JP2581553B2 - Distribution system protection system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a power distribution system protection system, and more particularly to a power distribution system suitable for protecting a power distribution system in which a load and an auxiliary power source for a customer are connected to a distribution line. Regarding protection system.

[Conventional technology]

Distribution line accidents are roughly classified into line accidents and equipment accidents, the majority of which are line accidents. Many of the causes of track accidents are tree and bird contact with lightning and strong winds.
Therefore, even if a line fault occurs, once the distribution line is set to no voltage, the arc is naturally extinguished and power can be retransmitted without any abnormality.

As a method of protecting the power distribution system due to such a line accident, there is a method called protection relay engineering (issued by the Institute of Electrical Engineers of Japan, July 1981)
Is known. For example, as a protection method for a 6KV or 20KV distribution line, as shown in FIG. 7, a current transformer CT and a zero-phase current transformer ZCT are connected to a high-voltage distribution line connected to a bus via a circuit breaker CB. And a ground voltage transformer GPT on the bus, overcurrent relay OC, ground fault direction relay DG, ground fault overcurrent relay OCG, ground fault overvoltage relay O
Circuit breaker when detecting ground fault and ground fault accident by VG operation
There is known an overcurrent method that opens a CB, combined with a ground fault direction relay method and a ground fault overcurrent method. In any of these systems, after the faulty line is cut off, as shown in FIG. 8, faulty section separators DM-1 to DM-4 ( Delayed
In general, a reclosing method of re-closing after a certain time by a magnetic switch has been adopted.

For example, in FIG. 8, the accident section separation device DM-3
When a ground fault F occurs between DM-4, the fault is detected by the ground fault protection relay of the substation, and as shown in FIG. 9, the circuit breaker CB is opened and the delay open time Z is reached. The accident section separation devices DM-1 to DM-4 are opened. When the circuit breaker CB is reclosed after a predetermined reclosing time (for example, 30 seconds), power is supplied to the distribution line, so that the faulty section separation device DM-1 near the substation is sequentially restarted after the operation delay time X. It is thrown. At that time, the accident section separator DM just before the accident point
-3, if the accident continues, the ground fault overcurrent relay included in the switch in each accident section separation device,
A ground fault is detected by an overcurrent relay or the like, and each faulty section separating device is shut down again within the reclosing lock time Y. Furthermore, after the re-closing time, the circuit breaker CB is reclosed again, and this time the accident section separator DM-2 is turned on, and the accident section separator
DM-3 and DM-4 remain shut off, and only the healthy section excluding the accident section is retransmitted.

[Problems to be solved by the invention]

The above-mentioned prior art is a method that is realized on the premise of a system configuration in which only a load is connected to a distribution line and there is no auxiliary power supply for consumers, and new energy sources such as solar power generation and wind power generation, fuel cells, electric power, No consideration is given to the connection of a customer auxiliary power supply such as a combined gas power generation system to the distribution system.

Such new power sources may be installed in households and offices alongside the existing power supply system from the power company. Cannot be regarded as a simple load. Also, even if the auxiliary power supply has a relatively small capacity of several KW to less than 2000 KW, if the customer auxiliary power supply is installed together with the load in the distribution system, the magnitude and direction of the current at the time of the accident Is changed, it is expected that it will hinder the determination of the accident section. Further, the voltage in the accident section does not necessarily become zero 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 distribution system protection system that can temporarily disconnect a power supply from a distribution system when an accident occurs in a distribution system in which a power supply coexists with a load.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a distribution system in which a customer auxiliary power source is connected together with a load to a distribution line branched from a distribution bus through a circuit breaker of a distribution substation,
Grounding means for grounding the distribution system in response to the opening operation of the circuit breaker of the distribution substation; and the auxiliary power supply from the distribution line in response to an electric signal of the distribution line accompanying the grounding operation of the grounding means. And a power supply separating means provided with a power supply separating means.

[Action]

When a ground fault or the like occurs in the distribution system, the distribution system is grounded in response to the opening operation of the circuit breaker in the distribution substation.
That is, after the power supply from the distribution substation to the distribution system is cut off, an intentional ground fault occurs in the distribution system, the accident is detected by the power supply separation means on the auxiliary power supply side, and the auxiliary power supply is disconnected from the distribution line. . As a result, the accident section and the healthy section can be reliably distinguished, and the distribution system can be reliably protected.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

In Fig. 1, the breaker CB of the distribution substation from the distribution bus
In the distribution line branched through
-2, DM-3 and DM-4 are connected. Accident section separation device
DM-2 has a ground voltage transformer GPT-2, relay (relay) RY
2, a consumer auxiliary power supply G2 is connected via a power supply separating means 20 including a switch GSW-2 and the like. Accident section separation device
Ground voltage transformer GPT3, switch G between DM-3 and DM-4
The auxiliary power supply G3 is connected via a power supply separation means 30 including SW3.

