Dynamic Performance Analysis, Optimization, and Verification of DC Auto-Transformer System With Rail Potential and Stray Current Emulator

DC auto-transformer (DCAT) traction power supply system has been studied to suppress the rail potential and stray current for urban rail transit (URT), which generally takes the constant train load to simplify the analysis. However, in practice, the train is a non-linear load with frequent accelerating and braking, which leads to the rail potential and stray current changing with different train operating conditions. Therefore, the dynamic performance analysis and optimization of DCAT system are discussed in this article. The rail potential and stray current dynamic emulator (RSDE) for DCAT system verification is proposed because it is difficult to test the DCAT system directly in the actual URT. Based on the configurations and operation principles of both DCAT system and RSDE, the comparisons between DCAT system and the existing system on the rail potential and stray current are discussed. Meanwhile, considering the train dynamic performance, define the dynamic performance index (DPI) to evaluate the effects of the DCAT system on the rail potential and stray current mitigation and optimize the DCAT system with DPI. Finally, the correctness and effectiveness of DCAT system on the rail potential and stray current mitigation are validated by the simulation results and experimental verification.