Resilience Analysis of Islanded Microgrids with Droop Control through Reachable Set Computation

The dynamic resilience of islanded microgrids is primarily determined by the droop coefficients of inverter controllers for distributed energy resources (DERs). To efficiently quantify the impact of droop coefficients, a reachability analysis approach is presented in this paper, through which the time/frequency domain analysis becomes unnecessary. Zonotope technique is used to model the changes of droop coefficients and then integrated into the computation of reachable sets. Numerical examples on an islanded microgrid system have verified that the reachable set can bound all dynamic trajectories of the system under disturbances and exhibited the droop coefficients can highly influence the islanded system in presence of typical constant-impedance, constant-current, and constant-power (ZIP) power loads. The simulation results also offer an insight into enhancing the system's dynamic resilience through optimizing the droop coefficients.