Effective Controlled Islanding Method for Power Grids Solving a Sequence of Optimization Problems

Controlled islanding is an important approach to prevent instability in power grids. In this paper, a novel approach is proposed for power system separation, which consists of two steps: 1) Finding multiple islanding scenarios; 2) Choosing the best option to obtain the most desirable island. In the first step, different islanding solutions are determined by a proposed hierarchical clustering method. In this algorithm, which is based on a minimum active power flow disruption objective function, the generator coherency constraints are considered in the clustering process. In the second step, the best separation scenario is chosen based on an arbitrary objective function. Particularly, in this paper, the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available options. In so doing, the degree of load importance is also taken into account. The proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus grid. The simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria, which have not been addressed in the existing approaches. Moreover, the proposed method is computationally efficient and can be employed in real-scale power grids.