The Testing And Analysis Of Power Quality In Traction Substation

With rapid development of electrified railway in China, Power quality problems caused by electric traction have attracted more and more attention. Electric traction, which is the electric locomotive running on the electrified railway, is a kind of load that is single-phase, high-power and nonlinear. Compared with other load in power system, while the locomotive is moving on the rail and feeding current, it brings in larger negative current and higher harmonic to the power net as a result of its characteristics, high power, wide distribution, strongly impulse and so on, thus the power quality is affected badly.An-ding and Nan-xiang traction substations of Beijing-Shanghai electrified railway line is pilot projections of power quality improvement by Ministry of Railway. The scheme of fixed compensation (FC) + TCR is adopted in An-ding substation and FC+SVG in Nan-xiang. They are aiming at the reactive power compensation, filtering is also considered. The improvement scheme in Nan-xiang can also solve the negative sequence problem. It is first time of be used in China. It will be active guiding significance to test and analyze the schemes to the further improvement of power quality in electrified railway in China.In order to get the firsthand data, we did the field test to the substations in July in 2008 and April in 2009. To meet the requirement of the subject, power quality analysis system is developed by Delphi language for data acquisition and analysis which are used to get the relative statistical results of power quality indices. The data of power quality's quantization technical index in traction power supply system is obtained through the comparative analysis of different operation mode. The paper emphatically analyzed the power quality indices which are strict examined by state grid corporation, such as harmonic content, voltage distortion rate, triphase unbalance degree and power factor and so on. The power qualities of grid and traction power supply system are evaluated and the regulation effects of SVC and SVG for power quality are verified. Based on the actual situation of electric railway in china present, reasonable proposals are given for regulation effects' disadvantages of the two kind compensation devices, which can provide regulation reference for power quality in our country's electric railway in the future.