In energy control centers, operators cannot always assure the energy dispatch. This article presents an energy deviation control system; the energy control law is linearly time-variant with a receding control horizon, which allows energy error convergence to zero in finite time; it considers the operational limitations of hydraulic power plants, including a damping mechanism of the transient response that prevents unnecessary changes of mechanical actuators. The control law is easy to implement with low computational load, and it is compatible with conventional SCADA for power systems. The control implementation has reduced the energy deviations by 55%.