JPS6311027A - Power system 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] [Objective of the Invention] (Industrial Application Field) The present invention has a power reception bus that receives power from an electric power company and a private generation bus for a private generator, and operates these in parallel. The present invention relates to a power system control device.

(Prior Art) An example of a conventional system separation device will be explained with reference to FIG. P
is a large-capacity power source for an electric power company.

The power receiving equipment of the consumer is the power receiving breaker R1 and the transformer TR1.
, a transformer secondary breaker S1, a bus breaker B1, a private communication breaker G1, a private generator G, etc., and steady operation is performed by parallel operation of the electric power company's power supply P and the private generator G. , distribution line breaker LL, L2. L3. L
Power is supplied to loads A, B, C, and D via 4.

In such a power system, if power transmission from the power supply P stops due to an accident in the power supply P of the electric power company or the power receiving system of the consumer during parallel operation, the entire load of the consumer will be transferred to the private generator G.
will bear the burden. At that time, if the total operating load is greater than the output of the generator G, the private generator G will be overloaded, and the breaker G1 will be cut off by the overcurrent protection function.
The entire equipment stops.

Therefore, in order to prevent such a total power outage, the following configuration was adopted. Potential transformer P is installed at the incoming power supply point of the customer.
T ]-1 Protective device PR installed via current transformer CTI
I detects a stoppage of the power supply P and an accident in the consumer's power receiving system. In addition, an accident that occurs on the receiving bus BUSR side or on the private power generation bus BUSG side is caused by a protection device PR2 provided at the bus connection point between the private generator G and the power supply P of the power system via a voltage transformer PT2 and a current transformer CT2. Detect. If an accident is detected by these protection devices PR1 and PR2, the bus breaker B1 is cut off and at least the loads C and D balanced with the output capacity of the private generator G or in front of the receiving power supply! Loads A and B connected to jAB U S R
A total power outage of customer equipment was prevented by allowing one of the following to continue operating.

In addition, the load side of the distribution line breakers L1 to L4, for example, F1
When a fault occurs at a point, the protection device PRL1 connected to the distribution line via the current transformer CTLI and the protection device PR2 at the busbar contact point simultaneously detect the fault, but the fault is detected at the same time when the distribution line breaker L1 is Busbar connection breaker B1 than disconnection signal
A time delay circuit is configured so that the trip signal is output with a delay. This time delay circuit allows the distribution line breaker L1 to be tripped first to prevent the busbar connection breaker B1 from being tripped. Similarly, when the accident occurrence point is point F2 on the load side of the distribution line breaker L3 connected to the private bus BUSG, the distribution line breaker L3 is tripped. In this way, when an accident occurs, protective disconnection by the distribution line circuit breaker is ordered from the end on the load side based on the principle of protective disconnection coordination. Therefore, distribution line breaker L
If there is a circuit breaker below L1 to L4, the distribution line circuit breakers L1 to L4 generally require several hundred mm S E C or more from the occurrence of an accident due to protective shutoff coordination. This also applies when an accident occurs at the lower level near the circuit breaker L1 to L4, for example at the F1 point.
The following problems occur:

In other words, when a three-phase short circuit occurs on the load side of the distribution line breakers L1 to L4, the voltage of the buses BUSR and BUSG suddenly drops, causing a sudden drop in the output of the private generator G and a gradual change in frequency. do. Therefore, although it depends on the power supply characteristics of the electric power company, the characteristics of the private generator, the impedance of the system, etc., the phase difference between the electric power company's power supply P and the private generator G increases in proportion to the accident duration time. Therefore, as mentioned above, even if the distribution line breaker is cut off several hundred millimeters after the accident occurs, the electric power company's power supply P
In many cases, private generator G is in a state of tax control, and parallel operation is no longer possible, and in the worst case, the main circuit breaker of the grid (power receiving system, bus bar, private generator) is tripped, resulting in a complete shutdown. There was a risk of this happening.

Therefore, if an accident occurs during parallel operation, depending on the system status at that time, open the busbar connection breaker B1 or immediately open the generator connection breaker G1 to disconnect the private generator G. Parallel operation is now discontinued.

(Problem 1 to be solved by the invention) Here, one generator connection breaker G1 is opened and the private generator G
, the load borne by the private generator G must be borne by the power from the electric power company, and the amount of power will increase significantly.

