Transient stability preventive control using critical clearing time sensitivity

Power systems have become larger and more complicated because of the increase of the electric power demand, and the analysis of a power system needs heavier computation. On the other hand, the social dependence on electric power is increasing, so the influence of outages in power systems is becoming more crucial. Therefore on-line preventive control is more important than ever. In this paper, we propose a generation rescheduling method for transient stability preventive control. First we sort all contingencies in the decreasing order of their severity. This process is done by sorting all contingencies in the increasing order of their critical clearing times (CCTs) computed using the dynamic extended equal-area criterion. Second we select several contingencies among them as objects of consideration, and compute generation rescheduling amounts using rotor angles of some machines at the appropriate time and the linearity relationship between CCTs and outputs of critical machines. To investigate the validity of the proposed method, simulations carried out using the 9-machine 20-bus system.