JPH0154934B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a method for controlling the load to prevent the power consumption from exceeding the target power without reducing productivity even when the adjusted power exceeds the range of power that can be cut off. The present invention relates to a load control method for a demand control device that can be used.

Large electricity consumers usually enter into an electricity supply contract with an electric power company. After the contract is signed, care must be taken not to exceed the amount of electricity stipulated in the contract. For this reason, a demand control device is used to control the load. As a method of controlling the load,
For example, a method is used in which a priority is set for each load, and when the load is cut off, the load is cut off from the one with the lower priority, and when the load is turned on, the load is turned on from the one with the higher priority. In conventional equipment of this type, loads are turned on or off based on unilateral decisions made by the equipment, so loads that are directly involved in production activities cannot be controlled, and loads that are not directly involved in production, such as air conditioners, cannot be controlled. can only be controlled. If a load related to production activities is forcibly controlled on and off, the power consumption will fall within the target power, but productivity will decline.

The present invention has been made in view of these points, and consists of a first load group that is directly involved in production activities and a second load group that is not directly involved in production activities such as air conditioners.
Normally, the amount of power is adjusted by on/off control of the second load group, and if it becomes clear that the power consumption will exceed the target power by controlling only the second load group. A load control method that controls only the first load group by cutting off loads that are not related to production activities such as idle operation, and keeps the power consumption within the target power and does not reduce productivity. This has been realized. Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an electrical connection diagram showing an embodiment of demand control for explaining the present invention. In the figure, reference numeral 1 denotes a power meter with an oscillator that receives signals from PT and CT connected to power line 1 and outputs pulses corresponding to the power used. 2 is a current power counter that receives output pulses from the power meter. Reference numeral 3 designates an instantaneous power counter which similarly receives the output pulses from the watt-hour meter 1 and the output pulses from the clock generator 4 and calculates the instantaneous power ΔW/Δt from the amount of power used ΔW within a unit time Δt. Reference numeral 5 denotes a remaining time measuring circuit which receives the output of the clock generator 4 and counts the remaining time (Tt) of the demand time limit T at time t. 6
is a multiplier that multiplies the output (Tt) of the timer circuit by the output ΔW/Δt of the instantaneous power counter 3.

7 is the output of the multiplier (ΔW/Δt) (T-t)
and the output _W1 of the current value counter 2, and calculates the predicted power _WS . 8 is
This is a target power setting device that sets target power W _D.
Reference numeral 9 denotes an adjusted power calculator that receives the output W _S of the predicted power calculator 7 and the set value W _D of the target power setter 8 and calculates the adjusted power W _C. 10 is a control circuit that receives the output W _C of the adjusted power calculator 9.
For example, a microcomputer is used as the control circuit. The control circuit 10 also performs various other controls. The control circuit includes loads L _A1 , L _A2 ...
Contacts SW ₁ , SW ₂ , etc. corresponding to are connected.
Here, the loads L _A1 , L _{A2 .} . . are loads for production equipment, and are directly related to production.

Reference numeral 11 denotes a load control signal generation circuit that receives the output of the control circuit 10 and generates an on/off signal for each load. The output of the load control signal generation circuit is
As shown in the figure, it is divided into L _A group and L _B. L _A
group is a signal group for controlling the production equipment loads LA ₁ , LA ₂ . . . described above. L _B is a load group that is not directly involved in production activities such as air conditioners. The present invention will be explained using a circuit configured in this manner.

As described above, in the present invention, loads are divided into a first load group related to production activities and a second load group not directly related to production activities. It is now assumed that power is turned on to all of the first load group, and some of the power is turned on to some of the second load group. In this state, the oscillator-equipped power meter 1 outputs pulses according to the power used. Current power counter 2 is at time 0.
The power consumption W ₁ from to time t ₁ is output. Second
The figure is a diagram showing a demand curve. In the figure, f ₁ is an actual demand curve, and f ₂ is an ideal curve. On the other hand, the instantaneous power counter 3 receives the output of the oscillator-equipped power meter 1 and the output pulse of the clock generator 4, and calculates the instantaneous power at time t from the amount of power increase ΔW within the unit time Δt immediately before time t. Calculate and output ΔW/Δt.

