Renewable Energy Resources and Technologies
Farhad Amiri; Mohammad Hassan Moradi
Abstract
In the power system, frequency stability is critical. The wind turbine oscillates (depending on the wind speed) and is of low inertia. Thus, wind turbines face the issue of power system frequency stability. Since the power system's resources are interconnected via communication networks, the presence ...
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In the power system, frequency stability is critical. The wind turbine oscillates (depending on the wind speed) and is of low inertia. Thus, wind turbines face the issue of power system frequency stability. Since the power system's resources are interconnected via communication networks, the presence of time delay also affects the frequency stability of the power system. When a disturbance occurs in the power system due to load or distributed generation sources (wind turbine), it leads to frequency deviations in the power system, exhibiting low damping speed. Although large conventional generators in the power system provide sufficient inertia and reduce frequency deviation, the damping speed of frequency fluctuations is slow, which may be due to time delays between power system resources. In this paper, virtual damping (a proposed method) is used to accelerate the damping of frequency deviations caused by load disturbances, distributed generation source disturbances, and the time delay between power system resources. The results of the proposed method are compared to those obtained using the conventional method in this field, demonstrating the superiority of the proposed method. The proposed method reduced frequency deviations in the power system caused by disturbances and time delays by 67 % (a 67 % improvement over existing methods in this field) and increased the damping speed of the frequency deviations by 62 % (a 62 % improvement over the methods used in this field).
Renewable Energy Resources and Technologies
Amir Hossein Zare; Esmail Mahmoodi; Mohsen Boojari; Ali Sarreshtehdari
Abstract
Significant growth of the wind power market has led to a dramatic increase in the scale and capacity of wind turbines over the past decades. As these extreme-scale structures are expected to pose a wide range of challenges, an innovative concept which both lightens blade's mass and improves their aerodynamic ...
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Significant growth of the wind power market has led to a dramatic increase in the scale and capacity of wind turbines over the past decades. As these extreme-scale structures are expected to pose a wide range of challenges, an innovative concept which both lightens blade's mass and improves their aerodynamic performance, is vital for the future of rotor's design. In the present study, modeling and evaluating of an innovative pre-aligned rotor design based on SANDIA SNL100-00 wind turbine blade were accomplished. To evaluate the aerodynamic performance of the proposed rotor, CFD simulation was used as a well-developed technique in fluid mechanic. In the new rotor design, the swept area was increased using an equal blade length and the blade sections were more appropriately aligned with the wind flow compared to the reference model. This enhancement attained due to transferring the bending position from the root to a certain point alongside the length of blade. According to simulation assessments, this modification led to the overall improvement of main performance parameters in terms of the mean power and the applied torque on the blades. The simulation revealed that the novel concept is capable of increasing the mean power coefficient by 13.21 % compared to the conventional rotor designs. Analysis of the axial induction in front of the rotor plane displayed a greater drop in the flow velocity streaming up to the rotor, which could lead to have a more efficient configuration for harnessing the upcoming wind's power.
Renewable Energy Resources and Technologies
Ali Ebadi; Ali Akbar Abdoos; Mohammad Ebrahim Moazzen; Sayyed Asghar Gholamian
Abstract
Nowadays, the Permanent Magnet (PM) generator has become an instrumental tool for wind power generation due to its high performance. In this study, an optimal design is established to provide a cost-effective multiphase outer-rotor PM wind generator (OR-PMWG). The cost of the generation system (generator ...
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Nowadays, the Permanent Magnet (PM) generator has become an instrumental tool for wind power generation due to its high performance. In this study, an optimal design is established to provide a cost-effective multiphase outer-rotor PM wind generator (OR-PMWG). The cost of the generation system (generator and power converter) as well as the annual energy output must be optimized to ensure cost-effective PM wind generation. In fact, the main novelty of this paper lies in the presentation of an accurate model of OR-PMWG and the investigation of the design variables affecting annual energy output and the generation system cost (GSC). In this respect, a multi-objective framework is presented to make satisfactory agreement among all objectives. At first, the main optimal design objectives namely generation system cost and annual energy output are optimized separately and then, a multi-objective optimization is established, in which all the objectives are considered simultaneously. In order to tackle these optimization problems, Genetic Algorithm (GA) is adopted herein to determine the design variables. It is also shown that simultaneous optimization with 71.39 (MWh) AEO and 2651.51 (US$) GSC leads to a more optimal design for a PM wind generation system. In addition, the effectiveness of the presented optimal design is demonstrated by making a comparison between a prototype outer-rotor PM wind generator and the theoretical counterpart. Finally, a finite element analysis (FEA) is carried out for the validation of the outcomes obtained from the proposed optimal design.
