SOC management of BESS for frequency regulation with hysteresis loop control

For stably operation of BESS for frequency regulation, BESS needs a SOC management algorithm. This paper proposes that BESS changes a base point for the SOC management for stable operation to keep high performance score. To manage SOC of BESS providing frequency regulation, the base point is changed in accordance with a proposed hysteresis loop control when the SOC exceeds a limit, BESS provides the additional output as much as changed base point more than a regulation set point. Through this process, BESS recovers SOC and keeps stable operation range and high performance score. Three cases are observed: 1) without hysteresis loop control; 2) using hysteresis loop control; 3) using hysteresis loop control at high SOC. Cases simulated by using PSCAD/EMTDC. For the accuracy of simulation, this paper performs simulation based on real frequency regulation signal data of the PJM in USA. First case simulation shows that the SOC exceeds stable range and this situation finally causes shutdown the BESS because SOC reaches full. Second case simulation shows that SOC is managed in stable operating range. And final case shows that BESS is recovered from high SOC. This means BESS operators should set proper operation range and SOC limit for the SOC management. A simulation results show that if the proposed algorithm is applied to BESS for frequency regulation, the BESS is able to keep high performance score. Also proposed algorithm can be applied to BESS to perform other roles in power system.