Generally, electricity consumers enter into contracts with power companies to ensure that the power demand does not exceed the target value during a certain period of time, but when the above situation occurs, the power demand exceeds the target value. This may happen.

The purpose of the present invention is to predict changes in power demand due to disconnection of private generators from a parallel operation state, and control so that the power demand supplied from the electric power company after disconnection does not exceed the contracted power value. An object of the present invention is to provide a power system control device.

(Means for Solving the Problems) As shown in FIG. A busbar communication breaker B1 is provided between the private power generation bus BUSG connected via the communication breaker G1, and loads A, B, and C are connected from the respective buses BUSR and BUSG.

This relates to a control device 1 for an electric power system that supplies electric power to a power source D, and as shown in FIG. Under the condition that parallel operation is being performed, the total value of the power demand by the electric power company and the output power of the private generator is calculated, and based on this total value, the power demand value at the end of the power demand monitoring time period is predicted, and this prediction is made. A power demand monitoring means 8 that determines whether the value exceeds a scheduled target power, an excess determination output 81 of this power demand monitoring means 8, and disconnection of the private generator G from the private power generation bus BUSG. The load selective cutoff control means 8 selectively cuts off the load according to the conditions.

(Function) In the present invention, during parallel operation, the power demand monitoring means 8 calculates the total value of the power demand value from the electric power company and the output power from the private generator, and thereby determines the power demand at the end of the power demand monitoring time period. If the predicted power value exceeds the target value due to the disconnection of the private generator due to an accident, etc., the load selection is cut off to prevent the actual demand power from exceeding the target value. ing.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Note that the same reference numerals in each figure indicate similar objects. Second
The figure shows a power system to which an embodiment of the present invention is applied, and the conventional protection device PR at the busbar connection point in Figure 4 is shown.
2, the power system control device 1 of the present invention is provided. This includes the secondary output V of potential transformer PT2, current transformer CT2
and secondary output of CTa] -1+ 12, Demand power amount measuring device PC that measures the power demand amount supplied from the electric power company
The demand integrated power amount pulse output DEMP and the demand power monitoring time pulse output DEMt from T are respectively input.

FIG. 1 shows the configuration of the power system control device 1, which is realized by an arithmetic processing device such as a microcomputer. The figure shows three conversion circuits 2.2a,
3. Power flow (power) direction determining means 4, Generator power detecting means 4a, Fault direction detecting means 5, Grid disconnection point selecting means 7, Parallel state detecting means 6゜ Demand power monitoring means 8, Load selection cutoff control means 9 In addition, the contact signals Sla, Bla, and Gla of the transformer secondary breaker S1, busbar connection breaker B1, and private generator connection breaker G1 shown in FIG. 2, from the power demand measuring device PCT supplied by the power company. A demand integrated power amount pulse signal DEMP and a demand power monitoring time pulse signal DEMt are shown, respectively.

Conversion circuits 2 and 2a are configured to convert secondary currents i of current transformers CT2 and CTa.
This is an A/D conversion circuit that inputs the signal 12 and converts it into a digital signal 21. The conversion circuit 3 inputs the secondary power V of the potential transformer PT2 and converts it into a digital signal 3.
This is an A/D conversion circuit that converts the data into 1. The power flow (power) direction determining means 4 uses the digital signal 2 from the conversion circuits 2 and 3.
1 (corresponds to i).

31 (corresponding to v), the busbar connection breaker B in Fig. 2
The direction of electric power flowing through the sensor 1 is sampled at regular intervals, and a detected direction signal 41 is output. That is, the signal 41 is output when power is flowing in the direction from the private power generating bus BUSG to the power receiving bus BUSR.

The generator (G) power detection means 4a is the conversion circuit 2a.

Digital signal 21a (corresponding to i) from 3,
31 (corresponding to v), self-generated communication breaker G in Figure 2
1, the output power value of the private generator G is sampled at regular intervals, and the detected power value data 41a is output. The power flow (power) direction determining means 4 and the power detecting means 4a are activated by the output signal 61 of the parallel state detecting means 6. This parallel state detection means 6 is connected to contacts Sla and Bl that are closed when the transformer secondary breaker S1, busbar connection breaker B1, and private generator connection breaker G1 shown in FIG. 2 are closed.
Based on each input from a and Gla, it is detected that the electric power company's power supply P and the private generator G are in a parallel operation state, and a detection signal 61 is output.

