城轨直流牵引供电多回流路径耦合建模及回流安全参数动态分布

Multiple Reflux Paths Coupling Modeling for Urban Rail DC Traction Power Supply and Dynamic Distribution of Reflux Safety Parameters

当前,城轨直流牵引供电系统回流安全已成为影响线路安全运行的关键问题之一。为研究多回流路径耦合对回流安全参数及周边关键金属工程的影响,该文提出多回流路径耦合情况下直流牵引供电系统动态仿真模型,构建多回流路径耦合矩阵,建立多回流路径耦合情况下多区间回流安全参数动态分布计算方法,实现回流安全参数动态分布规律分析。基于实际线路参数,分析了不同类型多回流路径耦合时钢轨电位和杂散电流分布规律。研究结果表明,该文所提出的方法可有效模拟多回流路径耦合情况下回流安全参数动态分布及对周边关键金属工程的影响;针对走行轨回流不畅及多回流路径耦合,分别提出并联电缆及单向导通控制的治理方法,并基于该文所建立的模型进行仿真分析,验证了其有效性。

DC traction power supply systems are usually adopted in urban rail transit.Rail potential and stray current are the reflux safety parameters of the system,which have become the key problems affecting the safe operation of urban rail lines.Excessive rail potential seriously affects the safety of traction power supply system,and stray current will flow through the surrounding ground and buried metal pipeline,causing serious electrochemical corrosion to the key buried metal projects around.With the deterioration of local or regional insulation of the running rail,the coupling operation of multiple reflux paths is obvious.In general,the modelling and analysis of reflux safety parameters have mainly focused on the urban rail system itself.In order to study the influence of multiple reflux paths coupling on reflux safety parameters and surrounding key metal projects,this paper proposes a dynamic simulation model of DC traction power supply system under multiple reflux paths coupling.Firstly,based on the structure of DC traction power supply system with multiple reflux paths coupling,the dynamic simulation model of DC traction power supply system with multiple reflux paths coupling is established.The model introduces coupling sections at both sides of poor reflux and adds multiple reflux paths between these coupling sections,described by means of the matrix of multiple reflux paths coupling.Then the dynamic distribution calculation method for multi-interval reflux safety parameters under multiple reflux paths coupling is established.Finally,the distribution of rail potential and stray current under different types of multiple reflux paths coupling is analyzed based on the actual line parameters.Simulation results show that,when the running rail insulation deterioration coupling,the amplitude of the rail potential at the deteriorating position will decrease,stray current generates a sudden change,the whole line rail potential will be pulled down or raised,and the maximum value of whole line stray current increased to-800.1 A.When buried metallic pipe coupling,the maximum value of the total stray current leaking into the pipe is 32.6 A.When parallel cable in high resistance sections of running rail coupling,the maximum value of the rail potential is significantly reduced from 185.3 V to 156.8 V after the parallel cable treatment,and the peak-adjusted operating schedule does not have an impact on the effectiveness of the treatment.When the surrounding grounding grid coupling,the grounding current is negatively correlated with the rail potential at the coupling point,the maximum value of the grounding current is 14.9 A.When UCD is set up on the multiple reflux paths,the direction of the grounding current only exists in the positive direction,which effectively reduces the overall current flow on multiple reflux paths.The following conclusions can be drawn from the simulation analysis:(1)The model comprehensively considers the coupling relationship between the DC traction power supply system of urban rail and the key metal engineering around it,and based on the multiple reflux paths coupling matrix,it can effectively describe the multiple reflux paths,and realize the unified modeling of multiple reflux paths and complex operating conditions.(2)In the case of multiple reflux paths coupling,the potential and current of the urban rail system and other surrounding metal structures change significantly,so the multiple reflux paths coupling should be considered comprehensively when analyzing the dynamic change of the safety parameters of urban rail system.(3)The model can be applied to the analysis of rail potential and stray current treatment effect.The effectiveness of treatment methods such as parallelling cable in high-resistance section of running rail and setting UCD on reflux path shave been verified.