Analysis of static VAr compensators installed in different positions in electric railways

With the power quality problems of electric railways becoming more and more serious, static VAr compensators (SVCs) have been widely used for power quality management. SVCs can be installed in the low-voltage side of traction substations, the high-voltage side of traction substations or the electric railway power supply side of substations. Different installation positions result in different compensation effects. In this study, characteristics of harmonic and negative sequence currents in the low-voltage and high-voltage sides of traction substations are analysed theoretically. Four schemes with SVCs in different installation positions are proposed. Then based on the measured datum and waveforms, simulation of each scheme is implemented, respectively, using PSCAD/EMTDC software. By comparing the compensation effects of the four schemes, the best SVC installation scheme in the low-voltage side of the traction substation is recommended for the measured traction substation. With SVC, the electric railway will have a less negative effect on the power grid. This study can also be applied to other SVC applications with non-linear loads, such as arc furnaces, rolling mills or electrochemical devices.