Impact of Wayside Energy Storage on the Power Quality of 3 kV DC Traction Power Systems

The quality of supply in 3 kV DC traction networks is crucial in ensuring optimum electric train operation. Due to the variable nature of traction loads, along with the unavailability of traction substations, several power quality deviations occur, compromising the reliability of supply. With the growing need to operate heavy haul trains in 3 kV DC networks, along with emerging technologies available to improve the quality of supply from the utility to the traction loads, an investigation into the benefits of utilizing regenerative energy to stabilize line voltage and improve power quality is considered. This paper focuses on the implementation of a DC-DC converter with a wayside battery energy storage system to store regenerative energy produced by DC locomotives to sustain the power quality requirements of the network. The preliminary results of the simulation indicate an improvement in the DC line voltage, reducing low line voltage conditions, maximizing train operation, as well as improving the power factor, decreasing the risk of penalties from the utility supplier. Based on the findings discussed in this paper, the combination of technologies considered, proves to be a viable solution in improving quality of supply to electric locomotives in South African railways.