Security-constrained economic dispatch exploiting the operational flexibility of transmission networks

Abstract

Dynamic line rating (DLR) and flexible ac transmission system (FACTS) are two technologies to enhance the utilization of existing transmission lines and exploit the inherent transmission-side flexibility. This paper coordinates DLR and FACTS in a two-stage security-constrained economic dispatch (SCED) model to enhance the power system flexibility in N-K contingency management and reduce operational cost. To utilize DLR while handling its uncertainty, spatial–temporal joint chance constraints (JCCs) are used. A scalable reformulation method for these JCCs is developed, which enables considering the spatial–temporal correlations between DLRs and co-optimizing the DLR utilization with system dispatch. To leverage the flexibility of FACTS, the adjustments of FACTS set points before and after the occurrence of any N-K line outage are modelled. The proposed SCED model is reformulated as a triple-level robust model, which avoids enumerating all possible N-K outages in the SCED model and obtains a more reasonable model size. To handle the presence of binary variables in the lowest level of the robust model, a nested column-and-constraint generation solution structure is designed. Case studies on IEEE 14 and 118-bus systems are conducted to verify the effectiveness of the proposed SCED model.