scholarly journals Flow Characteristics of Preliminary Shutdown and Startup Sequences for a Model Counter-Rotating Pump-Turbine

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3593
Author(s):  
Jonathan Fahlbeck ◽  
Håkan Nilsson ◽  
Saeed Salehi
Keyword(s):  
Large Scale ◽  
Reverse Flow ◽  
Renewable Energy Sources ◽  
Flow Characteristics ◽  
Head Model ◽  
Pump Turbine ◽  
Design Point ◽  
Electrical Grid ◽  
The Individual ◽  
Eu Project

Pumped Hydropower Storage (PHS) is the maturest and most economically viable technology for storing energy and regulating the electrical grid on a large scale. Due to the growing amount of intermittent renewable energy sources, the necessity of maintaining grid stability increases. Most PHS facilities today require a geographical topology with large differences in elevation. The ALPHEUS H2020 EU project has the aim to develop PHS for flat geographical topologies. The present study was concerned with the initial design of a low-head model counter-rotating pump-turbine. The machine was numerically analysed during the shutdown and startup sequences using computational fluid dynamics. The rotational speed of the individual runners was decreased from the design point to stand-still and increased back to the design point, in both pump and turbine modes. As the rotational speeds were close to zero, the flow field was chaotic, and a large flow separation occurred by the blades of the runners. Rapid load variations on the runner blades and reverse flow were encountered in pump mode as the machine lost the ability to produce head. The loads were less severe in the turbine mode sequence. Frequency analyses revealed that the blade passing frequencies and their linear combinations yielded the strongest pulsations in the system.

scholarly journals Effects of the Splitter Blade on the Performance of a Pump-Turbine in Pump Mode

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Guidong Li ◽  
Yang Wang ◽  
Puyu Cao ◽  
Jinfeng Zhang ◽  
Jieyun Mao
Keyword(s):  
Energy Storage ◽  
Large Scale ◽  
Tangential Velocity ◽  
Model Performance ◽  
Flow Characteristics ◽  
Entropy Generation Rate ◽  
Pump Mode ◽  
Pump Turbine ◽  
Blade Runner ◽  
Operation Stability

The pumped hydro energy storage is the most effective way to store large-scale electricity and has been widely used in the world. As the key equipment in the pumped hydro energy storage, it is significant and urgent to improve the performance and operation stability of the pump-turbine. In this study, the effect of runners with and without splitter blade on the performances and inner flow characteristics of a pump-turbine in pump mode was analyzed by the method of numerical calculation. The results suggest that larger tangential velocity at runner outlet and higher pressure at the trailing edge of pressure side in splitter blade runner scheme contribute to higher head. The area of backflow at runner outlet, the highest values of entropy generation rate, and vorticity distribution in splitter blade runner scheme are well smaller than those in prototype runner without splitter blade, which is conducive to improving model performance.

scholarly journals Influences of Wind Energy Integration into the Distribution Network

2013 ◽  
Vol 2013 ◽  
pp. 1-21 ◽  
Author(s):  
G. M. Shafiullah ◽  
Amanullah M. T. Oo ◽  
A. B. M. Shawkat Ali ◽  
Alex Stojcevski
Keyword(s):  
Wind Energy ◽  
High Voltage ◽  
Large Scale ◽  
Low Voltage ◽  
Renewable Energy Sources ◽  
Distribution Network ◽  
Flow Characteristics ◽  
Simulation Models ◽  
Energy Sources ◽  
Energy Integration

Wind energy is one of the most promising renewable energy sources due to its availability and climate-friendly attributes. Large-scale integration of wind energy sources creates potential technical challenges due to the intermittent nature that needs to be investigated and mitigated as part of developing a sustainable power system for the future. Therefore, this study developed simulation models to investigate the potential challenges, in particular voltage fluctuations, zone substation, and distribution transformer loading, power flow characteristics, and harmonic emissions with the integration of wind energy into both the high voltage (HV) and low voltage (LV) distribution network (DN). From model analysis, it has been clearly indicated that influences of these problems increase with the increased integration of wind energy into both the high voltage and low voltage distribution network; however, the level of adverse impacts is higher in the LV DN compared to the HV DN.

