A novel SIME and sensitivity based model and algorithm of transient stability constrained optimal power flow

Transient stability constrained optimal power flow (TSCOPF) is a challenging problem of power system. In this paper, TSCOPF is decomposed into three sub-problems, namely transient stability assessment (TSA), the stability constraint constructing and simple TSCOPF. They are solved iteratively to achieve the optimal operation point. In the TSA sub-problem, each contingency is simulated and the stability margin is obtained by using single machine equivalent (SIME) method. In the second sub-problem, the sensitivities of the stability margins with respect to the control variables are obtained via trajectory sensitivity technique, which construct only one linear inequality constraint for each contingency to represent transient stability. The constraints are formulated for general unstable case, extreme unstable case and slight stable case respectively. These above constraints are incorporated into conventional OPF to form the third sub-problem. A correction factor is added into constraint formulation to avoid over-adjustment. The prime-dual interior point method is used to solve the third sub-problem. This proposed method is capable of handling multi-contingency problems of diffident SIME mode and the requirement of stability margin can be met. The effectiveness is validated on the New England 10-generator 39-bus system.