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1、风风力力发发电电网网侧侧变变流流器器控控制制策策略略研研究究摘摘 要要风力发电作为一种有效的可再生能源利用形式，近年来越来越受到关注，网侧变流器在 风电机组运行过程中 一直扮演着很重要的角色 。本文围绕网侧变流器的控制展开研究， 以带LCL型滤波器的三相电压型 PWM变流器（ LCL-VSC）拓扑作为网侧变流器研究对象。 首先在平衡电网条件下 建立了LCL-VSC的三相静止和两相旋转坐标系下的数学模型， 为控制策略分析 和控制系统设计提供了理论依据。 提出了风力发电应用中具有 LCL滤波器的网侧变流器的一种多环控制结构，该结构采用电压外环外加三个逐层利用的电流内环，实现稳定的直流电压以及电流的
2、前馈解耦和单位功率因数控制。 同时，给出了 基于复功率理论的电容电压估计方法 ，减少了传感器数量。为了在电网不平衡条件下对 LCL-VSC有效的控制，必须计算不平衡的正负序相位。 本文提出了一种新颖的基于电网不平衡的锁相思路，既可以计算正序相位角也可以计算负序相位角，用于 LCL-VSC的不平衡控制。这种方案的主要思路是：先从不平衡电网中提取出正负序分量，然后对正负序三相电压采用SFR-SPLL分别锁相，计算出正负序相位角。建立了在不平衡电网条件下 LCL-VSC的数学模型， 三相静止和两相旋转坐标系下的数学模型 。给出了 基于LCL滤波器的不平衡电流指令算法。按照不同的控制要求，可以分别实现
3、了电网不平衡时网侧电流对称控制，或者抑制直流侧二次纹波控制。完成了15kVA的LCL-VSC实验样机 平台的搭建和调试。通过仿真和 实验结果验证了理论分析与设计 的正确性 。关关键键词词： 风力发电； LCL；VSC；不平衡；多环控制Research on Control Strategy of Grid-side Converterfor Wind Power GenerationABSTRACTThe wind power generation is a kind of effective renewable energy source, which is received more an
4、d more attention in recent years. The grid-side converter plays a very important role in the wind power generation. This thesis does some research on control strategy of the grid-side converter, taking three-phase voltage source PWM converter with LCL filter (LCL-VSC) as the object of study. Firstly
5、, under the balanced voltage condition, LCL-VSC mathematical model is established in the three-phase static and two-phase rotate coordinates, to provide the theory for the control strategy analysis and the control system design. Then a multiloop control scheme is proposed for LCL-VSC. Within this sc
6、heme, 3 cascaded inner current loops along with an outer voltage loop are used to achieve stable dc-link voltage, currents decoupling and feedforward, as well as the unity power factor control. With this scheme, the capacitor voltage estimation is performed with complex power theory resulting the om
7、ission of the transducers for the capacitor voltage measurement. To control the LCL-VSC effectively under unbalanced grid condition, the positive and negative sequence phase should be calculated. This thesis proposed a novel phase locked loop (PLL) based on the unbalanced grid condition, which may c
8、alculate the positive sequence phase angle and the negative sequence phase angle, used for LCL-VSC unbalanced control. The main idea of this method is first to draw the posive and negative sequence components under the unbalanced grid condition, then to get the phases of positive and negative sequen
9、ce with the SFR-SPLL separately.The LCL-VSC mathematical model for unbalanced control is established under unbalanced grid condition. The reference current algorithm is given based on the LCL-VSC. For different purposes, it can be realized either symmetrical grid-side current or constant DC-side vol
10、tage without twice order ripple.Finally, a 15kVA LCL-VSC experimental system is established. The simulation and the experimental result verify the theoretical analysis and the design. Keywords: Wind power generation; LCL; VSC; unbalance; Multi-loop control目目 录录第第一一章章 绪绪 论论 .11.1论文的研究背景和选题意义 .11.1.1风
11、力发电及其意义 .11.1.2国内外风电产业发展概况 .11.1.3风力发电变流器的产业现状 .21.1.4论文的选题意义 .41.2风力发电中的网侧变流器研究现状.51.2.1风力发电中的电气系统 .51.2.2网侧变流器的拓扑结构 .71.2.3网侧变流器控制策略的研究现状.81.3本论文的主要目标和主要工作 .10第第二二章章 基基于于 LCL-VSC 网网侧侧变变流流器器 建建模模与与控控制制 .112.1引言 .112.2三相 LCL-VSC 数学模型 .112.2.1三相静止 (a , b, c)坐标系下的数学模型 .122.2.2两相静止坐标系 (D, Q)下的数学模型 .142.2.3两相旋转坐标系 (d, q)下的数学模型 .152.3LCL-VSC 多环控制策略 .162.3.1系统控制结构 .182.3.2并网电流指令算法 .192.3.3电流控制器设计与稳定性校验.212.3.4直流电压环控制器设计 .262.3.5基于复功率理论的电容电压估计 .272.4多环控制策略仿真与分析 .282.4.1电流环仿真 .292.4.2电压环仿真 .
