Publications de Sébastien Alligné

Turbine mode start-up simulation of a FSFC variable speed pump-turbine prototype - Part I: 1D simulation

François Avellan, Antoine Béguin, Sébastien Alligné, Drazen Dujic

Variable speed hydroelectric units equipped with full size frequency converter (FSFC) offer high operational flexibility enabling fast operating point transitions which increase grid regulation capacities. The XFLEX HYDRO H2020 European research project ai ...

IOP PUBLISHING LTD2021

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

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

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, Christian Landry, Sébastien Alligné, Joao Gomes Pereira Junior, Arthur Tristan Favrel

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, Christian Landry, Sébastien Alligné, Joao Gomes Pereira Junior, Arthur Tristan Favrel, Loïc Andolfatto

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

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

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

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

Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

François Avellan, Andres Müller, Christian Landry, Sébastien Alligné, Arthur Tristan Favrel, Keita Yamamoto

At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of t ...

2017

RANS computations for identification of 1-D cavitation model parameters: application to full load cavitation vortex rope

François Avellan, Christophe Nicolet, Andres Müller, Sébastien Alligné

Due to the massive penetration of alternative renewable energies, hydropower is a key energy conversion technology for stabilizing the electrical power network by using hydraulic machines at off design operating conditions. At full load, the axisymmetric c ...

2017

RANS computations for identification of 1-D cavitation model parameters: application to full load cavitation vortex rope

François Avellan, Christophe Nicolet, Andres Müller, Sébastien Alligné

Due to the massive penetration of alternative renewable energies, hydropower is a key energy conversion technology for stabilizing the electrical power network by using hydraulic machines at off design operating conditions. At full load, the axisymmetric c ...

International Association For Hydraulic Research2016

Measurement of the Self-Oscillating Vortex Rope Dynamics for Hydroacoustic Stability Analysis

François Avellan, Sébastien Alligné, Keita Yamamoto

Flow instabilities in hydraulic machines often feature oscillating cavitation volumes, which locally introduce compliance and mass flow gain effects. These unsteady characteristics play a crucial role in one-dimensional stability models and can be determin ...

American Society of Mechanical Engineers2016

Hydroelectric System Response to Part Load Vortex Rope Excitation

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

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 ...

International Association For Hydraulic Research2016

Identification of the wave speed and the second viscosity in cavitating flow with 2D RANS computations - Part II

François Avellan, Sébastien Alligné

The 1D modelling of cavitation vortex rope dynamics in Francis turbine draft tube is decisive for prediction of pressure fluctuations in the system. However, models are defined with parameters which values must be quantified either experimentally or numeri ...

Iop Publishing Ltd2015

Identification of the wave speed and the second viscosity of cavitation flows with 2D RANS computations - Part I

François Avellan, Sébastien Alligné

1D hydro-electric models are useful to predict dynamic behaviour of hydro-power plants. Regarding vortex rope and cavitation surge in Francis turbines, the 1D models require some inputs that can be provided by numerical simulations. In this paper, a 2D cav ...

Iop Publishing Ltd2015

Francis turbine draft tube modelling for prediction of pressure fluctuations on prototype

François Avellan, Christian Landry, Sébastien Alligné, Arthur Tristan Favrel

The prediction of pressure 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 research project Hy ...

Iop Publishing Ltd2015

Forced response analysis of hydroelectric systems

François Avellan, Basile Kawkabani, Philippe Allenbach, Christophe Nicolet, Antoine Béguin, Sébastien Alligné, Pedro Camilo de Oliveira e Silva

At off-design operating points, Francis turbines develop cavitation vortex rope in the draft tube which may interact with the hydraulic system. Risk resonance assessment by means of eigenmodes computation of the system is usually performed. However, the sy ...

International Association For Hydraulic Research2014

A fully modular tool for small-signal stability analysis of hydroelectric systems

Basile Kawkabani, Philippe Allenbach, Sébastien Alligné, Pedro Camilo de Oliveira e Silva

In electrical systems, the small-signal stability analysis method is usually applied to synchronous machines by using the Park representation (d, q-components). This paper presents the generalization of a different approach for this method, based on a, b, ...

IEEE2014

Parametric study of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in generation mode with particular attention to the possible draft tube water column separation. First, the model of ...

Soc Hydrotechnique France2012

Simulation of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in turbine mode with focus on possible draft tube water column separation. The model of a pumped storage power plant ...

International Association For Hydraulic Research2012

Cavitation influence on hydroacoustic resonance in pipe

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Sébastien Alligné

In pipe systems, pressure and flow fluctuations below cutoff frequency propagate as plane waves along pipes. Depending on the pipe length and propagation velocity, resonance leading to high amplitude pressure fluctuation may occur. At low pressure, cavitat ...

Elsevier2012

Forced and Self Oscillations of Hydraulic Systems Induced by Cavitation Vortex Rope of Francis Turbines

Sébastien Alligné

With economical energy market strategies based on instantaneous pricings of electricity as function of the demand or the predictions, operators harness more hydroelectric facilities to off-design operating points to cover the variations of the electricity ...

EPFL2011

Non-Linear Stability Analysis of a Reduced Scale Model Pump-Turbine at Off-Design Operation

François Avellan, Andres Müller, Steven Roth, Christian Landry, Vlad Hasmatuchi, Sébastien Alligné

Nowadays, the pump-storage power plants are a proven solution for storing electricity at large scale and offering flexibility to the power management. Therefore, the hydraulic machines are increasingly subject to off-design operation, start-up and shutdown ...

2011