Cecile Münch

University of Applied Sciences and Arts Western Switzerland · Hydraulic

Hydropower is a key source of electricity production for allowing the integration of intermittent renewable energy resources. Among the various hydraulic power plants around the world, the ones equipped with Pelton turbines already provide large flexibility that is still enhanced with the development, for instance, of the hydraulic short circuit op...

The need to decarbonize our energy production push us toward the use of renewable sources such as solar, wind and hydraulic energies. These renewable energies often suffer from intermittences which requires flexibility from the dispatchable energy producers to respond to power changes and to ensure a stable electrical grid. For this specific purpos...

In the framework of the XFLEX HYDRO H2020 European Project, a 5 MW reversible Francis pump-turbine prototype, equipped with an industrial full size frequency converter, is investigated to demonstrate enhanced grid regulation capacities of variable speed hydropower units. The targeted high flexibility operation modes imply increased numbers of start...

Energy storage through pumped-storage (PSP) hydropower plants is currently the only mature large-scale electricity storage solution with a global installed capacity of over 100 GW. The objective of this study is to evaluate the possibility of using this storage solution on a smaller scale to provide local voltage control and line congestion managem...

In Switzerland, during the last decade, the development of the new renewable energies (small hydro, solar, wind…) has been promoted by a specific feed-in tariff. However, the regulator schedules to remove this specific measure to force the producers to match the demand. Regarding the small hydropower plants, this change requires to increase the fle...

In most of the Swiss Alpine regions, the availability of water resources for irrigation is usually adequate, even in period of drought, as evidenced by the summers of 2003 and 2018. Indeed, important natural stocks are for the moment available in the form of snow and ice, but the situation is likely to change in the future considering global and re...

Variable speed hydropower units offer a large spectrum of grid regulation services and may therefore contribute to the stability of future power supply systems. Full Size Frequency Converters (FSFC) already found real world application in Pumped Storage Hydropower Plants up to a rated power of 100 MW and are even considered scalable up to a few hun...

The mode split on disc like structures rotating in a dense fluid leads to a deviation of eigenfrequencies at high rotational speeds compared to their values in still water. Predicting eigenfrequencies correctly is essential to avoid fatigue cracks on prototype turbine runners. Analytical models for simple geometric configurations and complex numeri...

The operating modes of pumped storage power plants, such as that of the Forces Motrices Hongrin-Léman (FMHL) in Switzerland, have drastically changed over the past decades due to the emergence of new renewable energies. The number of starts and stops experienced by machines increased significantly leading to broader fatigue cycles on the different...

Operating hydro turbines in off-design conditions increases the risk of cavitation occurrence, which in turn, leads to numerous problems such as performance degradations, structural vibrations, and most importantly, mechanical damage due to erosion. It is therefore crucial to develop a monitoring system that detects the occurrence and severity of c...

The need to decarbonise our energy system push us toward the use of different clean renewable energy sources, such as solar, wind and hydroelectric energy. It is well known that some of these renewable energy sources suffer of intermittence, which requires the conventional dispatchable power plants to become more flexible to respond to any power ch...

In the framework of the XFLEX HYDRO H2020 European Project, the pumped-storage power plant of Grand’Maison (France), owned by Electricité De France, focuses on the implementation of the hydraulic short-circuit (HSC) operating mode. This mode increases the flexibility in pumping mode, which helps the integration of intermittent energies. Grand’Maiso...

The stability of the electricity grid will be disrupted by the massive integration of new renewable energies. Hydropower plants have a major role to play in this transformation of the electricity market by increasing their operational flexibility and their ability to provide ancillary services. However, this flexibility may lead to an accelerated d...

RÉSUMÉ Le développement des nouvelles sources d’énergie renouvelable de nature intermittente nécessite de disposer de sources d’énergie flexibles également d’origine renouvelable afin de garantir la stabilité du réseau électrique et les engagements environnementaux. Dans le cadre du projet pilote et démonstrateur « SmallFlex », l’augmentation de la...

To enhance the sustainability of water supply systems, the development of new technologies for micro scale hydropower remains an active field of research. The present paper deals with the implementation of a new micro-hydroelectric system for drinking water facilities, targeting a gross capacity between 5 kW and 25 kW. A counter-rotating microturbi...

Energy storage through pumped-storage (PSP) hydropower plants is currently the only mature large-scale electricity storage solution with a global installed capacity of over 100 GW. The objective of this study is to evaluate the possibility of using this storage solution on a smaller scale to provide local voltage control and line congestion managem...

Hydropower is a key energy conversion technology for stabilizing electrical power. When running at full load, a 3-D cavitation vortex rope develops in Francis turbines that acts as an internal source of energy and instability. 1-D models allow this phenomenon to be predicted and the range of safe operating points to be defined. These models involve...

Over the last two decades, the public policies for promoting new renewable energies allowed the growth of such energies around the world. Due to their success, the policies are changing, forcing the producers to adapt their strategy. For instance, in Switzerland, the feed-in tariff system has been modified in 2018 to promote an electricity producti...

