JPH0321176Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an automatic load selection and disconnection device that selects and disconnects less important loads when disconnection occurs between the power purchasing system and private power generation system during parallel operation. It is something.

Conventionally, there have been devices of this type as shown in FIGS. 1 to 3. In the figure, 1 is the power supply power detector of the power supply system, 2, 3, 4, 5, and 6 are the load power detectors of the load group, 7 is the power adder of the load to be cut off when selecting the load group, and 8 is the power supply A power comparator 9 which compares the power value detected by the power detector 1 of the grid and the added power value of the selected load of the load group of the power adder 7 and the added power value of the load to be cut off, and outputs a difference power signal; is a selection command device that determines whether the difference power signal output from the power comparator 8 is large or small in power in the power supply system, and when the signal exceeds the dead band power, selects and instructs to increase or decrease the disconnection load. , 10 is a signal intensifier relay that is energized when the power of the power supply system is large and outputs a signal to increase the load to be selectively cut off, and 11 is a signal increaser relay that is energized when the power of the power supply system is small and outputs a signal to increase the load to be selectively cut off. a signal reduction relay device that outputs a signal to reduce the signal, 10
a is a signal increase contact that turns ON when the signal increase relay 10 is energized, 11a is a signal reduction contact that turns ON when the signal reduction relay 11 is energized, and 12 is a load to be selectively cut off. 13 is the first priority selective storage relay that is selectively stored in the second
The third selection storage relay 14, 15, 16
12th, 4th, and 5th selection memory relays
a, 13a, 14a, 15a, and 16a are selection signal contacts 12aT 1 that are turned on when each of the selection memory relays 12 to 16 receives a signal from the signal increaser contact 10a, and are turned off when they receive a signal from the decrease signal _11a.
~15aT ₁ is an increasing step signal contact 13 which is turned ON sequentially with a time delay when the selection storage relays 12 to 15 each receive a signal from the increasing signal contact 10a.
aT ₂ to 16aT ₂ are reduction side release signal contacts that are sequentially turned on with a time delay when the selection storage relays 13 to 16 each receive a signal from the reduction signal contact 11a;
Reference numeral 17 denotes a power supply series disconnection signal for the power source and disconnector, and 18 represents a load trip circuit for each load source and disconnector.

Next, the operation will be explained. Power supply power detector 1
The power signal detected at is input to the power comparator 8. Initially, since there is no power signal in the power adder 7, the selection command unit 9 operates the signal intensifier relay 10 to balance the load power with the power supply power, the signal intensifier contact 10a turns ON, and the selection memory relay 12
works. Then, the selection signal contact 12a is turned ON.
Then, the load power signal detected by the load power detector 2 is input to the power adder 7 and further output to the power comparator 8. The power comparator 8 compares the source power and the load power and outputs the result to the selection command unit 9.The selection command unit 9 compares it with the internal dead band power value, and if the power supply power is large, causes the signal amplifying relay 10 to continue operating. When the increasing signal contact 10a continues to be in the ON state, the increasing step signal contact _12aT1 becomes ON after a certain time period, and the selection storage relay 13 for the next load is activated. Next, the selection signal contact 13a is turned on, and the load power signal detected by the load power detector 3 is input to the power adder 7, added to the power signal of the load power detector 2, and output to the power comparator 8. Ru.

Therefore, the power comparator 8 compares the source power and the load power as before, and outputs the result to the selection command device 9, which compares it with the dead band power value provided internally. However, when the power source power is large, the operation of the signal amplifying relay device 10 is continued, and on the other hand, when it is equal to or smaller, the operation of the signal amplifying relay device 10 is stopped. When fluctuations in the power source power or load power occur and the balance is disrupted, the same operation is repeated to achieve power balance.

