Amélioration de la stabilité de fonctionnement des turbines Francis par contrôle actif - Etude de faisabilité

Improving the Operation Stability of Francis Turbines by Active Control - A Feasibility Study

¹ EPFL-IMHEF-LMH, Lausanne
² EDF-DER, Chatou

Abstract

Francis turbines, operating at off-design conditions, generate hydraulic disturbances in the hydraulic circuit. In certain cases, the amplitude of the dynamic response of the system to these excitations can inhibit normal usage of the plant. One approach to reduce the amplitude fluctuations is to deliberalely excite the system with the inverse of the naturally generaled disturbances. The idea is to minimize the overall amplitude of the fluctuations by actively controlling the system. Experimental results were obtained with a rotating valve exciter mounted on a laboratory test rig equipped with a Francis turbine. The actuator modulales the flow injected into the circuit. The external excitation system has been tested at different places of water intake and injection. The results confirm that a small excitation flow can significantly reduce the amplitude of pressure fluctuations transmitted to the feed pipe.