JPS63242127A - Distribution system protection system - 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] [Industrial Application Field] The present invention relates to a power distribution system protection system, and particularly to a power distribution system suitable for protecting a power distribution system in which an auxiliary power source for a consumer is connected to a power distribution line along with a load. Concerning protection systems.

[Conventional technology]

Distribution line accidents can be broadly classified into line accidents and equipment accidents, but the majority of them are line accidents. Many of the causes of railway accidents are contact with trees and animals due to falling snow and strong winds. Therefore, even if a line accident occurs, if the primary distribution line is left without voltage, the arc will naturally extinguish and power can be retransmitted without any abnormalities.

As a method to protect the power distribution system from such line accidents, protective relay engineering (published by the Institute of Electrical Engineers of Japan, July 1980)
The method described in is known. For example, 6KV
Alternatively, as a protection method for a 20KV distribution line, as shown in Figure 7, a high voltage distribution line connected to the bus bar via a circuit breaker CB.

A current transformer CT and a zero-phase current transformer ZCT are installed, and a ground voltage transformer GPT is installed on the bus bar, and an overcurrent relay O
The overcurrent method opens the circuit breaker CB when a ground fault or short circuit is detected by the activation of the C9 ground fault directional relay DG, ground fault overcurrent relay OCG, and ground fault overvoltage relay OVG. A combination of electric current methods is known.

In any of these methods, after the line is cut off due to an accident,
As shown in Figure 8, accident section separation devices DM-1 to DM are installed at key points of distribution lines or exits of branch lines.
-4(Delayed Magnetic 5w1t
Generally, a re-closing method is adopted in which the circuit is re-closed after a certain period of time by channel).

For example, in FIG. 8, when a ground fault F occurs between fault section separation devices DM-3 and DM-4, the fault is detected by the substation's ground fault protection relay, and as shown in FIG. The circuit breaker CB is opened, and the fault section separation devices DM-1 to DM-4 are opened after a delay opening time Z. Then, after a certain reclose time (for example, 30 seconds), circuit breaker CB
When the circuit is reclosed, power is supplied to the distribution line, so that the fault section separation devices DM-1, which is closer to the substation, are re-energized in order after an operation delay time X. At that time, if the accident continues when up to the fault section separation device DM-3 immediately before the fault point is turned on, a ground fault occurs due to the ground fault overcurrent relay, overcurrent relay, etc. included in the switch in each fault section separation device. is detected, and each accident section isolation device is shut off again within the reclose lock time Y. Furthermore, after the re-closing time, the circuit breaker CB is closed again, and this time up to the accident section separation device DM-2 is turned on, and the accident section separation devices DM-3 and DM-4 remain cut off, excluding the accident section. Only healthy sections will be retransmitted.

[Problem that the invention seeks to solve]

The above conventional technology is based on a system configuration in which only loads are connected to the distribution line and there is no auxiliary power source for consumers. .

No consideration is given to the connection of consumer auxiliary power sources such as gas combined cycle power generators to the power distribution system.

It is conceivable that such new power sources will be installed in homes and offices alongside the existing power supply system from electric power companies, and when such auxiliary power sources for consumers are installed, these can no longer be considered a simple load. Furthermore, even if the installed capacity of the auxiliary power source is relatively small, ranging from a few kW to less than 2000 kW, if the auxiliary power source for consumers is installed together with the load in the distribution system, the magnitude and direction of the current in the event of an accident may be affected. It is expected that this will cause problems in determining the accident area. Furthermore, the voltage in the fault section does not necessarily become non-voltage after the interruption, and there is a possibility that the conventional protection method cannot reliably protect the system.

An object of the present invention is to provide a power distribution system protection system that can temporarily disconnect the power source from the power distribution system when an accident occurs in the power distribution system in which the power source coexists with the load.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system in which an auxiliary power source for a consumer is connected together with a load to a distribution line branched from a distribution bus through a circuit breaker in a distribution substation. In the distribution system, a grounding means for grounding the distribution system in response to the opening operation of the circuit breaker of the distribution substation, and a grounding means for grounding the distribution system in response to the opening operation of the circuit breaker of the distribution substation; This is a power distribution system protection system that includes a power source separation means for separating the power source from the power distribution line.

[Effect]

When a ground fault occurs in the power distribution system, the power distribution system is grounded in response to the opening of the circuit breaker at the distribution substation. That is, after the power supply from the distribution substation to the distribution system is cut off, a ground fault is intentionally caused in the distribution system, the fault is detected by the power separation means on the auxiliary power supply side, and the auxiliary power supply is disconnected from the distribution line.

