Fatigue Strength Analysis of a Prototype Francis Turbine in a Multilevel Lifetime Assessment Procedure Part II: Method Application and Numerical Investigation

Part I of the publication series addressed the fundamentals of lifetime assessment of prototype Francis turbines. This paper (Part II) focuses on the numerical part of the procedure. The essential steps and requirements shall be presented (background). The starting points for the numerical considerations are the pressure fields of the transient CFD simulations, which are exported per time step and applied to the existing structure via a fluid–structure interaction. That enables a transient mechanical stress calculation to be conducted, resulting in the fatigue analysis of the component to estimate the remaining lifetime. The individual model requirements should be represented accordingly and applied to the prototype facility (method). The results obtained from this application should be discussed and evaluated. It has to be mentioned that the validation of the numerical results will be performed at Part IV of this publication series (results). The present paper will end up discussing the results and conclusions about further data processing (Conclusion)

Fatigue Strength Analysis of a Prototype Francis Turbine in a Multilevel Lifetime Assessment Procedure Part I: Background, Theory and Assessment Procedure Development

Electricity generation is becoming increasingly flexible in Europe these days. Due to the integration of new renewable energy sources like wind and photovoltaic, other conventional resources, such as hydropower, operate within a brought range around their best efficiency point, thus leading to higher dynamical loads at the water-bearing parts, especially at the runner and the guide vanes (background). By scrutinizing the literature of the past years, one could summarize the outcome in that way, that research projects focused either on model measurements with higher visual accessibility or, less often, on prototype measurements in existing power plants. Today prototype measurements are performed, if possible, to eliminate scaling effects. Moreover, increasing computing power allows prototype simulations to be carried out within a reasonable time. At the acknowledged research projects, prototype and model measurements and numerical simulations have been performed to identify the main gaps in Francis turbines’ lifetime assessment (methods). One special outcome of these investigations was the impracticality of numerical simulations and calculation time, respectively, of start and stop events. Therefore, a prototype measurement with focus at this operating point should be performed to provide more data and an insight into the unit’s behavior. The future goal is a comprehensive machine unit lifetime assessment of the water-bearing parts in a Francis turbine machine set (results). This complex task needs several steps, beginning from measurements through simulations towards data processing. A particular challenge is posed, when the assessment methods are applied to old machines

An Approach to Evaluate the Lifetime of a High Head Francis Runner

International audienceNowadays, the electricity market is changing rapidly and the requirements for hydropower plant operators vary between base load electricity production and ancillary services with a high share of transient operational points. The institute for Energy Systems and Thermodynamics, together with partners from the industry, initiated a research project to investigate the effects of these new operational modes on the components of a hydraulic machine. Especially the runner is of high importance due to the long service time and unfavorable flow phenomena when operated at off design points. A method to evaluate the lifetime of a high head Francis runner should be developed to investigate the existing runner and to serve later on a possible procedure for the design stage. Therefore, prototype measurements with applied strain gauges have been carried out for validation purposes of the developed method. Unsteady Numerical flow simulations using the open-source software OpenFOAM and static as well as dynamic Finite Element calculations with Code Aster are performed to investigate the lifetime of the observed Francis runner. The research project is still ongoing but first results regarding the procedure and the methods will be shown in this paper

A concept for sustainable and digitalized hydropower going beyond the sustainable hydropower sustainability tool

The EU energy policy has the ambitious objective to become the first carbon-neutral continent in the world. In order to achieve this objective hydropower will have to play an essential role as energy source and energy storage in pump storage facilities. Hydropower is a clean, low carbon, and cost-efficient energy source that can be exploited sustainably if an adequate management system is implemented. Nevertheless, in the past, hydropower operations have led to conflicting interests over water usage, impacts on aquatic flora and fauna, and significant socio-economic implications. In order to avoid and mitigate possible negative consequences of hydropower plants the Hydropower Sustainability Assessment Protocol (HSAP, https://www.hydrosustainability.org/) provides a helpful tool to minimize related impacts. In this presentation we will delineate how the 26 topics of the HSAP could be complemented in order to provide a fully digitalized sustainability framework for hydropower. In particular, we will outline innovative solutions for the most challenging topics of sustainable hydropower plants, including i) energy supply securing with a high share of renewable energies ii) climate change impacts on water resources and hydropower production, ii) altered flow and changed turbidity dynamics in rivers, iii) long-term downstream effects on river beds and groundwater exchange, iv) degradation of river ecology, v) socio-economic impacts on local stakeholders, vi) adequate assessment of the water-energy-food nexus, vii) near real time digitalisation framework to streamline information. Through the digitalization of the HSAP a standardized and transparent flow of information will be guaranteed. Within the presented digitalized framework, all data will be processed to standardize, harmonize and synthesize results and information from all working tasks into a data lake. We may apply this framework to demonstration hydropower plants of different types to improve their sustainability, efficiency and management

Fatigue Strength Analysis of a Prototype Francis Turbine in a Multilevel Lifetime Assessment Procedure Part II: Method Application and Numerical Investigation

Part I of the publication series addressed the fundamentals of lifetime assessment of prototype Francis turbines. This paper (Part II) focuses on the numerical part of the procedure. The essential steps and requirements shall be presented (background). The starting points for the numerical considerations are the pressure fields of the transient CFD simulations, which are exported per time step and applied to the existing structure via a fluid–structure interaction. That enables a transient mechanical stress calculation to be conducted, resulting in the fatigue analysis of the component to estimate the remaining lifetime. The individual model requirements should be represented accordingly and applied to the prototype facility (method). The results obtained from this application should be discussed and evaluated. It has to be mentioned that the validation of the numerical results will be performed at Part IV of this publication series (results). The present paper will end up discussing the results and conclusions about further data processing (Conclusion)