As shown in FIG. 3, the power supply separating means 20 and 30
Ground voltage transformer GPT, ground fault current transformer GCT, line current transformer
It consists of CT, switch GSW, overcurrent relay OC, ground fault overcurrent relay OCG, ground fault undervoltage relay UVG, timer TM, and OR gate OR.The switch GSW is opened by the output from OR gate OR. I'm going to do it. The overcurrent relay OC is activated when the line current exceeds the set current, and the ground fault overcurrent relay OCG
The relay operates when the current between the grounds exceeds a set value, and the ground fault undervoltage relay UVG operates when the voltage between the grounds falls below the set voltage. The timer TM has an operation delay time T1 and a recovery time T2 set therein.
T2 is set to be longer than the time from re-closing to re-closing of the circuit breaker CB.

Also, between the circuit breaker CB and the accident section separation device DM-1,
A grounding switch ESW that grounds the distribution line in response to the opening operation of the circuit breaker CB is provided. That is, the earthing switch ESW is a circuit breaker
It is provided to intentionally cause a ground fault on the distribution line when the power to the distribution system is cut off by the CB.

In the above configuration, the accident section separators DM-3 and DM-
If a ground fault occurs at the point F between 4 and 4, the fault is detected by a protective relay (not shown) at the substation, and after the fault removal time determined by the operation time of the protective relay and the circuit breaker CB, the breaker
CB is released. At this time, the grounding switch ESW is turned on in response to the opening operation of the circuit breaker CB, and one end of the distribution line is grounded. As a result, the relays RY2 and RY3 at the power supply separating means 20 and 30 confirm that the fault current exceeding the set value flows out through the link point with the distribution line due to the ground fault at point F and the grounding of the grounding switch ESW. Is detected, and after the operation delay time T1, the switch GSW-2,
GSW-3 is opened, the auxiliary power supplies G2 and G3 are separated from the distribution lines, and the voltage of each distribution line is completely zero.

After this, after a certain reclosing time elapses, the accident section separation device
Each fault zone separation device is reclosed in order from DM-1, but even if the voltage of the distribution line returns to the original voltage, the switch open command by the operation of the ground fault undervoltage relay UVG is issued by the timer TM. Therefore, the switches GSW-2 and GSW-3 are not closed during the re-closing because they are maintained during the return time T2. Therefore, once the power sources G2 and G3 are disconnected from the distribution line, the procedure up to retransmission can be performed in the same manner as in the related art. For this reason, the healthy section is sequentially re-transmitted by the re-closed circuit, and the link line of the power source G2 is also charged from the substation side by the closed circuit of the accident section separating device DM-2. Since the overcurrent relay OC and the ground fault overcurrent relay OCG of the relay RY2 are restored by opening the switch GSW-2, the ground fault undervoltage relay UVG detects that the voltage of the distribution line exceeds the set value, When the timer TM returns after the return time T2, the switch GSW2 is closed, and the power supply G2 is connected again to the distribution line.

On the other hand, for the power supply G3 connected to the accident section, the switch ESW opens the circuit breaker CB and the circuit breaker CB is opened with the closed circuit of the ground switch ESW.
Disconnected from distribution line. When the accident section separator DM-3 operates instantaneously when the circuit breaker CB is reclosed, the switch
GSW3 is not closed and accident section separation device when it is closed again
DM-3 is not thrown. For this reason, the distribution line in the accident section connected to the power supply G3 is maintained in a non-voltage state, and the switch GSW3 is not closed.

As described above, according to the present embodiment, in a system in which a power source is mixed with a load in a distribution system, even if an accident occurs, the power source can be separated from the system. It is possible to prevent the equipment of the distribution system from being damaged. In addition, since no voltage is applied to the accident section, the safety of restoration work can be ensured even in the event of a permanent accident. Further, after all the power supplies of the faulty system are disconnected after the grounding switch ESW is turned on, the same reclosing method as the conventional one can be provided, so that the distribution system can be protected reliably and safely.

