Distributed consensus-based secondary control of multi-terminal DC railway systems

Electrification of the transportation sector is one of the main pillars of the future decarbonized society. In this context, high-speed railway corridors are expected to reduce as much as possible their environmental impact while maintaining the safety and quality of service with minimum investments. In pursuing those objectives, the multi-terminal DC railway system may become the preferred paradigm. In contrast to conventional AC railway electrification schemes, the multi-terminal DC railway system requires the adoption of a control algorithm to establish suitable references for the power converters. This paper elaborates on a new consensus-based secondary control strategy, which can be implemented in a distributed fashion. In this approach, each power converter controller receives information from its nearest neighbors to adjust its operating point. A 600-km railway system, subject to realistic train traffic, is used to compare the performance of the proposed control strategy with that of purely local controllers. Numerical simulations evidence that the proposed distributed control scheme provides a compromise solution in terms of voltage drops and equalization of power converter loading, surpassing the performance of conventional state-of-the art controllers.