Wind Turbine Power Generation Research Articles

A New Synchronization Method of Double Fed Induction Generator Wind Turbines to the Grid

Meeting grid code requirement creates an obligation to smart WTs disconnection following some electrical or mechanical events. Increasing the penetration level of wind turbines (WTs) in different voltage levels of the network have a major effect on this condition. In this regard, soft and rapid synchronization control of doubly fed induction generator (DFIG) to reduce the dynamic and transient effects of DFIG on a smart grid is very important. This paper gives a review on WTs power generation and a basic requirement to operate in a stable manner in connection to the network at first. After that, different startup and synchronization methods will be described. Then, a new synchronization method for grid connection of DFIG driven by WT is proposed. In this method, the rotor side converter is synchronized with the induced voltage at the rotor winding of DFIG while the stator windings have been connected to the grid and the rotor accelerates normally with the wind torque. This startup process is soft and the synchronization is carried out between two low voltages with very low frequency and may overcome some difficulties and limitations of previous methods since it uses the rotor side converter as power electronics switches instead of the mechanical circuit breaker at stator side and causes the synchronization to be more accurate and controllable. The proposed method is evaluated with EMTDC/PSCAD simulation to show the performance of soft starting synchronization with lower electrical transients in comparison with traditional methods.

Frequency stabilization of isolated and grid connected hybrid power system models

Abstract This paper investigates the load frequency control (LFC) of two different configurations of power system model. The first one is worked as an isolated hybrid power system (HPS) (IHPS) while the second one is a grid tied HPS (GHPS). In IHPS, the power generating units are diesel engine generator (DEG), wind turbine generator (WTG) and solar thermal power generation (STPG). It is considered in such a way that the generation persists throughout the day with uninterrupted power supply. The energy storage device used in this work is superconducting magnetic energy storage (SMES). The three scenarios considered in isolated mode are (a) HPS with one DEG, one WTG and one STPG, (b) HPS with one DEG and one STPG and (c) HPS with one DEG and one WTG. As concerned to GHPS, a combination of WTG and steam thermal power plant is considered. A conventional proportional-integral-derivative (PID) controller has been used as supplementary control mechanism. The PID controller gains and the tunable parameters of the SMES are tuned by the use of quasi-oppositional harmony search (QOHS) algorithm. Initially, integral of time absolute error based objective function is minimized and, subsequently, three performance indices such as integral of absolute error, integral of square error and integral of time square error are calculated to test the designed efficiency of the proposed QOHS based PID controller. The transient responses of systems pertaining to step and random changes in the load demand are analyzed. The simulated results obtained by the QOHS algorithm reveals that it may be imposed to boost LFC performance of the power system.

The effects of installation configuration and solidity on the power generation of a linear cascade wind turbine

PowerWindow is a Linear Cascade Wind Turbine (LCWT) capable of generating electricity in very low blade speed ratios, which makes it a safe power generator in built environments. The power generation mechanism and aerodynamic performance of PowerWindow were investigated using experimental prototyping and computational fluid dynamic simulations in a previous study. Due to the limited suitable locations for installing the device in grounded configuration, this study investigates elevated and ducted installation configurations. In the elevated configuration PowerWindow is installed on a tower or in between two tall buildings. In ducted configuration it is installed inside a ducted area such as a through-building opening. Aerodynamic performances of the elevated and ducted PowerWindow are investigated and compared, using computational fluid dynamic simulations. It is shown that the coefficient of performance of the ducted PowerWindow with 12% is about 50% higher than the elevated one with 8%. The effect of solidity is also investigated on the flow mechanism and power generation. The results show that increasing solidity results in greater increase in power generation of the ducted configuration compared to the elevated one. This study also investigates effect of increasing solidity on the required pressure gradient and recommends an efficient solidity for each configuration based on the installation circumstances.

Probabilistic Placement of Wind Turbines in Distribution Networks

DOI: 10.26650/electrica.2018.001 This study presents an efficient approach for determining the optimal locations of wind turbines (WTs) in distribution systems, which considers the existing uncertainties in the power generation of WTs and the load demand of consumers. The daily load profiles of the seasonal and geographical-dependent behaviors of WTs are also considered. The proposed probabilistic approach is based on scenario tree modeling, and each scenario is assessed in regard to power loss minimization. Then, the TOPSIS (technique for order preference by similarity to an ideal solution) method is adopted to regulate the optimal placement of WTs considering the average value and the standard deviation of active power losses as possible attributes. This approach enables a multi-attribute analysis of the search space to yield a more efficient solution. Detailed simulation studies, conducted on IEEE 33-bus test system, are utilized to examine the effectiveness of the proposed method. The results of this study are discussed in depth.

