Blade-pitch-angle-controllable windmill simulator

The paper describes the development of a windmill simulator, to simulate accurately the movement of a windmill. The simulator has a model to facilitate the change of windmill parameters, such as power coefficient or moment of inertia, by overcoming the weak points in the research and development environment for wind utilization, especially with the purpose of improving methods of windmill speed control or output. Also, to determine further the dynamic characteristics of the windmill speed with great accuracy, the simulator has a motor model to compensate for the slow response of the DC motor itself. The simulator is mainly composed of a separately-excited DC motor to directly simulate the movement of the windmill, a high-output DC amplifier to drive the motor, and a personal computer for control. It is ascertained that the developed simulator can fully reproduce the stationary and dynamic characteristics of a windmill from the experimental results. Also, a method is described to control the blade pitch angle to keep a windmill rotational speed constant. The results of the numerical simulation agree with the characteristics of the windmill simulator, and the effectiveness of the blade pitch angle control of the simulator is also affirmed.     

高次多项式动力凸轮优化设计及MATLAB算法实现

建立六项式动力凸轮型线的优化设计数学模型，以此为基础在MATLAB平台上开发较通用的内燃机配气凸轮优化设计程序，包括输入、输出界面和优化算法的实现，为配气凸轮设计提供了一种非常有效的手段。     

基于NX的凸轮曲线设计及两种凸轮机构参数转换

凸轮机构是一种由凸轮、从动件和机架组成的传动机构,常用于机械设备中,可以获得较复杂的运动规律。在发动机的结构中,凸轮机构是配气系统的重要组成部分,凸轮轮廓曲面的形状及其加工精度直接影响到进、排气的流量变化。本文主要讲述应用NX进行凸轮轮廓曲线的设计及通过运动仿真分析不同凸轮机构参数转换的方法,为凸轮轴车铣复合加工中心及数控凸轮轴磨床凸轮外形加工提供重要技术依据。     

Study on modelling and its parameter estimation of a multibladed windmill

The paper presents a modelling technique and a method for determination of the windmill torque loss coefficients of a multibladed windmill. First, a new model is presented of a multibladed windmill, and the windmill torque loss coefficients are defined. Next, a measuring method based on a recursive estimation technique is developed for determination of the values of these coefficients. The torque loss coefficients are estimated satisfactorily from the simulated data and experimental data for changes in wind speed. The validity of the windmill model and the proposed estimating technique are demonstrated.     

圆族包络法加工摇摆式凸轮磨靠模及靠模廓线特征

介绍了圆族包络法加工摇摆式凸轮磨靠模的原理,论证了靠模廓线的＂不对称＂和＂最大升程不相等＂的形数特征,并对由凸轮磨砂轮半径变化引起的工件升程误差给出了实例数据。     

Validation of various windmill brake state models used by blade element momentum calculation

The concept of windmill brake state model is considered in this paper. Blade Element Momentum (BEM) calculation often calculates the value of thrust coefficient in windmill brake state. Unfortunately, thrust coefficient predicted by momentum theory deviated dramatically from the experimental data when the value of axial induction factor is greater than 0.5. To solve this problem and to increase the accuracy of the prediction, windmill break state model including tip loss effect must be applied to equations of thrust coefficient. The problem of interest is that which windmill break state model is suitable for the wind turbine model being simulated. The purpose of this paper is to compare the rotor power predicted by six different windmill brake state models. The aerodynamic code based on BEM theory has been implemented in Matlab and validated with the simulated result of AWT-27 wind turbine model reported by National Renewable Energy Laboratory (NREL). Six windmill brake state models to be compared are Glauert’s characteristic equation, classical brake state model, advanced brake state model, Wilson and Walker model, modified advanced brake state model, and Shen’s correction. The predicted power curves obtained from each windmill brake state model are compared to the measured power curve of AWT-27/P4. It has been shown that Shen’s correction gives the highest correlation to the measured data with r-square of 0.970 and the predicted annual energy production (AEP) is different from measured data by only 6.3%.     

A method of measuring windmill torque loss coefficients

The aim of this work is to investigate a method of measuring windmill torque loss coefficients of a windmill power system. We discussed the mathematical windmill model and defined the windmill torque loss coefficients. An estimating technique based on Kalman filtering was developed for decision of the value of these coefficients. We manifested the valdity of this method by the estimated results from both the simulated data and wind-tunnel experimental data.     

Doubly fed induction generator model for transient stability analysis

This paper proposes a model of the doubly fed induction generator (DFIG) suitable for transient stability studies. The main assumption adopted in the model is that the current control loops, which are much faster than the electromechanic transients under study, do not have a significant influence on the transient stability of the power system and may be considered instantaneous. The proposed DFIG model is a set of algebraic equations which are solved using an iterative procedure. A method is also proposed to calculate the DFIG initial conditions. A detailed variable-speed windmill model has been developed using the proposed DFIG model. This windmill model has been integrated in a transient stability simulation program in order to demonstrate its feasibility. Several simulations have been performed using a base case which includes a small grid, a wind farm represented by a single windmill, and different operation points. The evolution of several electric variables during the simulations is shown and discussed.     

直动平底挺柱凸轮的优化设计

针对直动平底式凸轮建立了缓冲段等加速-等速与工作段七项高次方的组合式从动件运动规律数学方程式;并应用MATLAB软件进行优化设计,获得较大的丰满系数和较好的动力学性能;利用坐标变换的方法得到的凸轮轮廓线可为凸轮机构的动力学仿真和数控加工编程提供依据.     

