不同对称翼型H型风力机气动性能数值模拟研究

风轮是风力发电机利用风能的核心部件,而翼型作为风轮的关键零件,其结构参数的选择的不同会对风力机性能造成极大的影响。本文选取3种常用的H型垂直轴风力机NACA系列对称翼型的绕流流动,建立其湍流流场的模型,采用移动网格技术对其进行数值分析与计算,得出风轮的力矩系数、功率及风能利用率的变化规律,在此基础上,详细分析了不同的对称翼型对垂直轴风力机风轮气动性能的影响。根据其气动性能曲线,拟合出给定工况下,风能利用率随尖速比的变化公式,更好的实现定量分析。     

Design and Parametric Investigation of Horizontal Axis Wind Turbine

This research focuses on design and calculations for the horizontal axis wind turbine to fulfill energy demands at small scales in Pakistan. This is the design to produce about 5 kilowatts of electricity to share the load of average home appliances. Area chosen for this research is Pasni, Balochistan in Pakistan to build the wind turbine for electricity. Design values are approximated by appropriate formulas of wind energy design. In current research, turbine blade profile is designed by blade element momentum (BEM) theory. Warlock wind turbine calculator is used to verify the design parameters like wind speed, tip speed ratio (TSR) and efficiency factor. Effects of wind speed, wind power, TSR, pitch angle, blade tip angle, number of blades, blade design and tower height on power coefficient are analyzed in this research. Maximum power coefficient is achieved at a designed velocity of 6m/s. Design analysis is also performed on simulation software ANSYS Fluent. It is observed that designed velocity parameter of this research is very suitable for the turbine blade, so blade designing is perfect according to wind speed range.     

桥塔上风传感器安装位置对测量结果的影响

为探讨桥塔上风传感器安装位置对测量结果的影响,以计算流体力学大型商用软件Fluent为平台,采用有限体积法对计算域进行离散,基于k-湍流模型研究了桥塔附近的风场特性.分析了不同来流风速、不同来流风向下桥塔附近风观测点的风速、风向变化规律,给出了相应的风速修正系数和风向角修正值.研究结果表明:桥塔对测量结果的影响较大,桥塔上风传感器的安装位置应经过优化确定.风传感器位于迎风侧时,风速比值在0.45~1.30之间波动;位于背风侧时,风速比值在0.05~1.25之间波动.风传感器较优的安装位置为离塔1.0倍特征尺寸以上,且与来流方向的夹角在(45.0~56.5)范围内.      

变速恒频双馈风力发电系统励磁控制策略仿真研究

能源问题正受到全世界的广泛关注,风能的有效开发利用变得愈加重要,因此先进的风力发电技术的研究成为热点。变速恒频（VSCF）双馈风力发电系统是目前风力发电系统的主流,在该系统中,励磁控制技术的研究是关键。对VSCF双馈风力发电机组的基本功率控制策略进行了研究。在额定风速以下运行时,转子励磁控制系统通过双馈发电机转速的控制,跟踪最佳风能利用系数曲线以获得最大功率,给出了最佳风能捕获控制系统励磁控制算法。在高于额定风速运行时,通过变桨距和励磁控制技术相结合实现恒功率控制,建立了简洁、直观的变桨距控制与励磁控制的控制算法,并对控制算法进行了仿真。     

船舶余热海水淡化系统的探讨

船舶海水淡化装置是海洋船舶的重要设备,其节能性的好坏直接关系到船舶的整体节能.分析了船舶余热的构成和当前船舶海水淡化系统的优缺点,提出了船舶余热梯级利用海水淡化系统设计方案和研究方法,为开发新一代高效节能的船舶海水淡化装置奠定了基础.     

Dynamic response analysis of a multi-column tension-leg-type floating wind turbine under combined wind and wave loading

Floating wind turbines (FWTs) are subjected to combined aerodynamic and hydrodynamic loads varying both in time and amplitude. In this study, a multi-column tension-leg-type FWT (i.e., WindStar TLP system) is investigated for its global performance under normal operating conditions and when parked. The selected variables are analysed using a fully coupled aero-hydro-servo-elastic time domain simulation tool FAST. Three different loading scenarios (wind only, wave only and both combined) are examined to identify the dominant load influencing each response. The key response variables are obtained and compared with those for an NREL 5MW baseline wind turbine installed on land. The results should aid the detailed design of the WindStar TLP system.     

双馈风力发电系统MPPT控制技术的研究

介绍了变速恒频风力发电的基本原理,并采用定子磁链定向的矢量控制方法得到了双馈发电机的矢量控制系统模型.本文利用Matlab软件建立了该系统的仿真模型,仿真结果验证了这种矢量控制策略既能保证定子输出频率的恒定,又能达到有功功率和无功功率的独立解耦控制,同时还能较好地跟踪风力机的最大功率输出.     

