Robust Control for Rooftop Solar PV-BES Microgrid and its Seamless Grid Synchronization

This research work targets on synchronization of single-stage solar photovoltaic (SPV)-battery energy storage (BES) based microgrid with the power grid. This system provides seamless synchronization between on-grid and off-grid modes of operation, power quality (PQ) improvements, frequency variation mitigation, operation under polluted grid conditions, and unbalanced load compensation. This system uses a dual-third order generalized integrator-reduced order generalized integrator-frequency locked loop (dual-TOGI-ROGI-FLL) to realize seamless switching between on-grid and off-grid modes of operation with a solid-state transfer switch (SSTS). A TOGI-quadrature signal generator (TOGI-QSG) based current controlled algorithm provides gating pulses to the VSC during the on-grid mode. A voltage-controlled algorithm is used during the off-grid mode of operation. A comparison of filtering ability between DTOGI-ROGI-FLL and SOGI-FLL during distorted grid conditions is made. Satisfactory results of MATLAB simulations in both dynamic and steady-state conditions validate the system's performance.