The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Zhe Chen - One of the best experts on this subject based on the ideXlab platform.
-
improving power smoothing and performance of pitch angle system for above Rated Speed range in Wind power systems
Iet Generation Transmission & Distribution, 2019Co-Authors: Mehrdad Gholami, Seyed Hamid Fathi, Jafar Milimonfared, Zhe ChenAbstract:This study presents a new simple control strategy for direct driven permanent magnet synchronous generator Wind turbines, using no Wind Speed sensor. It is shown that the fluctuation in output power, not only exists at below the Rated Wind Speed, but also appears in above the Rated Speed region. Therefore, it employs power-smoothing strategies within a wide range of Wind Speeds and provides soft performance of the pitch angle system for above the Rated Speed range. In previous studies, power smoothing is mainly limited to the Wind Speeds below the Rated value, whereas, in this study, all operating Speed ranges of the turbine, including Wind Speeds above the Rated value, are considered. Fluctuation in the output power for above the Rated Speed is analysed and it is shown that there is a significant level of fluctuation in the output power. Therefore, a new strategy is proposed to have more power smoothing as well as having soft performance of pitch angle system for above the Rated Speed region. The performance of the proposed strategy is evaluated by MATLAB/ Simulink simulation and its validity and effectiveness are verified.
-
Proportional resonant individual pitch control for mitigation of Wind turbines loads
IET Renewable Power Generation, 2013Co-Authors: Yunqian Zhang, Ming Cheng, Zhe ChenAbstract:This study addresses the mitigation of Wind turbine loads and fatigue such as blade bending moments, tilt and yaw moments etc. Currently, the Wind turbine blades are normally controlled to turn collectively to limit the excess of Wind power above Rated Wind Speed conditions without any load attenuation. The individual pitch control (IPC) is a promising way to reduce the Wind turbine loads. This study presents a proportional resonant (PR) IPC, which does not need the measurement of blade azimuth angle and multiple complex Coleman transformations between rotational coordinate frame and stationary coordinate frame. The new strategy can attenuate the 1p and higher harmonics on the Wind turbine blades as well as 3p on the hub without any filters. The Wind turbine code fatigue, aerodynamics, structures and turbulence is applied to a doubly fed induction generator-based Wind power generation system. The simulations are performed on the National Renewable Energy Laboratory 1.5MW upWind reference Wind turbine model. The simulation results are presented and discussed to demonstrate the capability and effectiveness of the proposed PR IPC method.
-
design optimization and site matching of direct drive permanent magnet Wind power generator systems
Renewable Energy, 2009Co-Authors: Zhe ChenAbstract:This paper investigates the possible site matching of the direct-drive Wind turbine concepts based on the electromagnetic design optimization of permanent magnet (PM) generator systems. Firstly, the analytical models of a three-phase radial-flux PM generator with a back-to-back power converter are presented. The optimum design models of direct-drive PM Wind generation system are developed with an improved genetic algorithm, and a 500-kW direct-drive PM generator for the minimal generator active material cost is compared to demonstrate the effectiveness of the design optimization. Forty-five PM generator systems, the combinations of five Rated rotor Speeds in the range of 10–30rpm and nine power ratings from 100kW to 10MW, are optimally designed, respectively. The optimum results are compared graphically in terms of the generator design indexes. Next, according to the design principle of the maximum Wind energy capture, the rotor diameter and the Rated Wind Speed of a direct-drive Wind turbine with the optimum PM generator are determined. The annual energy output (AEO) is also presented using the Weibull density function. Finally, the maximum AEO per cost (AEOPC) of the optimized Wind generator systems is evaluated at eight potential sites with annual mean Wind Speeds in the range of 3–10m/s, respectively. These results have shown the suitable designs for the optimum site matching of the investigated PM generator systems.
-
optimal power control strategy of maximizing Wind energy tracking and conversion for vscf doubly fed induction generator system
International Power Electronics and Motion Control Conference, 2006Co-Authors: Hui Li, Zhe Chen, John Kim PedersenAbstract:This paper focuses on the development of maximum Wind power extraction strategies for variable Speed constant frequency (VSCF) grid-connected Wind power generation systems with a doubly fed induction generator (DFIG). A new optimal control method is proposed by controlling the generator stator active and reactive power, which is based on the condition of the system operation for not only the extracted maximum power of the Wind turbine below the Rated Wind Speed but also the higher generator efficiency. Based on the DFIG mathematical models, the optimal stator reactive power value is derived for minimal machine copper losses. According to Wind turbine power characteristics and generator power flow equations, the optimal stator active power reference value is also obtained for capturing maximal output power from Wind turbines. A dual-passage excitation control strategy is applied to control the active and reactive power independently. Detailed simulation results have confirmed the feasibility and performance of the optimal control strategy.
