Multi-functional control strategy for power quality improvement of three-phase grid using solar PV fed unified power quality conditioner

This article presents a generalised integrator with a band-pass filter frequency locked loop (GI-BPF-FLL) control algorithm for the solar photovoltaic (SPV)-integrated unified power quality conditioner (SPVUPQC) system. This control algorithm extracts fundamental components (FC) of the distorted and deformed input signals, and it has the competence of eliminating DC-offset. The key objective is to decrease the number of sensors used in the control algorithm of the SPVUPQC system while enabling the power quality enhancement features in the distribution grid. The effectiveness of the presented GI-BPF-FLL control algorithm and its performance comparison with the conventional control algorithm are discussed in both the time domain as well as frequency domain analysis. The SPVUPQC system consisting of a distribution static compensator (DSTATCOM) and a dynamic voltage restorer (DVR), to compensate simultaneously both the voltage distortions, sag/swell etc. as well as current harmonics, reactive power and load currents unbalances etc. The model of the SPVUPQC system is developed in the MATLAB/Simulink environment, and its results are presented to demonstrate its capabilities. The system's validation is also done on the hardware prototype, and it performs effectively for the voltage and current power quality enhancement simultaneously. The load side voltages magnitudes, grid side voltages and the grid currents total harmonic distortions are found within the boundaries specified in the IEEE standard 1159 and the IEEE standard 519.