The new role of sustainable hydropower in flexible energy systems and its technical evolution through innovation and digitalization

Hydropower has played an important role in Europe in recent decades, offering a unique combination of safe, low-cost, and clean power generation. Today, it is still one of the largest renewable energy sources (RES), accounting for about 35 % of RES electricity generation. However, grid stability is threatened by the increasing amount of undispatchable RES. Flexibility and dynamics such as energy storage and rapid response are urgently needed to achieve EU policy goals. In such a context, hydropower can play a key role, not only as a provider of regulated renewable energy but also due to its ability to balance a renewable energy system in the short term and the medium/long term by pumped storage technology. All these aspects underline the new role of hydropower, which aims to strengthen grid stability and power supply resilience and to enable higher penetration of volatile RES. In this context, the aim of this paper is to demonstrate the role of hydropower at the European level as well as the needs and opportunities of modernization to fully exploit its potential. In particular, this study provides, the assessment of the today flexibility offered by hydropower to the power system at the European level by leveraging a database of information collected through the participants to the working groups of the COST Action Pen@Hydropower which includes stakeholders in the hydropower sector of 34 European countries. The study confirms the key role of hydropower in future energy scenarios with 30 % of the flexibility demand at all time scales met by hydropower. Furthermore, the paper presents a review of the digitalization solutions and innovative technologies that support the growth of a new generation of sustainable hydropower together with the modernization opportunities for existing hydropower plants. The results of this work have practical implications for stakeholders in the hydropower sector and policymakers as it provides evidence at the European scale of the role of hydropower technology in balancing the power system and the need to have supportive frameworks and adequate markets to fully exploit the European hydropower potential to achieve the energy transition goals

Fatigue Strength Analysis of a Prototype Francis Turbine in a Multilevel Lifetime Assessment Procedure Part I: Background, Theory and Assessment Procedure Development

Electricity generation is becoming increasingly flexible in Europe these days. Due to the integration of new renewable energy sources like wind and photovoltaic, other conventional resources, such as hydropower, operate within a brought range around their best efficiency point, thus leading to higher dynamical loads at the water-bearing parts, especially at the runner and the guide vanes (background). By scrutinizing the literature of the past years, one could summarize the outcome in that way, that research projects focused either on model measurements with higher visual accessibility or, less often, on prototype measurements in existing power plants. Today prototype measurements are performed, if possible, to eliminate scaling effects. Moreover, increasing computing power allows prototype simulations to be carried out within a reasonable time. At the acknowledged research projects, prototype and model measurements and numerical simulations have been performed to identify the main gaps in Francis turbines’ lifetime assessment (methods). One special outcome of these investigations was the impracticality of numerical simulations and calculation time, respectively, of start and stop events. Therefore, a prototype measurement with focus at this operating point should be performed to provide more data and an insight into the unit’s behavior. The future goal is a comprehensive machine unit lifetime assessment of the water-bearing parts in a Francis turbine machine set (results). This complex task needs several steps, beginning from measurements through simulations towards data processing. A particular challenge is posed, when the assessment methods are applied to old machines

Strategic Research Agenda of the EERA Joint Programme Hydropower

The launch of a new EERA Joint Programme on Hydropower is good news for energy system in Europe and beyond. The clean energy transition is necessary, demanding and accelerating. Hydropower in Europe and worldwide represents a significant tool for achieving this change sustainably. Hydropower holds capabilities for energy supply, storage, and regulation that are unique. These characteristics are needed to deliver security of supply, stability in the grid, and for green growth. Increasing the flexibility of the hydropower fleet through innovation and modernisation is fundamental for these objectives. Hydropower has a lot to offer. It can provide water management capabilities, mitigating damage from flood and drought events; it will provide clean energy and available capacity for stable and secure supplies; it will balance intermittent production from solar and wind, and it is capable of storing energy, both in short and long-term horizons. Hydropower rates very well in comparison to other renewable electricity production sources, including storage: energy-payback ratio, life-cycle assessment, greenhouse-gas emissions, water footprint, and more. Adding to that, hydropower has the highest energy-conversion efficiency and longest operating life. Without research, demonstration and investment, none of these roles will be optimised for the future. Europe is instrumental in leading the way towards decarbonisation through competence building and innovation. And the Joint Programme on hydropower represents a renewed focus on new roles and priorities for hydropower; we can no longer rely only on the mature solutions and methods; we need to bring our existing knowledge further. What happens in a power plant that shall handle thirty starts and stops each day? How can we utilise rotating mass to provide instant regulation for the system? How will power peaking affect the watercourse, and how can we integrate water management solutions together with power production, recreation and navigation? New challenges present new opportunities, but also new needs for research and innovation. The Joint Programme on Hydropower in EERA comprises a large group of excellent and dedicated R&D-communities in Europe. Our joint eff orts will be a major hub for renewed research, supporting eff orts to modernise the European fleet and assist the rest of the world, where the largest potential for new hydropower development lies. My hopes and expectations for this initiative is that it will expand globally and be a platform for research on topics related to hydropower in a world-wide perspective. The need for this initiative is clear, and everyone involved should be very proud of the launch of this platform