Harmonics And Negative Sequence Assessment In Tpss Considering The Influence Of Background Harmonics And Background Negative Sequence

The rapid development of China's high-speed railway has brought great challenges for both traction power supply system(TPSS)and power system.The harmonics and negative sequence in TPSS of high-speed railway are the typical power quality problems,which has been concerned by both TPSS and power system.Therefore,based on the harmonics and negative sequence problem in TPSS of high-speed railway,this paper will conduct research from the aspect of measurement,modeling and assessment.The main work of this paper is as follows:Firstly,a power quality testing system has been developed.This equipment is developed based on the virtual instrument development platform named Lab VIEW and NI Compact-RIO Controller,and can realize the measurement and data storage of multiple electrical nodes,which has laid a good foundation for the following research.Secondly,this paper studied the distribution characteristics and model method of background harmonics and background negative sequence.Based on large amount of field measurement data,the distribution characteristics including time-varying,daily periodicity and probability distribution characteristics of both have been analyzed.And the probability distribution of amplitude shows a multiple-peaks,heavy-tails and skewed distribution.Then,a dayparting modeling method based on Skew Normal Mixture Model(SNMM)has been proposed.This modeling method could not only fit the multiple-peaks,heavy-tails and skewed characteristics effectively,but also can describe the time-varying characteristics well.Thirdly,an assessment method for harmonics and negative sequence in TPSS has been proposed in this paper.Considering the influence of background harmonics and background negative sequence to the assessment result,this paper established this assessment method based on the covariance characteristic of random rectors.This method referred the harmonic responsibility division method in power system.Then,field measurement data has proved the applicability of this harmonic and negative sequence responsibility division methods.Lastly,the influence rule of each factor for the responsibility division result has been analyzed.Based on the voltage and current simulation data at PCC(the point of common coupling),this paper analyzed the influence rule of each factor for negative sequence assessment result using control variable method.And these influence factors mainly include the regional grid,traction transformer,traction load,the characteristics of TPSS and so on.Considering the influence of background harmonics and background negative sequence,this paper fully verified the reasonableness of this assessment method based on both field measurement data and simulation data.And this assessment method may will provide an effective theoretical basis for the realization of rewards and punishment power supply scheme in the near future.