Turbine Power Generation Research Articles

Impact of nozzle pressure ratio and convergent-divergent length on the exit Mach number of supersonic jet

Purpose The purpose of the study is to find the effect of convergent and divergent section length on the exit flow characteristics. Converging-diverging (CD) nozzle design can be difficult because of the necessity for precise geometry and an understanding of compressible fluid flow dynamics. To obtain the ideal supersonic speeds, it is challenging to make sure that the flow chokes at the throat, where the Mach number approaches one and then expands appropriately in the diverging region. The design needs to take into consideration things like the relationship between the area and Mach number, the impact of various pressure ratios and the flow’s isentropic interactions. Design/methodology/approach An ideal thrust production is achieved through the effective acceleration of exhaust gases through proper nozzle design. This paper numerically investigates impact of convergent, divergent length and nozzle pressure ratio on the exit Mach Number of CD nozzle supersonic jet. Exit Mach Number 1.6 convergent-divergent nozzle was used. In total, five cases were taken as the length of the both the convergent-divergent sections were modified with 50% of increment and decrement in its base length. At four different NPR, the analysis was carried out in over-expanded, correctly expanded and under-expanded conditions. The NPR used were 2, 3.2, 4 and 5. Findings From the results, it is found that the convergent length linearly affects the exit Mach number, while the divergent length variation is not in order. Both the decreased and increased divergent length reduce the supersonic jet exit Mach number. The subsonic region is not majorly affected by the length. There is no rapid change in the flow properties whether the length is reduced or increased. Maximum of 2% to 3% variation is only noticed. On the contrary, a small change in supersonic region or divergent section makes major modification in the flow. Originality/value To achieve the desired Mach number, not only the area of the nozzle but also the length affects it. In terms of divergent angle and area ratio, only most of the studies on nozzle have been focused. This study aims to find the impact of convergent length and divergent length on the exit Mach number. This could be used in a wide range of applications, including laser cutting, thermal spraying, gas turbines for power generation, rocket and jet engines, supersonic wind tunnels and turbo chargers in automotive engineering, because of their capacity to accelerate fluids to supersonic speeds.

Numerical Comparison of Three Rotors For Gravitational Water Vortex Turbine

Renewable energy sources have gained significant attention due to the increasing demand for clean energy production. The gravitational vortex turbine (GVT) is one of the emerging technologies in the field of renewable energy that has gained attention for its simple and low-cost manufacturing process. The turbine operates by utilizing the energy of wastewater or other liquid flows to generate power on-site, making it a potentially viable solution for small-scale power generation. However, the optimization of the turbine's design is necessary to improve its efficiency and to make it a more competitive source of renewable energy. Previous research on GVT has mainly focused on the chamber's design to improve the formation of the vortex. However, little attention has been paid to the rotor design, which is also a critical parameter affecting the turbine's performance. The current study aimed to investigate the performance of three different rotors for the turbine, including the Savonius, H-Darrieus, and a standard rotor with straight blades, using numerical simulations. The numerical simulations were performed using ANSYS software, with ICEM modules for discretization and CFX for simulation. The results showed that the straight-bladed rotor outperformed the other two rotors, with an increase in efficiency of 40% and 79% compared to the Savonius and H-Darrieus geometry blades, respectively. The study highlights the importance of considering the rotor design in the optimization of the gravitational vortex turbine. The results provide valuable insights into the design parameters that can be used to enhance the turbine's performance. These findings can contribute to the development of more efficient and cost-effective gravitational vortex turbines for on-site power generation and consumption.

A Comprehensive Systematic Review of CO2 Reduction Technologies in China’s Iron and Steel Industry: Advancing Towards Carbon Neutrality

The iron and steel industry, a major energy consumer, faces significant pressure to reduce CO2 emissions. As the world’s largest steel producer, China must prioritize this sector to meet its carbon neutrality goals. This study provides a comprehensive review of various carbon reduction technologies to drive decarbonization in the steel industry. China’s iron and steel sector, which accounted for approximately 15% of the country’s total CO2 emissions in 2022, predominantly relies on coke and coal combustion. This study provides a comprehensive review of a variety of carbon reduction technologies to advance decarbonization in the iron and steel industry. This study categorizes carbon reduction technologies in the steel sector into low-carbon, zero-carbon, and negative-carbon technologies. Low-carbon technologies, which are the most widely implemented, are further divided into energy structure adjustment, material structure adjustment, energy efficiency improvement technologies, etc. This study specifically reviews dry quenching technology, high-scale pellet technology for blast furnace, and top pressure recovery turbine power generation technology. As a zero-carbon technology, hydrometallurgy is a central focus of this study and a key area of research within China’s iron and steel industry. While negative-carbon technologies are primarily centered around carbon capture, utilization technologies are still in early stages. By presenting the latest advancements, this study offers valuable insights and guidance to facilitate the iron and steel industry’s transition to a low-carbon future, crucial for mitigating global climate change.

