Reduce the Participation of Synchronous Dispersed Generator in Fault Current

High Distributed Generation (DG) penetration increases distribution system short circuit currents level, which can disrupt protective relays coordination. Synchronous-machine DGs (SMDG) are main agent in disrupting the coordination of the OverCurrent relays (OCR). This paper proposed a field discharge circuit to reduce the generator’s current during faults. The proposed method limits the participation of synchronous dispersed generator in fault current by controlling the generator field current. After fault detection, exciter will be separated from the field winding and field discharge circuit become series with the field circuit. This paper investigated two kinds of field discharge circuit (resistance discharge circuit and complex discharge circuit); that each one apply in the network depend on DG’s output power and existence relay in the network. The proposed method implemented on a case network in Matlab/SIMULINK; which the simulated results confirmed the effectiveness of this method.