用于青藏铁路格拉段接地系统的新型装置

青藏铁路格拉段经过大片高土壤电阻率的多年冻土地区,给变电站及输电线路杆塔等电力系统接地设计施工带来了前所未有的挑战。为了更好的降低接地电阻,笔者提出了适合该地区使用的新型接地装置———降阻模块。该模块具有较小的自身电阻,通过与土壤良好接触、增加等效半径等方式降低了接触电阻与散流电阻。为了进一步提高其降阻能力,在格拉段可采用换土等措施。根据铁路沿线接地网情况,给出了不同情况下接地模块接地电阻的计算公式,并分析了降阻模块个数变化对接地网利用系数的影响和利用系数的变化规律。通过模拟及现场实验表明,该降阻模块具有施工方便,散流特性好,降阻能力强等特点,为青藏铁路格拉段接地装置的选用提供了新的选择。

A New Grounding Device for Grounding Systems in the Ge-La Section of the Qinghai-Tibet Railway

The Qinghai-Tibet Railway Ge-La Section passes through the large-area permafrost of the Qinghai-Tibet Plateau which is featured by high soil resistivities.This unprecedentedly challenges design and construction of the power supply grounding system at substations and along transmission lines.A new grounding device(the resistance-reducing module) is introduced to reduce the grounding resistances and adapt to the local environment.The device has low self-resistance and contact and dispersed resistances reduced by improving soil contact and enlarging equivalent radii.The assistant method of changing the soil around the grounding device is adopted to better the resistance lowering capability.The formula for calculating the module grounding resistance is given.The influence of the changing number of the resistance-reducing modules on the utilization coefficients of the grounding system and also the changing rule of the utilization coefficients are analyzed.Simulation and site tests show that the new device has better dispersing feature and stronger resistance-reducing capability and is convenient in construction.So it is a new option for the grounding devices to be used along the Qinghai-Tibet Railway.