Hybrid UPQC topology endowed with an Isolated Bi-Directional DC-DC Converter

Abstract-This paper introduces an original hybrid unified power quality conditioner (HUPQC) topology as an alternative solution to electrical power quality problems. The proposed HUPQC consists of the shunt hybrid active power filter (SHAPF), the dynamic voltage restorer (DVR) and the isolated bi-directional DC-DC converter (BiDC) located at the common DC link. The SHAPF enables reduction in the voltage rating of the DC link capacitor, helps to reduce the cost and the size of the DC link and hence reduces switching losses of the voltage source inverter (VSI). Besides the novelty of its topology, dynamic reactive power compensation capability is realized for the first time in literature within HUPQC concept by achieving adaptively controlling DC link voltage. The BiDC not only provides isolation and bi-directional power flow between the DVR and the SHAPF but also operates to keep the DC link voltage of DVR constant against adaptively changing DC link voltage of the SHAPF. In addition to these, a new hybrid voltage sag/swell detection algorithm based on the combination of the improved clarke transformation and the enhanced phase-locked loop is developed and introduced. In order to verify the viability and effectiveness of the proposed HUPQC topology, experimental studies are carried out.