Medium Wind Turbines Research Articles

A Frequency Response Control Strategy for Medium Voltage Wind Turbines With Multiple Rotors

A Frequency Response Control Strategy for Medium Voltage Wind Turbines With Multiple Rotors

Ортогональные ветроэнергоустановки для нефтегазопромысловых объектов на суше и на море

Wind and solar power plants for autonomous power supply of small oil and gas facilities with a capacity of no more than 20 kW, wind power plants in their composition – 10 kW with a power factor (energy efficiency) of no more than 0.35–0.45 are considered. An improved design of an orbital wind power plant based on a combined H-Darye-Savonius rotor has been developed. Experiments on the laboratory installation showed that the maximum values of the power factor reached 0.60, which is much higher than that of the rotors of known types of wind turbines. The values of the CRDS power factor are calculated for various geometric dimensions of the N-Darye and Savonius rotors included in its composition. With an increase in wind speed to the nominal value of 9.0 m/s for small and medium power wind turbines and a rotor diameter of 15.0 m, the combined rotor power reaches almost 60 kW. The proposed orthogonal wind power plants with a nominal capacity of up to 60 kW will be able to be used together with other power plants for autonomous power supply at oil and gas field facilities on land and at sea, and in the future at intelligent fields.

Assessment of Correction Methods Applied to BEMT for Predicting Performance of Horizontal-Axis Wind Turbines

Blade Element Momentum Theory (BEMT) is the most used method to design horizontal-axis wind turbines worldwide. This is because BEMT has a low computational cost and easy numerical implementation. Additionally, it is demonstrated in the literature that the prediction of output power using BEMT agrees well with experimental data. Another important feature of the BEMT is its applicability to small, medium, and large-sized turbines. However, BEMT models are usually implemented and adjusted for a specific power range turbine, and they are not applied in a more general form. Thus, this article presents an analysis of additional correction methods for tip and root losses, high values of the axial induction factor, and high angle of attack to better represent horizontal-axis turbines in terms of numerical stability. The approach has the intention of combining several complementary correction methods strategically inserted in the BEMT in order to compile an algorithm that is more general, stable, and workable for any turbine size. The main contribution of this work is to propose a stable BEMT numerical algorithm through the assessment of the combination of the correction methods available in the literature, i.e., classical and modern ones. The algorithm ensures applicability for small, medium, and large-sized wind turbines, as well as being fast and easy to implement in any computer and extendable even to turbines with a diffuser. This approach is validated by comparing the results with experimental data from four turbines of different power ranges (1.9 kW to 7.3 MW). The results show the best approximations for performance power curves against the measured values of all turbines. Moreover, it is effective, less complex, and quick in analyzing the performance of those turbines. Furthermore, the need for high-performance computers to analyze the performance of horizontal-axis turbines is avoided.

A Study on the Improved Power Control Algorithm for a 100 kW Wind Turbine

In this study, a power compensation control algorithm was designed and validated for commercial 100 kW medium wind turbine models for power compensation due to additional generator loss. Generally, torque control considering generator efficiency is applied to a controller of a medium wind turbine; however, a control corresponding to a decrease in generator efficiency due to the surrounding environment is not possible. There is a possibility that an additional generator loss may occur due to the surrounding environment of the wind turbine already installed, and accordingly, a power compensation control algorithm is required because power is expected to decrease. The power compensation control algorithms may be divided into three methods according to a control strategy, and three power compensation control algorithms were explained and designed. The proposed power compensation control algorithms were validated using DNV’s Bladed program. The simulation conditions were selected at an average wind speed of about 18 m/s and normal turbulence model (NTM) Class A, and the additional generator loss was assumed to be 15%. The simulation comparison showed that the original power control algorithm had a deviation of 15.00% from the rated power due to a 15% generator loss, and the designed three power compensation control algorithms had a deviation of up to 0.05%.

Efficiency Optimization in Medium Power Wind Turbines: an Innovative Mechanical Pitch Control System

The paper illustrates the design of a new mechanical system for propeller blades pitch calibration in medium power wind turbines. The peculiarity of this system is its capacity of adjusting through a feedback control system, which allows the wind turbine to capture the maximum amount of energy from the wind. In this work an axial drive system was studied by means of racks capable of linearly adjusting the pitch of all wind turbine propeller blades in an intrinsically synchronous way, with an advantage over the traditional methods of propeller blades pitch calibration. For different wind speeds the system adjusts the blades angle of incidence in order to reduce the rotation speed and keep the system as close as possible to the pre-established design conditions generating maximum energy with a high efficiency. The manuscript examines the main analyses and simulations conducted during the design phase. These show that the proposed method allows to reach higher efficiencies with a greater intrinsic stability compared to the traditional pitch control mechanisms in medium power wind turbines. The experimental results on the first prototypes confirm the efficiency increase.

