Control strategy for frequency regulation in islanded distribution systems with synchronous distributed generators

The occurrence of islanding of distribution systems is an operational event ever more present in power systems due to the insertion and expansion of distributed generation. In this context, this paper proposes a local load shedding relay to enable the islanded operation of distribution systems with distributed synchronous generators. A supplementary control loop added to a battery energy storage system is also proposed in order to contribute to the frequency regulation in the islanded system. The supplementary control provides frequency regulation support during the transition from grid-connected operation to islanded operation, as well as during normal operation of the islanded system.