地磁感应电流行星际起因及其电网效应的初步分析

Primary Analysis on the Interplanetary Cause of Geomagnetically Induced Current and Its Effects on Power System

利用2004至2005年在广东岭澳监测到的地磁感应电流(Geomagneticily Induced Current,GIC)事件,分析了其对应的太阳驱动源和行星际太阳风结构,重点研究了GIC事件的行星际起因及效应,并利用小波变换对强GIC事件进行频谱分析.研究结果表明:(1)绝大多数GIC事件由全晕状日冕物质抛射(Coronal Mass Ejection,CME)主导驱动,其行星际起因则包含激波鞘层、磁云或多重行星际太阳风结构.(2)针对强GIC事件(2004-11-09)发现GIC事件强度前期的变化与磁云边界层相关,而后期的强度变化主要是磁云本身引起.(3)GIC在电力系统中相当于准直流,其能量体现在两个时间段,前期较弱属于脉冲类型,后期强度较大;关于GIC引起变压器温升的累积时间,相比GIC事件的前期,后期的累积时间更长,对电力系统以及设备的影响更为严重.(4)通过相关性分析,SYM-H指数和dBx/dt与GIC的相关性明显强于其它地磁指数与GIC的相关性.

In this paper, we use the measured data of geomagnetically induced current （GIC） in Ling＇ao nuclear power plant from 2004 to 2005 to analyze its solar driving source and interplanetary solar wind structure, focus on the interplanetary cause and its effects on power system, and apply the wavelet analysis to the greatest GIC event. We conclude that： （1） Most GIC events were driven by halo coronal mass ejections, and the sheath, the magnetic cloud, and the multiple interplanetary solar structure are the interplanetary cause of GIC events. （2） Based on the strongest event on 2004 November 9, we find that the fluctuation of GIC in the earlier stage was related to the magnetic cloud boundary layer, and the variation of GIC intensity in the later stage was caused by magnetic cloud itself. （3） Compared to the frequency of the power system （50 Hz）, the GIC can be equivalent to the quasi direct current. The energy of the GIC is embodied in the two time intervals within the wavelet power spectrum： the first interval is shown as the pulse type and with a weaker intensity, and the second one is stronger. Regarding to the cumulative time of the transformer temperature rise caused by GIC, the second interval has a longer duration than the first one. So during the second interval, it is more harmful to the power system and the equipments. （4） The correlations of SYM-H, and dBx/dt to GIC are significantly closer than those of other geomagnetic indices to GIC.