海上风电机组机型发展的技术路线对比

大型化是海上风电未来发展的重要趋势,海上风电机组的类型也从恒速恒频发电机组发展到变速恒频发电机组,双馈异步风电机组、永磁和电励磁同步风电机组、笼型异步风电机组4种技术路线均可采用变速恒频控制技术。从发电机类型和控制策略、传动系统和吊装维护两个方面,对不同类型海上风电机组的性能进行比较,由于采用不同的发电机技术、变速恒频控制方法和传动系统,实际应用中也是各有优缺点。从经济性来看,电励磁直驱同步风机系统的成本最高,成本较低的是双馈异步和永磁半直驱同步风机系统;永磁直驱同步发电机组的年发电量最多,其次是电励磁直驱同步风机系统,永磁半直驱同步风机系统介于电励磁直驱同步风机系统和双馈异步风机系统之间;永磁半直驱同步风机系统的度电成本最低。国外海上风电机组以永磁直驱和永磁半直驱同步发电机组两种技术路线为主,而永磁半直驱同步风机系统具有较好的性能和经济性,更适合目前我国海上风电行业的发展现状。     

风电场变速恒频风力发电机之间谐波扰动研究

变速恒频风力发电机在工作过程中会产生谐波,当双馈异步风力发电机风速达到切入风速时,并入电网的双馈异步风力发电机与其他直驱永磁风力发电机之间会因为功率传递产生谐波扰动,文章研究分析了此问题,并根据瞬时无功理论和其他风力发电有关理论在Matlab中进行建模和仿真,仿真结果表明亚同步发电状态双馈异步风力发电机会因为功率传递受到正常工作直驱风力发电机的谐波扰动,扰动会随着风力发电机数量的增多而加剧。     

1kW离网型风力发电机的研究与开发

结合内蒙古的风资源情况研制了lkW离网型风力发电机,在叶片的设计计算中应用了"根据发电机对蓄电池充电特性曲线,设计叶片的空气动力特性及外形"的新设计理念,使叶片在蓄电池的充电过程中与发电机得到很好的匹配.研制的直接驱动式稀土材料永磁外转子内定子发电机,改善了机组动态特性,各风速段运行平稳,大大提高了风力发电机的使用寿命.风场测试结果表明,所研制的1kW风力发电机准确地达到了预期考核指标,可作为内蒙古小型风力发电机的更新换代产品进行示范.     

永磁技术应用于风力发电机的挑战

世界上十大风机制造商,有超过一半的制造商正在进行永磁发电机技术的研究,或是早已向市场推出了永磁发电机产品.通常,最简单的将传统双馈异步发电机转换为永磁发电机的办法就是用同速的永磁发电机和全功率变流器替代现在高速齿轮箱后面的双馈异步发电机,仅需要对风机和机舱布置做很小的设计改动.永磁技术提供了各种不同的概念,从10 r/min到20 r/min的大转矩直驱发电机.同时也提供了各种结构方式,像外转子轴向磁通发电机,永磁励磁使电机同时具有高效、高转矩,因为励磁不需要向系统连续地输入能量.而且,也会产生较低的同步电感,可使电机具有大转矩.     

基于垂直轴风力机的盘式永磁电机的试验研究

随着永磁材料的发展,盘式永磁发电机的技术突破,基于盘式发电机的小型垂直轴风力发电机重新得到重视。设计出双外转子中间定子的盘式永磁发电机,安装在Φ型风力机下端,利用风洞实验室进行不同风速下的试验研究,试验得到无负载与蓄电池负载下的2组数据。数据表明,盘式发电机应用在Φ型垂直轴风力机中,启动性能不理想,但在风力机启动后功率可以很快达到额定功率,故在启动性能好组合式垂直轴风力发电机具有良好适用性。     

三种风力发电机组的建模与仿真

建立了包括异步感应式发电机、双馈感应式发电机和永磁同步发电机在内的3种不同的风电机组数学模型,针对不同的机组类型提出了相应的风力机模型和变频器控制策略.以建立的数学模型为基础确立了接入无穷大系统的风电场模型.模拟风力机风速变化情况,对各个风机模型在风速扰动下的响应特性进行了仿真分析研究,并将仿真波形进行了简单的比较.结果验证了所建模型的正确性,并且表明变速恒频发电机组与异步发电机比较而言具有更好的动态特性.     

笼型异步发电机和SVG用于独立运行风电系统

提出了笼型异步发电机和静态无功发生器(SVG)构成独立运行的风力发电系统,由SVG代替电容器提供发电机励磁,避免了依靠并联电容器提供无功功率的缺点.通过实验装置验证,当输入转速发生变化时,通过SVG的调节.异步发电机输出电压基本保持在一个比较理想的范围.     

