Analysis of Multiconverter - UPQC Configuration with Different Filtering Schemes for Shunt Compensation

Abstract

Power quality (PQ) issues, such as voltage and current distortions, sag, swell and interruptions in supply voltage, pose a big challenge for the distribution systems. The increasing grid penetration of intermittent renewable energy sources has further complicated this issue. Unified power quality conditioners (UPQCs) can act as a comprehensive solution for these PQ issues by providing harmonic current mitigation, reactive power compensation and sag/swell alleviation. However, UPQC fails to maintain load voltage in case of interruption in supply voltage. Multiconverter-UPQC (MC-UPQC) topology addresses this drawback and maintains continuous power supply even during the grid failure by interline power feeding from adjacent live feeder. Synchronous reference theory is widely employed for the control of MC-UPQC. In such a scenario, the dynamic response of the MC-UPQC is significantly affected by the low pass filtering of the d-axis component of load current. This paper analyzes the dynamic response of MC-UPQC with different filtering methods. This analysis reveals that 2^nd order Butterworth filter provides the best dynamic response for the shunt controller among the tested filter topologies. This is supported through the simulation and experimental studies presented in this work.