JPH04244728A - Reactive power relay device - Google Patents

Abstract

PURPOSE:To eliminate unnecessary operations due to a wrong operating procedure or an abrupt change in load amount by only detecting reactive power flowing out to a commercial power system except the reactive power consumed by a load. CONSTITUTION:Received effective power RP and bus effective power GP detected by power detecting elements 18 and 19 are sent to effective power ratio discriminating elements 22 and 23 and the ratio of the power PR to the power GP is computed. The elements 22 and 23 respectively perform arithmetic operations on Inequalities I and II by using a set effective power ratio factor SETK and, when the inequalities hold, respectively send operation commands to a received reactive power operation detecting element 24 and bus reactive power operation detecting element 25. The element 24 and 25 respectively send signals to an output element 26 when Inequality III holds against a set reactive power operation value SETQ and when Inequality IV holds between a set load power phase angle value SET and the set reactive power operation value SETQ. The output element 26 outputs an operating signal when the element 26 receives either one of the signals.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention selects a system separation point according to the balanced state of power supply in a power system in which multiple power supply facilities are operated in parallel, and selects a system separation point when an abnormality occurs in the power system. The present invention relates to a reactive power relay device applied to a power system separation system that isolates power systems by interrupting points.

0003

[Background Art] In power receiving and substation equipment that is composed of complex power generation equipment and power distribution equipment, a system is used to detect faults in the commercial power system at high speed and separate the commercial power system and the power generation equipment power system. A separate protection system is adopted, and a reactive power relay device (hereinafter referred to as DRP) is used as a means of detecting accidents in commercial power supply systems.
(referred to as R) is provided.

FIG. 4 shows an example of a conventional power receiving and transforming equipment system diagram to which DRPR is applied. In FIG. 4, a commercial power source 1 is connected to a bus 6 via a circuit breaker 2, a generator power source 5 is connected to a bus 7 via a circuit breaker 4, and a bus 6 and a bus 7 are connected via a circuit breaker 3. As a result, the commercial power source 1 and the generator equipment power source 5 are operated in parallel, and the power to the load A and the load B connected to the bus bar 6 and the bus bar 7, respectively, is shared between the commercial power source 1 and the generator equipment power source 5. and supply it.

[0005] In such a configuration, when an abnormality occurs in the commercial power supply, the load Depending on the operating status of A and load B and the power supply amount (output) of the generator equipment 5, the separation point between the commercial power supply 1 and the generator equipment 5 is set in advance by the circuit breaker 2 or 3.
It is set to .

The DRPRs 11 and 12 detect the amount of reactive power flowing out to the commercial power supply system through the circuit breaker 2 and the circuit breaker 3, respectively. DRPR via
It operates when reactive power exceeding each set value of 11 and 12 flows out.

FIG. 5 shows an output circuit for the system separation signal, and when the circuit breaker 2 is set at the separation point, the setting switch 13-a is closed and the circuit 13-b is turned on.
is opened, and when circuit breaker 3 is set at the separation point, setting switch 13-a is opened and 13-b is closed, and a trip signal is sent to circuit breakers 2 and 3 according to the settings of these setting switches. is each operating contact 11 of DRPR11 and 12
-a and 12-a and each closing condition of the setting switches 13-a and 13-b are outputted by a series circuit.

Similarly, when power to load A and load B are both supplied from the generator 5, the circuit breaker 2 is set as the system separation point, and the power flows through the circuit breaker 2 to the commercial power supply 1. When the reactive power exceeds the set value of the DRPR 11, the circuit breaker 2 trips.

On the other hand, when power to load A is supplied from the commercial power supply 1 and power consumption to load B is supplied from the generator 5, the circuit breaker 3 is set as the system separation point, and the The reactive power flowing out to the power supply system (6 bus directions) is DPRP1
When the set value of 2 is exceeded, the circuit breaker 3 is tripped, and the commercial power source 1 and the generator 5 are separated from each other.

In the above configuration, the DRPRs 11 and 12 detect an abnormality in the commercial power supply system from the magnitude of reactive power flowing into the commercial power supply system.
The setting values of are usually set to the same value. However, when circuit breaker 2 is set at the system separation point, power to load A is supplied from generator 5 via circuit breaker 3, and reactive power consumed by load A is supplied via circuit breaker 3. Since the oil always flows out in the direction of the bus bar 6, the following problem occurs. (1) Reactive power at the grid separation point normally flows in from the commercial power supply side in the case of general loads, and the outflow itself is considered to be an abnormality in the commercial power supply system, so DRPR11,
12 are usually both set to relatively small values. On the other hand, when the circuit breaker 2 is set at the system separation point, the reactive power consumed by the load A flows out in the normal state, and therefore the DRPR 12 operates unstablely or continuously in the normal state. Therefore, if you make a mistake in adjusting the load amounts of load A and load B, or adjusting the output of the generator 5 and switching the system separation point, the system separation point will be set to the circuit breaker 3. There is a risk that the output of the generator 5 will flow out in the direction of the bus bar 6, causing the DRPR 12 to operate and causing the circuit breaker 3 to be erroneously shut off. (2) As mentioned above, if the DRPR operates unstable or continues frequently, there is a risk of wear of the contact portions and poor contact. (3) When the power consumption of load B and the output power of the generator 5 are balanced and operated in parallel with the commercial power supply 1, the circuit breaker 3 is set at the grid separation point, and the power consumption of load B and the output power of the generator 5 are balanced. Since the output power of the generator 5 is balanced, power will not flow out to the bus bar 6 via the circuit breaker 3 during normal operation, but if the power consumption of the load B is due to human operation or protective shutdown of the load. If the circuit breaker 3 is shut off, the shut off power will be consumed by the load A, so the power will flow through the circuit breaker 3 toward the bus bar 6, and the DRPR 12 will operate, causing the circuit breaker 3 to become unnecessary. leading to a blockage.

