An efficient methodology for coherency-based dynamic equivalents

Abstract

The paper presents a new methodology for dynamic equivalents. Two alternative linear simulation methods are proposed for the idenification of coherent generators. The measure of coherency for both methods is the angular speed average deviation of generators. The coherent generators are grouped using a clustering algorithm that assures the uniqueness of the composed coherent groups. The REI approach is applied to transfer the generators of each group to a common busbar. The Levenberg-Marquardt method is used for the coherent generator dynamic aggregation. The dynamic equivalents are evaluated in the New England system and in a configuration of the Brazilian South-Southeastern system with 421 busbars, 717 transmission lines/transformers and 40 generators.