The accident direction detection means 5 detects the direction in which the accident occurred based on the digital signals 21 (corresponding to I) and 31 (corresponding to V) output from the conversion circuits 2 and 3, and detects the direction in which the accident occurred. It operates when electric power is detected and outputs accident direction detection signals 51 and 52. Here, the signal 51 is output when reactive power flows toward the private generator @BUSG. Further, a signal 52 is output when reactive power flows toward the receiving poison gland BUSH.

The power flow direction determining means 4 and the generator power detecting means 4a are activated by the parallel state detection signal 61 from the parallel state detecting means 6, and are activated by the parallel state detection signal 61 from the fault direction detecting means 5.
1 or 52 is input, subsequent sampling is stopped and updates of the detection signal 41 of the power flow (power) direction and the detection data 41a of the output power value of the private generator G are locked. That is, after the accident occurs, the power flow (power) direction detection signal 41 and the detected data 41a of the output power value of the private generator G before the accident occur are continuously output. The power demand monitoring means 8 is activated by the parallel state detection signal 61 from the parallel state detection means 6, and monitors the power demand P of the electric power company.
The power demand is monitored in the power demand monitoring time range from the input time of the power demand monitoring time pulse signal DEMt from the CT to the input of the next time pulse DENi. The demand integrated power pulse DEMP and the private generator output power data 41a are sampled at regular intervals, and the current value of the demanded power based on the demand integrated power pulse DEMP is calculated for each period. Also, for each sampling period.

During the remaining power demand monitoring time after that point, assuming that the private generator G is stopped, the demand power value at the end of the demand power monitoring time period is predicted by adding the output power data 41a of the private generator G. Then, it is determined whether or not this predicted value exceeds the target power during the power demand monitoring time, and if the predicted value of the power demand exceeds the target value, a determination signal 81 is sent.
Output.

The judgment signal 81 is a warning signal that predicts in advance that the power demand from the electric power company will exceed when the private generator G is stopped. It is valid as data for performing the following settings. The system disassembly point selection means 7 selects the tidal flow (
Electric power) Direction signal 41 before the accident of direction utilization means 4
and the accident direction signal 51 of the accident direction detection means 5.
52, selects a disconnection point of the system based on the output signal 61 of the parallel state detection means 6, and outputs a cutoff signal 71,72.

That is, the self-generated communication breaker G is activated by the cutoff signal 71.
1 is tripped, and the busbar connection breaker B1 is tripped by the disconnection signal 72. Grid disconnection load selection cutoff control means 9
is the power demand excess judgment output 8 from the power demand monitoring means 8
1, disconnection of private generator G from private generator bus line BUSG,
That is, the load selection cutoff signal 91 is generated on condition that the cutoff signal 71 of the self-generated communication breaker G1 is input. This load selective cutting may be performed by a notification method such as setting priorities in advance.

The system disassembly point selection means 7 is configured to execute, for example, the flowchart of FIG. 3.

In FIG. 3, first, the power direction signal 41 (a detection signal indicating that power was being supplied in the direction of the receiving bus BUSR before the occurrence of the accident), the accident occurrence detection signal 51 (the signal indicating that power was being supplied to the receiving bus BUSR before the occurrence of the accident),
SG direction accident detection signal) or accident occurrence detection signal 52
(fault detection signal in the direction of power receiving bus BUSR), parallel operation detection signal 61 (detection signal when power company power supply P and private generator G are in parallel operation state), demand power excess judgment output 8
1 (determination signal for determining whether or not the demand power exceeds due to disconnection of the private generator G), and reads each of these input signals (step 2). Next, it is evaluated whether an accident has occurred based on the presence or absence of input signals st and sz (step ■).
. If neither of the accident occurrence signals 51 and 52 is input, the process returns to step (2). If either of the accident occurrence signals 51 and 52 is input, it is determined based on the parallel operation signal 61 whether or not the electric power company's power supply P and the private generator G are in parallel operation (step 2). As a result, if parallel operation is not performed (either the electric power company's power supply P or the private generator G is in operation), there will be no phase shift between the power supply P and the private generator G (either one (because it's driving)
Therefore, a predetermined time delay is performed in order to coordinate protection with the lower-order circuit breaker (step ■). after that.