[0011]

[Problems to be Solved by the Invention] The present invention is directed to reducing reactive power flowing out in the direction of the bus bar 6 via the circuit breaker 3 depending on the balance state between the power consumption of the load A or the load B and the output power of the generator 5. To provide a reactive power relay device capable of solving the above-mentioned problem by detecting only the reactive power flowing out to a bus bar 6 direction via a circuit breaker 3 when a commercial power source 1 is abnormal without reacting to the problem. The purpose is to [Structure of the invention]

0012

[Means and effects for solving the problems] The present invention selects a system separation point to be cut off according to the balance of power supply in a power system in which a plurality of power supply facilities are operated in parallel, and also disables abnormalities in the power system. In a reactive power relay device for a grid separation system that detects a change in power and shuts off a selected grid separation point, a separation point passing active power detection means for determining active power and reactive power passing through each grid separation point; separation point passing reactive power detection means; cutoff separation point selection means for selecting a system separation point to be cut off by comparing the ratio of the active power passing through each separation point with a preset active power ratio coefficient; The load supply reactive power is estimated from the active power passing through the selected grid separation point and the preset power phase angle setting value of the load, and this is subtracted from the reactive power passing through the selected grid separation point. The device is equipped with a reactive power operation detection means that corrects the reactive power passing through the separation point and generates an operation signal when the corrected reactive power passing through the separation point exceeds a set value. This ensures that the system can be separated and shut off reliably.

[0013]

Embodiment An embodiment of the present invention is shown in FIGS. 1 and 2. FIG. 1 is a configuration diagram of a power system to which a reactive power directional relay device 14 of the present invention is applied, and FIG. 2 is an internal configuration diagram of the reactive power relay device 14 of the present invention. In addition, the input currents I1 and I2 and the input voltage V in FIG. 2 are input to the power receiving circuit breaker 2 and the bus circuit breaker which are input through the instrument current transformers 8 and 10 connected to the power receiving point and the bus in FIG. 3 and the system voltage inputted through the potential transformer 9.

The input currents I1 and I2 and the input voltage V are connected to analog/digital converters 15 and 1, respectively.
6, 17, and the power detection element 1
8, 19 and reactive power detection elements 20, 21. The power detection element 18 detects the received active power RP flowing in via the power receiving circuit breaker 2, and the power detection element 19 detects the bus active power GP flowing in the bus bar 6 direction via the bus circuit breaker 3, and detects reactive power. The element 20 detects the received reactive power RQ flowing out to the commercial power source via the power receiving circuit breaker 2, and the reactive power detection element 21 detects the bus reactive power GQ flowing toward the bus bar via the bus circuit breaker 3.

In FIG. 2, the received active power RP detected by the power detection element 18 and the bus active power GP detected by the power detection element 19 are sent to active power ratio determination elements 22 and 23, where the bus active power A ratio of received active power to GP is calculated.

Further, the active power ratio determination element 22 performs a comparison determination with a preset active power ratio coefficient SETK, and for example, when the following formula (1) holds, the received reactive power operation detection element 24 Sends an operation execution command DR to. SETK≧RP/GP...(1) Similarly, the active power ratio determination element 23 also performs a comparison determination with the preset active power coefficient SETK. For example, when the following formula (2) holds true, the bus bar The calculation execution command DB is sent to the reactive power operation detection element 25. SETK<RP/GP...(2) The received reactive power operation detection element 24 compares and determines the received reactive power RQ detected by the power detection element 20 with a preset reactive power operation set value SETQ, When the following formula (3) is satisfied, a motion detection signal R1 is sent to the output element 26. SETQ≦RQ (3) The bus reactive power operation detection element 25 also detects the bus active power GP and bus reactive power GQ sent from the power detection elements 19 and 21, respectively, and the preset load power phase angle setting. The operation detection value is calculated and compared from the value SETφ and the reactive power operation setting value SETQ, and when, for example, the following equation (4) is satisfied, the operation detection signal B1 is sent to the output element 26. SETQ≦GQ−(GPtanφ)…(4)
The output element 26 is configured as an OR circuit, and is connected to the received reactive power operation element 24 or the bus reactive power operation detection element 2.
When any of the operation detection signals No. 5 is sent, an operation signal as a reactive power directional relay device is output.

