超导限流器与机械式直流断路器的全电流开断配合方法

Full-range Currents Interruption Methods by Coupling Current Injection DC Circuit Breakers with Superconducting Fault Current Limiters

目前机械式高压直流断路器开断小电流过程中,真空开关需要承受极高的di/dt、额定电流,小容量短路电流开断难度大。为此,提出了一种改进的超导限流器与机械式高压直流断路器全电流开断配合方法,依托电阻型超导限流器独特的失超特性,利用超导限流器的失超电压为机械式直流断路器的谐振电容进行短路电流适应型充电,针对不同范围的电流开断,真空断路器可提供灵活变化的反向电流,大幅降低了机械式直流断路器开断小电流时承受的di/dt,提高了其全电流范围开断的可靠性。首先介绍了机械式直流断路器与超导限流器配合的拓扑结构与配合原理,然后在200 kV直流电路中建立了拓扑结构的数学模型,分析了小电流和30%、60%额定阶段电流开断过程。仿真表明,进行30%额定阶段电流开断时,机械式直流断路器承受的di/dt降低了86%。最后,通过低电压实验验证了配合方案与设计方法的可行性。

Active current injection direct current(DC)circuit breaker(CB)bears very high loads of di/dt during small current interruptions,which may easily lead to a failed interruption.This paper proposes a coupling method of a current injecting DC CB and a superconducting fault current limiter(SFCL).Voltage during the quenching process is utilized to charge the capacitor flexibly.With the aid of unique quenching characteristics under different fault conditions,reverse currents provided by the circuit breaker follow the fault current peak value automatically.The di/dt pressure on vacuum interrupters is significantly reduced,promoting the reliability of small current interruptions.A mathematical model of the proposed topology is established in a 200 kV circuit.The rated current interruptions and 30%and 60%of rated fault current interruptions are analyzed.The di/dt under 30%of rated fault current interruptions decreases to 86%compared with the classical current injection DC CB.Finally,the feasibility of the coupling method is verified by low voltage experiments.