A NEW CONTROL ALGORITHM OF SHUNT ACTIVE POWER FILTER UNDER DISTORTED GRID VOLTAGE AND UNBALANCED SUPPLY CONDITIONS

To achieve maximum possible power factor and by keeping total harmonic distortion (THD) within the acceptable limit. A new control algorithm of shunt active power filter under distorted grid voltage and unbalanced supply conditions is proposed. A new control algorithm renders the optimal compromise between harmonic free (HF) and unity power factor (UPF) by keeping the total harmonic distortion (THD) of the source current within the standard range. In this paper, a new control approach for a three-phase four- wire shunt active power filter with PI and FUZZY controller under distorted grid voltage and unbalanced supply conditions is proposed. The algorithm employs a one-step process to get the conductance factors (only three). The extracted balanced set of voltages is multiplied with the constant conductance factors to get the required source currents. Using lagrangian technique mathematical formulas are derived for the conductance factors. Synchronous reference frame (SRF) theory is used to extract a balanced set of voltages from asymmetrical and distorted supply voltage conditions. Results acquired by simulations with Matlab/Simulink shows that the proposed control algorithm is very flexible and effective under steady and dynamic load conditions when compared to iterative OCA. Key Terms- Shunt Active power filter (SAPF), unity power factor (UPF), total harmonic distortion (THD), PI controller, fuzzy controller.