Transient security assessment using multivariate polynomial approximation

This paper presents an efficient method for transient security assessment. The proposed method exploits the computational efficiency of linear estimation methods to determine an accurate nonlinear mapping function. The novelty of the proposed method is that a nonlinear transformation is applied to the original variables, voltage magnitudes and phase angles, so that the mapping function is approximately linear in terms of the transformed variables. The linear function obtained using the transformed variables is indeed nonlinear in terms of original variables. The attractiveness of this method is that the estimated function is not a linearized approximation although a linear estimation method is used. The potential of the proposed method is demonstrated using the New England 39-bus system and a larger power system with 470 buses.