The need to decarbonize our energy production push us toward the use of renewable sources such as solar, wind and hydraulic energies. These renewable energies often suffer from intermittences which requires flexibility from the dispatchable energy producers to respond to power changes and to ensure a stable electrical grid. For this specific purpos...

The Z’Mutt pumping station, part of the Grande Dixence hydroelectric scheme, is one of the demonstrators of the XFLEX HYDRO project. A 5 MW reversible pump-turbine prototype equipped with a full-size frequency converter (FSFC) is used to investigate dynamic variable speed operation in pumping and generating mode. Since the FSFC converter is always...

In the framework of the XFLEX HYDRO H2020 European Project, one of the demonstrators focuses on the implementation of the hydraulic short-circuit on the pump storage power plant of Grand-Maison owned by Electricité De France (EDF). The Grand-Maison power plant is a two-level plant production with one plant located above the downstream reservoir and...

In the framework of the new Swiss feed-in-tariff system for Small Hydropower Plants (SHP), the aim of the SmallFLEX project, led by HES-SO Valais and performed in collaboration with EPFL, WSL, EAWAG, PVE and FMV, is to show how SHP can provide winter peak energy and ancillary services, whilst remaining eco-compatible. The pilot and demonstrator sit...

In the framework of the new feed-in-tariff system in Switzerland for Small Hydropower Plants (SHP), the aim of the SmallFLEX project, led by HES-SO Valais and performed in collaboration with EPFL, WSL, EAWAG, PVE, and FMV, is to show how SHP can provide winter peak energy and ancillary services, whilst remaining eco-compatible. The pilot and demons...

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 aims to demonstrate flexibility of such technology at prototype scale. The Z’Mutt pumping statio...

Diagnostic de la fatigue prématurée des turbines I Dans le contexte récent d'exploitation des réseaux électriques, la nécessité d'augmenter la flexibilité des centrales hydroélectriques peut induire une fatigue prématurée sur certains composants. Une étude menée sur une turbine Francis de 100 MW a permis d'élaborer un protocole de diagnostic grâce...

The flow in a Francis turbine at full load is characterised by the development of an axial vortex rope in the draft tube. The vortex rope often promotes cavitation if the turbine is operated at a sufficiently low Thoma number. Furthermore, the vortex rope can evolve from a stable to an unstable behaviour. For CFD, such a flow is a challenge since i...

The development of cavitation sheets over an hydrofoil is driven both by the gas content of the liquid and the nature of the boundary layer that develops along the hydrofoil. For a deaerated water and a flow at high Reynolds number and/or high angle of attack, the boundary layer is fully turbulent and the cavitation sheet develops from the leading...

The study focuses on a booster pump used to feed the main pump of one unit of the FMHL hydropower plant (Veytaux I). From the beginning of the operation of the power plant, vibrations have been observed on this booster pump with sometimes the presence of cavitation erosion. The visualisations carried out show that a cavitating vortex develops at th...

This work focuses on a 100 MW Francis turbine prototype, part of one of the four horizontal ternary groups of Grimsel 2 PSPP, in Switzerland. Due to the massive integration of new renewable energy, the number of daily starts/stops of the machines has increased. Consequently, cracks on the runner blades of the Francis turbines have been noticed, wit...

Hydropower has consistently played a major role in energy policies around the globe for the past century, due to its outstanding capability of reliably and flexibly supplying clean electricity. Along with that, enormous capacities of other renewable energy sources have been added to the electricity mix over the past decades, such as solar or wind p...

In the framework of the FlexStor project, an in-situ experimental investigation has been conducted on a 100 MW Francis turbine prototype following the identification of signs of fatigue on the runner blades, possibly correlated with the drastic increase of the number of daily starts/stops in the recent years. To this end, two synchronised sets of m...

After the performance assessment of a new hydrokinetic turbine prototype in the tailrace channel of a run-of-river power plant (Lavey, CH), the possibility to install a farm of such hydrokinetic turbines on this pilot site is investigated. In order to identify the optimal number and size of the machines as well as their location on this site, numer...

Due to the increasing integration of new renewable energies, the electrical grid undergoes more frequent instabilities. Hydroelectric power plants, particularly pumped storage plants, are well suited for grid control. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by and s...

Run-off-river hydro projects can create sustainable energy minimizing impacts to the surrounding environment. Among many advantages of these systems, whose development has in fact been largely supported during the past years by the confederation, their main limitation is that their functioning is dependent by the available discharge, as they do not...

Objectives Smart storage operations (SSO) have been implemented on an alpine runoff river HPP (case study: KW Gletsch-Oberwald HPP) in order to enhance the flexibility of the power plant (ref poster SmallFlex). SSO operations consist on the use of available space underground, such as the settling basin, in order to store the water, particularly in...

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, wh...

The study is motivated by the fact that cracks on the runner blades of a 100 MW Francis turbine prototype have been noticed. The possible origin: a drastic increase of the number of daily starts/stops in the recent years. To this end, an in-situ experimental investigation using two synchronised sets of measurements has been conducted: the first one...

