A Gravity Scale for Detecting and Analyzing Events Affecting Power System Reliability

Power system reliability is at the core of the responsibilities entrusted to RTE, the French Transmission System Operator. To detect events that provide information for system reliability, RTE uses preset criteria, grouped in a "Classification Scale of Significant System Events (ESS)". These events are positioned on a scale consisting of seven levels. The document first presents the principles governing the classification of ESS. It then explains the changes that took place up to 2004, the year the scale was greatly revised, in particular to take better account of the impact of the power system\´s new players resulting from institutional developments in Europe. The classification scale ranking criteria are presented, as well as the analyses and processing carried out using the ESS as a basis. Finally, examples of ESS contribution to feedback and reliability audits are given