If the accident has been resolved, the process returns to step ■, but if it continues, a trip signal 72 is output to the busbar communication breaker B1,
(Step ■■), return to step ■.

In addition, in the evaluation of step (2), if parallel operation is being performed, it is evaluated whether or not power was being supplied in the direction of the power receiving bus BUSR before the occurrence of the accident based on the presence or absence of the output signal 41 of the power flow direction determining means 4 (step (2)). .

In this step ■, the power direction before the accident is set to power receiving bus B.
If the direction is toward USR (determination of YES), a trip signal 72 is immediately output to the busbar communication breaker B1 (step ■
) to disassemble the system, then return to step ■.

That is, the fact that the power flow is heading toward the receiving bus BUSR before the accident occurs means that the amount of power generated by the private generator G is large and the power consumption by the loads C and D is small. In this state, the power consumption of loads C and D can be sufficiently covered by the private generator G alone, and even if the busbar connection breaker B1 is opened, the private generator G will not be overloaded.

Therefore, in this situation, immediately connect the busbar connection breaker B.
1 is opened to prevent the occurrence of weakening due to an increase in the phase difference described above due to the parallel operation state before the accident continuing for a long time. In the event of an accident itself, a (superior) breaker near the accident point will shut off the accident after a predetermined protection coordination time, and the accident will be removed from the system.

On the other hand, in the evaluation of step ■, if power was not being supplied to the receiving bus BUSR before the accident occurred (
No judgment), the accident occurrence signal 51 is detected from the accident direction detection 5.
．． 52 is output, it is evaluated whether or not the direction in which the accident occurred is in the direction of the privately generated bus line BUSG (step (2)).

In other words, in the parallel operation state, the power flow is
The fact that it is not suitable for UsR means that the power consumption between meals C and D is greater than the power generated by the private generator G, and as mentioned above, if you open the busbar connection breaker B1 and cut off the power supply from the receiving bus BUSR side. There is a strong possibility that private generator G will be overloaded. However, since it is necessary to immediately disconnect the parallel operating state, the location of the accident is determined in step (2) as described above, and the disconnection point is determined as follows according to the result of this determination.

In the judgment of this step ①, if the accident occurrence direction is towards the privately generated bus BUSR (determination of YES), the disconnection point is set as the privately generated communication breaker G1, and a trip signal is immediately output to the breaker G1 (step Q ) to disassemble the lineage. After this disconnection, it is determined whether the demand power exceeds the contract power (step 2), and if it does not exceed the contract power (YES determination), the process returns to step 2. After disconnection, if the demand power exceeds the contract power value (determination of No), the load selection cutoff signal 91 is output (
step [phase]), perform load selection cutoff, and return to step (■).

In this way, by opening the private communication breaker G1, the parallel operation state is disconnected, and an increase in the phase difference between the two power supplies can be prevented. In addition, the private generator G stands by until the no-load accident is removed.

It also monitors the excess of contract power due to disconnection of private generator G. The accident itself was caused by a breaker near the point of occurrence (upper level).
After a predetermined protection coordination time, it is shut off and removed from the system.

On the other hand, if the accident occurrence signal 52 is input in step ■ (determination of No), it is determined that an accident has occurred on the power receiving bus BUSR side, and a trip signal 72 is immediately output to the busbar connection breaker B1 (step ■). Then, disconnect the system and return to step ■.

In other words, the fact that the direction of the fault is toward the power receiving bus BUSR means that the system on the private generator fiBUsG side is healthy, and in order to separate the healthy system from the faulty system, open the bus breaker B1. Immediately disconnect the parallel operation state. In this case, there is a strong possibility that the private generator G will be overloaded.

It is necessary to prevent the private generator G from being overloaded by selectively cutting off the loads C and D using a load adjusting means (not shown) or the like. In the case of an accident itself, as in the case described above, a circuit breaker near the hot water area where the accident occurred will shut off the accident after a predetermined protection coordination time, and the accident will be removed from the system.

In any of the above cases, after the accident has been removed from the system, it is of course possible to turn on the breaker at the disconnection point and resume parallel operation as before.

Here, the details of the case where, after excluding the private generator connection breaker G1 in step O, it is determined whether the demand power exceeds the contract power (step 2) will be explained.

