Balancing and filtering of currents from an unbalanced voltage source using an active filter with the Zero Direct Power command method

Abstract

Balancing the unbalanced currents from the source is important to avoid the risks of overvoltage and damage to the various electrical devices. Non-linear loads absorb currents rich in harmonics, which affect the source current and make it distorted. The risks become more serious when those of the imbalance and those of the harmonics are added. The subject of this conference is the study of a dual-function energy system, which improves the quality of electrical energy by balancing the unbalanced currents from the source and compensating for the undesirable harmonics that distort the signal of the source current, using an active power filter whose command is “Zero Direct Power command (ZDPC)”. This method uses a conventional PI controller to regulate the voltage of the DC bus and a highly selective filter to separate the harmonics from the fundamental. By eliminating the undesirable harmonics, the source currents become almost sinusoidal with a harmonic distortion rate close to 1%, an imbalance rate below 1% and the reactive power decreases. This system is simulated using MATLAB/Simulink software. The results prove the robustness and feasibility of the ZDPC command which simultaneously guarantees the compensation of harmonic currents, the correction of the power factor and the balancing of source currents.