Performance Analysis of Type-1 and Type-2 FLC based Shunt Active Filter Control Strategies for Power Quality Improvement

In recent years electrical power quality has been an important and growing problem because of the proliferation of nonlinear loads such as power electronic converters in typical power distribution systems. Particularly, voltage harmonics and power distribution equipment problems result from current harmonics produced by nonlinear loads. The electronic equipments like; computers, battery chargers, electronic ballasts, variable frequency drives, and switch mode power supplies, generate perilous harmonics and cause enormous economic loss every year. Problems caused by power quality have great adverse economic impact on the utilities and customers. Due to that both power suppliers and power consumers are concerned about the power quality problems and compensation techniques. Issue of harmonics are of a greater concern to engineers and building designers because harmonics can do more than distort voltage waveforms, they can overheat the building wiring, causes nuisance tripping, overheat transformer units, and cause random end-user equipment failures. Thus power quality (PQ) has become more and more serious with each passing day. As a result active power filter (APF) gains much more attention due to excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (threephase without neutral), and four-wire (three-phase with neutral) ac power networks with nonlinear loads. The APF technology has been under research and development for providing compensation for harmonics, reactive power, and/or neutral current in ac networks. Current harmonics are one of the most common power quality problems and are usually resolved by the use of shunt active filters. In this research work, the performance of the shunt active filter control strategies has been evaluated in terms of harmonic mitigation and DC link voltage regulation. Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. This research presents different topologies and controllers with enhanced performance of shunt active filter for power quality improvement by mitigating the harmonics and maintaining dc link voltage constant. For extracting the three-phase reference currents for shunt active power filters, we have developed shunt active filter Instantaneous active and reactive power “p-q” and Instantaneous active and reactive current “Id-Iq” control strategies. For regulating and maintaining the DC link capacitor voltage constant, the active power flowing into the active filter needs to be controlled. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed PI Controller, Type-1 and Type-2 Fuzzy logic controller with different Fuzzy MFs (Trapezoidal, Triangular and Gaussian). The proposed APF is verified through MATLAB/SIMULINK. The detailed real-time results using Real-time digital simulator are presented to support the feasibility of proposed control strategy