Renewable Energy Resources and Technologies
Ehsan Hosseini; Neda Behzadfar; Mahnaz Hashemi; Majid Moazzami; Majid Dehghani
Abstract
Wind turbines can be controlled by controlling the generator speed and adjusting the blade angle and the total rotation of a turbine. Wind energy is one of the main types of renewable energy and is geographically extensive, scattered and decentralized and is almost always available. Pitch angle control ...
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Wind turbines can be controlled by controlling the generator speed and adjusting the blade angle and the total rotation of a turbine. Wind energy is one of the main types of renewable energy and is geographically extensive, scattered and decentralized and is almost always available. Pitch angle control in wind turbines with Doubly Fed Induction Generator (DFIG) has a direct impact on the dynamic performance and oscillations of the power system. Due to continuous changes in wind speed, wind turbines have a multivariate nonlinear system. The purpose of this study is to design a pitch angle controller based on fuzzy logic. According to the proposed method, nonlinear system parameters are automatically adjusted and power and speed fluctuations are reduced. The wind density is observed by the fuzzy controller and the blade angle is adjusted to obtain appropriate power for the system. Therefore, the pressure on the shaft and the dynamics of the turbine are reduced and the output is improved, especially in windy areas. Finally, the studied system is simulated using Simulink in MATLAB and the output improvement with the fuzzy controller is shown in the simulation results compared to the PI controller. Fuzzy control with the lowest cost is used to control the blade angle in a wind turbine. Also, in this method, the angle is adjusted automatically and it adapts to the system in such a way that the input power to the turbine is limited. Compared to the PI controller, by calculating different parameters, the power quality for fuzzy controller is enhanced from 2.941 % to 4.762 % for wind with an average speed of 12 meters per second.
Renewable Energy Resources and Technologies
Alireza Maheri; I Kade Wiratama; Terence Macquart
Abstract
The effectiveness of trailing-edge flaps and microtabs in damping 1P-3P loads has been proven through a series of research work during the past decade. This paper presents the results of an investigation into the effectiveness of these devices in power enhancement and power control for responding to ...
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The effectiveness of trailing-edge flaps and microtabs in damping 1P-3P loads has been proven through a series of research work during the past decade. This paper presents the results of an investigation into the effectiveness of these devices in power enhancement and power control for responding to the issue of where these devices can be used with dual function of load and power control on a medium size turbine. The 300 kW-AWT27 wind turbine is used as the base wind turbine and the effects of adding trailing-edge flaps and string of microtabs of different lengths positioned at different span locations on the aerodynamic performance of the rotor are studied. In each case, the wind turbine simulator WTSim is used to obtain the aerodynamic performance measures. In the next step, the original blade twist is redesigned to ensure that the blade is optimized upon the addition of these active flow controllers. It is found that blades equipped with flaps can increase the annual average power and reduce the blade loading at the same time for constant speed and variable speed generators. Power enhancement is more visible on constant speed rotors, while load reduction is more significant on variable speed rotors. To achieve constant speed rotors, an average power enhancement of around 12 % is achieved for a flap of size 25 % of the blade span located at about 72 % of the blade span. Microtabs are less effective in power control and can improve the produced power only by a few percentage points.
Renewable Energy Resources and Technologies
Sajad Saberi; Behrooz Rezaie
Abstract
This paper presents a sensorless speed control algorithm based on Finite Control Set Model Predictive Control (FCS-MPC) for Permanent Magnet Synchronous Motor (PMSM) fed by a 3-level Neutral-Point Clamped (NPC) converter. The proposed scheme uses an anti-windup Proportional-Integral (PI) controller concept ...
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This paper presents a sensorless speed control algorithm based on Finite Control Set Model Predictive Control (FCS-MPC) for Permanent Magnet Synchronous Motor (PMSM) fed by a 3-level Neutral-Point Clamped (NPC) converter. The proposed scheme uses an anti-windup Proportional-Integral (PI) controller concept to generate the reference electromagnetic torque using the error of speed. Then, FCS-MPC uses this torque reference and other parameters such as a current limitation, neutral point voltage unbalance, and switching frequency to control the converter gate signals. Also, an Adaptive Nonsingular Fast Terminal Sliding Mode Observer (ANFTSMO) was employed to estimate rotor position precisely in positive (clockwise) and negative (counterclockwise) speed to eliminate the encoder. The proposed algorithm has fast dynamics and low steady-state error. Moreover, torque fluctuation and current distortion reduced compared with Space Vector Pulse Width Modulation (SVPWM) based speed control and Direct Predictive Speed Control (DPSC). Simulation results using MATLAB/SIMULINKÒ demonstrate the performance of the proposed scheme.
