污秽环境下导线表面状态的变化机理与应用研究

The surface conditions of the conductors have great influence on corona discharge and its produced audible noise, radio interference, resultant electric field and ion flow electrification in the extra and ultra high voltage transmission lines. The structure, installing methods, life of the conductors is subjected to the electromagnetic environmental parameters for the high voltage transmission lines in contaminated areas. The composite effect of contamination, power polarity, electric field and air conditions on the variation of the conductors’ surface conditions has been seldom investigated before. An artificial climatic laboratory will be built in this research, the air condition, the component, density and granularity of the contamination can be controlled in the laboratory. A small corona cage will also be designed and built in the laboratory in order to carry out the research. Under the contaminated conditions, the effect of electric field, corona discharge, air conditions on the characteristics of the contamination on the surface of the conductors (the polarity of the applied voltage will be positive dc, negative dc and ac) will be invsetigated through theoretical and experimental research, therefore, the mechanism of the variation of conductor surface conditions under contaminated environment will be obtained. The scientific characterization and quantification of the conductor surface conditions will be brought out in this research. Based on the mechanism of the variation of conductor surface conditions under contaminated environment, the anti-contamination materials will be coated on the surface of the conductors, and the characteristics of the contamination on the surface of the conductors may be explored. Furthermore, the effective methods of reducing the contamination on the surface of the conductors under contaminated environment may be proposed.

超、特高压交直流输电线路中，导线的表面状态对其电晕放电特性及由电晕放电引起的可听噪声、无线电干扰、地面合成电场、离子电流等参数具有重要影响。对于在污秽地区长期运行的输电线路，其导线选型、安装方式、运行寿命等因素也受到电磁环境参数的制约。目前，鲜见综合考虑污秽物、电压极性、电场强度、大气条件等因素对导线表面状态变化规律的影响研究。本课题计划设计大气条件，污秽物成分、浓度、颗粒度可控的人工气候实验室及放置在其中的小型电晕笼，灵活开展多种因素对导线表面状态的影响试验。本项目将通过试验和理论计算，研究污秽条件下，电场强度、电晕放电、大气条件等多因素对正直流、负直流、交流导线表面积污特性的影响机理，提出导线表面状态的科学表征及量化方法。基于多种因素对导线表面状态的影响机理，本项目将初步探索导线表面覆涂防污材料后的积污规律；进而提出污秽条件下，减少导线表面积污的有效措施。

超、特高压交直流输电线路中，导线的表面状态对电磁环境参数具有重要影响。本课题主要研究了如下内容：.1.设计了电场、污秽物成分、浓度、积污时间可控的人工加速积污系统，开展了多种因素对交、直流导线表面状态影响的实验。在标称电场作用下，通过分析颗粒物的极化特性以及多颗粒物之间的相互作用，建立了颗粒物在直流导线表面积聚的数学物理模型，揭示了颗粒物在导线表面呈现近似链式分布的特点以及众多颗粒物在导线表面单点上逐渐堆积成“锥形”的自然规律。在离子流场作用下，通过分析离子流场中颗粒物的荷电特性，建立了颗粒物的运动模型，获得了不同电晕放电强度下的直流导线表面积污形貌，揭示了电晕放电在一定程度上会抑制直流导线表面积污的自然规律。.2.通过交流电压作用下对导线积污的理论及实验研究，发下了导线表面颗粒之间的积聚与发热的现象；基于颗粒极化后产生的电场，进行两个颗粒相互之间偶极力的分析，揭示了颗粒间积聚现象产生的机理；基于颗粒极化发热的模型，揭示了堆积颗粒之间将产生热效应的自然规律。.3. 结合SEM与图像处理的灰度矩阵两种工具，建立了分析导线表面状态的定量化手段。提出了一种快速可控的导线表面积聚颗粒物的方法，通过控制带电细丝，对被积污导线周围电场强度进行控制，实现颗粒物快速积聚且均匀性可控的目标，并基于此方法进行了颗粒物积聚在导线表面后的电晕效应实验。.4. 研究了空中颗粒物在导线表面的积污特性，对比了不同条件下的积污形貌。对于不均匀涂污导线，电晕放电增强、起晕电压降低、合成电场强度增大、在空间中不对称；均匀的积污使空气电离层的起始从导线表面外扩到绝缘层外表面，导致导线表面标称场强降低，抑制了电晕放电。.5.采用涂料固载法在光滑导线表面制备相应的TiO2光自洁薄膜导线，开展了光自洁薄膜导线的积污实验。在紫外光照射下，导线表面TiO2光自洁薄膜在一定程度上改善了导线表面的亲水性，同时有利于分解有机物，提高导线的起晕电压。