Coordinated primary and secondary control with frequency-bus-signaling for distributed generation and storage in islanded microgrids

In this paper, a distributed coordinated control scheme based on frequency-bus-signaling (FBS) method for a low-voltage AC three phase microgrid is proposed. The control scheme is composed by two levels. Firstly a primary local control which is different for the DGs and the ESS is proposed. The ESS adopts FBS control which is based on changing slightly the bus frequency in the microgrid when the state-of-charge is near to the limit. This way, the DG controller when detecting that the frequency is increasing, will reduce the injected power by using a virtual inertia control loop. Then secondary control is implemented to restore the frequency deviation produced by the primary ESS controller while preserving the coordinated control performance. Real-time simulation results show the feasibility of the proposed approach by showing the operation of the microgrid in different scenarios.