Orta ve Küçük Ölçekli Rüzgar Türbinlerinin Yaşam Döngüsü Boyutunda Sürdürülebilirliği: Literatür Taraması

With the growing interest in renewable energy systems, studies on the sustainability of small-scale wind turbines have been published in recent years. A literature review was conducted in this study to compile scientific studies conducted to evaluate the environmental effects of medium and small-sized wind energy systems using the life cycle assessment. Life cycle assessment is a method of evaluating the environmental sustainability of a product, process, or system that is becoming more important in the context of decisions and policies in the energy sector. The environmental effects of medium and small-sized wind turbines on the life cycle size have been investigated in this study, which looked at studies conducted since 2004. The vast majority of these studies conducted environmental sustainability assessments based solely on a few environmental impact indicators such as global warming potential. There are only a few studies that consider a wider range of environmental effects. The collection and analysis of studies examining the life cycle environmental sustainability of medium and small-scale wind turbines are important for determining the future vision of small-scale energy production systems.

PERFORMANCE EVALUATION OF SOME SELECTED WIND TURBINES IN HEIPANG WIND SPEED REGIME

Heipang in Plateau State is classified under moderate wind speed regime in Nigeria, thus, has high potential for wind electricity generation. Due to high cost, it is difficult to design a wind turbine for a particular site; therefore, the designer of the wind energy project has to choose from the available options in markets, which come in different sizes and speed characteristics. This paper is aimed at evaluating the performance of some selected wind turbines in Heipang wind speed regime. The method used is based on wind speed analysis and computation of the capacity factors of wind turbines expressed as a product of wind turbines’ power output models and probability distribution of wind speed regime of Heipang; and the total annual energy generation of the wind turbines using Wind Energy Resources Analysis (WERA) software. Results showed that Heipang has an annual mean wind speed of 6.3 m/s and its wind speed regime best fitted into Weibull probability distribution function with average Weibull shape and scale parameters of 3.05 and 7.03 m/s respectively at 10 m height. For small (<10kW), medium (10kW-250kW) and large (>250kW) wind turbines classifications; WT4, WT14 and WT25 have the highest capacity factors of 0.61, 0.7 and 0.53 respectively and WT2, WT22, WT27 have the highest total annual energy generation of 0.0054, 1.12 and 4.03 GWh/year respectively. In conclusion, Heipang has high wind speed potential for wind power technology and wind turbines with higher annual energy generation are better options for selections for wind power generation applications

Numerical Simulation and Wind Tunnel Investigation on Static Characteristics of VAWT Rotor Starter with Lift-Drag Combined Structure

In order to get rid of the impact of the global financial crisis and actively respond to global climate change, it has become a common choice for global economic development to develop clean energy such as wind energy, improve energy efficiency and reduce greenhouse gas emissions. With the advantages of simple structure, unnecessary facing the wind direction, and unique appearance, the vertical axis wind turbine (VAWT) attracts extensive attention in the field of small and medium wind turbines. The lift-type VAWT exhibits outstanding aerodynamic characteristics at a high tip speed ratio, while the starting characteristics are generally undesirable at a low wind speed; thus, how to improve the starting characteristics of the lift-type VAWT has always been an important issue. In this paper, a lift-drag combined starter (LDCS) suitable for lift-type VAWT was proposed to optimize the starting characteristics of lift-type VAWT. With semi-elliptical drag blades and lift blades equipped on the middle and rear part outside the starter, the structure is characterized by lift-drag combination, weakening the adverse effect of the starter with semi-elliptical drag blades alone on the output performance of the original lift-type VAWT and improving the characteristics of the lift-drag combined VAWT. The static characteristic is one of the important starting characteristics of the wind turbine. The rapid development of computational fluid dynamics has laid a solid material foundation for VAWT. Thus the static characteristics of the LDCS with different numbers of blades were investigated by conducting numerical simulation and wind tunnel tests. The results demonstrated that the static torque coefficient of LDCS increased significantly with the increased incoming wind speed. The average value of the static torque coefficient also increased significantly. This study can provide guidelines for the research of lift-drag combined wind turbines.