In the above embodiment, the grounding switch ES is used as the grounding means.
As described in Fig. 4, a grounding switch including switches SW1 and SW2 is provided in the fault zone separating device DM, and in accordance with the reclosing means of the circuit breaker CB in the event of a fault, as shown in FIG. When opening / closing the accident section separator DM, switch SW1
To the same open / close state as the accident section separation device DM, and switch SW
2 may be configured to be closed when the accident section separating device DM is open and open when the accident section separating device DM is closed, and one end of the switch SW2 may be grounded in the same manner as in the above embodiment. That is, each section divided by the accident section separator DM is sequentially cut off after the occurrence of the accident, and is reliably maintained at the ground potential by the grounding switch of the accident section separator DM. Therefore, grounding is detected by the relays RY2 and RY3 of the power supply separating means 20 and 30, and the switches GSW2 and GSW2 are detected by the relays RY2 and RY3.
By opening GSW3, power supplies G2 and G3 can be disconnected from the distribution line.

According to the present embodiment, at the time of a distribution system accident, each section divided by the accident section separating 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 distribution system. be able to.

Further, according to the above-described embodiment, the switch GSW in the distribution system is reclosed due to the recovery of the system-side voltage during the switching of the accident system. However, as shown in FIG. 5, an accident occurred in the system below the circuit breaker CB1 connected to the bus, and the section surrounding the fault point F was separated between the fault section separators DM-1 and DM-2. Later, a method is conceivable in which the accident section separator DM-5 in the communication path with the healthy system below the circuit breaker CB-2 is inserted, and power is retransmitted between the accident section separators DM-2 to DM-3. In this case, the switch GSW detects that the system side voltage has been recovered by the ground fault undervoltage relay UVG, and
The switch GSW can be reclosed by the procedure shown in the figure. In this case, even when the faulty system is recharged by connecting it to a healthy section with another system, the faulty system can be reclosed between sound diagrams in a state where the faulty system is reliably maintained at no voltage.

〔The invention's effect〕

According to the present invention, when an accident occurs in the power distribution system, the power distribution system is cut off from the bus, a ground fault is forcibly generated in the power distribution system, and the power supply is disconnected from the power distribution system.
The accident section and the healthy section can be reliably distinguished, and the distribution system can be reliably protected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a diagram illustrating the operation of each part of the drawing, FIG. 3 is a specific configuration diagram of a power supply separation unit, FIG. 4 is a configuration diagram of an accident section separation device, FIG. 5 is a configuration diagram illustrating another embodiment of the present invention, FIG. 6 is an explanatory view of the operation of the apparatus shown in FIG. 5, FIG. 7 is a structural view of a conventional example, FIG. 8 is an overall structural view of a conventional example, and FIG. 9 is an operational explanatory view of a conventional example. CB: Circuit breaker, ESW: Ground switch, DM-1 to DM-5
… Accident section separation equipment, GSW, GSW2, GSW3 …… Switch, RY2, R
Y3 …… Relay, G2, G3 …… Power supply.

Claims (6)

(57) [Claims] 1. A distribution system in which a load and a customer auxiliary power supply are connected to a distribution line branched from a distribution bus through a circuit breaker of a distribution substation, in response to an opening operation of a circuit breaker of the distribution substation. Grounding means for grounding the power distribution system,
A power distribution system protection system, comprising: a power supply separating unit that disconnects the auxiliary power supply from a distribution line in response to an electric signal of the distribution line accompanying the grounding operation of the grounding unit. 2. The system according to claim 1, wherein the grounding means is a grounding switch for grounding a distribution line on a lower side of the circuit breaker in conjunction with an opening operation of the circuit breaker in the distribution substation. A distribution system protection system, characterized in that: 3. The system according to claim 1, wherein the grounding means is provided in a faulty line separation device for the distribution line, and is a grounding switch for grounding the distribution line in conjunction with the separation operation of the device. A distribution system protection system characterized by the following. 4. The system according to claim 1, wherein the power supply separating means comprises a relay which operates by detecting grounding of the distribution line, and a switch which disconnects the power supply from the distribution line by operation of the relay. A distribution system protection system characterized in that: 5. The distribution system protection system according to claim 4, wherein the relay includes a timer for returning the switch after a predetermined time after the grounding of the distribution line is released. 6. The distribution system protection system according to claim 5, wherein a return time of said timer is set longer than a reclosing time of a circuit breaker of a distribution substation.