This paper presents a wind turbine generator (WTG) reduced-order model for time domain simulations. Selective modal analysis is used to reduce the model order by focusing on the most relevant modes and variables. In most cases, a single relevant mode is found; thus, a first-order model that captures the relevant mode is derived. Depending on the WTG dynamics, in some cases, reduced-order models of higher order are required. The proposed model is applied to both 4-bus and 39-bus test systems. The results show that the proposed reduced-order model closely resembles the impact of WTGs in a power system, even when large perturbations occur. Line and synchronous generator (SG) outages are taken into account. The proposed model reduces the simulation time and the power system model complexity. (C) 2010 Elsevier B.V. All rights reserved.