基于分阶段产气的高压电缆阻水缓冲层状态评估

Evaluation Technology of Water-blocking Buffer Layer of High Voltage Cable Based on Stages Classification of Gases Evolution

阻水缓冲层烧蚀引起的高压电缆本体击穿事故,严重威胁了电力系统的稳定运行。现有研究主要集中在缓冲层失效致电缆击穿的机理,而对于高压电缆阻水缓冲层状态的评估方法鲜有报道。针对这一现状,论文将缓冲层的状态分为腐蚀阶段以及烧蚀阶段,研究了腐蚀阶段下缓冲层含水量、电压、表面压力对缓冲层析氢的影响,并使用气相色谱分析了腐蚀阶段以及烧蚀阶段中缓冲层产生的气体。最后,基于实验结果提出了腐蚀阶段的析氢产气机理、烧蚀阶段的缓冲层分解产气机理,以及通过缓冲层中H_(2)的体积分数及是否含有C_(2)H_(6)、C_(2)H_(4)和C_(2)H_(2)气体来评估缓冲层状态的方法,并在110 kV在运电缆中取气进行验证。析氢实验结果表明:腐蚀阶段下增大含水量、升高电压、增大压力会提高缓冲层的析氢速率,并且在一段时间后,氢气(H_(2))的体积分数将保持相对稳定。气相色谱实验结果表明,腐蚀阶段缓冲层产生的主要气体为H_(2)以及甲烷(CH_(4)),缓冲层在烧蚀阶段同样产生了H_(2),且相较于腐蚀阶段还额外产生了乙烷(C_(2)H_(6))、乙烯(C_(2)H_(4))以及乙炔(C_(2)H_(2))气体。验证结果表明,在运电缆中气体组分特点与实验室中薄片样本的实验结果相符合,证明了该评估方式具有可行性。研究结果可为高压电缆阻水缓冲层的状态评估提供参考。

High voltage(HV)cable breakdown accidents caused by ablation of water-blocking buffer layer occur frequently,which seriously threatens the stability of power system.The existing research mainly focuses on the breakdown accident mechanism caused by buffer layer failure,however,detailed investigations on the state evaluation method of water-blocking buffer layer on HV cable are rarely available.Therefore,this paper divides the state of buffer layer into corrosion stage and ablation stage.In this paper,the effects of water content,voltage and surface pressure of buffer layer on buffer hydrogen in corrosion stage were studied,and the gas produced by buffer layer in corrosion stage and ablation stage was analyzed by gas chromatography.Finally,based on the experimental results,this paper puts forward the hydrogen evolution and gas production mechanism in the corrosion stage and the decomposition and gas production mechanism of the buffer layer in the ablation stage,and puts forward a method to evaluate the state of the buffer layer according to the H_(2) concentration in the buffer layer and whether the buffer layer contains C_(2)H_(6),C_(2)H_(4) and C_(2)H_(2) gas.Moreover,the mechanism and the method are verified by taking gas from the 110 kV transmission cable.The results of hydrogen evolution experiment show that increasing the water content,voltage and pressure in the corrosion stage will increase the hydrogen evolution rate of the buffer layer,and the hydrogen(H_(2))concentration remains relatively stable after a period of time.The results of gas chromatography experiments show that the main gases produced by the buffer layer in the corrosion stage are H_(2) and methane(CH_(4)).The buffer layer also produces H_(2) in the ablation stage,and additionally produces ethane(C_(2)H_(6)),ethylene(C_(2)H_(4))and acetylene(C_(2)H_(2))gases compared with the corrosion stage.The verification results show that the characteristics of gas components in the in-service cable are consistent with the experimental results of sheet samples in the laboratory,which proves that the evaluation method is feasible.This paper provides a reference for the state evaluation of water-blocking buffer layer of HV cable.