Secondary frequency control strategy for BESS considering their degree of participation

With the increasing penetration of the renewables, power system requires more resources with high ramping rate in the secondary frequency control (SFC). Battery energy storage system (BESS) is regarded as an effective one to follow the regulation signals. Meanwhile, the optimal operation of BESS cluster brings challenges to independent system operator (ISO), as more BESSs are involved in a control area. Specifically, the control center tries to take full advantages of the characteristics of BESS meeting frequency regulation requirement, and to follow the state of charge (SoC) limitation in BESS distribution. Therefore, a degree of participation (DP) based SFC for BESS cluster is proposed in this paper. In detail, a fuzzy-logic inference system (FLIS) is applied to determine a proper DP by considering the system frequency regulation requirements and BESS SoC. Also, the coefficients of the BESS operation cost function vary with DP, and the distribution of BESS in SFC is achieved to minimize the operation cost of BESS cluster by quadratic programming algorithm (QPA). At last, the promising results shows the BESS is well arranged by the proposed DP-based SFC, balancing the system frequency regulation requirement and BESS SoC limitation.