Discharge rate balancing control strategy based on dynamic consensus algorithm for energy storage units in AC microgrids

A dynamic consensus algorithm-based coordinated secondary control with an autonomous current-sharing control strategy is proposed in this paper for balancing discharge rate of energy storage systems (ESSs) in an islanded AC microgrid. The dynamic consensus algorithm is applied for information sharing between distributed generation (DG) units in order to regulate the output power of DGs according to ESS capacities and state-of-charge (SoC). The proposed controller can not only effectively prevent operation failure caused by over current and unintentional outage of DGs by means of balanced discharge rate control, but also provide fast response and accurate current sharing performance due to an autonomous current-sharing controller at primary level. In addition, expandability, flexibility and high reliability can be obtained thanks to the distributed architecture. Based on the developed linearized state-space model in z-domain, both the system stability and parameter sensitivity were analyzed. A comparison between experimental results obtained from using the conventional power sharing control and those obtained from the proposed coordinated control using a setup with three 2.2 kW DG units are presented to verify the effectiveness of the proposed controller.