定桨距风力发电机组叶片加装涡流发生器性能提升研究

加装涡流发生器有助于风力机叶片表面边界层气流分离的控制。针对我国高原地区定桨距风力发电机组长期处于欠发状态,发电性能难以达到满发的状况,对750 kW定桨距风力发电机组使用CFD数值模拟方法分析了其叶片表面的失速规律,提出了在叶片吸力面上安装涡流发生器来提升机组性能的技术方案。研究结果表明:涡流发生器技术实施运行1年后,机组年发电量的增长率达5.69%,展现了良好的经济性与实用性,对我国定桨距风力发电机组性能提升技术研究具有很好的指导意义。     

液压型风力发电机组低速性能仿真研究

为了实现风力发电机组在较低风速时对风能的利用,提出了一种大功率低速大扭矩径向柱塞泵以代替传统定量泵进行低速性能研究。介绍了液压型风力发电机组工作原理,建立了定桨距型风力机和定量泵-并联变量马达主传动系统数学模型,利用AMEsim软件进行了液压型风力发电机组仿真分析,结果表明在低风速下该机组效率可达85%,输出功率范围较大,接近传统机组。同时采用间接流量反馈加上直接转速闭环控制方式可实现变量马达恒转速输出发电。     

电控偏航型离网风力发电机组的设计研究

阐述了在离网型风力发电机组中运用电控偏航技术,从而使离网型风力发电机组实现超风速下桨叶偏航限速和桨叶顺桨停机保护,以便使离网型风力发电机组获得更高的发电效率,使离网型风力发电机组更加安全、可靠。     

基于神经网络PID的变速变桨距控制设计

在风力发电中,为了提高风力发电的能量转换效率对风力发电机进行变速变桨距控制,按照所需要的功率系数值确定所需要的变桨角度,以保证功率的稳定.本文研究利用神经网络PID控制器作为变速变桨距系统的控制器.在风速低于额定风速时,采用的是变速控制,此时风能效率高于采用失速控制风电机组的风能效率,具有优化的气动特性;在风速高于额定风速的情况下,根据风速的变化调整桨叶节距角,从而调节发电机的输出功率,使风力发电机组的输出功率保持稳定.最后,利用Simulink构建整个控制系统,对系统进行Matlab仿真.结果表明,使用神经网络PID控制的风力发电系统在风速从额定风速到切出风速时,相对失速控制风电机组,采用变桨距控制风电机组的功率恒定,发电品质较好.     

变速变桨距双馈风力发电技术研究

大型风力发电机组多具有变速变桨距功能,能够通过控制桨距角来调节机组的功率输出,使整个风力机的功率控制更为有效.通过对变速变桨距双馈风力发电机组的控制策略进行详细分析,给出了变速变桨距风力发电机组的MATLAB仿真波形,仿真结果验证了控制策略的正确性与可行性.     

风力发电机组变桨系统的设计

为了解决风力发电机组在复杂多变的风况下,能够基本保持其发电机稳定运转的问题,将PLC、变频器技术应用到风力发电机的变桨系统中。开展了变桨系统自动控制的分析,建立了PLC、变频器和变桨电机之间的关系,利用PLC及PLC的模拟量输入模块对风电场自然风风速以及风力发电机组3片桨叶的桨距角度进行了数据信息的采集,并自动进行了内部数据的处理;然后再通过对变频器的输出控制进而控制变桨电机的工作状态,使3片桨叶旋转到与自然风风速相对应的桨距角度。在发电机能自动保持稳定运转的基础上,对其性能进行了评价。分析和验证结果表明,该系统实现了对风力发电机组变桨系统的自动控制。     

基于载荷优化的风电机组变桨控制技术研究

风力发电是可再生能源中技术最成熟、最具规模开发条件和商业化发展前景的发电方式之一。现代风电机组的单机容量越来越大,叶轮直径也越来越大,风剪切、塔影效应等造成的载荷波动也在不断增大,由此导致的疲劳载荷问题日益明显,独立变桨控制技术正是在这种背景下提出来的。以国产兆瓦级风力发电机组为依托,研究大型风力发电机组独立变桨控制技术,来减小桨叶承受的不平衡载荷和保持输出功率的稳定。通过研究基于载荷优化的风电机组变桨控制技术,不仅能够提升风电机组的发电效率,还可以减小机组关键部件的载荷,保证机组安全稳定运行,实现客观上的发电量提升。     

风电机组液压独立变桨距系统的设计与分析

液压独立变桨距系统作为大型风力发电机组控制系统的关键部分,对机组的安全、稳定、高效运行具有十分重要的作用。该文简述了风力机液压独立变桨距系统的原理及特点,采用了带实时故障排除的液压冗余型电液伺服变桨距执行机构;计算分析了桨叶的驱动力矩及液压缸的负载力。     

浅析定桨距风力发电系统组成

主要对定桨距风力发电系统进行研究,介绍了定桨距风力机发电系统的组成及其运行启动等。得出了采用小电机使桨叶具有较高的气动效率,提高了发电机的运行效率。     

100kW海洋能发电装置变桨距机构的参数设计研究

变桨距机构作为风力机上十分常用的优化能效输出装置,在海洋能发电装置中也发挥着重要的作用,其在功率调节、转轮制动和主动控制失速输出比等方面表现出诸多优异性能。本文通过动量理论,分析了桨叶的最大能量捕获规律,并结合流体动力学和叶素理论,对桨叶进行了力学特性分析,得出了满足理论要求的变桨距机构的设计参数。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...