GIC observations and studies in the Hydro-Québec power system

Abstract

On March 13, 1989, at 7 h 45 UT, Hydro-Québec experienced a complete black-out of its system due to a severe geomagnetic storm. Consequently, service was interrupted for many hours and overvoltages resulting from line openings cost 6.5 M$ in material damages alone among a total of 13.2 M$. In 1991, geomagnetically induced currents (GIC) produced some effects and damages on the Radisson–Sandy Pond HVDC link. On March 24, at 21 h 55 UT, GIC larger than 110 A were measured in one of two transformers in parallel (presumably, giving a total of 220 A) at Radisson substation which led to the loss of the HVDC link. The same thing happened on October 28, but this time with material damages to equipment. From these events, short-term studies led to the upgrading of operational processes, modifications of opening thresholds of Static Var Compensators and modifications of some filters at Radisson. Also an agreement was concluded with Geological Survey of Canada (GSC) for sending a warning alert to the Network Control Centre (CCR) before any anticipated severe geomagnetic storms. Among more long-term studies, in collaboration with GSC, we have installed 5 acquisition substations along a 250-km long copper telephone line in Abitibi, a site typical of Hydro-Québec facilities, and from 1992 to 1994 measured ground voltages and magnetic fields every 10 s . The highest ground voltage measured at Louvicourt substation was ∼1.70 V/km for 20 s . Asymmetry measurement of line voltages, based on techniques developed at IREQ in the 1980s, have been upgraded, the number of installations has been increased (from 4 to 8) and functions like harmonic measurement have been added. Voltage asymmetries over a fixed threshold produce an alarm at the CCR, which reacts by taking security measures in network operation. During March 1989 and 1991 events, voltage asymmetry grew to 9.6% and 15.5%, respectively, at the Arnaud substation. A major change, for needs of network stability during short circuit or other contingencies, has been the installation of series compensation in 1996 into the Hydro-Québec 735-kV network. Since capacitors block DC current, the observed asymmetry has remained about 20% of that observed before. So, now, we are confident that our network would survive the anticipated worst case GIC.