An Integrated Multi-Function Control Scheme for Independent BESS in Islanded Synchronous Generator-Based Microgrids

In this article, a multifunction control scheme is proposed for battery energy storage system (BESS) as an independent grid-supporting distributed energy resource in islanded/stand-alone microgrids (MGs) including synchronous generator. The proposed controller increases the utilization factor of the BESS to participate in electricity market ancillary services using its available unused capacity. The proposed controller incorporates adaptive frequency control, voltage regulation, as well as unbalanced load compensation. Additionally, an adaptive high-pass filter is proposed which enables the BESS to compensate for frequency deviations according to its state-of-charge for a longer effective life span of batteries. Furthermore, a voltage control loop is integrated to regulate the BESS point of common coupling voltage during low-voltage conditions by injecting reactive current. Finally, the available capacity of the BESS grid-connected converter is utilized to compensate for the unbalanced currents drawn by the loads. Simulation and experimental tests are compared under several scenarios to validate the proposed controller performance. The results reveal the efficacy of the proposed controller in maximizing the BESS utilization factor in islanded/stand-alone MGs.