As wind power installed capacities increase, it is necessary to deal with the inevitable variability of renewables. Some of that variability can undoubtedly be predicted, but some will in all probability remain unpredictable. In either case, reserve power must be made available. It is clear that the ramp rates that the reserve power must meet will stress technology and call for part-load operation at reduced efficiencies. In the present work, we use a gas turbine (GT) dynamic models to simulate the provision of firm power in the Pennsylvania, New Jersey and Maryland grid, PJM. Rowen GT models [1, 2], well established in the literature, are modified to take into account GT ramp rates constrains and fuel consumption at full and partial load, as well as during startup and shutdown. The GTs operational requirements for two summer days in the PJM area are determined, by selecting their number and capacities to result on at least a few units operating at full load. The dynamic models [1, 2] are implemented in the VisSim simulation environment. The results of the work show how the chosen GTs must be operated to provide firm power. Although the operational strategy determined in this paper meets the firm power, in two occasions during the day excess power is produced during a few minutes, to avoid ramping the units down too fast.