Buffer circuit suitable for hybrid high-voltage DC breaker bidirectional parallel load commutation switch

Abstract

The invention brings forward a buffer circuit structure suitable for a hybrid high-voltage DC breaker bidirectional parallel load commutation switch, and a control policy. The circuit structure comprises capacitors C1p and C1n, insulation gate bipolar transistors T1p and T1n, diodes D1p to D3n and resistors R1p to R2n, wherein the collector electrode and the emitter electrode of the T1p are connected with the cathode and the anode of the D1p; one end of the R1p is connected with the emitter electrode of the T1p, and the other end is connected with a node S2; one end of the C1p is connected with the collector electrode of the T1p, and the other end is connected with the node S2; the R2p and the D2p are connected in parallel; the anode and the cathode of the D2p are connected with the cathode of the D3p and the collector electrode of T1p; the anode of the D3p is connected with a node S1; and another same buffer circuit structure is reversely connected in series between the node S1 and the node S2. The control policy of the circuit comprises control over the T1p and the T1n when a hybrid high-voltage DC breaker is disconnected and connected. The structure and control are simple, and the quick acting property and reliability of the hybrid high-voltage DC breaker are improved.

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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