A snubber circuit suitable for bidirectional parallel load commutation switch of hybrid high-voltage DC circuit breaker

Abstract

The invention proposes a buffer circuit structure and a control strategy suitable for the bidirectional parallel load commutation switch of the hybrid high-voltage direct current circuit breaker. The circuit structure includes capacitors C1p and C1n, insulated gate bipolar transistors T1p and T1n, diodes D1p to D3n, and resistors R1p to R2n. The collector and emitter of T1p are connected to the cathode and anode of D1p respectively; one end of R1p is connected to the emitter of T1p, and the other end is connected to node S2; one end of C1p is connected to the collector of T1p, and the other end is connected to node S2; R2p is connected in parallel with D2p; the anode and cathode of D2p are connected to the cathode of D3p and the collector of T1 respectively; the anode of D3p is connected to node S1; another identical buffer circuit structure is connected in reverse series between nodes S1 and S2. The circuit control strategy includes the control of T1p and T1n when the hybrid HVDC circuit breaker is opened and closed. The invention is simple in 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 parallel 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 b...

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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