Optimal hybrid control of transient stability. Part Two: For cases with different unstable modes

Abstract

Part-I of this two-part paper develops an optimal algorithm for transient stability control to coordinate preventive actions and emergency actions for a subset of contingencies with the same unstable mode. In this part, the cases of several subsets of contingencies with different unstable modes are dealt with. Some preventive actions benefiting a subset of contingencies may go against the stability of others; thus coordination among the optimal schemes for individual subsets is necessary. The coordination is achieved by properly replacing preventive actions with emergency actions for some individual subsets. It is formulated as a classical model of economic dispatch with additional generating costs due to the emergency actions. Such an optimal algorithm is proposed based on the algorithm in the Part-I and verified by simulations on a Chinese power system.