Prioritizing emergency control problems with fuzzy set theory

Power system emergencies are typically characterized by line overloads and/or voltage violations, Since human operators controlling these emergencies usually adopt a one-problem-at-a-time approach in correcting the violations, an emergency control algorithm designed to help the operator must also decide which problem should be pursued first. The discussion of the prioritization problem in current emergency control algorithms is incomplete-the criteria for selecting between voltage violations and overloads are simplistic, and most often based simply on the amount of violation. This paper analyzes how the fundamental difference in the nature of overloads and voltage violations problems makes prioritization difficult to resolve. Further, it shows how the problem falls naturally into the domain of fuzzy set theory, where overloads and voltage violations can be compared based on the same index. After discussions with utility operators/engineers, the prioritization algorithm is tested on a 1200-bus power system