Studies Of Practical Algorithm Of ESP Based On The Complex Image Theory

Calculating Earth's surface potential (ESP) is the precondition to assess the geomagnetically induced currents (GIC) of the power grids caused by geomagnetic variations. Complex image theory (CIM) can be used for ESP's rapid calculation. The principle of auroral electrojet current source model required by CIM is derived in this paper based on the Maxwell equations, image theory of electromagnetic fields and characteristics of quasi-static fields. And the earth is modeled by a layered structure, in which horizontal layer, the conductivity is uniform. Combining with relevant research home and abroad, this paper developed ESP formula based on CIM. The model and the algorithm have been tested according to the measured GIC data of Yang-Huai high-voltage transmission system. In the end, with the use of infinite long line current model and the algorithm, northwest 750kV programming grid's ESP was given when magnetic storms like December 2006 occurred and the amplitudes of GIC flowed through transformers of the grids in 2008 and 2010 were given respectively.