华北某500kV变电站接地降阻优化研究

Study on Reducing Grounding Resistance of a 500kV Substation in North China

华北某500kV变电站地处平缓丘陵地区,土壤电阻率高,对变电站接地系统产生不利影响,必须进行降阻处理,使接地电阻、接触电位差、跨步电位差等各项指标满足安全要求。通过分析计算,提出在高土壤电阻率地区不必片面追求低的接地电阻值,在采取均压和防止高电位转移措施后,验算接触电位差和跨步电位差,可以适当提高接地电阻限值,并详细介绍斜接地极技术和爆破技术相结合的降阻措施在该变电站的应用及效果。

A 500 kV substation in north China is located in an area of gently rolling hills.The high soil resistivity in the area causes negative influence on the grounding system of the substation.To ensure that indices like the ground resistance,contact potential difference and step potential difference meet safety requirements,resistancereducing measures become necessary.According to the calculation and analysis,this paper shows that achieving a low ground resistance is not always needed in regions where soil resistivity is high.The threshold of ground resistance can be increased provided that the potential transfer is prevented,contact potential and step potential differences are examined and potential equalizing measures are adopted.The paper also introduces the combination use of slanting grounding electrode and blasting technique in details and its effects in the 500 kV substation.