Grid connected improved sepic converter with intelligent mppt strategy for energy storage system in railway applications

In order to increase the utilization rate of regenerative braking energy, reduce the operation cost and improve the power quality of traction power supply system in high-speed railway. This paper presents a grid-connected improved SEPIC converter with an intelligent maximum power point tracking (MPPT) strategy tailored for energy storage systems in railway applications. The proposed system enhances power conversion efficiency and stability by integrating an optimized SEPIC topology with an adaptive MPPT algorithm. The solar PV system supplies voltage to the inverter via an Improved SEPIC converter. A smart MPPT technique is used to regulate the DC bus voltage and control the Improved SEPIC converter. The wind energy conversion system (WECS), featuring a DFIG, performs AC-DC conversion with the help of a PWM rectifier, and the rectifier is managed by a PI controller. The converter's output is fed to the grid through a single-phase VSI, which converts the DC voltage into AC. An LC filter is used to improve the inverter's output. The combined power from the PV and WECS sources is stored in the battery through a bi-directional battery converter. Power from both the battery and the AC output from the single-phase VSI is then injected into the power grid, which supplies energy to the train for its operation. Compared to conventional SEPIC converters, the improved topology reduces voltage stress by 25% and increases efficiency by 97%, ensuring reliable energy storage and grid synchronization. Furthermore, the intelligent MPPT strategy improves tracking speed by 37.5% under dynamic conditions, leading to enhanced energy utilization and reduced response time. Simulation and experimental results (DSPIC30F4011 controller) validate the superior performance, demonstrating its potential for real-world railway applications.