In this paper we assessed changes in scaling properties of the river Danube level and flow data, associated with building of Djerdap/Iron Gates hydrological power plants positioned on the border of ...Romania and Serbia. We used detrended fluctuation analysis (DFA), wavelet transform spectral analysis (WTS) and wavelet modulus maxima method (WTMM) to investigate time series of measurements from hydrological stations in the vicinity of dams and in the area of up to 480 km upstream from dams, and time series of simulated NOAA-CIRES 20th Century Global Reanalysis precipitation data for the Djerdap/Iron Gates region. By comparing river dynamics during the periods before and after construction of dams, we were able to register changes in scaling that are different for recordings from upstream and from downstream (from dams) areas. We found that damming caused appearance of human-made or enhancement of natural cycles in the small time scales region, which largely influenced the change in temporal scaling in downstream recording stations. We additionally found disappearance or decline in the amplitude of large-time-scale cycles as a result of damming, which changed the dynamics of upstream data. The most prominent finding of our paper is a demonstration of a complete or partial loss of annual cycles in the upstream stations’ data that stems from the operation of the artificial water reservoir and extends as far as 220 km from dams. We discussed probable sources of such found changes in scaling, aiming to provide explanations that could be of use in future environmental assessments.
•Scaling analysis was used to assess effects of damming on river dynamics.•It is shown that the upstream annual river level cycle is lost after damming.•The observed changes in natural cycles may serve as guides for hydro power planning.
Owing to slowly lessening of fossil fuel, economical use of obtainable fuel for electric power and heat generation has turn out to be an important worry of utility industries. In this manuscript, ...fuel constrained combined heat and power unit commitment incorporating renewable energy sources and electric vehicle parking lot is undertaken for addressing the optimum generation scheduling of the committed units. Here thermal generating units (TGUs), cogeneration units (CGUs), heat only units (HOUs), cascaded hydro power plants (CHPPs) and solar PV plants (SPVPs) and wind turbine generators (WTGs) are considered. A number of plug-in electric vehicles (PEVs) with charging and discharging behaviours is also considered. The problem is solved with and without fuel constraints. The UC problem is solved by using binary differential evolution (BDE) along with priority list (PL). Numerical results of the test systems are included to provide valued minutiae for operational and planning problems.
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•Fuel constrained combined heat and power commitment scheduling has been studied.•Cascaded hydro power plants, solar PV plants, wind turbine generators are considered.•50 000 PEVs have been incorporated with both G2V mode and G2V/V2G modes.
The paper deals with a unit commitment problem of a generation company whose aim is to find the optimal scheduling of a multiunit pump-storage hydro power station, for a short term period in which ...the electricity prices are forecasted. The problem has a mixed-integer nonlinear structure, which makes very hard to handle the corresponding mathematical models. However, modern mixed-integer linear programming (MILP) software tools have reached a high efficiency, both in terms of solution accuracy and computing time. Hence we introduce MILP models of increasing complexity, which allow to accurately represent most of the hydroelectric system characteristics, and turn out to be computationally solvable. In particular we present a model that takes into account the head effects on power production through an enhanced linearization technique, and turns out to be more general and efficient than those available in the literature. The practical behavior of the models is analyzed through computational experiments on real-world data.
The importance of renewable energy will increase rapidly due to the global regulation of carbon dioxide emissions to cope with global warming. However, renewable energy has a high output variation ...because of the fluctuating characteristics of the energy source. Therefore, pumped-storage power stations require high flexibility and reliability in operation under off-design conditions, especially in the pump mode. When a pump-turbine operates under various part load conditions in pump mode, highly dynamic phenomenon such as stationary vortex and rotating stall occur. The performance characteristics in pump mode are vital for the safe and effective operation. A number of studies have been conducted to investigate the flow characteristics in a turbine or pump mode under different GVOs through numerical simulations. However, the studies about the influence of the position of the interface and the steady and unsteady interface condition on the pump characteristics of pump-turbines have been not completely clear. In this paper, the three-dimensional steady and unsteady Reynolds-averaged Navier–Stokes equations were solved for a detailed analysis of the influence of interface conditions with various guide vane opening conditions in pump mode. To ensure the reliability of the numerical analysis, the numerical results were validated in comparison with the experimental data.