A novel model-based diagnostics for identifying component degradations in gas turbines for power generation

Improving the accuracy of gas turbine performance diagnosis is important for reducing maintenance costs. Conventional model-based diagnostics use either compressor map adaptation based on correction curves or compressor map scaling based on an assumed ratio of fouling factors. However, they usually do not reflect the characteristics of the actual gas turbine. In this study, adaptation of both the compressor and turbine maps was carried out. The ratio of fouling factors was determined by quantifying the actual fouling factors so that the novel diagnostics could be applied to any gas turbine. The novelty of the proposed diagnostics is that it identifies component degradations individually, particularly distinguishing between compressor and turbine degradations using only measurement data. To demonstrate the capabilities of the proposed diagnostics, the method was applied to a 180-MW-class gas turbine operated over a long period with off-line washing. According to the results, the compressor air flow rate before off-line washing was reduced by 3.1 kg/s. Consequently, the power and efficiency of the gas turbine decreased by 3.5 MW and 0.43%p, respectively. The diagnosis results after off-line washing showed that the air flow rate and efficiency of the compressor were fully recovered, but the turbine efficiency was still degraded by 0.49%p. As a result, it was found that the gas turbine power and efficiency were not recovered by 1.2 MW and 0.33%p. The results showed that the component degradations could be identified individually. The novel diagnostics is expected to be used in a variety of strategies to reduce maintenance costs.

Effect of Electrolyte pH during Pretreatment of Carbon Electrodes on the Subsequent Kinetics of the VII/VIII and VIV/VV Reactions in Vanadium Flow Batteries

