JPH04294012A - Disconnecting switch control circuit - Google Patents

Abstract

PURPOSE:To provide a stable disconnecting switch control circuit able to solve problems of insulation by providing a voltage detecting device detecting generator voltage after releasing parallel-circuit breakers and disconnecting a disconnecting switch on condition that the generator volatage is zero. CONSTITUTION:After detecting that generator voltage is zero by means of a voltage detection device 10 connected to a main circuit of a generator 5, an auxiliary contact 10a is closed to excite an auxiliary relay 11. Thereby, a disconnecting switch for a synchronous starting circuit is opened at a contact 11a of the relay 11 so that overlapping of step wave surge of a high frequency to be generated from the disconnection switch between poles of an opened parallel-circuit breaker 7 and the generator voltage can be prevented. Accordingly, deterioration in interpole insulation of the circuit breaker can be reduced and also the capacity of the circuit breaker can be reduced.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disconnector control circuit for safely opening a disconnector in a power system connected to a generator.

0003

2. Description of the Related Art FIG. 3 shows a general configuration of a power system to which a generator is connected. Figure 3 shows an example of the configuration of the main equipment of the synchronous start-up circuit of a pumped storage power plant, where 1 is the motor on the driven side, 5 is the generator on the drive side, and 2 is the voltage that steps down the system voltage to the voltage of motor 1. A main transformer 6 is a main transformer that boosts the voltage of the generator 5 to the grid voltage, 3 and 7 are electrically connected to the main transformers 2 and 6, respectively, and connect the motor 1 and the generator 5 to the grid. , a parallel circuit breaker that interrupts disconnection or fault current; 4, 4a, 8, and 8a are disconnectors for switching phases of the generator and motor operation; 9 is a circuit breaker that is closed when the motor 1 is started synchronously with the generator 6; The circuits 4 and 8 are closed when the electric motor is operating, and the circuits 4a and 8a are closed when the generator is operated.

FIG. 4 shows a tripping control circuit for the disconnector 9 for the synchronous starting circuit, and 7a is an auxiliary contact of the parallel circuit breaker 7, which closes when the parallel circuit breaker 7 is disconnected. . Moreover, 9a is a tripping coil of the disconnector 9 for the synchronous starting circuit.

In FIGS. 3 and 4, the synchronous start of the motor 1 is achieved by opening the phase switching disconnectors 8, 8a, and 4a and closing the circuit 4, and connecting the generator 5 and the motor 1 with the disconnector 9 and the parallel circuit breaker 7. I'm going. When the electric motor 1 starts and reaches a specified speed and the parallel condition is established, the parallel circuit breaker 3 is closed and the starting is completed. After that, the parallel circuit breaker 7 of the main circuit of the generator 5 is disconnected, and when the parallel circuit breaker 7 is disconnected, the auxiliary contact 7a of the parallel circuit breaker 7 is closed as shown in FIG. 4, and the synchronous starting circuit The tripping coil 9a of the disconnector 9 is excited, and the disconnector 9 is instantly disconnected from the line.

[0006]

[Problem to be Solved by the Invention] In this case, it is known that if the synchronous start-up circuit shown in FIG. This high frequency steep wave surge is applied between the poles of the disconnected parallel circuit breakers 7.

On the other hand, although the generator 5 is controlled to stop, the voltage of the generator 5 does not instantaneously become zero, but is applied between the poles of the disconnected parallel circuit breaker 7. Therefore, between the poles of the parallel circuit breaker 7, there is a high frequency steep wave surge from the disconnector 9 and a generator 5.
When the voltage of the generator 5 and the grid voltage are out of synchronization, the steep wave surge and the generator voltage are completely superimposed, and the maximum voltage between the poles of the parallel circuit breaker 7 is applied. A voltage difference may occur, which may lead to insulation problems between the poles of the circuit breaker.

The present invention has been made in consideration of the above problems, and provides a safe disconnector control circuit that can eliminate insulation problems by tripping the disconnector under the condition that the generator voltage becomes zero. is intended to provide. [Structure of the invention]

[0009]

[Means and effects for solving the problems] The present invention provides a voltage detection device that detects the generator voltage after the parallel circuit breaker is disconnected, and trips the disconnector under the condition that the generator voltage becomes zero. ,
This prevents the high frequency steep wave surge generated by the disconnector from being superimposed on the generator voltage and being applied between the poles of the open circuit breaker.

0010

Embodiment An embodiment of the present invention is shown in FIGS. 1 and 2. In FIG. 1, 10 is a voltage detection device connected to the main circuit of the generator 5, 10a is an auxiliary contact of the voltage detection device that closes when the generator voltage becomes zero, and 11 is a disconnection condition for the parallel circuit breaker 7. That is, the auxiliary relay is energized when the auxiliary contact 7a is closed and the auxiliary contact 10a of the voltage detection device is closed, and 11a is the auxiliary contact that is closed when the auxiliary relay 11 is energized.

As described above, in the system shown in FIG. 3, the phase switching disconnectors 8, 8a, 4a are opened, the motor phase switching disconnector 4 is closed, and the generator 5 and the motor 1 are connected to the synchronous start disconnector 9. When the motor 1 is accelerated to the specified speed and the parallel condition is established, the parallel circuit breaker 3 is closed and the start is completed, and under that condition, the generator 5
The parallel circuit breaker 7 of the main circuit of
When this circuit is applied, the voltage detection device 10 connected to the main circuit of the generator 5 detects that the generator voltage is zero, closes the auxiliary contact 10a, and excites the auxiliary relay 11.
As a result, the synchronous start circuit disconnector 9 is opened at the contact 11a of the auxiliary relay that is closed, so that the high frequency steep wave surge generated from the disconnector between the poles of the open parallel circuit breaker and the generator voltage Therefore, deterioration of the interpole insulation of the circuit breaker can be reduced.

[0012] The above explanation is applied to a synchronous startup circuit of a pumped storage power plant, but the present invention instantly disconnects the disconnector after disconnecting the circuit breaker of the circuit to which the generator is connected. Applicable to all circuits. That is, FIG. 2 shows another embodiment of the present invention, in which 12 is a time-limited relay, and after the circuit breaker is disconnected, the contact 12a is turned on after a certain time delay when the generator voltage becomes zero at the time-limited relay 12. The circuit is closed and the disconnector is disconnected, thereby making it possible to safely open the disconnector.

[0013]

[Effects of the Invention] As explained above, according to the present invention, the high frequency steep wave surge generated when the disconnector is opened is applied between the poles of the circuit breaker while being superimposed on the generator voltage. Therefore, the capacity of the circuit breaker can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a conventional system diagram of a synchronous startup circuit in a pumped storage power plant.

FIG. 4 is a diagram showing an example of a conventional disconnector control circuit.

[Explanation of symbols]

1... Electric motor, 2, 6... Main transformer, 3, 7... Parallel circuit breaker, 4, 4a, 8, 8a... Phase switching disconnector, 5... Generator, 9
... Disconnector for synchronous starting circuit, 10... Voltage detection device, 11...
Auxiliary relay, 12... time-limited relay.

Claims (1)

[Claims] 1. A voltage detection device that detects a generator voltage in a disconnector control circuit in which a circuit breaker and a disconnector are connected to a generator, and which disconnects the circuit breaker and then opens the disconnector;
A disconnector control circuit comprising a time-limited relay that enables the disconnector to be tripped a predetermined time after the detected voltage becomes zero.