方框带射线型接地体冲击特性影响因素  

Influence Factor of Impulse Characteristics of Box and Ray Grounding Device

作　　者：杨帅[1] 李超英 谭波[3] 邹建明[4] 刘华钢[4] 周文俊[1] 

机构地区：[1]武汉大学电气工程学院,武汉430072 [2]厦门供电公司,厦门361004 [3]中国电力科学研究院,武汉430074 [4]华中电网有限公司,武汉430077

出　　处：《高电压技术》2016年第5期1548-1555,共8页High Voltage Engineering

基　　金：国家自然科学基金(51277136)~~

摘　　要：为研究方框带射线型接地体冲击特性,从而获取有效降阻方法,采用模拟试验方法在单一土壤与双层土壤条件下,分别研究了土壤参数、电流波前时间以及形状尺寸对接地体冲击特性的影响。结果表明：相比于黏土,细沙的临界击穿场强更大,小幅值电流造成的火花效应并不显著,随着电流幅值增加,火花效应开始显现,冲击接地电阻下降趋势更加明显。冲击电流幅值由60 k A增至90 kA,细沙环境下H–60冲击接地电阻降幅为11.7%,黏土环境下H-60冲击接地电阻降幅为1.7%;根据试验结果,波前时间对接地体冲击特性影响不大,在波前时间范围4～20μs、幅值3.125 kA的冲击电流下,H-10接地体冲击接地电阻维持在6.5？左右;方框带射线型接地体结构尺寸中,射线存在有效利用长度,方框边长与射线比例在0.167～0.273之间较优。由于导体间的屏蔽作用,添加分支的降阻措施有一定的局限性。采用调整方框带射线型接地体结构尺寸的方式降阻时,需综合考虑泄流通道与屏蔽效应的影响。In order to obtain an effective method to reduce the impulse grounding resistance, impulse characteristics of box and ray grounding device need to be investigated. Based on the simulation experiment method, the influential factors such as soil types, current front time, and device shape, were studied under conditions of single-layer and double-layers soil. The results show that the critical breakdown strength of fine sand is larger compared with that of the clay. As the current amplitude is small, the spark effect is non-significant. With the increase of current amplitude, the spark effect begins to emerge and the impulse grounding resistance decreases rapidly. As the impulse current amplitude increases from 60 k A to 90 k A, the decreasing amplitude of H-60 impulse grounding resistance are 11.7% and 1.7%, respectively, in sandy soil and clay. According to the test results, the current front time does not affect the impulse characteristics of box and ray grounding device. In case of 3.125 kA current amplitude, the impulse grounding resistance maintains at 6.5 Ω as the current front time ranges from 4 μs to 20 μs. There is an effective length in the design of radiation length. The better ratio range between the side length and the ray length is from 0.167 to 0.273. Due to the shielding effect among the conductors of grounding device, adding the branch is not an efficient method to reduce the impulse grounding resistance. Discharging channel and shielding effect must be put into consideration comprehensively when structure size adjustment is applied in grounding resistance reduction.

关 键 词：接地体 冲击接地电阻 屏蔽效应 电感效应 火花效应 降阻 

分 类 号：TM862[电气工程—高电压与绝缘技术]