Wind Model Research Articles

Optimization of the Offshore Wind Turbines Layout Using Cuckoo Search Algorithm

Wind turbines have gained popularity as one of the efficient micro grid energy generation sources over the years. However, wind energy yield has been greatly impacted by the wind farm wake effect, especially when the size of the wind farm becomes very large. One way to address this challenge is through wind turbine arrangements and their scalability. Developing effective means of optimizing wind farm configurations is a major concern for energy communities. This has continuously led to increased power generation and a corresponding cost reduction. As such, this research article developed an optimal large-scale offshore wind turbine placement based on wind farm layout design. The system developed focuses on wind turbine placement in wind farm layouts that have a negative influence on the capital investment due to the increasing wake effect thereby reducing energy production. A multi-objective function consisting of wake effect and component costs within the wind farm is formulated. After-which a cuckoo search algorithm technique is employed in the wind farm model to optimize the optimization problem (minimizing the wake effect while improving power output and cost). Four test case scenarios were considered when implementing the wind model. The results obtained from the developed scheme were compared with those obtained when other optimization techniques were used, using power output and cost as performance metrics. The obtained power output and cost for the test case scenario in the ideal wind turbine position on the wind farm are 18288.3KW, 19680.1KW, 18879.9KW, 21105.8KW and 26.9, 28.7, 26.9, and 29.8KW, respectively. This shows that the result obtained from the developed scheme outperformed that obtained from PSO and that of WOA.

Multi-actor approach to manage the water-energy-food nexus at territory scale

This study presents an innovative water-energy-food nexus (WEFN) generic multi-actor multi-level framework that simulates dynamic nexus systems and generates optimal resource management schemes and land-use allocation scenarios. The framework combines operational integrated multi-agent based simulations, dynamic agro-hydrological and renewable energy generation units (solar and wind) models and multi-criteria decision-making methods. It has been applied to a case study area of 800 km2 located downstream the Aveyron watershed, in Southwestern France. Local and regional strategic multi-criteria decision-making settings are compared. Under the local decision-making setting land-use allocation decisions are taken at agricultural parcel level whereas under the regional decision-making settings a single land allocation decision is taken for the whole territory. Possible land allocations are either crop rotations allocations, renewable energy generation units allocations or a mix of both. The framework is useful to generate scenarios of spatial allocations of renewable energy production units in an agricultural watershed facing water scarcity.

Operational characteristics of an integrated island energy system based on multi-energy complementarity

This study addresses the intermittent renewable energy supply and the large footprint of battery storage on an island reef in China by proposing an integrated energy system that incorporates hydrogen production, storage, and utilisation. Mathematical models for wind and photovoltaic power generation, energy storage, hydrogen production and utilisation, diesel generators, and energy management systems are established. Additionally, an integrated energy system is constructed using Simulink software to simulate and analyse its operational characteristics in various seasonal scenarios. The simulation results indicate that the surplus from wind power and photovoltaic systems, after supplying the load for over 70 % of the day, constitutes more than 40 % of the load demand. The energy storage system can maintain a maximum charging rate for more than 50 % of the day and a maximum discharge rate for less than 16.7 % of the day. The electrolysis tank produces hydrogen for more than 71 % of the day and simultaneously consumes up to 750 % of the load. The fuel cell consumes hydrogen for less than 12.5 % of the day and simultaneously provides up to 27 % of the load. Analysis revealed that the hydrogen system improves the energy utilisation, the control strategy realises stable supply and demand within the system.

Observational Constraints on Sunyaev–Zeldovich Effect Halos around High-z Quasars

We present continuum observations from the Atacama Large Millimeter/submillimeter Array of 10 high-redshift (2.2 ≤ z ≤ 2.7) ultraluminous quasars (QSOs) and constrain the presence of hot, ionized, circumgalactic gas in a stacking analysis. We measure a Compton-y parameter profile with a peak value of (1.7 ± 1.1) × 10−6 at a radius of ∼50 kpc. We compare our stacked observations to active galactic nucleus feedback wind models and generalized Navarro–Frenk–White pressure profile models to constrain the wind luminosity and halo mass of the stacked QSOs. Our observations constrain the observed average halo mass to M 500 < 1 × 1013 M ⊙ and the average feedback wind power <1 × 1012 L ⊙, which is <1% of the bolometric luminosity of the quasar.

