±400 kV 直流海缆悬空段涡激振动响应分析算法设计与疲劳寿命评价

High-voltage submarine power cables in service, subject to ocean currents for a long time, may produce mechanical fatigue failure due to vortex vibration, threatening the operational stability of submarine power transmission. Therefore, it is necessary to study the response of vortex vibration of the cable and its fatigue evaluation method in different marine environments. In this paper, based on the ±400 kV flexible DC transmission cable supporting Rudong offshore wind farm, based on MATLAB, the finite element method is used to analyze its eddy-excitation vibration characteristics under different seawater flow rates, different lengths of suspended segments, and different seawater temperatures, as well as its fatigue state evaluation after vibration. And the line shape of the suspended span section of the submarine cable obtained from the simulation is compared with the theoretical calculation value. The error is 0.16%, which verifies the accuracy of the simulation model. It is concluded that, when the seawater flow rate increases, the vibration amplitude of the cable increases, and the amplitude reaches the maximum value when the excitation frequency and the intrinsic frequency are the same, moreover, the vibration amplitude decreases when the flow rate increases again; when the length of the cable overhanging section increases in the range of 0~30 m, the vibration amplitude increases and the amplitude is maximum at the time of resonance. The resonance amplitudes at each overhang length have the same trend, and all produce amplitude maxima at the center; when the seawater temperature changes within the normal range, the impact on the vibration amplitude of the cable is in the millimeter level, and the vibration amplitude is in the millimeter level. It can be approximated that the seawater temperature does not affect the vibration amplitude of the cable. The fatigue life of the armor layer and the alloy lead jacket layer of the submarine cable was studied and analyzed. The results show that there is no fatigue damage to the armor layer even under resonance conditions, and it can be assumed that no fatigue damage occurs to the armor layer; for the alloy lead jacket, the fatigue life is about 65.45 years with a seawater flow rate of Lianyungang(a city in China) route and an overhanging section of 25 m.