Real-time Curative Actions for Power Systems via Online Feedback Optimization

—Curative or remedial actions are the set of immedi- ate actions intended to bring the power grid to a safe operating point after a contingency. The proper functioning of these actions is essential to enable curative N − 1 security. Nowadays, curative actions are derived ahead of time, based on the anticipated future grid state. Due to the shift from steady to volatile energy resources, the grid state will frequently change and the curative actions would need to be pre-planned increasingly often. Instead of pre-planning, we propose to calculate curative actions in real- time after the occurrence of a contingency. Furthermore, with the shift from large bulk production to many small decentralized energy sources more devices need to be actuated to achieve the same outcome. This makes deriving curative actions more complex and therefore needs to be automated. Overall, this motivates us to derive curative actions in real-time using a method that is capable of the increasing complexity of the available curative actions. We show how the method of Online Feedback Optimization (OFO) can be used to derive curative actions in real-time in the form of a closed-loop controller. As a preliminary demonstration of these capabilities, we use an OFO controller that after a fault reduces the voltage difference over a breaker to enable the operators to reclose it. This test case is inspired by the 2003 Swiss-Italian blackout, which was caused by a relatively minor incident followed by ineffective curative actions. Finally, we identify and discuss some open questions that need to be addressed in order to use OFO to derive curative actions in real-time. Namely, these are timescale separation and robustness to model mismatch.