±10 kV直流配网用混合式中压直流断路器拓扑设计与试验

Topology Design and Test of Hybrid Circuit Breaker Used in±10 kV MVDC Distribution System

为解决±10 kV柔性直流配电网发生短路时故障电流大,开断短路电流困难的问题,提出一款±10kV混合式中压直流断路器拓扑方案。利用PSCAD/EMTDC软件对该直流断路器拓扑进行仿真。仿真结果表明:当系统发生短路时,直流断路器能够在2.54 ms(<3 ms)时间内分断2.5 kA短路电流,转移支路中承压绝缘栅双极性晶体管(insulated gate bipolar transistor,IGBT)两端最大电压约为17.5 kV,同时研究了RC回路中不同R值(1Ω,5Ω,10Ω)对系统电压振荡波形的影响,R取值越大振荡时间越小;同时理论推导了直流断路器分断过程中的电气应力暂态方程。最后基于所提出的拓扑结构研制了±10 kV直流断路器样机,搭建试验平台对直流断路器开展分断试验。试验结果表明:该款±10 kV直流断路器能够在3 ms内双向(正向和反向)开断100 A小电流和2.5 kA短路大电流,试验结果与仿真结果保持一致。

In order to solve the problem of high fault current and hard current breaking when the short circuit of±10 kV voltage source converter-high voltage direct current(VSC-HVDC)distribution system happens,we developed a hybrid medium voltage direct current(MVDC)±10 kV circuit breaker.The PSCAD/EMTDC was used to simulate the DC circuit breaker topology.The simulation results indicate that,when the short circuit of power system happens,DC circuit breaker can break the 2.5 kA short current within 2.54 ms(<3 ms),and the insulated gate bipolar transistors(IGBTs)of transferring branch can withstand voltage stress 17.5 kV.Meanwhile,the effect of R value(1Ω,5Ω,10Ω)on the system voltage oscillating waveform was investigated,and the results show that the larger R value leads to a smaller oscillation time.Furthermore,we theoretically derived the electrical stress temporary equation in the breaking process of DC circuit breaker.Finally,based on the proposed topology,the±10 kV DC circuit breaker prototype was developed,the test platform was built to perform a breaking test for the DC circuit breaker.The test results show that the±10 k V DC circuit breaker can break the small current 100 A and short current 2.5 kA in both directions(forward and reverse)within 3 ms.And the test results keep the same with the simulated results.