Fault Location On DC Transmission Line Based On Mathematical Morphology

With the development of marine renewable energy and distributed generation program, VSC-HVDC technic will be used more frequently in undersea cable project. The cable used in the system was placed underground or undersea, the exact location of the fault point become difficult to be found once failure happened. Therefore, it is of great significance to develop a method to judge the fault point of power cable both quickly and accurately, which was discussed in detail in this article as followed. 1. The fault traveling waves on the transmission lines of VSC-HVDC system and hybrid HVDC system were discussed and the mechanism of production along with the characteristics were further described. The fault waves in different form, distance and transient resistance were simulated with PSCAD/EMTDC. 2. Based on the study of fault waves in DC transmission systems, a method of single-terminal fault distance measurement with two-terminal data was presented. The fault location analysis would be classified by neural network pattern recognition toolbox at first, and mathematical morphological gradient algorithm would be further used to obtain the time of fault occurrence. The difficulty, due to the serious traveling wave dispersion of underground cable, of accurately measuring the arrival time of the fault traveling wave on long distance transmission line was solved. 3. Mathematical morphological gradient algorithm was used to obtain the time of fault occurrence, which is of the most importance in distance measurement of traveling waves. Mathematical morphological gradient algorithm can be high in accuracy, not affected by transient resistance, which have been demonstrated in experiments.