Impact of inverter interfaced distributed generation on overcurrent protection in distribution systems

The fault behavior of an inverter interfaced distributed generator (IIDG) is determined by its control, which is significantly different from a conventional generator. This paper examines in detail the key features of IIDG´s fault behavior with respect to interference with distribution protection. As an example, the fault behavior of a commercially available photovoltaic converter is shown through a hardware-in-the-loop (HIL) simulation using real-time digital simulator (RTDS). A case study is then performed using the HIL setup to investigate the impact of IIDG on the recloser-fuse coordination in the fuse saving mode. The results illustrate that due to fault current limiting behavior of inverters, IIDG marginally impact primary and back-up protection in a distribution system. But with high penetration level, IIDGs may disturb the recloser-fuse coordination.