GIC calculation in power grid based on layered earth mode

Geomagnetically induced currents (GIC) in power grid are highly depended on the magnetic storm intensity, the earth electrical structure, the network configuration and many other factors. The difference in the conductivity of ground at different depths is significant to calculate GIC accurately. According to the mechanism of GIC production, in this paper, it is firstly established the layered earth model, derived iterative formula of the earth wave impedance and the relationships between the earth surface potential (ESP) and the varying electromagnetic field, presented the ESP algorithm based on the plane wave model. Secondly, based on quasi-dc characteristic of GIC, equivalent models of components in power grids are set up, power grid modeling and its simplification method are brought forward, which take the direction of the transmission line, the electrical network structure, the run way and other influencing factors into consideration, and the matrix equation solution in convenience of calculation is deduced. Finally, based on the above work, the software has been developed to calculate ESP and power grid GIC. Taking Yanghuai power grid for example, the ESP and GIC in Yanghuai transmission system are calculated based on the geomagnetic data and the Yanghuai tectonic structure. The result compared with the measured data indicates that the proposed model and algorithm are simple, effective and of high accuracy.