Modified DSC propulsion systems for efficient direct recovery of regeneration in 25-kV AC traction power supply

Direct recovery of regenerative power can offer several benefits for saving energy in ac electrified railways. However, the method directly disturbs the braking patterns of rail vehicles as well as the voltage levels of the traction power supply. To tackle these issues, this paper presents two methods involving a modification of the regeneration performance of ac propulsion systems. The first method enables propulsion systems to deliver maximum regenerative power without altering the rail vehicles' deceleration pace. It is influenced by the dynamic energy of decelerating rail vehicle to acquire suitable reference values of the electromagnetic torque, which instigate the propulsion system to maximize the regeneration. The second method is a voltage regulator for propulsion systems to eliminate excess voltage rises caused by the regeneration. The regulator is based on the theory of traction network receptivity against the regeneration. The receptivity concept is first formulated and then applied to develop a new flux referencing module that maintains the stator voltage levels in traction motors when regenerating. The methods are evaluated by simulations supported by real physical data. The results explicitly demonstrate the functionality and effectiveness of the methods.