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Abstract
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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?–I? 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? with respect to I?. 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 2ms in all the tests.
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