Frquency Regulation of Microgrid with Battery Droop Control

One of the potential problems with increasing renewable generation in microgrid is frequency regulation. Due to high variability of renewable generation resources, the imbalance between load and generation may lead to instability of the system. Since the microgrid can not compensate the power imbalance from the main grid, demand response in general and battery storage system specifically, can contribute in frequency regulation of microgrid. Conventional generator regulates the frequency with load frequency control (LFC) loop. Batteries connected to inverters can also contribute in regulating the frequency with the embedded frequency-watt control curve in inverter. In this paper, distributed battery storage systems are utilized to correct a given frequency deviation in the microgrid. The battery contribution is analyzed in centralized and decentralized environments. The optimal value of droop of distributed batteries are obtained and the small signal stability of the system is investigated.