Efficient Harmonic Current Mitigation in Unbalanced, Nonlinear Loads Using Grid-Connected Three Phase Four Wire Active Power Filter

Currently, there is a significant level of energy consumption stemming from nonlinear loads. These loads serve as the origin of current harmonics, which consequently infiltrate the power grid, leading to waveform alterations in the source and a decline in its overall quality. The primary aim of this study is to mitigate the impact of harmonics by restoring the current to a sinusoidal form. To achieve this objective, an electrical system will be modeled using the Simulink software. Within this system, an active power filter comprising three levels and four parallel wires will be implemented. The control methodology for the filter's development is based on the multiple synchronous frame technique. A harmonic current extraction method that employs a multiple synchronous frame technique to generate precise reference currents with reduced computational overhead and a control strategy for the APF have been developed to enhance performance under nonlinear, balanced, and unbalanced load situations. The proposed method significantly enhances harmonic current extraction performance and reduce Total Harmonic Distortion (THD) to acceptable levels and minimize excessive neutral currents. The superiority and accuracy of the proposed algorithms are proved by mathematical analysis and Matlab Simulink simulations.