Longitudinal protection method based on reverse traveling wave and signal processing for UHVDC power transmission line

At present, the longitudinal protection of the DC transmission line is simply superimposed without considering the strong nonlinearity of the DC transmission system, so it has adaptability problem in actual engineering. Aiming at this problem, a new method of longitudinal protection is proposed. From the perspective of the adaptability of the protection method, a signal linearization processing technique based on the description function method is proposed. By analyzing the transmission characteristics of the reverse traveling wave in a time window after the internal and external faults occur in the DC transmission line, it is found that the similarity between the reverse traveling wave waveforms of the two ends of the line is higher du-ring the internal fault, while it is lower during the external fault. Then a longitudinal protection method based on reverse traveling wave is proposed, which uses Hausdorff distance algorithm to measure the similarity of the reverse traveling waves at two ends of the line and constructs the fault identification criteria for DC power transmission lines. The simulative results show that the proposed method can reliably distinguish internal and external faults in DC lines, and has high sensitivity when grounding fault with high resistance occurs. © 2020, Electric Power Automation Equipment Editorial Department. All right reserved.