System of 35 kV 3-core submarine power cable

Submarine power cables are important in power transmission for islands, sea platform and wind plant. They are lying under the sea and endure the threatening of anchor while there is no effective method to find the anchor damage in time. In order to solve the problem, the anchor damage detection of submarine power cable based on φ-OTDR is proposed. The frequency measurement range of φ-OTDR has been tested as 0–800 Hz which can satisfy the requirement of optical fiber vibration sensing in submarine power cable. An optical fiber vibration monitor system is realized and put into service in a 35 kV three-core submarine power cable laid between two islands in China. The anchor drop and anchor drag incidents have been simulated. The vibration data of calm sea, anchor drop and anchor drag have been obtained and analyzed. Analysis results indicate that there are differences between calm sea, anchor drop and anchor drag in energy and amplitude distribution, the faults can be identified according to the differences. The anchor damage detection method proposed in this paper provides a feasible scheme for the on-line monitoring of the submarine power cable, which can early warn and alarm the anchor damage to submarine power cables. This research work has test the frequencymeasurement range of φ-OTDR as 0~800Hz which can satisfy the requirement ofoptical fiber vibration sensing in submarine power cable. We have simulated theanchor drop and anchor drag incidents and have obtained the vibration data ofcalm sea, anchor drop and anchor drag. According to the data analysis, thereare differences between anchor drop and anchor drag in energy and amplitudedistribution in frequency. The faults can be identified according to thedifferences. Meanwhile, anchor drop threats the cable in short time, whileanchor drag in a long time. Because anchor drag is driven by the ship, and shipset out is usually slow. In real operation, the fault type should be identifiedaccording to the signal feature. In addition, the longitude and latitude of thefault can be obtained according to the optical fiber positioning and submarinepower cable route. The ships threaten to the cable can be identified by AIS,and be contacted with marine intercom in order to avoid further deteriorationof faults.