A disc wind origin for the optical spectra of dwarf novae in outburst

ABSTRACT Many high-state cataclysmic variables (CVs) exhibit blue-shifted absorption features in their ultraviolet (UV) spectra – a smoking-gun signature of outflows. However, the impact of these outflows on optical spectra remains much more uncertain. During its recent outburst, the eclipsing dwarf nova V455 And displayed strong optical emission lines whose cores were narrower than expected from a Keplerian disc. Here, we explore whether disc + wind models developed for matching UV observations of CVs can also account for these optical spectra. Importantly, V455 And was extremely bright at outburst maximum: the accretion rate implied by fitting the optical continuum with a standard disc model is $\dot{M}_{\rm acc} \simeq 10^{-7}~{\rm M}_\odot ~{\rm yr^{-1}}$. Allowing for continuum reprocessing in the outflow helps to relax this constraint. A disc wind can also broadly reproduce the optical emission lines, but only if the wind is (i) highly mass-loaded, with a mass-loss rate reaching $\dot{M}_{\rm wind} \simeq 0.4 \dot{M}_{\rm acc}$, and/or (ii) clumpy, with a volume filling factor $f_V \simeq 0.1$. The same models can describe the spectral evolution across the outburst, simply by lowering $\dot{M}_{\rm acc}$ and $\dot{M}_{\rm wind}$. Extending these models to lower inclinations and into the UV produces spectra consistent with those observed in face-on high-state CVs. We also find, for the first time in simulations of this type, P-Cygni-like absorption features in the Balmer series, as have been observed in both CVs and X-ray binaries. Overall, dense disc winds provide a promising framework for explaining multiple observational signatures seen in high-state CVs, but theoretical challenges persist.

Impact of disc magnetisation on MHD disc wind signature

Context. Observations of blue-shifted X-ray absorption lines indicate the presence of wind from the accretion disc in X-ray binaries. Magnetohydrodynamic (MHD) driving is one possible wind-launching mechanism. Recent theoretical developments have made self-similar magnetic accretion-ejection solutions much more generalised, showing that wind can be launched at a much lower magnetisation than the equipartition value, which had previously been the only possibility. Aims. In this work, we model the transmitted spectra through MHD-driven photoionised wind models with different levels of magnetisation. We investigate the possibility of detecting absorption lines by upcoming instruments, such as XRISM and Athena. We investigate the robustness of the method of fitting asymmetric line profiles by multiple Gaussians. Methods. We used the photoionisation code XSTAR to simulate the transmitted model spectra. To cover the extensive range of velocity and density of the wind spanned over a large distance (∼105 gravitational radii), we divided the wind into slabs following a logarithmic radial grid. Fake observed spectra are finally produced by convolving model spectra with instrument responses. Since the line asymmetries are apparent in the convolved spectra as well, this can be used in future XRISM and Athena spectra as an observable diagnostic to fit for. We applied some amount of rigor in assessing the equivalent widths of the major absorption lines, including the Fe XXVI Lyα doublets, which will be clearly distinguishable thanks to the superior quality of future high-resolution spectra. Results. Disc magnetisation stands as another crucial MHD variable that can significantly alter the absorption line profiles. Pure MHD outflow models at low magnetisation are dense enough to be observed by the existing or upcoming instruments. Therefore, these models can serve as simpler alternatives to MHD-thermal models. Fitting with multiple Gaussians is a promising method for handling asymmetric line profiles, as well as the Fe XXVI Lyα doublets.

