JPH08126189A - Current differential protective relay system - Google Patents

Abstract

PURPOSE: To give priority to short-circuit even if a short-circuit undervoltage relay cannot be operated because a voltage drop is not enough when an accident occurs at a remote place. CONSTITUTION: Grounding accident detection condition include the operation of a self-end grounding overvoltage relay 7 and an other-end grounding overvoltage relay 20 and the non-operation of a self-end short-circuit undervoltage relay 6 and an other-end short-circuit undervoltage relay 21. When these conditions are all met, a logic circuit L outputs tripping command of grounding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current differential protection relay device which surely gives a short circuit priority regardless of the position of a fault point in a system which gives a short circuit priority in a ground fault of two or more phases. .

[0002]

2. Description of the Related Art In a current differential protection relay device used for a resistance grounding system, a large current equivalent to a short-circuit flows when a ground fault accident involving two or more phases occurs. Therefore, in order to prevent the ground fault current differential relay from improperly responding due to current transformer error, etc., a short circuit undervoltage relay with an interphase voltage is installed to provide a ground fault current differential in the event of two or more phases. The short-circuit priority method that locks the relay is applied.

FIG. 4 is a system diagram of a conventional resistance grounding system disclosed in, for example, Japanese Patent Application Laid-Open No. 2-95132, in which A and B are electrical stations, 1A and 1B are busbars, and 2 is three-phase. In the expression, a transmission line, 3 is a current transformer, 4 is a bus transformer, 5 is a current differential relay, 6 is a short circuit undervoltage relay, 7 is a ground fault overvoltage relay, and F is a ground fault accident point. Although not shown in the figure, it is assumed that the electric station B is also provided with the same relays as described above.

FIG. 5 is a block diagram showing a current differential protection relay device provided in an electric station A, and the electric device B is also provided with a similar device. In the figure, 5a is a ground fault current differential relay, 6 is a short circuit undervoltage relay, 7 is a ground fault overvoltage relay, 11 is an OR logic, 12 is a knot logic, and 13 is an AND logic.

Next, the operation will be described. First, in FIG. 4, when a two-phase ground fault of the AB phase occurs at a point F outside the distance to the power station A, the voltage at the power station A does not drop sufficiently due to the distance accident and a short circuit occurs. Undervoltage relay 6
May not work. In this case, the short circuit undervoltage relay 6 becomes inoperative in the trip block diagram of FIG. 5, and the output of the OR logic 11 of each phase output is at 0 level,
Therefore, the output of the knot logic 12 becomes 1 level.

Further, at this time, when a large current equivalent to a short circuit flows into the point F, the influence of the current transformer error at the electric stations A and B becomes remarkable, and the highly sensitive grounds provided at the electric stations A and B are detected. The current corresponding to the current transformer error flows as a difference current in the fault current differential relay 5a, and when the difference current exceeds the operation sensitivity, the ground fault current differential relay 5a malfunctions.

Therefore, in this case, the ground fault current differential relay 5a and the ground fault overvoltage relay 7 in FIG.
Moreover, since the output of the knot logic 12 is 1 level, all the inputs of the AND logic 13 are 1 level, and the trip command is output. As described above, the short circuit undervoltage relay 6
In the case of a distant accident that cannot operate, short circuit priority is not given, and there is a case where the local relays 5a and 7 cause a miss strip.

[0008]

Since the conventional current differential protection relay device is constructed as described above, the short circuit undervoltage is set as the trip lock condition by the local relays 5a, 7 for prioritizing the short circuit. Although the relay 6 is used, there are cases where the fault voltage drop at the relay ground point is not sufficient for a distant ground fault and the short circuit undervoltage relay does not operate as described above.

Therefore, when a short circuit is not prioritized and a difference current occurs due to a current transformer error due to a large current equivalent to a short circuit current during a multi-phase external ground fault, the highly sensitive ground fault current differential relay 5a operates. There was a problem such as a malfunction and a mistrip.

The invention of claim 1 has been made to solve the above-mentioned problems. Even when the short-circuit undervoltage relay does not operate due to insufficient voltage drop during a distant accident, An object of the present invention is to obtain a current differential protection relay device capable of giving priority to short circuit.

Further, the invention of claim 2 provides a current differential protection relay device capable of giving a short circuit priority to the operation of the ground fault overcurrent relay at its own end and the other end as a condition for establishing a trip command. With the goal.