Ali Mostafaeipour - One of the best experts on this subject based on the ideXlab platform.
-
a new semi empirical Wind turbine capacity factor for maximizing annual electricity and hydrogen production
International Journal of Hydrogen Energy, 2020Co-Authors: Ahmad Sedaghat, Ali Mostafaeipour, Mostafa Rezaei, Mehdi Jahangiri, Amirreza MehrabiAbstract:Abstract The capacity factor is an important Wind turbine parameter which is ratio of average output electrical power to Rated electrical power of the Wind turbine. Another main factor, the AEP, the annual energy production, can be determined using Wind characteristics and Wind turbine performance. Lower Rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a Wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a Rated Wind Speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor is expressed as ratio of the AEP for Wind turbine to yearly Wind energy delivered by mean Wind Speed at the rotor swept area. The methodology is demonstRated using the empirical efficiency curve of Vestas-80 2 MW turbine and the Weibull probability density function. Simultaneous use of the primary and the secondary capacity factors are discussed for maximizing electrical energy and hence hydrogen production for different Wind classes and economic feasibility are scrutinized in several Wind stations in Kuwait.
-
a new strategy for Wind turbine selection using optimization based on Rated Wind Speed
Energy Procedia, 2019Co-Authors: Ahmad Sedaghat, Fadi Alkhatib, Armin Eilaghi, Mohamad Sabati, Leila Borvayeh, Ali MostafaeipourAbstract:Abstract It is generally anticipated that larger Wind turbines result in better electrical power generation in more efficient and economical manner. However, the question remains is that how large a Wind turbine is the optimum size for a selected Wind site? To answer this, three important objective functions, the levelized cost of electricity (LCOE), the capacity factor (CF) and a normalized annual energy production (AEP) are optimized versus the Rated Wind Speed. Four empirical power curve models for large Wind turbines and Weibull Wind distribution are investigated to produce a Pareto front within range of practical Wind conditions. It is observed that the optimized values of the objective functions are merely dependant on the Weibull shape factor, k. Also, the optimum Rated Wind Speed is a linear function of the Weibull scale factor, c. Therefore, it is concluded that, there are limits for the optimum Rated Wind power and the costs. Consequently within the Pareto front, the lower Rated power Wind turbines may be selected to reduce LCOE albeit the higher Rated power Wind turbines may be adopted to produce higher AEP and CF.
-
determination of Rated Wind Speed for maximum annual energy production of variable Speed Wind turbines
Applied Energy, 2017Co-Authors: Ahmad Sedaghat, Arash Hassanzadeh, J Jamali, Ali MostafaeipourAbstract:Rated Wind Speed is recognized as one of the key design factors affecting the overall power production of a Wind turbine. No formulation is found in literature to relate the Rated Wind Speed to the Wind turbine power curves and the annual energy production (AEP). This paper aims to formulate the suitable Rated Wind Speed for variable Speed Wind turbines continuously operating at maximum power coefficient for maximizing AEP. A capacity value is introduced which relates AEP to an integral function of the Rated Wind Speed using Weibull distribution of Wind Speeds and the constant power coefficient of variable Speed Wind turbines. The capacity values are calculated and presented versus Rated Wind Speeds at different Wind classes and Weibull parameters. From the results, the suitable values for the Rated Wind Speeds for maximizing AEP are found which are considerably higher than normally used values and varied from 2 to 5 times of the annual mean Wind Speed. For instance, for the mean annual Wind Speed of 4m/s and the shape factors of k=1.2, 1.6, 2.0, 2.4, 2.8, 3.2, and 3.6, the converged Rated Wind Speeds are Vrate=20, 19, 14, 12, 10, 10, and 9m/s, respectively. On this basis, new charts for Rated Wind Speeds are introduced for selecting suitable Wind turbines for maximizing AEP. It is concluded that for some selected Wind turbines operating at lower Rated Wind Speeds, the AEP may fall below about 43% of actual achievable AEP when employing higher recommended Rated Wind Speeds. Hence, it is shown that selecting the right Rated Wind Speed Wind turbines has great impact on overall energy production of a Wind site.
