Flatness-based control of an hydro power plant

Power-frequency control constitutes an Ancillary Service provided by power plants for the electrical power system stability. In France, grid requirements impose a fast and stable dynamic response of generating units allocated to this service. For hydroelectric power plants with surge tank, these control performance can be difficult to guarantee for all operating points in an interconnected power system. This paper presents a robust control law based on the nonlinear flatness for the speed governor of hydraulic turbine control system participating to power-frequency control. Comparison of this nonlinear structure with a linear PI feedforward controller gives better results: lower overshoot and less sensitive with process variations.