Modeling Geoelectric Fields and Geomagnetically Induced Currents Around New Zealand to Explore GIC in the South Island's Electrical Transmission Network
Modeling Geoelectric Fields and Geomagnetically Induced Currents Around New Zealand to Explore GIC in the South Island's Electrical Transmission Network
复制标题
DOI：
10.1002/2017sw001697
复制
发表时间：
2017-10
期刊：
影响因子：
--
通讯作者：
T. Divett;M. Ingham;C. Beggan;G. Richardson;C. Rodger;A. Thomson;M. Dalzell
中科院分区：
文献类型：
--
作者：
T. Divett;M. Ingham;C. Beggan;G. Richardson;C. Rodger;A. Thomson;M. Dalzell
新西兰南岛输电网络中的变压器在地磁风暴期间受到地磁感应电流(GIC)的影响。我们通过建立该地区的薄片电导(TSC)模型、地电场模型和GIC网络模型来探讨GIC对该网络的影响。(TSC由具有底层分层电阻率结构的薄片电导图组成。)使用在英国和爱尔兰成功使用的建模方法，我们应用了薄片模型来计算电场作为磁场和地面电导的函数。我们开发了一个基于大地电磁测量、地质学和水深测量的TSC模型，并对其进行了修改，以考虑近海沉积物。利用这种表示法，薄板模型与测量的阻抗矢量有很好的一致性。在空间均匀磁场变化的驱动下，薄片模型产生了以海陆边界为主的电场，受深海和陡峭地形的影响。无论磁场的方向如何，电场都有向西北-东南方向排列的强烈趋势。将该电场应用到GIC网络模型中，我们发现模拟的GIC是由西北-东南传输线主导的，而不是通常假设的东西向传输线主导的。
Transformers in New Zealand's South Island electrical transmission network have been impacted by geomagnetically induced currents (GIC) during geomagnetic storms. We explore the impact of GIC on this network by developing a thin‐sheet conductance (TSC) model for the region, a geoelectric field model, and a GIC network model. (The TSC is composed of a thin‐sheet conductance map with underlying layered resistivity structure.) Using modeling approaches that have been successfully used in the United Kingdom and Ireland, we applied a thin‐sheet model to calculate the electric field as a function of magnetic field and ground conductance. We developed a TSC model based on magnetotelluric surveys, geology, and bathymetry, modified to account for offshore sediments. Using this representation, the thin sheet model gave good agreement with measured impedance vectors. Driven by a spatially uniform magnetic field variation, the thin‐sheet model results in electric fields dominated by the ocean‐land boundary with effects due to the deep ocean and steep terrain. There is a strong tendency for the electric field to align northwest‐southeast, irrespective of the direction of the magnetic field. Applying this electric field to a GIC network model, we show that modeled GIC are dominated by northwest‐southeast transmission lines rather than east‐west lines usually assumed to dominate.