A Model Reference Approach for Interarea Modal Damping in Large Power Systems

In this chapter, we present a set of results on the design of dynamic controllers for electromechanical oscillation damping in large power systems using Synchronized Phasor Measurements. Our approach consists of three steps, namely – (1) Model Reduction, where phasor data are used to identify second-order models of the oscillation clusters of the system, (2) Aggregate Control, where state-feedback controllers are designed to achieve a desired closed-loop transient response between every pair of clusters, and finally (3) Control Inversion, where the aggregate control design is distributed and tuned to actual realistic controllers at the generator terminals until the interarea responses of the full-order power system matches the respective inter-machine responses of the reduced-order system. Although a general optimization framework is needed to formulate these three steps for any n-area power system, we specifically show that model reference control (MRC) can be an excellent choice to solve this damping problem when the power system consists of two dominant areas, or equivalently one dominant interarea mode. Application of MRC to such two-area systems is demonstrated through topological examples inspired by realistic transfer paths in the US grid.