In order to ensure the necessary level of electrical isolation between neighboring substations, it is essential that the neutral sections should be installed. The neutral section provides the necessary electrical isolation between the substations. An added benefit of such configuration is that it can offer the flexibility of the changing the source of power to certain feeder segments. If necessary, individual feeder segment can be cut off from its main power while the continuation of the feeder service is guaranteed by a nearby substation. However, the existence of the neutral section in the feeder line means the loss of traction power when an electric locomotive passes through the section. Because of no traction power, the speed of the train cannot be regulated. Usually, the speed slows down during the passage of the section. Such loss of the speed might introduce a significant amount of delay in the total travel time of the train. Moreover, if the speed of the locomotive happens to be almost standstill when it enters the section, then there is a good chance to see that it would stop in the middle of the section. Then, it is unable to escape the section unless a helping locomotive is to be dispatched there to draw the train out of the section. Therefore, there has been much attention and research effort into the issue of ensuring proper power supply to the section. In this paper, an improved approach to the power supply system to the neutral section is proposed. In this approach, a modern power electronics topology of MMC (Modular Multi-level Converter) is introduced as part of the main power supply system. The effectiveness of the proposed system was verified through realistic real-time simulation results.
In Kwon Park, Byeong-Gon Lee, Joorak Kim, and Chang-Mu Lee, "An improved power supply system for neutral sections in railway electric power systems," in COMPRAIL 2018, Lisbon, Portugal, 2018.
KEYWORDS: Railway electric power system, Neutral section, Modular multi-level converter, phase-shift control