Preventive transient stability control using constrained optimal power flow

A new methodology for obtaining the optimal power flow with transient stability constraints is proposed in this paper. The main algorithm decomposes the problem into conventional optimal power flow and optimal control sub-problems, which are solved independently. In the process of optimal control, the transient stability index expressed by semi-infinite dimension constraints is converted into two dimensional inequality constraints by integration of angle and voltage, respectively. The optimal control direction is formed by the gradient of control variables, which is obtained by solving the system trajectory expressed by the differential algebraic equations and trajectory sensitivity expressed by the linear time-dependent dynamic system. Test results on the New England 39-bus power system have verified the effectiveness and reliability of the proposed methodology.