变电站周围管网及新建地网系统对原接地网特性参数的影响

Impacts of the Pipe Network around the Substation and the New Grounding System on the Characteristic Parameters of the Original Grounding Grid

“双碳”目标的大背景下,随着以高比例新能源为主体的新型电力系统的建设,原变电站接地网已然难以满足当下需求,存在着新改造地网与老旧地网的安全运行问题以及周围地下金属管网的接入使改造地网产生的参数变动问题。接地网的某项参数不达标,则会影响变电站和站内设备的稳定运行,对人身安全造成严重的影响。因此,需要分析改建地网及金属管网等原变电站周围管网系统参数指标的安全限值,综合考虑分层土壤结构、地下金属管网及其他周围地形对于改建地网安全运行的影响效应。基于矩量法并结合CDEGS接地网仿真软件搭建了新旧地网以及周边金属管道数学模型,综合考虑各种土壤特性下变电站周围金属管道以及新建地网对原变电站的各个特性参数,进行了分析研究,获得了多种情况下变电站接地网与金属管道以及原接地网与新建地网之间的阻性耦合影响曲线及各项接地参数的对比,并据此提出相应的防护措施。实验发现:对金属管道敷设绝缘层可以有效减小管道的散流作用,但对降低接触电压并不明显,敷设绝缘层前后接触电压仅下降3%;将新建地网与原接地网相连使原变电站接地网最大接触电压下降28.1%,降阻率达20%。为变电站接地网改造工程及新型电力系统的构建提供一定的理论依据。

In the context of the“Dual Carbon”goal,with the construction of a new power system dominated by a high proportion of new energy,the original substation grounding grid is no longer able to meet current needs.There exist issues with the safe operation of the new and old grounding grids,as well as the parameter changes caused by the connection of the surrounding underground metal pipeline network.If a certain parameter of the grounding grid does not meet the standard,it will affect the stable operation of the substation and equipment inside the station,and also have a serious impact on personal safety.Therefore,it is necessary to analyze the safety limits of the parameter indicators of the original substation’s surrounding pipeline system,such as the reconstructed grounding network and metal pipeline network,and comprehensively consider the impacts of layered soil structure,underground metal pipeline network,and other surrounding terrain on the safe operation of the reconstructed grounding network.Based on the method of moments and combined with the CDEGS grounding grid simulation software,this article builds a mathematical model of the new and old grounding grids and surrounding metal pipelines.Taking into account various soil characteristics,we have analyzed and studied metal pipelines around the substation and the newly built grounding grid for various characteristic parameters of the original substation,and obtained the resistance coupling influence curves and comparison of various grounding parameters between the substation grounding network and metal pipelines,as well as between the original grounding network and the newly built grounding network under various conditions,and proposed corresponding protective measures accordingly.The experiment in this article has found that laying an insulation layer on metal pipelines can effectively reduce the dissipation effect of the pipeline,but it is not significant in reducing the contact voltage.Before and after laying the insulation layer,the contact voltage only decreases by 3%;connecting the new grounding grid to the original grounding grid can reduce the maximum contact voltage of the original substation grounding grid by 28.1%,and the resistance reduction rate reaches 20%.The paper can provide a certain theoretical basis for the renovation project of the substation grounding network and the construction of new power systems.