Growing environmental concerns and the depletion of fossil fuel reserves have prompted increased focus on renewable energy sources like wind and solar power.1-3 However, integrating these renewables into power grids is challenging due to their intermittent nature. Large-scale energy storage systems are seen as a solution to improve the reliability and efficiency of renewable energy. Vanadium flow batteries (VFBs) are gaining attention for their potential in large-scale energy storage due to the advantage of utilizing the same active element on both sides of the battery, which eliminates cross-contamination issues and extends the lifetime of the battery.4-6 A typical VFB consists of a cell stack and two external tanks containing electrolytes with redox active species, circulated through the cell stack via pumps. The negative half-cell contains V2+/V3+ (VII/VIII) species and the positive half-cell contains VO2+/VO2 + (VIV/VV) species, separated by an ion exchange membrane. Carbon or graphite felts are commonly used as electrodes in VFBs due to their high electrical conductivity, chemical stability, and availability.2,9 However, voltage inefficiencies arising from sluggish electrode kinetics can lead to increased overpotentials and reduced coulombic efficiency, impacting the overall energy efficiency of the battery.5,6 Therefore, it is important to investigate the electrode kinetics to better understand and improve the performance of VFBs.Various electrode treatments, including chemical, electrochemical, and thermal treatments, have been reported to have significant impacts on the carbon electrode kinetics.7-9 We have previously reported that cathodic treatment enhances the kinetics of the positive (VIV/VV) electrode but inhibits the kinetics of the negative (VII/VIII) electrode, while anodic treatment inhibits the kinetics of the positive electrode but enhances the kinetics of the negative electrode. 9-18 Other factors affecting the electrode activity include ageing of the electrode, the final treatment potential, the redox rest potential, and the treatment potential window.14,15 Recently we showed that the electrochemical activity of the VIV/VV and VII/VIII redox reactions in highly acidic vanadium electrolytes at electrochemically treated glassy carbon electrodes is also affected by the pH of the treatment electrolyte.19,20 The effect of pH of the treatment electrolyte was investigated for electrolytes from pH 0 to pH 5. The activities of carbon electrodes towards both the VIV/VV and VII/VIII redox reactions increase with increasing pH of the treatment electrolytes.In this presentation, we report detailed results on treating glassy carbon electrodes electrochemically at different pH and the subsequent effects on kinetics. The activity of variously pretreated electrodes towards both the VIV/VV and VII/VIII redox couples will be compared and contrasted, and the important differences discussed. Acknowledgements Varsha Sasikumar S P would like to thank the Irish Research Council (IRC) for a postgraduate scholarship to perform this research and acknowledges the facilitation of this research by the University of Limerick (UL) and the South East Technological University (SETU) in Ireland. References M. J. Leahy et al., Wind Power Generation and Wind Turbine Design, ed. W. Tong (WIT Press, Southampton) 661 (2010).C. Roth et al., (ed.), Flow Batteries: From Fundamentals to Applications (New York, Wiley) (2022).Z. Zhang et al., Renew. Sustain. Energy Rev., 148, 111263 (2021).M. Zarei-Jelyani et al., J. Appl. Electrochem., 54, 719 (2024).H. Agarwal et al., Adv. Sci., 11, 2307209 (2024).Z. Huang et al., ACS Sustainable Chem. Eng., 10, 7786 (2022).R. K. Sankaralingam et al., J. Energy Storage, 41, 102857 (2021).K. J. Kim et al., J. Mater. Chem. A, 3, 16913 (2015).M. A. Miller et al., J. Electrochem. Soc., 163, A2095 (2016).A. Bourke, et al., ECS Trans., 64, 1 (2014).A. Bourke et al., ECS Trans., 61, 15 (2014).A. Bourke et al., ECS Trans., 53, 59 (2013).A. Bourke et al., ECS Trans., 66, 181 (2015).M. Al-Hajji-Safi et al., ECS Trans., 109, 67 (2022).M. Al-Hajji-Safi et al., ECS Trans., 77, 117 (2017).A. Bourke et al., J. Electrochem. Soc., 163, A5097 (2016).A. Bourke et al., J. Electrochem. Soc., 162, A1547 (2015).A. Bourke et al., J. Electrochem. Soc., 170, 030504 (2023).V. Sasikumar et al., ECS Trans., 109, 107 (2022).V. Sasikumar et al., Electrochim. Acta., Under revision (2024).

Effect of Ceramic Matrix Composites on the Thermal Efficiency of a Power Generation Turbine

Abstract Ceramic matrix composites (CMCs) offer higher allowable temperatures and reduced weight, making them an attractive prospect for parts in the hot section of a gas turbine engine. As CMCs are increasingly adapted into aero and land-based engines, there is a need to quantify the performance increase based on the potential for reduced cooling and increased firing temperatures. In this work, two static hot section components—the first-stage turbine vane and the first-stage turbine tip shroud (outer casing above the blade)—of a mid-sized power generation engine were modeled. Informed approximations about part geometry and cooling architectures were made to determine the cooling requirements of each part. Thermal boundary conditions for the turbine tip shroud and turbine vane were generated as a function of coolant mass flowrate using data from literature and applied to a 2D finite element analysis of the parts to determine maximum temperatures for both metallic and ceramic materials. A gas turbine cycle model was developed to simulate the performance of a mid-sized power generation turbine and used to determine the increase in efficiency due to a reduction in the cooling requirement for the CMC part compared to a conventional metal superalloy-based part. The potential reduction in chargeable cooling seen for the tip shroud ring was between 0.09% and 0.4% of the compressor mass flowrate, which corresponds to an increase in thermal efficiency between 0.11% and 0.45%. A similar analysis of the turbine vane resulted in a cooling reduction of 10.71% at the maximum turbine entry temperature considered which corresponds to a 3.4% increase in thermal efficiency.

A novel proposal of using solar panels mounted on wind turbines for enhancement of power generation

To increase power generation, the next generation wind turbines are focusing more on hybrid systems. There is always a demanding need for more efficient wind power generation systems. In view of the improvements in the known types of turbines now available in the prior art, the present work proposes a novel hybrid wind and solar turbine construction wherein the same can be utilized for generating additional electrical power. A practical and feasible combination of wind turbine and solar panels has been designed. In this proposed novel arrangement, solar panels are secured to the surface of nacelle heli-hoist to supplement the power generation of a wind turbine.

Catch the wind: Optimizing wind turbine power generation by addressing wind veer effects.

