Operating method of BESS for providing AGC frequency control service considering its availability maximization

Battery energy storage system (BESS) attract the attention of the power system operators with its fast response to a disturbance in spite of its limited energy capacity. This paper proposes the operating method of BESS for following the Automatic Generation Control (AGC) frequency control which is centrally distributed by a system operator. As BESS needs to just meet the control requirement from the system operator, it should be able to properly manage the state of charge (SOC) of BESS to be available to control signal. For doing these, the proposed method distributes the control requirement to available batteries in proportion to its SOC. In addition, unavailable batteries are controlled to recover the SOC to an appropriate range, and the recovering power is supplied by available batteries meeting the control requirement. Moreover, the proposed method manages the efficiency of power conversion system (PCS) by limiting the number of PCS to be assigned for the low control requirement. Finally, the case studies are carried out to verify the effectiveness of proposed strategy.