基于压缩感知理论和二阶微分法的贯通式同相AT牵引供电系统牵引网输电线路单端保护方法

Single-ended Protection Method for Transmission Line of Traction Network of Co-phase AT Power Supply System Based on Compressed Sensing Theory and Second Order Differential Method

贯通式同相牵引供电系统能彻底解决电分相及负序问题,是目前高速铁路研究的重要方向。压缩感知技术在突破奈奎斯特采样定理对采样个数要求的同时能增强信号时聚性,并对故障暂态信号进行降噪。二阶微分法可以放大故障特征,解决高阻接地故障时故障分量过小而导致保护拒动的问题。提出用压缩感知技术对故障电流的线模信号进行压缩重构,再由二阶微分法处理压缩感知重构出的故障电流线模信号得到其首波头的幅值,将该幅值与预设阈值比较进而判断出故障位置的保护方法。利用PSCAD/EMTDC平台搭建贯通式同相AT牵引供电系统模型,通过改变故障位置、故障初始角及过渡电阻进行仿真实验,实验结果验证了该保护方法的有效性。

The co-phase traction power supply system can completely solve the problems of electrical phase separation and negative sequence,which is an important direction of current high-speed railway research.Compressed sensing technology not only breaks through the“Nyquist”sampling theorem for the number of samples required,but also enhances the time convergence of the signal and de-nosing of the fault transient signal.The second order differential method can amplify the fault characteristics and solve the problem that the fault component is too small in the case of a high-resistance ground fault,which causes the protection to fail.In this paper,the compressed sensing technology is used to compress and reconstruct the line mode signal of the fault current,and then the second order differentiation method is used to process the line mode signal of the fault current reconstructed by the compressed sensing to obtain the amplitude of the first wave head.The preset threshold value is compared with above obtained amplitude,and then the protection method of the fault location is determined.Using the“PSCAD/EMTDC”platform to build a co-phase AT traction power supply system model,a large number of simulation experiments were performed by changing the fault location,the fault initial angle and the transition resistance,and the experimental results verified the effectiveness of the protection method.