A 735 kV shunt reactors automatic switching system for Hydro-Quebec network

Hydro-Quebec has undertaken a major program to upgrade the reliability of its transmission system. Much effort has been directed toward increasing the system´s capacity to withstand extreme contingencies, usually caused by multiple incidents or the successive tripping of transmission lines. In order to counter such events, Hydro-Quebec has adopted a defensive scheme. Based entirely on automatic action, this scheme will mainly rely on: a 735 kV shunt reactor switching system (called MAIS); a generation rejection and/or remote load-shedding system (called RPTC); and an underfrequency load-shedding system. The MAIS system, which is the subject of this paper, will be implemented in 22 substations and is required to control voltage on the system after a severe event. Each MAIS system, acting locally, is entirely independent and will close or trip shunt reactors in response to local conditions