3-Phase 4-wire UPQC Topology with reduced DC-link Voltage rating for Power Quality Improvement using Fuzzy Controller

Unified power quality conditioner is one of the advanced forms of power conditioning device, which is a combination of back to back connected series APF and shunt active power filter (SAPF) connected to a common DC link voltage. This topology will facilitates this device to have a reduced dc-link voltage without reducing its compensation capability. This device is mainly used in improving the power quality. For the improvement of power quality (PQ) complications in a 3-phase 4-wire distribution system, two topologies are presented. In this paper a four-leg voltage source inverter (VSI) based topology of a four-wire UPQC is discussed in this work. The performance of each topology of this device is evaluated for different PQ problems such as voltage harmonic mitigation, load balancing, source neutral current mitigation, current harmonic mitigation, and power-factor correction. The main purpose this device is to compensate load current and supply voltage imperfections. Converter and control analysis is presented together with the results showing the modes of operation. Detailed design aspect of the series capacitor and VSI parameters has been discussed in this paper. For better power quality improvement the PI controller is replaced by the fuzzy controller and the results are verified. The proposed topology enables UPQC to compensate current harmonics, voltage sags, and voltage swells with a reduced DC-link voltage without reducing its compensation capability by resolving the circuit in MATLAB/SIMULINK software.