Reducing of Harmonic Distortion by Fuzzy System and Modified d-q Theory under Unbalanced Load

In this paper, a control method based on a fuzzy system with modified d-q theory is used to delete unwanted harmonic currents under an unbalanced load. The presence of these harmonics in the electric networks leads to many problems, such as overheating of rotating machines and distribution transformer, and perturbation of sensitive control equipment. Therefore, to address harmonic disturbances in power system networks, a Shunt Hybrid Filter (SHF) is proposed. In addition, in order to further improve the quality of electrical energy, making it compliant with international standards, we opted for fuzzy logic in the control method with a modified Phase Locked Loop (PLL). The principal objective is to improve the efficiency of HPF, suppress harmonic currents and consequently reduce Total Harmonic Distortion (THD) under 5%. The efficiency of a combined fuzzy logic and PI controller under an unbalanced load is evaluated by a simulation study using MATLAB/Simulink software, and the obtained results are presented