Self-Synchronizing Robust Control Scheme for Harmonic Current Supression of Grid-Interfaced PV System Under Distorted Grid Voltages

This paper presents a self-synchronizing robust control scheme for a single stage three-phase grid-interfaced photovoltaic (GIPV) system that does not requires a phase locked loop (PLL). Under the harmonically distorted grid voltages caused by nonlinear load the proposed control scheme utilizes an enhanced proportional multi-resonant (EPMR) current controller to effectively address the issue of grid current harmonics. The computational burden on the digital controller of the GCPV system reduces due to the elimination of a dedicated synchronization unit (PLL) in the proposed robust control scheme. The efficacy of the proposed robust control scheme is verified by experimentation in various grid scenarios, including situations with distorted grid voltages and changes in grid frequency. Further, an modified incremental conductance (MINC) maximum power point tracking (MPPT) algorithm is utilized to ensures the reduction of power oscillations to a minimum, particularly when faced with swiftly changing atmospheric conditions. To validate the effectiveness of the proposed robust control scheme, real-time digital simulations are conducted using the OPAL-RT real time simulator.