Adaptive Grounding Distance Protection for Inverter-Interfaced Distributed Generation

Due to the weak fault current feedability and phase-controlled characteristics of the Inverter Interfaced Distributed Generator (IIDG), the distance protection of the system with IIDG injected may not operate correctly when the single-phase ground fault occurs through the fault resistance. In this paper, considering the characteristics of voltage controlled positive sequence current source of IIDG, the sequence network analysis and calculation of single-phase grounding fault in the system with IIDG injected are carried out. The output current of IIDG after the fault is calculated by the positive sequence voltage approximation value of the connection point, and the measured impedance expression determined by the fault location, fault resistance and electrical volume before the fault is obtained. Thus, operating impedance boundary of grounding distance protection can be adjusted adaptively. The protection scheme is adjusted adaptively using only the electrical parameters before the fault, the protection can adapt change of the output current of the IIDG after the fault and improve the immunity to fault resistance for the grounding distance protection of the system with IIDG injected. Simulation based on PSCAD/EMTDC vermes effectiveness of the proposed protection.