This makes it possible to reliably distinguish between accident sections and healthy sections.
It is possible to reliably protect the power distribution system.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In Figure 1, from the distribution bus to the distribution substation circuit breaker CB
The fault section separation device DM-1 is installed on the distribution line branched through the
, DM-2, DM-3, and DM-4 are connected. The fault section isolation device DM-2 is equipped with a ground voltage transformer GPT-2.
, relay (relay) RY2. A consumer auxiliary power supply G2 is connected via a power supply separation means 20 including a switch GSW-2 and the like. A ground voltage transformer GPT3. riI closure G S
An auxiliary power source G3 is connected via a power source separation means 30 including W3.

As shown in FIG. 3, each power source separation means 20.30 includes a ground voltage transformer GPT, a ground fault current transformer OCT, a line current transformer CT, and a switch GSW.

Overcurrent relay oC2 consists of a ground fault overcurrent relay OCG, a ground fault undervoltage relay UVG, a timer TM, and an OR gate OR, and the switch GSW is opened by the output from the OR gate OR. Overcurrent relay o
C is activated when the line current exceeds the set current, earth fault overcurrent relay OCG is activated when the current to earth exceeds the set value, and earth fault undervoltage relay UVG is activated when the voltage to earth is below the set voltage. It is designed to operate when the

Further, an operation delay time T1 and a recovery time T2 are set in the timer TM, and the recovery time T2 is set to be longer than the time from when the circuit breaker CB recloses to when it closes again.

Further, an earthing switch ESW is provided between the circuit breaker CB and the fault section separation device DM-1 to ground the distribution line in response to the opening operation of the circuit breaker CB.

In other words, the earthing switch ESW intentionally causes a ground fault in the power distribution system when the power to the power distribution system is cut off by the circuit breaker CB.
It is designed to let you

In the above configuration, the accident section separation device DM-3 and the DM
If a ground fault occurs at point F between will be released. At this time, the grounding switch GSW is closed in response to the opening operation of the circuit breaker CB, and one end of the distribution line is grounded. As a result, each power supply separation means 20.30
In relay RY2., relay RY2. RY3 detects, and after the operation delay time Tl, switches GSW-2 and GSW-3 open,
Each auxiliary power supply G2. G3 are each separated from the distribution line, and the voltage of each distribution line becomes completely voltage-free.

After this, after a certain reclosing time has elapsed, each fault section isolation device is reclosed in order starting from fault section isolation device DM-1, but even if the voltage of the distribution line returns to the original voltage, The switch opening command due to the operation of the undervoltage relay UVG is activated by timer T.
Since the switch is maintained by M for the return time T2, both switches GSW-2 and GSW-3 are not closed during re-closing. Therefore, once the power supply G2. Once G3 is disconnected from the power distribution line, the procedure up to retransmission of power can be performed in the same manner as before. Therefore, the healthy sections are retransmitted one after another by re-closing, and the interconnection line of power source G2 is also connected to the fault section separation device DM-2.
The battery is charged from the substation side by closing the circuit. Overcurrent relay OC2 of relay RY2 is ground fault overcurrent relay OCG, which is switch G.
Since it is reset by opening SW-2, when the ground fault undervoltage relay UVG detects that the voltage of the distribution line exceeds the set value and returns after the reset time T2 of the timer TM, the switch GSW2 is closed. Power supply G2 is again connected to the distribution line.

On the other hand, the power supply G3 connected to the accident section is disconnected from the power distribution line by the switch ESW opening the circuit breaker BC and the closing of the earthing switch ESW.

And when the circuit breaker CB is reclosed, the fault section separation device DM-
The switch GSW3 is not closed even when the switch GSW3 is instantaneously operated, and the fault section separating device DM-3 is not closed even when the circuit is closed again. Therefore, the distribution line in the accident section connected to the power source G3 is maintained in a voltage-free state, and the switch GSW3 is not closed.

As described above, according to this embodiment, even if an accident occurs in a power distribution system where power sources and loads coexist, the power source can be separated from the system, so it is possible to reliably distinguish between faulty sections and healthy sections. This can prevent damage to distribution system equipment. In addition, since the accident section can be made voltage-free, the safety of restoration work can be ensured even in the event of a permanent accident. Furthermore, after all the power supplies in the fault system are disconnected after turning on the ground switch SW, the same re-closing system as in the conventional system can be provided, so that the power distribution system can be protected reliably and safely.