Model Predictive Control of PMSG-Based Wind Turbines for Frequency Regulation in an Isolated Grid

This paper proposes a frequency regulation strategy applied to wind turbine generators (WTGs) in an isolated grid. In order to complement active power shortage caused by load or wind speed change, an improved deloading method is proposed to improve the regulation capabilities in different speed sections and to provide WTG power reserves. Considering torque compensation may cause power fluctuation, speed reference of a conventional pitch control system should be reset. Moreover, to suppress disturbances caused by load and wind speed, as well as overcome the dependence on system parameters, a model predictive control (MPC) method is presented to generate torque compensation for each deloaded WTG, which allows each WTG to react to the disturbance differently, depending on its generator speed and the frequency deviation. Hardware-in-the-loop simulation and experimental results show that the proposed strategy can enhance the frequency response ability during load changes, and smooth power fluctuations resulting from wind speed variations.

Aerodynamic analysis of a linear cascade wind turbine

AbstractThis paper develops an analytical model to investigate the aerodynamic of the power generation of a linear cascade wind turbine, referred to as PowerWindow. Based on blade element momentum theory, this analytical model elucidates some flow characteristics of PowerWindow such as axial induction factor and local instantaneous angle of attack along the blades. The model also provides an understanding of the effects of blade pitch angle, blade speed ratio, and solidity on the angle of attack, axial induction factor, and power generation of PowerWindow when operating in “elevated” position. In elevated position, PowerWindow is installed on a tower as opposed to directly mounted on a roof. The validity and accuracy of the analytical model are verified with computational fluid dynamic simulations. The results indicate that by doubling the solidity or increasing the blade pitch angle by 8°, the coefficient of performance of PowerWindow increases from 8% to 12% and 16%, respectively. The analytical model can serve as the tool to find the design parameters of PowerWindow and their influence on power generation for given life wind condition.

Investigation of wake characteristic of a 30 kW rated power Horizontal Axis Wind Turbine with wake model and field measurement

A field measurement and wake model based on experimental data were introduced to investigate the wake characteristics of a HAWT (Horizontal Axis Wind Turbine) in a wind farm. In the present study, a HAWT generator of capacity 30 kW with the rotor diameter of 10.0 m was used. Firstly, the reference wind was measured with inflow measurement mast. And then, the wake flow was examined in the different tip speed ratios and pitch angles at the wind turbine wake position of x/D = 2.0 by ultrasonic anemometers, three-cup type anemometers and wind vane. Finally, the wake velocity distribution was predicted by the wake model with Gaussian function. As a result, the non-dimensional wind velocity ratio UNR reached the minimum value around y/R = 0.50 and increased as it went laterally away from y/R = 0.50. Furthermore, the non-dimensional wind velocity ratio UNR decreased with the increase of the pitch angle. When the pitch angles were 0°, 2° and 4°, the minimum UNR were about 0.77, 0.78 and 0.84 at the horizontal position of y/R = 0.5. Meanwhile, the full wake widths at half maximum of 1.04, 0.98 and 1.09 were obtained at the pitch angle of 0°. This study provided rich information for the prediction of annual power generation of the downstream wind turbine in wind farm.

Comparative analysis of maximum power point tracking controller for wind energy system

ABSTRACTThis paper proposes an adaptive maximum power point tracking (MPPT) control method to achieve the maximum power from the wind turbine (WT) power generation system. The MPPT control method has a vital role to find the maximum power point, and also compute the simulation results in both analysis such as offline using MATLAB/SIMULINK™ and online using OPAL-RT simulator. The proposed adaptive perturb and observe (P&O) algorithm provides better results using the OPAL-RT simulator compared to the P&O method using MATLAB/SIMULINK™. The power generation through doubly fed induction generator (DFIG) WT system is becoming important day by day throughout the world. The simulation result by OPAL-RT simulator showed that the efficiency of WT-DFIG has been enhanced.

