Power Quality Analysis And Voltage Sag Indices Using UPQC Under Various Fault Conditions

Abstract

The expanding manipulation of non linear loads in the electrical power distribution system is intensifying the distortions in the current and voltage waveforms. Besides, the distribution system in the network of power system is unbalanced due to unsymmetrical faults. Also, with the insertion of Distributed Generation (DG's) into the power system, the level of fault current is increasing, which causes some power quality(PQ) issues in the distribution system. Voltage sag, swell and harmonics are the major power quality issues and the UPQC is considered as an effective device to compensate them. This paper describes about the voltage sag, current, real and reactive power in the distribution system during fault, prefault and post fault conditions. Three different fault conditions namely single line to ground fault(LG), double line to ground fault(LLG), and Three phase to ground fault(LLLG) are considered and various system indices such as sag score, Voltage sag energy index, Voltage Sag Lost Energy index, Voltage Sag Severity, Phase Voltage Unbalance Rate and power factor are analyzed. Also the performance analysis of THD is carried out in the distribution system. The potency of UPQC scheme is illustrated using MATLAB/SIMULINK environment.