Measured wind and morphological characteristics of a peri-urban environment and their impact on the performance of an operational large-scale wind turbine

The market for single medium and large-scale wind turbines deployed at industrial consumer sites has future expansion potential, due to evolving electricity systems from centralised to distributed. Many industrial sites have low-rise buildings, typically found in peri-urban environments, such as at the edge of towns and cities. Unlike rural onshore wind farm sites, peri-urban wind environments can have more complex wind regimes with respect to turbulence, wind shear and gusts. The resulting wind conditions may influence a wind turbine’s energy performance and have turbulence characteristics that exceed current international turbine design standard specifications. These conditions can give rise to extra challenges in wind turbine micro-siting and reduce turbine operational lifetimes in peri-urban environments. This field study examines the impact of buildings on the wind characteristics and energy performance of an 850 ​kW wind turbine in a peri-urban environment. A 16 sector directional analysis of long-term SCADA data, onsite LiDAR measurements and measurements from a local rural met mast, combined with a morphological analysis of local buildings show that buildings higher than 20% of hub-height with sector wise plan area fractions greater than 20% are significant. New peri-urban micro-siting recommendations and revisions to IEC standard normal wind turbulence models are suggested.

도서지역 적용을 위한 230 kW급 저풍속 중형 풍력발전기의 전자장해석

Recently, a project to build a carbon zero island with no carbon emissions has been carried out by replacing diesel generators with renewable energy sources in island areas where diesel generators supplied local loads as independent systems. To minimize damage to the lives of islanders, low noise wind generators should be installed by adjusting the rated speed. In islands with low loads, wind turbines that are more efficient than medium-sized wind turbines should be installed. In this study, the generator field analysis and characteristics were analyzed to develop 230 kW-class low wind medium-wind turbine technology. The electromagnetic field analysis program used Maxwell. As a result, the cogging torque was reduced, and the initial maneuver wind speed and loss value were lowered. Hence, the output amount was increased with high efficiency.

Integrated Design of Aerodynamic Performance and Structural Characteristics for Medium Thickness Wind Turbine Airfoil

The currently geometric and aerodynamic characteristics for wind turbine airfoils with the medium thickness are studied to pursue maximum aerodynamic performance, while the interaction between blade stiffness and aerodynamic performance is neglected. Combining the airfoil functional integration theory and the mathematical model of the blade cross-section stiffness matrix, an integrated design method of aerodynamic performance and structural stiffness characteristics for the medium thickness airfoils is presented. The aerodynamic and structural comparison of the optimized WQ-A300 airfoil, WQ-B300 airfoil, and the classic DU97-W-300 airfoil were analyzed. The results show that the aerodynamic performance of the WQ-A300 and WQ-B300 airfoils are better than that of the DU97-W-300 airfoil. Though the aerodynamic performance of the WQ-B300 airfoil is slightly reduced compared to the WQ-A300 airfoil, its blade cross-sectional stiffness properties are improved as the flapwise and edgewise stiffness are increased by 6.2% and 8.4%, respectively. This study verifies the feasibility for the novel design method. Moreover, it also provides a good design idea for the wind turbine airfoils and blade structural properties with medium or large thickness.

Design and Simulation of an LQR-PI Control Algorithm for Medium Wind Turbine

In this paper, a new linear quadratic regulator (LQR) and proportional integral (PI) hybrid control algorithm for a permanent-magnet synchronous-generator (PMSG) horizontal-axis wind turbine was developed and simulated. The new algorithm incorporates LQR control into existing PI control structures as a feed-forward term to improve the performance of a conventional PI control. A numerical model based on MATLAB/Simulink and a commercial aero-elastic code were constructed for the target wind turbine, and the new control technique was applied to the numerical model to verify the effect through simulation. For the simulation, the performance data were compared after applying the PI, LQR, and LQR-PI control algorithms to the same wind speed conditions with and without noise in the generator speed. Also, the simulations were performed in both the transition region and the rated power region. The LQR-PI algorithm was found to reduce the standard deviation of the generator speed by more than 20% in all cases regardless of the noise compared with the PI algorithm. As a result, the proposed LQR-PI control increased the stability of the wind turbine in comparison with the conventional PI control.

