Variable Wind Speed Conditions Research Articles

The Windcatcher: A Renewable-Energy-Powered Device for Natural Ventilation—The Impact of Upper Wing Walls

In recent years, there has been increased interest in natural ventilation solutions as a means to achieve sustainable and energy-efficient building design. Windcatchers, ancient Middle Eastern architectural elements, have surfaced as viable passive cooling devices in modern architecture, thereby enhancing interior air quality and reducing the reliance on mechanical ventilation systems. Integrating upper wing walls (UWWs) is hypothesized to augment a windcatcher’s effectiveness by optimizing wind capture, air circulation, and thermal regulation. Therefore, this study aimed to explore the influence of incorporating a two-sided windcatcher with UWWs, with a particular emphasis on the effect of the UWW angle on ventilation performance within building spaces. To achieve this aim, a series of numerical simulations were conducted to assess the synergy between the windcatcher and the wing wall configuration with varying UWW angles and under varying wind speed conditions. As the first step of the research methodology, the CFD model was validated through a comparison between the numerical results and the experimental data. The findings showed good agreement between these methods. In the next phase, windcatchers with different UWW angles spanning the range of 0° to 90° were subjected to rigorous evaluation. The results revealed that the configuration with a 30° angle exhibited the optimal performance concerning critical ventilation parameters encompassing the airflow rate, air change rate, and mean age of air. Finally, the selected configuration underwent an evaluation under diverse wind speed conditions, which affirmed that even under low-wind-speed conditions, the windcatcher provides ventilation levels that align with the standard requirements.

Maximum Power Point Tracking Based on Wind Speed Prediction

A control method for MPPT (maximum power point tracking) based on wind speed prediction is proposed to address the issue of slow attainment of optimal speed values by wind turbines in variable wind speed conditions in the wind power system. Initially, the wind speed variation value is accurately estimated using the SSA-BP neural network based on historical wind speed data. Subsequently, the MPP (maximum power point) is calculated considering the optimal blade-tip speed ratio, thereby enhancing the tracking speed of the system. Simulation results demonstrate that this method enables real-time estimation of wind speed variation, improves wind energy utilization rate, and maximizes the utilization of wind energy.

Smoothing Intermittent Output Power in Grid-Connected Doubly Fed Induction Generator Wind Turbines with Li-Ion Batteries

Wind energy is an increasingly important renewable resource in today’s global energy landscape. However, it faces challenges due to the unpredictable nature of wind speeds, resulting in intermittent power generation. This intermittency can disrupt power grid stability when integrating doubly fed induction generators (DFIGs). To address this challenge, we propose integrating a Li-ion battery energy storage system (BESS) with the direct current (DC) link of grid-connected DFIGs to mitigate power fluctuations caused by variable wind speed conditions. Our approach entails meticulous battery modeling, sizing, and control methods, all tailored to match the required output power of DFIG wind turbines. To demonstrate how well our Li-ion battery solution works, we have developed a MATLAB/Simulink R2022a version model. This model enables us to compare situations with and without the Li-ion battery in various operating conditions, including steady-state and dynamic transient scenarios. We also designed a buck–boost bidirectional DC-DC converter controlled by a proportional integral controller for battery charging and discharging. The battery actively monitors the DC-link voltage of the DFIG wind turbine and dynamically adjusts its stored energy in response to the voltage level. Thus, DFIG wind turbines consistently generate 1.5 MW of active power, operating with a highly efficient power factor of 1.0, indicating there is no reactive power produced. Our simulation results confirm that Li-ion batteries effectively mitigate power fluctuations in grid-connected DFIG wind turbines. As a result, Li-ion batteries enhance grid power stability and quality by absorbing or releasing power to compensate for variations in wind energy production.

Sequential frequency regulation strategy for DFIG and battery energy storage system considering artificial deadbands

To address the issues of the mechanical stress of doubly-fed induction generator (DFIG) and the service life of energy storage systems (ESSs) resulting from excessively and frequently participate in grid frequency regulation (GFR), this paper suggests a sequential GFR of the DFIG and ESS considering the artificial dead-bands. Firstly, the system frequency deviation expression is derived considering the dead-band to analyze the influences of the dead-bands on the grid frequency dynamics. Secondly, based on the artificial dead-bands, the GFR process is divided into three zones: the GFR zone of DFIG, the transaction zone of DFIG and ESS, and the GFR zone of ESS. To avoid the large mechanical stress of the wind turbines and shallow charging and discharging phenomenon of the ESS, the DFIG provides GFR function to mitigate the system frequency fluctuations, while ESS provides frequency regulation function to arrest the grid frequency variation taking into account the condition of state-of-charge constraints for severe frequency disturbances. Finally, simulations are conducted to verify the effectiveness of the proposed strategy under varying wind speed conditions combined with large disturbance. The results show that the proposed sequential GFR can maintain the frequency support while reducing the negative effects of mechanical fatigue of the DFIG and service life of ESS.

