Diagnosing insulation intrinsic ageing is essential for preventing insulation failure of submarine cables, and in case of failure, helping in any decision about maintenance actions. In this study, a novel aged cable diagnosis approach based on high-voltage frequency domain spectroscopy (HV-FDS) with broader frequency width is proposed to analyse the high-field polarisation characteristics and conductivity behaviour of 500 kV submarine polymeric cables insulation, aiming to support the evaluation of overall insulation ageing. The measurement principle of HV-FDS and relaxation mechanism are stated, and then focus is on studying the extent of change of polarisation and conduction properties of submarine cables insulation as a function of ageing stress and time. Moreover, the high-field polarisation characteristics and conductivity behaviour are discussed in-depth based on the carrier transport and trap properties. Finally, the novel diagnostic indicator based on the high-field characteristics is extracted to quantify the thermal ageing state of submarine cables insulation. Results show that the high-field polarisation characteristics and conductivity behaviour seem to become sensitive diagnostic quantities if measured at reasonably high voltage, which are able to reveal mechanisms associated with thermo-oxidative ageing as that generated in the testing procedure considered in this paper. Sensitivity is considerably higher than that experienced in typical dielectric spectroscopy approaches.

中文翻译：

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热老化对海底聚合物电缆绝缘高场极化特性和导电行为的影响

诊断绝缘固有老化对于防止海底电缆的绝缘故障至关重要，并且在发生故障时有助于做出有关维护措施的任何决定。在这项研究中，提出了一种基于具有更宽频率宽度的高压频域光谱 (HV-FDS) 的新型老化电缆诊断方法，用于分析 500 kV 海底聚合物电缆绝缘的高场极化特性和电导率行为，旨在支持整体绝缘老化评估。阐述了HV-FDS的测量原理和弛豫机制，重点研究了海缆绝缘的极化和导电特性随老化应力和时间的变化程度。而且，基于载流子传输和陷阱特性，深入讨论了高场极化特性和导电行为。最后，提取了基于高场特性的新型诊断指标，用于量化海缆绝缘热老化状态。结果表明，如果在合理的高电压下测量，高场极化特性和电导率行为似乎会成为敏感的诊断量，这能够揭示与本文所考虑的测试过程中产生的热氧化老化相关的机制。灵敏度比典型的介电光谱方法中的灵敏度高得多。提取基于高场特性的新型诊断指标，量化海底电缆绝缘热老化状态。结果表明，如果在合理的高电压下测量，高场极化特性和电导率行为似乎会成为敏感的诊断量，这能够揭示与本文所考虑的测试过程中产生的热氧化老化相关的机制。灵敏度比典型的介电光谱方法中的灵敏度高得多。提取基于高场特性的新型诊断指标，量化海底电缆绝缘热老化状态。结果表明，如果在合理的高电压下测量，高场极化特性和电导率行为似乎会成为敏感的诊断量，这能够揭示与本文所考虑的测试过程中产生的热氧化老化相关的机制。灵敏度比典型的介电光谱方法中的灵敏度高得多。这能够揭示与热氧化老化相关的机制，如本文所考虑的测试程序中产生的那样。灵敏度比典型的介电光谱方法中的灵敏度高得多。这能够揭示与热氧化老化相关的机制，如本文所考虑的测试程序中产生的那样。灵敏度比典型的介电光谱方法中的灵敏度高得多。