A Novel Approach to Large Scale Applications of Superconductivity: The Concept of an All Superconducting Mini Power Plant

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3717-3721
Author(s):  
Istvan Vajda
Keyword(s):  
Energy Efficient ◽  
Power Plants ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Local Power ◽  
Power Devices ◽  
Power Stations ◽  
Environmental Friendly ◽  
Novel Approach ◽  
The Individual

The widespread use of energy-efficient, environmental-friendly and secure local power stations, or mini power plants (MPPs) has become a world-wide trend. Disperse power generation has been developed against centralized generation in central power stations/plants with a particular view on the utilization of renewable energy sources. Exceeding the stage of the development of individual superconducting power devices (SPDs), more and more concern is being focused around all superconducting (AS) integrated systems (ASIS) consisting of a set of individual SPDs being integrated into one system with a common cryogenic environment. Such a system possesses with substantial additional benefits compared to and exceeding those of the individual SPDs. The concept of AS MPP model of the order of 10 kW developed by the author's team is presented in this paper.

A Study on the Characteristics of a Vortex Type Two-Step Flow-Control Device

2003 ◽  
Author(s):  
Bong-Hyun Cho ◽  
Yoon-Yeong Bae ◽  
Jong-Kyun Park
Keyword(s):  
Water Level ◽  
Flow Rate ◽  
Large Scale ◽  
Reverse Flow ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Control Device ◽  
The Core ◽  
Exit Nozzle ◽  
Control Port

The effects of major flow path geometries on the flow characteristics of a Fluidic Device (FD) have been investigated experimentally and numerically. A full-scale FD has been designed and tested to verify the required characteristics, and the geometric effects are examined by changing the internal shape of the FD. As characteristics of the FD, time dependent flow rate, flow turndown and water level change are discussed. The flow turndown ratios are in the range of about 2 to 4, and they are highly depend on the exit nozzle diameter and the control port width, but almost not affected by the chamber height. As the flow turndown ratio increases, the water level in the pipe connected to the supply port becomes unstable, and it limits the flow turndown ratio, which is 2.5 in our case. The numerically predicted flow conditions in FD were highly dependent on the turbulence models, among them the RSM model gave the most reasonable results. In a high swirl case, the difference of flow rate between the test and the numerical simulation was about 10%. As the size of exit nozzle decreases, reverse flow in the cavity of the core increases and consequently the discharge flow rate reduces. In a low swirl case, the flow field in the chamber is extremely complicated and shows transient characteristic where the flow pattern in the core shows a large-scale oscillation.

Models, Practices and Methods of Reading: Evolution in Time and Space

2009 ◽  
pp. 59-64
Author(s):  
Yulia P. Melentyeva
Keyword(s):  
Large Scale ◽  
Social Groups ◽  
National Program ◽  
Time And Space ◽  
Lack Of Information ◽  
The Individual

In recent years as public in general and specialist have been showing big interest to the matters of reading. According to discussion and launch of the “Support and Development of Reading National Program”, many Russian libraries are organizing the large-scale events like marathons, lecture cycles, bibliographic trainings etc. which should draw attention of different social groups to reading. The individual forms of attraction to reading are used much rare. To author’s mind the main reason of such an issue has to be the lack of information about forms and methods of attraction to reading.

scholarly journals Vanadium Redox Flow Batteries: A Review Oriented to Fluid-Dynamic Optimization

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 176
Author(s):  
Iñigo Aramendia ◽  
Unai Fernandez-Gamiz ◽  
Adrian Martinez-San-Vicente ◽  
Ekaitz Zulueta ◽  
Jose Manuel Lopez-Guede
Keyword(s):  
Large Scale ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Batteries ◽  
Design Flexibility ◽  
Flow Batteries ◽  
Exchange Membrane ◽  
Vanadium Redox

Large-scale energy storage systems (ESS) are nowadays growing in popularity due to the increase in the energy production by renewable energy sources, which in general have a random intermittent nature. Currently, several redox flow batteries have been presented as an alternative of the classical ESS; the scalability, design flexibility and long life cycle of the vanadium redox flow battery (VRFB) have made it to stand out. In a VRFB cell, which consists of two electrodes and an ion exchange membrane, the electrolyte flows through the electrodes where the electrochemical reactions take place. Computational Fluid Dynamics (CFD) simulations are a very powerful tool to develop feasible numerical models to enhance the performance and lifetime of VRFBs. This review aims to present and discuss the numerical models developed in this field and, particularly, to analyze different types of flow fields and patterns that can be found in the literature. The numerical studies presented in this review are a helpful tool to evaluate several key parameters important to optimize the energy systems based on redox flow technologies.

