Curative N-1 security restoration of transmission systems

Abstract

Congestion management is a key task of grid operators to ensure N-1-secure operation through remedial actions such as redispatch. Curative remedial actions, applied after the occurrence of a contingency, can increase the base loading of grid assets and thereby reduce the need for preventive remedial actions. The selection of suitable remedial actions is typically supported by numerical optimization models that aim to minimize congestion management costs. This work presents a preventive-curative-restorative congestion management strategy that incorporates the restoration of N-1 security into optimization programs used in operational planning. The resulting grid state is curatively N-1-1-secure. The model is based on a graph-based approach that enables an intuitive coupling of multiple preventive and curative grid states within a mixed-integer linear program. To reduce computational complexity, methods were developed to decrease the number of grid states that must be considered. Particular emphasis is placed on the integrated representation of the thermal reserves of overhead line conductors across two consecutive curative time windows within the optimization model.