Renewable energy utilization and stability through dynamic grid connection strategy and AI-driven solution approach

The connection of renewable energy sources such as wind and solar power into the power grid can significantly reduce both costs and pollution emissions. However, the variability, volatility, and anti-peak regulation characteristics of renewable energy pose significant challenges for power system dispatch. This paper proposes a hybrid economic emission dispatch model (HDEED) for wind–solar–thermal-storage systems, with operational cost and pollution emission as objective functions. The study aims to develop optimal grid-connection strategies for clean energy by utilizing the energy-shifting capability of energy storage systems. This includes strategies based on optimal load fluctuation and optimal operation income for new energy stations. A generalized load fluctuation coefficient is proposed to assess load fluctuations after wind and solar energy integration, comparing and analyzing the performance of energy storage power stations with varying capacities. In terms of algorithm development, the paper proposes the Pelican optimization algorithm with a clustering strategy (POA-CS), specifically tailored to address the complexities of economic emission scheduling. The effectiveness of the proposed strategy and algorithm is validated using an enhanced IEEE-39 bus test system. Results indicate that the generalized load fluctuation coefficient under the optimal grid-connected strategy based on load fluctuation is 21% lower than that of direct grid connection of wind power and photovoltaic, leading to a significant reduction in net load fluctuation. Furthermore, under the optimal grid-connected strategy based on the operation income of new energy stations, the revenue of these plants increased by 22.40% compared to direct grid connections of wind power and photovoltaic systems. The POA-CS algorithm demonstrates superior performance, continuity, and smoothness in obtaining the Pareto optimal boundary under consistent testing conditions.

Runaway BN supergiant star HD 93840: Progenitor of an imminent core-collapse supernova above the Galactic plane

We present a quantitative spectral analysis of the extreme nitrogen-enhanced supergiant HD 93840 (BN1\,Ib) at an intermediate galactic latitude. Based on an optical high-resolution spectrum and complementary ultraviolet and infrared (spectro-)photometry, in addition to Gaia data, we carried out a full characterisation of the star's properties. We used both hydrostatic and unified (photosphere+wind) model atmospheres that account for deviations from local thermodynamic equilibrium. A highly unusual surface CNO-mixing signature and a marked stellar overluminosity compared to the mass imply a binary channel for the star's past evolution. The kinematics shows that it has reached its current position above the Galactic plane as a runaway star, likely ejected by the supernova explosion of its former companion star. Its current bulk composition, with a notably increased mean molecular weight due to core He- and progressed shell H-burning, suggests an advanced evolutionary stage. It is poised to yield a rare core-collapse supernova of a blue supergiant about ten OB star population scale heights above the Galactic disk relatively soon, contributing to the metal enrichment of the circumgalactic medium.

Retrieving Seismic Source Characteristics Using Seismic and Infrasound Data: The 2020 ML 4.1 Kiruna Minequake, Sweden

AbstractA minequake of magnitude ML 4.1 occurred on 18 May 2020 early in the morning at the LKAB underground iron ore mine in Kiruna, Sweden. This is the largest mining‐induced earthquake in Scandinavia. It generated acoustic signals observed at three infrasound arrays at 9.3 (KRIS, Sweden), 155 (IS37, Norway), and 286 km (ARCI, Norway) distance. We perform full‐waveform focal mechanism inversion based on regional seismic data and local infrasound data. These independently highlight that this event was dominated by a shallow‐depth collapse in agreement with in‐mine seismic station data. However, regional infrasound data cannot inform the inversion process without an accurate model of atmospheric winds and temperatures. Yet, our numerical simulations demonstrate a potential of using local and regional infrasound data to constrain an event's focal mechanism and depth.