Harvesting wind gust energy with small and medium wind turbines using a bidirectional control strategy

Wind energy is an important renewable source with a stochastic nature. To capture this energy, variable speed generators are installed in wind towers and different maximum power point (MPP) tracking (MPPT) strategies have been developed in literature to maximise the output power. However, in gusty weather, wind turbines fail to track the optimum operating point due to their relatively high inertia. This paper proposes an innovative MPPT strategy to capture the energy of wind gusts. The developed controller consists of a conventional TSR control together with a bidirectional controller, which takes over the control of the rectifier under varying wind condition. The simulation results show an overall efficiency improvement and more stability for the proposed strategy.

Analysis of wind energy potential and wind energy development to evaluate performance of wind turbine installation in Bali, Indonesia

In recent years, Wind power generation in Indonesia is no longer a new issue. Indonesia has average velocity from 2 m/s to 7 m/s. With the characteristic it, Indonesia is suitable for small (10 kW) and medium wind turbine installation (10-100 kW. Based on the monitoring data from meteorological, climatological, and geophysical agency (BMKG), the average wind velocity in Bali is 2 m/s – 5m/s, hence Bali has potential to development and utilization the source for wind turbine installation, There are four stations of BMKG in Bali, which each station is supervise the region. Weibull distribution has been represented on this research to calculate and determine the probability of the each of region to know the availibility of the source. Literally, Jembrana station has the lowest availability of power available from the district and cities in Bali, with 0-0.2 W/m2, compared with some districts and cities in Bali, with wind density power between 0-2.88 W/m2 and also the KHK station has the highest probabiity of wind velocity than the other regions. Reconstruction design had been done, with basic data from probability in Bali. The result shows that the redesign of wind turbine give an effective power to extract the wind source.

Desing of wind propellers for horizontal axis

The GEOM research seedbed of the Universidad Distrital Francisco José de Caldas is developing low and medium power wind turbines, and here we present an advance. Wind energy is a very important source of renewable energy and an excellent alternative for the transition to sustainable energy that the world needs. It is known that horizontal axis wind turbines are more efficient energetically, and that the propeller is determinant for this efficiency; therefore, the correct geometric design of the propeller is essential for an optimum wind turbine. This article analyzes the most relevant aspects in the design of a wind propeller, using MATLAB® software to illustrate its behavior, and suggests an ideal airfoil for wind applications.

A boundary layer scaling technique for estimating near-surface wind energy using numerical weather prediction and wind map data

A boundary layer scaling (BLS) method for predicting long-term average near-surface wind speeds and power densities was developed in this work. The method was based on the scaling of reference climatological data either from long-term average wind maps or from hourly wind speeds obtained from high-resolution Numerical Weather Prediction (NWP) models, with case study applications from Great Britain. It incorporated a more detailed parameterisation of surface aerodynamics than previous studies and the predicted wind speeds and power densities were validated against observational wind speeds from 124 sites across Great Britain. The BLS model could offer long-term average wind speed predictions using wind map data derived from long-term observational data, with a mean percentage error of 1.5% which provided an improvement on the commonly used NOABL (Numerical Objective Analysis of Boundary Layer) wind map. The boundary layer scaling of NWP data was not, however, able to improve upon the use of raw NWP data for near surface wind speed predictions. However, the use of NWP data scaled by the BLS model could offer improved power density predictions compared to the use of the reference data sets. Using a vertical scaling of the shape factor of a Weibull distribution fitted to the BLS NWP data, power density predictions with a 1% mean percentage error were achieved. This provided a significant improvement on the use of a fixed shape factor which must be utilised when only long-term average wind speeds are available from reference wind maps. The work therefore highlights the advantages that use of a BLS model for wind speed and NWP data for power density predictions can offer for small to medium scale wind energy resource assessments, potentially facilitating more robust annual energy production and financial assessments of prospective small and medium scale wind turbine installations.

Design of a novel open space test rig for small scale wind turbine

In the present paper, an innovative and cost-effective open test rig for small and medium wind turbines is proposed. The main aim is to develop a valid alternative to wind tunnels, which present unresolved problems such as the unmatched Reynolds numbers for downscaled wind turbine tests. The proposed test bench concept is an open field, subsonic facility for horizontal and vertical axis wind turbines. The core of the test bench is a cluster of axial fans, positioned at a given height from the ground, which generate an air flow suitable for testing a wind turbine placed in front of the fans. The present work aims at investigating the feasibility of this novel concept of test rig for small wind turbines having a rotor diameter smaller than 5 m. A thorough CFD analysis is performed in this paper in order to assess the characteristics of the wind generated by the fans in terms of uniformity and intensity, even in case of atmospheric disturbances. The developed CFD modelling is also instrumental in both determining the maximum rotor diameter that can be tested and selecting the correct position for a wind turbine in the proposed open test rig.

