Introducing plausible mega-droughts in hydropower scheduling at the power grid level

2020 ◽  
Author(s):  
Marcelo Olivares ◽  
Eduardo Pereira ◽  
Fernanda Abarzua ◽  
Matias Gomez ◽  
Diana Orellana
Keyword(s):  
Power Plants ◽  
Planning Horizon ◽  
Hydropower Plant ◽  
Scenario Tree ◽  
Climate Projections ◽  
Severe Drought ◽  
Value Functions ◽  
Medium Term ◽  
Spatial Correlation Structure ◽  
Wide Range

<p>Hydropower operations are commonly prescribed as part of a grid-wide coordination process by an Independent System Operator (ISO). The scheduling problem is usually divided into two coupled problems: short- and medium-term scheduling. The medium term problem, usually within a planning horizon of a few years, takes into account uncertain inflows to every hydropower plant in the grid. This uncertainty is often represented by a scenario tree constructed from historical records. The result of this stochastic optimization problem is a set of Future Value Functions (FVF) of water in the reservoirs. These functions represent the carryover storage value, as avoided future thermal costs, for each week within the planning horizon. These FVFs are then used as a boundary condition for short-term scheduling within each week.</p><p>Chile has suffered a 10-year severe drought since 2010. Moreover, climate projections for Chile suggest an intensification of droughts in the future, in terms of both frequency and magnitude. From the water-energy nexus perspective, this phenomenon would rise energy costs and prices, and at the same time, push the electric coordinator to feed the system with less clean sources of electricity.</p><p>This work proposes and tests alternative ways to introduce plausible mega-droughts in Chile as part of the power scheduling process. We develop series representing plausible future conditions of drought and severe drought, preserving the time and spatial correlation structure of inflows. These scenarios are then used, along with historical information, to develop FVFs that take into account those severe drought scenarios. The method is tested in Chile’s main grid, represented by 624 power plants, 103 inflow points, 13 reservoirs, and 58 demand nodes.</p><p>The FVFs obtained from each alternative approach are then simulated under a wide range of futures. Results show that the introducing very severe droughts is not the best course of action, as the corresponding FVFs perform very poorly under moderately dry futures. In contrast, introducing scenarios with a moderate dry bias performs better over a wide range of future conditions, except for extremely severe droughts.   </p>

scholarly journals MOSAIK and FMI-Based Co-Simulation Applied to Transient Stability Analysis of Grid-Forming Converter Modulated Wind Power Plants

2021 ◽  
Vol 11 (5) ◽  
pp. 2410
Author(s):  
Nakisa Farrokhseresht ◽  
Arjen A. van der Meer ◽  
José Rueda Torres ◽  
Mart A. M. M. van der Meijden
Keyword(s):  
Power System ◽  
Time Domain ◽  
Power Plants ◽  
Transient Stability ◽  
Renewable Energy Sources ◽  
Critical Factor ◽  
Primary Control ◽  
Simulation Approach ◽  
Wide Range ◽  
Grid Side

The grid integration of renewable energy sources interfaced through power electronic converters is undergoing a significant acceleration to meet environmental and political targets. The rapid deployment of converters brings new challenges in ensuring robustness, transient stability, among others. In order to enhance transient stability, transmission system operators established network grid code requirements for converter-based generators to support the primary control task during faults. A critical factor in terms of implementing grid codes is the control strategy of the grid-side converters. Grid-forming converters are a promising solution which could perform properly in a weak-grid condition as well as in an islanded operation. In order to ensure grid code compliance, a wide range of transient stability studies is required. Time-domain simulations are common practice for that purpose. However, performing traditional monolithic time domain simulations (single solver, single domain) on a converter-dominated power system is a very complex and computationally intensive task. In this paper, a co-simulation approach using the mosaik framework is applied on a power system with grid-forming converters. A validation workflow is proposed to verify the co-simulation framework. The results of comprehensive simulation studies show a proof of concept for the applicability of this co-simulation approach to evaluate the transient stability of a dominant grid-forming converter-based power system.

scholarly journals Development of a Hydropower Turbine Using Seawater from a Fish Farm

