Research and Application for Active Detection of Burial Depth on 500kV Ultra-high Voltage Live Submarine Cable

It is known that the main cause of the failure for submarine cable is damaged by external forces. As a result, regular inspection of the buried depth about submarine cable is extremely important to know the risk points and eliminate this hidden danger. Under normal circumstances, the detection of the burial depth of submarine cable requires a power outage, and a special signal with a low-voltage and different frequency should be injected onto the cable, so that the electromagnetic field of this signal could be picked up by the detection equipment to obtain the burial depth. For some key links, the submarine cables are always energized and in service, so it is not feasible to introduce a tone onto the power cables. In this paper, a device which could directly inspect the 500kV ultra-high voltage submarine cables with the cable keep running. The electromagnetic induction coil and collector of the detection device are redesigned, so that it can directly identify the signal of strong electromagnetic field with the voltage of 500kV, to avoid any saturation distortion. Using this device, the burial depth of running submarine cable could detected without power outage and additional detection tone injected. Hainan Power Grid Interconnection Projects are the only power links with great significance between Hainan Island and the mainland of China, and It is very difficult to shut down the power of these 500kV submarine cables. In December 2019, this detection equipment was installed onto the Remote Operated Vehicle to inspect the burial depth of the cables without a power outage. The result shown that it worked well and achieved great success.