Wind direction variability with height, known as "wind veer," results in power losses for wind turbines (WTs) that rely on single-point wind measurements at the turbine nacelles. To address this challenge, we introduce a yaw control strategy designed to optimize turbine alignment by adjusting the yaw angle based on specific wind veer conditions, thereby boosting power generation efficiency. This strategy integrates modest yaw offset angles into the existing turbine control systems via a yaw-bias-look-up table, which correlates the adjustments with wind speed, and wind veer data. We evaluated the effectiveness of this control strategy through extensive month-long field campaigns for an individual utility-scale WT and at a commercial wind farm. This included controlling one turbine using our strategy against nine others in the vicinity using standard controls with LiDAR-derived wind veer data and a separate 2.5 MW instrumented research turbine continuously managed using our method with wind profiles provided by meteorological towers. Results from these campaigns demonstrated notable energy gains, with potential net gains exceeding 10% during extreme veering conditions. Our economic analysis, factoring in various elements, suggests an annual net gain of up to approximately $700 K for a 100-MW wind farm, requiring minimal additional investment, with potential for even larger gains in offshore settings with the power of individual turbines exceeding 10 MW nowadays. Overall, our findings underscore the considerable opportunities to improve individual turbine performance under realistic atmospheric conditions through advanced, cost-effective control strategies.

Development of Detailed and Reduced Chemical Kinetic Models for Ammonia Gas Turbines

Abstract The power generation sector has been recently moving toward decarbonization, and there is an increased interest in replacing conventional fossil fuels with fuels that produce reduced/zero carbon emissions. One such fuel is ammonia (NH3). However, ammonia is hard to ignite, has a low flame speed, and produces a significantly large amount of nitrogen oxide (NOx) emissions. Hence, using 100% ammonia as fuel in gas turbines requires significant modifications and the development of novel combustors. Blending hydrogen with ammonia, however, helps in having better control over the combustion properties. For example, a 70%/30% mixture of NH3/H2 mixture has a flame speed comparable to natural gas. Before utilizing hydrogen-blended ammonia in an actual gas turbine combustor, thorough simulation studies are required to evaluate its performance, possible hazards, and emissions. The literature lacks well-validated chemical kinetic models for the combustion of hydrogen-blended ammonia for undiluted mixtures at gas turbine-relevant conditions (∼20 bar). Most models available in the literature have been developed for ammonia extremely diluted in diluents such as argon or nitrogen. Hence, in this work, we develop a detailed chemical kinetic model for hydrogen-blended ammonia combustion and validate it with a wide range of experimental data for both dilute and undiluted mixtures relevant to gas turbine operating conditions. We outline the strengths and weaknesses of the current mechanism to aid future users of our chemical kinetic mechanism. The detailed chemical kinetic mechanism was reduced to a smaller version (32 species mechanism) without significant loss in accuracy using the directed relation graph with error propagation (DRGEP) and full species sensitivity analysis. The resultant mechanism can predict a wide range of experimental results with the least cumulative error and will be a valuable tool in computational fluid dynamics (CFD) simulations that will enable the development of gas turbines for zero-carbon power generation.

A Novel Day-Ahead Optimization-Oriented Low-Carbon Economic Scheduling Scheme for Integrated Energy Systems

As the global energy structure undergoes transformation and the low-carbon development process continues to advance, integrated energy systems have progressively emerged as crucial technical support for achieving sustainable development. In this paper, a joint-day optimal scheduling model is put forward considering the existence of dispatchable resources in community integrated energy systems (CIES). The aim is to cut down the system operation cost and enhance energy utilization efficiency. This model is founded on the concept of energy hubs and combines the shiftable, transferable, and reducible characteristics of demand-side flexible loads. It includes gas turbine power generation systems, energy storage, as well as wind and solar renewable resources. System operation cost and carbon trading cost are comprehensively taken into account, and ultimately, the CIES low-carbon economic dispatch model with the lowest total cost as the optimization objective is established. The Yalmip toolbox and Cplex solver are employed to solve the model. The optimization results of flexible electric and thermal loads participating in dispatching under different scenarios are analyzed through simulation. The economic benefits of electric and thermal independent dispatching are compared and analyzed, and the economic benefits of electric and thermal coupled dispatching are verified. The study reveals that the rational scheduling of user-side flexible loads can notably reduce operating costs, lower the load peak-to-valley difference and carbon emissions, and boost the comprehensive economic and environmental benefits of the system.

