Undervoltage load shedding scheme for the Hydro-Quebec system

In recent years, Hydro-Quebec has undertaken a major program to upgrade the reliability of its transmission system. Much effort has been focused on increasing the system's ability to withstand extreme contingencies, usually caused by multiple incidents or the successive tripping of transmission lines. This work deals with the conception and the control logic of an undervoltage load shedding scheme aimed at protecting the Hydro-Quebec system against long-term voltage instability. Various results showing the impact of the operation of these automatisms on the system stability are provided in this paper.