Regional estimation of geomagnetically induced currents based on the local magnetic or electric field
Regional estimation of geomagnetically induced currents based on the local magnetic or electric field
复制标题
基于局部磁场或电场的地磁感应电流的区域估计
DOI：
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发表时间：
2015
期刊：
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通讯作者：
M. Wik
中科院分区：
文献类型：
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作者：
A. Viljanen;P. Wintoft;M. Wik
以往的研究已经证明了水平地磁场矢量的时间导数（dH /dt）和地磁感应电流（GIC）之间的密切关系在附近的位置在电网。类似地，GIC和局部水平地电场（E）之间存在高度相关性，通常根据测量的磁场建模。考虑到GIC预测，假设时间序列的详细预测是不可行的。相反，总结特定时期活动水平的其他措施更可取。在本文中，我们认为30分钟最大的dH /dt或E作为一个局部活动指标（|dH /dt| 30或|E| 30）。关于GIC，我们使用通过变电站中性线的电流总和，并将其30分钟最大值用作区域活动度量（GIC 30）。|dH /dt| 30在一个单一的点产生一个代理GIC活动在一个更大的区域。一个实际的结果是，如果|dH /dt| 30可以在某个点预测，那么也可以评估周围区域的预期GIC水平。正如还证明的那样，|E| 30和GIC 30线性依赖于|dH /dt| 30，因此与通常使用的活动指数相反，随着地磁活动的增加没有饱和。
Previous studies have demonstrated a close relationship between the time derivative of the horizontal geomagnetic field vector (dH /dt ) and geomagnetically induced currents (GIC) at a nearby location in a power grid. Similarly, a high correlation exists between GIC and the local horizontal geoelectric field (E ), typically modelled from a measured magnetic field.Considering GIC forecasting, it is not feasible to assume that detailed prediction of time series will be possible. Instead, other measures summarising the activity level over a given period are preferable. In this paper, we consider the 30-min maximum of dH /dt or E as a local activity indicator (|dH /dt |30 or |E |30 ). Concerning GIC, we use the sum of currents through the neutral leads at substations and apply its 30-min maximum as a regional activity measure (GIC30 ).We show that |dH /dt |30 at a single point yields a proxy for GIC activity in a larger region. A practical consequence is that if |dH /dt |30 can be predicted at some point then it is also possible to assess the expected GIC level in the surrounding area. As is also demonstrated, |E |30 and GIC30 depend linearly on |dH /dt |30 , so there is no saturation with increasing geomagnetic activity contrary to often used activity indices.