Design and Optimisation of Horizontal Axis Wind Turbine Blades Using Biomimicry of Whale Tubercles

Wind speed is the major factor in generating power in a wind turbine. However, due to the non-optimum and redundant design of wind turbine blades, not nearly enough wind is captured for utilization. In the present study, modifications were done on the leading edge of the HAWT blade using tubercles showing their effects on aerodynamic performances. From this research, the following results found concerning the performances of HAWT with leading-edge tubercles were that; blades with tubercles on the leading edge will have superior performance in the post-stall regime by 27%, tubercles with a smaller amplitude and lower wavelength will produce higher lift and lower drag in the low wind speed condition, and tubercle blade will have a stable and smooth performance in varying wind speed conditions, producing higher torque and power at low wind speed. Using a small wind turbine model, SolidWorks Motion Analysis Simulation was used for dynamic modeling to evaluate and determine the force and torque of the mechanical structure. These results were compared and examined using standard wind turbine blades which showed an improvement of 30% in efficiency.

A semicircular wall for harvesting wind energy from vortex-induced vibration and galloping

Harvesting energy from ambient air is crucial for sustaining the operation of low-power electronic devices under autonomous conditions. In this study, a specially designed semicircular wall with a thin splitter plate was proposed, behind which the wake exhibited evolution from vortex-induced vibration (VIV) to galloping. Benefiting from this peculiar flow pattern, a piezoelectric energy harvester placed in the cylinder wake can perform well under variable wind speed conditions. The effects of aspect ratio (α) and nondimensional afterbody length (l*) of the semicircular wall on the energy harvester's performance were experimentally examined. The results showed that the aspect ratio was highly correlated with the modes of flow-induced vibrations. When 2/3 ≤ α ≤ 4/3 and l* = 1/2, the harvester experienced VIV, transition from VIV to galloping, and galloping with a continuously increasing wind speed. Frequency analysis further revealed that the resonance force and lift instability caused by vortex shedding of the semicircular wall might arise almost simultaneously, with the latter serving as the driving factor in the evolution from VIV to galloping. It is also found that the harvester operated efficiently at wind speeds of 1.0–12.0 m/s, and an appropriate nondimensional afterbody length was required to achieve high-level power outputs. These findings provide beneficial suggestions for developing the coupled VIV-galloping energy harvesters.

Active power control strategy of DFIGs in flexible interconnected distribution network

In the development of new-type power system, the flexible interconnected distribution network becomes a better inclination. With the continuous increase of wind power generation in the flexible interconnected distribution network, the frequency stability issue caused by the high randomness of wind power generation has become increasingly prominent. This paper suggests an advanced active power strategy of double-fed induction generators (DFIGs) based on modifying power tracking curves in the interconnected distribution network for smoothing out the fluctuations of the system frequency. To this end, the various power tracking operation is used to participate in power smoothing instead of maximum power tracking operation so as to fully utilize the large rotor inertia of the double-fed induction generators for smoothing out the fluctuations of the power output of double-fed induction generators and system frequency. The control gain for the various power tracking operation is determined by the instantaneous system frequency deviation and rotor speed of the DFIG. Based on the modified IEEE 14 power system, simulation results successfully proved that the suggested advanced active power strategy is benefit for reducing the fluctuations of the output power of the DFIG and suppressing the maximum system frequency deviations with the scenario of continuously varying wind speed conditions.

Maximum Power Control and Optimization of Switched Reluctance Generators for Wind Turbines

In this paper, a maximum power control and optimization of a 4-phase 8/6-pole Switched Reluctance Generator (SRG) are realized for a wind energy conversion system by using MATLAB/Simulink. Unlike conventional generators, using of the SRGs has increased in variable speed wind turbines due to important advantages such as lower copper losses, simple structure, flexible control, and a good performance in a wide speed range. However, since SRGs work with switching logic, their torque production is fluctuating and optimum turn-on/turn-off angles of the phases must be determined to work as a generator. Therefore, in this study, these angles are optimized based on the speed of the SRG and Maximum Power Point Tracking (MPPT) is realized. Besides, a voltage control is provided by keeping the DC bus voltage at the output of the system constant at the desired value with the help of a chopper controlled unloader. The results obtained from the optimized model for variable wind speed conditions are compared with that of the unoptimized model. It is observed that the SRGs can work more stable with a proper optimization method and the power obtained from the system follows the maximum output power.