基于复合形法的车用发动机配气机构凸轮型线设计

介绍了用复合形法设计最优的高次多项动力凸轮型线的方法和步骤,并以某机型的配气机构为例,并结合Matlab软件进行编程计算,结果验证了此方法的可行性,并同时指出了此方法的不足之处。     

6200Z系列柴油机配气凸轮型线的改进设计

本文介绍潍坊柴油机厂生产的６２００Ｚ系列柴油机的配气凸轮型线改进设计,并通过对比试验证明,改进后的配气凸轮型线对于提高６２００Ｚ系列柴油机可靠性和经济性具有明显的效果．     

BQ型柱塞油泵内二甲醚柴油混合燃料的气阻仿真

为研究二甲醚/柴油混合燃料在燃料供给系统内气阻的产生机理和影响因素,依据BQ型柱塞油泵建模,运用Fluent软件分析油泵凸轮不同转速下,以及进油阶段不同泵内初始压力和不同进油压力条件下油泵内的流体分布情况。分析表明:混合燃料中DME含量越高,气阻现象越明显;改变凸轮型线,增加柱塞在密闭泵腔阶段下行的速度,有利于减少泵内液态DME的气化,降低进油开始时泵内的初始压力,进油时泵内初始压力越低,进油压力越高,越有利于泵内气态DME的重新液化,避免进油受阻现象的发生。     

增压柴油机两种新型配气凸轮

增压柴油机要求配气凸轮必须具有较大的时间截面和良好的动力学性能,一般常用的配气凸轮很难同时满足上述两方面的要求。本文针对增压柴油机配气凸轮的特点,提出了两种适用于增压柴油机的新型凸轮,阐明了基本原理,给出了计算公式,拟定了计算方法,最后以实例表明了这两种新型凸轮的实际效果。     

Sensor-less maximum power point tracking control for wind generation system with squirrel cage induction generator

This paper proposes a technique that determines the optimal windmill operation speed and the optimal rotor flux. Moreover, the position and speed sensor-less wind generation system using the electromotive voltage observer to estimate rotor position and full-order observer to estimate rotor speed and the windmill output torque are proposed. The position and speed sensor-less maximum power point of wind power generation system is controlled by using the above estimated values, optimized windmill operation speed for maximum output power and optimized rotor flux for minimum generator losses. The effectiveness of the position and speed sensor-less maximum power point tracking control for wind power generation system with squirrel cage induction generator is verified by simulations. The simulation results confirm that the proposed method can estimate the operation speed efficiently.     

Computer-aided design and engineering: A study of windmills in la Mancha (Spain)

This article presents a detailed study, of the Manchegan windmill. This type of windmill is a central symbol in the story of Don Quijote de la Mancha, by Cervantes, which this year celebrates its 4th centenary, and to which this article pays homage. There exist no publications dealing with the technical aspects of these windmills. Studies have been carried out on windmills in the south of Spain, but no comparison has been made between the two types of windmill. This paper studies the technological conditions of the original Manchegan windmills. We carry out a wind evaluation of the region, calculate the power and momentum of the windmills and discuss the results obtained with a comparison with the type of Southern Spanish windmill.     

Output power leveling of wind turbine Generator for all operating regions by pitch angle control

Wind energy is not constant and windmill output is proportional to the cube of wind speed, which causes the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce fluctuation, different methods are available to control the pitch angle of blades of windmill. In a previous work, we proposed the pitch angle control using minimum variance control, and output power leveling was achieved. However, it is a controlled output power for only rated wind speed region. This paper presents a control strategy based on average wind speed and standard deviation of wind speed and pitch angle control using a generalized predictive control in all operating regions for a WTG. The simulation results by using actual detailed model for wind power system show the effectiveness of the proposed method.     

高压喷射技术在P7泵上应用

本文通过油泵(P７泵）凸轮型线、阻尼出油阀的试验及优化设计以达到高的供油率,避免了异常喷射现象。改进后的Ｐ７泵与柴油机配套实现了高压喷射并达到了欧Ⅰ排放标准。     

Optimum windmill-site matching

A methodology for the selection of the optimum windmill for a specific site is developed. The selection is based on finding the capacity factors of the available windmills. This is done by using long-term wind speed data recorded at different hours of the day for many years. These data are then used to generate mean wind speeds for a typical day in a month. Probability density functions for the mean wind speeds for the different hours of the day are generated with the manufacturer's specifications on the windmills used to calculate the capacity factors for the windmills. The windmill with the highest average capacity factor for the specific site is the optimum one and should be recommended     

THEORETICAL PERFORMANCE OF WIND WHEEL TURBINES

A wind wheel turbine designed for low wind speed applications has been analytically investigated. The turbine is simple constructed from a bladed-assembly rotor directly exposed to the free wind on the upper half and exposd to the wind through a multiple ducting system on the lower half.

A theoretical analysis using an engineering model based on the impulse momentum theory is described for a range of blade numbers. The computed results of the torque and power coefficients for two-, three-. and four-blade-wheels are presented. The optimum number of blades was found to be three, using the maximum power coefficient as the performance criterion.

The computed values of the power coefficients are found to be higher than those associated with other wind machines for tip speed ratios up to a value of unity. The results also show that the 3-blade-wheel, with accelerating flow through the ducting system, has increased the power coefficient by 3.5 times as much as the ideal propeller type windmill. Torque coefficients which may have potential use in some domestic applications are also described. A starting torque coefficient as high as 6.0, for example, is computed for a 2-blade-wheel.     

椭圆—幂函数组合凸轮动力学优化设计

本文以椭圆幂函数凸轮型线建立动力学优化设计的数学模型。在设计中将整个配气机构简化成单质点振动模型,用龙格—库塔法求解数值。为了节省机时,选用一种新的优化方法——浮动正交网格法进行优化处理。这种方法也可用于其它凸轮型线的设计。