Research on the Calculation Method of Geoelectric Field Environment Under Strong Geomagnetic Disturbance Events

Geomagnetic disturbance events could induce geomagnetically induced currents(GIC), which directly damages primary equipment such as transformers and circuit breakers, posing a threat to power grid security. Strong geomagnetic disturbances(GMD) can be generated by late-time high-altitude nuclear electromagnetic pulses(HEMP-E3) and solar storm caused geomagnetic storms(SS-GMD), both of which lead to widespread strong disturbances in the geomagnetic field. Considering the construction of China's new power system and its complex geological structure, calculating the induced ground electric field under strong geomagnetic disturbance events is crucial. In this paper, we first analyze the similarities and differences in typical electric field waveforms under HEMP E3 and GMD environments. The calculation methods and geodetic models required for simulating induced ground electric fields under strong geomagnetic disturbance conditions are mentioned. Next, we discuss the method to obtain magnetic field data during strong geomagnetic disturbance events. Finally, two induced geoelectric field calculation models based on one-dimensional layered geodetic conductivity model and three-dimensional geodetic model are established. We simulate the temporal changes and visualize the distribution of induced ground electric fields under strong geomagnetic disturbance environments, and investigate the impact of magnetic field data and geodetic conductivity structure on the amplitude and direction of induced ground electric fields. This work can provide a reference for subsequent calculations of ground electric fields under HEMP E3 and the assessment of GIC in large and complex power grids.