An Advanced Proportional Multiresonant Controller for Enhanced Harmonic Compensation With Power Ripple Mitigation of Grid-Integrated PV Systems Under Distorted Grid Voltage Conditions

This article proposes an advanced integrated control strategy for enhanced grid current harmonic compensation with power ripple mitigation in a grid-integrated photovoltaic systems (GIPVS) under distorted grid voltage conditions. The proposed control strategy consists of an advanced proportional multiresonant (APMR) current controller and a compensator for grid voltage sag (CGVS), which is implemented with a phase-locked loop block. The APMR is designed in the α-β reference frame and minimizes the harmonics of the grid injected current. The CGVS, along with the APMR, eliminates the active and reactive power ripples under unbalanced voltage sags conditions. Further, an adaptive step size incremental conductance (ASINC) maximum power point tracking controller in integration with the proposed control strategy is implemented. Along with current harmonic reduction by APMR, the ASINC method ensures effective and faster tracking of maximum power point and negligible oscillations in the steady-state under different environmental conditions. By utilizing the proposed APMR control strategy, the frequency adaptability of the GIPVS is improved compared to the conventional proportional multiresonant (PMR) control strategy under grid frequency deviations. It successfully keeps the grid current total harmonics distortion below the acceptable limits for the grid voltage polluted by several odd harmonics, up to the nineteenth harmonics. The proposed control strategy of APMR with CGVS almost completely eliminates the power ripples in even severe unbalanced voltage sag conditions. Experimental studies are carried out using a real-time digital simulator to verify the effectiveness of the proposed control strategy in comparison with the conventional PMR controller.