JPS6285632A - Protective relay - 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 [Field of Industrial Application] The present invention relates to a protective relay device that disconnects a circuit breaker with high sensitivity even in the event of a power transmission line accident when the circuit breaker is closed.

[Conventional technology]

In general, a distance relay inputs voltage and current from the power system, calculates the distance from the relay installation point to the fault point, and trips the breaker when the fault point is determined to be within the protected area.

Distance relays are usually equipped with a memory circuit that stores the voltage before the accident so that they can operate even if the voltage drops to zero due to a nearby accident. However, if the breaker is opened due to an inspection or an accident, and the input voltage to the distance relay is zero, the storage voltage of the memory circuit is also zero.

- If there is an accident near the breaker when the circuit breaker is turned on, the input voltage will remain zero and the memory circuit will not be able to perform its function, causing the circuit breaker to shut off or shut off. It becomes impossible to remove the device.

In order to solve this problem,
As described in the publication, in the event of a close point fault when the breaker is closed, an overcurrent relay is combined, and the breaker is instantaneously shut off by the AND condition of the output of the overcurrent relay and the breaker closing command. is taking.

[The problem that the invention attempts to solve]

To configure the above trip sequence, it is necessary that the settling current value IRY, which determines the operation of the overcurrent relay, is larger than the maximum load current value ratio flowing through the transmission line, and that the fault current value at the fault point is The condition is that the current value be larger than the setting current value IRY of the overcurrent relay.

That is, it is necessary to satisfy the relationship IF<IRY<IL. Here, the relationship IF>IRY is an absolute condition for the overcurrent relay to operate and provide protection at the fault current value I. Therefore, for a power transmission system where the back power supply capacity is small and the fault current value I is small, the settling current value IRY of the overcurrent relay must also be made small so that it can operate at this fault current value I. As a result of this, the relationship IRY<IL.

That is, the setting current value IRY of the overcurrent relay is the maximum load current value 1. Some power systems will have to become smaller. In this case, even if there is no fault due to the breaker closing, the overcurrent relay will be activated by the current flowing through the transmission line, and the AND condition between this output and the breaker closing command will be established, leading to erroneous shutoff and reliability. It was no longer possible to expect a reliable power supply.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a protective relay device which can prevent the above-mentioned problems and can trip a breaker with high sensitivity even in the event of an accident when the breaker is turned on.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention, as shown in FIG. Operation signal of relay 1.

The circuit breaker is tripped by the output signal of the AND circuit 3 which receives the operation signal of the undervoltage relay 2 which inputs the voltage of the power transmission line by the voltage transformer.

[For production]

Accident response when a circuit breaker is turned on will be explained with reference to FIG. 3, which shows a power transmission system equipped with a protective relay device. Breaker 4
When both A and 4B are open, breaker 4A
Insert. In this case, if an accident exists in the protection zone, the overcurrent relay 7A is activated.

If the fault exists at the nearby end, the voltage of the power transmission line where the potential transformer is installed will also be at a scheduled value close to zero, and the undervoltage relay 8A will operate. Therefore, the AND condition of these operations is satisfied, and the circuit breaker 4A is tripped.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. 3 is a diagram showing a power transmission system equipped with a protective relay device. The back power supplies 4A and 4B are connected to busbars 5A and 5B, respectively, and a breaker 6A is connected between these busbars 5A and 5B.
A power transmission system connected by power transmission 12 via 6B is configured. Power transmission line 1 equipped with these circuit breakers 6A and 6B
In order to input the current and voltage information of 2, each circuit breaker 6A
, 6B, instrument current transformers 7A, 7B are installed on the busbar side, and instrument transformers 8A, 8B are installed on the line side. On the A end side of the power transmission line 12, the distance relay 9A inputs current information of the power line from the instrument current transformer 7A, and inputs voltage information of the power line from the instrument transformer 8A. The overcurrent relay IA receives current and voltage information from the instrument current transformer 7A, and the undervoltage relay 2A receives current and voltage information from the instrument transformer 8A. Also on the B end side.

Similarly, the distance relay 9B, overcurrent relay IB, and undervoltage relay 2B input current and voltage information of the power transmission line through the instrument current transformer 7B and instrument transformer 8B. Under normal conditions, circuit breaker 6A is activated by the operation of distance relays 9A and 9B.

