Optimal re-dispatch of an isolated system considering transient stability constraints

In this paper, an algorithm for calculating the optimal operation of a system with different load states and fault clearing times is proposed. The algorithm simultaneously considers both economic and stability constraints. The proposed formulation is evaluated on the Majorca and Minorca islands power system, which is a small, isolated system with low inertia. A conventional optimisation tool is used to solve the optimisation problem. The results show the efficiency of the proposed approach and the advantages of including stability restrictions in the optimisation analysis. The application of the algorithm to different operation points is used to evaluate the cost of assuring the transient stability after a severe fault in the transmission grid. The analysis of different fault clearing times is used to estimate the economic savings of implementing a faster protection system.

► An optimisation problem representing economic and stability objectives is proposed.
► The problem is solved using an usual algorithm without numerical approximations.
► The optimisation algorithm is applied to a real small isolated system.
► The method evaluates the cost of assuring the transient stability of the system.
► Using the algorithm the economic effect of faster protections can be determined.