A generalized droop-control scheme for decentralized control of inverter-interfaced microgrids

In this paper, a generalized droop-control scheme for low-voltage microgrid is proposed. The control scheme includes three mutually interacting droop control loops for regulating the power flows between the primary energy sources and the common ac bus. The first droop control is adopted directly from the conventional P/f and Q/V droop control for enabling an automatic power sharing between parallel-connected inverters in the microgrid. The second droop control monitors the dc bus voltage´s condition and uses it to modify the settings for the first droop control, and hence, adjust the power sharing capacity of the inverter based on the power generating capacity of the primary energy sources. The third droop control resembles the first droop control, but acts on the dc-dc-converter interfaced primary energy sources for enabling an automatic power sharing between them. The proposed control scheme is useful for realizing a fully decentralized control of a microgrid with improved reliability since no critical communication is needed between the main components of the system. The design methodology of the control scheme is presented, and its effectiveness is verified by both simulation results.