Influence Analysis of Droop Coefficients on Load Margins for AC/DC Hybrid Microgrids

When operating in islanded mode, an AC/DC hybrid microgrid usually adopts droop control methods. The droop control coefficients of interconnected converters and distributed inverters have a great influence on load stability margin of the system. Droop control coefficients are used to be determined by capacity ratio of the inverters, frequency and voltage regulation range, however, the influence of droop coefficients of multiple inverters on overall voltage stability of the system is not fully considered. For this issue, a new method for calculating load stability margin of the hybrid microgrid considering droop control parameters is proposed. Through further traversal of the droop parameter space, the optimal range of droop control parameters which maximize the load margin of the microgrid is obtained from the overall perspective. The system is more stable in the optimal parameter space. The results are verified based on a 12-node AC/DC hybrid microgrid.