Hybrid direct-current circuit breaker based on capacitor commutation

Abstract

The invention provides a hybrid direct-current circuit breaker based on capacitor commutation. The hybrid direct-current circuit breaker comprises an ultra-fast mechanical switch unit, an auxiliary semiconductor switch unit, a capacitor commutation unit and an energy absorption unit; the ultra-fast mechanical switch unit is connected with the auxiliary semiconductor switch unit in series, the capacitor current conversion unit is connected with the ultra-fast mechanical switch unit and the auxiliary semiconductor switch unit which are connected in series in parallel, and the energy absorption unit is connected with the capacitor current conversion unit in parallel; the capacitor current conversion unit provides a low-voltage branch for the ultra-fast mechanical switch unit and the auxiliarysemiconductor switch unit to ensure normal switching-on and switching-off of the ultra-fast mechanical switch unit and the auxiliary semiconductor switch unit when a short-circuit fault occurs in thesystem, and cuts off fault current by utilizing a self-switching-off function; and the energy absorption unit absorbs energy stored in an inductive element in the power system after the fault currentis cut off after the on-off fault. According to the hybrid direct current circuit breaker based on capacitor commutation, soft turn-off of fault current is achieved, energy storage of inductive elements of the system is small during turn-off, and turn-off of the fault current and energy absorption limitation of a lightning arrester can be achieved.

Description

technical field [0001] The invention belongs to the technical field of DC circuit breakers, and more specifically relates to a hybrid DC circuit breaker based on capacitive commutation. Background technique [0002] Since direct current transmission is an effective measure to solve the problem of connecting green renewable energy to the power grid, and has the advantages of long transmission distance and large transmission capacity, it has been widely used in countries all over the world. Due to the small impedance of the DC side of the DC transmission network, when a short-circuit fault occurs in the system, the fault current rises rapidly. If the fault is not removed in a short time, the AC circuit breaker on the converter side will operate, and the converter valve group will be blocked, affecting the entire system. Normal operation greatly reduces the reliability and flexibility of the transmission system. [0003] Therefore, it is very necessary to develop a DC circuit ...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the defects of the prior art, the purpose of the present invention is to provide a hybrid DC circuit breaker based on capacitive commutation, which aims to solve the technical problems in the prior art that the DC circuit breaker is difficult to break the fault current and the arrester has large energy absorption

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