Evaluation of the Effect of Spar Cap Fiber Angle of Bending–Torsion Coupled Blades on the Aero-Structural Performance of Wind Turbines

This paper presents a comprehensive study of the evaluation of the effect of spar cap fiber orientation angle of composite blades with induced bending–torsion coupling (IBTC) on the aero-structural performance wind turbines. Aero-structural performance of wind turbines with IBTC blades is evaluated with the fatigue load mitigation in the whole wind turbine system, tower clearances, peak stresses in the blades, and power generation of wind turbines. For this purpose, a full E-glass/epoxy reference blade has been designed, following the inverse design methodology for a 5-MW wind turbine. An E-glass/epoxy blade with IBTC and novel, hybrid E-glass/carbon/epoxy blades with IBTC have been designed and aeroelastic time-marching multibody simulations of the 5-MW turbine systems, with the reference blade and the blades with IBTC, have been carried out using six different randomly generated turbulent wind profiles. Fatigue-equivalent loads (FELs) in the wind turbine have been determined as an average of the results obtained from the time response of six different simulations. The results reveal that certain hybrid blade designs with IBTC are more effective in fatigue load mitigation than the E-glass–epoxy blade with IBTC, and besides the fiber orientation angle, sectional properties of hybrid blades must be adjusted accordingly using proper number of carbon/epoxy layers in the sections of the blade with IBTC, in order to simultaneously reduce generator power losses and the FEL.

Hybrid Genetic Algorithm Fuzzy-Based Control Schemes for Small Power System with High-Penetration Wind Farms

Wind is a clean, abundant, and inexhaustible source of energy. However, wind power is not constant, as windmill output is proportional to the cube of wind speed. As a result, the generated power of wind turbine generators (WTGs) fluctuates significantly. Power fluctuation leads to frequency deviation and voltage flicker inside the system. This paper presents a new methodology for controlling system frequency and power. Two decentralized fuzzy logic-based control schemes with a high-penetration non-storage wind–diesel system are studied. First, one is implemented in the governor of conventional generators to damp frequency oscillation, while the other is applied to control the pitch angle system of wind turbines to smooth wind output power fluctuations and enhance the power system performance. A genetic algorithm (GA) is employed to tune and optimize the membership function parameters of the fuzzy logic controllers to obtain optimal performance. The effectiveness of the suggested controllers is validated by time domain simulation for the standard IEEE nine-bus three-generator test system, including three wind farms. The robustness of the power system is checked under normal and faulty operating conditions.

Evaluation of wind energy potential in the south-south geopolitical zone of Nigeria

This study examined wind energy potential of six selected locations the South-South geopolitical zone of Nigeria using 10 year wind data obtained at a height of 10m as a possible location for energy generation from wind. The obtained data showed that the annual mean wind speed for Asaba, Benin, Calabar, Port Harcourt, Uyo, and Warri were 3.3m/s, 3.3m/s, 4.4m/s, 3.4m/s, 3.5m/s and 3.7m/s respectively, with corresponding mean power density of 21.8W/m 2 , 21.4W/m 2 , 35.8W/m 2 , 23W/m 2 , 25.2W/m 2 , and 30.8W/m 2 .. The mean energy output of 183.4KWh/m 2 , 205.4KWh/m 2 , 311.7KWh/m 2 , 200.9KWh/m 2 , 220.9KWh/m2, and 274.3KWh/m2 were found for the respective locations. The corresponding annual mean wind speed with maximum energy ranged from 4.1m/s to 4.4m/s with Calabar station found to be the most suitable site for the installation of wind turbine for power generation. The overall mean wind power densities and the annual mean power densities were under class 1 of wind classification scheme indicating that, the mean wind speed fell short of required standard of 6m/s for large-scale installation of wind energy generation. Nevertheless, the power generated could be improved using suitable wind turbines at reasonable heights. Keywords: Mean wind speed, Wind power density, Wind energy, Renewable energy

Power generation of small wind turbine: Under high-speed operation

Mechanical energy is produced through the rotation of wind turbine blades by air that converts mechanical energy into electrical energy. Wind turbines are usually designed for particular applications, and design characteristics may vary depending on the area of use. The variety of applications is reflected on the size of turbines and their infrastructures. Wind turbine performance may be enhanced by analyzing the small horizontal axis wind turbine (SHAWT) under high-wind-speed operation. This work analyzes the implementation of the SHAWT and investigates its performance in simulation and real life. The power performance of the SHAWT, which largely depends on the real structure of the rotor geometry and aerodynamic test, was simulated using ANSYS Fluent software at different wind speeds of up to 33.33 m/s (120 km/h) to numerically investigate actual turbine operation. Dynamic mesh and user-defined function (UDF) were used to revolve the rotor turbine via wind. Simulation results were further validated by experimental data, and good matching was achieved. A car alternator was formed and used as a small horizontal wind turbine to reduce energy production cost. Consequently, the alternator-based turbine system was found to be a low-cost solution for the exploitation of wind energy.

