Synthesis of schedulers for planned shutdowns of power plants

We describe the synthesis of efficient schedulers for planned shutdowns of power plants for refueling and maintenance (outages), using an automated programming tool, KIDS. Currently, the utility industry has no automated tools to generate schedules that are both safe and resource-efficient. We focused on safety constraints since they are critical in this application. There are several aspects of this project that go beyond previous applications of KIDS to scheduling problems. First, scheduling of outages of power plants has a planning-like character since the scheduler needs to represent and maintain the complex state of the plant at all times considered during the scheduling process. Second, the particular safety constraints we considered required scheduling a pool of resources in the presence of time windows on each activity. To our knowledge the control and data structures that we developed for handling such a pool are novel. In terms of design knowledge, the outage scheduling problem is modeled as a constraint satisfaction problem and the synthesized algorithm is an instance of global search with constraint propagation. The derivation of specialized representations for the constraints to perform efficient propagation is a key aspect of our approach. In addition, finite differencing complements constraint propagation by efficiently maintaining the state of the world.