An application of a risk based methodology for defining security rules against voltage collapse

This paper presents how a risk based statistical approach has been carried out to assess voltage stability limits in the French Riviera subsystem and to construct new operating rules to avoid voltage collapse. The possibility of taking into account a large number of network situations as well as the uncertainties of the models enables us to assess accurately and robustly the stability limits of the system. The statistical methods allow one to find simple expressions of these limits and so to forecast when contingencies may lead with a high probability to a collapse. By including the criterion obtained in operating rules, Electricite de France has improved its knowledge of the stability limits and so, has been able to operate closer to these limits and to save a significant amount of money by re-dispatching the power plants in a cheaper way