Designing a Reliable Power System: Hydro-Quebec´s Integrated Approach

Hydro-Que´bec´s transmission system is among the most extensive and complex transmission networks in North America. The system´s design was improved over the last few years using an optimization process based on acquired experience as well as customers´ expectations. Hydro-Que´bec´s transmission system is currently designed in accordance with four major guiding principles based on a successive line of defense concept designed to counter events that are increasingly more severe but also increasingly more rare. These major guiding principles are a direct reflection of the level of risk that society accepts to tolerate in relation to the costs involved by higher reliability requirements. Que´bec´s specific context, which is characterized by long transmission lines, harsh weather, and customers´ heavy reliance on electricity for their heating needs, means that very high security standards must be used in the system design. To obtain a level of reliability on par with that of our neighbors´ systems, however, requires more stringent criteria and standards. This paper will describe the design philosophy of Hydro-Que´bec´s power system, the underlying major guiding principles, and the defense plans designed to ensure its reliability.