In the above embodiment, the earthing switch E is used as the earthing means.
Although we have described the system using SW, as shown in Figure 4, switches SWI and SW are installed in the accident section separation device DM.
A grounding switch including W2 is provided.

When opening and closing the fault section isolation device DM according to the re-closing means of the circuit breaker CB at the time of an accident, the switch SWI is set to the same open/close state as the fault section isolation device DM, and the switch SW2 is closed when the fault section isolation device DM is open; Even if the circuit is configured to be open when the circuit is closed, and one end of the switch SW2 is grounded, the same operation as in the previous embodiment can be achieved. That is, each section separated by the fault section separation device DM is sequentially cut off after an accident occurs, and is reliably maintained at the ground potential by the grounding switch of the fault section separation device DM. Therefore, relay RY2 of each power source separation means 20, 30. R
Grounding is detected by Y3.

Su L/-RY2. RY3 switch GSW2゜GS
By opening W3, the power supply G2. G3 can be disconnected from the power distribution line.

According to this embodiment, in the event of an accident in the power distribution system, each section divided by the fault section separation device DM is reliably grounded regardless of the operation of the circuit breaker CB, and the power supply connected to each section is cut off from the power distribution system. be able to.

Further, according to the embodiment, the switch GSW in the power distribution system is reclosed when the system voltage is restored when the fault system is reclosed. However, as shown in Figure 5, an accident occurred in the system below circuit breaker CB1 connected to the busbar, and the section surrounding the fault point was separated between fault section separation devices DM-1 and DM-2. After that, a method can be considered in which the fault section separation device DM-5, which is in the communication path with the healthy system below circuit breaker CB-2, is turned on and power is retransmitted between the fault section separation devices DM-2 and DM-3. In this case, the switch GSW indicates that the voltage on the grid side has been restored by the ground fault undervoltage am switch UVG.
, and the switch GSW can be reclosed by the procedure shown in FIG. In this case, even when the healthy section of the faulty system is connected to another system for recharging, the healthy section can be reclosed while the faulty system is reliably maintained at no voltage.

〔Effect of the invention〕

According to the present invention, when a fault occurs in the distribution system, a ground fault is forced to occur in the distribution system from the busbar to the '14WT distribution system, and the power is cut off from the distribution system. It is possible to reliably distinguish the area from a healthy section, and it is possible to reliably protect the power distribution system.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
3 is a specific configuration diagram of the power supply separation means, FIG. 4 is a configuration diagram of the accident section separation device, and FIG. 5 is a configuration diagram showing another embodiment of the present invention. FIG. 6 is an explanatory diagram of the operation of the apparatus shown in FIG. 5. FIG. 7 is a block diagram of the conventional example, FIG. 8 is an overall block diagram of the conventional example, and FIG. 9 is an explanatory diagram of the operation of the conventional example. CB...Breaker, ESW...Earth switch, DM-1
~DM-5... Accident section separation device, GSW, GSW2
゜GSW3...Switch, RY2. RY3...Relay. G2. G3...Power supply.

Claims (1)

[Scope of Claims] 1. In a distribution system in which an auxiliary power source for consumers is connected together with a load to a distribution line branched from a distribution bus via a circuit breaker at a distribution substation, the circuit breaker at the distribution substation is opened. A grounding means for grounding the power distribution system in response to the grounding operation, and a power source separation means for disconnecting the auxiliary power source from the power distribution line in response to an electrical signal from the power distribution line accompanying the grounding operation of the grounding means. A power distribution system protection system characterized by: 2. The system according to claim 1, wherein the grounding means is a grounding switch that grounds the distribution line on the lower side of the circuit breaker in conjunction with the opening operation of the circuit breaker in the distribution substation. distribution system protection system. 3. In the system described in claim 1, the grounding means is a grounding switch that is provided in a fault section separation device of a distribution line and grounds the distribution line in conjunction with the separation operation of the device. Features: Power distribution system protection system. 4. In the system set forth in claim 1, the power source separation means includes a relay that is activated by detecting grounding of the distribution line, and a switch that disconnects the power source from the distribution line by activation of the relay. A power distribution system protection system characterized by: 5. A power distribution system protection system according to claim 4, wherein the relay includes a timer that resets the switch after a certain period of time after the power distribution line is ungrounded. 6. A power distribution system protection system according to claim 5, wherein the timer recovery time is set longer than the re-closing time of a circuit breaker in a distribution substation.