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 266
Author(s):  
Md Rakibuzzaman ◽  
Sang-Ho Suh ◽  
Hyoung-Ho Kim ◽  
Youngtae Ryu ◽  
Kyung Yup Kim
Keyword(s):  
Power Plants ◽  
Guide Vane ◽  
Cross Flow ◽  
Synchronous Generator ◽  
Fish Farm ◽  
Hydropower Plant ◽  
Fish Farms ◽  
Data Simulation ◽  
Small Hydropower ◽  
Hydropower Plants

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

Analysis of Thick-Walled Pipeline Elements Operating in Creep Conditions

2015 ◽  
Vol 712 ◽  
pp. 63-68
Author(s):  
Przemysław Osocha ◽  
Bohdan Węglowski
Keyword(s):  
Finite Element ◽  
Test Data ◽  
Creep Test ◽  
Power Plants ◽  
Steam Pressure ◽  
Creep Model ◽  
Creep Process ◽  
Fe Model ◽  
Element Analysis ◽  
Wide Range

In some coal-fired power plants, pipeline elements have worked for over 200 000 hours and increased number of failures is observed. The paper discuses thermal wear processes that take place in those elements and lead to rupture. Mathematical model based on creep test data, and describing creep processes for analyzed material, has been developed. Model has been verified for pipeline operating temperature, lower than tests temperature, basing on Larson-Miller relation. Prepared model has been used for thermal-strength calculations based on a finite element method. Processes taking place inside of element and leading to its failure has been described. Than, basing on prepared mathematical creep model and FE model introduced to Ansys program further researches are made. Analysis of dimensions and shape of pipe junction and its influence on operational element lifetime is presented. In the end multi variable dependence of temperature, steam pressure and element geometry is shown, allowing optimization of process parameters in function of required operational time or maximization of steam parameters. The article presents wide range of methods. The creep test data were recalculated for operational temperature using Larson-Miller parameter. The creep strain were modelled, used equations and their parameters are presented. Analysis of errors were conducted. Geometry of failing pipe junction was introduced to the Ansys program and the finite element analysis of creep process were conducted.

Crack Growth Prediction and Leakage Potential of Steam Generator Tubes Subjected to Flow Induced Vibrations

2014 ◽  
Author(s):  
Salim El Bouzidi ◽  
Marwan Hassan ◽  
Jovica Riznic
Keyword(s):  
Crack Growth ◽  
Steam Generator ◽  
Power Plants ◽  
Mechanical Energy ◽  
Steam Generators ◽  
Two Phase ◽  
Element Analysis ◽  
Wide Range ◽  
Flow Induced Vibrations ◽  
Crack Growth Model

Nuclear steam generators are critical components of nuclear power plants. Flow-Induced Vibrations (FIV) are a major threat to the operation of nuclear steam generators. The two main manifestations of FIV in heat exchangers are turbulence and fluidelastic instability, which would add mechanical energy to the system resulting in great levels of vibrations. The consequences on the operation of steam generators are premature wear of the tubes, as well as development of cracks that may leak radioactive heavy water. This paper investigates the effect of tube support clearance on crack propagation. A crack growth model is used to simulate the growth of Surface Flaws and Through-Wall Cracks of various initial sizes due to a wide range of support clearances. Leakage rates are predicted using a two-phase flow leakage model. Non-linear finite element analysis is used to simulate a full U-bend subjected to fluidelastic and turbulence forces. Monte Carlo Simulations are then used to conduct a probabilistic assessment of steam generator life due to crack development.

scholarly journals The influence of water resources on transformation of spatial-functional structure of the territory of the municipality of Mali Zvornik and the possibilities for the construction of new hydro power plants

2010 ◽  
Vol 90 (3) ◽  
pp. 189-206 ◽  
Author(s):  
Mila Pavlovic ◽  
Rajko Golic ◽  
Dejan Sabic
Keyword(s):  
Water Resources ◽  
Power Plants ◽  
Hydraulic Engineering ◽  
Functional Structure ◽  
Hydropower Plant ◽  
Small Scale ◽  
Hydro Power ◽  
Hydropower Plants ◽  
Economic Revitalization ◽  
Hydro Power Plants