FIG. 3 shows an example of an operating characteristic diagram of the reactive power directional relay device 14 according to the present invention, and the LVA is as shown in FIG.
is the apparent power point consumed by load A in
The power of load A is composed of received active power RP and received reactive power RQ flowing from the commercial power supply 1 via the receiving circuit breaker 2 and bus active power G flowing from the generator 5 via the bus circuit breaker 3.
P and bus reactive power GQ.

Further, the operating characteristic line R1 shows the operating characteristic of the received reactive power operation detection element 24, and shows that the received reactive power RQ flowing out to the commercial power source 1 via the receiving circuit breaker 2 is equal to the preset reactive power. This indicates that the operation is performed when the operation setting value SETQ is exceeded.

An operating characteristic line B1 indicates an operating characteristic of the bus reactive power operation detecting element 25, in which reactive power GQ supplied from the generator 5 in the direction of the bus 6 via the bus circuit breaker 3 is detected by the load A. Reactive power consumed by (=GP×tan
φ) is greater than or equal to a preset reactive power operation setting value SETQ.

That is, regardless of the magnitude of the load, the reactive power consumed by the load is always excluded according to the preset load power phase angle set value SETφ and the active power GP of the load consumption. Similar to the received reactive power operation detection element 24, it is possible to always operate at a constant value with respect to the reactive power that flows out when an abnormality occurs in the commercial power supply system.

In addition, the active power ratio coefficient SETK is determined according to the supply sharing ratio of the active power consumed by the load A between the commercial power source 1 and the generator power source 5, and is used to ensure stable power supply to the generator system in the event of an abnormality in the commercial power source system. It is set in advance to perform reactive power detection at the most appropriate system separation point. That is, load A
If the generator 5 supplies most of the power to the load A, reactive power flowing out from the power receiving point is detected; conversely, if the commercial power supply 1 supplies most of the power to the load A, the bus is shut off. It acts to detect the reactive power flowing out from the device 6 to the commercial system.

[0022]

[Effects of the Invention] As explained above, according to the present invention, in detecting reactive power at any system separation point,
Since it is possible to detect only the reactive power flowing out to the commercial power system, excluding the reactive power consumed by the load, it is possible to detect the reactive power that flows out to the commercial power system, so it is easy to operate when adjusting the output of the generator 5 or the load power consumption, etc. and switching the system separation point. The risk of unnecessary operation of the directional reactive power relay device due to procedural errors or sudden changes in load is eliminated, and it becomes possible to more reliably detect the occurrence of abnormalities in the commercial system.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of a power system to which a reactive power relay device according to the present invention is applied.

FIG. 2 is a configuration diagram showing an embodiment of a reactive power relay device according to the present invention.

FIG. 3 is a diagram showing an example of the operating characteristics of the reactive power relay device according to the present invention.

FIG. 4 is a system diagram showing an example of a power system to which a conventional reactive power relay device is applied.

FIG. 5 is a circuit diagram showing an example of the operation of a conventional reactive power relay device.

[Explanation of symbols]

1...Commercial power supply, 2...Power receiving circuit breaker, 3...Bus bar circuit breaker, 4...
Generator circuit breaker, 5... Generator power supply, 6, 7... Bus bar, 8, 1
0... Instrument current transformer, 9... Instrument transformer, 11, 12... Reactive power relay, 13... System separation point setting switch, 14...
Reactive power relay device, 15, 16, 17... Analog/digital converter, 18, 19... Active power detection element, 20,
21... Reactive power detection element, 22, 23... Active power ratio determination element, 24... Received reactive power operation detection element, 25... Bus bar reactive power operation detection element, 26... Output element, 27... Active power ratio setting coefficient storage element, 28... Reactive power operation setting value storage element, 29... Load power phase angle setting value storage element.

Claims (1)

[Claims] [Claim 1] A grid separation point to be cut off is selected according to the power supply balance of a power system in which multiple power supply facilities are operated in parallel, and an abnormality in the power system is detected by a change in reactive power. In a reactive power relay device for a grid separation system that interrupts a grid separation point, a separation point passing active power detection means and a separation point passing reactive power detection means for determining active power and reactive power passing through each grid separation point, and the above-mentioned A cutoff separation point selection means for selecting a system separation point to be cut off by comparing the ratio of active power passing through each separation point with a preset active power ratio coefficient; The load supply reactive power is estimated from the power and the preset power phase angle setting value of the load, and this is corrected by subtracting it from the reactive power passing through the selected system separation point, and this corrected separation is performed. 1. A reactive power relay device comprising reactive power operation detection means that generates an operation signal when point-passing reactive power exceeds a set value.