文档介绍：摘要
发、变电站接地系统是保证设备与人身安全,维护电力系统可靠运行的重要措施。近年来,随着电力系统容量的急剧增大,入地短路电流大幅上升。许多变电站建于土壤状况复杂地区,如何根据实际的不均匀土壤,结合新的施工工艺,在面积有限、土壤电阻率较高地区设计出符合国家规程规定的接地系统是保障电力系统运行人员和设备安全的一项重要工作。
资料表明, 国内外近年来由于接地不良,造成事故扩大,导致系统停运、设备损坏的例子是不少的。与发、变电站接地系统有关的问题主要有5 个:接地系统的精确设计; 土壤分层结构分析;接地系统的腐蚀诊断; 高土壤电阻率地区接地系统的降阻和发、变电站接地电阻的准确测量。
发、变电站的接地装置一般都是以水平接地极为主,外缘闭合,内部敷设若干均压导体的接地网。在过去的设计中,均压导体一般按3m,5m,7m,10m等间距布置。由于端部和邻近效应,按等间距布置的地网地面电位分布很不均匀,地网边角处网孔接触电势远比中心网孔接触电势高,而且这种差值随着地网面积和网孔数的增加而加大。根据理论分析、计算和模拟试验结果表明,采用不等间距布置地网,既从地网边缘到中心,导体间距按一定的规律逐渐增加,就能使各网孔电势大致相等。这样既提高了安全水平,又可节省大量的刚才和施工费用。通过对具体变电站的均压导体不等间距布置的实际应用进行了研究,采用地网计算软件GPC的反复计算,得到了地网布置的最优化方案。使得接地电阻、接触电势比等间距布置时都有所降低,并且大幅减少了水平接地体的使用,节约了施工成本,具有一定的工程实用价值。
关键词:接地电阻,接触电势,跨步电势,不等间距导体
ABSTRACT
The ground systems in power plants and substations are the important measures to ensure the safe of equipment and human body and maintain reliable operation of power systems. With the rapid increase of the power system capability in recent years, groud fault current increase greatly. How to design standard substation grids in limited, non-uniform, high soil resistivity regions using suitable decreasing resistance method to keep the safe and reliable operation of the power system stuffs and device is crucial.
It is shown in information that the poor grounding has caused failures and resulted in expansion of failure , outage of system and equipment damage both domestically and abroad in recent years. There are 5 main issues related to the ground system in power plant and substations : precision design of ground system; analysis on soil layered structure ;diagnosis on corrosion of ground system; resistance reduction of ground system in areas with high soil resistivity and accurate measurement of ground resistance in power plants and substations.
Commonly ,the grouding system of a power plate or substation is a within equalizing voltage conductors .The conductor is arranged with space between 3m ,5m,7m,10m,which cause the surface voltage distributing unequal .The hole voltag