Further, the invention of claim 3 provides a current differential protection relay device capable of giving a short circuit priority to the operation of ground fault distance relays at its own end and the other end as a condition for establishing a trip command. With the goal.

[0013]

A current differential protection relay device according to the invention of claim 1 is an operation of a ground fault current differential relay at its own end, and a ground fault at its own end as a ground fault accident detection condition. In a current differential protection relay that issues a trip command on the condition that the overvoltage relay operation and the short-circuit undervoltage relay operation at its own end do not work, the operation of the grounding overvoltage relay at the other end and the short-circuit at the other end A logic circuit is provided which allows the trip command when both the undervoltage relay malfunction and the above conditions are met.

Further, the current differential protection relay device according to the invention of claim 2 is the operation of a ground fault current differential relay at its own end,
In the current differential protection relay that issues a trip command on the condition that the operation of the ground fault overvoltage relay at the self-end as a ground fault accident detection condition and the malfunction of the short circuit undervoltage relay at the self end are conditions, A logic circuit is provided which permits the trip command when the operation of the overcurrent relay, the operation of the short-circuit undervoltage relay at the other end, and the above conditions are both satisfied.

Further, the current differential protection relay device according to the invention of claim 3 operates the self-ground fault current differential relay and the self-ground fault overvoltage relay as a ground fault accident detection condition. In the operation and the current differential protection relay device that issues a trip command on condition that the short-circuit undervoltage relay at its own end is inoperative,
A logic circuit is provided which allows the trip command when the operation of the ground fault distance relay at the other end, the operation of the short circuit undervoltage relay at the other end, and the above conditions are both satisfied.

[0016]

In the current differential protection relay device according to the present invention, the operation of the short-circuit undervoltage relay at the other end and the operation of the ground fault overvoltage relay are caused by the operation of the ground fault current differential relay at the self end. Since the ground fault detection condition is formed together with the operation of the ground fault overvoltage relay at its own end and the malfunction of the short circuit undervoltage relay at its own end, even if the voltage drop due to an accident is insufficient and the short circuit undervoltage relay fails. , Enable reliable ground fault detection.

Further, in the current differential protection relay device according to the present invention, the malfunction of the short circuit undervoltage relay at the other end and the operation of the ground fault overcurrent relay at the other end are set as one of the ground fault detection conditions. , Even if the short-circuit undervoltage relay at its own end becomes inoperable, the ground fault can be surely detected.

Further, in the current differential protection relay device according to the present invention, the non-operation of the short circuit undervoltage relay at the other end and the operation of the ground fault distance relay at the other end are set as one of the ground fault detection conditions. , Even if the short-circuit undervoltage relay at its own end becomes inoperable, the ground fault can be surely detected.

[0019]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 5a is a ground fault current differential relay at its own end, 6 is a short circuit undervoltage relay at its own end, 7 is a ground fault overvoltage relay at its own end, 11 is an OR logic, 12 is a knot logic, 13
Is an AND logic and these are the same as those shown in FIG. Further, 20 is a ground fault overvoltage relay at the other end, 21
Is a short-circuit undervoltage relay at the other end, 11a is an OR logic, 1
2a is a knot logic, 13, 13a and 13b are AND logics, and 1 is a transmission line. And these or logic 1
1, 11a, knot logic 12, 12a, and logic 1
3, 13a and 13b form a logic circuit L.

Next, the operation will be described. Now, consider a case where a two-phase ground fault occurs at a ground fault accident point F outside the electric power plant B as shown in FIG. 4 and the short-circuit undervoltage relay 6 of the electric power plant A does not operate. At this time, the short-circuit undervoltage relay 21 at the other end installed in the electric station B is close to the accident point, and thus can fully operate.

Therefore, the short-circuit undervoltage relay 21 at the other end
When OR operates, the OR logic 11a becomes 1 level and the output of the NOT logic 12a becomes 0 level. As a result, the output of the AND logic 13 is locked, and even if there is an improper response of the ground fault current differential relay 5a, the unnecessary trip can be reliably prevented.

Further, even if the reception of the operation signal of the short-circuit undervoltage relay 21 at the other end is delayed by the delay time in the signal transmission path, the transmission of the operation signal of the ground fault overvoltage relay 20 of the same terminal is also delayed. , There is no unnecessary permission signal for tripping. Thus, depending on the delay time,
The object can be achieved even when it is difficult to lock the trip command by the operation of the short-circuit undervoltage relay 21 at the other end.

