Buddy bidirectional supply for traction substations

Most traction substations are equipped with 12-pulse passive rectifiers. Therefore, Total Harmonic Distortion (THD) of the input current is high, and feedback of braking power into the grid is not possible. Also, the overhead line voltage fluctuates seriously with varying loads. Imtech has developed a bidirectional supply for traction substations based on IGBT technology. The power electronics consist of a hysteresis controlled line-side converter. This results in low THD in the input AC current and low ripple on the output DC voltage. A system concept is developed for existing substations to add such an active converter to the already installed 12-pulse passive rectifier. In feed-in operation the system operates as a regular 12-pulse passive rectifier. In case of a reverse power flow due to braking operation on the track, the converter is activated, thus making feedback mode possible.