Upgrading HVAC circuit breakers using controlled switching: Hydro-Québec´s 20 year experience

Switching reactive components with a high voltage circuit breaker (CB) can generate transients on the electrical network that decrease power quality and produce excessive stresses on the power apparatus. While conventional solutions provide some degree of mitigation, a more effective and reliable solution has been successfully deployed and validated: Controlled Switching (CS). Furthermore, to extend the useful life of the existing CB and prevent its costly replacement, this solution has been retrofitted on more than 140 CBs over the last 20 years on the Hydro-Québec network. The technology has evolved considerably in the last ten years. Initially used for shunt reactors, then for shunt capacitor banks, this proven technology is now often applied to the energization of unloaded power transformers, as well. No matter the application type, CS retrofitting has proven to be effective on CBs from a variety of manufacturers and technologies. From this long experience, many lessons have been learned and innovative ideas developed regarding optimal target specifications, switching strategies, commissioning procedures and the valorization of data recorded during switching events. Using acquisition functionalities that are intrinsic to the Controlled Switching Device (CSD), it is now possible to go beyond theoretical principles and optimize the simulation models through analysis of field measurements. The ongoing process of data collection offers the possibility of expanding the knowledge in this field and improving the diagnostics of related equipment. It also allows the industrial partners to apply these developments to new applications such as Flexible AC Transmission Systems (FACTS), power line energization, fast switching and wind farm connection to the distribution network.