输电线路的数字微地形自动提取方法

Automatic Extraction of Digital Micro Landform for Transmission Lines

微地形是输电线路工程安全运行、电线积冰风险区划和线路建设期能耗计算等工作的重要基础,实现输电线路微地形的合理提取是复杂地形条件下电网工程建设的前提与保证。针对传统输电线路微地形提取存在决策知识模糊、主观因素影响大和缺少定量提取指标等问题,依据规程中微地形分类体系,提出了以地形位置指数、坡度、相对高程和水体距离为特征因子的组合表达输电线路微地形提取决策方案,利用数字地形分析技术建立了输电线路微地形自动提取方法。以2012—2018年某电网公司9条输电线路域栅格数字高程模型数据进行提取实验,实验结果与分析表明,所提方法能够有效提取垭口地形、高山地形、抬升地形、峡谷地形和水汽地形5类典型输电线路微地形,且揭示了微地形分布与线路灾害发生的相关性,可为电网建设可行性论证、线路精细化设计等提供技术支持。

Objects:Micro landform is an important basis for safe operation of transmission lines engi⁃neering,the risk division of lines icing and the calculation of energy consumption during the construction pe⁃riod of transmission lines.As the national grid extends and voltage levels increases,there are a lot of trans⁃mission lines passing through the micro landform area and damaged seriously.The traditional macro geo⁃morphologic map can not show the micro landform characteristics accurately.It is subjective and costly for identifying micro landform by experts on the spot base on aerial photography and satellite images.Further⁃more,it is difficult to meet actual engineering requirements.The automatic extraction micro landform of transmission lines is not only a requirement for digital transmission lines landform analysis precisely,but al⁃so a prerequisite and guarantee for the construction of power grid projects under complex landform condi⁃tions.Methods:According to the classification system of micro landform in the specifications,the micro landform types of transmission lines were investigated and five micro landform types including yakou,mountain,uplift,canyon and vapor were proposed.The micro landform type with yakou,mountain,up⁃lift,canyon focuses on regional terrain complexity and relief,as while vapour landform focuses on the causes of the disaster.A decision-making scheme was proposed by terrain position index,slope,relative elevation and water distance,and a method of transmission line micro landform extraction based on grid digital elevation model(DEM)was constructed.About the vapor landform,the water distribution data were applied to the experimental area,the water area units were divided,and water body distance was calculated by grid statistics.Results:9 transmission lines DEM data of a power grid company during 2012—2018 were used for extraction experiment.The micro landform type of yakou,mountain,uplift,canyon and vapor was extracted effectively,the position and tendency of the micro landform could be discriminated by the ex⁃traction results,and the statistical parameters of each transmission lines micro landform in the experimental area were obtained.A comparative analysis of disaster data form the influence of micro landform was added.It was found that the proportion of typical micro landform area where the disaster occurred was over 90%,much higher than the proportion of micro landform in the non-disaster area.Conclusions:The topo⁃graphic position index,slope,relative elevation and water body distance were adopted to describe the five typical micro landform characteristics of the transmission line with digital terrain analysis technology and the existing transmission line micro landform classification system.Mined the micro landform information,a micro landform extraction method of grid DEM for transmission line was established.Compared with the traditional manual sketching method,it is simple and efficient,and the boundary contour of the extraction results was obvious,which could provide basic support for transmission line construction.