Research On Hybrid HVDC Circuit Breaker Topology For Flexible DC Transmission System

High-voltage DC circuit breaker is one of the key equipment to ensure the safe and stable operation of flexible DC transmission system.The paper analyzes the working mechanism,research status and application characteristics of mechanical DC circuit breakers,solid state DC circuit breakers and hybrid DC circuit breakers.Aiming at the application requirements of flexible DC transmission systems and the shortcomings of ABB hybrid high-voltage DC circuit breakers,this paper proposes a current-limiting hybrid high-voltage DC circuit breaker topology,analyzes the working principle of the circuit breaker,and gives the current-limiting reactor.Parameter design methods for inductors,resistors,and metal oxide arresters(MOA)of current limiting devices.Secondly,a three-terminal flexible DC transmission system simulation platform was built at PSCAD / EMTDC.The effects of current-limiting reactors,current-limiting device inductance and resistance,and MOA voltage-limiting protection on the performance of current-limiting hybrid high-voltage DC circuit breakers were studied.Compared with other literature’s HV DC circuit breaker schemes.Finally,a small power principle prototype of the current-limiting hybrid high-voltage DC circuit breaker designed in this paper was built in the laboratory.The simulation of the rising process of the fault current by switching the load was carried out,and the experimental results were compared with the simulation results and verified.The effectiveness of current limiting hybrid DC circuit breaker current limiting device to suppress fault current is presented.Simulation and experimental results show that the current-limiting hybrid high-voltage DC circuit breaker designed with the current-limiting hybrid high-voltage DC circuit breaker topology and the current-limiting device inductance,resistance,and MOA parameter calculation methods designed in this paper can effectively suppress the fault current,and When the inductance of the current-limiting reactor is small,a good current-limiting effect is obtained,and at the same time,the fault can be quickly removed to reduce the configuration requirements for the MOA.