Research Of Damping Scheme Of Electrified Railway For Passing Neutral Section

Single-phase,50Hz AC power system is applied in Chinese electrified railway, in the meanwhile the characteristics of traction load is a random load including a large amount of harmonics. In order to reduce the impact of negative sequence produced by traction power system, traction system is alternatively feeding by the three phase power system. The neutral section is built for the purpose of avoiding the short-circuit between the different phases. However, in recent years, the practically operational experience reflected the fact that there are severe transient phenomena existing in the traditional passing neutral schemes adopted by Chinese electrified railway. As a result, the train and the catenary network are usually damaged during the process of passing neutral section. The process of passing neutral section has been a big threat to the operation safety of railway system. With the rising requirement for the operation safety of Chinese railway, it is necessary to develop the novel scheme for passing neutral section according to the practical circumstance of China.In this thesis, the grounding scheme and on-board scheme, which are widely utilized in Chinese railway system, have been studied firstly, including the process of passing neutral section and the mechanism of the over-voltage and over-current phenomena. Based on the investigation of the traditional scheme of passing neutral section, the damping scheme has been proposed. The criterion and the method of selecting the damping parameter have been discussed in this phase. Afterwards, the applications of damping scheme in both the phase splittings of traction substation and section post have been researched, and the process of damping scheme has been analyzed as well as the arcing during the process. Moreover, two novel damping schemes have been briefly researched and compared with the current damping scheme. Finally, based on the platform of Matlab/Simulink, the simulating model for the process of passing neutral section has been developed. The on-board scheme and the damping scheme have been researched by using the simulating model, as well as the two novel ones.The results show that the damping scheme could effectively resolve the backwards of traditional schemes and suppress the transient process of passing neutral section for ensuring the operational stability and safety. The current scheme has a simple structure and is suitable for appling at section post. The Y-type novel one can solve arcing problem because of the three-open type articulated phase insulator, and the parallel novel ones can solve the power consumption problems. These two schemes is fit for utilizing at the traction substation. The damping scheme has a a high reliability and is able to adapt the development needs of Chinese railway system. This scheme is applicable to the engineering proliferation.