Providing Frequency Response in Isolated Microgrids Using Battery Energy Storage Systems

Microgrids in an isolated mode have low inertia. Therefore, when a disturbance occurs, the system is subjected to a large frequency deviation and may lead to a blackout. Battery energy storage systems (BESSs) are installed in microgrids to handle this situation, as the response of BESSs is faster than that of synchronous generators. The purpose of this article is to investigate and compare the difference between the outcome of using the BESS with the virtual droop and the virtual inertia to provide frequency regulation. The results show that the BESS with both control approaches can reduce the frequency deviation in the microgrid. The small virtual droop constant can decrease more frequency deviation. On the other hand, the large virtual inertia constant can decrease more frequency deviation. Furthermore, the characteristics of the power discharged from the BESS with two control methods are different. The BESS controlled by the virtual droop only discharges power, while the BESS controlled by the virtual inertia discharges power first, and then recharges power until the frequency goes back to the nominal value.