基于粒子群优化算法的风力机塔架结构优化设计

为了降低风力机塔架成本以及提高塔架的结构性能,编制粒子群优化算法程序,在算法程序中嵌入有限元方法,选取塔架壁厚、塔底直径及塔顶直径为设计变量,以强度、刚度、振动性能及稳定性为约束条件,建立了以质量最轻为目标函数的塔架优化数学模型,对某1.5 MW风力机塔架结构进行了优化设计。结果表明,优化后塔架的结构性能得到了改善,塔架变形对壁厚变化较为敏感,塔架质量减少了16.3%,说明了计算模型的有效性,可为同类塔架的设计提供参考。     

考虑连接段厚度影响的风力机组合塔架优化设计*

钢-混组合塔架是低风速地区风力机支撑结构的主要型式之一,连接段对结构的性能有重要影响,组合塔架结构设计直接影响风力机的安全与建设成本。为改善塔架的结构性能以及降低塔架造价,构建了以各塔段外径、壁厚、连接段厚度和混凝土段高度等关键几何尺寸为设计变量,以塔架的固有频率、应力、位移和稳定性等关键性态指标为约束条件,以塔架成本为目标函数的优化设计数学模型。利用模型对某3 MW风力机组合塔架进行优化设计。结果表明：优化方案的塔架总成本减少了15.7%,塔架的整体结构性能得到一定改善;混凝土段高度为塔架总高度的62%时总成本最低;考虑连接段厚度的优化模型能有效调整连接段的受力性能,有利于提高塔架整体优化的效果。考虑组合塔架连接段厚度的优化设计可为同类塔架的设计提供参考。     

风力机混凝土塔架最小成本优化设计

讨论有粘结预应力混凝土风力机塔架的结构计算,并从提高经济性和方便施工角度,利用自动分组遗传算法(AGGA)研究混凝土塔架优化设计问题。首先根据风力机塔架受力特点,提出混凝土塔架承载力和正常使用极限状态的设计要求,并参考国内外现行规范,给出计算这些设计要求的方法。在此基础上,建立以塔架最小建造成本为目标,考虑两种极限状态下多项设计要求和反映施工复杂程度的设计变量分组要求的优化模型。AGGA求解该优化问题,获得满足要求的最小成本设计。36 m混凝土塔架算例可表明优化方法的效果。     

随机风载荷下大型风力机叶片/机舱/塔架耦合动力学分析

由于风力机叶片所受风力来流的随机性和风力机结构的复杂性,大型风力机在随机风载荷下的动力学行为分析一直是风电行业急需解决的难题之一。利用MATLAB/Simulink对随机风速进行了模拟,通过柔性多体动力学方法建立了符合实际的风力机叶片/机舱/塔架耦合动力学方程。在随机风载荷下对目前国内1.5 MW主流风力机的叶片、塔架的动力学行为进行了实例分析,得到了10 min时序随机风载下的叶片挥舞位移、速度历程和塔架的位移、速度历程。分析结果表明,在随机风载下,风力机启动时叶片、塔架振动较为剧烈,随时间的增加叶片、塔架振动幅度逐渐减小,振动速度也呈减小趋势。该研究结果为我国风力机设计理论的完善和工程实践奠定了一定的基础。     

风力机塔架动力学有限元分析系统

基于有限单元法,利用VC开发了ANSYS平台下的风力机塔架有限元建模和动力学分析系统.在VC程序中使用APDL语言封装ANSYS,由系统生成的APDL数据文件直接驱动ANSYS进行塔架的动力学性能分析.通过和风力机全系统载荷分析及优化设计软件的集成,实现了从风场计算、气动载荷计算到结构动力学分析的一体化.计算结果的对比分析表明,该软件的计算模型正确,能很好地用于风力机总体设计过程中对塔架结构的动力学分析.     

水平轴风力机结构动力响应分析

考虑水平轴风力机叶片和塔架的结构柔性,基于模态分析方法,建立了风力机叶片和塔架的耦合动力学模型来模拟整个系统的动态行为.应用线性加速方法,实现了结构动力响应的数值解法.利用分析模型对一台1.25MW风力机在稳态风作用下的结构动力响应进行了计算,计算结果显示所建立的模型能正确反映外部激励对结构变形及载荷的影响.此外,从计算结果可看出大型风力机的柔性结构在工作过程中变形很大;在进行载荷计算时考虑前二阶模态可得到较合理的计算结果.     

