Faulty section location scheme for distribution grid with inverter interfaced distributed generation

As more and more Inverter Interfaced Distributed Generation (IIDG) units have been integrated into the distribution network, the power output and fault characteristics of IIDG pose great challenges to conventional protection principle and faulty section location method. Therefore, this paper proposes a novel scheme to locate the faulty section in the distribution network with IIDG. Firstly, for the internal and external asymmetric faults, the direction difference of negative sequence current between both ends of every feeder segment is analyzed, and a negative sequence current direction comparison based fault location scheme is proposed. Secondly, for a symmetric fault, according to the amplitude differences of fault current contributed by system source and IIDG, a positive sequence current amplitude criterion is constructed to locate the faulty section. The proposed scheme is realized by smart terminal unit (STU) which has intelligent judgement ability and can exchange the information with adjacent STUs in real time. Simulation results verify the effectiveness of the faulty section scheme.