When the selected load power increases or the source power decreases, a signal indicating that the load power is large is output to the power comparator 8, and the selection command unit 9 operates a signal reduction relay to balance the load power with the source power. The device 11 is operated. Due to this operation of the signal reduction relay 11, the signal reduction contact 11a is turned on, and the selection storage relays 16 are reset in sequence, and the selection storage relay 13 stored first is reset. Then, the selection signal contact 13a turns OFF,
The load power signal detected by the load power detector 3 is excluded from the input of the power adder 7, and the load power input to the power comparator 8 becomes smaller. The results will be compared and output to the selection command unit 9. The selection command device 9 compares the dead band power value provided internally, and if the power source power is small, the operation of the signal reduction relay 11 is continued, and if it is equal or larger, the operation of the signal reduction relay 11 is stopped. become.

In this way, the load power is selected to match the power source power to create an equilibrium state, and system abnormalities occur.
When the power supply system is disconnected, the power supply disconnection signal 17 of the power supply that will be removed turns ON, and the selection signal contacts 12a to 16
The load trip circuit 17 selected at point a is immediately cut off, and the remaining power source and remaining load continue to operate stably.

Conventional automatic load selection and disconnection devices are configured as described above, so when comparing the power and issuing a selection command to the load, a dead zone of at least the load power of one circuit is provided, and the increase/decrease signal of the selection command is Hunting must be prevented, and if there is a large load, the selection is made accordingly, which has the disadvantage of having to load or cut off more power than is commensurate with the power supply.

This invention was made to eliminate the drawbacks of the conventional ones as described above.If there is a load to be cut off that is commensurate with the difference in power in a state where no selection command increase/decrease signal is output, the load will be cut off. It is an object of the present invention to provide an automatic load selection and disconnection device that can prevent unnecessary load and disconnection from occurring in a relief circuit and exclude the load from being subject to disconnection.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 4, reference numeral 19 denotes a relief load power adder that adds up each load power through a selection signal indicating whether or not to rescue the power of the load circuit that has become the target of selection and disconnection, and 20 denotes a relief load power adder. A rescue load power comparator 21 detects a possible rescue load power value by comparing the power signal of 19 and the difference power signal of the power comparator 8; A method is prepared to sequentially check whether or not the load can be rescued starting from the load with the lowest priority for shedding, and one of them is selected, and according to the selected method, the power of each load to be shunned and the power of the rescue load are compared. A relief method selector 22 calculates a relief load from the output of the relief method selector 21, a relief load command device 22 issues a relief load selection command based on the calculation result of the relief method selector 21, and 23 to 27 determine relief loads for each load circuit. A relief load selection relay device that outputs a selection signal of
23a to 27a are relief load selection relays 23 to 2
7 is the contact point of the relief load selection signal that is turned ON when 23b to 27 is activated.
b is a relief load selection signal b contact which turns OFF when relief load selection relays 23 to 27 are in operation.

The following is a method of finding a combination that minimizes the output of the relief load power comparator 20 based on the relief possible power signal from the relief load power comparator 20 and each cutoff target load power signal.

1 Confirm the selection of the method 2 Read the power value of the load to be selected 3 Sort the power value of the load to be selected 4 Select the circuit to be combined with the relief load 5 Adjust the power of the load to be selected so that the relief load power comparison signal is the minimum Perform combinatorial operations.

Further, a method for sequentially verifying whether or not relief can be performed starting from the load with the lowest priority for load shedding is as follows.

1 Confirmation of method selection 2 Reading the power value of the selected load 3 Reset the output to the relief load command device.

4. Compare the rescue load power comparison signal and the selected load power sequentially from the opposite direction of the priority of selective cutoff,
The power of the circuits that is less than the unbalanced difference power generated by comparing the power of the power supply system and the load power to be selectively cut off is sequentially added, and calculations are performed until the result of the comparison calculation becomes smaller than the minimum load circuit power value.

In the above configuration, the differential power detected by the power comparator 8 changes between a power value that is the same as or slightly larger than the dead band power value preset in the selection command unit 9. In addition, this dead band power value is set larger than the load power value of one circuit to prevent hunting, so if even one large load is applied,
Even if other loads are small, the dead band power value is large.

