基于故障电流控制的直流微网过电流保护研究

目的  随着分布式电源以及电动汽车等新型负荷的发展，直流微网相较于交流微网有着换流环节少，系统损耗低等优点，成为目前的研究热点。直流微网覆盖范围小，且接入了大量的分布式电源，因此发生极间短路故障时，故障电流上升速度快，幅值大，使得传统交流配电网采用的过流保护难以实现级差配合，给故障定位造成了极大的困难。 方法  对此，针对直流微网故障电流的特点，提出限流与保护相融合，基于故障电流精确控制值设计过流保护整定值的方法，结合各支路合理的容量设计，可轻松实现级差配合，准确定位故障。 结果  文章在PSCAD/EMTDC仿真平台上搭建相应的直流微网模型，对所提保护方案进行了仿真验证，结果表明该方案能正确定位故障点并迅速切除故障。 结论  所提的保护方案保证了过电流的选择性。这验证了所提保护方案的合理性。

Research on Protection Scheme of DC Microgrid Integrated with Fault Current Limiting Control Technology

Introduction With the development of new loads, such as distributed power sources and electric vehicles, DC(Direct Current) microgrids have the advantages of fewer commutation links and lower system losses than AC(Alternating Current) microgrids, and have become the current research hotspot. Due to the small coverage of the DC microgrid and access to a large amount of distributed power sources, the fault current rises quickly with a large amplitude when inter-pole short-circuit fault occurs, making it difficult to achieve differential coordination with traditional overcurrent protection used in AC distribution networks and posing a great challenge to fault localization. Method Therefore, in response to the characteristics of fault current in DC microgrids, the method for designing overcurrent protection setting value based on the precise control value of fault current through the integration of current limiting and protection was proposed. Combined with the reasonable capacity design of each branch, it can easily achieve differential coordination and accurately locate faults. Result A corresponding DC microgrid model is built on the PSCAD/EMTDC simulation platform. The proposed protection scheme is simulated and verified, and the result shows that the scheme can correctly locate the fault point and quickly remove the fault. Conclusion The proposed protection scheme can ensure the selectivity of overcurrent, which verifies the rationality of the scheme.