JPS5836198Y2 - Demand power monitoring device - Google Patents

Description

[Detailed explanation of the invention] This invention prevents the possibility of the demand power exceeding the contract power, since if the demand power exceeds the contract power, a relatively high penalty fee must be paid for the excess amount. The present invention relates to a power demand monitoring device that prevents excess power.

Conventionally, this type of device has been a mechanical two-stage alarm demand wattmeter or an electronic continuous comparison demand wattmeter.

The mechanical type uses a combination of gears and cams to reduce the demand power by 60% (or 70%, or 8%) of the time limit T as shown in Figure 1.
0%...), 60% of contract power Q
The target value is 0.6 Q (or 0.7 Q,
0.8Q...) is set.

If the time required for the circuit's power demand to reach 0.6Q is earlier than 0.6Q, which is 60% of the power demand time limit T, an alarm is generated as there is a risk of exceeding the contract power. If it is slower than 6T, no alarm will be issued as there is no risk of exceeding the contracted power.

Furthermore, alarm points are set at five points slightly smaller than Q, and when h reaches these points and point C, an alarm is generated regardless of time.

In this way, the power demand is monitored in two steps to ensure that it does not exceed the contract power, but in the case where the load is light in the first half and the power demand m increases rapidly in the second half, the D point that reaches 0°6Q is 0. Since it is slower than 6t, at point E, which reaches the 5th point at which an alarm is issued, there is no longer enough time to reduce the power demand of the circuit even if the alarm is issued.

Such a mechanical device has the disadvantage that it is difficult to accurately manage power demand because there are few checkpoints to check.

On the other hand, in the electronic method, as shown in Figure 2, the straight line q obtained by generating pulses at a constant pace that reaches the contracted power Q within the power demand time period T is constantly compared with the power demand of the circuit, and it is determined that h exceeds q. At point A, a warning is issued as there is a risk of exceeding the contracted power.

Although this type of device can perform more detailed management than the mechanical method described above, in cases where the load is light in the first half and the power demand m rapidly increases in the second half, the alarm generation point G is delayed and control may become too late. There are drawbacks that arise.

The present invention has been developed in view of these points, and aims to more reliably manage power demand by discovering as early as possible whether there is a risk of exceeding the contracted power.

Hereinafter, this invention will be explained in detail with reference to an embodiment shown in the drawings.

In FIG. 3, the amount of power in the load circuit 1 is measured by a power meter 4 with a transmitting device connected to the secondary terminal of PT2°CT3, and a pulse proportional to the amount of power is transmitted.

These pulses are counted by counters 5 and 6. The counter 5 returns to zero every demand power time period T by the zero return signal 7, and the counter 6 returns to zero every demand power time period T by the zero return signal 7.
It returns to zero at every shorter time interval jt.

The remaining time 8 is calculated by subtracting the elapsed time t from the power demand time limit T (Tt).

Then, the multiplication circuit 9 calculates the product of the remaining time (Tt) and the count value of the counter 6.

Furthermore, the addition circuit 10 adds the sum with the count value of the counter 5 obtained in step 9.
When calculated as , the value becomes the predicted value 11 of the power demand at the end of the power demand time period T assuming that the power at that point is constant thereafter.

This predicted value and a preset contract power 12 are compared in magnitude by a comparison circuit 13, and if the predicted value 11 exceeds the contract power 12, an alarm signal 14 is generated.

That is, in FIG. 4, the count value of counter 5 at time t corresponds to Pt, the count value of counter 6 corresponds to AP, and the remaining time 8 corresponds to Tt.

Therefore, the predicted value 11 is JP P t + -X (T - t ), idt, so here, (if 1 is a unit time, Pt-
1-(PX(T-t)=P The power demand P at the end of the power demand time period T when the power at the next point continues to be constant is predicted.

Then, this P is compared with the contract power Q, and if P>Q, an alarm is issued, so the alarm is issued at a point earlier than point A, which is the alarm occurrence point according to the conventional electronic method.

Also, in the case of canceling the alarm, in this method it is done at one point, but in the conventional electronic method it is done at point H, which is much delayed.

In this way, according to this method, the amount of power up to and at that point is measured and the final power demand at the end of the time period is predicted from that value, so the results can be obtained as soon as possible in response to the movement of power demand. Since it is possible to know the power demand, it is possible to perform highly accurate and detailed management that incorporates future changes, which was extremely difficult with conventional methods.

Nowadays, power management is becoming increasingly important from the perspective of energy conservation, and the power demand monitoring device of the present invention is highly practical and expected to be effective.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the operation of a conventional mechanical power demand monitoring device, FIG. 2 is an explanatory diagram of the operation of a conventional electronic power demand monitoring device, and FIG. 3 is a block diagram of the device according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of its operation. In the figure, 1 is a load circuit, 2 is a PT, 3 is a CT, 4 is a power meter with transmitter, 5 and 6 are counters, 7 is a zero return signal, and 8
9 is the remaining time, 9 is a multiplication circuit, 10 is an addition circuit, 11 is a predicted value, 12 is contract power, and 13 is a comparison circuit.

Claims (1)

[Scope of utility model registration request] A circuit that counts pulses corresponding to the amount of power used at any point in the power demand time limit for a unit of time going back from the above-mentioned arbitrary time point, and uses the counted value as the power value at that time, and the remaining time from the above-mentioned arbitrary point to the end of the time limit. A multiplier circuit that calculates the product of the value obtained by dividing time by the above unit time and the above power value, and a counter circuit that counts pulses proportional to the amount of power used and returns to zero at each demand time at any point in time. A power demand monitoring device comprising an addition circuit that calculates the sum of the counted value and the multiplication circuit and sets the value as a predicted power demand value at the end of the power demand time period.