JP2860740B2 - Grid connection protection detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system interconnection system for connecting a generator system and a load to a system bus with a reverse power flow via a circuit breaker via a circuit breaker. Related to the device.

[0002]

2. Description of the Related Art Generally, in order for a high-voltage customer to interconnect a private power generation facility such as a cogeneration system (hereinafter referred to as a private power generation facility) with a system bus, a system interconnection protection system as shown in FIG. There is a need to. In FIG.
1 is a system bus, and 2 is a generator driven by an engine (not shown). 3 is an automatic voltage regulator (hereinafter abbreviated as AVR) for controlling the voltage of the generator 2; 4 is a circuit breaker for connecting the generator to the local system; 5 is a circuit breaker for connecting the system bus to the local system; 7 is a load connected to the premises system, 8
Is an undervoltage relay, 9 is a frequency lowering relay, 10 is an overvoltage relay, 11 is an overcurrent relay, 12 is a directional ground fault relay, 13 is a reverse power relay, and is applied when there is no reverse power flow. Reference numeral 14 denotes a distribution substation, and reference numeral 15 denotes a transfer cutoff device, which is configured to release the circuit breaker 5 by a signal from the substation at the time of a system failure in the presence of reverse power flow. In addition, 16 and 17 are disconnectors.

In the system for interconnecting private power generation facilities configured as described above, when the following abnormality occurs, it is necessary to immediately disconnect the private power generation facilities from the system bus. (1) In the event of an accident on the premises of a cogeneration customer (2) In the event of a system bus, that is, an electric power system accident

As a method of detecting the state of an accident at the time of these accidents, it is usually detected by a protection device as shown in FIG. That is, when there is no reverse power flow, the overcurrent relay 11,
The directional ground fault relay 12, the reverse power relay 13, the frequency lowering relay 9 and the like detect an abnormality at the time of an accident in the private power generation facility or the premises system, open the circuit breaker 5, and disconnect from the system. On the other hand, when there is a reverse power flow, the above-described relays or the like may not be able to detect the disconnection of the substation circuit breaker when the system is abnormal, and therefore, the transfer interruption device 15 is provided in the dedicated line interconnection to provide protection. ing. If there is a reverse power flow, the high-voltage distribution system is connected to a dedicated line, but in that case, an expensive transfer cutoff device 15 must be provided.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a system in a premises without connecting an expensive transfer interruption device in a dedicated line connection in the case of reverse power flow. It is an object of the present invention to provide a system interconnection protection detection device capable of detecting a generator alone operation at the time of a side accident and disconnecting a premises system from a system bus.

[0006]

To achieve the above object, according to the solution to ## system interconnection protection detection apparatus of the present invention, reactive power setter for setting a reactive power flow from or generator to the load from the system bus to the system bus And a reactive power detection circuit for detecting the reactive power of the generator and the load, and a setting signal of the reactive power setting device and a detection signal of the reactive power detection circuit, which are always input from the system bus to the load or from the generator to the system bus. A reactive power control circuit for controlling the automatic voltage regulator of the generator so that the reactive power of the set value set by the reactive power setting device flows, and a system bus failure, and the system bus to the load or from the generator to the system. When the reactive power to the bus is lost, the control change amount of the generator that tries to keep the reactive power from flowing from the system bus to the load or from the generator to the system bus is determined and the failure of the system bus is detected. And, which is constituted from a comparison circuit for interrupting the circuit breaker for connecting the system bus and premises system.

[0007]

According to the system interconnection protection detecting device of the present invention, the reactive power set by the reactive power setting device, that is, constant constant reactive power, is supplied from the system bus to the load or from the generator to the system bus. Therefore, if the system bus fails and a power outage occurs, the reactive power supplied from the system bus to the load or from the generator to the system bus becomes zero, and the reactive power from the generator matches the reactive power of the load. I do. for that reason,
The generator acts to keep the reactive power flowing from the system bus to the load or from the generator to the system bus, and the deviation signal of the reactive power control of the generator becomes large. The circuit breaker that connects the bus and the premises system can be quickly disconnected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to a system diagram of a system interconnection system for private power generation equipment in FIG. In addition,
Those denoted by the same reference numerals as those in the conventional example of FIG. 2 have the same functions, and the description thereof will be omitted.

In FIG. 1, reference numeral 21 denotes a reactive power detection circuit for detecting the reactive power of the generator, and reference numerals 22 and 23 denote reactive power detection circuits for detecting the reactive power of the local loads 6 and 7. 24 from the system bus to loads 6 and 7, or
A reactive power setting unit 25 for setting reactive power flowing from the generator 2 to the system bus; and 25, a reactive power detection value of the generator 2 and the loads 6, 7 detected by the reactive power detection circuits 21, 22, 23, and the reactive power. A reactive power control circuit that receives the output of the setting unit 24 and outputs a control signal 25a to the AVR 3 that controls the voltage of the generator 2, and from the system bus to the loads 6, 7 or from the generator 2 to the system bus. The supplied reactive power is controlled to be the reactive power amount set by the reactive power setting unit 24. On the other hand, a deviation signal 25 b corresponding to the deviation between the reactive power setting signal calculated by the reactive power control circuit 25 and the reactive power detection signal is output to the comparison circuit 26. The comparison circuit 26 compares the level of the deviation signal 25b from the reactive power control circuit 25 with a set value, and when the deviation signal 25b becomes larger than the set value, shuts off the circuit breaker 5 that connects the local system and the system bus. doing.

