Analysis of Harmonics Infiltration Produced by Electrification Railroad on 220kv and 35kv Network

Through analysis of measure data on three 220 kV transformer substation in Shanxi China, the results show that harmonic current produced by electrification railroad injects into power system in a proportion through 110 kV point of common coupling, and the infiltration coefficient is closed to 1 if harmonic current direction is 110 kV to 35 kV, this phenomenon coincides with usual law; but there has strong infiltration in harmonic voltage between 110 kV and 220 kV system, and the infiltration coefficient could be not negligible, it does not coincide with usual law. Therefore, 110 kV harmonic distortion produced by electrification railroad not only infiltrates to 220 kV system thought coupling transformer, but also disseminates even hundreds of kilometres thought electric fence.