Projection-Iterative-Method-Based Coordinated Power Control for Renewable-Rich Islanded Microgrids

Abstract

High renewable-energy penetration introduces rapid source-load variations and operating uncertainties into islanded microgrids, challenging conventional droop control in terms of dynamic frequency/voltage regulation and proportional power sharing. This paper proposes a coordinated control strategy integrating adaptive droop control, dynamic virtual impedance, and a Projection-Iterative-Method-Based Optimizer (PIMO). A constrained multi-objective formulation coordinates active- and reactive-power-sharing errors, frequency and voltage deviations, virtual-impedance regularization, and parameter variation, while stability is enforced through Lyapunov- and eigenvalue-based feasibility criteria. PIMO periodically coordinates the droop coefficients and virtual-impedance parameters within prescribed feasible bounds. The proposed strategy is evaluated in MATLAB/Simulink under five-stage load transitions and renewable-rich scenarios covering PV penetration levels from 30% to 90%, irradiance and temperature variations, simultaneous source-load disturbances, and operating constraints. Compared with adaptive droop control, the proposed strategy reduces the full-window frequency and voltage RMSE by 9.4% and 26.6%, respectively. The active- and reactive-power-sharing errors decrease to 1.73% and 2.08%, while the worst-case settling time is reduced to 220 ms. In addition, PIMO achieves a mean execution time of 28.4 s within the adopted 60 s supervisory update interval. These results demonstrate improved dynamic regulation, proportional power sharing, and feasible supervisory optimization under renewable-rich operating conditions.