The territory of the municipality of Mali Zvornik is, from the aspect of morphology and spatial-functional structure, a heterogeneous area. It is located in the valley of the Drina River and in hilly-mountainous part of Podrinjske mountains. The area of the municipality is 184 km?, with 14076 inhabitants (2002). The importance of water resources for the development of the municipality, particularly of the hydropower plant (HPP) ?Zvornik?, is analyzed in this paper. Inadequate use of hydro-energetic potential, possibilities for construction of new hydropower plants and economic reasons for their construction are also emphasized. The priorities of the development of hydraulic engineering are defined in relation to morphological and hydrological conditions. They refer to increase of power of the HPP ?Zvornik? and construction of small-scale hydropower plants in hilly-mountainous part of municipality. Considering depopulation processes in the villages of Mali Zvornik, hydraulic engineering, together with agriculture, forestry, exploitation of mineral goods and tourism, can be one of the factors of demographic and economic revitalization of this area.

scholarly journals Modeling of advanced fossil fuel power plants

2021 ◽  
Author(s):  
Farshid Zabihian
Keyword(s):  
Power Generation ◽  
Gas Turbine ◽  
Power Plants ◽  
Fossil Fuel ◽  
Specific Power ◽  
Operating Pressure ◽  
Utilization Factor ◽  
Fuel Switching ◽  
Wide Range ◽  
Cycle Efficiency

The first part of this thesis deals with greenhouse gas (GHG) emissions from fossil fuel-fired power stations. The GHG emission estimation from fossil fuel power generation industry signifies that emissions from this industry can be significantly reduced by fuel switching and adaption of advanced power generation technologies. In the second part of the thesis, steady-state models of some of the advanced fossil fuel power generation technologies are presented. The impacts of various parameters on the solid oxide fuel cell (SOFC) overpotentials and outputs are investigated. The detail analyses of operation of the hybrid SOFC-gas turbine (GT) cycle when fuelled with methane and syngas demonstrate that the efficiencies of the cycles with and without anode exhaust recirculation are close, but the specific power of the former is much higher. The parametric analysis of the performance of the hybrid SOFC-GT cycle indicates that increasing the system operating pressure and SOFC operating temperature and fuel utilization factor improves cycle efficiency, but the effects of the increasing SOFC current density and turbine inlet temperature are not favourable. The analysis of the operation of the system when fuelled with a wide range of fuel types demonstrates that the hybrid SOFC-GT cycle efficiency can be between 59% and 75%, depending on the inlet fuel type. Then, the system performance is investigated when methane as a reference fuel is replaced with various species that can be found in the fuel, i.e., H₂, CO₂, CO, and N₂. The results point out that influence of various species can be significant and different for each case. The experimental and numerical analyses of a biodiesel fuelled micro gas turbine indicate that fuel switching from petrodiesel to biodiesel can influence operational parameters of the system. The modeling results of gas turbine-based power plants signify that relatively simple models can predict plant performance with acceptable accuracy. The unique feature of these models is that they are developed based on similar assumptions and run at similar conditions; therefore, their results can be compared. This work demonstrates that, although utilization of fossil fuels for power generation is inevitable, at least in the short- and mid-term future, it is possible and practical to carry out such utilization more efficiently and in an environmentally friendlier manner.

scholarly journals Operational and financial performance of fossil fuel power plants within a high renewable energy mix

2017 ◽  
Vol 1 ◽  
pp. 2BIOTO ◽  
Author(s):  
Patrick Eser ◽  
Ndaona Chokani ◽  
Reza S. Abhari
Keyword(s):  
Renewable Energy ◽  
Financial Performance ◽  
Electricity Markets ◽  
Power Plants ◽  
Energy System ◽  
Renewable Power ◽  
High Penetration ◽  
Demand Models ◽  
Wide Range ◽  
Coal Power Plants