Perform tripping of 6B. However, the circuit breaker 6A, 6
B is open, and for a certain period of time after turning on one of the circuit breakers, for example circuit breaker 6A, the operation signal of overcurrent relay IA and undervoltage relay 2A are activated as shown in the trip sequence diagram in Fig. 2. The circuit breaker 6A is tripped by the output signal of the AND circuit 3A which inputs the operation signal of the circuit breaker 6A. In addition, in order to provide protection for a certain period of time T after the breaker is turned on, the operation signal of the off-delay timer 11A, which extends the breaker 6A closing command 10A for a period of time T, is also sent to the AND circuit 3.
Add to A. There is also a similar trip sequence on the B end side in which the signal in FIG. 2 is replaced with B. Usually, breaker 6A,
To input 6B, it is necessary to synchronize the respective mother a5A and 5B.

Therefore, which end is the breaker, for example, breaker 6A.
After charging the power line and charging the power line, connect this power line and bus bar 5.
A method is used in which the circuit breaker 6B at the other end is turned on by synchronizing the circuit breaker 6B.

First, we will explain how to respond to an accident when the circuit breaker is turned on.

With both circuit breakers 6A and 6B open, circuit breaker 6A is turned on. Off-delay timer IIA operates. At this time, if a fault exists on the line side, a fault current flows and the overcurrent relay IA is activated.

At the same time, if the fault exists at the nearby end, the voltage of the power transmission line where the instrument transformer 8A is installed will also reach a planned value close to zero, and the undervoltage relay 2A will operate. Therefore, the AND conditions of these operations are satisfied, and the AND circuit 3A outputs a signal for external use of the circuit breaker 6A.

Next, a case will be described in which there is no fault when the circuit breakers 6A and 6B are turned on and a load current flows through the transmission line.

Now, with both circuit breakers 6A and 6B open, turn on circuit breaker 6A on the A end side. Off-delay timer IIA operates. At this time, since the breaker 6B on the B end side is open, no load current flows and the overcurrent relay current IA does not operate. Therefore, the AND condition is not satisfied and the breaker 4A is not tripped.

Thereafter, the power transmission line is charged and synchronized with the bus bar 5B at the B end, and then the circuit breaker 6B is turned on. Off-delay timer I
IB works. At this time, load current begins to flow. If the set value of the overcurrent relay IB is set to be smaller than this load current due to the request for high sensitivity detection, the overcurrent relay IB operates.

However, since the A-terminal breaker 6A has already been turned on, voltage is applied to the power transmission line, and the undervoltage relay 2B does not operate. therefore.

Since the AND conditions for these operations are not satisfied, the AND circuit 3B does not output a tripping signal for the circuit breaker 6B.

Therefore, even in power transmission systems where overcurrent relays are operated by the load current of the transmission line, it is possible to prevent unnecessary tripping of the breaker due to the load current when the breaker is turned on, and to ensure that the breaker is tripped in the event of an accident. We can provide a protective relay device that can be removed.

The same effect can be achieved not only by the above explanation but also by modifying the logic circuit that satisfies the same conditions.

〔Effect of the invention〕

In the present invention, the breaker exception is performed by the AND condition of the operation of the overcurrent relay and the operation of the undervoltage relay that inputs the voltage from the instrument transformer installed on the line side of the breaker. To provide a protective relay device which is unaffected by current and enables reliable external use of a breaker in case of an accident at the time of turning on.

[Brief explanation of drawings]

1 and 2 are diagrams showing a trip sequence of a protective relay device, and FIG. 3 is a diagram showing a power transmission system equipped with a protective relay device. 1... Overcurrent relay 2... Undervoltage relay 3.
...AND circuit 6A, 6B...breaker 7
A, 7B...Instrument current transformer 8A, 8B...Instrument transformer 9A, 9B...Distance relay 10A...
- Breaker closing command 11A...Off-delay timer representative Patent attorney Noriyuki Chika Yudo Hirofumi MitsumataFigure 1Figure 2Figure 35

Claims (1)

[Claims] In a protective relay system that uses a potential transformer installed on the line side of the breaker, for a certain period of time after the breaker is turned on, the overcurrent relay operates and the potential transformer inputs the voltage of the transmission line. A protective relay device characterized in that the breaker is tripped by an AND condition with the operation of an undervoltage relay.