Electricity-Generating Wind Turbine from Electric Bicycle Motor

Wind energy is one type of renewable energy which does not cause pollution. Presently, there is a technological development to apply wind energy for the electricity generation. Wind energy is used to replace fossil energy, such as oil and coal, causing environmental pollution. In Thailand, the studies of wind energy application to generate electricity have been promoted. Nowadays, there is number of small and medium wind turbines used for electricity generation in buildings, houses and small communities. This project took a 48 volts, 1,000 watt electric bicycle motor to apply in order to make a saline county wind turbine to generate electricity. The turbine consisted of 6 rotor blades. Each blade was 1.5 meters long, and was made from 150 x 130 centimeter synthetic fabrics. A rotor of the turbine was connected with a rotor of the electric bicycle motor through a 1:7.5 gearbox to increase the rotational speed of the electric bicycle motor. From the experiment, it was found that the invented saline county wind turbine started rotating at the wind speed of 1.5 m/s and generated 3 phases of AC voltage. Average voltage in each phase was 6 volts at the rotational speed of 60-80 rpm. As seen from the test, at the maximum wind speed of 4.7 m/s, 11-12 volts of AC voltage in a single phase was produced with the approximate 130-140 rpm rotational speed of the motor. When connecting the generated AC voltage to rectifier and filter circuits to convert it into DC voltage for battery charging purpose, the maximum wind speed at 4.7 m/s generated approximately 15-16 volts of DC voltage. This capacity was sufficient for 12-volt battery charging in a real use.

Wind Resource Mapping Using Landscape Roughness and Spatial Interpolation Methods

Energy saving, reduction of greenhouse gasses and increased use of renewables are key policies to achieve the European 2020 targets. In particular, distributed renewable energy sources, integrated with spatial planning, require novel methods to optimise supply and demand. In contrast with large scale wind turbines, small and medium wind turbines (SMWTs) have a less extensive impact on the use of space and the power system, nevertheless, a significant spatial footprint is still present and the need for good spatial planning is a necessity. To optimise the location of SMWTs, detailed knowledge of the spatial distribution of the average wind speed is essential, hence, in this article, wind measurements and roughness maps were used to create a reliable annual mean wind speed map of Flanders at 10 m above the Earth’s surface. Via roughness transformation, the surface wind speed measurements were converted into meso- and macroscale wind data. The data were further processed by using seven different spatial interpolation methods in order to develop regional wind resource maps. Based on statistical analysis, it was found that the transformation into mesoscale wind, in combination with Simple Kriging, was the most adequate method to create reliable maps for decision-making on optimal production sites for SMWTs in Flanders (Belgium).

The Application of Roof Ventilator for Electricity Generation

Wind energy is one types of renewable energy and it does not cause pollution. Therefore, presently, there is the technological development of applying wind energy for the electricity generation. Wind energy is used to replace fossil energy such as oil and coal, causing environmental pollution. Moreover, Thailand has promoted the studies of wind energy application to generate electricity. Nowadays, there is number of small and medium wind turbines used for electricity generation for buildings, houses and small communities. Since Thailand is located in the tropical climate, the buildings, houses and industrial facilities prefer installing roof ventilators to vent hot air out of the roof. Therefore, the author proposed the roof ventilator system equipped with a small direct current electric generator. A 18-watt DC generator was installed in 24-inch roof ventilator and carry around rotation of the generator by gear to the rotation axis of roof ventilator. The results of the study were found that roof ventilator would begin to generate a voltage of 0.2 - 0.3 volt at wind speed of 0.5 meters per second. When the wind speed is higher than 2 meters per second, it would produce about 3.5 volts. However, when connecting the voltage produced by the generator to the DC Step-Up Converter, it was found the wind speed of 5 meters per second. DC generators can produce a voltage of 3 volts. With the DC Step-Up Converter, the voltage would increase to approximately 12 volts and can the current to 220mA, which is sufficient level to work with light-emitting diode lamp. In sum, the system of roof ventilator with a small DC generator could be applied to generate electricity for various households.