城市轨道交通直流自耦变压器牵引供电系统故障保护研究

Fault Protection of DC Auto-Transformer Traction Power Supply System for Urban Rail Transit

直流自耦变压器(DCAT)牵引供电系统凭借良好的轨道电位和杂散电流治理能力在城市轨道交通领域具有广泛应用前景。然而当直流牵引供电网络发生短路或DCAT自身故障时,传统DCAT由于缺乏故障保护能力,其直流支撑电容和谐振电容可通过故障处放电,进而导致DCAT器件损坏和故障扩散等。为此该文提出了一种故障保护型直流自耦变压器(FP-DCAT),在分析FPDCAT工作原理基础上,研究了FP-DCAT系统的故障机理,并提出相应的故障保护方案。FP-DCAT故障保护后系统仍可正常运行,但轨道电位和杂散电流却可能因故障FP-DCAT切除而增大,因此研究了故障保护对系统轨道电位和杂散电流的影响。最后,仿真结果表明FP-DCAT系统可有效地实现故障保护,且系统轨道电位和杂散电流变化与理论分析一致,确保FP-DCAT系统在城市轨道交通中安全可靠的运行。

DC auto-transformer(DCAT)traction power supply system has a promising application prospect in urban rail transit because of the rail potential and stray current mitigation.However,the traditional DCAT may lack the sufficient fault protection capability,when DC traction power supply network short circuit or device failure of DCATs.DC-link capacitors and resonant capacitor of DCAT may discharge rapidly through the fault,which leads to the device damage of DCAT and fault pervasion.Therefore,the fault protection DC auto-transformer(FP-DCAT)is proposed in this paper.With the research on topology and control of FP-DCAT,the fault protection schemes of FP-DCAT system for typical faults are studied in detail.FP-DCAT system may operate normally after fault protection,but the rail potential and stray current of system may increase due to the removal of fault FP-DCAT.Thus the effects of fault protection on the rail potential and stray current are analyzed.Finally,the simulation results show that FP-DCAT system achieves fault protection effectively,and the variation of rail potential and stray current due to fault protection is consistent with the theoretical analysis,which ensures the high safety and reliability of FP-DCAT system applied to urban rail transit.