Dynamic simulation of the DC traction power system considering energy storage devices

Models of different parts of the DC power system including the energy storage devices-supercapacitors (SCs) are discussed in this paper. Charging and discharging voltage thresholds and SOC (State of Charge) should be taken into consideration when establishing the SCs model. Also the algorithm to calculate the power flow of the system changes after the addition of SCs. Combined with the states of traction network, the control strategy of SCs is analyzed in detail. The dynamic simulation is based on the Chain-rule Reduction of Ladder Circuit Jacobian Matrices method. To compare the energy saving and voltage stabilization effects, three equipment installation conditions-with braking resistors (BRs) only, with SCs only, with neither of them, are set in this paper. The simulation program is edited in Matlab with m language. Finally with this program the simulation results of a certain metro line in three conditions were compared and analyzed, and all effects were achieved.