高土壤电阻率地区柔性石墨复合接地材料与圆钢接地材料的有效长度对比研究

Comparative Study on the Effective Length between Flexible Graphite Composite Grounding Material and Round Steel Grounding Material in High Soil Resistivity

改善杆塔接地能够有效的降低输电线路雷击跳闸率,对于高土壤电阻率地区的杆塔,减小冲击接地电阻是降低雷击跳闸率的关键,而减小接地体冲击接地电阻可以通过延长接地体长度来实现,但是当长度超过一定值时,延长将不再有效。因此研究接地体的有效长度、选取有效长度更长的接地材料,对降低接地电阻有着重要意义。首先分析了接地体有效长度的物理意义,然后运用CDEGS仿真软件计算工程中常用的镀锌钢和柔性石墨复合材料水平接地体的工频接地电阻与接地体长度、冲击接地电阻与接地体长度之间的关系。由此对比在高土壤电阻率情况下柔性石墨复合接地材料的和镀锌钢材料的有效长度,并分析其原因。此后采用冲击散流试验加以验证,最后得出结论,高土壤电阻率情况并通以冲击电流时,柔性石墨复合材料接地体有更长的有效长度。

The improvement of grounding can effectively reduce the transmission line lightning trip rate, reducing the impact resistance is the key to reduce the lightning trip rate in high resistivity soil, and extending the length of the grounding material can reduce the value of grounding resistance. But when the length is long enough, the grounding resistance will not be reduced. So the study on the effective length and finding the material which has longer effective length are important to the reduce of the ground- ing resistance .In this paper, the author first study the effective length of the material by theoretical analy- sis, then uses the simulation software CDEGS to study the relationship between the power frequency grounding resistance and the length, and the relationship between the impulse grounding resistance and the length on the flexible graphite composite material and the galvanized steel. Then the effective length of the 2 materials has been contrasted and analyzed. An experiment about discharging current is carried out to verify the conclusion obtained above. And it is suggested that, under the impulse current, flexible graphite composite materials should be used in high resistivity soil, which has the longer effective length.