Ahmad Sedaghat - One of the best experts on this subject based on the ideXlab platform.
-
a new semi empirical Wind turbine capacity factor for maximizing annual electricity and hydrogen production
International Journal of Hydrogen Energy, 2020Co-Authors: Ahmad Sedaghat, Ali Mostafaeipour, Mostafa Rezaei, Mehdi Jahangiri, Amirreza MehrabiAbstract:Abstract The capacity factor is an important Wind turbine parameter which is ratio of average output electrical power to Rated electrical power of the Wind turbine. Another main factor, the AEP, the annual energy production, can be determined using Wind characteristics and Wind turbine performance. Lower Rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a Wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a Rated Wind Speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor is expressed as ratio of the AEP for Wind turbine to yearly Wind energy delivered by mean Wind Speed at the rotor swept area. The methodology is demonstRated using the empirical efficiency curve of Vestas-80 2 MW turbine and the Weibull probability density function. Simultaneous use of the primary and the secondary capacity factors are discussed for maximizing electrical energy and hence hydrogen production for different Wind classes and economic feasibility are scrutinized in several Wind stations in Kuwait.
-
a new strategy for Wind turbine selection using optimization based on Rated Wind Speed
Energy Procedia, 2019Co-Authors: Ahmad Sedaghat, Fadi Alkhatib, Armin Eilaghi, Mohamad Sabati, Leila Borvayeh, Ali MostafaeipourAbstract:Abstract It is generally anticipated that larger Wind turbines result in better electrical power generation in more efficient and economical manner. However, the question remains is that how large a Wind turbine is the optimum size for a selected Wind site? To answer this, three important objective functions, the levelized cost of electricity (LCOE), the capacity factor (CF) and a normalized annual energy production (AEP) are optimized versus the Rated Wind Speed. Four empirical power curve models for large Wind turbines and Weibull Wind distribution are investigated to produce a Pareto front within range of practical Wind conditions. It is observed that the optimized values of the objective functions are merely dependant on the Weibull shape factor, k. Also, the optimum Rated Wind Speed is a linear function of the Weibull scale factor, c. Therefore, it is concluded that, there are limits for the optimum Rated Wind power and the costs. Consequently within the Pareto front, the lower Rated power Wind turbines may be selected to reduce LCOE albeit the higher Rated power Wind turbines may be adopted to produce higher AEP and CF.
-
determination of Rated Wind Speed for maximum annual energy production of variable Speed Wind turbines
Applied Energy, 2017Co-Authors: Ahmad Sedaghat, Arash Hassanzadeh, J Jamali, Ali MostafaeipourAbstract:Rated Wind Speed is recognized as one of the key design factors affecting the overall power production of a Wind turbine. No formulation is found in literature to relate the Rated Wind Speed to the Wind turbine power curves and the annual energy production (AEP). This paper aims to formulate the suitable Rated Wind Speed for variable Speed Wind turbines continuously operating at maximum power coefficient for maximizing AEP. A capacity value is introduced which relates AEP to an integral function of the Rated Wind Speed using Weibull distribution of Wind Speeds and the constant power coefficient of variable Speed Wind turbines. The capacity values are calculated and presented versus Rated Wind Speeds at different Wind classes and Weibull parameters. From the results, the suitable values for the Rated Wind Speeds for maximizing AEP are found which are considerably higher than normally used values and varied from 2 to 5 times of the annual mean Wind Speed. For instance, for the mean annual Wind Speed of 4m/s and the shape factors of k=1.2, 1.6, 2.0, 2.4, 2.8, 3.2, and 3.6, the converged Rated Wind Speeds are Vrate=20, 19, 14, 12, 10, 10, and 9m/s, respectively. On this basis, new charts for Rated Wind Speeds are introduced for selecting suitable Wind turbines for maximizing AEP. It is concluded that for some selected Wind turbines operating at lower Rated Wind Speeds, the AEP may fall below about 43% of actual achievable AEP when employing higher recommended Rated Wind Speeds. Hence, it is shown that selecting the right Rated Wind Speed Wind turbines has great impact on overall energy production of a Wind site.
