Analysis of Power Quality Issues of Electrified Railway System

Railway electrification has advantages such as high speed, heavy load, high energy utilization and good economic benefits. But the traction load of electrified railway is a high power, single phase and nonlinear load, its access to the grid will bring about power quality problems such as harmonics, three-phase imbalance which go against safe and economic operation of power system. Firstly after electrified railway connects to power system the characteristics of power quality are introduced in this paper. The main problems, harmonic and negative sequence caused by the traction load of electrified railway, are analyzed in detail. Then, the influence of harmonic and negative sequence on power system is summarized. Finally, the current measures to improve the power quality of the utility grid are classified. A reference is provided for the power quality evaluation and treatment after the electrified railway connects to power system.