基于均匀设计的风力机塔架结构参数优化研究

针对大型水平轴风力机塔架结构优化过程中主要影响要素不显著问题,以塔架塔顶与机舱底座连接处为研究对象,采用均匀设计法对连接处2要素(厚度、高度)进行U*9(92)静强度试验设计并进行数值仿真模拟。研究结果表明:塔架最大变形值与最大应力值与连接处2要素(厚度、高度)呈线性与双曲抛物面函数关系,其中高度变化较厚度变化对塔架的应力值变化影响更大,优化塔顶结构参数后比原塔架最大应力值减小0.89%,最大位移值减少0.22%,质量降低0.24%,该研究为风力机塔架多目标结构优化设计提供理论依据。     

风力机塔架在偏心载荷作用下的屈曲分析

以底部开门洞的大型风力机塔架为研究对象,研究了塔架在风轮、机舱荷载和塔架自身重力作用下引起的塔架屈曲问题的工程算法和有限元数值分析方法。对一个1.5MW风力机塔架在这类偏心荷载作用下的塔架屈曲值和屈曲模态进行了计算。计算结果表明:门洞的存在对薄壁筒体塔架的屈曲临界载荷有较大影响;相关标准提出的工程算法存在一定的局限性,需要结合有限元数值分析方法进行分析。在进行风力机塔架的设计时,该文计算结果具有一定的参考作用。     

水平轴风力机筒型塔架动态响应分析

为获得水平轴风力机塔架在时变载荷作用下的动态响应,将塔架简化成悬臂梁,利用二结点梁单元进行离散化建模,分析了塔架弯曲振动固有动力特性。在建立塔架结构动力学运动方程、计算塔架所受时变载荷的基础上,运用线性加速度法和模态叠加原理对风力机塔架的动态响应进行计算,编制了相应的计算机程序。以某1.0MW风力机塔架为例,获得了风力机在湍流风运行条件下塔架在仿真时间内的位移、速度和加速度,并与"GHBladed"软件的计算结果进行了比较,表明计算模型是可行的。     

风电预应力混凝土-钢混合塔架设计优化研究

风电预应力混凝土-钢混合塔架建设成本是结构选型的重要影响因素,该文基于改进粒子群算法与有限元方法提出一种优化方法,以2.5 MW风力机塔架为对象,取造价为目标函数,考虑上下塔段强度、刚度、稳定性、疲劳、塔顶位移以及结构自振频率等约束条件,实现了塔架截面及塔段高度优化。结果表明:风电混合塔架最不利荷载组合应取切出风速工况下水平气动力为第一可变荷载的荷载组合情况;钢塔段厚度对造价影响最大,其次为混凝土段高度与厚度;塔架的混凝土段高度约占塔架总高的75%时造价最低。     

Design optimization and site matching of direct-drive permanent magnet wind power generator systems

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 10–30 rpm and nine power ratings from 100 kW to 10 MW, 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 3–10 m/s, respectively. These results have shown the suitable designs for the optimum site matching of the investigated PM generator systems.     

A new constraint handling method for wind farm layout optimization with lands owned by different owners

For wind farm optimizations with lands belonging to different owners, the traditional penalty method is highly dependent on the type of wind farm land division. The application of the traditional method can be cumbersome if the divisions are complex. To overcome this disadvantage, a new method is proposed in this paper for the first time. Unlike the penalty method which requires the addition of penalizing term when evaluating the fitness function, it is achieved through repairing the infeasible solutions before fitness evaluation. To assess the effectiveness of the proposed method on the optimization of wind farm, the optimizing results of different methods are compared for three different types of wind farm division. Different wind scenarios are also incorporated during optimization which includes (i) constant wind speed and wind direction; (ii) various wind speed and wind direction; and (iii) the more realistic Weibull distribution. Results show that the performance of the new method varies for different land plots in the tested cases. Nevertheless, it is found that optimum or at least close to optimum results can be obtained with sequential land plot study using the new method for all cases. It is concluded that satisfactory results can be achieved using the proposed method. In addition, it has the advantage of flexibility in managing the wind farm design, which not only frees users to define the penalty parameter but without limitations on the wind farm division.     

