A comparative study of fuzzy logic based UPQC and D-STATCOM for mitigation of power quality problem

Abstract

This paper begins by investigating a power quality problem in the case study area using monthly energy consumption data, the peak and minimum load of the substation, a fault summary, and the RMS voltage profile of the case study area. The content of the paper comprises three parts: the first involves MATLAB design and simulation of D-STATCOM with a fuzzy logic controller for the selected case study area. The second part entails MATLAB design and simulation of the DVR with a fuzzy logic controller. The final part presents a hybrid of the DVR and the D-STATCOM back-to-back using a DC link capacitor to implement a more recent and effective power quality improvement technique, namely UPQC. In the case of a three-phase fault, the voltage sag in the case study area is 0.6PU, with the remaining 0.4PU drop-down voltage requiring injection using the proposed FACT device for compensation. All proposed power quality problem mitigation techniques inject the required voltage and compensate for the voltage sag in the substation. For instance, D-STATCOM compensates the RMS voltage from 9KV to 14KV, DVR compensates the RMS voltage from 9KV to 14.7 KV, and UPQC compensates the value to 14.9KV. Due to the three-phase fault, the rise in reactive power of the existing outgoing feeder is 13MW. This unexpected rise in reactive power is reduced to 2.6 MW using D-STATCOM, DVR reduces it to 1.2 MW, and UPQC reduces the value below 1MW. The existing power factor of the case study area without any mitigation technique is 0.68. All proposed techniques improve the existing power factor to a more acceptable value. For instance, D-STATCOM improves the power factor from 0.68 to 0.83, DVR improves the value to 0.88, and UPQC, the more accurate power quality mitigation technique, improves the power factor to 0.93. Finally, the results are compared based on the simulation results.