Prediction of the Flame Characteristics of an Industrial Gas Turbine Operated With CO2-Diluted Air Through a High-Fidelity Numerical Analysis: A Comparison Between Flamelet Generated Manifolds and Artificially Thickened Flame

Abstract In light of the global commitment to decarbonize industrial processes, carbon capture and storage (CCS) plays a pivotal role in mitigating greenhouse gas emissions from gas turbine (GT) power generation processes. Achieving an efficient GT–CCS coupling requires the employment of high percentages of exhaust gas recirculation (EGR) to maximize the CO2 content at the CCS inlet. Nevertheless, such operating conditions pose critical challenges for conventional combustion systems due to reduced oxygen levels associated with higher EGR, limiting engine operability. To address this challenge, the development of innovative technical solutions is essential to extend the combustor operational capabilities at high EGR rates. For this goal, a significant number of computational fluid dynamics (CFD) simulations are required to identify the flame stability limits across various EGR levels and burner designs. It is imperative, in this context, to minimize computational costs while maintaining high accuracy. In this work, a comprehensive comparative study of an extended version of the flamelet generated manifolds (FGM) and the artificially thickened flame (ATF) model is performed through a large eddy simulation (LES)-based CFD analysis. The investigation is performed within the context of an industrial lean-premixed burner manufactured by Baker Hughes, operating with natural gas and CO2-diluted air at atmospheric pressure. While the extended-FGM has been previously presented by the authors in a study on the same test rig under standard air conditions, the current work aims to extend its application to critical oxygen-depleted conditions, where near-blowout phenomena such as flame liftoff and length elongation may become significantly pronounced. Numerical validation is carried out through a direct comparison of the computed averaged heat release, representing the flame topology, with detailed OH* chemiluminescence images from a test campaign conducted by the technology for high temperature (THT) Lab of the University of Florence. The experimental data will serve as the primary benchmark for assessing the models’ effectiveness in capturing the main dynamics of such critical operating conditions. Furthermore, potential disparities in both thermal and flow fields at the burner exit region between the two models will be discussed.

Numerical Investigation of Archimedes Screw Turbines under Low-Head Conditions

The development of screw turbines for micro-hydro power generation has garnered heightened interest lately, attributed to their capability to perform efficiently despite low head and low discharge. The present numerical work aims to evaluate the prospect of low-head water energy widely available in the Aceh region. In this region, the Archimedes Screw turbine is the most commonly used. In the present numerical study, the characteristics of the Archimedes screw turbine were studied under the constant of the head of 1 meter and the inclination angle of 30o, with the flow rate served as the varying parameter. In the simulation, a three-dimensional numerical investigation of pressure characteristics, flow velocity, and kinetic energy turbulence due to the change in the flow rates was carried out using the Navier-Stokes equations. Next, the turbulence model of K-Epsilon was also implemented. The comparisons between the experimental and the simulation results were carried out to ensure the accuracy of the simulation model, and the results indicated that the changes in flow rates have a marked influence on pressure distribution, the flow velocity field, and turbulent kinetic energy. It was found that the performance of the Archimedes double screw turbine was improved by increasing the flow rate due to the uniform distribution of pressure, flow velocity, and turbulent kinetic energy. Moreover, the optimum condition was achieved in a turbine with 8 screws. Therefore, maintaining the inflow rate is crucial as it significantly impacts the efficiency of the Archimedes Screw Turbine.

Measuring thermal diffusivity and gap conductance in uranium nitride and Zircaloy relevant for microreactor applications

Heat transfer across nuclear fuels and structural interfaces is an important factor for evaluating the performance of nuclear power systems. Specifically, heat generated as nuclear fuel fissions must be transported through the cladding material and through the reactor to reach the steam turbine for power generation. As new microreactor designs emerge, maximizing the efficiency of this heat transfer process becomes crucial to make them commercially viable. This article examines thermal diffusivity and gap conductance in uranium nitride (UN) fuel and Zircaloy-4 (Zry4) cladding using light flash analysis (LFA). Thermal diffusivity measurements were made on monolithic UN pellets and Zry4 exposed to carbon at peak operating temperatures of microreactors and show that carbon ingress has a minimal effect on thermal diffusivity when compared with identical materials not exposed to carbon. Evaluation of gap conductance at the UN-Zry4 interface was done using one-dimensional two-layer thermal transport models as a function of applied pressure. The results show that increasing pressure on the UN-Zry4 interface leads to gains in gap conductance per unit area in fuel-cladding assemblies at microreactor operating temperatures. While many other variables are expected to influence UN-Zry4 interfacial gap conductance (e.g. contact surface roughness, porosity, localized heating, environmental gas pressure), the work offers a demonstration of using a conventional LFA apparatus to determine this parameter at elevated temperatures.

