CDF-Based Capacity Estimation Method for Stationary Regenerative Solution in Parallel-Fed DC Urban Subway Transit

The energy consumption of DC urban subway transit (UST) has attracted an increasing amount of attention, and various studies have focused on improving the energy use of USTs by increasing the energy efficiency or reducing the energy consumption. However, the amount of regenerative energy that can be re-utilized and the capacity of the regenerative device for re-utilization have not been extensively discussed. To simply compute the specification of the sustainability improvement facilities for a parallel-fed UST system, this paper proposes current distribution factor (CDF) based analysis that reflects the mobility and power variation of the vehicle loads in UST system. The CDF set are derived based on the electrical distance between the vehicle load and each substation, and the powerflow method with the CDF set provides an intuitive solution to analyze supplied or regenerative power flow in the parallel-fed DC UST system. Based on the actual UST line data, the convergence characteristic of the proposed algorithm was verified and the capacity of the regenerative device was calculated for peak and non-peak headway conditions.