Power quality advancement of grid-tied photovoltaic system: using optimal phase locked loop based control strategy

This manuscript proposes an optimal phase locked loop (PLL) based control method for voltage source inverter (VSI) of grid-tied solar photovoltaic (PV) system. The proposed work in this manuscript is an extended version of the paper presented in IEEE ICEPE-2020 conference, in which a sliding discrete Fourier transform (SDFT) and moving average filter (MAF) are resorted for the extraction of fundamental grid frequency and phase angle. Through extensive simulations and hardware experiments, it is demonstrated that the proposed method achieves a phase angle tracking accuracy of ± 0.05 deg and a grid frequency tracking error of less than 0.01 Hz under varying grid conditions. The adaptive and preferable tracking of phase angle as well as grid frequency ensures the generation of reference grid currents properly, which enhances the novelty of proposed work. Additionally, the JAYA optimization is used to extract the proportional and integral (PI) gain of PLL’s phase detector, resulting in approximately 90% reduction in settling time and 60% improvement in steady-state error compared to conventional methods. To minimize the overshoot and undershoot from DC-link voltage during loading condition, the current gain of an outer DC-link voltage control loop was added with modified quadrature axis current gain, resulting in a 30% reduction in transient voltage deviations. Further, numerous operational VSI with proper control retains the power management capability to set the seal on consumers requirement and mitigates the power quality (PQ) issues. Finally, with the help of MATLAB/Simulink studies and dSPACE-1104-based real time hardware setup, the accomplishment of proposed work is well validated.