scholarly journals Sizing and Management of Energy Storage Systems in Large-Scale Power Plants Using Price Control and Artificial Intelligence

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3296
Author(s):  
Carlos García-Santacruz ◽  
Luis Galván ◽  
Juan M. Carrasco ◽  
Eduardo Galván
Keyword(s):  
Energy Storage ◽  
Power Plants ◽  
Large Scale ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Ancillary Services ◽  
Energy Sources ◽  
Energy Storage Systems ◽  
Electric System ◽  
Fundamental Part

Energy storage systems are expected to play a fundamental part in the integration of increasing renewable energy sources into the electric system. They are already used in power plants for different purposes, such as absorbing the effect of intermittent energy sources or providing ancillary services. For this reason, it is imperative to research managing and sizing methods that make power plants with storage viable and profitable projects. In this paper, a managing method is presented, where particle swarm optimisation is used to reach maximum profits. This method is compared to expert systems, proving that the former achieves better results, while respecting similar rules. The paper further presents a sizing method which uses the previous one to make the power plant as profitable as possible. Finally, both methods are tested through simulations to show their potential.

scholarly journals Lighting System Modernization as a Source of Green Energy

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2771
Author(s):  
Leszek Kotulski ◽  
Artur Basiura ◽  
Igor Wojnicki ◽  
Sebastian Siuchta
Keyword(s):  
Renewable Energy ◽  
Urban Areas ◽  
Large Scale ◽  
Energy Savings ◽  
Renewable Energy Sources ◽  
Green Energy ◽  
Light Sources ◽  
Levelized Cost Of Electricity ◽  
Cost Of Electricity ◽  
Lighting Retrofit

The use of formal methods and artificial intelligence has made it possible to automatically design outdoor lighting. Quick design for large cities, in a matter of hours instead of weeks, and analysis of various optimization criteria enables to save energy and tune profit stream from lighting retrofit. Since outdoor lighting is of a large scale, having luminaires on every street in urban areas, and since it needs to be retrofitted every 10 to 15 years, choosing proper parameters and light sources leads to significant energy savings. This paper presents the concept and calculations of Levelized Cost of Electricity for outdoor lighting retrofit. It is understood as cost of energy savings, it is in the range from 23.06 to 54.64 EUR/MWh, based on real-world cases. This makes street and road lighting modernization process the best green “energy source” if compared with the 2018 Fraunhofer Institute cost of electricity renewable energy technologies ranking. This indicates that investment in lighting retrofit is more economically and ecologically viable than investment in new renewable energy sources.

scholarly journals Modelling Stochastic Electricity Demand of Electric Vehicles Based on Traffic Surveys—The Case of Austria

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1577
Author(s):  
Albert Hiesl ◽  
Jasmine Ramsebner ◽  
Reinhard Haas
Keyword(s):  
Electric Vehicles ◽  
Renewable Energy Sources ◽  
Length Distribution ◽  
Electricity Demand ◽  
Transport Sector ◽  
Trip Purpose ◽  
Entire Country ◽  
Electricity Load ◽  
The Individual ◽  
Model Based Analysis

Battery-powered electric mobility is currently the most promising technology for the decarbonisation of the transport sector, alongside hydrogen-powered vehicles, provided that the electricity used comes 100% from renewable energy sources. To estimate its electricity demand both nationwide and in individual smaller communities, a calculation based assessment on driving profiles that are as realistic as possible is required. The developed model based analysis presented in this paper for the creation of driving and thus electricity load profiles makes it possible to build different compositions of driving profiles. The focus of this paper lies in the analysis of motorised private transport, which makes it possible to assess future charging and load control potentials in a subsequent analysis. We outline the differences in demand and driving profiles for weekdays as well as for Saturdays, Sundays and holidays in general. Furthermore, the modelling considers the length distribution of the individual trips per trip purpose and different start times. The developed method allows to create individual driving and electric vehicle (EV) demand profiles as well as averaged driving profiles, which can then be scaled up and analysed for an entire country.

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