分类号 密级 U D C 编号 10486
武 汉 大 学 硕 士 学 位 论 文
基于PSCAD的变速恒频双馈风力发电系
统建模与仿真
研 究 生 姓 名：李晓龙 学 号：2010202070022 指导教师姓名、职称：
学 科、专 业 名 称：电力系统及其自动化 研 究 方 向：电力系统运行与控制
二〇一二年五月
Modeling and Simulation of Variable Speed Constant Frequency Doubly Fed Induction Generator Wind Power System Based on
PSCAD
Li Xiao-long
May, 2012
郑重声明
本人的学位论文是在导师指导下独立撰写并完成的，学位论文没有剽窃、抄袭、造假等违反学术道德、学术规范和侵权行为，否则，本人愿意承担由此而产生的法律责任和法律后果，特此郑重声明。
学位论文作者（签名）：年
日
月摘要
在常规能源日益枯竭和能源环境效益愈发凸显的今天，可再生清洁能源越来越受到人们的关注，风能则是可再生清洁能源中的典型代表。全球蕴含有十分丰富的风力资源，取之不尽用之不竭且对环境不会造成污染，因而各国都对风力发电技术展开了大量研究并取得了很多的成果。其中，变速恒频双馈风力发电技术只需采用较小容量的变换器，在输入风速变化情况下能够维持输出的恒定，实现有功功率和无功功率可以实现独立解耦控制，有利于维持电网稳定并能提高电能质量，是目前大功率风力发电机组的主流技术和研究热点。
本文以双馈风力发电机为主要研究对象，介绍了双馈电机的基本结构特点及其运行原理，详细推导分析了三相静止abc坐标系下和两相同步旋转dq坐标系下双馈发电机的动态数学模型，在此基础上，采用了基于定子磁链定向的矢量控制方案对转子侧变换器的控制方案进行设计，将滞环电流PWM控制技术引入其中，建立了转子电流与功率之间的控制关系。采用转速与无功功率双闭环的控制结构，较好的实现了有功功率和无功功率的解耦控制。网侧变换器的控制方案采用了SVPWM控制技术，通过电压电流双闭环的控制结构，能够维持直流侧母线电压恒定以及保持单位功率因数运行。在PSCAD/EMTDC电力仿真软件中搭建了双馈风力发电系统模型以及控制部分模型，仿真运行结果表明，双馈风力发电系统能够较好地追踪风能，实现最大功率输出，有功功率和无功功率能够实现独立调节，实现了解耦控制，网侧变换器能够较好地维持直流侧母线电压的恒定，从而验证了所搭建模型是正确的，所采取的控制策略是有效的。
最后介绍了低电压穿越的概念以及电网正常运行对风电机组低电压穿越能力提出的要求。介绍了实现低电压穿越的两大类技术，通过分析比较指出，在电网电压大幅跌落情况下，仅仅改进控制策略对实现低电压穿越不能起到应有的作用，硬件保护电路是必须增加的。介绍了目前普遍采用的转子侧增设Crowbar保护电路的方案以及Crowbar保护电路的概念和分类。在PSCAD中搭建了主动式Crowbar保护电路，通过仿真结果证明在电网电压大幅跌落的情况下投入Crowbar保护电路能够增强双馈电机的低电压穿越能力。
关键词：风力发电；双馈电机；变速恒频；PSCAD/EMTDC；低电压穿越
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Abstract
As the increasing depletion of conventional energy sources and energy environmental benefits become more prominent, renewable clean energy gets more and more attentions, and wind energy is a typical representative of renewable clean energy. Global containing plenty of wind resources, which is inexhaustible and won’t cause any pollution, so many countries has studied a lot on wind power technology and made many achievements. Among those technologies, the VSCF doubly-fed wind power generation technology, whose converter capacity is much smaller, is currently the mainstream used in high-power wind turbine technology and research. It can maintain the output constant in the case of variable input wind. The active and reactive power can be achieved independent decoupling control. It’s also conducive to the maintenance of the grid stable and can improve power quality.
The doubly-fed wind generator is the main object of study in this paper. The basic structural features of the doubly-fed machine and its operating principle is introduced. The detail dynamic mathematical model in both three-phase stationary coordinate and two-phase synchronous rotating coordinate system is derived. The rotor side converter control scheme is designed based on the stator flux oriented vector control scheme. The hysteresis current PWM control technology is used and the control relationship between rotor current and output power is established. Speed and reactive power closed-loop control structure is used to achieve a better decoupling control of active power and reactive power. The line-side converter control scheme is based on SVPWM control technology with voltage and current double closed loop control structure, which can help to maintain the DC side of the bus voltage constant and to maintain unity power factor operation. Doubly-fed wind power generation system model and the control model are set up in the electric power simulation software PSCAD / EMTDC. The simulation results show that the doubly-fed wind power generation system can track the wind and achieve maximum power output, and active power and reactive power can be adjusted independently to achieve a decoupling control. The line-side converter is better able to maintain the DC side of the bus voltage constant. The result proves that the model is correct and the control strategy adopted is effective.
Finally, the concept of grid of low voltage ride through and the request for the low voltage ride through capability of wind turbine is described. Two major categories of low voltage ride through technology are introduced. By analyzing and comparing,
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