•The effect of interface conditions with various guide vane openings was studied.•The numerical results were validated in comparison to the experimental data.•The dynamic flow phenomenon and hysteresis characteristics were investigated.•The location and magnitude of vortex under the hump region were observed.•The unsteady pressure characteristics were analyzed with internal flow field.
Neubau Bahnstromkraftwerk Obervellach II Höss, Christian; Binder, Michael; Hofmann, Michael ...
Geomechanik und Tunnelbau,
10/2022, Letnik:
15, Številka:
5
Journal Article
Recenzirano
Abstract
In the interests of climate protection, ÖBB Infrastruktur AG traditionally focuses on the sustainable use of hydro‐electric power for the generation of traction current for the railways. ...After about 100 years in service, the existing Obervellach I and Lassach power stations will be replaced by the more efficient new Obervellach II and Kaponig plants. With an increased output of 38 MW and a regular working capacity of 125 GWh per year, around 30,000 high speed journeys from Villach to Vienna will be possible.
The challenges in the course of the submission, tender and project planning were the complexity of the project and its size. In particular, the hydraulic, geographical, geological and ecological conditions required cross‐disciplinary cooperation in all phases of the planning. Likewise, close coordination between the contractor and the local construction supervision took place and continues to take place in the course of the project.
The vastness of the project area requires sophisticated logistics in its execution. The tunnelling work, in particular, was challenging due to the small cross‐section to be excavated and the tunnel length. A special feature is the use of a full‐round formwork carriage. During the work along the high pressure down pipe in impassable terrain, using a cableway for carrying material, the focus is on the parallel health and safety arrangements in the construction and equipment activities. The whole project is planned to be commissioned in March 2024.
Abstract
Im Sinne des Klimaschutzes setzt die ÖBB Infrastruktur AG traditionell auf die nachhaltige Nutzung der Wasserkraft für die Bahnstromerzeugung. Nach ca. 100 Jahren Laufzeit werden die Bestandskraftwerke Obervellach I und Lassach durch die effizienteren Neuanlagen Obervellach II und Kaponig ersetzt. Mit der Ausbauleistung von 38 MW und einem Regelarbeitsvermögen von 125 GWh pro Jahr werden rund 30.000 Railjetfahrten von Villach nach Wien ermöglicht. Die planerischen Herausforderungen im Zuge der Einreichungs‐, Ausschreibungs‐ und Ausführungsplanung lagen in der Komplexität des Gesamtprojekts. Vor allem die hydraulischen, geographischen, geologischen und ökologischen Rahmenbedingungen erforderten von allen Beteiligten eine fachübergreifende Zusammenarbeit in allen Planungsphasen. Ebenso fanden und finden im Zuge der Ausführung intensive Abstimmungen mit dem Auftragnehmer und der örtlichen Bauaufsicht statt. Die Weitläufigkeit des Projektgebiets erfordert in der Ausführung eine ausgeklügelte Logistik. Speziell die Vortriebsarbeiten waren aufgrund des kleinen Ausbruchquerschnitts sowie der Stollenlänge herausfordernd. Als Besonderheit gilt der Einsatz eines Full‐Round Schalwagens. Bei den Arbeiten entlang des Kraftabstiegs im unwegsamen Gelände stehen, mit Unterstützung einer Materialseilbahn, die parallelen Bau‐ und Ausrüstungstätigkeiten hinsichtlich Arbeitssicherheit im Fokus. Die Gesamtinbetriebnahme ist für März 2024 geplant.
