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Modified GIC Estimation Using 3‐D Earth Conductivity
Space Weather ( IF 4.288 ) Pub Date : 2020-08-24 , DOI: 10.1029/2020sw002467
Anna Kelbert 1 , Greg M. Lucas 2
Affiliation  

Geomagnetically induced currents (GICs) are quasi‐direct current (DC) electric currents that flow in technological conductors during geomagnetic storms. Extreme GICs are hazardous to man‐made infrastructure. GICs enter and exit the technological systems, such as the electric power grid, at grounding points, and their magnitudes depend on the currents that flow underground. They are, therefore, a function of the Earth's electrical conductivity, represented at ground level as Earth impedances, as well as the resistance parameters of the power network. Traditional GIC estimation practices are based on Earth impedances obtained from laterally homogeneous or piecewise layered‐Earth models. We refer to these methods, collectively, as the 1‐D approximation. However, GIC hazard mitigation can be improved with more accurate GIC modeling that takes the spatially heterogeneous Earth's conductivity into account. Here, we propose a modified approximation for GIC estimation that is very similar to the 1‐D approximation but is instead derived from empirical 3‐D Earth impedances. Our formulation sets up the computation of static, frequency‐dependent power line telluric response functions, which, once computed, may be considered part of the power grid system model. These response functions may then be used for historical scenario analysis of GIC hazards and for simplified real‐time, albeit approximate, GIC estimation in a power grid. This modest modification to the simpler local field formulation approach avoids real‐time integration of geoelectric fields along power lines while taking the realistic 3‐D Earth into account in a rigorous manner. Once implemented, the method provides a power grid operator with the benefits of convenience and computational speed for a first look real‐time operational GIC hazard assessment. We estimate that the proposed modified 3‐D GIC modeling approach produces GIC values that are well within 50% of those obtained with the full‐scale power line integration of spatially variable geoelectric fields, for storms comparable in scale to the 2003 Halloween storm, all geological structures, and power lines located in the contiguous United States and other low‐ to middle‐latitude regions.

中文翻译:

使用3-D地球电导率的修正GIC估算

地磁感应电流(GIC)是在地磁风暴期间在技术导体中流动的准直流(DC)电流。极端GIC对人造基础设施有害。GIC在接地点进入和退出技术系统,例如电网,其大小取决于在地下流动的电流。因此,它们是地球电导率的函数,在地平面上表示为地球阻抗,以及电网的电阻参数。传统的GIC估算方法基于从横向均匀或分段分层地球模型获得的地球阻抗。我们将这些方法统称为一维近似。然而,可以通过更精确的GIC建模来改善GIC危害缓解,该模型考虑了空间异质地球的电导率。在这里,我们为GIC估算提出了一种修正的近似值,该近似值与一维近似值非常相似,但它是从经验3维地球阻抗得出的。我们的公式设置了静态的,依赖于频率的电力线碲响应函数的计算,一旦计算,就可以将其视为电网系统模型的一部分。然后,这些响应函数可用于GIC危害的历史情景分析,并用于简化电网中的实时GIC估算(尽管是近似值)。对较简单的局部场公式化方法的这种适度修改避免了沿电力线实时整合地电场,同时严格考虑了逼真的3D地球。一旦实施,该方法将为电网运营商带来方便和计算速度的优势,以便进行实时实时GIC危害评估。我们估计,对于与2003年万圣节风暴规模相当的风暴,拟议的经修改的3D GIC建模方法所产生的GIC值完全在空间可变地电场的全尺寸电力线集成所获得的GIC值的50%之内。地质结构,以及位于美国和其他中低纬度地区的电力线。该方法为电网运营商带来了方便和计算速度的优势,可以进行实时实时GIC危害评估。我们估计,对于与2003年万圣节风暴规模相当的风暴,拟议的经修改的3D GIC建模方法所产生的GIC值完全在空间可变地电场的全尺寸电力线集成所获得的GIC值的50%之内。地质结构以及位于美国和其他中低纬度地区的电力线。该方法为电网运营商带来了方便和计算速度的优势,可以进行实时实时GIC危害评估。我们估计,对于与2003年万圣节风暴规模相当的风暴,拟议的经修改的3D GIC建模方法所产生的GIC值完全在空间可变地电场的全尺寸电力线集成所获得的GIC值的50%之内。地质结构,以及位于美国和其他中低纬度地区的电力线。
更新日期:2020-08-24
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