城市轨道交通接触网短路阻抗测试及整定计算装置的研制

Development of Short-Circuit Impedance Testing and Setting Calculation Device for Urban Rail Transit Catenary

[目的]城市轨道交通接触网的线路阻抗受多种因素(如线索材料、线路长度、周边环境等)的显著影响,导致不同线路及不同时段的阻抗差异显著。然而,在整定计算过程中,常依赖于经验公式进行估算,这往往导致整定值不够精确,进而影响了保护装置的选择性与灵敏性。当系统遭遇短路故障时,可能会出现误动或拒动的情况,带来较大的安全隐患。因此,研制一种能够准确测试接触网短路阻抗并进行整定计算的装置显得尤为重要。[方法]提出了一种低压短路试验方法。该方法在接触网末端设置短路点,通过在线路首端施加低压直流电的方式,实现对短路阻抗的测量。采用高精度的双通道同步采样技术获取电压与电流的精确采样值,并基于RL简化双边供电模型,结合牛顿迭代法,研究出了一种指数曲线拟合求解线路阻抗的新方法。此外,通过开发集参数配置、整定计算于一体的软件,成功集成了接触网阻抗测量及整定计算装置。[结果及结论]该装置不仅具备参数配置、线路阻抗求解等功能,还能对短路点的电流变化进行仿真分析;能够实现根据不同线路和环境条件的实时测量,显著提高了线路阻抗测量的准确性,为整定计算提供了坚实的数据支持和重要参考。通过实际算例验证了线路阻抗计算和短路电流结果的准确性,充分证明了该方法的可行性和有效性。

[Objective]The line impedance of urban rail transit catenary is significantly affected by many factors such as wire material,line length,surrounding environment,etc.,resulting in significant impedance differences between different lines and different time periods.However,in the setting calculation process,assessments often rely on empirical formulas,leading to inaccurate setting values and affecting the selectivity and sensitivity of the protection device.When the system encounters a short-circuit fault,false operation or refusal to operate may occur,posing a great safety hazard.Therefore,it is particularly important to develop a device that can accurately test the short-circuit impedance of the catenary and perform setting calculations.[Method]A low-voltage short-circuit test method is proposed.The method sets a short-circuit point at the end of the catenary and realizes the measurement of short-circuit impedance by applying low-voltage direct current at the head end of the line.A high-precision dual-channel synchronous sampling technology is used to obtain accurate sampling values of voltage and current,and a new method for solving line impedance by exponential curve fitting is developed based on RL simplified bilateral power supply model and combined with Newton iteration method.In addition,by developing a software that integrates parameter configuration and setting calculation,the catenary impedance measurement and setting calculation device is successfully integrated.[Result&Conclusion]This device is not only capable of parameter configuration and line impedance solving,but also can simulate and analyze the current changes at the short-circuit point.It can realize real-time measurement according to different lines and environmental conditions,significantly improves the accuracy of line impedance measurement,providing solid data support and important reference for setting calculations.The accuracy of line impedance calculation and short-circuit current results is verified through actual examples,thus the feasibility and effectiveness of this method is fully proved.