Harmonic Characteristic Analysis And Modeling For CRH380A High Speed EMU

With the fast development of high speed railways in China, the high speed EMUs (electric multiple unit) have been widely applied in the railway network as the main type trains of rail transportation. The EMU is featured with high power, high motion speed, high density and nonlinearity, and more and more attention has been paid for its adverse impact on the power quality issues of traction power supply system and connected power system. Therefore, this paper mainly focuses on harmonic characteristics and harmonic modeling of CRH380A high speed EMU based on large amount of field data. And the main work of this paper is as follows:Firstly, the harmonic mechanism of high speed EMU is analyzed in this paper. The traction drive system of high speed EMU, the working principle of pulse rectifier and the principle of PWM is systematically introduced in this paper. And the mechanism of high order and low order harmonics is theoretically analyzed, which laid a solid foundation for the harmonic characteristics and modeling analysis of EMU.Secondly, the harmonic characteristics of CRH380A high speed EMU are analyzed in this paper. The group methodology is applied for harmonic measurement and it can effectively relieve the spectral leakage caused by the fluctuation features of traction electrical quantities. And the magnitudes and angles of high/low order harmonics are analyzed and compared based on large amount of field data from CRH380A high-speed EMU. Furthermore, the dynamic features of harmonics are discussed in the perspective of stochastic fluctuations and compartmental statistics.Thirdly, the harmonic of CRH380A EMU is modeled with Norton equivalent circuit. This paper presented a harmonic modeling method for such EMU system based on field data and Norton equivalent model, which effectively reflected the influence of the harmonic voltage on harmonic current. Additional, the dynamic harmonic process of the EMU is also simulated with field data and the distribution range of calculated dynamic model and field data are compared.Lastly, the low order and high order harmonics are modeled with different methods, respectively. In allusion to low-order harmonics, with considering the different distributions under multiple working conditions, it was modeled with Monte Carlo method based on the classification of working conditions and power output. The statistics of harmonic current amplitudes was used for the probabilistic distribution and the Gauss parameters, and the modeling current results were obtained with Monte Carlo method. In allusion to high-order harmonics, with considering the interaction between harmonic voltage and harmonic current, the frequency-coupling-matrix based Norton harmonic model was built in the frequency domain of high-order characteristic harmonics, and the harmonic current was modeled with harmonic voltage.Above all, the harmonic characteristics of CRH380A high-speed EMU are analyzed based on field data, and the harmonic is modeled according to its features, which can provide supports for the harmonic evaluation of high-speed EMUs.