Circuit for preventing malfunction of bus voltage parallel circuit

Abstract

The invention discloses a circuit for preventing malfunction of a bus voltage parallel circuit, and the circuit comprises a QK change-over switch, an isolation switch 1G auxiliary contact, an isolation switch 2G auxiliary contact, a circuit breaker FDL1 auxiliary contact and a PT parallel relay BLJ, wherein one end of the QK change-over switch is connected with a positive power supply; the other end of the QK change-over switch is connected with one end of the isolation switch 1G auxiliary contact, the other end of the isolation switch 1G auxiliary contact is connected with one end of the circuit breaker FDL1 auxiliary contact, and the other end of the circuit breaker FDL1 auxiliary contact is connected with one end of the isolation switch 2G auxiliary contact. The other end of the isolation switch 2G auxiliary contact is connected with one end of the PT parallel relay BLJ, and the other end of the PT parallel relay BLJ is connected with a negative power supply. According to the invention, when the bus PT is located at the parallel position for the second time, the opening operation loop of the sectional circuit breaker is effectively prevented from being locked.

Description

technical field [0001] The present invention relates to the technical field of electric power system protection, and more specifically, relates to a circuit for preventing malfunction of a bus voltage parallel circuit. Background technique [0002] Potential transformer, referred to as PT, is a special transformer used to measure the high voltage of the power grid. It can convert the high voltage into a lower voltage according to the specified ratio, and then connect it to protection, measurement and control, safety devices, instruments, meters and other devices. to collect or measure. For voltage transformers, no matter how many volts the primary side voltage is, the secondary side voltage is generally specified as 57.7 volts or 100 volts to supply the voltage required by the voltage coils of automatic devices such as related meters and relay protection. The primary actual conversion value is reflected by the secondary voltage change of the voltage transformer; the voltage...

AI Technical Summary

Problems solved by technology

[0010]① There is no mandatory locking measure for the parallel start-up circuit of the busbar voltage. Defects, the operation situation that does not conform to the "parallel bus PT or release of normal operation procedures" often occurs, which brings hidden dangers to the safe and stable power supply of the power system;

[0011]②When the secondary circuit of the busbar voltage is in parallel state, there is no mandatory blocking of the tripping circuit of the corresponding bus coupler or segmental interval circuit breaker. When the tripping pressure plate is opened, there is a system fault that first disconnects the primary parallel circuit, and then disconnects the secondary parallel circuit of the bus voltage, and there is a risk of short-circuit current burning the secondary equipment and the circuit

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