Advances in decision trees applied to power system security assessment

Originating from the general decision tree methodology, the “decision tree transient stability” method has been developing for about 7 years. Initially tailored to the conventional transient stability problem, this method has gradually evolved to handle many other power system security concerns: voltage security both preventive-wise and curative- (or emergency-) wise, transient stability power flow limits in large corridors, and steady-state security. All these applications have shown the suitability of the decision tree method for assessing power system security. At the same time, and despite some remaining limitations, they suggested that: (i) proper strategies have to be designed to solve existing, old problems in the conventional fields of planning, operation planning and real time operation; and (ii) proper strategies also have to be developed to tackle emergency problems which so far were considered to be beyond reach. This paper addresses the following two issues: appraise the present status of the decision tree security assessment (DTSA) method, i.e. what has been achieved so far and what still remains to be done; and suggest appropriate DTSA uses, i.e. (re)formulate old problems, identify new ones, and suggest appropriate strategies able to match them with the DTSA possibilities