Speaker
Description
Geomagnetic disturbances lead to the generation of geomagnetically induced currents (GICs) in technological systems like power grids. In some cases, mainly during intensive events, these GICs can irreversibly damage the transformers and even cause power grid blackouts.
At the same time, the proper numerical simulation of GICs is rather challenging task due to the many variables that affect the behaviour of GICs in the power grids. Examples are: a) both spatial and temporal behaviour of the inducing magnetic field varies for different events and regions; b) GICs are induced by geoelectric fields, that in turn, depends on the spatially and depth varying ground conductivity distribution; c) GICs are strongly dependent on power grid configuration. And, last but not least, in addition to the feasible models for the aforementioned variables one also needs effective numerical methods and computational codes that allows all of these issues to be taken into account.
In this presentation we show how these challenges were overcome or, at least, tackled by the New Zealand Solar Tsunamis project:
a) A new spatial source parametrisation was created by using the magnetic field data from both global INTERMAGNET network and New Zealand newly installed grid of magnetic field observations called MANA (Magnetometer Array for New Zealand Aotearoa). This model allows us to describe the behaviour of the inducing magnetic field above New Zealand with only 6 – 8 spatial modes;
b) Using the data collected during multiple magnetotelluric campaigns we created a new three-dimensional conductivity model for the whole of New Zealand;
c) A new power grid model was created by using the updated data provided by Transpower New Zealand Limited;
Using the multi-site transfer function approach we performed and validated the simulations of GICs during the strongest geomagnetic events in recent years, i.e., the "Gannon storm" of May 2024. The obtained results show the good or even near-perfect agreement with observed GICs and confirm that each and every aforementioned “ingredient” is necessary for the accurate simulation.
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