【作者】 汪佳；

【导师】 陈小川；

【作者基本信息】 西南交通大学 ， 电力系统及其自动化， 2012， 硕士

【摘要】 地铁采用直流牵引供电方式,钢轨兼作为牵引电流的回流线,由于钢轨与大地不可能达到绝对的绝缘,会导致一部分电流泄漏到大地中,这部分电流就称为杂散电流。杂散电流会对地铁周围埋地金属结构进行电化学腐蚀,缩短金属管线的使用寿命,降低建筑设施的强度,严重时会威胁到人员的安全。因此,建立杂散电流分布模型,预测地铁运营时杂散电流、轨道电位等电气量的分布,可以为杂散电流防护的设计施工及运营维护提供了一定的理论依据,以保证地铁的建设质量与安全运行。目前,一般采用单列车模型对杂散电流的分布进行分析。单列车模型建模过程中边界条件为一个变电所(单边供电)或两个变电所(双边供电),并且列车也只考虑从邻近的变电所取流,这些假设都与地铁实际运行情况不相符,导致计算结果与实际值有较大的误差。为了更好的反映地铁实际线路上各电气量的分布,本文以更接近于实际线路的“钢轨-排流网-埋地金属-大地”(四层地网结构)结构为基础,将列车和牵引变电所都看作是注入电流源对地下结构进行作用从而产生杂散电流,利用微元算法及叠加原理,得到了多列车运行下杂散电流、轨道电位等量分布的数学模型(多列车杂散电流模型)。在此基础上,利用Matlab仿真软件编程建立了相应的仿真模型,通过仿真对某地铁线路多列车运行时全线杂散电流等量的分布及地网参数的影响进行了分析。仿真结果表明：多列车杂散电流模型能较准确地反映地铁整条线路上的杂散电流分布。更多还原

【Abstract】 Metro adopts Direct Current (DC) traction for power supply, and rail, as the return line of traction current concurrently, cannot be absolute insulation with the earth. This causes part of the current to leak to the earth, which forms the alleged stray current. Stray current can cause electrochemical corrosion of the metal buried around the metro, shorten the service life of the metal pipes, reduce the intensity of the building facilities and even worse threaten the safety of the personnel. Therefore, the establishment of the stray current distribution model and the forecast of the electrical quantity distribution such as stray current, rail potential etc., when the metro is operating, can provide certain theoretical basis for the designation, construction, operation and maintenance of the stray current protection, to guarantee the construction quality and the operation safety.Currently, single-locomotive model is generally used in the analysis of the stray current distribution. The boundary condition is either one substation (one way feeding) or two substations (two way feeding) in the process of building single-section bus model. Besides, electric locomotive is only considered to obtain current from substation nearby. However, all these hypotheses do not match with the actual operation of the metro, which causes large errors between calculation results and the actual value.In order to better reflect the distribution of each electrical quantity in the actual metro lines, the thesis is based on "rail-drainage net-buried metal-earth"(underground structure with four layers), which is more closer to actual lines, and both the locomotive and traction substation are taken as injection current sources that affect the underground structures to produce the stray current. This thesis adopts micro-element algorithm and superposition principle to obtain the mathematical model (multi-locomotive stray current model) that inflects the stray current, rail potential and other quantities when multi-locomotive is operating. On this basis, it builds the corresponding simulation mode through Matlab simulation software. Based on the simulation, it analyzes the effect of the distribution of the full line stray current and ground network parameters under the situation of operating multi-locomotive in a metro line. Simulation results show that multi-locomotive stray current model can reflect the distribution of stray current in the whole line more accurately.更多还原