【作者】 高剑；

【导师】 黄守道；

【作者基本信息】 湖南大学 ， 电机电器， 2013， 博士

【摘要】 风能是可再生能源中发展最快的清洁能源,也是最具有大规模开发和商业化发展前景的可再生能源,风力发电是最有效的风能利用方式。直驱永磁风力发电系统采用无刷无环的永磁同步发电机作为主发电机,取消了齿轮箱传动装置,具有结构简单、效率高、维护率和故障率低等特点,同时也具备了在恶劣环境下工作的能力,因此适合于海上大容量风力发电的发展方向,是符合风力发电技术发展趋势的一种机型。本文针对直驱永磁风力发机设计关键技术开展研究工作,主要包括以下几个方面：(1)介绍了当前典型的并网直驱永磁风力发电系统的基本结构,阐述了风轮机的基本原理与功率特性、直驱永磁风力发电机的数学模型、机侧变流器和网侧变流器的数学模型及其控制策略、直流母线环节的数学模型和直驱永磁风力发电机组功率控制方式以及最佳风能捕获原理,为后续各章节的研究工作奠定基础。(2)直驱永磁发电机通过一个背靠背全功率变流器与电网相连,电流和输出功率受到机侧变流器的控制,直驱永磁风力发电机的运行特性和设计方法具有其特殊性,因此准确分析变流器控制条件下直驱永磁风力发电机的运行特性,建立符合发电机运行特性的设计模型是直驱永磁风力发电机设计的关键问题。本文研究了直驱永磁风力发电机在变流器控制条件下的运行特性,推导了在机侧变流器isd=0矢量控制条件下发电机定子电压平衡方程、定子电压与直流母线电压之间的约束关系；研究了发电机定子电压、功率因数随电磁功率变化而变化的规律,阐明了直驱永磁风力发电机有功功率调节的基本原理；提炼了直驱永磁风力发电机在机侧变流器isd=0矢量控制条件下的重要运行特点,这将为下一章新的设计模型的提出奠定了理论基础。(3)分析了传统直接并网同步发电机设计分析方法在分析设计直驱永磁风力发电机时的缺陷和局限性。并将直驱永磁风力发电机矢量控制原理与经典电机设计“磁路计算”和“参数计算”有机结合起来,提出了基于变流器控制策略的直驱永磁风力发电机设计模型,该模型综合考虑了变流器电流矢量控制策略对发电机特性和性能的影响,能更准确的反应直驱永磁风力发电机的运行特性,并通过仿真和对比分析和试验研究的方式验证了本文提出的设计模型的准确性。(4)直驱永磁风力发电机转速低、体积庞大,其极数、极数／槽数匹配、永磁体尺寸等关键电磁参数具有很大的选择空间,因此准确分析各电机设计参数对电机性能和电机体积重量的影响是对电机进行优化设计的关键前提条件。本文研究了变流器控制条件下的直驱永磁风力发电机设计参数对性能和体积重量的影响,建立了直驱永磁风力发电机参数分析解析模型。利用该模型研究了发电机极数与发电机主要尺寸、电感参数和铁心损耗之间、极槽配合与发电机绕组系数、电动势波形之间、永磁体厚度和宽度与空载磁密、电动势、电感参数和铁心损耗之间、匝数和发电机性能之间的解析关系,得到了一系列有价值的结论,并通过直驱永磁风力发电机参数化电磁设计验证了上述结论。(5)齿槽转矩是永磁电机的固有特性,直接影响到直驱永磁风力发电系统的切入风速和能量捕获,因此如何降低齿槽转矩也是直驱永磁风力发电机设计的一个关键问题。本文分析了永磁电机齿槽转矩产生的机理,讨论了永磁电机设计参数与齿槽转矩之间的关系,介绍了选择合理极槽配合、改变电枢参数和改变永磁体参数来削弱永磁电机齿槽转矩的方法。通过研究不同极槽配合下单个永磁体和永磁电机总齿槽转矩之间的关系,提出了永磁电机基本齿槽单元的概念,整个电机永磁体可划分为若干个基本齿槽单元,每个基本齿槽单元产生的齿槽转矩在幅值和相位上完全相同。建立了基于齿槽单元的直驱永磁风力发电机永磁体移极齿槽转矩削弱方法,该方法运算简单,能有效的降低齿槽转矩,而且不会引入新的齿槽转矩谐波。(6)综合运用上述提出的直驱永磁风力发电机分析和设计方法,设计了一台2MW直驱永磁风力发电机,利用Ansoft和Matlab软件进行了电机本体的有限元仿真和系统的性能仿真。在湘电集团有限公司完成了电机的制造和测试,试验结果表明该电机各项性能指标均达到设计要求,试验数据与设计数据十分吻合,从而验证了本文所提出的直驱永磁风力发电机设计分析理论和方法的有效性与正确性。更多还原

