Detection and Classification of EHV Transmission Line Faults Based on Sign of Reactive Power

In the outdoor erected overhead transmission lines, the probability of occurrence of a fault is high and it might lead to unstable operation of the power system and interrupt the continuity of power supply. This work has proposed a methodology to detect and classify such transmission line faults based on the signs of computed reactive power. The sign of reactive powers at both ends of the transmission line is computed through the extracted fundamental components of voltage and current obtained through the DFT algorithm. The discrimination of fault and normal operating conditions is achieved based on the signs of reactive power at both ends of the transmission line. Further, a transmission line fault classification strategy has been developed with the signs of computed reactive power. The method developed has been tested on the designed two-machine transmission test system and modified WSCC-9 bus test system in the PSCAD/EMTDC and MATLAB tools for all types of short circuit faults at various locations on the transmission line, with and without fault resistance, sudden change in load, with noisy input signal, CT saturation conditions, etc. In all the cases, the proposed method ensures the accuracy of detecting and classifying transmission line faults.