This paper addresses the problem of designing an optimal micro-hydro power installation in rivers with generic profiles, when micro-hydro schemes are studied. This is geared towards the application ...of Micro-Hydro Power Plants to supply marginal isolated areas using small Pelton wheels, where both technology and resources are limited. For this purpose, a model of a Pelton micro-hydro plant is first developed. Subsequently, a discretization of the river profile is made, on the basis of which a set of integer variables are proposed, being the model transformed then into an integer optimization problem. Finally, the effectiveness of the proposed method is showed through a specific design problem. The application of the developed method is especially interesting when designing micro-hydro plants to provide electricity to isolated populations, where both technology and resources are limited.
•The paper proposes a design methodology to optimize Micro-Hydro Power Plants.•Models of the obtainable power, the problem geometry, and the installation cost are developed.•The resulting optimization problem is casted as an integer optimization problem.•A simulated case study shows the main characteristics of the design method.•A friendly graphic user interface has been programmed.
The aim of the present paper is to investigate the use of the site “Potamon” Dam in the Prefecture of Rethymnon, Crete island, Greece, as a “virtual” renewable electricity supply of a pumped storage ...plant (PSP) in order to save and exploit the maximum possible part of the rejected wind energy of the autonomous power system of the Crete island. Taking into account the annual time series of the rejected power of the Crete power grid, the present research work targets the optimal configuration of the proposed PSP power station, including the sizing of its individual components as well as the determination of the capacity it could guarantee in order to be economically viable. The rejected electric energy from the actually operating wind farm production, which is not possible to be absorbed by the grid of Crete due to its stable operation limitations, could be absorbed by the here proposed pump storage plant (PSP) and converted to hydraulic energy. This can be achieved by pumping the water from the lower reservoir, which is the existing reservoir of the site “Potamon” Dam, with a storage capacity of about 22.5 million m3, up to the upper reservoir, which must be constructed accordingly. For the proposed PSP’s optimal size determination, established financial indices are used as an evaluation criterion for an investment life cycle of 25 years. The proposed PSP optimization is based on the dynamic mathematical model of the simulation results of the PSP’s hourly operation when incorporated in the Crete power grid for a whole year, performed in the Matlab 2016b computational environment (The MathWorks, Inc., Natick, MA, USA). The results of this research demonstrate the PSP’s technical feasibility and determine the PSP’s optimal CAPEX and the PSP’s whole life-time financial indicators in order that the whole investment be viable. Furthermore, the appropriate selling prices of the electricity produced from the proposed PSP were determined to achieve the PSP’s financial viability. The results comprise the key elements to prove the necessity for the establishment a.s.a.p. of the appropriate legal framework in order to have authorization to exploit the rejected RES (renewable energy sources) electric energy or the major part of it through PSPs, in priority in both the non-interconnected, as well as the interconnected power systems.
Abstract
Claim‐ and anti‐claim‐management is becoming increasingly important on construction sites. More and more (human) resources from contractor and owner are being invested in projects for this ...purpose. This is clearly counterproductive for the success of the project, since claim and anti‐claim‐management do not create any added value in the project and the actual target of a construction project is pushed into the background. In this article, the differences between plannable and dynamic‐complex systems are used to show, where classic construction contract models reach their limits and which projects are better implemented with alternative contracts. Based on the Alliance Contract for the successfully completed project „Triebwasserweg Maria Stein”, it is shown why Alliance Contracts are more suitable than classic contract models for dynamic‐complex (risky) large‐scale projects, such as large tunnel projects in difficult geology. By choosing the right contract model for the project, the best project results can be achieved, and legal disputes can be avoided even in crisis situations.
