Resilient Control Strategy for a Grid Interactive PV-UAPC System Under Non Sinusoidal Grid and Load Disturbances

The widespread deployment of power electronics based nonlinear loads, coupled with the increasing prevalence of highly distorted grid voltages, presents critical power quality challenges in grid interactive distributed networks. To tackle these challenges, this study employs a band pass filter based third order generalized integrator (BTOGI) structure to effectively synchronize the grid with a photovoltaic fed universal active power converter (PV-UAPC) system. The proposed filtering technique alleviates both grid side and load side abnormalities, suppresses dc offset, compensates for unbalance, and minimizes steady state error while improving dynamic response and enhancing harmonic elimination. To verify the efficacy of the proposed approach, the grid interactive PV-UAPC system is simulated under diverse operating conditions in MATLAB/Simulink. Furthermore, to ensure practical feasibility and resilience under non ideal grid and load conditions, the simulation findings are validated using a real time OP5700 based test bench. A comparative performance analysis between the second order and third order generalized integrators highlights the superior performance of the proposed BTOGI filter, particularly under distorted grid voltage and unbalanced load conditions. Furthermore, across all operating modes, the proposed control approach ensures that the total harmonic distortion (THD) of utility grid currents and load voltages maintains significantly below thresholds set by the IEEE 519 guideline, thereby enhancing overall power quality and system reliability.