FIG. 4 is a graph for explaining a general prediction means that calculates average predicted power based on used power and elapsed time. The average predicted power is calculated from the amount of power used ΔP (KWH) per unit time Δt [hour]. Here, unit time Δ
t [time] is usually set to about 1 to 3 minutes (about 2 to 5 times the monitoring cycle) in order to reduce the influence on the average predicted power due to fluctuations in power usage and received power pulse generation. do. FIG. 4 shows a case where the private generator is disconnected at the elapsed time t2. At this time, the unit time Δt [time] For example, the value of the average predicted power P2 at twice the monitoring cycle, that is, 2t, is calculated based on the average power consumption for 2t before the self-ignition train, so after the self-ignition train , does not include predictions of rapidly increasing power demand.

The average predicted power P for the next cycle also becomes a value increased by 1/2 of the self-generated power, and the demand power P increases due to the self-ignition train. will be less than. FIG. 5 is a graph corresponding to FIG. 4 that shows the relationship between power consumption and elapsed time. In FIG. 5, demand predicted power amount Q at t2
2. Power consumption at t2 and predicted horizontal power P2 at t2
The demand predicted power amount Q at t3 is calculated from
It is calculated from the amount of power used at t and the average predicted power P3 at t.

Therefore, the amount of power Qa is significantly smaller than the amount of power Qa that should originally be predicted by the self-firing array.

In this way, with the general power demand monitoring method that only monitors the power demand from the power company, it is not possible to instantly predict the sudden increase in power demand during a self-fired line, and there is a delay of several minutes before the correct prediction is made. There is a strong possibility that the power demand will exceed the demand.

Therefore, in the present invention, the power demand by the electric power company and the power generated by the private generator are added, and it is predicted whether the total value of these exceeds the target value.

In this way, when the private generator is disconnected,
It is possible to instantly determine whether or not the demanded power exceeds the target value at the end of the demand, and it is possible to immediately take measures such as selective load cutoff, thereby making it possible to prevent the demanded power from exceeding the target value. 4. In the above explanation, while the private power generation equipment is running in parallel, predictions are made for each monitoring cycle based on the sum of the electric power company's power demand and the privately generated power. Forecasts are made only based on the power company's power demand, and when the private generator is disconnected,
The prediction may be made by adding the privately generated power immediately before that.

In addition, in the above explanation, it is assumed that the private generator is disconnected from the grid due to an accident on the load side, but the same applies if the private generator is disconnected from the grid due to a problem with the private generator itself. It is.

〔Effect of the invention〕

As described above, according to the present invention, when the private generator G is disconnected due to an accident while the electric power company's power supply P and the private generator G are operating in parallel, the demand power is reduced due to the disconnection. If it is predicted that the contracted power will be exceeded, the power demand excess can be prevented by issuing an output in excess of the demand power and performing load selective cutoff.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the power system control device according to the present invention, FIG. 2 is a configuration diagram of a power system to which the device in FIG. 1 is applied, and FIG. 3 is a system state shown in FIG. 1. FIG. 4 and FIG. 5 are graphs showing changes in power demand due to disconnection of private generators, and FIG. 6 is a system configuration diagram showing a conventional device. P...Electricity company's power supply equipment B1...Bus line connection breaker G1...Private generation connection breaker BUSR...Power receiving bus 13USG...Private generation bus 4...Power flow direction determination means 4a... - Generator power detection means 5... Accident direction detection means 6... Grid status detection means 7... Grid disconnection point selection means 8... Demand power monitoring selection means 9... Load selection and cutoff control means Agent Patent Attorney Noriyuki Chika Ken Yudo Wang Hou Hongbun Figure 1 Figure 2 Figure 3 Figure 4 (My evening page)

Claims (1)

[Scope of Claims] A bus connection or disconnector is provided between the power receiving bus that receives power from the electric power company's power supply and the private generation bus that connects to the private generator via the private connection or disconnector. , in the control device for an electric power system that supplies power from each bus to a load, a parallel state detection means for detecting that the electric power company's power source and the private generator are operated in parallel; The total value of the power demand from the electric power company and the output power of the private generator is calculated based on the condition that the power demand is set at the end of the power demand monitoring time period. demand power monitoring means for determining whether or not the power exceeds the power demand; and selecting or disconnecting the load based on the excess judgment output of the power demand monitoring means and the disconnection of the private generator from the private generation bus. A power system control device comprising load selection and disconnection control means for performing load selection and disconnection control.