Probability Model Of Traction Power Supply Load Considering Correlation And Its Impact On Power System

In recent years,China has vigorously developed High-speed railways as an important part of transportation construction,which greatly meets the needs of social production,living,and also meets China's environmental requirements for energy conservation,emission reduction,clean and environmental protection.However,in peac with the use of a large number of highly volatile,non-linear and single-phase loads,it has brought many adverse effects on the normal operation of China's power system.Therefore,it is particularly necessary to carry out research on the accurate modeling of traction power supply load and its impact on the power system,traction power supply load is referred to as traction load.This article is based on the premise that the measured traction load distribution is known,and makes a probability model of traction load considering correlation and its impact on power system,and use it in railway compensation devices,the specific research content and innovations are as follows:(1)For the general irregularly distributed traction load,the traditional parameter method cannot accurately reflect its load distribution characteristics,which will cause a large error in traction load modeling.Based on the measured data,this paper proposes to use the non-parameter kernel density estimation method to build the cumulative distribution Function,this method does not need to assume that the form of the probability density function is known.It only starts from the data sample itself to study the persistence of its traction load distribution,which can truly reflect the asymmetry,multi-peak and other details in the actual distribution,which makes the probability function more applicable and helps to improve the accuracy of traction load modeling.(2)When analyzing the distribution of traction load,it is found that there is an uncertain correlation between the loads of the two power supply arms.Therefore,this paper introduces Copula theory to analyze and study the related traction load.Based on the measured data,the Copula function parameters are calculated and the best Copula function is selected according to the correlation index,by connecting the traction load considering the correlation to the power system,the influence of the traction load correlation on the operation of the power system is analyzed.Taking the measured load as a reference,the degree of deviation and the degree of fluctuation is used to evaluate the accuracy of the built correlation model,the simulated load with and without correlation and the measured load are connected to the IEEE-30 nodesystem in turn,to verify the accuracy of the influence of the built correlation model on the power system power flow distribution;When studying the influence of its related characteristics on the power quality of the power grid,a simulation model of the traction system considering the correlation of the traction load is established,and analyze it from the perspective of harmonics and negative sequence.The simulation results show that the simulation result of traction load considering correlation factors is closer to the result of measured load than the loads without correlation,which verifies the validity and accuracy of the established correlation model.(3)Finally,in order to reflect the practical application value of the built correlation model in the study of traction load of High-speed railways,this paper takes the current research focus of railway compensation devices on Railway Power Conditioner(RPC)as an example,to analyze the research value of power quality control measures considering the correlation factors of traction load.This paper proposes to improve the traditional uncorrelated correlation traction load in RPC simulation into a load considering correlation factors.The simulation results found that the negative sequence current and harmonic current of the load considering correlation are relatively lower than those the load without considering correlation,indicating that the power quality compensation effect of the simulation has been more improved,and it reflects the practical application value of considering the traction load correlation factors.