Power Quality Improvement in Three Phase Four Wire Distribution System with Implementation of Fuzzy Logic Controller Based Adaptive Shunt Active Filter

摘要

Non-linear loads and applications of power electronics in 3P4W (three phase four wire) distribution system are the major sources of harmonics. The power quality compensator which mitigates the problem related to Current harmonics is Shunt active filter (SAPF) or passive filter. Active filtering is the most efficient mitigating method adopted for reactive power compensation and mitigation of harmonics. The power quality compensator proposed in this paper is a SAPF which reduces the %THD, compensates reactive power and mitigates neutral current under unbalanced non-linear load condition. A 3-φ MOSFET based 3 leg VSI (Voltage Source Inverter) with DC bus capacitor as energy buffer is employed to realize the SAPF. Fuzzy logic based Direct control method is the propounded control strategy implemented for the estimation of reference current and to keep the voltage of DC capacitor to its reference value. Switching signals for the VSI is generated using Hysteresis current controller. T-connected and Zig-Zag transformers are implemented to reduce the neutral current to about 1/10th of its original value in unbalanced Non-linear load conditions. The propounded control strategy performance is validated and analyzed using MATLAB software.