Research on harmonic current distribution of beijing´s rail traffic power supply system

This paper will discuss the monitoring and data analysis of nonlinear load power quality by analyzing electrical railway, which is a typical nonlinear load in Beijing. Firstly, this paper will introduce a method of designing the software and hardware of a kind of highly accurate and large-capacity energy quality data recorder, which is capable of accurately recording voltage, electric current wave, etc., data on site for a long standing and can restore the original data with upper computer in lab. Secondly, this paper will analyze the data collected by the energy quality data recorder from Beijing Xiazhuang transformer substation, which is responsible for supplying electricity to Daqin railway and is a typical nonlinear electrical railway load. On the one hand this paper presents the complete data of fundamental current and harmonic current in a typical working day (as shown in graphs) and analyzes the correlation between fundamental current and main harmonic current. On the other hand, this paper also analyzes the amplitude of main harmonic current distribution with statistical methods and establishes an autoregressive (AR) model to illustrate the distribution of main harmonic current. From the above analysis we can get the key data for evaluating the impact generated by this transformer substation on the grid´s electrical energy quality.