COMPARATIVE PERFORMANCE ANALYSIS ON ARTIFICIAL NEURAL NETWORK BASED MPPT CONTROLLER WITH CONVENTIONAL CONTROLLER FOR GRID CONNECTED WIND ENERGY CONVERSION SYSTEM

This paper focuses on the development of ANN based MPPT interfaced Permanent magnet synchronous generator (PMSG) for wind energy conversion system (WECS). It focuses on design and modeling aspects of the completely different elements of the WECS like the fundamental model of ANN based MPPT controller, MLI, wind turbine, optimum maximum power point tracking system utilizing MATLAB/Simulink. Major object is to extract the maximum energy from the wind which confirms a highest efficiency of developed system. The thesis shows the model of wind turbine together with the model of PMSG. The ANN based mostly MPPT approach used right here is predicated on Perturbation and observation (P&O). To complete the process of modeling and simulation the platform of MATLAB/Simulink is utilized. Developed ANN are most efficient technique compared to conventional methods. It achieves maximum power with more stability, precision and better performance with good dynamic response under variable wind speed conditions. It exhibits the enhancements for the developed system and control action for balance/unbalanced steady state in addition to transient, dynamic response circumstances.

Dynamic response of hybrid energy storage based virtual inertial support in wind application

The replacement of conventional synchronous generator (SG) with wind energy conversion system (WECS) greatly reduces the available inertial support in the electrical network. In order to avoid mechanical stress on wind turbine (WT) which is caused by kinetic energy (KE) extraction in providing the virtual inertial support (VIS), this paper proposed an improved technique in converting a hybrid energy storage (HES) into VIS during disturbances for wind turbine systems. The complementary behaviour of supercapacitor (SC) and battery energy storage (BES) offers a great deal of faster and limitless VIS. The trade-off between SC and BES has been achieved through a modified formulation of total available inertial time constant for HES-based VIS. To realize this, the new SC's voltage and BES's voltage are kept updated before being used to form the SC's and BES's reference current in the proposed model. Alongside in operating the HES-based VIS, this paper also introduced a modified energy management system (EMS) by fully utilizing the advantages of the high-power density of SC and the high-energy density of BES in handling disturbances. This modified control technique greatly provides faster and continuous VIS throughout the disturbances compared to the sole energy storage of SC and BES. In addition, based on the tested system of fixed wind speed and variable loads, the proposed HES-based VIS significantly improved the frequency nadir and peak frequency by 3.5 % and 2.7 % respectively. Additionally, the proposed HES-based VIS shows a significant improvement during variable wind speed and load conditions.

Robust H2-Optimal TS Fuzzy Controller Design for a Wind Energy Conversion System

In this paper, robust optimal control of an uncertain wind energy conversion system (WECS), described by a Takagi–Sugeno fuzzy model, is proposed to guarantee the maximum power trajectory tracking (MPTT). The design of the fuzzy optimal control is based on a quadratic criterion related to the maximum power tracking error. The proposed fuzzy controller allows to regulate the rectified direct current (DC) voltage of the variable-speed wind turbine by adjusting the duty cycle of a boost converter. Linear matrix inequality (LMI) conditions, ensuring the optimal H2 tracking error, are proposed for the controller gain design. Simulation as well as experimental tests are performed for efficiency evaluation of the established MPPT fuzzy control scheme under variable wind speed conditions.

A new optimal model predictive control scheme for a wind energy conversion system

AbstractThe correct management of power exchange between the doubly‐Fed induction generator (DFIG) and the grid depends on the effective optimal operation of the DFIG based wind energy conversion system (WECS). A modified optimal model predictive controller (MPC) architecture for WECS is proposed in this paper. The proposed scheme is carried out in two stages, as follows: (a) Using the MPC model and the tracking factor, an optimal control law is created, and (b) the aforementioned optimized issue is addressed using the linear matrix inequality (LMI) approach. Some improvements were made to the conventional LMI‐based MPC technique to lower the high computational complexity. To perform active and reactive power control in DFIG, the proposed approach is applied on the rotor‐side converter (RSC) control. The control law is divided into two sections. The first section deals with rotor current, while the second section deals with the RSC switching states. The LMI is used in the second portion of the control law to find the best switching state solution. The proposed method was created using the MATLAB/SIMULINK environment and tested in a 1hP DFIG‐WECS setup. By comparing the obtained results to conventional LMI‐PI, MPC‐based WECS, the effectiveness of the obtained results is verified. Variable wind speed conditions are used to vary all the results. Integral absolute error, integral time absolute error, and Integral square error measurements are used to compare the tracking performance index of all methods.

