Design of a High Performance Resonant Controller for Improved Stability and Robustness of Islanded Three-Phase Microgrids

Islanded microgrids face difficulties due to the presence of nonlinearity, asynchronous load, and unknown load dynamics. Moreover, conventional control schemes in the islanded microgrids show slow dynamic response, significant voltage-current oscillations, frequency change, low output power quality, and less reference tracking capability. In this regard, a robust and high performance controller is required against the instability issues related to various load conditions and sudden load changes in the solar photovoltaic (PV)-based solar photovoltaic (PV) based islanded microgrids. This paper presents the design and implementation of a second-order high performance resonant controller for robustness and improving the stability of a solar PV based three-phase islanded microgrid (TPMG) under varying system conditions. The design of the proposed controller is based on a backstepping scheme where control Lyapunov functions are used to find transfer functions. The transfer functions that are obtained by this approach are the transfer functions of a resonant controller with proportional-integral controllers. The performance of the proposed controller is investigated in MATLAB/Simulink. The simulation results demonstrate the robustness of the proposed controller in terms of stability, dynamic responses, voltage-current oscillations, total harmonic distortion, and reference tracking of the TPMG. Moreover, the performance of the proposed controller is illustrated against various load dynamics and sudden load changes. A laboratory-scale experiment verifies the simulation results of the proposed controller.