DC traction grid modernization strategy to support EV chargers integration, enhance grid performance and profitability

DC traction grid modernization strategy to support EV chargers integration, enhance grid performance and profitability. This paper proposes a multi-stage modernization strategy based on return on investment (ROI) analysis for integrating EV chargers, battery storage and renewable energy sources (RES) into DC traction grids. A power converter interface (PCI), which consists of multiple power converters and a Smart Grid-based integration concept is proposed for modifying the existing infrastructure. The approach combines technical and economic considerations to support decision-making under varying regulatory and operational conditions. The effectiveness of the approach is evaluated using representative cost models, showing that additional services enabled by the PCI, such as EV charging, power quality improvement and RES integration, can achieve ROI values in the range of 10-20%, depending on electricity tariffs, penalty coefficients and utilization levels. The results indicate that, under suitable conditions, staged modernization of traction substations can improve power quality, reduce overloads and increase infrastructure utilization.