高压直流电缆附件内缺陷对电场分布的影响研究

发布时间：2018-07-06 12:19

本文选题：高压直流电缆附件 + 硅橡胶　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：随着柔性直流输电技术和直流电缆制造技术的日渐成熟,交联聚乙烯绝缘高压直流电缆以其优异的性能在跨越海峡输电、穿越隧道送电和可再生能源发电等领域成为了直流塑料电缆的首选。在电缆线路中电缆附件扮演着衔接、过渡等重要角色,是电缆系统重要组成部分,同时也是输电线路的薄弱环节,故障多发部位。合理选择绝缘材料,全面研究电缆附件内含有典型缺陷情况下的电场分布规律,有助于掌握电缆线路运行状态,及时发现和修复故障隐患,提高电缆系统的供电可靠性,对高压直流电缆系统的长期稳定运行具有重要意义。本文首先根据高压直流电缆附件材料的基础性能采用多物理场耦合仿真软件(Comsol Multiphycics)构建出高压直流电缆附件仿真模型,根据电缆附件内电场分布仿真结果选择出一种电场分布特性优良的增强绝缘与电缆本体绝缘组合方案。其次,基于建立的高压直流电缆附件仿真模型,仿真研究不同电压幅值、不同温度梯度及过电压条件下电缆附件内含有典型缺陷时稳态和暂态电场分布规律。最后,探究缺陷位置与最大畸变电场位置的对应关系,并且评估各种缺陷对电缆附件的危害程度。仿真结果发现:在直流电压作用下,非线性硅橡胶具有较强均化电场分布的能力,使无缺陷的直流电缆附件内最大电场分布于电缆本体绝缘中,且外施电压幅值越高均化电场分布的能力越强;应力锥安装错位时,电场畸变程度随电缆外屏蔽超出应力锥根部距离增加而增大,超出距离过长会导致应力控制体丧失均化电场分布的作用;增强绝缘内有气泡时,电场主要集中在气泡附近,最大电场强度超过空气的击穿场强;应力锥表面存在微小凸起时,会使凸起附近局部电场明显增强;温度梯度较大时,电缆接头本体绝缘内出现场强分布翻转现象,且最大场强位置由高压屏蔽管端部转移到应力锥根部附近;电缆本体绝缘表面存在导电微粒时,整个电缆接头内的最大场强都位于导电微粒边缘。在直流叠加冲击电压作用下,无论叠加同极性还是反极性冲击电压,冲击过程中电缆附件内最大场强始终位于线芯附近的交联聚乙烯绝缘内,且叠加同极性冲击电压过程的最大场强高于叠加反极性冲击电压过程中最大场强。
[Abstract]:With the development of flexible DC transmission technology and DC cable manufacturing technology, XLPE insulated HVDC cable is transmitted across straits with its excellent performance. Power generation through tunnels and renewable energy has become the first choice of DC plastic cables. Cable accessories play an important role in the connection and transition of cable lines, which is an important part of cable system, and is also the weak link of transmission lines and the location of multiple faults. The reasonable selection of insulating materials and the comprehensive study of the electric field distribution law in the case of typical defects in the cable accessory are helpful to master the running state of the cable line, to discover and repair the hidden trouble in time, and to improve the power supply reliability of the cable system. It is of great significance for the long-term stable operation of HVDC cable system. In this paper, according to the basic properties of HVDC cable accessories, the simulation model of HVDC cable accessories is constructed by Comsol Multiphycics. According to the simulation results of electric field distribution in cable accessories, a combination scheme of enhanced insulation and cable body insulation with excellent electric field distribution characteristics is selected. Secondly, based on the simulation model of HVDC cable accessories, the distribution of steady and transient electric fields under different voltage amplitude, different temperature gradient and overvoltage is studied. Finally, the relationship between the defect location and the maximum distorted electric field position is explored, and the harm of various defects to cable accessories is evaluated. The simulation results show that the nonlinear silicone rubber has a strong ability to homogenize the electric field distribution under the action of DC voltage, so that the maximum electric field in the accessories of the non-defective DC cable is distributed in the insulation of the cable body. The higher the amplitude of applied voltage is, the stronger the ability of homogenizing electric field distribution is, and when the stress cone is mislocated, the degree of electric field distortion increases with the distance of the shield outside the cable beyond the root of the stress cone increasing. When there are bubbles in the reinforcement insulation, the electric field mainly concentrates near the bubble, the maximum electric field intensity exceeds the breakdown field intensity of the air, and when the surface of the stress cone is slightly raised, the electric field will lose the effect of homogenizing the distribution of the electric field when the distance is too long. When the temperature gradient is high, the distribution of field intensity flips in the insulation of the cable joint, and the position of the maximum field intensity is transferred from the end of the high voltage shield pipe to the root of the stress cone. When there are conductive particles on the insulation surface of the cable, the maximum field strength of the cable joint is located at the edge of the conductive particle. Under the action of DC superposition impulse voltage, the maximum field strength of cable accessory is always located in the cross-linked polyethylene insulation near the wire core during the shock process, regardless of the superposition of the same polarity or reverse polarity impulse voltage. The maximum field strength of the superposition of the same polarity impulse voltage is higher than that of the superposed reverse polarity impulse voltage.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM75

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