Research On Traveling Wave Ranging And Lightning Identification Of HVDC Transmission Line Based On Multi - Test Point

Ultra high voltage direct current transmission has large transport capacity, father transmission distance and usually crosses complex environment, so its failure probability is high. Actual operation data shows that transmission line fault takes up 50% of the total failure rate in the HVDC system failure, while the lightning stroke is the main cause of the transmission line fault. Therefore, it is very practically significant to research how to realize locating faults in UHVDC transmission lines quickly and accurately, to discern lightning fault types effectively and to take particular measures. A traveling waves fault location scheme that is avoiding traveling wave speed influence and fused several current measurements is presented in this paper, which is based on the analysis of the characteristics of traveling wave on UHVDC transmission lines failure, as well, the identification methods of shielding failure or back striking and fault lighting stroke or non-fault lighting stroke has been deeply studied, then the methods are proved the effectiveness by simulation analysis. The main work and results are as follows.Analysing the characteristics of the traveling wave fault on HVDC transmission line, integrating multiple current traveling wave shapes characteristic and its timing sequence to distinguish the fault section, eliminating those invalid time points in multiple measurements, and calculating the fault location which is avoiding the traveling wave speed via the double-end traveling wave fault location principle. The simulation analysis shows that the HVDC transmission line traveling wave fault location of multiple measurements which is avoiding the traveling wave speed has high locating precision and ability to tolerant high transition resistance, and individual multiple measurement points that have invalid time have no effect on the locating reliability.To analyze the failure mechanisms of back striking and shielding failure in HVDC transmission lines, it can be judged according to the head traveling wave’s polarity differences on two occasions, and achieve the back striking and shielding failure identification. The simulation analysis results show that the method of lighting stroke identification which depends on traveling wave’s polarity is effective, and also it can be based on any measurement’s head traveling wave polarity of the traveling wave to achieve the identification of the lightning stroke character.In order to accurately identify non-fault lightning, to analyze the lighting stroke and non-fault lighting’s time-domain waveform characteristic.Accordingly, the lighting disturbance distinguish algorithm is proposed in which the zero-mode currents data in break time window are normalized to be analyzed. Simulation results show that the algorithm can identify lighting disturbance correctly, when the time-domain waveform characteristics is not obvious, it can be used to judge the lightning disturbance by the measurements which are close to the location of the distance.