Subjective–objective methodology on selection of power quality compensation technology in AC–DC network with electrified railways

Abstract

Electrified railways contain DC devices and cause power quality (PQ) issues such as harmonics, unbalance, and low-power factor, which should be solved by the most effective compensation technology to reduce the cost. In addition, it is common that more than one issue is caused at a supply bus, with either some issue affecting more than the others or all issues equally affecting, depending on different buses. Different PQ compensation technologies are used in the past work for the improvement of PQ at the network bus side. However, few of them have provided theoretical justification on which technologies should be selected for different network buses with different issues. This study investigates a subjective–objective methodology to provide suggestions on which compensation technologies should be selected for network buses, why and how. The importance of different PQ issues will be obtained and shown as overall weighting factors. The overall weighting factors are derived from the subjective weighting factor, obtained from existing industry standards, and the objective weighting factor, obtained from the entropy of information. The methodology will be applied to a real 124-bus AC–DC network with electrified railways. Based on the overall weighting factor obtained, the most effective compensation technology can be determined.