Fault location for overhead and cable hybrid DC line based on the energy transmission characteristics

This paper proposes a fault location method for overhead and cable hybrid line in VSC-HVDC system. Firstly, the energy transmission characteristics in overhead and cable hybrid DC line is analyzed respectively. Secondly, the change of energy ratio at both ends of the line with fault points is studied, a fault segment identification method based on the energy ratio of two ends is proposed, and the auxiliary criterion to prevent misjudgment of line connection point fault is given. On this basis, the relationship between the energy ratio and the fault distance is derived, and the fault location equation is established to locate the fault within the segment. In the paper, the influence of unsynchronous sampling data on fault location accuracy is also analyzed, and a simulation model is built using PSCAD/EMTDC to verify the effectiveness of the proposed fault location method for overhead and cable hybrid line in VSC-HVDC system.