Publications de Christophe Nicolet

On the prediction of the induced damage by the start-up sequence of Francis turbines: On operational resilience framework

Mario Paolone, Christophe Nicolet, Elena Vagnoni, Martin Seydoux

The number of transient operations in hydraulic machinery connected to power grid, notably start-ups and shut-downs, has observed a substantial increase in recent decades, primarily driven by the global shift toward intermittent renewable energy sources. S ...

Pergamon-Elsevier Science Ltd2024

Procedure for predicting part load resonance in Francis turbine hydropower units based on swirl number and local cavitation coefficient similitude

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Loïc Andolfatto, Sébastien Alligné

Francis turbines operating at part load conditions develop a cavitation precessing vortex known as a vortex rope in the draft tube cone below the runner outlet. At part load conditions, this vortex precession acts as an excitation source inducing pressure ...

ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD2019

Reduced scale model testing for prediction of eigenfrequencies and hydro-acoustic resonances in hydropower plants operating in off-design conditions

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Joao Gomes Pereira Junior, Christian Landry, Sébastien Alligné

The massive penetration of the electrical network by renewable energy sources, such as wind and solar, pushes the operators to extend hydropower plant units operating range to meet the transmission system operator requirements. However, in off-design opera ...

2019

Prediction of hydro-acoustic resonances in hydropower plants by a new approach based on the concept of swirl number

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Sébastien Alligné, Loïc Andolfatto, Joao Gomes Pereira Junior

Hydropower plant units operating in off-design conditions are subject to cavitation flow instabilities, potentially inducing hydro-acoustic resonances under certain conditions. They can be predicted by using one-dimensional numerical models of hydropower p ...

Taylor & Francis Ltd2019

Hydropower Plants Frequency Regulation Depending on Upper Reservoir Water Level

Philippe Allenbach, Christophe Nicolet

This paper presents a novel method of hydro power plant operation, based on the control of the injectors’ or wicked gates opening time as a function of the upper reservoir level. In this way, a faster power injection, depending on the current water level o ...

2019

Renovation of hydraulic power plant: how to select the best technical options?

François Avellan, Christophe Nicolet, Christian Landry, Loïc Andolfatto, Joao Gomes Pereira Junior

With the Energy Strategy 2050, Switzerland wishes to focus on balanced utilization of hydropower potentials and new renewable energy sources to cope with nuclear energy phasing out. Integration of large amounts of new renewable energies such as wind and so ...

2018

New insight in Francis turbine cavitation vortex rope: role of the runner outlet flow swirl number

François Avellan, Christian Landry, Christophe Nicolet, Joao Gomes Pereira Junior, Arthur Tristan Favrel, Andres Müller

At part load operation, Francis turbines experience the development of a cavitation vortex rope in the draft tube, whose precession acts as a pressure excitation source. In case of resonance, the resulting pressure pulsations lead to unacceptable torque an ...

Taylor & Francis Ltd2018

Measurements of Cavitation Compliance in the Draft Tube Cone of a Reduced Scale Francis Turbine Operating at Part Load

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Joao Gomes Pereira Junior

Francis turbines operating at part load conditions typically experience a cavitation vortex rope immediately at the runner outlet. As the compliance of this cavitation flow is much higher than the one in cavitation-free conditions, a decrease in the value ...

2018

Prediction of Francis Turbine Prototype Part Load Pressure and Output Power Fluctuations with Hydroelectric Model

François Avellan, Christophe Nicolet, Christian Landry, Sébastien Alligné, Joao Gomes Pereira Junior, Antoine Béguin

The prediction of pressure and output power fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 re ...

2017

Simulation of pump-turbine prototype fast mode transition for grid stability support

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Antoine Béguin, Olivier Braun

The paper explores the additional services that Full Size Frequency Converter, FSFC, solution can provide for the case of an existing pumped storage power plant of 2x210 MW, for which conversion from fixed speed to variable speed is investigated with a foc ...

2017