Thermodynamic analysis and optimization of the semi-closed oxy-combustion supercritical CO2 power cycle with blending hydrogen into the natural gas/syngas

The semi-closed oxy-combustion supercritical CO2 (sCO2) cycle is regarded as a promising power cycle featuring the combined advantages of high efficiency and nearly 100 % CO2 capture. Blending hydrogen into fuels has attracted significant attention in the research of gas turbine and internal combustion engine power generation as it contributes to economy-wide decarbonization and bolsters the broader energy sources, especially green hydrogen. The present work carried out the thermodynamic analysis of a semi-closed sCO2 cycle to investigate how the hydrogen content in natural gas or syngas affects the operating parameters and performance. The results show that the energy efficiency decreases with increasing hydrogen content in natural gas whereas the maximum efficiency exists for the syngas with 60 % H2. The key factor is the increasing H2O content in the flue gas caused by adding hydrogen in fuels enhances both the heat-work conversion in the turbine and the heat transfer in the regenerator. The optimal turbine inlet temperature is around 1150 °C, which is the same as the basic cycle. The optimal turbine inlet pressure for natural gas and natural gas with 40 % H2 is both 28 MPa, while the optimal turbine inlet pressure decreases with hydrogen content in syngas. For all the fuels, the optimal turbine outlet pressure becomes lower for the higher hydrogen content. The maximum efficiencies obtained for natural gas, natural gas with 40 % H2, and syngas with 60 % H2 are 56.08 %, 55.52 % and 56.15 %. Finally, it is found that the recompression cycle and the multiple combustor arrangement (reheat cycle) cannot be the effective configuration for the semi-closed oxy-combustion sCO2 power cycle. The heat from the sCO2 recompression conflicts with the compression heat of the ASU, reducing the energy efficiency by 0.27 %, 0.34 %, and 1.23 % for the three fuels, respectively. The limitation of the regenerator allowable temperature requires the reheat cycle to either reduce the turbine inlet temperature or reduce the turbine outlet pressure, decreasing the energy efficiency for natural gas by 1.83 % and 6.38 % due to the reduced turbine output power or significantly increasing compression power.

Experimental Study of Natural Gas and Hydrogen Co-Firing Characteristics Using Different Types of Single Nozzles of F-Class Practical Gas Turbine Combustors

Abstract Recent research on co-firing natural gas and hydrogen, a carbon-free clean fuel, aims to reduce greenhouse gas emissions from aging gas turbine power generation, a key energy issue. This approach can enhance old gas turbines and increase the proportion of combined cycle power plant utilization as coal-fired power plants in Korea gradually shut down. This study seeks optimal operating conditions for mixed fuels without modifying the F-class gas turbine combustor. Experiments were conducted using four different types of fuel nozzles (F-Class DLN combustors) under varying loads and co-firing rates. The test used actual machine operating conditions from 30% to 100% thermal load, with hydrogen co-fired with natural gas up to 70% at each load. OH high-speed imaging and an OH-PLIF technique analyzed flame structure and characteristics. Dynamic pressure was measured to check combustion instability, and exhaust gas emissions were evaluated for combustion characteristics. Key findings include critical co-firing rates for each nozzle based on NOx emission levels and combustion dynamics. As the hydrogen co-firing rate increased, flame length decreased, and NOx levels rose rapidly beyond 30%vol. Dynamic pressure oscillations showed no significant variations compared to natural gas combustion. This study successfully derived a characteristic operation map for a single nozzle based on the hydrogen co-firing rate.