A Study on Capacity Credit and ESS Evaluation for WTG and Multi-ESS in Power System

This paper proposes a new method for evaluating Effective Load Carrying Capability (ELCC) and Capacity Credit (CC) of a power system including Wind Turbine Generator (WTG) combined with Multi Energy Storage System (ESS). The WTG can only generate electrical power when the wind is available. Because of the fluctuation of wind speed, WTG generates intermittent power. In the reliability viewpoint of power system, the intermittent power of WTG is similar to the probabilistic characteristics based on the on-off power due to the mechanical availability of conventional generators. Therefore, high penetration of WTG will cause difficulties in power system operation. The high penetration of numerous and large capacity WTG can risk the power system adequacy, quality, and stability. This study develops a new method to assess how much the penetration of WTG can be extended when WTG is combined with ESS. This paper demonstrates various case studies of ELCC and CC of a power system containing WTG combined with Multi ESSs using a model system similar to Jeju island power system in Korea.

Spline model for wake effect analysis: Characteristics of a single wake and its impacts on wind turbine power generation

ABSTRACTUnderstanding and quantifying the wake effect plays an important role in improving wind turbine designs and operations, as well as wind farm layout planning. The majority of the current wake effect models are physics based, but these models have a number of shortcomings. Sophisticated models based on computational fluid dynamics suffer from computational limitations and are impractical for modeling commercial-sized wind farms, whereas simplified physics-based models are generally inaccurate for wake effect quantification. Nowadays, data-driven wake effect models are gaining popularity as the data from commercially operating wind turbines become available, but this development is still in its early stages. This study contributes to the general category of data-driven wake effect modeling that makes use of actual wind turbine operational data. We propose a wake effect model based on splines with physical constraints incorporated, which sets out to estimate wake effect characteristics such as wake width and wake depth under single-wake situations. Our model is one of the first data-driven models that provides a detailed account of the wake effect. Prediction accuracy of the proposed spline model, when compared with other alternatives, also confirms the benefit of incorporating the physical constraints in the statistical estimation.

A comparative design study and analysis of inner and outer rotor permanent magnet synchronous machine for power generation in vertical axis wind turbine using GSA and GSA-PSO

In wind energy conversion system, an electric generator is coupled with a wind turbine. The wind turbine is either vertical axis or horizontal axis wind turbine. To increase the efficiency the gear driven generator has been replaced by directly driven generator. This paper recounts the design optimization of inner and outer rotor permanent magnet synchronous machine of rating 500KVA, 3.3kV, 3-phase, and 600rpm. The weight of the generator has been taken as an objective function. The gravitational search algorithm and its hybridization with particle swarm optimization have been used as tools for optimization. The temperature rise, efficiency, regulation and maximum flux density in stator teeth are taken as constraints for design problem. The results of both types of generator configurations are obtained and compared. It is found that the efficiency of outer rotor permanent magnet synchronous generator is improved by 2.19% and regulation by 2.83% as compared to inner rotor permanent magnet synchronous generator. Lower temperature rise as 22.61°C is observed for outer rotor permanent magnet synchronous generator whereas it is 31.18°C in case of outer rotor permanent magnet synchronous machine. Further, the sensitivity analysis has been performed over design parameters using local sensitivity method for both generators.

Optimal allocation of wind turbine generator in active distribution network

Nowadays, more and more wind turbine generators (WTGs) are being integrated into power systems. In this paper, an optimal WTG allocation model with the objective of minimizing the annual cost is proposed. The model can take into account the time‐sequential correlation between the wind speed and load demand, as well as four kinds of active management measures, i.e. regulating the on‐load tap changer of the transformer, curtailing the output power of WTG, regulating the power factor of WTG, and managing the demand side. The time‐sequential correlation is handled by the joint probability distribution method. A hybrid solving strategy combining the fuzzy adaptive particle swarm optimization algorithm and primal‐dual interior point method is developed to get the optimal solutions. Case studies carried out on the IEEE 33‐bus active distribution network verify the feasibility of the developed model and the high efficiency of the proposed solving strategy. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Low Voltage Ride-through and Research on the Control Strategy of Doubly-Fed Wind Power System