离网型风力发电测试及实验系统一体化研究

利用LabVIEW软件及相关配套硬件设备,开发了一套实用的基于虚拟仪器技术的离网型风力发电性能测试系统。为简化离网型风力发电模拟系统结构、降低成本,设计了包含变频器、异步电动机、永磁同步发电机、二极管整流桥堆、升压斩波器、铅酸蓄电池、全桥逆变器和负载的小型风力发电实验系统。针对系统能量转换的核心——蓄电池,采用HC16F877单片机和Boost斩波电路实现其智能充放电控制;对决定系统性能的逆变器进行了理论分析和基于MATLAB的计算机仿真。所提方案正确可行,对离网型风力发电系统的研究开发具有工程指导意义。     

1kW离网型风力发电机的设计

结合内蒙古的风能分布情况研制了1 kW离网型风力发电机,在叶片的设计计算中应用了"以发电机对蓄电池充电特性曲线,设计叶片的空气动力特性及外形"的新设计理念,使叶片在蓄电池的充电过程中与发电机得到很好的匹配.风场测试结果表明,所研制的1 kW风力发电机准确地达到了预期考核指标,该机可作为内蒙古小型风力发电机的更新换代产品进行示范.     

小型风力发电机电磁设计特点

文章分析了小型风电机组用的永磁同步发电机的电磁设计特点,并与其他普通永磁电机区别,详细介绍了永磁同步发电机各个电磁参数的特点以及对发电机性能的影响。重点介绍永磁同步发电机定子、转子设计的特点,对不同的极数与槽数的配合进行对比分析,总结降低齿槽转矩的规律。     

General study of the control principles and dynamic fault behaviour of variable-speed wind turbine and wind farm generic models

The interest towards generic models or sometimes also called standard models of wind turbine generators (WTGs) is significantly increasing. Mainly due to their improved power quality, better controllability and higher power extraction capability, variable-speed wind turbines driving a synchronous or an induction machine are capturing the global market. Throughout this paper, dynamic modelling and performance analysis of the generic models of the variable-speed WTGs, namely the doubly-fed induction generator and the fully-rated converter based WTGs, are achieved using integration between Matlab/Simulink and PSCAD/EMTDC simulation platforms. Later on, the performance of type-4 wind turbine driving a permanent magnet synchronous machine is analysed during fault and then compared with the case when driving a wound rotor induction machine. The differences in control principles and dynamic fault behaviour are highlighted. Afterwards, investigations on wind farm level are accomplished. A case study during which the developed generic models and the generic model of the variable-speed machine are compared is conducted. Different arrangements for the construction of the generic wind farm are considered.     

Aggregated models of permanent magnet synchronous generators wind farms

This paper evaluates the responses of three aggregated models of a wind farm consisting of variable speed permanent magnet synchronous generator wind turbines when wind fluctuations or grid disturbances occur. These responses are compared with those of the detailed wind farm model, in order to verify the effectiveness of the studied aggregation methods for this type of wind farms. The equivalent wind farm models have been developed by adapting different aggregation criteria that already exist in technical literature and had been applied to other technologies. In this work, these methods have been modified to suit them to the permanent magnet synchronous generator technology. The results show that the three aggregated models provide very similar results to the detailed model, both in the evolution of active power when fluctuations in wind speed occur, and in the active power and DC-link voltage during the two simulated voltage dips. Notably, the aggregated model with an approximate mechanical torque offers excellent results.     

Peak current mode control of three-phase boost rectifiers in discontinuous conduction mode for small wind power generators

This paper presents a peak current mode control scheme of a boost rectifier with low distortion of the input current for wind power systems based on permanent magnet synchronous generators with variable speed operation. The three-phase boost rectifier is operated in discontinuous conduction mode (DCM), and power factor correction techniques are applied. It is shown that the DCM operation significantly reduces the total harmonic distortion of the currents in the permanent magnet synchronous generator, increasing the power factor of the system, so that the vibrations and mechanical stress of the generator are minimized. The characteristics of the DCM boost rectifier are studied considering: (1) the series resistance of the inductors; (2) the modeling and adjustment of peak current mode control yielding a stable loop; (3) the design of an input filter that reduces the switching noise in the currents of the generator.     

