input pulses within a certain period of time decreases, so the results of pulse counting using this method are particularly large.

Note that although this method has been described as an operation of a hardware circuit, it can also be implemented using software.

[Brief explanation of drawings]

FIG. 1 shows the operating principle of an embodiment of a conventional device, and FIG. 2 shows a block diagram of an example according to the present invention. In Fig. 2, 1... watt-hour meter with transmitter, 2...
Pulse counter, 3... Incremental counter, 4... Clock,
5... Pulse interval counter, 6... Pulse interval register, 7... Fractional pulse calculator, 8... Adder, 9...
...Predicted power demand calculator, 10...Target setting device, 11
. . . Comparator, 12 . . . Alarm/load controller. Agent Patent Attorney Akio Takahashi

Claims (1)

[Claims] 1. Receive and count the transmitted pulses of the watt-hour meter with a transmitting device, and determine the demand based on the increment of the counted value in a certain period of time, the remaining time of the demand time limit, and the electric power at the end of this certain period of time. Calculate the predicted power at the time of completion of the time limit, calculate the adjusted power from this predicted power and the target power to be managed, and issue a warning when the predicted power exceeds the target power. Adjusted power and cutoff load capacity In a power demand monitoring and control device that compares the values of By calculating the time between the completion of a certain period of time and the time of pulse input just before that, and calculating the ratio between this time and the latest value, the fractional number of pulses based on this ratio value can be calculated as follows: The number of input pulses within a certain period of time is counted and the increment is calculated by assuming that the input pulses are input between the time when the pulse is completed and the time when the immediately preceding pulse is input.(1)
-- A power demand monitoring and control device characterized in that the increment is calculated on the assumption that a fractional pulse obtained by subtracting this fraction from 1 is entered for the next fixed period of time.