Harmonics Analysis for High-speed Electric Traction System

The harmonics characteristic of electric traction system is directly affected by variation of locomotive power, and the harmonics characteristic of high-speed electric multiple units (EMU) is different from that of AC/DC locomotive. On the basis of analyzing harmonic voltage generation process and the equivalent circuit of electric traction system, this paper presents a study for modeling harmonic current injected by a typical EMU - CRH2. Voltage and current under traction and regeneration braking are simulated. Then the frequency spectrum characteristics and dynamic characteristics of harmonic voltage and current versus locomotive power level are analyzed. Simulation results indicate that properties of harmonic voltage vary little; but the ones of harmonic current vary obviously, especially the harmonic components decrease as the power level increases. The tested results agree well with simulation results, which indicate the correctness and feasibility of the harmonic model and the theoretical analysis.