A Study On Traction Substation Connection And The Influence Of Harmonic Penetration To Power System Of Electric Railways

The electrified railway is the trend of railway transport development for its prominent advantages. In our country, most electric locomotives are of rectification loads, thus a great lot of harmonic currents (mainly including the 3rd,5th,7th order)prcduced by train is directly injected into the power system and cause voltage distortion. In the meanwhile, harmonic currents will bring a lot of effects to other users. Because people have stricter request to power quality, it is important to study the power quality problem in power system caused by electrified railways. Furthermore, people can get schemes and measures to harness harmonic currents through study it. So the study will have a great significance to Power system department and railway department.In traction substation, the traction transformer and the parallel capacitive compensator have particularities compared with generally power system substation, because they need to satisfy traction power supply. When establish the model of traction substation, phase coordinates method need to be adopted because of the unbalance property of electrified railway loads. Traction substation node admittance matrix is established through analysis electric performance of 5 kinds traction transformer, compensation devices and power source. This is a preparation for emulation.Traction loads' harmonic currents is random and fluctuate, so it is difficult to describe harmonic currents only use typical data or waveforms, use several data to emulation can't get a real conclusion, must depend on field measuring data to emulation and statistics. So, from May to August in 2007, representative traction substations are measured when they are running, get great of field materials and this will provide reliable data for emulation.An emulation program is developed use C++ program language. When input electric parameters, program can establish node admittance matrix of traction substation, when input realistic measure data, program can calculate harmonic voltages caused by traction loads' harmonic currents. A bulky capacity loads data and a light capacity loads data are calculated by this program and get power system voltage distortion at different traction transformer, different power system short circuit capacity and different compensation devices capacity. And some conclusions are get through statistics and analysis the calculate result.