Loss evaluation and design optimisation for direct driven permanent magnet synchronous generators for wind power

When designing a generator for a wind turbine it is important to adapt the generator to the source, i.e. the wind conditions at the specific site. Furthermore, the variable speed operation of the generator needs to be considered. In this paper, electromagnetic losses in direct driven permanent magnet synchronous generators are evaluated through simulations. Six different generators are compared to each other. The simulations are performed by using an electromagnetic model, solved in a finite element environment and a control model developed in MATLAB. It is shown that when designing a generator it is important to consider the statistical wind distribution, control system, and aerodynamic efficiency in order to evaluate the performance properly. In this paper, generators with high overload capability are studied since they are of interest for this specific application. It is shown that a generator optimised for a minimum of losses will have a high overload capability.     

Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid

Wind energy is a prominent area of application of variable-speed generators operating on the constant grid frequency. This paper describes the operation and control of one of these variable-speed wind generators: the direct driven permanent magnet synchronous generator (PMSG). This generator is connected to the power network by means of a fully controlled frequency converter, which consists of a pulsewidth-modulation (PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator is controlled to obtain maximum power from the incident wind with maximum efficiency under different load conditions. Vector control of the grid-side inverter allows power factor regulation of the windmill. This paper shows the dynamic performance of the complete system. Different experimental tests in a 3-kW prototype have been carried out to verify the benefits of the proposed system.     

Three-phase self-excited induction generators: an overview

Induction generators are increasingly being used in nonconventional energy systems such as wind, micro/mini hydro, etc. The advantages of using an induction generator instead of a synchronous generator are well known. Some of them are reduced unit cost and size, ruggedness, brushless (in squirrel cage construction), absence of separate dc source, ease of maintenance, self-protection against severe overloads and short circuits, etc. In isolated systems, squirrel cage induction generators with capacitor excitation, known as self-excited induction generators (SEIGs), are very popular. This paper presents an exhaustive survey of the literature over the past 25 years discussing the process of self-excitation and voltage buildup, modeling, steady-state, and transient analysis, reactive power control methods, and parallel operation of SEIG.     

A review of power converter topologies for wind generators

Wind energy conversion systems have become a focal point in the research of renewable energy sources. This is in no small part due to the rapid advances in the size of wind generators as well as the development of power electronics and their applicability in wind energy extraction. This paper provides a comprehensive review of past and present converter topologies applicable to permanent magnet generators, induction generators, synchronous generators and doubly fed induction generators. The many different generator–converter combinations are compared on the basis of topology, cost, efficiency, power consumption and control complexity. The features of each generator–converter configuration are considered in the context of wind turbine systems.     

不同槽型对海浪发电用永磁直线同步发电机的影响研究

针对海浪发电机采用永磁直线同步发电系统会引起电机严重振动进而发生永磁体断裂的问题,基于直线电机与永磁电机理论,分析了两种槽型对海浪发电用永磁直线同步发电机的电磁力的影响,通过仿真计算确定了采用开槽结构进一步优化电机结构,使海浪发电为用永磁直线同步发电机齿槽力最小。     

Investigating the overload capacity of a direct‐driven synchronous permanent magnet wind turbine generator designed using high‐voltage cable technology

Utilization of wind energy to maximum permissible limits for generating electrical power has become necessary to meet the global energy demands. Under such circumstances the present day conventional wind turbine generators pose a limitation regarding the overload capability, specifically significant when they need to operate in high‐energy wind conditions. It is proposed that by employing a completely different generator winding concept, based on high‐voltage cable technology, to a specific generator, it is possible to increase the generator overload capabilities and thereby making it operationally efficient in high wind speed situations. Therefore, the possibility of extracting more energy is predicted to increase. Simulations, based on finite‐element methods combined with external circuit models for the generator, have been performed. The results demonstrate that under given thermal and electrical restrictions, a direct‐driven permanent magnet synchronous wind turbine generator, based on high‐voltage cable windings, is capable of being overloaded more than twice the rated power, thus making it very suitable for strong wind situations. Copyright © 2007 John Wiley & Sons, Ltd.     

基于Matlab/Simulink的永磁直驱风力发电机组建模和仿真研究

以永磁直驱风力发电机组为研究对象,建立了包括风力机、传动部分、永磁直驱发电机、矢量控制策略、最大风能捕获策略的整体数学模型;应用Matlab/Simulink工具,以建立的数学模型为基础搭建了永磁直驱风力发电机组仿真模型,并以两次阶跃风速为例对所建模型并网后运行特性进行了仿真研究。实现了永磁直驱风力发电机组的最大风能捕获和功率解耦控制,仿真结果表明,永磁直驱风力发电机组具有良好的运行特性,同时验证了所建模型的正确性和有效性。