Longitudinal differential protection is among the most important protection mechanisms in the short transmission lines. During energization, some factors might disrupt the performance, and on-line fault detection using the longitudinal differential relay might result in an undesired interruption. Therefore, in this paper, a new method is proposed to detect the fault current from the switching currents, and other transient and loading conditions accurately. For this purpose, a new mathematical and performance method is proposed based on the Clarke transformation to extract the features, classification, and instantaneous patterns of the calculations. Therefore, a unique operating characteristic in I_α–I_β framework is suggested to detect the internal fault from the external fault and other transient conditions by point -to -point checking and tracking the trajectory I_α with respect to I_β. A typical power transmission network is simulated in the MATLAB software to validate the proposed method. Furthermore, the actual fault on the real transmission line GT918 from Bushehr network in Iran's power grid is analyzed. Simulation and practical test results indicated high speed, stability, reliability, and accuracy of the proposed method in detecting the internal fault in the short transmission lines. The internal fault is accurately detected fewer than 2 ms in all the tests.

纵向差动保护是短输电线中最重要的保护机制之一。在通电过程中，某些因素可能会破坏性能，并且使用纵向差动继电器进行在线故障检测可能会导致意外中断。因此，本文提出了一种从开关电流以及其他暂态和负载条件下准确检测故障电流的新方法。为此，提出了一种基于Clarke变换的新数学和性能方法，以提取计算的特征，分类和瞬时模式。因此，一个独特的操作特性在我_α -I _β提出了一种框架，通过点对点检查和跟踪相对于_Iβ的轨迹_Iα，从外部故障和其他瞬态条件中检测内部故障。在MATLAB软件中对典型的输电网络进行了仿真，以验证所提出的方法。此外，分析了伊朗电网中布什尔网络的真实传输线GT918上的实际故障。仿真和实际测试结果表明，该方法具有较高的速度，稳定性，可靠性和准确性，可用于检测短输电线内部故障。在所有测试中，不到2 ms即可准确检测到内部故障。