Equivalent circuits for modelling geomagnetically induced currents from a neighbouring network

Abstract

Geomagnetically induced currents (GIC) can pose a problem for power system operation. To assess the geomagnetic threat requires modelling of the GIC in the power system. However, as well as the characteristics of the system itself, GIC are affected by connections to neighbouring systems. This paper considers three choices of equivalent circuit for a neighbouring system. Model calculations are made for the Ontario system with equivalent circuits for the neighbouring Manitoba system, and vice versa. Values from these calculations are compared with the exact values determined from model calculations for the combined Ontario and Manitoba systems. The calculations with equivalent circuits produce errors in the GIC at substations that diminish with increasing distance of the substation from the connection to the neighbour. Comparison of the results showed that the best choice for an equivalent circuit comprises the induced voltage and resistance for the first transmission line into the neighbouring system.