A particle swarm optimization for wind energy control problem

The control problem of a wind turbine involves the determination of rotor speed and tip-speed ratio to maximize power and energy capture from the wind. The problem can be formulated as a nonlinear programming problem with the annual energy generation as the objective function. The wind speed distribution is modeled as the Weibull distribution. The Weibull shape and scale parameters are assigned to be stochastic in response to limited wind data and variability nature of the wind. It is proposed to apply particle swarm optimization to solve for optimum rotor speed under fixed-speed operation and optimum tip-speed ratio under variable-speed operation. The optimum rotor speed varies with the wind speed distribution, while the optimum tip-speed ratio does not depend on the wind speed distribution. It can be concluded from the simulation results that both the wind power and energy are more dependent of the Weibull scale parameter than the Weibull shape parameter. This implies that the wind power and energy are more dependent of the mean wind speed than the speed distribution.     

A comprehensive method for optimal power management and design of hybrid RES-based autonomous energy systems

The power management strategy (PMS) plays an important role in the optimum design and efficient utilization of hybrid energy systems. The power available from hybrid systems and the overall lifetime of system components are highly affected by PMS. This paper presents a novel method for the determination of the optimum PMS of hybrid energy systems including various generators and storage units. The PMS optimization is integrated with the sizing procedure of the hybrid system. The method is tested on a system with several widely used generators in off-grid systems, including wind turbines, PV panels, fuel cells, electrolyzers, hydrogen tanks, batteries, and diesel generators. The aim of the optimization problem is to simultaneously minimize the overall cost of the system, unmet load, and fuel emission considering the uncertainties associated with renewable energy sources (RES). These uncertainties are modeled by using various possible scenarios for wind speed and solar irradiation based on Weibull and Beta probability distribution functions (PDF), respectively. The differential evolution algorithm (DEA) accompanied with fuzzy technique is used to handle the mixed-integer nonlinear multi-objective optimization problem. The optimum solution, including design parameters of system components and the monthly PMS parameters adapting climatic changes during a year, are obtained. Considering operating limitations of system devices, the parameters characterize the priority and share of each storage component for serving the deficit energy or storing surplus energy both resulted from the mismatch of power between load and generation. In order to have efficient power exploitation from RES, the optimum monthly tilt angles of PV panels and the optimum tower height for wind turbines are calculated. Numerical results are compared with the results of optimal sizing assuming pre-defined PMS without using the proposed power management optimization method. The comparative results present the efficacy and capability of the proposed method for hybrid energy systems.     

Multi-objective optimization of the hybrid wind/solar/fuel cell distributed generation system using Hammersley Sequence Sampling

As the development of China's economy, environmental problems in China become more and more serious. Solar energy and wind energy are considered as ones of the best choices to solve the environmental problems in China and the hybrid wind/solar distributed generation (DG) system has received increasing attention recently. However, the instability and intermittency of the wind and solar energy throw a huge challenge on designing of the hybrid system. In order to ensure the continuous and stable power supply, optimal unit sizing of the hybrid wind/solar DG system should be taken into consideration in the design of the hybrid system. This paper establishes a multi-objective optimization framework based on cost, electricity efficiency and energy supply reliability models of the hybrid DG system, which is composed of wind, solar and fuel cell generation systems. Detailed models of each unit for the hybrid wind/solar/fuel cell system were established. Advanced ε-constraints method based on Hammersley Sequence Sampling was employed in the multi-objective optimization of the hybrid DG system. The approximate Pareto surface of the multi-objective optimization problems with a range of possible design solutions and a logical procedure for searching the global optimum solution for decision makers were presented. In this way, this work provided an efficient method for decision makers in the design of the hybrid wind/solar/fuel cell system.     

Simulation based size optimization of a PV/wind hybrid energy conversion system with battery storage under various load and auxiliary energy conditions

In this paper, size of a PV/wind integrated hybrid energy system with battery storage is optimized under various loads and unit cost of auxiliary energy sources. The optimization is completed by a simulation based optimization procedure, OptQuest, which integrates various heuristic methods. In the study, the main performance measure is the hybrid energy system cost. And the design parameters are PV size, wind turbine rotor swept area and the battery capacity. The case study is realized for Izmir Institute of Technology Campus Area, Urla, Turkey. The simulation model of the system is realized in ARENA 12.0, a commercial simulation software, and is optimized using the OptQuest tool in this software. Consequently, the optimum sizes of PV, wind turbine and battery capacity are obtained under various auxiliary energy unit costs and two different loads. The optimum results are confirmed using Loss of Load Probability (LLP) and autonomy analysis. And the investment costs are investigated how they are shared among those four energy sources at the optimum points.     

