Enhancements to Stability Constrained OPF to Overcome Sub-optimality

Abstract

This article revisits the stability constrained optimal power flow (SOPF) model originally developed by the authors. One of the limitations of the SOPF model is that the representation of angular stability rests on assumptions that can lead to a sub-optimal dispatch outcome. The present research enhances the SOPF model to improve upon the quality of the solution. This article demonstrates that the feasible set of a stability-constrained optimal power flow problem can be open and hence the optimal solution may not exist. The article then reviews a step-by-step integration (SBSI) based approach which has the limitation of yielding sub-optimal solutions. A primary objective of the present research is to introduce two algorithms that can be used to find an improved solution, starting with a sub-optimal solution. Finally, the article also discusses several implementation issues including the concepts for dealing with multiple contingencies. Numerical examples are presented to illustrate the methodological aspects.