Krishna S

Online dynamic security assessment involves analyzing the effect of a large number of contingencies in a short time. This is a computationally demanding task, and use of energy function method reduces the computational burden. Energy function method involves determination of a quantity called critical energy which requires system simulation for a short duration. In spite of the use of energy function method, there is a significant computational requirement since a large number of contingencies have to be analyzed. In this paper, a comparison of the performance, in terms of accuracy and speed, of different numerical methods in the determination of critical energy, is presented.

Online dynamic security assessment (DSA) is a computationally intensive task. In order to reduce the amount of computation, screening of contingencies is performed. Screening involves analyzing the contingencies with the system described by a simpler model so that computation requirement is reduced. Screening identifies those contingencies which are sure to not cause instability and hence can be eliminated from further scrutiny. The numerical method and the step size used for screening should be chosen with a compromise between speed and accuracy. This paper proposes use of energy function as a measure of error in the numerical solution used for screening contingencies. The proposed measure of error can be used to determine the most accurate numerical method satisfying the time constraint of online DSA. Case studies on 17 generator system are reported.