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风力发电系统中的电力电子变流技术
摘 要
风力发电变流系统是将风力发电机经励磁调节后输出的电压恒定、频率变化的电能转换为恒压、恒频的交流电能的装置，是风力发电系统中的一个重要的组成部分。它能实现对发电机输出的电压、电流、有功功率和无功功率等参数的快速动态调节，提高系统的功率因数，减少对电网的谐波污染，是当前风力发电技术的研究热点之一。本论文在对风力发电机组的结构、工作原理、关键技术分析的基础上，对850千瓦风力发电机组的变流器及其控制系统进行了研究。
论文首先分析了风力发电变流技术研究的背景和意义，介绍了风力发电系统的组成结构及其各部分的工作原理。同时，介绍了变速恒频风力发电系统的发展现状，阐述了定桨距型和变桨距风力发电系统的功率调节原理，综述了风力发电技术的发展趋势。然后，对风力发电机组的励磁系统做了简要的概述，在比较了多种励磁方案后设计了无刷励磁控制系统。紧接着，论文分析了系统要求，通过比对当前开关器件功率水平、成本以及控制策略，选择了不控整流和PWM逆变的变流系统。在对不同滤波器结构的并网变流器控制系统进行研究后，提出了“直接电流控制”方法对网侧变流器进行控制，根据直接电流控制原理建立了 PWM逆变器的数学模型，并通过Matlab/Simulink仿真验证了控制方法的正确性。
关键词：风力发电，变速恒频，并网变流器，变流技术
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The Research on the Power Electronic Conversion Technique of
Wind Power Generation Systems
ABSTRACT
Wind power converter system is the equipment which translate the wind generator output power into constant voltage constant-frequency power, is an important component part in the wind power system. Wind power converter system has the characteristic functions as follows: fast and dynamical adjusting the parameters, such as voltage, current, real power, reactive power and so on, improve the power factor, reduction of the grid harmonic pollution, is the current focus of the Wind power technology study. This paper analysis the wind power generation’s structure, working principle and key technologies, designed the converter of 850 kilowatt wind power generation systems.
At first, this paper introduces the background and significance of the wind power converter technology, introducing details of the wind power generation system’s composition and working principle. Then introduce the status of VSCF wind power generation system, analyses the Principle of stall regulation and pitch regulation system. Secondly, this paper introduced the excitation system of wind power generation roughly, and then chooses the Brushless Excitation system following compare many kinds of excitation systems. Following, this paper analyses the requirement of system and practical condition, and so select the uncontrolled rectifying and PWM inverter system. According to different out-filter used in grid-connected inverter, different current control strategy by using different variable is compared. Then this paper proposes a ‘DIRECT CURRENT CONTROLL STRAREGY ’, and
establishes the PWM inverter model. In the last, this paper confirmed the control method accuracy
through the Matlab/Simulink simulation.
KEY WORDS: wind power, VSCF, grid-connected inverter, Converter Technology
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目 录
摘 要 ········································································································ I ABSTRACT ·································································································· II 1 绪论 ······································································································ 1
1.1 风力发电系统中变流技术研究的背景和意义··········································· 1 1.2 风力机的运行原理 ············································································ 2 1.3 风力发电系统的结构 ········································································· 3
1.3.1 动力传输 ················································································ 3 1.3.2 风力发电系统的基本结构 ·························································· 4 1.4 国内外风力发电控制系统 ··································································· 6
1.4.1 变速恒频风力发电系统 ····························································· 7 1.4.2 风力发电系统的功率调节方式 ··················································· 10 1.4.3 风电技术的发展趋势 ······························································· 12 1.5 本文的研究内容 ·············································································· 12 2 同步发电机简述 ······················································································ 14
2.1 同步发电机的结构 ··········································································· 14
2.1.1同步发电机结构模型 ································································ 14 2.1.2 同步发电机结构型式 ······························································· 15 2.2同步发电机工作原理 ········································································· 15 2.3 同步发电机的空载特性 ····································································· 16
2.3.1 相关知识 ··············································································· 16 2.3.2 空载特性的测定 ······································································ 17 2.4 风力发电系统的的负载特性 ······························································· 18 2.5 小结 ····························································································· 21 3 同步风力发电机励磁系统 ·········································································· 22
3.1 同步发电机励磁系统概述 ·································································· 22 3.2同步发电机励磁系统分类··································································· 24
3.2.1直流励磁机励磁方式 ································································ 24 3.2.2它励交流励磁机方式 ································································ 25 3.2.3 无刷励磁方式 ········································································· 26 3.2.4 静止励磁方式 ········································································· 27 3.3 对励磁系统的基本要求 ·································································· 28 3.4 励磁系统设计方案 ········································································· 28 3.5 小结 ···························································································· 30
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4 风力发电系统中的电力电子变流技术 ··························································· 31
4.1 系统的需求分析和总体设计方案 ····················································· 31
4.1.1 850千瓦风力发电变流系统的需求分析 ········································ 31 4.1.2 850千瓦风力发电机的技术参数 ················································· 31 4.1.3 主电路结构设计 ······································································ 32 4.1.4 工作原理 ··············································································· 32 4.1.5 逆变系统结构图 ······································································ 33 4.2 三相电压型PWM并网变流器设计和控制原理 ····································· 34
4.2.1 并网变流器电流控制方法 ························································· 34 4.2.2 直接电流控制原理··································································· 35 4.2.3 并网变流器电流环设计 ···························································· 35 4.3 PWM逆变器的数学模型 ··································································· 37
4.3.1 逆变器相关知识以及滤波电感的选择 ·········································· 37 4.3.2 PWM逆变器的数学分析 ····························································· 38 4.4 坐标变换的相关知识 ········································································ 40 4.5 相关参数参考值 ·············································································· 41 4.6 仿真中用到的几个模型的建立 ························································· 42
4.6.1 变流器结构 ············································································ 42 4.6.2 滤波环节 ··············································································· 43 4.6.3 控制模块 ··············································································· 43 4.7 变流器的的仿真分析 ········································································ 45 4.8 小结 ···························································································· 47 结论与展望 ······························································································· 48 致 谢 ······································································································· 49 参 考 文 献 ······························································································ 50 附录 ········································································································ 51
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