Fault Location Analysis On All Parallel AT Traction Network Based On SVD

As high-speed railways are developing towards high speed and high operation density, the traction network is required to supply more stable and secure electricity. All parallel auto transformer(AT) power supply mode facilitates the development of high-speed railways because of its stable voltage level, favorable electromagnetic compatibility and low construction cost. Highly precise and reliable traction network fault location is an fundamental guarantee for the normal operation of high speed railway.Firstly, the dissertation analyzes the fault characteristics and extraction methods of traveling wave for the high-speed railway traction power supply system briefly, and proposes the basic framework of fault location. Secondly, on the basis of multi-conductor transmission line theory and classical Carson theory, all-parallel AT power line impedance model is established, on which the overall model of the traction power supply system is built. Then, the dissertation suggests a method of using the similarity between the fault currents with power frequency to find out the fault setions on detection region, and the validity of this method has been verified consequently. It is considered that the effective extraction for faint travelling wave head and reliable identification for the second reflected wave are some important factors which can greatly affect the reliability of fault location, a binary recursive singular value decomposition(SVD) method is introduced into the extraction of some singular points. By comparing the simulation results with ones from the wavelet transform, the binary recursive SVD method can get more accurate results in the singular point extraction. Finally, a new fault location algorithm free from wave interference and line length change is proposed through the improved D-type location algorithm, and therefore the complete fault location in the traction network is conducted with the combination of the improved D-type fault ranging algorithm and the binary recursive SVD method.Based on the above theoretical analysis, the singular points are extracted by binary recurive SVD to fault current waveform obtained from the simulation, and the coordinates of these singular points in the waveform can be turn into the time point when the wave reaches inspection point, and then the time point is substituted into the improved D-type formula to get fault location. The fault location research results shows that the mixed fault ranging method with the combination of binary recursive SVD and the improved D-type algorithm is effective and applicable in fault location of all parallel AT traction power supply system.