Prevention of voltage collapse on the French power system

Protection against voltage collapse covers the whole decision-making process, from investment planning to real time operation. Specific tools and methodology have been used for many years on the French system to handle the problem of voltage security at the planning stage, and strict operating rules are enforced during operational planning and real time operation. The author discusses the whole decision process, from investment planning to real time operation, and the main measures designed to prevent voltage collapse. Then future trends and research for real time operation are examined