Microgrid Protection Based on Positive Sequence Fault Component Current

When the microgrid is faulty, the bidirectional power flow, multi-source characteristics and various control modes lead to the complexity of the microgrid fault characteristics. The traditional relay protection is difficult to adapt to the existing microgrid structure. Therefore, according to the characteristics that positive sequence fault current is not influenced by the system power supply potential, the positive sequence fault current phase of bus flow into each feeder is used to distinguish the bus fault, feeder fault and fault location, the method is not affected by the operation mode of the system and can be accurately located under various fault conditions, and put forward a new Protection start criteria. The new starting criterion solves the contradiction between the sensitivity of fault operation in traditional differential protection areas and the reliability of out-of-zone operation. Finally, a simulation example is carried out by using Matlab / Simulink software. The result proves the reliability and correctness of the protection method.