高土壤电阻率地区变电站接地网设计思路

针对高土壤电阻率地区变电站接地系统的接地电阻很难满足规程要求的问题,根据设备安全与人身安全的要求,分析了接地网设计的约束条件,并结合工程实例讨论了常规的接地网设计方法在高土壤电阻率地区的局限性;提出了一种不拘泥于现有规程中接地电阻限值的设计思路,即结合变电站的运行参数与设备参数得到接地电阻允许值的上限并利用均衡电压的思想优化接地网结构,然后根据接触电压与跨步电压的要求校核、修改设计方案以保证人身安全,同时,适度增加对一、二次设备保护的投入,保证设备安全。在高土壤电阻率地区,将放宽接地电阻上限值与加强设备保护的思想结合,可降低工程总体造价,达到技术经济综合优化。实践证明,这种思路行之有效。

Grounding System Design Method in High Soil Resistivity Regions

This paper analyzes the restriction of grounding system design based on the requirements of equipment safety and personal safety,and discusses the limitation of conventional design methods in high soil resistivity regions with a real engineering project.Thereafter,a design method that is not restricted by the grounding resistance limit of the existing regulation is proposed.The main principle of this method is to increase the allowed value of grounding resistance and strengthen the equipment protection.The maximal allowed value of substation grounding resistance is calculated according to the working parameters and equipment parameters,and the initial design scheme is verified and modified according to the requirements of step voltage and touch voltage to ensure personal safety.The grounding system structure is optimized on the principle of balancing-voltage,and the unequal spacing grounding grid technology and the explosion grounding technology are very effective.Meanwhile,the expenses on equipment protection should be increased to guarantee safe running.If the increased expenses on equipment protection are lower than the cost of decreasing grounding resistance,the whole project cost would be reduced and the grounding system can be designed both safely and economically.This method has been proved to be effective in engineering practice.