JPS5944858B2 - Demand monitoring control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a demand monitoring and control device that monitors current power so that the power demand does not exceed the contract power demand during a demand period, and performs load control when the power demand is about to exceed the contract power demand.

When performing automatic load shedding in this type of equipment,
As shown in Figure 1, the current power value is set to 0 at the start of the demand time period, and at the end of the demand period, it exceeds the ideal load curve set to the contract power demand value Q, and the predicted power demand value R is set to the target power demand value, for example, the contract Power level at which demand power Q is cut off (
There is a method that performs load shedding when the power exceeds (the power value that should be adjusted at that time) or more.

There is a control method for load shedding that does not restore the load within the specified time limit once it has been shut off, but for power consumers who want to use electricity efficiently, it is preferable to restore the load as soon as there is surplus power. . Therefore, regarding load restoration (9) When the current power falls below the ideal load curve and the predicted power demand value falls below the target power demand value by more than the restoration level (the power value to be adjusted at that point), the load is restored. Generally, the cut-off power level and the recovery level are equal.

This is because the electric power U to be adjusted at that time is expressed by the following equation. U■(R-Q)·Th Note that R is predicted power demand, Q is target power demand, T is demand time period, and is demand elapsed time.

When the power U to be adjusted is..., it is in excess, and when it is ←), it is in a surplus state. In case of excess, when the load power that can be cut off for one circuit becomes equal to this adjusted power U, a load cutoff signal is issued and the load is cut off, and conversely, if there is a margin, the power U that should be input can be turned on. If the load application signal is issued and the load is applied when the power becomes equal to the load power, the predicted power will match the target power demand. Here, when there are multiple loads to be controlled, it is desirable to set a load power value for each load and control the load that matches the adjusted power value.

However, in order to make this setting, for example, a digital switch or the like must be installed in each of the devices, which is very complicated, reduces reliability, and increases cost. Therefore, the average power value of a plurality of loads to be controlled is used as the signal of each load power, that is, the control level. Adjusted power U
= {(R-Q)T half〒} is at the start of demand (t=O)
In this case, U=R−Q.

If the demand time limit T is 30 minutes, after 29 minutes U
= 30(R-Q), which is 30 times larger than at the start. This means that even if the difference between the expected power R and the target power demand Q is the same at the start of the demand time period and after 29 minutes have elapsed, the adjusted power value U will be as much as 30 times different, and the load will not be controlled in the second half of the time period. This indicates that in order to match the predicted power R with the target power demand, it is necessary to cut off a load with a considerably large load capacity. In order to avoid cutting off a large load, it is necessary to position the current power value approximately on the ideal load curve as shown in FIG.

In Figure 2, when the elapsed time is 27 minutes, the current power B
is above the ideal load curve A, and when the predicted power R27 at this time exceeds the target power Q and the adjusted power exceeds the control level, load shedding is performed. Also, the elapsed time is 2
At 8 minutes, the current power is below the ideal load curve A,
When the predicted power R28 at this time is smaller than the target power Q and the adjusted power exceeds the control level, the load is turned on.

If the control level when turning off the load is equal to the control level when turning on the load, the current power is on the ideal load curve, so a slight change in the current power will cause it to go above or below the ideal load curve. As a result, the predicted power will also change accordingly. Because of this change, even if the average value of the load to be cut off is set as the control level, the load capacity that is actually turned on and cut off is not necessarily equal to the control level.
If there is a difference between these, there is a possibility that the load cut-off signal and the load-on signal will be output alternately in each calculation cycle (this is called hunting), resulting in unstable control as a demand monitoring control device. This was extremely inconvenient. An object of the present invention is to provide a demand monitoring and control device that eliminates the above-mentioned drawbacks.

Therefore, hunting of the control signal output is prevented by providing a difference between the cutoff level and the cutoff level. An embodiment according to the present invention will be described below with reference to FIG.

7 The demand monitoring and control device 1 receives pulses from the watt-hour meter 2 with a transmitter device that measures the amount of power used and transmits pulses proportional to the measured value.

