近年来，随着城市轨道交通的快速发展，规模日益增大，能耗也快速上涨。其中牵引能耗占轨道交通总能耗近一半，为其主要能耗途径。而柔性直流牵引供电系统可以通过灵活调控系统潮流，实现机车之间的能量消纳，减小牵引所数量，减小牵引系统能耗。而钢轨电位作为保障城轨直流牵引供电系统的安全的必要条件，其在柔直系统中产生了许多新的特性有待研究。本文围绕钢轨电位的建模与计算方法、分布特性分析、抑制控制策略以及线路装置与参数等多个方面展开研究，具体成果如下：第一，针对传统潮流计算方法效率低、速度慢的缺陷，建立了两阶段接触网与回流网模型，并基于此提出了两阶段高效潮流与钢轨电位计算方法。基于工程近似等效、参数折合与替代定理，在保证潮流与钢轨电位计算精度的同时，有效提升了其计算效率，缩短了计算时间，便于后续研究。第二，基于两阶段接触网与回流网模型，理论推导出了在柔性直流牵引供电系统中钢轨电位分布特性与牵引所端口电压的关系式，提出了中心电压这一概念，并给出了其精确与工程上的近似计算公式。通过MATLAB与PSCAD仿真从多种工况下分别验证了该结论的正确性与有效性，为后续钢轨电位抑制控制策略的提出提供了理论基础。第三，针对N方式与N-1方式运行的柔性直流牵引供电系统特性，分别设计了适合的钢轨电位本地控制策略与钢轨电位协同控制策略。其中本地控制策略快速精准，适用于N方式；协同控制策略调动周边牵引所能力实现退出运行的牵引所处钢轨电位的控制，适用于N-1方式。同时将钢轨电位协同控制策略运用在考虑牵引所功率限幅特性的柔直系统中，拓展了其适用范围。第四，考虑到OVPD与系统绝缘损坏对上述结论的影响，分别研究分析了多种新的工况下，前述钢轨电位分布特性产生的变化，并提出了与OVPD相配合的钢轨电位设备控制策略，以及绝缘损坏情况下钢轨电位变化特性与识别方法。拓宽了本文结论适用范围，增强了本文结论的适用性。
In recent years, with the rapid development of urban rail transit, the scale of it is increasing, and energy consumption is also rising rapidly. Traction energy consumption accounts for nearly half of the total energy consumption of rail transit, making it the main energy consumption path. The flexible DC traction power supply system can flexibly regulate the system power flow, achieve energy absorption between locomotives, reduce the number of traction substations, and reduce the energy consumption of the traction system. As a necessary condition to ensure the safety of DC traction power supply systems for urban rail transit, rail potential has generated many new characteristics in flexible and straight systems that need to be studied.This paper focuses on the modeling and calculation methods of rail potential, distribution characteristics analysis, suppression control strategies, and line devices and parameters. The specific results are as follows:Firstly, aiming at the shortcomings of traditional power flow calculation methods such as low efficiency and slow speed, a two-stage catenary and return current network model is established, and based on this, a two-stage efficient power flow and rail potential calculation method is proposed. Based on the engineering approximate equivalence, parameter reduction, and substitution theorems, while ensuring the accuracy of power flow and rail potential calculation, it effectively improves its calculation efficiency, shortens the calculation time, and facilitates subsequent research.Secondly, based on a two-stage catenary and return network model, the relationship between the rail potential distribution characteristics and the traction station port voltage in a flexible DC traction power supply system is theoretically derived. The concept of center voltage is proposed, and its accurate and approximate engineering calculation formula is given. The correctness and effectiveness of this conclusion were verified through MATLAB and PSCAD simulations under various operating conditions, providing a theoretical basis for the subsequent proposal of rail potential suppression control strategies.Thirdly, according to the characteristics of flexible DC traction power supply systems operating in N-mode and N-1 mode, suitable rail potential local control strategies and rail potential cooperative control strategies are designed respectively. The local control strategy is fast and accurate, suitable for N-mode; The collaborative control strategy mobilizes the ability of peripheral traction to achieve control of the rail potential at which traction exits operation, and is applicable to N-1 mode. At the same time, the collaborative control strategy of rail potential is applied to the flexible and straight system considering the power limiting characteristics of the traction station, expanding its applicability.Fourthly, considering the impact of OVPD and system insulation damage on the above conclusions, the changes in the distribution characteristics of rail potential under various new operating conditions were studied and analyzed, and a control strategy for rail potential equipment in conjunction with OVPD was proposed, as well as the characteristics of rail potential changes and identification methods under insulation damage. Expanding the scope of application of the conclusion in this article and enhancing its applicability.
