Approximated fuzzy logic controlled shunt active power filter for improved power quality

Shunt active power filters have been widely used for power quality improvement. With the advancement in artificial intelligence techniques, the applications of fuzzy logic-based control systems have increased manifolds. This paper proposes a reduced rule fuzzy logic controller (FLC) in the voltage control loop of a shunt active power filter (APF), which is approximating a conventional large rule FLC. The difference between the controlled outputs of two controllers is compensated by proposed compensating factors. The dynamic response and harmonic compensation performance of proposed 4-rule approximated fuzzy logic controller (AFLC) is compared with 25-rule FLC. A three-phase shunt APF is used for harmonic and reactive power compensation. The proposed scheme is tested with randomly varying single and multiple non-linear loads. The simulation results presented under transient and steady-state conditions confirm that the proposed 4-rule AFLC efficiently approximates the 25-rule FLC. The proposed control methodology takes less computational time and computational memory as the numbers of rules are reduced significantly.