In the control device 1 that receives this pulse, the pulse is supplied to the current value counter 3 and the sampling counter 4. The counter 3 counts the pulses, calculates the current demand power P, and displays the value on the current value display 5. On the other hand, the sampling counter 4 counts the pulses supplied from the electricity meter 2 during the sampling time Δt (for example, 1 minute), and calculates this counted value as the amount of electricity used per unit time (1 minute) at the sampling time Δt. It can be calculated as the sampling value Δp/Δt. 6 is a remaining time clock circuit that calculates the remaining time (T-t) of the demand time limit T (t is the current time) and displays the value on the remaining time display 8.

9 is a multiplier that calculates the product of the output △p/△t of the sampling counter 4 and the remaining time clock circuit 6 and (T-t).
T-t) is calculated.

The predicted power generator 10Δt is the output P of the current value counter 3.
and the output failure of the multiplier circuit 9 (T-1) are supplied, and the predicted power consumption R{R=
P+peak X·(Tt)}, and its predicted power value R is displayed on the predicted value display 11.

Reference numeral 12 denotes a target power demand setting device, in which a target power demand Q, which is the amount of power to be used at the end of the demand time period T, for example, the contract power demand, is set.

13 is a difference/comparison circuit, which calculates the difference (R-Q) between the output R of the predicted power generator 10 and the target power demand Q set in the target power demand setting device 12, and its magnitude R>Q, R ≦Q
and generates a signal to that effect.

14 is a regulated power generator, which outputs the difference comparator 13 (R
-QX is supplied with the output (T-t) of the remaining time clock circuit 6, and the power to be adjusted U{U=T (R-Q)T-,} is calculated.The value is displayed on the adjusted power display 15. Is displayed.

Reference numeral 16 denotes an ideal load curve generator, which generates an ideal load curve A that is O at the start of the demand time period T and becomes the target power demand Q at the end of the demand time period as the demand time period passes.

Reference numeral 17 denotes a first comparison circuit, which is supplied with the output P of the current value counter 3 and the output A of the ideal load curve generator 16, and 6 calculates the difference between P and A (P-A), the magnitude ratio of P and A, P≧A, If P<A is calculated, a signal to that effect is generated.

Reference numeral 18 denotes a control level setter, in which the average load power K per sampling time Δt is set for one group of loads to be controlled, for example, n groups.

Reference numeral 19 denotes a retrospective level generation circuit, which is supplied with the output (T-t) of the remaining time clock circuit 6 and the output K of the control level setter 18, and calculates the cutoff level X {X=K・1-1}T. .

20 is a second comparison circuit which is supplied with the difference output (R-Q) of the first difference comparison circuit 13 and the output X of the cutoff level generation circuit 19, and there is no comparison between (R-Q) and X. (R-Q)
When ≧X, a signal to that effect is generated.

Reference numeral 21 denotes a closing level generation circuit, which is supplied with the output (Tt) from the remaining time clock circuit 6 and the output K of the control level setter 18 to generate the closing level T-(t-m·△t) Y{Y= K.? } is calculated.

(However, m=1, 2, 3,...) That is,
The input level Y at the time point t is earlier than the cutoff level X by the sampling time Δt(7)m times. That is, the width of Y is larger than the width of X. 2
2 is a third comparison circuit, which outputs the difference/comparison circuit 13 (R
-Q) and the output Y of the input level generation circuit 21 are supplied,
There is no comparison between Y and (R-Q). When Y≧(R-Q), a signal to that effect is generated.

Reference numeral 23 designates a cutoff command circuit to which the output terminals of the difference/comparison circuit 13, the first comparator 17, and the second comparison circuit 20 are connected.

The cutoff command circuit 23 has three inputs of R>Q and P>A, respectively.
, X≦(R-Q) are simultaneously supplied, a cutoff command signal is supplied to the load control circuit 24. When the load control circuit 24 receives the cutoff command signal, it generates a signal to cut off one group of loads among the n groups of loads to be controlled. 25 is an input command circuit, which includes a difference and comparison circuit 13;
The respective output sides of the first comparison circuit 17 and the third comparison circuit 22 are connected.

The input command circuit 25 has three inputs of R≦Q, P≦A, respectively.
, Y≧(R-Q) are simultaneously supplied, a closing command signal is supplied to the load control circuit 24. When the load control circuit 24 receives the turn-on command signal, it generates a signal to turn on one group of loads among the n groups of controlled loads that have been cut off. Now, the operation of one embodiment configured as described above will be explained.

