Effects of Geomagnetic Storm on UHV Power Grids in China

Along with the development of long-distance power transmission in China,it was discovered that high currents induced by geomagnetic storm,namely the geomagnetically induced current (GIC),appeared in Jiangsu and Guangdong provincial power grids as well as in other provincial power grids in China and the secure operation of power grids is possibly endangered by this phenomenon. Based on the analysis on GIC data monitored in power grids and the data of geomagnetism,the authors point out that except the strength of geomagnetic storm,the geoelectric structure of earth as well as the structure and parameters of power grid are also the important factors impacting GIC level. By means of physical model of geomagnetic storm and according to the features of UHV power grids such as low resistance of transmission lines,long distance of power transmission and adopting high-power single-phase transformer and so on,it is predicted that in UHV power grids the interferences caused by GIC will be more serious. According to the UHV power grid planning of China in 2010,an equivalent model of UHV power grid is built and by use of the data of ground electric field induced by typical geomagnetic storm the GIC levels of substations in East China and Guangdong province are preliminarily estimated respectively. Finally,the key problems to be solved in this research are summarized and in accordance with our own national conditions some relevant suggestions are put forward.