Calculation of available transfer capability with transient stability constraints

In this paper, the available transfer capability (ATC) problem with the consideration of transient stability constraints is solved by using the direct nonlinear primal-dual interior point method. The integration of instability trajectory is used as a criterion for determining the degree of transient instability. The transient stability constraints are first converted into equivalents, and then incorporated into the optimal power flow equation set. The difficulties in computing the resultant Jacobian and Hessian matrices have been overcome. The proposed algorithm was fully validated on the WSCC 9-bus test system.