双电压等级电网GIC的相互作用特征

Abstract

The mechanism of GIC (Geomagnetically Induced Current) is complex, which is influenced by a number of factors. In previous studies, when calculating GIC in a 500 kV power network, the 220 kV part of the network and voltage levels below are usually ignored. China launched the construction of 750 kV in 2005, and 1000 kV network in 2009. Such power networks consists of a large proportion of autotransformers, which enable direct electrical connection between the primary and secondary windings. Therefore, it is of great importance to study the GIC interaction between windings and the relative factors. We established GIC models according to the 750 and 330 kV power network as well as the 1000 kV and 500 kV network in Gansu province in China, using GIC Benchmark which is a standard testing case proposed in 2012. In our models, we adopted different scenarios where we chose to include or ignore the GIC from secondary windings. We calculated the GIC level in Gansu main network, 1000 kV and 500 kV networks under the geomagnetic storm in November 9 and 10, 2004. Comparative analysis was made between different scenarios to showcase the GIC interaction and its influence. Results revealed the characteristics of GIC interaction between two voltage levels, as well as GIC contribution from secondary windings in 750 and 1000 kV autotransformers, which will provide support to future researches in GIC calculation, risk evaluation of geomagnetic storms and GIC suppression in the power network.