An Improved Hierarchical Control Structure For Robust Microgrid Operation and Seamless Mode Transfer Under Linear and Nonlinear Loads Conditions

This paper proposes the improved hierarchical-based control of microgrid based on proportional and multi-resonance controllers to compensate for harmonic distortion of nonlinear loads. moreover, the probable transition of mg, especially from grid-connected to unplanned islanding and unintentional mg resources outage were studied. in current and voltage controllers of three-phase vsis which are located in the inner level, the proportional and multi-resonant controllers are implemented. to attain proper decoupled (p-q) power-sharing, a selective harmonic type virtual impedance, and a droop-based control are implemented at the primary level. next, to reach better restoration and subsequently, seamless transition in accidental islanding, unintentional mg-dg’s outage, and synchronization process, the advanced three-phase srf-pll with in-loop maf along with a simple adaptive lookup table are implemented in the secondary level of the control. the matlab/simulink simulation results verified that the proposed method improved the performance of control, effectiveness, and robustness in upstream or local grid variation.