Incorporating energy-intensive enterprises (EIEs) in power system unit commitments is beneficial for both power systems and EIEs. However, power systems and EIEs are typically operated by different entities, making it impractical to incorporate a full EIE model in the unit commitment because of the increasing model dimensions and consequent calculation efficiency and privacy issues. Therefore, a robust aggregate model (RAM) of the EIE is developed in this paper to simplify the detailed EIE model as a conventional generator; which ensures the robustness of the simplified model, i.e., all possible dispatch signals from system operators can be realized by EIEs. The flexibility of EIEs and the corresponding cost are also retained in the RAM. To obtain the technical parameters of the RAM, a two-stage robust problem is developed, and a modified column-constraint-generation solution method is proposed. In addition, the economic parameters of the RAM are obtained based on the upper convex hull of an EIE's maximum cost under given dispatch signals. With the proposed RAM, the dimensions and calculation time of the unit commitment incorporating EIEs are drastically decreased, and the EIE can reduce production costs while the system operator can reduce operational costs and increase wind integration.