Performance Evaluation of Grid-Connected Wind Turbine Generators

The risk of oscillation of grid-connected wind turbine generators (WTGs) is well known, making it all the more important to understand the characteristics of different WTGs and analyze their performance so that the problems’ causes are identified and resolved. While many studies have evaluated the performance of grid-connected WTGs, most lack clarity and precision in the modeling and simulation techniques used. Moreover, most of the literature focuses on a single mode of operation of WTGs to analyze their performances. Therefore, this paper updates the literature by considering the different operating conditions for WTGs. Using MATLAB/SIMULINK it expands the evaluation to the full range of vulnerabilities of WTGs: from the wind turbine to grid connection. A network representing grid-connected squirrel-cage induction generator (SCIG) and doubly-fed induction generator (DFIG) wind turbines are selected for simulation. The performances of SCIG and DFIG wind turbines are evaluated in terms of their energy generation capacity during constant rated wind speed, variable wind speed, and ability of fault-ride through during dynamic system transient operating conditions. The simulation results show the performance of DFIG is better than SCIG in terms of its energy generation capacity during variable wind speed conditions and active and reactive power control capability during steady-state and transient operating conditions. As a result, DFIG wind turbine is more suitable for large-scale wind power plants connected to weak utility grid applications than SCIG.

Advanced Direct Vector Control Method for Optimizing the Operation of a Double-Powered Induction Generator-Based Dual-Rotor Wind Turbine System

The main goal of this paper is to increase the active/reactive power extracted from variable-speed dual-rotor wind power (DRWP) based on doubly-fed induction generators (DFIG) by optimizing its operation using advanced direct vector control. First, the dynamic modeling of different parts of the system is introduced. The DFIG is modeled in the Park reference system. After that, the control techniques are introduced in detail. Direct vector command (DVC) with four-level fuzzy pulse width modulation (FPWM) is used to control the rotor current, thereby controlling the reactive power and active power of the generator. Then, use the neural network design to replace the traditional proportional-integral (PI) controller. Finally, the Matlab/Simulink software is used for simulation to prove the effectiveness of the command strategy using 1.5 MW DRWP. The results show good performance in terms of response time, stability, and precision in following the reference under variable wind speed conditions. In addition, the total harmonic distortion (THD) value of stator current is about 0.13%, being a bit less than other THD values reported in the literature.

An adaptive droop control strategy with smooth rotor speed recovery capability for type III wind turbine generators

This paper presents an adaptive droop control scheme with smooth rotor speed recovery capability for doubly-fed induction generators (DFIGs, type III wind turbine generators) to improve the frequency nadir, minimize the second drop in the frequency, and regulate the time to meet the MPPT curve. To this end, an adaptive droop gain that decays with time is proposed, the initial value of which determined according to the wind speed. The effectiveness of the proposed adaptive droop control scheme is verified using a modified IEEE 14-bus system under various wind speeds, wind power penetration levels, and variable wind speed conditions. Simulation results in EMTP-RV indicate that the proposed adaptive droop control scheme is beneficial to improving the frequency nadir, preventing DFIGs from stalling, and minimizing the second drop in the frequency under various conditions.

Analysis on the influence of sinusoidal wind on the structure of pumping unit based on dynamics of solid-fluid interaction

China National Petroleum Corporation Dingbian oilfield is located in the wind field area of the beam pumping unit affected by the wind load, occurred several pumping unit bracket bending, beam fracturing, horsehead off and horsehead drop and other serious accidents, endanger the equipment and personnel safety. However, there is little research on the influence of beam pumping unit under wind load. Based on the dynamics of solid-fluid interaction theory and the standard k- turbulence model, this paper calculated the polished rod load range of the pumping unit according to the actual working condition of Dingbian oilfield, and established the CYJ10-4.2-53 numerical model of wind field. Under the sinusoidal variable wind speed conditions, the stress and deformation of the beam loader with different sizes of wind load on the beam loader were compared to those of the different sorts. The stress and deformation of the two different types of pumping unit were compared under the wind load. The results show that under the influence of wind load, the rig of the pumping unit bracket has a serious bending deformation, and the safety risk of the front end of the horsehead along the wind load is deformed. When the wind speed reaches 24.48m/s, the horsehead and barcket’s offset is the largest to the top dead point by the wind load, The minimum impact is affected by the wind load at the bottom dead center, The maximum offset of the horsehead and the bracket reached 8.5 mm and 2.16 mm. The research work of this paper provides a scientific basis for the improvement of safety structure for pumping unit in the wind field area.

