Modeling and simulation of three phase inverter for fault study of microgrids

Single phase and three phase voltage source inverters are increasingly used to integrate electric power generation from solar photovoltaics with the electric distribution systems. The fault characteristics of an inverter interfaced generator is different from the fault characteristics of conventional synchronous generators because inverters are designed to restrict their fault currents to a low value. Such restriction in fault current thus poses a challenge to conventional protection schemes. In order to explore fault studies of distribution systems with inverter-interfaced generation, and to design appropriate protection schemes for such systems, a suitable inverter model is required. The purpose of this paper is to model and simulate a three phase inverter that is able to perform well in the presence of balanced or unbalanced loads, and is also able to restrict the fault currents effectively without significant distortions of voltage and current waveforms.