| 题名 | 基于LCL滤波器拓扑的双馈风力发电机网侧变流器的研究; 基于LCL滤波器拓扑的双馈风力发电机网侧变流器的研究 |
| 作者 | 1张宪平,电工研究所 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-31 |
| 授予单位 | 中国科学院电工研究所 |
| 导师 | 1许洪华,电工研究所 |
| 关键词 | LCL滤波器 网侧变流器 有源阻尼 电压不平衡 谐波畸变 复合控制 LCL filter, grid-side converter, active damping, unbalanced voltage, harmonics distortion, compound control |
| 其他题名 | 基于LCL滤波器拓扑的双馈风力发电机网侧变流器的研究 |
| 中文摘要 | 风力发电作为一种已获得商业化利用并具有较大潜能的可再生能源开发方式，近年来得到了较快的发展，其中变速风力发电技术中的双馈型变速恒频风力发电技术以其独特的优势而备受关注。然而，目前我国在大功率双馈风电机组变流器的研制方面还存在着技术不足，普遍采用的单电感L滤波的三相电压源型PWM整流器拓扑，在开关频率、效率、体积和成本等方面存在的问题越来越制约着其发展。三阶LCL滤波器可以减少总电感量，有利于降低成本，减小装置的体积和重量，较适用于大容量电机驱动、交直流电力传输等场合，这使得基于LCL滤波器拓扑的变流器成为研究热点。本文对LCL滤波器在双馈风力发电机网侧变流器系统中的应用进行了深入研究，内容主要包括变流器的建模与特性研究、变流器的控制策略及系统设计、电压不平衡和畸变情况下变流器的控制、LCL滤波器的参数设计等。 首先，建立了LCL滤波的网侧变流器开关数学模型和开关周期平均模型，利用小信号线性化理论给出了变流器的小信号交流模型，对变流器的静态和动态特性进行了深入分析，得出了其在频率、交流侧相量关系和功率等方面的特点，为变流器控制系统的设计和分析提供了理论基础。 其次，利用LCL滤波器的低频特性，提出了基于电网电压定向的双闭环矢量控制策略，内环控制电流的有功、无功分量，外环控制直流电压的稳定。为获得良好的变流器控制效果，在文中详细给出了电流内环和电压外环调节器参数的设计过程。分析结果表明：设计出的调节器参数能够确保系统在低频具有良好的阻尼比。 为了避免LCL滤波器谐振破坏系统的高频稳定性，在对无源阻尼策略分析的基础上，论文针对不同电流控制结构下的有源阻尼策略进行了研究。在变流器采用网侧电流闭环控制结构时，提出了利用滤波电容电流配置控制对象极点以抑制LCL滤波器谐振的有源阻尼策略。通过LCL滤波器网侧电流和电容电流的函数关系，将电容电流乘以比例和相位补偿环节后，对调制电压进行校正，增大了控制对象高频极点的阻尼比。在变流器侧电流闭环控制结构时，分析了虚拟电阻控制策略的原理，提出了在系统中存在采样延迟和调节器等环节时的改进虚拟电阻策略方案。利用虚拟电阻策略下电流闭环传递函数和LCL滤波器加入电阻时的等效性，推导出了受采样延迟和PI调节器参数影响的虚拟电阻环节传递函数，并利用电容电流和电压函数关系，对虚拟电阻环节进行了简化处理。仿真与实验结果表明：文中提出的两种有源阻尼策略可有效地抑制LCL滤波器的谐振。 第三，在电网电压不平衡和畸变情况下，直接利用理想电压情况下的控制方法将使变流器的控制性能变差，甚至无法正常工作。论文建立了网侧变流器在电网电压不平衡和畸变情况下的数学模型，详细分析了直流侧谐波电压的特点及电网电压畸变对交流电流的影响。从系统瞬时输入输出功率出发，通过将网侧二次谐波功率和平均无功功率置零，给出了变流器网侧电流指令算法。为了在正序同步旋转坐标系下实现对正负序电流的独立控制和低次谐波的抑制，文中首次提出了基于PI和重复控制器的电流复合控制策略，并给出了复合控制器的设计方法及相关仿真、实验验证的结果。 第四，设计出合适的LCL滤波器参数对网侧变流器非常重要，文中首先从变流器的交流相量关系、主要谐波分布、功率因数等角度出发给出了电感、电容和滤波器谐振频率的限制条件。利用电流的纹波限制要求给出了变流器侧电感的设计公式，通过LCL滤波器各参数间的关系推导出了网侧电感和滤波电容的简化设计公式。仿真和实验结果表明LCL滤波器的滤波效果要明显高于L滤波器。 最后，在实验室搭建了一台5KVA的基于LCL滤波器拓扑的网侧变流器实验平台。具体包括：核心部件的选择和系统总体硬件设计，基于TMS320LF2407A的DSP控制系统开发，进行了相关的实验。实验结果验证了滤波器设计的有效性和系统控制策略的正确性。 As a renewable energy technology already commercially available and with great potential to be further exploited, wind power experienced fast development in the recent years. The variable speed constant frequency (VSCF) wind power generation technology, especially doubly-fed induction generator (DFIG) type wind power systems based VSCF attract big attention for their exclusive advantages. However, there is technical deficiency at high power converters in doubly-fed wind turbine system. As the application of voltage source pulse width modulating (PWM) rectifier with single L filter used in wind energy generation, the problems such as high switching frequency, efficiency, capacity and cost have restricted its development. The third-order LCL filter can reduce the total inductance, the device size, and weight with low costs when the same harmonics content required, and it is more appropriate to be used in the high-power applications such as motor drive and ac/dc power transmission. Therefore, this dissertation gives systematically study on grid-side converter with LCL filter for doubly-fed induction generator in wind power. The contents mainly include the mathematical model and characteristics of converter, control strategy and design of system parameters, control of converter under unbalanced and distorted grid voltage conditions, and design of LCL filter parameters and so on. Firstly, the switching mathematical model and average switching cycle model of converter with LCL filter have been founded. With small-signal linearization method, the steady-state and dynamic mathematical model of converter are given, and static and dynamic characteristics