风力发电塔系统整体建模与模态分析研究

为了判断风力发电塔系统是否能避开共振,需对其进行模态分析。提出了考虑“桨叶-轮毂-机舱-塔筒”耦合的整体建模的方法,可用于风力发电塔系统模态的计算。分别进行了停机阶段、运行阶段和切出阶段的模态分析,对比其频率和固有振型。对比结果表明：三个阶段的频率基本相同,只须验算停机状态下的频率满足规范即可;塔筒的振动形式主要为侧向弯曲振动、前后弯曲振动和扭转振动;桨叶在前十阶的振动形式主要为挥舞振动和摆振,且三桨叶振动存在一定的规律;相对于停机阶段,运行阶段时振型基本相同,切出阶段时振型有较大差异。     

基于神经网络的传感器故障诊断仿真

针对现代工业大型复杂系统的不确定性使得对其进行建模比较困难的特点，提出了一种用神经网络进行传感器故障诊断的方法．以凝汽式汽轮机调速系统中的转速传感器为例进行了传感器故障诊断研究，给出了仿真实现结果，并加以分析．仿真结果表明，所提出的利用神经网络进行传感器的故障诊断的方法具有可行性．     

Wind turbine gearbox reliability analysis based on the system level stress-strength model

In order to estimate the reliability of wind turbine gearbox based on the system level, a generalized stress-strength model is introduced. Considering that the system works properly under a variety of random stresses which affect every component, the total stress on the system is given by a known linear combination of the stresses of all components. Then the strength of the system can be viewed as a linear combination of the strengths of relative components. In this model, stress and strength are independent of each other. Reliability of the system is the probability that strength exceeds stress. Finally, the reliability of wind turbine gearbox is estimated by the multivariable reliability calculation method. The corresponding result is compared with the results of reliability in the extreme cases(completely dependent and completely independent) by the traditional evaluation method.     

Wind Generator Stabilization with Doubly-Fed Asynchronous Machine

This paper investigates the function of doubly-fed asynchronous machine(DASM)with emphasis placed on its ability to the stabilization of the power system including wind generators.P(active power)and Q(reactive power)compensation from DASM can be regulated independently through secondary-excitation controlling.Simulation results by power system computer aided design(PSCAD)show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures.Comparison studies have also been performed between wind turbine pitch control and proposed method.     

基于EMD与SVM的风电功率短期预测

由于风电存在着不确定性,风电功率预测对于接入大量风电的电力系统意义重大.为了提高风电功率的预测精度,本文建立了基于经验模式分解法（EMD）与支持向量机（SVM）的复合预测模型.考虑到风力机组的输出有很强的非线性,该模型首先将训练数据按风速大小分成高、中、低3组,然后对各组的风电功率样本序列进行经验模式分解,并建立各个频带分量的支持向量机预测模型,各模型的预测结果等权求和即得到最终的功率预测值.使用风电场现场采集数据的预测结果,验证了该方法的可行性和有效性.     

Simple Approach on Intermixing Solar and Wind Energy and Minimizing Their Intermittent Effect

Renewable energy resources especially wind and solar energy are emerging as the modern power sources to electrify remote areas. The main reason behind their emergence is due to their environment-friendly behavior,unlimited availability and short period for replenishment over nonrenewable energy resources. Renewable energy resources are much better than nonrenewable energy resources, but the intermittency in renewable energy resources degrades the system performance. In order to overcome the intermittency, multiple hybrid system techniques were proposed in literature that can achieve suitable results but have disadvantages of complicated control structures and high implementation cost. Considering aforementioned shortcomings, a simple balancing approach is proposed to intermix solar and wind energy together so as to utilize the available energy from both sources at a given time.It is very common that solar farms are the dominating source of energy in daytime and summer, while wind farms are the dominating source of energy at night and in winter. The proposed approach delivers maximum possible power to the load by combining dominating and non-dominating resources all the time, hence mitigating the intermittency of individual resources. Compared with other approaches, the proposed approach offers key benefits with redundancy, simple design and low cost, which can be analyzed from simulation results.     

Reliability Copula Model for Wind Turbine Gearbox Based on Failure Correlation

On the basis of each gear’s failure correlation, the reliability Copula model of a wind turbine gearbox is established and a 1.5 MW wind turbine gearbox is taken as the research object. Firstly, based on the dynamic reliability model of mechanical parts, each gear’s life distribution function of a wind turbine gearbox is obtained.The life distribution function can be used as the marginal distributions of the system’s joint distribution. Secondly,Copula function is introduced to describe the failure correlation between parts, and the appropriate Copula function is selected according to the shape characters of Copula probability density function. Finally, the wind turbine gearbox system is divided into three parts according to the failure correlation of each gear. The Sklar theorem and the thought of step by step analysis are used to obtain the reliability Copula model for a wind turbine gearbox based on failure correlation.     