【Abstract】 The wind power is not only the fastest development but also with the most scales using and commercialization prospects of the renewable energy. And the wind power generation is the most effective way to using this energy. Cancelling the gearbox and using the permanent magnetic synchronous motor as the main generator, the direct drive permanent magnet wind generation system is attractive because of its simple construct. So the simply construct, high efficiency and low faults become the characteristics of this system. Because of having the able of working on severe environment, this system is suitable for large capacity offshore wind power.In this paper, the direct drive permanent magnet generator is taken as the main researching object. The main research of this paper as follow:(1)The basic structure of the direct drive permanent magnet(DDPM) wind turbine is introduced.The principle and power characteristic of the wind turbine is elaborated.And then the main work is on the mathematical model of the DDPM wind generator and inverter,the control strategy,the model of the DC bus and the theory of the maximum wind energy capture.All of these is the foundations for later research.(2)Since the DDPM wind generator is connect into grid by a full power inverter,the current and the output power is controlled by the inverter of the motor.Thus the design method of the DDPM wind generator is different from the previous generator.In order to analysing the operator characteristic of the DDPM wind generator accurately,the key problem is setting up a new model which is based on the control strategy of the inverter. In this paper,the stator voltage equation and the relationship between the stator voltage and the DC bus with the vector control motor inverter id=0are derived by analysing the operator characteristic on the condition of controlling of the inverter.The laws of the stator voltage and the power factor varies with the variation of the electromagnetic power are studied.The important operator features of the DDPM wind generetor with the vector control id=0are obtained.All of these research work are crucial to establish the new model in next chapter.(3)The limitations of the design method of the tradition sychronous generator which is connected into the grid directly is analysed.In this paper,combining the theory of the vector control and the classical "Calculation of magnetic circuit" and "Parameter calculation",the new design model based on the inverter vector control is proposed.Considering the influence of the inverter control strategy,this design model can reflect the practical opertation more accuracy. The correctness of the proposed model is approved by the simulation and the comparative analysis.(4)As the DDPM wind generator process low speed and big size,the chosen of its slot/poles combination and size of the permanent magnet have a lot of space.How to analysing the influence of the design parameters to the performance and the weight of the motor is the critical condition for optimal design.Accordingly in this chapter,this problem is analysied on the condition of the control of inverter.The analytic model of the parameter analysis of the DDPM wind generator is established.Taking use of this analytic model the follow relationships(pole number and the size, the inductance parameter and the iron-core loss,the slot/pole combination and the winding coefficient,the waveform of the electromotance,the thichness and width of the permanent magnet and the no-load flux density,electromotance,inductance parameter and the the iron-core,number of conductors and the performance of the motor) are discussed.Some valuable conclusions are gained.And all conclusions are approved by parameters of electromagnetic design of the DDPM wind generator.(5)The cogging torque is inherent in permanent motor.And it effects the cut-in speed and the energy captruce directly. So how to decreasing cogging torque is also a key problem in the design system.Firstly,the mechanism of the generation of the is analyzed. The relationship between the design parameter and the cogging torque is considered.The method that reasonable slot/pole combination,changing the amature parameters and changing the permanent magnet parameters are reviewed.The novel concept elementary cogging unit is proposed by analysing the relationship betweent the single permanent magnet and the general cogging torque of the motro on the different slot/pole combination.The permanent magnet can be divided into many elementary cogging unit.And the cogging torque generated by the each unit process the same amplitude and phase.A new method based on the elementary cogging unit is presented to reduce the cogging torque.This method is not only simple but also effective.And more,no additional cogging torque harmonic is bringed.(6)A2MW DDPM wind generator is designed by using the proposed model and methods.The simulation of finite element and the performance of the system are carried out by Ansoft and Matlab software. Manufacturing and test of the generator are finished in Xiangtan Machine Group Co., Ltd. The test results show that the performance of the motor can meet the design requirement perfectly. And the test data fit well with the design data. All of those indicate that the design model and the analysis methods proposed in this paper are effective and correct.更多还原