Next, the operation of this embodiment will be described.
In the system interconnection system configured as shown in FIG. 1, when the premises load is large, power is supplied to the load from the generator 2 and the system bus 1, and when the premises load is light, the output of the generator 2 is the load 6, A so-called reverse power flow for supplying power to the system bus 1 is performed. The reactive power from the generator 2 is detected by the reactive power detection circuit 21, and the reactive power of the premises loads 6 and 7 is detected by the reactive power detection circuits 22 and 23 and input to the reactive power control circuit 25. The reactive power control circuit 25 has a connection from the system bus 1 to the loads 6 and 7, or
The signal of the reactive power setting unit 24 for setting the reactive power supplied from the generator 2 to the system bus 1 is also input. The detected and set values of these reactive powers are stored in the reactive power control circuit 25.
The output is input to the AVR 3 for excitation of the generator 2, and the excitation of the generator 2 is controlled by the AVR 3, and the system bus 1 to the loads 6 and 7, or the generator 2 to the system bus 1 Is adjusted so that the reactive power supplied to the reactive power setting unit 24 becomes a value set by the reactive power setting unit 24. At this time, the deviation of the reactive power control circuit 25, that is, the reactive power detectors 21, 22,
The deviation between the reactive power detection signals of the generator 2 and the loads 6 and 7 detected at 23 and the reactive power setting signal set at the reactive power setting unit 24 is always zero.

In the system interconnection system in which the reactive power is controlled as described above, if an accident occurs in the system bus 1 and a power outage occurs in the power system, the load from the system bus 1 to the load 6,
7, or the reactive power supplied from the generator 2 to the system bus 1 cannot be supplied. If reactive power is not supplied from the system bus 1 to the loads 6 and 7 or from the generator 2 to the system bus 1, all the reactive power required by the local loads 6 and 7 is supplied from the generator 2. here,
Looking at the case where the reactive current supplied from the system bus 1 to the loads 6 and 7 disappears, the reactive power control circuit 25 determines that the system bus 1
However, since the reactive power is not supplied from the system bus to the loads 6 and 7, the deviation signal 25 b of the reactive power control circuit 25 is increased. That is, the reactive power detector 21,
The deviation between the reactive power detection signals of the generator 2 and the loads 6 and 7 detected at 22 and 23 and the reactive power setting signal set by the reactive power setting unit 24 increases to the + side, and the comparison circuit 26
, The comparison circuit 26 outputs a cutoff signal to the circuit breaker 5 connecting the system bus and the local system, and the circuit breaker 5
Will be separated. Also, from the generator 2 to the system bus 1
When the reactive current supplied to the power supply disappears, the reactive power control circuit 25 increases the reactive power from the generator 2 to the system bus 1, that is, increases the voltage of the generator 2. However, since reactive power cannot be supplied from the generator 2 to the system bus 1, the deviation signal 25b of the reactive power control circuit 25 increases to one side, reaches the operation level of the comparison circuit 26, and the comparison circuit 26 Then, a shutoff signal is output to the circuit breaker 5 that connects the local system and the circuit breaker 5 is disconnected.

[0012]

As described above, according to the present invention, the output voltage of the generator is controlled so that constant reactive power always flows from the system bus to the load or from the generator to the system bus. From the system bus to the load that occurs when a bus failure occurs,
Alternatively, the system is configured to detect a change in the generator control signal for recovering the disappearance of the reactive current flowing from the generator to the system bus and to detect a failure of the system bus. Sometimes a power system stop can be detected based on the power information on the premises without receiving a signal from the distribution substation, so the power transmission circuit breaker between the receiving line sending circuit breaker and the private power generation facility customer receiving point circuit breaker can be detected. The power receiving point breaker can be quickly disconnected without providing an expensive transfer blocking device.

[Brief description of the drawings]

FIG. 1 is a system diagram of a system interconnection system for private power generation equipment according to an embodiment of the present invention.

FIG. 2 is a system diagram of a conventional interconnection system for private power generation equipment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... System bus, 2 ... Alternator, 3 ... Automatic voltage regulator, 4, 5 ... Breaker, 6, 7 ... Premise load, 8 ... Undervoltage relay, 9 ... Overvoltage relay, 10 ... Overvoltage relay, 11
... overcurrent relay, 12 ... directional ground fault relay, 13 ... reverse power relay, 14 ... distribution substation, 15 ... transfer interruption device, 1
6, 17: disconnecting switch, 21, 22, 23: reactive power detection circuit, 24: reactive power setting device, 25: reactive power control circuit,
26 ... Comparison circuit.

Claims (1)

(57) [Claims] 1. A protection detection device for a system interconnection in which a premises system connected to a generator and a load is connected to a system bus via a circuit breaker, wherein the system bus to the load or the generator to the system bus. A reactive power setting device for setting reactive power to flow, a reactive power detection circuit for detecting reactive power of the generator and the load, and a setting signal of the reactive power setting device and a detection signal of the reactive power detection circuit, A reactive power control circuit that controls the automatic voltage regulator of the generator so that the reactive power of the set value set by the reactive power setting device always flows from the system bus to the load or from the generator to the system bus; When a fault occurs and the reactive power from the system bus to the load or from the generator to the system bus disappears, power generation that tries to keep the reactive power from flowing from the system bus to the load or from the generator to the system bus A system interconnection protection / detection device, comprising: a comparison circuit that determines a control change amount of a machine, detects a failure of a system bus, and shuts off a circuit breaker that connects the system bus and a local system.