基于介电响应法的矿用电缆绝缘性能评估方法研究

Study on evaluation method of insulation performance of mine cable based on dielectric response method

矿用高压电缆在实际使用中易受电、热、机械应力等多种因素的复合作用,加速绝缘老化,易导致电缆漏电、短路或放电等故障。目前,介电响应法被引入矿用电缆绝缘性能及老化状态的分析、评估和诊断中。针对基于介电响应法的电缆绝缘性能及老化状态评估问题,以常用的三元乙丙橡胶(EPDM)绝缘矿用移动软电缆为研究对象,总结了介电响应法中回复电压法、极化/去极化电流法和频域介电谱法的基本原理和典型特征量,对比了3种方法的优缺点。介绍了扩展Debye模型提取的老化因子、修正介电驰豫模型提取的弛豫特征量、介质损耗积分谱等基于介电响应模型的电缆绝缘性能评估特征量。从基于回复电压法和极化/去极化电流法的矿用电缆电痕腐蚀程度判别,以及基于极化/去极化电流法和等温松弛电流、基于介电驰豫模型、基于介质损耗积分值的EPDM绝缘多应力老化状态评估等方面,综述了介电响应法在矿用电缆绝缘性能评估中的应用研究。针对基于介电响应法的矿用电缆绝缘性能评估存在的在线监测技术无法适应煤矿工况、评估用数据不足、绝缘劣化程度与特征量关系未知等问题,提出应重点研究电缆绝缘状态感知、绝缘劣化程度与特征量关系构建这2项关键技术。

The high voltage cable used in mine is affected by many factors,such as electricity,heat and machinery stress.These factors accelerate insulation aging and easily lead to cable leakage,short circuit or discharge.At present,the dielectric response method is introduced into analysis,evaluation and diagnosis of insulation performance and aging state of mine cables.In view of problems of insulation performance and aging state evaluation of mine cables,the commonly used ethylene propylene diene monomer(EPDM)insulated mobile flexible cable for mining is taken as the research object.The basic principles and typical characteristics of recovery voltage method,polarization/depolarization current method and frequency-domain dielectric spectroscopy method in dielectric response method are summarized.The advantages and disadvantages of the three methods are compared.The characteristics of cable insulation performance evaluation based on the dielectric response model are introduced.The characteristics include the aging factor extracted by the extended Debye model,relaxation characteristics extracted by the modified dielectric relaxation model and dielectric loss integral spectrum.The application of the dielectric response method in the evaluation of the insulation performance of mine cables is summarized from the following aspects.The aspects include the identification of trace corrosion degree of mine cables based on recovery voltage method and polarization/depolarization current method.The aspects include the evaluation of EPDM insulation multi-stress aging state based on polarization/depolarization current method and isothermal relaxation current,based on dielectric relaxation model and based on dielectric loss integral value.The existing online monitoring technology for the evaluation of the insulation performance of mine cables based on the dielectric response method cannot adapt to the working conditions of coal mines.The evaluation data is insufficient,and the relationship between the insulation deterioration degree and the characteristic quantity is unknown.In order to solve the above problems,this paper puts forward that the research should focus on two key technologies,namely,cable insulation state perception and the relationship between insulation degradation degree and characteristic quantity construction.