Fuzzy Logic Control Based Maximum Power Point Tracking for Wind Energy Conversion System

Variable speed operation and direct drive wind turbines are the modern developments in the technology of Wind energy conversion system (WECS). WECS comprises a Permanent Magnet Synchronous Generator (PMSG) driven by a wind turbine, a generator side AC/DC rectifier, boost converter and a grid-side DC/AC converter and grid. The wind turbine converts part of the kinetic energy of the wind into mechanical energy which intern is converted into electrical energy via the generator. Since the generator output frequency is variable depends on the wind conditions, the FLC based MPPT is used to extract the maximum possible output power by controlling the generator speed. In this, the grid connected wind energy conversion system is considered. Wind turbine, PMSG model and FLC algorithm were simulated in Matlab/Simulink and the mechanical and electrical characteristics such as rotor speed, torque, induced voltage and current have been observed for various wind speeds. Also the DC link voltage has been measured with IGBT based controlled rectifier mode to stabilize the output frequency. From the simulation results, FLC based MPPT method has proven that it can extracted the maximum output power for the varying wind speed conditions.

Fractional Order Controller based Maximum Power Point Tracking Controller for Wind Turbine System

The wound rotor type Doubly Fed Induction Generator (DFIG) based adjustable velocity wind generator system is the most promising wind turbine system in the wind industry. A fractional-order proportional-integral-derivative (FOPID) based modified Incremental Conductance (INC) maximum power point tracking (MPPT) controller is proposed for DFIG based wind turbine (WT) system. The simulation of the proposed MPPT controller for DFIG based wind turbine system has been carried out in MATLABTM/SIMULINK with buck converter and resistive load for varying wind speed conditions. The FOMCON toolbox with the Nedler-Mead optimization algorithm is used to design an optimized Fractional order controller. Simulation results of the suggested controller are compared with conventional Perturb and Observe (P&O), INC, INC with integral action (INC-Integral) MPPT methods. The simulation results show that the proposed INC-FOPID MPP tracking controller is more efficient and produces more output power as compared to other MPPT techniques.

Implementation of Equilibrium Optimizer Algorithm for MPPT in a wind turbine with PMSG

This paper proposes a new equilibrium optimizer algorithm to extracting the maximum power point tracking which is proposed in permanent magnet synchronous generator under randomly different varying wind speed conditions. It was inspired by controlled volume mass balance modes for estimating dynamic and equilibrium states. The equilibrium optimizer algorithm can mutate the random solving a problem via exploration and exploitation. A particle with its concentration updates its concentration with particular terms. It defined as best-so-far solution, called the equilibrium candidate and the other is equilibrium state, which encourages a particle to global search the domain. The tracking performances of equilibrium optimizer algorithm based trackers firstly are evaluated based on MATLAB software. Results of equilibrium optimizer are compared to two categories of existing optimization methods, including the most well-known genetic algorithm, particle swarm optimization. The performance of the equilibrium optimizer algorithm is analyzed, evaluated and compared based on some key parameters, which are the active power, and turbine power factor under randomly different varying wind speed conditions. Additionally, the obtained results show that the equilibrium optimizer tracker has superiority compared with in all the studied cases

Energy efficiency of wind power plants in various wind condition

The present paper determines the optimum energy operation area of an electric wind power system, under time varying wind speed conditions. The determinations of the optimal area, from the energy point of view, is done based on experimental values from the Romanian black sea cost, Dobrogea area. The optimum operation area is defined by the optimal mechanical velocity, ωOPTIM. For this, the dependence between the wind speed, v, and ωOPTIM are computed based on the current wind speed and the current mechanical velocity ω. Due to the high inertia of the wind turbine (WT), the generators speed is not able to follow the changes of the wind speed. Knowing the optimum value ωOPTIM, the solution is to determine the load at the permanent magnet synchronous generator (PMSG) in order that the mechanical speed should timely reach his optimum.