are analyzed. These analyses establish theoretical foundation for the successive research on control system analysis and design in the dissertation. Secondly, with low-frequency characteristics of LCL filter, the grid voltage-oriented vector control with double closed loops is proposed for converter. To get good control effect, the PI regulator parameters of AC current and DC voltage loops are designed, and then the parameters are adjusted for stability of converter with LCL filter. The analytical results show that the parameters of regulators designed can make sure stability of converter below resonant frequency. The resonance of LCL filter may cause instability of system, the passive resistors can improve damping ratio of poles in high frequency. However, power loss can’t be ignored by damping resistors. Therefore, the active damping strategies have been studied. In the grid –side current closed-loop control structure, the capacitor current is used to change poles placement of LCL filter, and sampling delay is compensated by lead filter. When the converter-side current is used as feedback control, the virtual resistance strategy has been analyzed and improved to enhance the effectiveness of virtual resistance strategy. The simulation and experimental results show that the active damping strategies proposed can damp resonance of LCL filter effectively. Thirdly, under unbalanced and distorted gird voltages, if control methods of ideal voltages are employed directly in the grid-side converter，the input and output performance of the converters will deteriorate, even work failure. To improve performance of converter with LCL filter under unbalanced and distorted grid voltage conditions, the mathematical model of converter has been established, and characteristics of the DC voltage harmonics and the influences of distorted voltage on converter are discussed. After ac power of converter is analyzed in detail, the current reference values for eliminating even harmonics of DC voltage are given. For realizing control of positive and negative sequence currents and low order harmonics eliminated, the current control system with compound controller is proposed firstly in the positive sequence synchronous rotating coordinate system, and the design steps of compound controller are introduced. Finally, the simulation and experimental results are given to verify the strategies proposed. Fourthly, it is very important to design suitable LCL filter parameters for converter. After harmonics of converter are analyzed firstly, the constraints of inductances, capacitances and resonant frequency are got from operating conditions, harmonics and power factor of converter. The relationship between capacitance and inductance are derived, and some simple formulas for design of LCL filter are given. The simulation and experiments show that LCL filter can filter high order harmonics effectively. Finally, the experimental system of one 5 KVA grid-side converter with LCL filter has been set up. The specific content include design of hardware and software, the development of DSP control system based TMS320LF2407A, and related experiments. The experimental results show that design of LCL filter and control strategies proposed in this paper are right. |
| 语种 | 中文 |
| 公开日期 | 2010-10-18 |
| 页码 | 185 |
| 分类号 | TM1;TM921 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.iee.ac.cn/handle/311042/6826]  |
| 专题 | 电工研究所_其他部门_其他部门_博士学位论文 |
| 推荐引用方式 GB/T 7714 | 1张宪平,电工研究所. 基于LCL滤波器拓扑的双馈风力发电机网侧变流器的研究, 基于LCL滤波器拓扑的双馈风力发电机网侧变流器的研究[D]. 中国科学院电工研究所. 2009. |
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