中文摘要：

相同感应地电场作用下,不同电压等级输电线路的地磁感应电流（geomagnetically induced currents,GIC）大小不同,以往的GIC计算集中在电网最高电压等级线路,通常忽略其他电压等级线路的GIC。交流特高压电网建设使我国电网增加了1 000 kV电压等级,综合考虑线路长度、单位阻值等GIC影响因素,准确计算包括500 kV超高压及1 000 kV特高压的多电压等级电网的GIC是重要研究课题。以我国多电压等级电网（三华电网）为例,分别考虑1 000 kV单电压等级网络（称电网1）和500、1 000 kV双电压等级网络（称电网2）,建立了电网1及电网2的全节点GIC模型并提出了多电压等级电网的GIC算法,计算了两种感应地电场情况下电网1及电网2的GIC,比较了两种情况下电网1及电网2的GIC计算结果。计算结果表明,500 kV超高压电网的GIC对1 000 kV特高压变电站的GIC水平有较大的影响,在多电压等级电网的GIC计算中,不能只计算最高电压等级电网的GIC,而忽略次级高压电网GIC的影响。

英文摘要：

Geomagnetically induced currents（GIC） with different amplitudes appear in transmission lines belonging to different voltage classes under the same environment of geomagnetically induced electric field. Former calculations of GIC mainly paid attention to the transmission lines with the highest voltage class and the GIC in transmission lines belonging to other voltage classes were usually neglected. Along with the construction of ultra high voltage（UHV） AC power grid, a new voltage class, namely the voltage class of 1 000 kV, was added into the voltage classes for transmission lines in China. It is an important research topic to accurately calculate the GIC of interconnected power grid containing multi voltage classes, including the 1 000 kV UHVAC and the 500 kV extra high voltage（EHV） AC, in which the compacting factors of GIC such as length and specific resistance of transmission line are synthetically considered. Taking China＇s interconnected power grid composed of North China power grid, Central China power grid and East China power grid as example, in which the power grid with single voltage class of 1 000 kV（for short Grid 1） and the grid containing two voltage classes of 1 000 kV and 500 kV（for short Grid 2） are separately considered, two full node GIC models for Grid 1 and Grid 2 are established and a GIC algorithm for power grid with multi voltage classes is put forward. The GIC of Grid 1 and Grid 2 under two kinds of geomagnetically induced electric fields are calculated respectively, and the obtained calculation results are compared. Calculation results show that the GIC in 500 kV EHVAC power grid greatly impacts the GIC level of 1 000 kV UHVAC substation; in the GIC calculation of power grid containing multi voltage classes it is not appropriate tocalculate the GIC in the power grid with the highest voltage class only while the impact from the GIC in the power grid belonging to the next highest voltage class is neglected.