Mitigation of harmonics using fuzzy logic controlled shunt active power filter with different membership functions by instantaneous power theory

The main objective of this paper is to develop the Fuzzy controller with different membership functions (M.F's) to improve the power quality of shunt active filter by mitigating the harmonics. Issues related to harmonics are of a greater concern to engineers and building designers because they do more than just distort voltage waveforms, they can overheat the building wiring, cause nuisance tripping, overheat transformer units, and cause random end-user equipment failures. Thus power quality is becoming more and more serious with each passing day. As a result, active power filters have gained a lot of attention due to their excellent harmonic compensation. However, the performance of the active filters seems to have contradictions with different control techniques. To carry out this analysis, active and reactive power method (p-q) is considered. When the supply voltages are balanced and sinusoidal, all Fuzzy membership functions (Trapezoidal, Triangular and Gaussian) are converging to the same compensation characteristics. However, the supply voltages are distorted and/or un-balanced sinusoidal, the fuzzy logic controller result in different degrees of compensation in harmonics. Extensive simulations were carried out. The simulations were performed under balance, unbalanced and non sinusoidal conditions. The Fuzzy logic controller with Gaussian M.F gives dynamic performance than Fuzzy with other two M.F's.