A Fault Phase and Line Selection Method of DoubleCircuit Transmission Line on The Same Tower Based on Transient Component

The double-circuit transmission line on the same tower has been widely used in Chinese UHV transmission lines due to its advantages of less ground, lower investment and transmission efficiency. However, the fault condition is more complicated than on the single transmission line, making the setting, fault phase and line selection of the relay protection complicated. Based on the analysis of the coupling relationship between six phases, a fault phase selection (FPS) method based on transient component is proposed. The wavelet transform is used to extract the transient energy of the fault current component and a morphological filter with flat structure element to remove high-frequency noise and eliminate the sharp component of the waveform. The transient energy magnitudes are compared to identify fault type and select fault line. The effectiveness of the method was verified under different fault types, fault location, fault time and transition resistance using ATP-EMTP.