Adaptive Network Protection in Microgrids

Microgrids comprise low voltage distribution systems with distributed energy resources (DER) and controllable loads which can operate connected to the medium voltage grid or islanded in a controlled coordinated way. This concept aims to move from “connect and forget” philosophy towards an integration of DER. Microgrids are expected to provide environmental and economic benefits for endcustomers, utilities and society. However, their implementation poses great technical challenges, such as a protection of microgrid. Local generation in a combination with a possible islanded operation can pose protection sensitivity and selectivity problems in case of fault depending on the relay settings. This paper presents a novel adaptive microgrid protection system using digital relaying and advanced communication. The protection system is based on a centralized architecture where relay protection settings are modified centrally with regard to a microgrid operating condition.