The multiplier 6 outputs the output ΔW/of the instantaneous power counter 3.
It receives Δt and the output (T-t) of the remaining time counting circuit 5, multiplies them, and outputs (ΔW/Δt)(T-t). The predicted power calculator 7 receives the output W ₁ of the current power counter 2 and the output of the multiplier 6 and calculates the predicted power.
Calculate W _S. W _S is expressed by the following formula.

W _S = W ₁ + (ΔW/Δt) (T-t) ...(1) The adjusted power calculator 9 uses the output of the predicted power calculator 7
After receiving W _S and the set value W _D of the target power setter, the adjusted power Q _C expressed by the following equation is calculated.

W _C = (W _D - W _S )/(T-t) ... (2) Adjusted power W _C is the amount of load that needs to be increased or decreased in order to match the demand to the target value W _D. This is the average power when adjusted on average over time (Tt).

Under normal conditions, the adjusted power W _C can be sufficiently covered by the on/off control of the second load group. Therefore, by cutting off the load when W _C is positive and turning on the load when W _C is negative, it is possible to use the full contract power and perform load control so as not to exceed the target power. Amount of electricity that can be cut off Q _C
is set by the customer in advance using a cut-off power setting device (not shown).
It is possible to set the control circuit 10 from the above. Increasing the cut-off power will result in
It is also necessary to increase the number of loads that can be interrupted.

However, as shown in FIG. 2, the predicted power W _S increases and even if all the cut-off power Q _C is cut off, the power used in the final time period T may still exceed the target power W _D. In such a case, in order to maintain contracted power, it is necessary to shut off the power to the production equipment. Therefore, corresponding contacts SW ₁ , SW ₂ ... are provided for the loads LA ₁ , LA ₂ ... of the first group, so that even if the power is on, they are running idle (for example, there is nothing on the belt conveyor). If there are loads that are not actually used due to waiting time, etc., the operator manually closes the contacts corresponding to these loads.

When the control circuit 10 determines that the first group of loads must also be cut off, the control circuit 10 switches the contacts SW ₁ ,
Search whether SW ₂ ...etc. is closed. When a contact is closed, a cutoff signal is sent to the corresponding load to cut it off. in this case,
Even if the load is in the first group, it is not directly involved in production activities, so even if the load is cut off, productivity will not be affected. When the power consumption decreases, it is natural that the first group of loads should be powered on first. However, what should be noted in this case is that if it is clear that the waiting time is short, for example about 5 minutes, closing the contacts should be avoided. This is because performing on/off control in such cases only complicates the system and does not contribute much to load control.

As described in detail above, according to the present invention, it is possible to realize a load control method for a demand control device that can control power usage without affecting productivity.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram showing one embodiment of a demand control device for explaining the present invention. FIG. 2 is a diagram showing a demand curve. DESCRIPTION OF SYMBOLS 1... Electric energy meter with oscillator, 2... Current power counter, 3... Instantaneous power counter, 4... Clock generator, 5... Remaining time measuring circuit, 6... Multiplier, 7... Predicted power Arithmetic unit, 8... Target power computing unit, 9... Adjustment power computing unit, 10... Control circuit,
11...Load control signal generation circuit, SW ₁ to _{SW 2} ...
contact.

Claims (1)

[Scope of Claims] 1 Loads are divided into a first load group that is directly involved in production activities and a second load group that is not directly involved in production activities such as air conditioning equipment.
(a) when the regulated power is within the range of power that can be cut off, the on/off of the second load group is controlled; and (b) when the regulated power exceeds the range of power that can be cut off, In this case, all of the second load group is shut off, and only the loads in the first load group that are running idle or on standby are shut off, so that the power consumption during the demand period matches the target power. 1. A load control method for a demand control device, characterized in that: