Vlad Hasmatuchi

HES-SO Valais-Wallis, Sion, Switzerland · Institut Systèmes industriels

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...

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...

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 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 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...

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...

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...

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...

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...

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...

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 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...

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...

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...

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...

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...

New small-hydro testing infrastructure

A new universal test rig has been installed at the HES-SO VS Sion-Switzerland to assess the hydraulic performances of different types of small-power turbomachines (up to 10 kW) and other hydraulic components with complex geometry, following the IEC 60193 standard recommendations. The closed-loop circuit allows simulating different implantation leve...

A new ducted isokinetic turbine for rivers and artificial channels has been designed. The new (patented) concept consists on an axial turbine with two joined concentric runners: an annular turbine runner and a central pump runner. The aim of the pump runner is to induce a suction effect in the central area in order to increase the axial velocity pa...

The largely unexploited potential of small scale energy hydropower remains crucial the development of new technologies to harvest the hydraulic energy on existing facilities. In this framework, several projects have been set up by the HES-SO Valais//Wallis and the EPFL Laboratory for Hydraulic Machines. One of the developed technologies is a new hy...

The University of Applied Sciences and Arts Western Switzerland – Sion (HES-SO // Valais-Wallis) has installed in its hydraulic laboratory a new universal test rig to assess the hydraulic performances of different types of small-power axial and radial-axial turbines and/or pumps (with a power of up to 10 kW), valves and other hydraulic components w...

Free-surface flow numerical simulations in the tailrace canal of the Swiss Lavey run-of-river hydro powerplant and flow measurements are performed to investigate its isokinetic potential with the aim of installing new technologies to recover the energy of rivers and artificial channels. The canal is supplied by the draft tubes of three Kaplan turbi...

The University of Applied Sciences of Western Switzerland – Sion (HES-SO // Valais-Wallis) has installed in its hydraulic laboratory a new universal test rig to assess the hydraulic performances of different types of small-power axial and radial-axial turbines and/or pumps (less than 15 kW), valves as well as other components of hydraulic systems,...

Les axes de développement de la petite hydraulique

When operated far from their optimum conditions, pump-turbines may exhibit strong hydrodynamic instabilities, often called rotating stall, which lead to substantial increase of vibration and risk of mechanical failure. In the present study, we have investigated the flow filed in a model of radial pump-turbine with the help of tuft visualization, wa...

New Counter-Rotating Micro-Hydro Turbine for Drinking Water Systems

In the recent context of replacing part of nuclear energy production by alternative renewable energy sources, unexploited small-hydro potential sites are reconsidered. The present study focuses on the development of a new axial counter-rotating turbine for small-hydro applications to recover the energy lost in release valves of water supply. A site...

In the recent context of replacing part of nuclear energy production by alternative renewable energy sources, unexploited small-hydro potential sites are reconsidered. The present study focuses on the development of a new axial counter-rotating turbine for small-hydro applications to recover the energy lost in release valves of water supply. A site...

A counter-rotating hydraulic micro-turbine has been developed to recover the energy lost in release valves of water supply network. This compact two-stage axial turbine could be installed in line with the conduit, reducing the infrastructure investments, which is a crucial point for small power plant. The two stages of the turbine allow to use this...

Pressure-Synchronized PIV for Rotating Stall Evidence

A counter rotating hydraulic micro turbine has been developed to recover the energy lost in release valves of water supply network. This compact two stage axial turbine could be installed in line with the conduit, reducing the infrastructure investments, which is a crucial point for small power plant. The two stages of the turbine allow to use this...

Hydrodynamics of a Pump-Turbine Operating at Off-Design Conditions in Generating Mode

An unconventional tuft visualization method, along with an image processing technique adapted to the flow conditions, is proposed and implemented on a reduced-scale model of a Francis-type reversible pump-turbine in three different turbine stages such as turbine mode, runaway mode, and turbine break mode. The main goal of this technique is to visua...

Modern pump-turbines are subject to frequent switching between the pumping and generating modes with extended operation under off-design conditions. Depending on the specific speed of the pump-turbine, the discharge-speed as well as torque-speed generating mode characteristics at constant guide vanes opening can be "S-Shaped". In such a situation,...

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 sequences. However, the fast and frequent switching between pumping mode and generating mode...

We investigate the Rotor-Stator Interaction in a pump-turbine reduced scale model by considering fluid-structure coupling. The pressure fluctuations amplitude in the rotor-stator vaneless gap has generally been shown to increase linearly with the operating specific energy, subjecting the pump-turbines components to high stresses at high head operat...

An experimental investigation of the rotating stall in reduced scale model of a low specific speed radial pump-turbine at runaway and turbine brake conditions in generating mode is achieved. Measurements of wall pressure in the stator are performed along with high-speed flow visualizations in the vaneless gap with the help of air bubbles injection....

Modern pump-turbines are subject to frequent switching between the pumping and generating modes with extended operation under off-design conditions. Depending on the specific speed of the pump-turbine, the discharge-speed as well as torque-speed characteristics at constant guide vanes opening can be “S-Shaped”. In this case, the machine operation m...

Hydrodynamics of a Pump-Turbine Operating at Off-Design Conditions: Experimental Investigation

Modern pump-turbines are subject to frequent switching between the pumping and generating modes with extended operation under off-design conditions. Depending on the specific speed of the pump-turbine, the discharge-speed as well as torque-speed characteristics at constant guide vanes opening can be “S-Shaped”. In this case, the machine operation m...

Hydrodynamics of a Pump-Turbine Operating at Off-Design Conditions: Experimental Investigation

Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes opening are addressed. The computational domain includes the full reduced scale model water passag...

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 sequences. However, the fast and frequent switching between pumping mode and generating mode...

Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes opening are addressed. The computational domain includes the full reduced scale model water passag...

Modern pump-turbines are subject to frequent switching between the pumping and generating modes with extended operation under off-design conditions. Depending on the specific speed of the pump-turbine, the discharge-speed as well as torque-speed characteristics at constant guide vanes opening can be “S-Shaped”. In this case, the machine operation m...

The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. The paper highlights the interaction between vibrating guide vanes and the flow behavior. The...

The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow visualizations in the vaneless space between the impeller and the guide vanes using air bubbles i...

We perform a numerical analysis of the decelerated swirling flow into the discharge cone of a model Francis turbine operated at variable discharge and constant head, using an axisymmetric turbulent swirling flow model and a corresponding simplified computational domain. Inlet boundary conditions correspond to velocity and turbulent kinetic energy p...

In the present study, the fluid-structure coupling is investigated in the guide vanes of a pump-turbine scale model placed in one of the test rigs of the Laboratory for Hydraulic Machines (EPFL) in Lausanne. The paper focuses on the advanced instrumentation used to get reliable and complete fluid-structure coupling results. Semi-conductor strain ga...