-
Rated Wind Speed reality or myth for optimization in design of Wind turbines
International Conference on Ecological Vehicles and Renewable Energies, 2016Co-Authors: Ahmad Sedaghat, Mohamed Gaith, Khalil Khanafer, Ehab Hussein BanihaniAbstract:The rotor design procedure of Wind turbines starts first with adopting a Rated output power and a Rated Wind Speed. There is lack of modelling to determine an optimized Rated Wind Speed and no evidences are observed to suggest the best Rated Wind Speed to produce maximum output power annually. For example in the market of small Wind turbines, it is frequently observed that the Rated Wind Speed is taken from small value of 8 m/s to large value of 20 m/s. To examine overall performance of these Wind turbines, it is required to develop mathematical models to relate the annual power production of the Wind turbines to the given Rated Wind Speeds. By examining power curves of some small European Wind turbines from 100 to 900 Watt with constant Speed generators, a simplified mathematical model for power curves is introduced and combined with Weibull distribution of Wind Speeds. Results of the model based on a capacity factor are presented versus the Rated Wind Speed using Wind characteristics of an optional region. It is observed that between the cut-in and cut-out Wind Speeds, there is an optimum Rated Wind Speed above which the annual output power production of the Wind turbine remains unchanged.
Debashisha Jena - One of the best experts on this subject based on the ideXlab platform.
-
validation of an integral sliding mode control for optimal control of a three blade variable Speed variable pitch Wind turbine
International Journal of Electrical Power & Energy Systems, 2015Co-Authors: R Saravanakumar, Debashisha JenaAbstract:Abstract Reduction in cost of Wind energy requires most efficient control technology which can able to extract optimum power from the Wind. This paper mainly focuses on the control of variable Speed variable pitch Wind turbine (VSVPWT) for maximization of extracted power at below Rated Wind Speed (region 2) and regulation of extracted power when operating at above Rated Wind Speed (region 3). To extract maximum power at below Rated Wind Speed torque control is used whereas to regulate Rated power at above Rated Wind Speed pitch control is used. In this paper a nonlinear control i.e. integral sliding mode control (ISMC) is proposed for region 2 whereas a conventional proportional–integral (PI) control is adapted for region 3 of a VSVPWT. The proposed controller is combined with modified Newton Raphson (MNR) Wind Speed estimator to estimate the Wind Speed. The stability of the proposed ISMC is analyzed using Lyapunov stability criterion and the control law is derived for region 2 which is also adapted for the transition period between region 2 and region 3 (region 2.5). The dynamic simulations are tested with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence) Wind turbine (WT). The simulation results of ISMC are presented and the control performance is compared with conventional SMC and existing controllers such as aerodynamic torque feed forward control (ATF) and Indirect Speed control (ISC). It is seen that especially in region 2.5, ISMC gives better performance compared to all other controllers.
-
control of variable Speed variable pitch Wind turbine at above and below Rated Wind Speed
Journal of Wind Energy, 2014Co-Authors: Saravanakumar Rajendran, Debashisha JenaAbstract:The paper presents a nonlinear approach to Wind turbine (WT) using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying Wind Speed. In this work, a combination of linear and nonlinear controllers is adapted to variable Speed variable pitch Wind turbines (VSVPWT) system. The major operating regions of the WT are below (region 2) and above Rated (region 3) Wind Speed. In these regions, generator torque control (region 2) and pitch control (region 3) are used. The controllers in WT are tested for below and above Rated Wind Speed for step and vertical Wind Speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence) WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC) and integral sliding mode control (ISMC), have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization.
David T Westwick - One of the best experts on this subject based on the ideXlab platform.
-
multiple model multiple input multiple output predictive control for variable Speed variable pitch Wind energy conversion systems
Iet Renewable Power Generation, 2011Co-Authors: Mostafa Soliman, O P Malik, David T WestwickAbstract:A multivariable control strategy based on model predictive control techniques for the control of variable-Speed variable pitch Wind energy conversion systems (WECSs) in the above-Rated Wind Speed zone is proposed. Pitch angle and generator torque are controlled simultaneously to provide optimal regulation of the geneRated power and the generator Speed while minimising torsional torque fluctuations in the drive train and pitch actuator activity. This has the effect of improving the power quality of the electrical power geneRated by the WECS and increasing the life time of the mechanical parts of the system. Furthermore, safe and acceptable operation of the system is guaranteed by incorporating most of the constraints on the physical variables of the WECS in the controller design. In order to cope with the non-linearity in the WECS and the continuous variation in the operating point, a multiple model predictive controller is suggested to provide near optimal performance within the whole operating region.