Optimal planning and operation for a grid-connected solar–wind–hydro energy system in wastewater treatment plants

This study proposes a multi-objective optimization model for a grid-connected wind–solar–hydro system in wastewater treatment plants, addressing trade-offs among electricity utilization cost, self-sufficiency, complementary effect, and carbon emission. Two modes are explored: one allowing energy export and another leading to curtailment. A case study from a plant with design scale of 50,000 m3/day in China found that a higher complementary rate can slightly increase costs, lower self-sufficiency, and increase carbon emissions. Compared to the initial scheme without the solar–wind–hydro system, the design modes of export and curtail reduce electricity costs by 2.15 and 0.87 million CNY, carbon emissions by 2760 and 1439 tons annually, and increase self-sufficiency to 52% and 42%, respectively. The levelized cost of energy is 25% higher and total installed capacity decreases by 54% when surplus cannot be exported. A 6.7% curtailment minimizes the electricity utilization cost. Complementarity rates show seasonal fluctuations, peaking in August, with the highest yearly rate of 0.1528 at a solar-to-wind capacity ratio of 1.747. Output ratios remain stable across different treatment scales under curtailment mode: imports about 60%, wind and solar about 20% each, and hydropower 2%. Price changes and potential for zero-carbon operation are further discussed.

Multidimensional hybrid software-in-the-loop modeling approach for experimental analysis of a floating offshore wind turbine in wave tank experiments

A hybrid experimental modeling approach for floating offshore wind turbines (FOWTs) in a wave tank is presented. The method called real-time hybrid method (RTHM) or software-in-the-loop (SIL) includes physically reproduced hydrodynamic loads in the wave tank, with a Froude-scaled model while aerodynamic loads are reproduced on the model by an actuator. The force is applied on the tower top and calculated by a numerical simulation running in real-time as a function of the measured velocity and position of the physical model. Couplings between the platform motion, the aerodynamic loads and the wind turbine controller are hence accounted for. A new SIL actuator enabling the reproduction of a multi-component force at the tower top of an experimental scaled wind turbine model is developed, and the quantification of the accuracy of the replicated forces is studied. The test case includes a floating spar platform carrying a 10 MW horizontal axis wind turbine. The results show that this SIL actuator can accurately replicate the low and wave-frequency aerodynamic loads, which are essential for wave tank testing. Lastly, a case study of the wind turbine model in colinear and misaligned wind and wave conditions is presented, showing 3D forces and induced motions.

Wind energy relevant characteristics of turbulence over boreal forests

Turbulence statistics from three tall meteorological masts and LES in forested landscapes are compared to standard turbulence models used for wind turbine design. The comparison is split into different atmospheric conditions to highlight the impact of stratification on the character of turbulence. The aim of the work is to clarify to which extent standard turbulence models are accurate over forested regions. To this end, different spectral measures such as power spectra and coherence are examined as well as vertical profiles of turbulence characteristics relevant to the design and siting of wind turbines. The measurements are used to investigate vertically separated 2-point statistics and the LES to investigate laterally separated statistics. The results show that in neutral stratification and for smaller separation distances, in the order of half a radius, the standard turbulence models apply, but in non-neutral stratification, particularly in stable conditions and for larger separations the disparity between observations and standard turbulence grow. This effect is mainly attributed to the effect of stratification, while features in the turbulence statistics specifically related to the forest cover is absent at heights relevant to wind energy. The results of the study are expected to be of interest for turbine design purposes as well as wind resource estimation and wind modelling in forested areas.

A blind test on wind turbine wake modelling based on wind tunnel experiments: Phase I – The benchmark case

Wind turbine wake and modelling is crucial to optimizing future wind farm layouts and hence reducing the cost of energy. This paper presents the first phase of a blind test on modelling controlled and uncontrolled wind turbine wakes. The blind test is based on wind tunnel experiments of two model scale wind turbines (D = 1.1 m) one downstream of the other. The exercise is split into two phases and the first one is presented here, where participants are invited to simulate the baseline case, in which both turbines are aligned with the flow and there is no control on the either turbine. The objective of this phase is to ensure all participants can benchmark their numerical approach against a baseline open data set, where no wake control is applied. Experimental measurements include inflow velocity, turbine power and loads for a range of tip speed ratios. In the second phase, not presented here, the wake of the upstream turbine will be controlled and the performance of the downstream one will be recorded. This will be a blind test with the data not released prior to submissions. The present paper gives an overview of the initial, open benchmark case, including its objectives, methodology and experimental results.

