Comparison of UPQC Topologies for Power Quality Enhancement in Grid Integrated Renewable Energy Sources

Abstract

Unified power quality conditioner (UPQC) is a custom power device that provides a complete power quality solution. The only drawback of UPQC is that it cannot maintain the voltage in case of grid interruption. Different UPQC topologies are reported. This paper presents a detailed comparison of design and operational aspects of two UPQC topologies, namely (i) UPQC- Multiconverter, and (ii) UPQC-Distributed Generation. Both of these topologies address the inability of UPQC to maintain continuous power supply even under grid failure, while meeting the IEEE standard 519. An attempt is made to compare the performance of both these topologies with respect to harmonic current and reactive power compensation, sag/swell mitigation, number of switches, switch ratings, etc. Further, in case of UPQC-Distributed Generation a sub classification based on energy sources and energy storage elements is also presented. The operation of the two topologies under different operating scenarios is also compared.