Embodiment 2 FIG. In the above-described embodiment, the case where the ground fault overvoltage relays 7 and 20 are used as the ground fault detection relays is shown, but instead of these, it operates by detecting a ground fault overcurrent as shown in FIG. Ground fault overcurrent relay 8,22
May be used, and the same effect as that of the above-described embodiment can be obtained.

Example 3. Further, in the above-described embodiment, the case where the ground fault overvoltage relays 7 and 20 are used as the ground fault detection relay is shown. Instead of these, however, as shown in FIG. The distance relays 9 and 23 may be used, and the same effect as that of the above-described embodiment is obtained.

[0025]

As described above, according to the invention of claim 1, the operation of the self-ground fault current differential relay and the operation of the self-ground fault overvoltage relay as a ground fault accident detection condition, In the current differential protection relay device that issues a trip command on the condition that the short-circuit undervoltage relay at its own end does not operate, the ground fault overvoltage relay at the other end operates and the short-circuit undervoltage relay at the other end does not operate. Since the logic circuit that allows the trip command is provided when both the above conditions are satisfied, the short circuit is surely prioritized regardless of the system condition and the transmission delay time.
There is an effect that a device capable of outputting a normal trip command is obtained.

Further, according to the invention of claim 2, since the ground fault overcurrent relay and the short circuit undervoltage relay at the other end are added as one of the permissible conditions of the trip command, the ground fault overcurrent relay is added. There is an effect that a trip command in which a current is tripped can be output in the same manner as described above.

Further, according to the invention of claim 3, since the ground fault distance relay at the other end and the short circuit undervoltage relay at the other end are added as one of the permissible conditions of the trip command, the distance There is an effect that it is possible to output the trip command in the same manner as described above as the trip condition with the ground fault distance data having different sizes and different operation time limits.

[Brief description of drawings]

FIG. 1 is a block diagram showing a current differential protection relay device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a current differential protection relay device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a current differential protection relay device according to a third embodiment of the present invention.

FIG. 4 is a system diagram showing a conventional resistance grounding system.

FIG. 5 is a block diagram showing a conventional current differential protection relay device.

[Explanation of symbols]

 5a Ground fault current differential relay of its own end 6 Short circuit undervoltage relay of its own end 7 Ground fault overvoltage relay of its own end 8 Ground fault overcurrent relay of its own end 9 Ground fault distance relay of its own end 20 Ground fault overvoltage relay of the other end 21 Counter end short circuit undervoltage relay 22 Counter end ground fault overcurrent relay 23 Counter end ground fault distance relay L Logic circuit

Claims (3)

[Claims] 1. An operation of a ground fault current differential relay at its own end, which determines an operation amount by calculating a difference between detected current values at electric terminals at opposite ends, and a ground fault overvoltage at its own end as a ground fault accident detection condition. In the current differential protection relay device that issues a trip command on the condition of the operation of the relay and the inoperability of the short-circuit undervoltage relay at its own end,
Current difference characterized by the provision of a logic circuit that allows the trip command when the operation of the ground fault overvoltage relay at the other end, the operation of the short circuit undervoltage relay at the other end, and the above conditions are both satisfied Dynamic protection relay device. 2. The operation of a ground fault current differential relay at its own end, which calculates the difference between the detected current values at the electric terminals at opposite ends, and determines the operation amount, and the ground fault overcurrent at its own end as a ground fault accident detection condition. In the current differential protection relay device that issues a trip command on the condition of the operation of the relay and the inoperability of the short-circuit undervoltage relay at its own end,
Current difference characterized by providing a logic circuit that allows the trip command when the operation of the ground fault overcurrent relay at the other end, the operation of the short circuit undervoltage relay at the other end, and the above conditions are both satisfied Dynamic protection relay device. 3. The operation of a ground fault current differential relay at its own end, which determines the difference between the detected current values at the opposing end electrical stations as an operation amount, and the ground fault distance at its own end as a ground fault accident detection condition. In a current differential protection relay that issues a trip command on the condition that the relay operates and the short-circuit undervoltage at its own end does not operate, the operation of the ground fault distance relay at the other end and the short-circuit undervoltage at the other end A current differential protection relay device comprising a logic circuit which allows the trip command when both the non-operation of the relay and the above condition are satisfied.