多次磁暴下特高压电网GIC统计规律研究

Statistical Analysis of Geomagnetically Induced Currents in UHV Power Grids Under Multiple Geomagnetic Storms

探明灾害性地磁感应电流(geomagnetically induced currents,GIC)在电网中的分布特征对于准确评估极端空间天气风险具有重要意义。该文依据Dst指数选取多次强磁暴数据,分别计算三华地区感应地电场和特高压(ultra-highvoltage,UHV)规划电网各变电站的GIC,再以这些计算值作为样本数据,通过各变电站GIC贡献率P、回归系数G以及概率分布参数a描述电网GIC的空间分布;参考可决系数R,得出地电场和GIC的概率分布模型,并据此预测各节点三相GIC的"百年一遇"值。结果表明,感应地电场符合对数正态分布,电网节点GIC符合韦伯分布;统计结果可反映电网遭受磁暴侵害的严重程度,为进一步评估电网GIC风险、制定合理的防治措施提供依据。

Ascertaining the distribution characteristics of disastrous geomagnetically induced currents(GIC) in a power grid is important to accurately evaluate the effects of extreme space weather on power grids. This paper presented the induced geoelectric fields in northern, center and eastern areas of China(Sanhua) and GIC at each substation in the ultra-high-voltage power grid during strong geomagnetic storms selected by the Dst index. The GIC contribution rate P for each substation, the regression coefficient G, and the parameter a of probability distribution were calculated to describe the spatial distribution of GIC in the power grid on the basis of sample data.The probability distribution model of geoelectric fields and GIC in the power grid were determined with reference to the R-squared value(R), and the 100-year GIC values of three-phases in each node were predicted accordingly. The results show that the logarithmic normal distribution and Weibull distribution are suitable probability distribution models for geoelectric field and GIC in the power grid respectively. The results reflect the severity of the damage of power grids by geomagnetic storms which can also provide the basis for controlling and evaluating the effects of GIC on a power grid.