Railway Electrical Smart Grids: An introduction to next-generation railway power systems and their operation.

In the last decade, the development of next-generation electrical smart grids (ESGs) has been one of the priorities in the field of electrical engineering, both for most of the research centers and for the industry. In short, an ESG consists of the integration of information technologies into the electrical system to improve its controllability. In traditional power systems, the control has been carried out only by the power plants and some elements of the grid (transformer tap-changers, compensation capacitors, and reactances), whereas, in the next-generation smart grids, most of the elements can respond to control orders from the system operator, which allows, for instance, for the integration of the distributed generation and the demand into the control schemes of the power system. Because of this improved controllability, ESG technologies promise a significant improvement in the capacity utilization, the reliability of the system, and the energy efficiency of the grid.