含多类型故障限流设备动作的直流电网保护时序配合

柔性直流电网作为新能源并网的有效手段,要求能够可靠开断直流故障电流。直流电网中配置的多种类型故障限流设备间的故障保护时序配合亟须研究。文中基于直流电网直流线路双极短路故障,研究了故障限流器、直流断路器、半桥全桥混合型模块化多电平换流器以及DC/DC变换器这几类多类型故障限流设备的故障保护时序配合。针对包含环网状以及辐射状结构的复合型多端直流电网系统中的不同区域,配置不同类型的故障限流设备,同时采用检测故障电流变化率的方法判断直流断路器是否可靠动作。根据不同的故障区域,提出了相应的故障限流设备间的保护时序配合方案,并且考虑了部分限流设备如直流断路器拒动后其他限流设备的动作逻辑。在PSCAD/EMTDC仿真中验证了提出的直流电网中多类型限流设备保护时序的可靠性和有效性。

Time-sequence Coordination of Protection in DC Grid with Multi-type Fault Current Limiting Devices

As an effective means for renewable energy integration, the flexible DC grids requires reliable breaking of DC fault current. The time-sequence coordination of fault protection among various fault current limiting devices in the DC grid needs to be studied. In this paper, based on the pole-to-pole short circuit faults in DC grid, the time-sequence of fault protection of multi-type fault current limiting devices such as fault current limiters, DC circuit breakers(DCCB), DC/DC converters and hybrid modular multi-level converters composed of half-bridge and full-bridge sub-modules are studied. Current limiting devices are configured for different areas of the compound multi-terminal DC grid system including the meshed network and radial structure. In the meanwhile, the detection method of the change rate of fault currents is used to determine whether the DCCB is operating reliably. According to different fault areas, the time-sequence coordination plan between fault current limiting devices is proposed, and some current limiting devices are considered such as the action logic of other devices when DCCBs refuse to operate. The PSCAD/EMTDC simulation results verify the reliability and validity of the time-sequence logics of multi-type current limiting devices protection in the DC grid.