Unified AC/DC power flow for system simulation in DC electrified transit railways

The paper presents the improvements of a commercially available train simulator, the Energy Management Model (EMM), to evaluate the power flows in DC electrified transit railways. The sequential Gauss-Seidel power flow program used in EMM has been replaced by a unified Newton-Raphson AC/DC power flow to speed up the calculations. A precise model of the uncontrolled bridge rectifier with commutation impedance has been applied to the power flow formulation. Effects of regenerative braking on rectifier operations are also taken into account. Both the improved and the original train simulators have been tested on the Blue Line of Taipei Rapid Transit System which is under construction. Simulation results show that the proposed power flow program, with excellent convergence characteristics and accuracy, is of great value for train simulation.