Renewable Energy Resources and Technologies
Hossein Dastres; Ali Mohammadi; Behrooz Rezaie
Abstract
This paper deals with the problem of maximizing the extracted power from a wind turbine in the presence of model uncertainties and input saturation. An adaptive second-order integral terminal sliding mode speed control method is utilized to address this problem. The presented method benefits from the ...
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This paper deals with the problem of maximizing the extracted power from a wind turbine in the presence of model uncertainties and input saturation. An adaptive second-order integral terminal sliding mode speed control method is utilized to address this problem. The presented method benefits from the advantages of several control techniques, i.e., adaptability, robustness, finite-time convergence, and the capability of coping with the input saturation. The robust nature of the designed controller causes its high performance in facing the uncertainties in the wind turbine model. In this paper, to compensate for the effect of input saturation, an auxiliary dynamic variable is added to the tracking error and also an adaptation law is designed so that the finite-time convergence of the closed-loop system can be achieved. Moreover, to reduce the mechanical stresses which are the result of the chattering phenomenon, a second-order sliding surface is employed. The finite-time convergence of the designed controller has been proven by the Lyapunov stability theorem in which the finite-time convergence of the tracking error to zero is guaranteed. Finally, to illustrate the effectiveness and satisfactory performance of the proposed controller, two comparative simulations are carried out. The results of this comparison show that the proposed controller has less error to track the optimal speed and when the model uncertainties and input saturation occur in the wind turbine system, the proposed controller is almost 3 % more efficient than the existing controllers.
Renewable Energy Resources and Technologies
Mahdi Shahmari; Payam Zarafshan; Shahriar Kouravand; Morteza Khashehchi
Abstract
Renewable energies as a clean replacement resource of fossil fuels have many advantages, among which wind has the potential to be the very applicable source in the world. To use wind energy, two kinds of turbines have been developed; the Vertical Axis Wind Turbine (VAWT) and Horizontal Axis Wind Turbine ...
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Renewable energies as a clean replacement resource of fossil fuels have many advantages, among which wind has the potential to be the very applicable source in the world. To use wind energy, two kinds of turbines have been developed; the Vertical Axis Wind Turbine (VAWT) and Horizontal Axis Wind Turbine (HAWT). In small scale applications, using a VAWT has some advantages such as low cost and noise, simple mechanism, and the low sensitivity to the wind direction. In this paper, the design and analysis of a combined wind turbine, consist of the Savonius-Darrieus rotor, are performed to use in irrigation applications. To predict the output power, a series of experiments were conducted using the Computational Fluid Dynamics (CFD) method. For this purpose, ANSYS fluent and Q-Blade software programs are used. To design the rotor performance, NACA symmetric airfoils are considered. Next, this combined turbine was made and experimental tests were performed. Finally, the output power is computed and so, the water flow rate for irrigation purposes such as water pumping is obtained. The results indicate that the self-starting of the turbine is improved using the considered design. This could be useful in regions with low wind speed.
Renewable Energy Resources and Technologies
Saeed Karimian Aliabadi; Sepehr Rasekh
Abstract
In this study, an unsteady aerodynamic simulation is performed to realize the influences of platform surge motion on the aerodynamic performance of a high capacity offshore floating wind turbine. A dynamic model with pitch angle control system is utilized to propose a more realistic model of wind turbine ...
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In this study, an unsteady aerodynamic simulation is performed to realize the influences of platform surge motion on the aerodynamic performance of a high capacity offshore floating wind turbine. A dynamic model with pitch angle control system is utilized to propose a more realistic model of wind turbine and also achieve the rated condition of the rotor. The transient effect of platform surge motion on power coefficient, thrust coefficient and blade pitch angle also is investigated. The 5 MW NREL wind turbine is selected for the simulations. The unsteady aerodynamic model contains unsteady blade element momentum method, dynamic stall and dynamic inflow models. The in-home aerodynamic code and the control system model are implemented in MATLAB/SIMULINK software. It is revealed that reduction in mean power coefficient at tip speed ratios less that 7 is expected by amount of 12-15 % at surge amplitude of 2m and frequency of 0.1 Hz. For high tip speed ratios, the trend is reverse with respect to fixed-platform case. The mean thrust coefficient is also reduced for many tip speed ratios with maximum loss of 32 %. The mean blade control pitch angle is increased due to the surge motion. Since the influence of changing amplitude and frequency of disturbances depends on the tip speed ratio, therefore the special bound of this parameter is being proposed.
