摘要
为解决发、变电站地线(包括架空避雷线和电缆外护套)对测试电流的分流严重影响接地阻抗测量准确性的技术难题,进行了基于模拟计算的分析。对220 kV变电站在接地阻抗测量时的地线分流情况进行了现场实测,结果与模拟计算结果一致,证明模拟计算方法可行。基于此计算模型,分析了影响地线分流效果的主要因素及其影响规律,指出地线分流可以达到50%甚至更高的水平。当发、变电站接地阻抗较大、沿线杆塔接地电阻较小、出线数量较多以及线路多为单回布置时,地线分流更严重,对接地阻抗测试结果影响更大。如果不考虑地线分流,接地阻抗测量结果会严重偏小。最后提出了提高接地阻抗准确度的方法:在地线不易断开的发、变电站中,采用计算接地阻抗测量时地线电流的分流情况,接地阻抗测量值应通过仿真计算来修正。
The shunt of test current from the ground wires, including overhead lightning conductors and outer sheath of cables, would seriously affect the accuracy of grounding impedance measurement. To solve this problem, we analyzed the shunt by simulative calculations. Firstly, we measured the current distribution in a grounding impedance measurement of a 220 kV substation. The results coincide with the simulative calculation, and this verifies the feasibility of the latter me- thod. After calculating, we analyzed the main factors and their influencing patterns of ground wire shunting. Ground wire shunting could highly reach as 50% or more, even got worse with greater grounding impedance of substation, smaller transmission tower impedance, great number of outlets, and dominating single-layout type of transmission lines, and eventually more seriously affected the tests of grounding resistance. If the ground diverting is not taken into consideration, grounding resistance measurement will have great negative deviance. At last we proposed a solution to improve the accu- racy of grounding impedance measurement： when it is easy to disconnect grounding wires, the grounding resistance measurement should be further corrected based on simulative calculations of ground current shunt.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2014年第3期707-713,共7页
High Voltage Engineering
基金
国家自然科学基金(51277107)~~
关键词
发电站
变电站
接地阻抗测量
架空地线
分流
接地网
power station
transformer substation
grounding impedance measurement
ground wire
shunt
groundinggrid
