A snubber circuit suitable for bidirectional series load commutation switch of hybrid HVDC circuit breaker

Abstract

The invention proposes a snubber circuit structure and control strategy suitable for a bidirectional series load commutation switch of a hybrid high-voltage direct current circuit breaker. One of the unidirectional buffer circuit structures includes a capacitor C1, IGBTs T1, T2, diodes D1, D2, D3, and resistors R1, R2. The collector and emitter of T1 are respectively connected to the cathode and anode of D1; one end of R1 is connected to the emitter of T1, and the other end is connected to S2; the collector and emitter of T2 are respectively connected to the cathode and anode of D2; One end is connected to the collector of T2, and the other end is connected to the collector of T1; the cathode and anode of D3 are respectively connected to the collector of T1 and the emitter of T2; one end of C1 is connected to the collector of T1, and the other end is connected to node S2 connected. The circuit control strategy includes the control of T1 and T2 when the hybrid high-voltage direct current circuit breaker is opened and closed. The invention has simple structure and control, and improves the quickness and reliability of the hybrid high voltage direct current circuit breaker.

Description

technical field [0001] The invention relates to a buffer circuit suitable for a bidirectional series load commutation switch (LCS) of a hybrid high-voltage direct current circuit breaker, belonging to the field of high-voltage direct current transmission. Background technique [0002] Voltage source converter based high voltage direct current (VSC-HVDC) based on power electronics technology has achieved vigorous development in large power grid interconnection and point-to-point power transmission due to its advantages of flexible power control and no commutation failure. Power transmission also provides a solution for the grid connection and consumption of rapidly developing new energy sources such as solar energy and wind energy with strong randomness. As one of the key technologies of DC transmission, HVDC circuit breakers are also the basis for the operation, control and protection of DC power grids. Hybrid HVDC circuit breakers are the most practical in HVDC systems bec...

AI Technical Summary

Problems solved by technology

The structure of the RCD circuit is simple, but during the opening process of the hybrid high-voltage DC circuit breaker, when the current-carrying branch switches to the solid-state main switch branch, the buffer capacitor will be discharged through the UFD, resulting in an increase in the breaking current of the UFD and a change in the separation time of the UFD contacts. Long, which reduces the quick action of the hybrid high-voltage DC circuit breaker; based on the improved buffer circuit of RCD, the discharge branch of the buffer capacitor through the UFD is removed, but after the hybrid high-voltage DC circuit breaker is opened, the buffer capacitor goes up. The residual voltage is high, which reduces the reliability of the hybrid high-voltage DC circuit breaker for multiple opening and closing actions in a short period of time

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