Therefore, the relief load power comparator 20 compares the difference power signal of the power comparator 8 and the power signal of the relief load power adder 19 to determine the rescueable power and outputs it to the relief method selector 21. Selector 2
1 describes a method for finding a combination that minimizes the output of the relief load power comparator 20 based on the relief possible power signal from the relief load power comparator 20 and each load power signal to be disconnected, and a method for determining whether or not the load can be disconnected. Methods are prepared to sequentially check whether the load can be relieved starting from the lowest priority load, one of them is selected, and the relief load is calculated and determined in accordance with the selected method.

The relief load command device 22 gives an operation command to the relief load selection relays 23 to 27 of each target load circuit based on the calculation result of the relief load from the relief method selector 21. And relief load selection relay 23-2
7 operates, the relief load selection signal contact 23a
~27a is turned ON, and the selected load power signal to be cut off is input to the relief load power adder 19, and the added power signal is output to the relief load power comparator 20, where it is again compared with the signal from the power comparator 8. The above operation will be repeated.

In the above embodiment, the power source power detector 1 is shown as having one circuit, but it may have multiple circuits.
There is no limit to the number of 27, as long as it is plural.

Further, although the relief method selector 21 selects and uses a method prepared in advance, it may be used alone as an individual method.

Furthermore, in the above embodiment, the case where the load to be selected and disconnected is selected from the one with the highest priority, but if the power source to be disconnected is the power source that continues to operate, the case where the load is selected from the one with the lowest priority. The same effect as in the above embodiment can be obtained.

As described above, according to the present invention, since a load interruption relief circuit is added, unnecessary load interruption can be prevented, and power fluctuations after load interruption can be reduced.

[Brief explanation of drawings]

Figures 1 and 2 are block diagrams of a conventional automatic load selection and disconnection device, Figure 3 is a trip circuit diagram of a conventional automatic load selection and disconnection device, and Figure 4 is an embodiment of the present invention. A block diagram of an automatic load selection and disconnection device. FIG. 5 is a trip circuit diagram of an automatic load selection and disconnection device according to an embodiment of the present invention. 1... Source power detector, 2-6... Load power detector, 7... Power adder, 8... Power comparator, 9
... Selection command device, 10 ... Signal increase relay device, 11
... Signal reduction relay, 12-16... Selection memory relay, 12a-16a... Selection signal contact, 12
aT ₁ ~ 15aT ₁ ... Increase side step signal contact, 13aT ₂
~16aT ₂ ...Reduction side release signal contact, 17...Power supply disconnection signal, 18...Load trip circuit, 19...
Relief load power adder, 20...Relief load power comparator, 21...Relief method selector, 22...Relief load command device, 23-27...Relief load selection relay device,
23a to 27a... Relief load selection signal a contact, 2
3b to 27b...Relief load selection signal b contact, and in the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Utility Model Registration Claim] (1) When disconnection occurs between the power purchasing system and private power generation system during parallel operation, less important loads may be replaced to match the power of the disconnected power system. In automatic load selection and disconnection, which switches on and off loads according to predetermined priorities, when an unbalance occurs between the power of the power supply system to be disconnected and the power to be disconnected from the load, select A relief load power adder that adds the selected load power to be cut off according to a selection signal indicating whether or not to rescue the power of the load circuit that has been cut off; a relief load power comparator for determining the salvageable power by comparing the difference power with the added value and the difference power signal which is the output of the relief load power adder; The present invention is equipped with a relief method selector that activates a load failure relief calculation for a load that is subject to power relief when the power is exhausted, and a relief load command device that excludes the load that is subject to power relief from the failure target according to the calculation result. Automatic load selection and disconnection device. (2) The above-mentioned relief method selector has a combination that minimizes the differential power after relief in order to match the differential power and detect the load to be cut off. The automatic load selection and disconnection device described in item 1. (3) The automatic load selection and shearing device according to claim 1, wherein the relief method selector sequentially compares loads starting from the lowest priority for shedding.