真空与气体一体化串联机械开关及其直流快速转移应用OA北大核心CSTPCD

The hybrid DC circuit breaker(DCCB)is the key equipment for the control,protection and isolation of DC system.Among them,the natural commutation method relying on vacuum arc voltage has a simple structure,but the commutation performance does not meet the demand of large current interruption.Forced commutation requires additional transfer devices to increase system complexity and cost.Combined with the idea of vacuum and gas medium series cooperative breaking in the previous research of the team,a series-connected vacuum and gas interrupters is proposed in this paper.The arc voltage of the mechanical switch can be increased to several hundred volts by series-connected vacuum and gas interrupters.This switch is applied to medium voltage hybrid DC circuit breaker to accelerate current transfer,giving full play to the advantages of high gas arc voltage and fast recovery of vacuum medium. Firstly,the topology of a new hybrid DC circuit breaker based on series-connected vacuum and gas interrupters(Novel-DCCB)is introduced,and the working principle of the structure is analyzed.Based on the continuous transient vacuum arc model,Mayr gas arc model,power electronic device model,buffer circuit model and arrester model,a simulation model of a novel hybrid DC circuit breaker based on vacuum and gas integrated series is built in Matlab/Simulink.The breaking waveforms of the whole machine are simulated and compared.Novel-DCCB shortens the current transfer time from 1900 μs to 300 μs by increasing the arc voltage of the mechanical switch.The TIV at both ends of HSS after IGBT shutdown is mainly borne by the vacuum gap.The advantages of high gas arc voltage in the arcing stage and fast recovery of vacuum medium in the TIV stage of HSS are fully utilized.Finally,the simulation analysis shows that the transfer limit current of Novel-DCCB can reach 100 kA,and the transfer time is basically controlled within 0.5 ms. Then,a series-connected vacuum and gas interrupters prototype(HSS)was built,and its opening principle was introduced and tested.Under the influence of the double over-range linkage operating structure,the gas gap and the vacuum gap were separated successively,and the time interval was about 200 μs.Finally,the HSS arc voltage characteristic experimental platform and HSS high frequency TIV withstand voltage experimental platform were built.The effects of contact structure,contact material,gas medium and air pressure on the arc voltage characteristics were tested.The contact material was W70Cu,the contact structure was bridge type two contact,the gas type was hydrogen nitrogen mixed gas(H2:N2=2:3),the air pressure was 0.3 MPa,the gas arc voltage could reach 96 V,and the total HSS arc voltage could be increased from 20 V to 120 V;the static voltage distribution and insulation strength of HSS high-frequency TIV were tested.The results show that the partial pressure of HSS high-voltage side vacuum interrupter accounts for 55%under high-frequency TIV,and the maximum tolerance TIV of HSS is 20 kV.