Global optimization of capacity ratios between electrolyser and renewable electricity source to minimize levelized cost of green hydrogen

This paper presents a novel and effective approach for calculating Levelized Cost of Hydrogen production across the globe, without requiring timely resolved modelling or data. We select characteristic production patterns of photovoltaic and wind turbine power generation based on location qualities indicated by full load hours. These representative patterns are applied worldwide on similar locations to evaluate the proportion of electricity that electrolyzers can use if they have a smaller capacity than the renewable electricity source. Hence, the ratio of capacities is optimized to minimize hydrogen cost. The findings from various worldwide locations reveal that decreasing electrolyzer capacity is economically beneficial across all locations for boosting full load hours and curbing investments, particularly in locations with lower electricity generation. Validation using precise electricity production timeseries in specific locations revealed minimal errors in the methodology, though the quality of the results is impacted by the seasonality index differences between representative and exact location.

Control of wind energy conversion systems with permanent magnet synchronous generator for isolated green hydrogen production

This paper addresses the design and analysis of the control system for a Wind Energy Conversion System (WECS) with a Permanent Magnet Synchronous Generator (PMSG) and its application for isolated green hydrogen production. The designed control maximizes the wind turbine (WT) power generation by regulating the electrolyzer current consumption, where the electrolyzer operates as a controlled load, ensuring power balance in the system and enabling the generation of maximum power from the WECS without the use of any energy storage system. The system involves directly integrating a WECS with an alkaline electrolyzer (AEL), and its configuration includes a WT with a PMSG, an AC/DC voltage source converter (VSC) acting as the generator side converter (GSC), and a DC/DC converter acting as the electrolyzer side converter (ESC) with Maximum Power Point Tracking (MPPT) control for the WT. The proposed control system has been fully modeled and tested through simulations in Matlab/Simulink, demonstrating its reliable performance under variable wind speeds. Simulation results illustrate how, over rated wind speeds, the pitch control limits the rotational speed and power to their maximum values, and at under rated wind speeds, the ESC control regulates the AEL current following the MPPT of the WT, while the GSC control maintains the DC bus voltage at its designated nominal value. Overall, the proposed control system shows robust and effective performance across the entire range of possible operational points, ensuring no wind generation power losses by following the maximum power point.

Multi-device wind turbine power generation forecasting based on hidden feature embedding

In recent years, the global installed capacity of wind power has grown rapidly. Wind power forecasting, as a key technology in wind turbine systems, has received widespread attention and extensive research. However, existing studies typically focus on the power prediction of individual devices. In the context of multi-turbine scenarios, employing individual models for each device may introduce challenges, encompassing data dilution and a substantial number of model parameters in power generation forecasting tasks. In this paper, a single-model method suitable for multi-device wind power forecasting is proposed. Firstly, this method allocates multi-dimensional random vectors to each device. Then, it utilizes space embedding techniques to iteratively evolve the random vectors into representative vectors corresponding to each device. Finally, the temporal features are concatenated with the corresponding representative vectors and inputted into the model, enabling the single model to accomplish multi-device wind power forecasting task based on device discrimination. Experimental results demonstrate that our method not only solves the data dilution issue and significantly reduces the number of model parameters but also maintains better predictive performance. Future research could focus on using more interpretable space embedding techniques to observe representation vectors of wind turbine equipment and further explore their semantic features.

Investigation and optimization into flow dynamics for an axial flow pump as turbine (PAT) with ultra-low water head

When the water downstream is abundant, axial flow pumps are often used as turbines (PAT) for reverse power generation to obtain additional benefits. However, due to the actual water level difference, PAT usually operates at off-design conditions. The CFD technology and entropy production theory were used to study the working performance, flow characteristics, and energy loss mechanism of the blade adjustable axial-flow PAT under a low water head. The results indicate that the strength of the tubular vortex at the pressure surface and the separation position of the tip-leakage-vortex at the suction surface depend on the inlet angle of the blade. The energy loss in the draft tube is influenced by the velocity circulation at the runner’s outlet, which depends on the blade’s outlet angle. Subsequently, the blade inlet and outlet angles in the runner were optimized. In turbine mode, the overall efficiency of the optimized runner increased by an average of 0.99 %. The blade pressure load distribution of the optimized runner has improved, and the pressure fluctuation in the draft tube is also under control. In pump mode, due to the increasing of the inlet angle within the same demand pump head range, the optimized runner’s pumping flow increases by an average of 2 m3/s.

An Approach to Improve Power System Resiliency in Grid-Connected Wind Turbine Generator Power System

An Approach to Improve Power System Resiliency in Grid-Connected Wind Turbine Generator Power System