Developement and verification of a performance based optimal design software for wind turbine blades

In this research, we developed software for designing the optimum shape of multi-MW wind turbine blades and analyzing the performance, and it features aerodynamic shape design, performance analysis, pitch–torque analysis and shape optimization for wind turbine blades. In order to verify the accuracy of the performance analysis results of the software developed in this research, we chose the 5 MW blade, designed by NREL, as the comparison model and compared with the analysis results of well known commercial software (GH-Bladed). The calculated performance analysis results of GH-Bladed and our software were consistent in all values of C_P in all λ ranges. Also, to confirm applicability of the optimum design module, the optimum design of the new 5 MW blade was performed using the initial design data of the comparison model and found that solidity was smaller in our design even though it produced the same output and efficiency. Through optimization of blade design, efficiency increased by 1% while the thrust coefficient decreased by 7.5%.     

Optimized linearization of chord and twist angle profiles for fixed-pitch fixed-speed wind turbine blades

The chord and twist angle radial profiles of a fixed-pitch fixed-speed (FPFS) horizontal-axis wind turbine blade are based on a particular design wind speed and design tip speed ratio. Because the tip speed ratio varies with wind speed, the originally optimized chord and twist angle radial profiles for a preliminary blade design through optimum rotor theory do not necessarily provide the highest annual energy production (AEP) for the wind turbine on a specific site with known wind resources. This paper aims to demonstrate a novel optimal blade design method for an FPFS wind turbine through adopting linear radial profiles of the blade chord and twist angle and optimizing the slope of these two lines. The radial profiles of the blade chord and twist angle are linearized on a heuristic basis with fixed values at the blade tip and floating values at the blade root based on the preliminary blade design, and the best solution is determined using the highest AEP for a particular wind speed Weibull distribution as the optimization criteria with constraints of the top limit power output of the wind turbine. The outcomes demonstrate clearly that the proposed blade design optimization method offers a good opportunity for FPFS wind turbine blade design to achieve a better power performance and low manufacturing cost. This approach can be used for any practice of FPFS wind turbine blade design and refurbishment.     

Size optimization of a PV/wind hybrid energy conversion system with battery storage using response surface methodology

This paper aims to show the use of the response surface methodology (RSM) in size optimization of an autonomous PV/wind integrated hybrid energy system with battery storage. RSM is a collection of statistical and mathematical methods which relies on optimization of response surface with design parameters. In this study, the response surface, output performance measure, is the hybrid system cost, and the design parameters are the PV size, wind turbine rotor swept area and the battery capacity. The case study is realized in ARENA 10.0, a commercial simulation software, for satisfaction of electricity consumption of the global system for mobile communications (GSM) base station at Izmir Institute of Technology Campus Area, Urla, Turkey. As a result, the optimum PV area, wind turbine rotor swept area, and battery capacity are obtained to be 3.95 m², 29.4 m², 31.92 kWh, respectively. These results led to $37,033.9 hybrid energy system cost, including auxiliary energy cost. The optimum result obtained by RSM is confirmed using loss of load probability (LLP) and autonomy analysis.     

Optimization of Multibrid Permanent-Magnet Wind Generator Systems

This paper investigates the cost-effective ranges of gearbox ratios and power ratings of multibrid permanent-magnet (PM) wind generator systems by using a design optimization method. First, the analytical model of a multibrid wind turbine concept consisting of a single-stage gearbox and a three-phase radial-flux PM synchronous generator with a back-to-back power converter is presented. The design optimization is adopted with a genetic algorithm for minimizing generator system cost. To demonstrate the effectiveness of the developed electromagnetic design model, the optimization results of a 500-kW direct-drive PM generator and a 1.5-MW multibrid PM generator with various gear ratios are, respectively, compared with those from other methods. Then, the optimal design approach is further employed for a range from 750 kW up to 10 MW. The optimization results of PM generator systems including direct-drive and multibrid wind turbine configurations are obtained, and the suitable ranges of gear ratios for different power ratings are investigated. Finally, the detailed comparisons of the most cost-effective multibrid PM generator system and the optimized direct-drive PM generator system are also presented and discussed. The comparative results have shown that the multibrid wind turbine concept appears more cost-effective than the direct-drive concept.