Long-Lasting Geomagnetically Induced Currents and Harmonic Distortion Observed in New Zealand During the 7-8 September 2017 Disturbed Period
Long-Lasting Geomagnetically Induced Currents and Harmonic Distortion Observed in New Zealand During the 7-8 September 2017 Disturbed Period
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DOI：
10.1029/2018sw001822
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发表时间：
2018-06-01
影响因子：
3.7
通讯作者：
Obana, Yuki
中科院分区：
文献类型：
--
作者：
Clilverd, Mark A.;Rodger, Craig J.;Obana, Yuki
2017年9月6日至9日，由于强烈的地磁风暴活动，在新西兰南岛达尼丁的中途布什变电站检测到几个周期的地磁感应电流(GIC)。分析了来自独特组合仪表的前所未有的数据覆盖范围，即变电站内单相组变压器T4上的GIC测量、附近磁场扰动测量、检测电力系统谐波存在的甚低频(VLF)宽带测量以及高压谐波失真测量。在25小时内发生了两次太阳风激波，产生了四个不同的GIC周期。其中两个GIC事件与冲击本身的到来有关。这些产生了巨大但短暂的GIC效应，导致没有可见的谐波产生。附近和更远的磁力计在测量这些全球范围的磁场扰动方面表现出很好的一致性。然而，当T4中的GIC水平连续超过15A时，随后的两个持续时间更长的GIC周期(持续时间长达30分钟)会产生VLF接收器系统检测到的谐波。附近和更远的磁力计在这些时刻对磁场扰动的测量结果有所不同，这表明靠近达尼丁的小尺度电离层电流结构的影响。VLF接收系统从变电站拾取谐波，最高可达30次谐波，与观察到的高压偶次谐波失真增加一致，奇次谐波失真略有下降。
Several periods of geomagnetically induced currents (GICs) were detected in the Halfway Bush substation in Dunedin, South Island, New Zealand, as a result of intense geomagnetic storm activity during 6 to 9 September 2017. Unprecedented data coverage from a unique combination of instrumentation is analyzed, that is, measurements of GIC on the single-phase bank transformer T4 located within the substation, nearby magnetic field perturbation measurements, very low frequency (VLF) wideband measurements detecting the presence of power system harmonics, and high-voltage harmonic distortion measurements. Two solar wind shocks occurred within 25 hr, generating four distinct periods of GIC. Two of the GIC events were associated with the arrival of the shocks themselves. These generated large but short-lived GIC effects that resulted in no observable harmonic generation. Nearby and more distant magnetometers showed good agreement in measuring these global-scale magnetic field perturbations. However, two subsequent longer-lasting GIC periods, up to 30 min in duration, generated harmonics detected by the VLF receiver systems, when GIC levels continuously exceeded 15 A in T4. Nearby and more distant magnetometers showed differences in their measurements of the magnetic field perturbations at these times, suggesting the influence of small-scale ionospheric current structures close to Dunedin. VLF receiver systems picked up harmonics from the substation, up to the 30th harmonic, consistent with observed high-voltage increases in even harmonic distortion, along with small decreases in odd harmonic distortion.