Design of Wind Turbine Blade for Solar Chimney Power Plant

Aiming at the global efficiency of solar chimney power plant (SCPP), we design a wind turbine generation device to elevate its electricity generating efficiency. Based on wind power utilization theory, a new method is proposed to design a type of wind turbine blade for SCPP. The lift and resistance coefficients on different Reynolds numbers of NACA4418 airfoil, which is suitable for experimental solar electricity generation system, are determined by Profili-V2.0 airfoil design software, a program written in Matlab to calculate chord length of the airfoil. The optimization is conducted by class-shape-transformation (CST) parameterization method and Xfoil software. An airfoil design program is designed on the basis of blade element theory and attack angle with the highest lift coefficient to iteratively determine the inflow angle and setting angle. Prandtl’s tip-loss factor is applied to correct the setting angle, after the airfoil data are input into AutoCAD to build an airfoil model which is then imported into Solidworks to draw blades. A new way is put forward to design wind turbine blades in SCPP.     

轨道车辆制动系统智能控制与维护技术研究进展

围绕轨道车辆普遍采用的微机控制直通电空制动系统，介绍了制动系统的结构组成、工作原理和控制原理，分析了制动系统的技术特性，总结和探讨了制动系统智能化的技术发展趋势，从制动系统的智能控制与智能维护两方面，对制动系统的研究现状、存在的问题进行了综述。研究结果表明:轨道车辆制动系统是一个复杂的“机电气(液)”耦合的动态时变非线性控制系统，其服役过程与故障行为具有不确定性、模糊性和小样本性的特征；在制动系统控制技术方面，相较于理论制动力控制，速度黏着控制和减速度控制2种制动控制模式在处理外界干扰影响时控制效果均有所提升；针对制动系统控制中存在的外界干扰、性能衰退或潜隐故障等不确定因素，基于参数辨识和闭环反馈的自主智能控制是制动系统智能控制技术的发展趋势，核心目标是实现外界干扰的自适应、性能衰退的自保持以及潜隐故障的自调节；在制动系统维护技术方面，制动系统运用维护主要涉及状态监测、故障诊断，对于故障预测与状态评估的研究还很少；充分利用制动系统服役状态信息，加强多源因素耦合作用下的制动系统服役行为与演化规律研究是制动系统智能维护技术的发展趋势，应进一步开展制动系统的服役性能一致性分析评价、传感器布局优化和剩余使用寿命预测方法研究。      

铁山湾海域风浪数值模拟研究

随着北部湾的快速发展,铁山湾海域将规划建设数百个泊位．基于SWAN建立了该海域风浪数学模型,选取铁山湾海域影响较大的5个风向,研究不同风要素组合作用下的波浪特征,计算得到了建港方案实施前、后的波浪场分布．研究结果表明：S-SSW风向对该海域的风浪影响最大,SE-SSE和SW-WSW风向次之,E-ESE和W-WNW风向的影响相对较小．建港方案实施后,工程区的波浪强度整体小于工程前的;人工岛起到了很好的掩护作用．     

连霍高速公路哈密—吐鲁番区间防风技术研究

在沿线风害成因、分布特征、基本风速对比分析研究基础上,确定连霍高速百里风区防风区段和防风标准,提出高速公路强横风路段采用柔性防风阻沙栅的防风措施,对于今后我国高速公路风害防控技术研究和高速公路安全、高效行车具有一定的指导意义和科学借鉴作用。     

大型数据库管理系统中主机性能测评及工作模式设计

本文针对大型数据库管理系统中缺乏平台质量评测手段的问题,建立了TPC-C基准评测体系。首先介绍了主机性能评测的通用原则,然后分析了TPC-C基准评测体系的模型结构和原理,最后提出了根据业务特点推算主机处理能力的TPC-C基准评测方法,同时设计了主机系统的工作模式。     

Data Fusion Algorithm for Multi-Sensor Dynamic System Based on Interacting Multiple Model

This paper presents a data fusion algorithm for dynamic system with multi-sensor and uncertain system models. The algorithm is mainly based on Kalman filter and interacting multiple model(IMM). It processes crosscorrelated sensor noises by using augmented fusion before model interacting. And eigenvalue decomposition is utilized to reduce calculation complexity and implement parallel computing. In simulation part, the feasibility of the algorithm was tested and verified, and the relationship between sensor number and the estimation precision was studied. Results show that simply increasing the number of sensor cannot always improve the performance of the estimation. Type and number of sensors should be optimized in practical applications.