Grand Maison hydropower plant in the French Alps tests new smart technology for improved efficiency and flexibility
The Grand Maison hydroelectric power station, owned and operated by Electricité de France (EDF), is the largest hydropower facility in France and the biggest pumped storage hydroelectric facility in Europe. Located in the Romanche valley of the French Alps, the facility comprises a rock-filled embankment dam that creates the upper reservoir, Lac de Grand Maison, and an artificial lower reservoir, Lac du Verney. The facility has two powerhouses, including an above-ground powerhouse equipped with Pelton turbine generator units and an underground powerhouse equipped with reversible, four-stage Francis pump-turbine units.
The Grand Maison facility operates as a peaking power plant, pumping water from the lower reservoir to the upper reservoir for storage during periods of low electricity demand and releasing the stored water for power generation when the demand is high. The facility has been chosen as one of the demonstration sites for the EU-funded XFLEX HYDRO project, which aims to test a set of smart technologies for boosting the grid stabilisation capability of hydroelectric facilities. The Grand Maison site will demonstrate the Hydraulic Short Circuit (HSC) technology for advanced control and efficiency, using new turbine runners and advanced automation techniques to enhance grid flexibility services. The demonstration project involves the participation of EDF, Ecole Polytechnique Fédérale de Lausanne (EPFL), HES-SO University, Power Vision Engineering, and GE.
During the project, one of the four Pelton turbines at Grand Maison will be operated using HSC mode to offer a new option of frequency control in pumping mode. For this purpose, new turbine runners and smart digital controls have been implemented for efficiency and flexibility improvements.
The project’s initial phase focused on modelling and computer science, which was performed by project partners. The plant controls and the master optimization algorithm had to be updated to allow for the simultaneous operation of the pumps and turbines, which is the core of the HSC.
Several Swiss organizations, including Power Vision Engineering and HES-SO Valais-Wallis, are involved in the project and have contributed to the modelling and computer simulation. A 1-D simulation model of the whole plant was established and validated with measurements to ensure safe and reliable operation with increased flexibility.
The project has undergone two test campaigns, and a successful trial of the demonstration was conducted for two weeks in June. The official demonstration started in September 2021 and will continue until 2023. The project partners are confident that the HSC at the Grand Maison scheme can become an industrial operating mode.
