Modelling considerations for the Hydro One real-time GMD management system

Hydro One (Ontario, Canada) has implemented a Geomagnetic Disturbances (GMD) management system in its control centre that combines real-time tracking of GMD events as well as an assessment of Geomagnetically Induced Currents (GIC) on every circuit and transformer in the 230 kV and 500 kV networks from magnetic field measurements. Transformer reactive power loss and hot spot heating due to half-cycle saturation of every transformer with a grounded winding above 230 kV is also estimated. The computational demands in real time required modeling techniques not usually associated with GIC simulations in large networks. This paper describes the modeling approach, capabilities, and usage to make real-time operational decisions during a GMD event.