A Thyristor-Based Auto-Passing Neutral Section Scheme With Auxiliary Transformers for AC Electrified Railway

The further development of high-speed and heavy-haul railways is restricted by the existence of neutral sections. Traditional thyristor-based auto-passing neutral section schemes can make the train pass through neutral sections with power supply and reduce its speed loss. However, the electric locomotive still exists a power interruption time of several milliseconds and may confront with the problem of inrush current. To address the issues of traditional thyristor-based schemes and transfer the neutral section voltage more smoothly, a modified thyristor-based scheme is proposed in this article. By adding auxiliary transformers and additional switches, two intermediate voltages with unchanged amplitude are introduced. The neutral section voltage is switched step by step between the voltages of two feeders, with a smaller phase change each time. The total power interruption time of the train is further shortened, and the inrush current is effectively avoided. The construction idea and the working characteristics of the proposed scheme are introduced. Furthermore, the effectiveness and the superiority are verified by the simulation and experimental results. The proposal of the modified thyristor-based scheme provides a new thought to deal with the problem of train passing neutral section in ac electrified railway.