Frequency Control of Battery Energy Storage System as Primary Reserve

초록

Recently technology of battery energy storage system (BESS) is actively developed, and research related to application of this to power system is widely conducted. Frequency control service is an area for using BESS in the power system. Since BESS has faster response than conventional generator, effective frequency control is possible. In this paper, system structure and operation algorithm is proposed to utilize BESS as primary reserve of frequency control service. The top agent is named by power management system (PMS). This agent manages entire system and transmits parameters to sub-agent. Sub-agent is named energy storage system controller (ESSC) that conducts creation of output reference responding to measured frequency. The output reference is calculated by droop characteristic that is used in governor free control of conventional generator. When state of charge (SOC) of BESS is out of operation range, exit strategy decreases the output linearly to prevent the additional disturbance caused by rapid reduction of output. In order to maintain SOC at an appropriate level recovery strategy is proposed. Recovery strategy restores SOC of ESS to a constant output in stable frequency. Through PSCAD simulation in conjunction with the C language, proposed structure and algorithm is verified.