Research On The Ultra-fast Breaking Technology Of Hybrid DC Circuit Breakers For In The Urban Railway System

The DC traction power supply system is responsible for providing power for electric locomotives and other equipment.DC switchgear is an important component of DC traction power supply system,which provides guarantee for its safe and stable.At present,most DC circuit breakers in China are air circuit breakers produced by foreign companies.Its breaking speed is slow,and has serious ablation problems,which can not meet the needs of fast and stable removal of faults.In recent years,with the development of semiconductor technology,the hybrid DC circuit breaker with parallel connection of fast switch and power electronic components has emerged,which has the characteristics of highly current-passing capacity and arc-less.However,the highspeed interruption technology which affects its interruption speed and stability still needs further research.This paper analyzed the principle of hybrid DC circuit breaker,the main basic characteristics affecting the high-speed interruption performance of hybrid DC circuit breaker include: vacuum arc current transfer characteristics,short vacuum gap dielectric recovery characteristics and surge current capacity of IGBT.The influence of different current and circuit parameters is studied by setting up a low voltage DC circuit.The criterion for the success of current transfer of vacuum arc is obtained through theoretical analysis,and verified the theoretical formula of current transfer rate.The influence of vacuum dielectric recovery is studied and gained the mathematical description.The simulation parameters of IGBT are extracted,thus simulated the surge current capacity of IGBT in Saber and Silvaco TCAD.The experiment proves that IGBT can bear at least three times the rated current within 600 μs.Intelligent interruption strategy of hybrid DC circuit breaker is obtained based on the above characteristics.And designed an urban rail transit hybrid DC circuit breaker with rated 1.8kV/2.5kA,short-circuit breaking current of 10 kA and full breaking time within 2ms,and verified the high-speed breaking strategy by the prototype breaker.