Research On Evaluation And Mitigation Of The Power Quality Affceted By Electrified Railways On The Power Grid

As the rapid developing of electrified railway in China,it has more and more impact on power quality of the power grid.Therefore it is of vital importance to make a reasonable assessment of the impact grade and correspondingly take effective measures of governance.The main contents of this paper include: modeling and simulation of typical electrified railway power supply system and research on harmonics and negative sequence influence characteristics of electrified railway,evaluation of influence on the power grid quality caused by electrified railway and administration research of harmonic and negative sequence influence on power grid.V/V,YNd11,Scott,impedance matching balance PSCAD simulation model of traction transformer,and the PSCAD simulation model of the typical AC-DC electric locomotive,AC-DC-AC electric locomotive were established in this paper.By researching these models,the characteristics of electrified railway's influence on the power quality was obtained.On basis of analyzing electrified railway's influence on the power quality,the paper conducted a study on the evaluation of the electrified railway's influence.By simulation evaluation,data analysis and short-term prediction evaluation based on the measured data,more coherent evaluation process of electrified railway's impact on power grids was formed.In this process regional power grid whose electrified railway load distribution is concentrated was taken as research object.The harmonic effect with different operating conditions of the power grid and the negative sequence were evaluated.Data analysis evaluation is based on the real measured grid data,then the harmonic multi-limit evaluation method were put forward.Electric characteristics,harmonic limits,load fluctuation and nonlinear of electric railway were taking into account.Different to existing harmonic assessment which were based on the measured data and simulation evaluation.This paper presents a short term prediction method to access electrified railway's influence based on BP neural network.The method realized short-term prediction for harmonic wave evaluation of non-holiday load.The experiments proved its effectiveness.Based on evaluating the influence of harmonic and negative sequence caused by electrified railway,administration method of harmonic and negative sequence influence were studied in the paper.Power grid planning management and allocation optimization of passive power filter were two key points of research.The improvement effect of harmonic and negative sequence of power grid were conducted by line transformation and capacity enlarging of main transformer.PSO algorithm was researched and used to optimize passive power filter configurations,and experiment results proved its effectiveness to improve power quality after optimization.In addition,based on the above research,the paper has developed the software platform which is used for the evaluation and management of electrified railway on the power quality of the power grid,and the related function is realized.