Applying Exact MILP Formulation for Controlled Islanding of Power Systems

Power systems are prone to cascading outages leading to large-scale blackouts. Intentional controlled islanding (ICI) is an effective corrective control action that limits the consequences of these catastrophic events by splitting the system into smaller sustainable islands. This paper proposes an ICI algorithm based on an exact Mixed Integer Linear Programming Formulation (MILP) that directly determines an islanding solution with minimal power-flow disruption for any given number of islands, while ensuring that each island contains only coherent generators. In addition, the proposed algorithm enables operators to constrain any transmission line to be excluded from the solution, allows the control of the size of islands and ensures their connectivity. To reduce the search space of the MILP and the overall complexity of the problem, a preprocessing procedure that finds the trees which connect the generators of each coherent group with the minimum number of nodes is also presented. The exact ICI algorithm is tested using dynamic models of the IEEE 39- and IEEE 118-Bus test systems. Multiple case studies are developed to demonstrate the effectiveness of the algorithm to different system conditions.