In recent years, the needs for train service have been steadily increasing in accordance with the expansion of the metropolitan area and the significant growth of passengers and freight. Further more the saturation of the road traffic accelerates the needs for the rail transportation. However, these social needs without any improvement for the existing railway facilities may cause operational problems, such as large voltage drop which might induce low voltage not to drive railway vehicles. In order to solve the problem on feeding system, the two measures can be taken into account; one is the reactive power compensation by installing SVC(Static VAr Compensator) or RPC(Railway static Power Conditioner), and the other is the active power supplying by installing STATCOM(Static Synchronous Compensator) or ESSs(Energy Storage System). However, these methods require a separate space and huge cost for the installation and maintenance. Therefore, it is important that to seek an effective and cost-efficient voltage regulation plan with minimizing the additional equipment in feeding system.
In this dissertation, in order to properly regulate the voltage of the train without installing additional equipment, a novel type of autotransformer and its operating strategies are proposed. The proposed tap-changing autotransformer is expected to raise the voltage between catenary and rail by regulating the turn-ratio between primary and secondary winding according to catenary voltage and verified its effects through the multi ports network analysis technique modeling of it. In addition, the turn ratio adjusting method based on the voltage across autotransformer is proposed. Through the simulation and analysis for the electric railway systems, it is shown that it can secure the load capacity and solve the large voltage drop problem by raising the voltage across railway vehicles back to the normal voltage level.
Additionally, since the consideration of the novel type of autotransformer changes the current distribution due to the change of configuration of the electric railway feeding systems, it is essential to consider the improvement of the fault locating algorithm. Therefore, novel fault locating algorithm reflected the new system parameters is proposed and performance of the proposed algorithm is verified with the fault analysis in this dissertation.