AbstractThe operation of conventional power plants in the 2030 high-renewable energy system of central Europe with high penetration of renewables is simulated in this work. Novel insights are gained in this work, since the generation, transmission and demand models have high geographic resolution, down to scale of individual units, with hourly temporal resolution. It is shown that the increases in the partload efficiency that optimize gas power plants’ financial performance in 2030 are highly dependent on the variability in power production of renewable power plants that are in close proximity to the gas power plants. While coal power plants are also cycled more, an increased baseload efficiency is more beneficial for their financial viability. Thus, there is a need for OEMs to offer a wide range of technology solutions to cover all customers’ needs in electricity markets with high penetrations of renewables. Therefore there is an increased investment risk for OEMs as they strive to match their customers’ future needs.

scholarly journals Coal Mine Methane Utilization in Gas Turbine Units for Electricity and Heat Production

2015 ◽  
Vol 4 (5) ◽  
pp. 41-48 ◽  
Author(s):  
Кулаков ◽  
D. Kulakov ◽  
Щёголев ◽  
N. Shchegolev ◽  
Тумашев ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Coal Mining ◽  
Coal Mine ◽  
Power Plants ◽  
Negative Impact ◽  
Inlet Temperature ◽  
Ecological Situation ◽  
Modern Approach ◽  
Coal Mine Methane ◽  
Wide Range

Coal mining is accompanied by the release of coal mine methane. Its emissions into the atmosphere within methane-air mixture have a negative impact on the ecological situation. The modern approach involves the use of methane-air-mixture for heat boilers or units to generate electricity. For the generation of heat and electrical energy the coal mine methane could be used in cogeneration gas turbine plants with an altered sequence of processes. Thermo — and gas dynamics studies were conducted in a wide range of parameters of gas turbine plants. For small power plants recommended are: 2.8 compression ratio, turbine inlet — 1173 K, gas cooler inlet temperature — 303 K, 0.8 regeneration ratio. In this case the electrical efficiency of gas turbine plant is 25–26% and even 63–64% if produced heat is counted. Cogeneration gas turbine plant with an altered sequence of process has smaller capital and operating costs compared to traditional gas turbine unit. The use of methane-air mixture as fuel in such gas turbine units increases the profitability of coal mining and improves the ecological situation in the region.

A State-of-the-Art CFD Setup for Axial Compressors: Details and Validation

2020 ◽  
Author(s):  
Lorenzo Cozzi ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Savino Depalo ◽  
Pio Astrua ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
State Of The Art ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Cfd Modelling ◽  
Axial Compressors ◽  
Surge Margin ◽  
Wide Range

Abstract The overall fraction of the power produced by renewable sources in the energy market has significantly increased in recent years. The power output of most of these clean sources is intrinsically variable. At present day and most likely in the upcoming future, due to the lack of inexpensive and reliable large energy storage systems, conventional power plants burning fossil fuels will still be part of the energy horizon. In particular, power generators able to promptly support the grid stability, such as gas turbines, will retain a strategic role. This new energy scenario is pushing gas turbine producers to improve the flexibility of their turbomachines, increasing the need for reliable numerical tools adopted to design and validate the new products also in operating conditions far from the nominal one. Especially when dealing with axial compressors, i.e. machines experiencing intense adverse pressure gradients, complex flow structures and severe secondary flows, CFD modelling of offdesign operation can be a real challenge. In this work, a state-of-the art CFD framework for RANS analysis of axial compressors is presented. The various aspects involved in the whole setup are discussed, including boundary conditions, meshing strategies, mixing planes modelling, tip clearance treatment, shroud leakages and turbulence modelling. Some experiences about the choice of these aspects are provided, derived from a long-date practice on this kind of turbomachines. Numerical results are reported for different full-scale compressors of the Ansaldo Energia fleet, covering a wide range of operating conditions. Furthermore, details about the capability of the setup to predict compressor performance and surge-margin have been added to the work. In particular, the setup surge-margin prediction has been evaluated in an operating condition in which the turbomachine experiences experimental stall. Finally, thanks to several on-field data available at different corrected speeds for operating conditions ranging from minimum to full load, a comprehensive validation of the presented numerical framework is also included in the paper.

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