Wind turbines in a wind farm are operated individually to maximize their own power regardless of the impact of aerodynamic interactions on neighboring turbines. There is the potential to increase power and reduce overall structural loads by properly coordinating the turbines. To perform control design and analysis, a model needs to be of low computational complexity but retain the necessary dynamics seen in high-fidelity models. This paper addresses a model reduction approach that computes the dominant modes of the flow that capture the energy and frequency characteristics of the system. Specifically, the paper uses the balanced proper orthogonal decomposition technique to construct the dominant input/output modes. Using these modes, a low-order model of a wind farm is constructed that can be used for control design.