Study On Electric Energy Metering Of High Speed Traction Power Supply System

With the development of the electric power market,the reasonable measurement of electric energy is the common concern of the power grid and railway departments.As a high-voltage and large-capacity user,electrified railway generates harmonic,negative sequence and other power quality disturbance,which makes the power measurement problem more complicated.In order to measure electric energy effectively,it is necessary to analyze the different factors of quality power disturbances including negative sequence,harmonic and reactive power in the power grid and the traction power supply system.Therefore,it is necessary to find the source of power quality disturbances,determine the direction of disturbance,define the responsibility,and calculate the electric energy correctly.Power quality disturbance is considered as studying object in this paper,brought by electrified railway traction load.The paper is aimed to improve electric metering method.This paper focuses on the research of the power definition,the negative-sequence power flow,and the influence of harmonic on electric power metering method.Specific contents are shown as follows:First of all,the research on electric energy metering at home and abroad present situation and the characteristics of the traction power supply system are analyzed and summarized,and introduces the principle and structure of the traction power supply system,quality characteristics and the load characteristics of the electrified railway power system.Secondly,the definition of the current power factor,the definition of the arithmetic power factor,the definition of the vector power factor and the equivalent power factor are introduced from the perspective of the power factor to adjust the electricity charge.The rationality of power definition with negative-sequence and harmonic is compared and analyzed.Then the application characteristics of different apparent power definition methods are analyzed by simulation and measured data.The results show that the equivalent apparent power factor can reflect the influence of negative-sequence and harmonic of the traction power supply system on the power grid,and has wider applicability and rationality.Thirdly,the negative-sequence power flow of traction load is analyzed.It also deals with problems of electric metering methods with negative-sequence,and to this point,it puts forward positive-sequence active power electricity metering scheme.The rationality of different electricity metering scheme is compared by positive and negative sequence flow analysis.And then,on the basis of the calculation method of the positive-sequence power in the three-phase unbalanced system,the theoretical expressions of the measurement error under different electricity metering methods are obtained quantitatively.Through simulation verification and measured data on the proposed model and algorithm,the results indicate that the proposed positive-sequence active power electricity metering scheme can alleviate the problem of unreasonable measurement of electric energy with negative-sequence.This way,reasonability and effectiveness in the error quantitative calculations are verified accordingly.Finally,aiming to electric energy metering in harmonic condition,analyze the problems of active power electric metering method in harmonic condition,and compare with the rationality of fundamental active power metering,the weighted coefficient of energy metering and active power energy metering.On basis of calculation method of fundamental power in three-phase non-sinusoidal system,theoretical expressions of measurement error in fundamental active power and active power electricity metering methods are obtained quantitatively.Simulation results based on the proposed model and algorithm and measured data indicate that fundamental active power electricity metering scheme can alleviate the problem of unreasonable measurement of electric energy in harmonic condition,the weighted coefficient of active power energy metering can carry on the quantitative analysis to harmonic;thus reasonability and effectiveness in error quantitative calculations are verified accordingly.