Harmonics Current Sharing Strategy for Parallel Interfaced Multiple Solar PVs and BES Under Various Operating Conditions

Oversizing voltage source converter (VSC) too much is a common consequence of conventional control methods used to maintain sinusoidal utility currents in a central battery energy storage (BES) and multiple solar photovoltaic (PV) arrays-based microgrids interfaced in parallel at the point of common coupling (PCC). It is done to meet harmonics demand of local loads, resulting in increased installation costs and reduced reliability of whole system. An intelligent harmonics current sharing (HCS) strategy is proposed in this work for distribution of reactive and harmonic demands of local loads based on operating modes. Multiple cascaded second-order generalized integrator-based frequency locked loop (CSOGI-FLL) is implemented to estimate dominant harmonic components of nonlinear load currents. Moreover, utility frequency estimated using CSOGI-FLL is utilized to regulate PCC parameters during synchronization of microgrid with utility while supporting HCS. System is simulated at various operating conditions in MATLAB/Simulink environment, and results are validated on a real-time OP5700-based test bench.