Statistical approach for transient stability constrained optimal power flow

The transient stability constrained optimal power flow (TSC-OPF) is a big challenge in the field of power systems because of its high complexity and extensive computation effort involved in its solution. This study presents a new approach to compute the transient stability constraint formulated by the critical clearing time (CCT) in TSC-OPF. CCT has been determined by dual-kriging, a space interpolation method which has primarily been used in natural resources evaluation. Given the huge dimensionality of the problem, Pareto analysis is firstly used to reduce the number of input variables in an initial database to those which are significant to compute CCT. With the reduced variables, a new database has been constructed using a design of experiment to obtain a reduced number of observed points. As a result of this approach, the sets of dynamic and transient stability constraints to be considered in the optimisation process are reduced to one single stability constraint with only a few variables. Ultimately, the size of the resulting optimisation problem is almost similar to that of a conventional optimal power flow. The effectiveness of the proposed method is tested on the New England 10-machine 39-bus system and the larger 50-machine 145-bus power system.