Development and implementation of a 1.5 MW inverter and active power filter for the injection of regenerated energy in a Spoornet substation

This work discusses the implementation of a 1.5 MW system that injects the regenerated energy, caused by the braking action of electric trains, back into the Eskom supply. At present this energy is dumped into resistor banks and goes to waste as heat. For the intervals that the train is not regenerating energy, the system operates as an active power fitter. An overview of the system is provided as well as further details on the series-stacked inverter, injection transformer, measurement system and protection in the system. Simulation results show the operation of the system.