A Fault Detection Method of Microgrids With Grid-Connected Inverter Interfaced Distributed Generators Based on the PQ Control Strategy

The fault characteristics of an inverter interfaced distributed generator (IIDG) depend on its control strategy and whether it has a low voltage ride-through (LVRT) capability, which cannot be a simple equivalent to a constant power or current source. Thus, it is necessary to consider the specific control strategy of IIDGs and perform specific research on the fault detection method of a microgrid. Based on the fault models of a grid-connected PQ controlled DG with an LVRT capacity, this paper analyzed the fault component characteristics of a microgrid under different operating conditions, such as high-impedance faults and low-impedance faults. The fault point is located using a new fault detection method based on the phase differences between the positive-sequence fault component of the bus voltage and the positive-sequence fault components of the currents in the feeders. Finally, PSCAD/EMTDC is used in the simulation analysis, and the simulation results verified the validity of the fault detection method.