Energy storage peak-shaving demand prediction based on an improved neural network with hidden layers

Abstract The result shows that the BP neural network has a very low convergent speed for load prediction, which leads to local optimization. This paper presents a modified GA for the optimization of the threshold value, the initial weight, and the addition of the smoothing coefficient. In addition, it improves the BP neural network’s adaptive learning speed and further improves the efficiency of the search. The proposed model is characterized by high convergent speed and global space retrieval capability. To validate the validity of the modified GA-BP model, the prediction of power load in some regions is made. Compared with the BP neural network forecast algorithm, this method has better performance in terms of prediction accuracy and takes less time in terms of prediction time than the BP neural network. In parallel, the realization of multiple sources of electricity from wind, solar, and heat storage is an important way to deal with large-scale new grid connections. Starting from an improvement in the efficiency of wind and PV generation, it is also possible to build a joint optimization scheduling model for wind, solar, and heat storage. The purpose of taking the minimum net load fluctuation is for optimization. Taking the typical output day of user scenarios as the optimization scenario, the scheduling strategies of wind power, PV, thermal units, and energy storage systems are introduced and simulated on the platform. It is proved that the proposed model can decrease the reduction ratio and the peak and valley load.

A wind farm planning method considering frequency security constraint based on wind farm participation in primary frequency regulation

Abstract Renewable energy sources such as wind power, connected to the grid on a large scale, reduce the rotational inertia and frequency regulation of the power system. Many studies have included frequency security constraints (FSC) in power system scheduling to ensure system frequency stability, but few studies have included FSC in grid planning. Therefore, this paper establishes a planning model for wind farms that considers the FSC based on the wind turbines’ participation in the primary frequency regulation (PFR) by obtaining the maximum deviation value constraint of the system frequency through the system frequency response (SFR) model. Tests were conducted on the IEE30-node system, and the results show that the proposed model enhances the system frequency response capability and ensures system security.

Bifurcation analysis and control of improved traffic flow model considering the effect of strong winds.

In recent years, the problem of traffic congestion has become increasingly serious, and research on traffic system control has become a new hotspot. Studying the bifurcation characteristics of traffic flow systems and designing control schemes for unstable support points can alleviate traffic congestion from a new perspective. This article improves the full speed differential model considering strong wind models from the perspective of bifurcation control to adjust traffic flow. This article theoretically proves the existence conditions of Hopf bifurcation and saddle node bifurcation in the model and finds the stability mutation point of the transportation system stability. A nonlinear system feedback controller was designed for unstable bifurcation points using Chebyshev polynomial approximation and random feedback control methods. Without changing the system equilibrium point, the advance, delay, and elimination of Hopf bifurcation were achieved, and the abrupt behavior of the transportation system was controlled, thereby alleviating traffic congestion. This article explains the changes in the stability of complex transportation systems from the perspective of bifurcation analysis, which can better capture the characteristics of traffic flow. By adjusting the control parameters in the feedback controller, the influence of boundary conditions on the stability of the transportation system is fully described, and the influence of unstable focal points and saddle points on the system is suppressed, thereby slowing down the traffic flow. In addition, unstable bifurcation points can be eliminated, and the Hopf bifurcation can be controlled to advance, delay, and disappear, thereby achieving control over the stable behavior of the transportation system. This helps alleviate traffic congestion and also helps describe actual traffic phenomena.

