Mitigation of Harmonic Distortion in Grid-connected PV System Using Passive Filter

Abstract

The increasing integration of grid-connected solar photovoltaic (PV) systems into modern power networks has introduced various power quality issues, especially harmonic distortion caused by inverter switching operations. Excessive harmonic distortion can negatively affect electrical equipment, increase power losses, reduce system efficiency, and violate harmonic standards. This paper investigates harmonic distortion in a grid-connected solar PV system based on the Thapyaywa Solar Power Plant and its associated transmission network. The study system is modelled in MATLAB/Simulink using collected plant and grid data. Harmonic analysis is performed at the Point of Common Coupling (PCC) using Fast Fourier Transform (FFT) analysis. The simulation results show that significant harmonic distortion exists in both voltage and current waveforms before filtering. The dominant harmonic components are mainly the 5th, 7th, and 11th harmonics. To mitigate these harmonics, single-tuned passive filters are designed and implemented for the 5th, 7th and 11th harmonic frequencies. After applying the designed passive filters, the voltage THD and current THD at the PCC are significantly reduced. The results demonstrate that the designed filters effectively improve power quality and reduce harmonic distortion in the grid-connected PV system. Therefore, the proposed passive filtering approach can effectively improve harmonic performance, system stability, and reliability in grid-connected solar PV systems.