Deep Research in the problem of low voltage right through (LVRT) and over-current of rotor after the wind farm’s voltage dropped. Using the protection scheme of the energy dissipation type Crowbar protection circuit on the DC side can consume excess energy of the DC bus and ease the sharp rise of the DC bus voltage, to realize the low voltage ride-through of the wind power generation system. The simulation results show that after the grid voltage dropped, the Crowbar circuit timely cut off can make the rotor current decay rapidly, and ensure the stability of the wind turbine and wind power generation system. And through the theoretical calculation to make sure the range of the optimal resistance of the Crowbar circuit, and then pick out the several average sample value from this range to carry out simulation analysis, which has practical value and guiding significance.

A novel geometric pattern-based approach to maximize power output of a wind farm

The placement of wind turbines is crucial for a wind farm because the power generation of wind turbine is greatly affected by the wake effect produced by the upstream turbines. The optimum placement of wind turbines in a wind farm will give the maximum total power output. The effective methodology is imperative to place turbines in such a way that effect of the wake is minimum on a performance of turbines and has a proper utilization of the wind farm area. The present study proposes a novel approach based on the geometrical pattern-inspired placement methodology to locate wind turbines and maximize the power output of a wind farm. In the proposed approach, various geometrical patterns made from circle, hexagon, pentagon and triangle are considered for the numerical investigation. Further, wind behavior is modeled for uniform and variable wind speed from all directions. The present approach is also experimented numerically with and without land availability constraints. Heat transfer search algorithm is used to solve the wind farm layout optimization problem with the proposed approach and the results are compared with other approaches available in the literature. Results show that the proposed geometrical pattern-based approach produces the higher power generation (~4–8%) compared to other approaches for the variable wind speed scenario. In the case of land availability constraints, about 4% higher power generation compared to the grid-based approach is achieved. In order to place turbines with an optimum performance of a wind farm, the present approach can be helpful to wind farm developers.

Turbine Stability-Constrained Available Wind Power of Variable Speed Wind Turbines for Active Power Control

The active power control (APC) of variable-speed wind turbines (VSWT) is increasingly required to support the power system operation and control. Besides control strategies, the power reference also exerts a significant influence upon APC performance. Due to the VSWT instability, the optimistic reference which is usually determined according to the conventional available wind power (AWP) based on maximum power point, cannot be sustainably maintained over the dispatch period. This may results in frequent interruption of power reference tracking. On the other hand, the conservative reference will easily lead to excessive pitch regulation. In this letter, the turbine stability-constrained available wind power is defined and analyzed to sustain the power generation of scheduled wind turbines at a maximum level. Simulation results show that the VSWT dispatched according to the proposed AWP can maintain stable power generation with less pitch action and therefore better support secure and economic power system operations.

Layout optimization of a wind farm to maximize the power output using enhanced teaching learning based optimization technique

The global warming is a major concern in the present era that arises a need of cleaner production of energy. The wind energy is a major source of contribution for such clean energy demands. The Wind farm layout optimization (WFLO) problem deals with the optimum placement of wind turbines in a wind farm so as to maximize the total power output with minimum cost of energy. The placement of turbines is crucial for a wind farm because the power generation of wind turbine decreases if it is in the wake effect produced by the upstream turbines. So, WFLO problem is a challenging combinatorial optimization problem for which many direct search and local optimization method fails to attend the global optimum solution. The Meta-heuristic method often provides the effective solution for such problems in terms of convergence and the quality of the solution. In this work two, different metaheuristics algorithms are proposed to solve WFLO problem. These algorithms are developed by incorporating changes in the basic Teaching-learning based optimization (TLBO) algorithm. The proposed algorithms eliminate the limitations of basic TLBO algorithm to enhance its exploration and exploitation by incorporating effective search techniques. The implementations of the proposed algorithm are effective to optimize the position of wind turbines in a wind farm to maximize the expected power output of a wind farm with a minimum investment cost. The proposed algorithm is investigated for WFLO problem and a set of 10 challenging real life benchmark problems. The numerical results indicate that the proposed method is an effective technique to solve the WFLO problem compared to its basic algorithm and other state of the art methods. The optimum design of the wind farm results in the economical utilization of the wind resource and leads to clean energy production.