Abstract
Claim‐ und Anti‐Claim‐Management gewinnt auf Baustellen immer mehr an Bedeutung. Sowohl auf Auftragnehmer‐ als auch auf Auftraggeberseite werden dafür in den Projekten immer mehr (personelle) Ressourcen investiert. Für den Projekterfolg ist dies klarerweise kontraproduktiv, da durch Claim‐ und Anti‐Claim‐Management kein Mehrwert im Projekt geschaffen wird und das eigentliche Ziel eines Bauprojekts in den Hintergrund rückt. Im gegenständlichen Beitrag wird anhand der Unterschiede zwischen planbaren und dynamisch‐komplexen Systemen aufgezeigt, wo klassische Bauvertragsmodelle an ihre Grenzen stoßen und welche Projekte besser mit alternativen Vertragsmodellen umgesetzt werden sollten. Anhand des Allianzvertrags für das bereits abgeschlossene Projekt Triebwasserweg Maria Stein wird dargestellt, warum Allianzverträge für dynamisch‐komplexe (risikobehaftete) Großprojekte, z. B. große Tunnelprojekte in schwieriger Geologie, besser geeignet sind als klassische Vertragsmodelle. Durch die Wahl des richtigen Vertragsmodells für das Projekt können die besten Projektergebnisse erzielt und Rechtsstreitigkeiten auch in Krisensituationen vermieden werden.
PSP (Pumped-storage power plants) represent the only mature option for large-scale electricity storage, and offer a wide range of grid management services, ranging from peak power production to ...ancillary services. This technology has undergone drastic progress in reliability, efficiency and generation capacity, with modern PSP being able to switch from pumping to generating mode in a few minutes and working at different levels of part load. This article presents a historical perspective and the current trends in PSP deployment at a global level. It covers initial investment rationale, the evolution of the operational management and trends in installed capacities, and a systematic overview on the contribution of PSP to electricity system flexibility and reliability to different electricity markets and different power grid configurations. Particular attention is devoted to the electricity production mix evolution in the selected countries. The role and operation of PSP have evolved significantly over time to adapt to new electricity mix and market conditions. Insights regarding the prospects and barriers of PSP in the coming decades are discussed, and estimates of remaining potential are compared with future storage needs, highlighting that alternative energy storage technologies will need to emerge alongside PSP to meet the future needs.
•Complete review of pumped storage plants globally and in some chosen countries.•Drivers behind the construction of pumped-storage power plants.•Evolution of the usage of pumped-storage power plants over time.•Comparison between regions (China, Japan, USA and Europe).
Neubau des Pumpspeicherwerks Forbach Stech, Hans‐Joachim; Achatz, Robert; Strasser, Peter ...
Geomechanik und Tunnelbau,
10/2022, Letnik:
15, Številka:
5
Journal Article
Recenzirano
Abstract
The Rudolf‐Fettweis hydropower plant, owned and operated by EnBW Energie Baden‐Württemberg AG, is situated in the Murg valley in the Northern Black Forest. The construction of a new ...underground Lower Basin is planned to upgrade the existing hydropower station. The in‐situ rock mass consists of Forbach Granite with local weakness zones, as encountered in the boreholes. Considering the extent of the project area, a 3D geological prediction model was used to allow a better interpretation of the spatial relationships of weakness zones in the rock mass and to optimize the orientation of the underground caverns. Adverse effects for the public were counteracted at a very early stage, so that the project received a high level of public acceptance. The present paper describes the current state of the project.
Abstract
Im Murgtal im Nordschwarzwald befindet sich das Rudolf‐Fettweis‐Werk der EnBW Energie Baden‐Württemberg AG. Zur Erneuerung des Standorts ist der Neubau einer untertägigen Unterstufe geplant. Die im Projekt angetroffenen geologischen Verhältnisse bestehen aus der Formation des Forbach‐Granits, in dem lokale Schwächezonen erkundet wurden. Angesicht der Ausdehnung des Projektgebiets kam ein 3D‐Prognosemodell der Geologie zum Einsatz, um die Interpretation der räumlichen Lagebeziehung der Schwächezonen im Gebirge und die Orientierungen der neuen unterirdischen Anlagen entsprechend zu optimieren. Der Vermeidung öffentlicher Betroffenheiten wurde frühzeitig entgegengewirkt, sodass das Projekt eine ausgesprochen hohe Akzeptanz in der Öffentlichkeit genießt. Der vorliegende Beitrag stellt den aktuellen Stand im Projekt vor.
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