An Integrated System of Line Protection and Fault Location for Submarine Hybrid Line

Abstract

Based on the structure analysis and fault analysis of the hybrid line, this paper proposes an integrated system of protection and fault location which is suitable for the hybrid line. The system is composed of line protection relays on the ends of the hybrid line and section positioning devices on the ends of the cable. It collects three phase currents on both sides of the cable by using flexible optical current transformer which suits to be installed on the joint points. It calculates the differential current at the ends of the cable line through optical fiber and discriminates the fault is whether in or out of the cable line section. Also, it sends the result to the protection devices on both sides of the hybrid line. When the fault is in the cable, the reclosing function on both sides of the line is blocked immediately. In addition, the line protection relays on both sides integrate the traveling wave fault locating function. With receiving section signal, traveling wave fault location can locate the fault point accurately. With lots of simulation tests, it can be proved that the integrated system proposed in this paper can realize the hybrid line protection and precise fault location of the hybrid line. It can greatly improve the power supply reliability of the hybrid lines. At present, the system has been operated in 500 kV cross-linked polyethylene Zhoushan submarine cable hybrid line.