Protection of microgrids with a high penetration of inverter-coupled energy sources

Microgrids with a high penetration of inverter-connected DER provide a high level of flexibility and control over the exchanged active and reactive power as well as local voltage magnitude. This paper discusses the protection of these micro-grids, focussing on islanded operation. First a current limitation method for the inverters is discussed, which is necessary to avoid inverter disconnection during faults. Then a method to determine the type of fault is described. Finally a new protection strategy is presented, operating without the need for communication.