Deciphering Radio Emissions from Accretion Disk Winds in Radio-quiet Active Galactic Nuclei

Unraveling the origins of radio emissions from radio-quiet active galactic nuclei (RQ AGNs) remains a pivotal challenge in astrophysics. One potential source of this radiation is the shock interaction between AGN disk winds and the interstellar medium (ISM). To understand this phenomenon, we construct a spherical, one-zone, and self-similar expansion model of shock structure between ultrafast outflows (UFOs) and the ISM. We then calculate the energy density distribution of nonthermal electrons by solving the transport equation, considering diffusive shock acceleration as the acceleration mechanism and synchrotron and inverse Compton cooling as the cooling mechanisms. Based on the derived energy distribution of nonthermal electrons, we model the radio synchrotron spectrum of the shocked ISM. For the 15 nearby RQ AGNs hosting UFOs, we investigate the shocked ISM parameters required to model their observed radio spectra based on X-ray observations and measured UFO velocities. Radio spectra of 11 out of 15 nearby RQ AGNs would be explained by the AGN disk wind model. This is a compelling indication that shock interactions between AGN disk winds and the ISM could indeed be the source of their radio emissions. The typical predicted source size and magnetic field strength are several 100 pc and 0.1 mG, respectively. We also discuss whether our prediction can be tested by future radio observations.

Analytical Wake Modeling in Atmospheric Boundary Layers: Accounting for Wind Veer and Thermal Stratification

Reliable characterization of wind turbine wakes in the presence of Atmospheric Boundary Layer (ABL) flows is crucial to accurately predict wind farm performance. Wind veering in the ABL shears the wake in the lateral direction, and wind veer strength depends on the thermal stability of the ABL. Analytical wake modeling approaches must capture these ABL effects to ensure correct prediction of the wake structure under varied atmospheric conditions. To this end, a new physics-based analytical wake model is developed in this study that is capable of predicting the shape of wakes influenced by wind veer and thermal stratification effects. This model combines a novel ABL wind field model with the Gaussian wake model. The new ABL wind model is capable of predicting both the streamwise and spanwise velocity components in conventionally neutral (CNBL) and stable (SBL) ABL flows. The analytical expressions for both of these horizontal velocity components adhere to Monin-Obukhov Similarity Theory (MOST) in the surface layer, while capturing wind veering in the outer layer of the ABL. Incorporating this ABL model with the Gaussian wake model predicts laterally deflected wake shapes in a fully predictive and self-consistent fashion for a wide range of atmospheric conditions. The results also demonstrate that the enhanced wake model gives improved predictions relative to Large Eddy Simulations of power losses due to wake interactions under strongly stably stratified atmospheric conditions, where wind veer effects are dominant.

Dual Role of Accretion Disk Winds as X-Ray Obscurers and UV Line Absorbers in AGN

X-ray obscuration of active galactic nuclei (AGNs) is considered in the context of ionized winds of stratified structure launched from accretion disks. We argue that a Compton-thick layer of a large-scale disk wind can obscure continuum X-rays and also lead to broad UV absorption, such as in the blue wing of C iv; the former originates from the inner wind and the latter from the outer wind, as a dual role. Motivated by a number of lines of observational evidence showing strong AGN obscuration phenomena in Seyfert 1 AGNs such as NGC 5548, we demonstrate in this work, by utilizing a physically motivated wind model coupled to post-process radiative transfer calculations, that an extended disk wind under certain physical conditions (e.g., morphology and density) could naturally cause a sufficient obscuration qualitatively consistent with UV/X-ray observations. Predicted UV/X-ray correlation is also presented as a consequence of variable spatial size of the wind in this scenario.

Hot Gas Outflow Properties of the Starburst Galaxy NGC 4945

We analyze 330 ks of Chandra X-ray imaging and spectra of the nearby, edge-on starburst and Seyfert type 2 galaxy NGC 4945 to measure the hot gas properties along the galactic outflows. We extract and model spectra from 15 regions extending from −0.55 to +0.85 kpc above and below the galactic disk to determine the best-fit parameters and metal abundances. We find that the hot gas temperatures and number densities peak in the central regions and decrease along the outflows. These profiles are inconsistent with a spherical, adiabatically expanding wind model, suggesting the need to include mass loading and/or a nonspherical outflow geometry. We estimate the mass outflow rate of the hot wind to be 1.6 M ⊙ yr−1. Emission from charge exchange is detected in the northern outflow, and we estimate it contributes 12% to the emitted, broadband (0.5–7 keV) X-ray flux.