Pulses proportional to the amount of power used from the power meter 2 with transmitter device are counted by the current value counter 3 and displayed as the current demand power P on the current value display 5.

The current demand power P, which is the output from this counter 3, is supplied to the predicted power generator 10.

In this predicted power generator 10, demand △
Predicted power usage at the end of time period T △PR{
R=P+1・(Tt)} is calculated.

This Δt predicted power R is displayed on the predicted value display 11 and is also supplied to the difference/comparison circuit 13.

In this difference/comparison circuit 13, a comparison is made with the daily target power demand Q from the target power demand setting device 12 (R-Q), R
>Q, R≦Q is calculated and output.

This difference signal (R-Q) is supplied to the regulated power generator 14 where the remaining time from the remaining time clock circuit 6 (T-t
) and the adjusted power U{U=(R-TQ)? } is calculated.

This adjusted power U is displayed on the T-T° adjusted power display 15.

Further, this difference signal (R-Q) is supplied to the second and third comparison circuits 20 and 22 and is compared with the cutoff level X from the cutoff level generation circuit 19 and the closing level Y from the closing level generator 21. be done.

If the difference signal (R-Q) is equal to or larger than the cutoff level X, the second comparison circuit 20 supplies a signal to that effect to the cutoff command circuit 23. On the other hand, the difference signal (
If R-Q) is close to or smaller than the input level Y,
A signal to that effect is supplied from the third comparison circuit 22 to the input command circuit 25. At this time, since the width of the thrower level Y is larger than the width of the retrospective analysis level It will be output.

In addition, a comparison signal (R>Q) and (R≦Q) from the difference/comparison circuit 13 are supplied to a cutoff command circuit 23 and a closing command circuit 25 to which the second and third comparison circuits 20 and 22 are supplied.
) and the comparison signal from the first comparison circuit 17 (P>A)
and (P≦A) are provided. When the signal (R-Q)≧X, R>Q, P>A is supplied to this cutoff command circuit 23, a load cutoff command is sent from this circuit 23 to the load control circuit 2.
4.

On the other hand, the input command circuit 25 receives a signal (R-Q)≦Y,R
When ≦Q and P≦A are supplied, a load application command is supplied from this circuit 25 to the load control circuit 24. Load switching is performed in the manner described above.

Now, assuming that the cutoff level Load control is performed. Due to the effect of this load control, when R<Q, (R - Q) < Shutdown and shutoff are repeated and hunting occurs.However, as explained above, the tζ control level K is set, and the shutoff level X is set according to this K and the remaining time.
1 pitcher level Y is generated, and the width of this level Y is greater than the width of level X, and by changing the value of m that generates level Y, the width of This eliminates the possibility that the load cutoff signal and the load on signal are generated alternately within a short period of time in each calculation cycle. Therefore, stable demand monitoring control becomes possible.

[Brief explanation of the drawing]

1 and 2 are characteristic curve diagrams for explaining conventional operation, and FIG. 3 is a block diagram of an embodiment according to the present invention. 1... Demand monitoring control device, 3...
Current value counter, 4... Sampling counter, 6... Remaining time clock circuit, 9... Multiplier, 10... Predicted power generator, 12...・・・・・・
・Target power demand setting device, 13...Difference/comparison circuit, 16...Ideal load curve generator, 17...
...First comparison circuit, 18... Control level setter, 19... Cutoff level generation circuit, 20...
... Second comparison circuit, 21 ... Closing level generation circuit, 22 ... Third comparison circuit, 23 ...
... Cutoff command circuit, 24 ... Load control circuit,
25... Closing command circuit.

Claims (1)

[Claims] 1. In a demand monitoring control device that monitors demand according to target power demand based on the number of pulses from a power meter with a transmitter, if the current power demand exceeds the ideal load curve,
Furthermore, when the predicted power demand exceeds the target power demand value by more than the current cutoff power width, the controlled load is shut off, and when the load is turned on, the current demand power is below the ideal load curve and the predicted power demand is the target. 1. A demand monitoring and control device characterized in that a load is turned on when a demand power value falls below an input power width having a width larger than a cutoff power width at that time.