单芯海缆两端环流不匹配问题及评价方法研究

Mismatched Circulation Conditions and Evaluation of Single-core Submarine Cables

海缆是海上风电系统重要构成部分,接地环流是制约海缆设计及运行状态的关键要素。实际运行经验表明部分海上风场的单芯海缆存在陆上段和海上段接地环流严重不匹配现象,但是造成这种不匹配工况的原因不明,更无法根据这一现象对海缆运行状态进行清晰判断。该文依据现场海缆实际结构建立其分布参数模型,针对铠装接地和铠装金属护套全线接地两种接地方式对海缆接地环流进行分析,指出铠装全线接地时出现不匹配接地环流的原因为铠装和金属护套之间存在短路电阻;而铠装和金属护套全线接地情况下,出现不匹配接地环流的原因为铠装和金属护套之间存在短路电阻或者海缆两端接地电阻不匹配。在此基础上,提出基于环流的海缆运行情况评价方法,为实际海缆运行状态的判断提供参考依据。

The submarine cable is an important component of offshore wind power system and the grounding circulation is a key factor to restrict the designing and operating of the submarine cable.Practical operating experiences show that there is a serious imbalance of the grounding currents in the onshore and offshore sections in the offshore wind field,but the cause of this mismatching is unknown,let alone a clear judgment on the operating state of the offshore cables with this phenomenon.In this paper,based on the actual structure of the submarine cable,we establish a distribution parameter model.For both the armor grounding and the armor/sheath grounding,the submarine cable grounding circulating currents are analyzed.The reason for the extremely mismatching grounding circulating current of the armor grounding cable is the existence of a short circuit resistance between the armor and the sheath of the offshore section;the reason for the extremely mismatching grounding circulating current of the armor/sheath grounding cable is the existence of a short circuit resistance between the armor and sheath or mismatched grounding resistance at both the ends of the cable.On this basis,an evaluation system of the submarine cable operating condition based on the circulation is proposed,which may provide a reference for the judgment of the actual submarine cable operating condition.