A fast technique for outage studies in power system planning and operation

Security monitoring is a fundamental aspect of the operation of power systems. One of the basic tools that dispatchers use to assess the system security is contingency analysis. This program simulates the state of the system after the sudden loss of an element of production or transmission. The DC load flow used in the determination of the performance index (PI) yields only the real power loading of circuits, and ignores the effects of the bus voltage. Therefore, we present an AC active power model in this paper where the effect of the voltage magnitudes is considered. The changes of the coefficient matrix model due to the line outage are directly determined without reconstruction of that matrix or redetermination of its inverse. Then, the postoutage angle is obtained directly. A derivation of the PI is presented, including only the overloaded lines as a result of the fast contingency screening approach proposed in the paper. Real and practical values of the line power limits required for PI calculations are considered. Furthermore, a simple method for the determination of some matrices included in the PI formulation is introduced in this paper to reduce the computation time compared with that for the Wollenberg-Mikolinnas algorithm. The proposed approach is applied to an IEEE 14-node system and the ranking table is obtained. The proposed method was found to be excellent.