During the design and optimization of hydraulic turbomachines, the experimental evaluation of hydraulic performances beyond the best efficiency point and for off-design conditions remains essential to validate the simulation process and to finalize the development. In this context, an alternative faster method to measure the efficiency of hydraulic...

The development of energy recovery systems on existing water utility networks is a new challenge for increasing the sustainability of electricity generation mix. The concept of the new micro-turbine with counter rotating runners braces this goal by allowing the recovery of the energy which is spoiled in pressure reducing valves in many water supply...

An experimental investigation to measure the performance of a first prototype of a kinetic turbine is presented. This turbine, developed using numerical simulation, recovers the kinetic energy of water in free surface canals. To assess the performance of the machine, a first prototype as well as an open-air platform were built, both installed in th...

In the course of the massive penetration of alternative renewable energies, the stabilization of the electrical power network significantly relies on the off-design operation of turbines and pump-turbines in hydropower plants. The occurrence of cavitation is, however, a common phenomenon at such operating conditions, often leading to critical flow...

Le pompage-turbinage à petite échelle recèle de nombreux avantages | Grâce à sa capacité de stockage, une station de transfert d’énergie par pompage-turbinage à petite échelle est à même de contribuer à l’intégration des énergies renouvelables intermittentes et de procurer à un prix compétitif les services système que ne fournissent pas ces nouveau...

Cavitating tip-leakage vortices appear in several hydrodynamic flows such as marine propellers or Kaplan turbines. Cavitating computations are a challenging topic since several keys issues are an ongoing work such as the definition of a universal mass source term. The present study focuses on the computations of the tip-leakage vortex including the...

Due to the penetration of alternative renewable energies, the stabilization of the electrical power network relies on the off-design operation of turbines and pump-turbines in hydro-power plants. The occurrence of cavitation is however a common phenomenon at such operating conditions, often leading to critical flow instabilities which undercut the...

In the actual context of Swiss nuclear phase-out strategy, harvesting the extensive potential of small hydropower (<10MW), in particular on existing infrastructure, is a priority. In this framework, a new kinetic turbine has been jointly developed between the HES-SO Valais//Wallis and Stahleinbau Gmbh in Switzerland, to harvest the kinetic energy o...

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 cavitation vortex rope developing in Francis turbines acts as an internal source of energy, lea...

Micro-hydropower is a way of improving the energetic efficiency of existent water systems. In the particular case of drinking water systems, several studies have showed that pressure reducing valves can be by-passed with turbines in order to recover the dissipated hydraulic energy to produce electricity. As conventional turbines are not always cost...

Wherever relief valves and other energy dissipation devices are installed to limit the pressure, water utility networks provide unexploited hydropower potentials. This is mainly due to a lack of economically viable technologies for energy recovery in the pico and micro hydropower range below 100 kW. Micro-turbine with counter-rotating runners prove...

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 cavitation vortex rope developing in Francis turbines acts as an internal source of energy, lea...

Considering the nuclear phase-out strategy of several European countries and the future tendency to promote renewable energies, the exploitation of small hydropower sites (<10 MW) becomes increasingly important. In this framework DuoTurbo Turbine, a new DuoTurbo-microturbine prototype for drinking water networks has been jointly developed by the HE...

Nowadays, high-head power plants could increase their installed power capacity for many reasons, e.g. dam heightening, increase of their peak power capacity or refurbishment with new turbines. Frequently, due to several considerations, e.g. topographical or economical limitations, the existing surge tank cannot be extended to keep previous safety l...

The present work introduces the implementation and validation of a faster method to measure experimentally the efficiency characteristics of hydraulic turbomachines at a model scale on a test rig. The case study is represented by a laboratory prototype of an in-line axial microturbine for water supply networks. The 2.65 kW one-stage variable speed...

Motivation - Standard efficiency measurements on model testing: point-by-point method •Proved, but laborious and time expensive •Small hydro development: the investment is much more limited compared to large hydro -Alternative faster solution: dynamic method •The “Sliding gate” dynamic method (Almquist et al. 1997) is successfully used for index te...

The interest in micro-hydropower in existing infrastructure is increasing since this is a technology with low environmental impacts and potential for energy recovery in different types of installation. The technologies available for these schemes are still restricted and it is a current subject for research. In this work an experimental characteriz...

In large cities, pollution composed of many different chemical components and small particles is an important public health problem that affects especially children and people presenting breathing difficulties. One challenge for public authorities is to respect the norms given by the central state, but how? Today, concrete methods for reducing poll...

Micro-hydropower is a way of improving the energetic efficiency of existent water systems. In the particular case of drinking water systems, several studies have showed that pressure reducing valves can be by-passed with turbines in order to recover the dissipated hydraulic energy to produce electricity. As conventional turbines are not always cost...

The present study is related to the development of the tip vortex cavitation in Kaplan turbines. The investigation is carried out on a simplified test case consisting of a NACA0009 blade with a gap between the blade tip and the side wall. Computations with and without cavitation are performed using a R ANS modelling and a transport equation for the...

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 cavitating Venturi is considered. URANS computations are performed to investigate the dynamic beh...