Input-output characteristics of the power transmission network's swing dynamics

Wide deployment of sensing and actuation capabilities in the electric power grid, along with changing dynamical characteristics, are necessitating analysis of power-system swing dynamics from an input-output perspective. In this article, the input-output properties of the swing dynamics, including the finite and infinite zeros, are characterized from a dynamical-networks perspective. Specifically, an explicit algebraic characterization is given for a matrix whose eigenvalues are the zeros, and in turn structural and graph-theoretic conditions for the absence and presence of nonminimum phase dynamics are developed. Based on these structural results and also an illustrative example, it is demonstrated that the zeros of the swing dynamics are important for analyzing transients and oscillations in the power transmission network, using reduced-order models, and designing controls.