A methodology to solve the network expansion planning problem considering N-1 security criterion is proposed. The main idea to achieve the desired results is to separate the whole problem into two subproblems and solve them iteratively. The aim of upper level problem is to solve the mixed-integer programming model with all identified constraints. For the lower level problem, all N-1 contingencies are checked one by one and the corresponding constraints are added the upper level problem if line overload or network split is found. Each constraint is formed based on rigorous sensitivity or network topology analysis. The iteration between the two subproblems stops till a satisfactory planning solution is reached. Test results on two systems show effectiveness of the proposed method.
Hu, Z., & Li, F. (2010). Network expansion planning considering N-1 security criterion by iterative mixed-integer programming approach. In IEEE Power and Energy Society General Meeting 2010 New York: IEEE. https://doi.org/10.1109/PES.2010.5589271