Research On The Stray Current And Rail Potential Of VSC-Based MVDC Railway Electrification System

The VSC-Based MVDC Railway Electrification System(RES)are being considered as an alternative solution for the high-speed railway in the future as it’s simple in design,costeffective,does less harm to the quality of power supply and its distributive network.In this paper,two important aspects of the MVDC RES,that are the selection of voltage level for the catenary system and the consideration of stray current and rail potential during implementation,are studied.Firstly,the selection of voltage level for MVDC RES is discussed considering various quantities which would affect its voltage level.Meanwhile,various factors related to how each would influence in the system were identified and defined.By using a simple algorithm,a voltage level is derived and its performance was verified.Secondly,a deep study of the stray current is performed,starting with how and where it is generated,and its interference is described.Stray current is not a problem in the railway system until it starts corrosion of any metallic structure embedded in the vicinity of the railway track.Hence,the process of corrosion caused by the stray current is briefly introduced.Similarly,a study has been performed about the distribution of stray current along the railway track.The theoretical aspect of rail potential is also explained with the introduction of the rail potential control device.To verify the theoretical analysis,the distribution of the stray current along the railway track,use of rail potential control device and its effect on the stray current were observed through simulation model built in MATLAB/Simulink.Additionally,various stray current control schemes and the use of stray current collection mat were discussed.Finally,the main research work and shortcoming in this thesis were summarized and the follow-up research work have prospected.