Operational and Energy Benefit Analysis of a Modular Multilevel Converter-Based Bidirectional Continuous Railway Feeding System

Neutral sections in 25 kV AC railways require trains to coast with the main circuit breaker open, which temporarily interrupts traction. Regenerative-energy use also varies with the power-receptive capacity of the feeding section and the upstream grid. The operational and energy effects of a bidirectional continuous feeding system based on a modular multilevel converter (MMC) were quantified using a one-dimensional train-motion model and an energy-balance calculation. A 300 km/h train was evaluated for effective de-energized lengths of 200–800 m and gradients of 0–15‰. At 400 m, speed loss increased from 1.28 km/h on level track to 3.23 km/h at 12‰ and reached 7.50 km/h at 800 m and 15‰. The calculated delay to initial-speed recovery remained below 0.4 s. When regenerative receptivity increased from 0.32 to 0.88, the reduction in normalized net supply energy ranged from 5.8% to 18.6% as the recoverable braking-energy ratio varied from 0.10 to 0.30. The reduction was 12.0% at a ratio of 0.20. Field validation requires synchronized measurements of train operation and feeder power to replace the assumed vehicle parameters and receptivities.