垂直洋流下500 kV海缆电热耦合场和载流量研究

Electric-thermal coupling and ampacity of 500 kV DC submarinecable under the action of vertical ocean currents

发展海上风电是实现“双碳”目标的重要举措。直流海缆是海上风电输电工程的重要装置,而海缆稳态载流量等研究对推动远海风电大规模开发具有重要意义。近年来高压直流海缆稳态载流量的相关研究考虑海洋环境因素较为单一且未充分考虑绝缘层温差的限制。文中建立了500 kV直流海缆与海水系统的电-热-流耦合模型,研究了单根和双极海缆在不同敷设方式下垂直洋流(垂直于海缆长度方向流动的洋流)流速,考虑绝缘层温差限制、双极不同间距等对载流量的影响。结果表明,相较于仅考虑线芯温度70℃限制,综合考虑绝缘层温差20℃限制的载流量更小,且相较于其他敷设方式,直埋敷设时绝缘层温差20℃限制对载流量的影响更小;双极海缆的载流量随双极间距增大而增加,流速为0.1 m/s时涡旋对海缆载流量有较小的提升作用;在绝缘层温差为6℃附近,电场发生翻转。研究结果可为敷设方式的选择以及载流量的预测和评估提供重要指导和参考。

Developing offshore wind power is an important measure to achieve the goal of′dual carbon′.DC submarine cables are important devices in offshore wind power transmission projects,and the research on the ampacity of submarine cables plays an important role in promoting the large-scale development of offshore wind power.In recent years,the research on the ampacity of high-voltage DC submarine cables has considered relatively single marine environmental factors,and the limitation of temperature difference of insulation layer has not fully be considered.The article establishes an electric-thermal-current coupling model of the 500 kV DC submarine cable and the seawater system.Under different laying methods for single and bipolar submarine cables,the effects of vertical ocean currents(currents flowing perpendicular to the length direction of the cable)flow velocity,limitation of temperature difference of insulation layer and the the different spacing of the bipolar cables on the ampacity are studied.The results show that considering the temperature difference limitation 20℃of the insulation layer comprehensively has a smaller ampacity compared with the situation only considering the temperature limitation 70℃of the wire core,and direct burial laying has a smaller impact on the ampacity compared to any other laying method.It is also found that the ampacity of bipolar submarine cables increases with the increase of the distance between the two poles.When the flow rate is 0.1 m/s,the vortex have a small improvement effect on the ampacity of the submarine cable.The electric field flips around a temperature difference of 6℃in the insulation layer.The research results can provide important guidance and reference for the selection of laying methods,and even for the prediction or evaluation of ampacity.