Study on measurement methods of harmonic of traction load

Traction load is one of the main harmonic sources in utility. The harmonic of traction load is very complex because of its random variety characteristic. The exact measurement of traction load harmonic is the precondition of finding out harmonic characteristic and harmonic compensation. IEC61000-4-7 is an international standard about how to measure harmonic and inter-harmonic of utility. Based on analysis of recorded harmonic data of traction load using measurement methods defined in IEC61000-4-7, comparison of many measurement methods of harmonics are done in this paper. The best suitable method for measuring harmonic of traction load in IEC61000-4-7 is also put forward in this paper. This study has great significance on measuring precision of traction load harmonic.