Inverter Operating Characteristics Optimization for DC Traction Power Supply Systems

Compared with energy storage equipment based on supercapacitors, flywheels, or lithium batteries, inverters have obvious advantages in installation space, cost, reliability, and service lifetime. For this reason, regenerative inverters are increasingly installed in the substations of urban rail transit systems. They have controllable operating characteristics, but their impact on the energy saving and railway operation cost has not been fully studied. In this paper, based on the typical application scheme of regenerative inverters, the operating characteristics of the inverter including power limitation, start working voltage, and virtual internal resistance are introduced at first. A simplified power system model containing regenerative inverters and trains has been built. The impact of operating characteristics on the amount of regenerative braking energy and its distribution is analyzed. The inverter operating characteristics are optimized by a cost function considering total energy consumption, brake shoes wear, and inverter expense. A case study based on a multiple-train scenario is presented to validate the cost-saving performance. The work is expected to provide some guides for the design and optimization of the traction power supply system with inverting substations.