FBD-based control in active DC-traction substations

This paper is concerned with the implementation of the Fryze-Buchholz-Depenbrock theory in the control of an active DC-traction substation. The active DC-traction substation taken into consideration is obtained by adding a specific system for active filtering and regeneration to a classical DC-traction substation with twelve-pulse uncontrolled rectifier. The main component is a voltage source inverter-based shunt active power filter with suitable connecting circuits, whose control allows increasing the energy efficiency of the system by improving the power quality in traction regime and achieving the energy recovery during the braking regime. In order to obtain a good quality of the current injected into the power supply in both operating regimes, the point of common coupling on the AC-side is placed in the primary of the traction transformer and the indirect control of the current upstream the point of common coupling is the adopted control solution. The reference current is provided in accordance with the Fryze-Buchholz-Depenbrock definition of the active current, so that almost unity power factor is obtained. The simulation results prove the proper operation of the whole system, the natural transition from a regime to the other one and a total harmonic distortion factor of the supply current below 3% in both operating modes.