【作者】 陈瑶；

【导师】 金新民；

【作者基本信息】 北京交通大学 ， 电力系统及其自动化， 2008， 博士

【摘要】 直驱型风电机组因其具有能量转换效率高、可靠性高、并网功率控制灵活等优点,成为了继双馈型风电机组之后风力发电技术领域的重要研究方向。然而,对于目前主流的兆瓦级直驱型风电机组而言,我国在变流机组及其核心控制技术方面仍依赖进口,极大制约了风电产业的进一步发展。因此,本文围绕直驱型风电机组全功率并网变流技术展开理论研究,对网侧变流器和电机侧变流器的设计方法与控制策略进行分析探讨,并通过仿真和实验验证了理论研究成果的正确性。首先,研究了网侧变流器的数学模型与控制策略。建立了三相电压型PWM整流器的数学模型和等效电路;对比分析了电压定向控制、直接功率控制、虚拟磁链定向控制和虚拟磁链-直接功率控制等四种控制策略的工作原理和优缺点。其次,研究了网侧谐波分析与抑制问题。在谐波分析方面,提出了一种通用型谐波分析算法,并基于此对四种常用PWM发生方式下的电压谐波分布及其随调制参数的变化规律进行了对比分析;在谐波抑制方面,提出了一种新颖的网侧LCL滤波器设计算法,阐述了各滤波元件的计算步骤以及配合取值原则。第三,研究了网侧变流器的有中线运行控制问题。建立了有中线拓扑数学模型和等效电路;研究了零序电流控制和直流电压平衡控制策略;提出并证明了有中线系统即三维矢量空间中SPWM和SVPWM算法的本质一致性,并基于此对有中线变流器的网侧谐波抑制能力和直流电压利用率问题进行了综合分析。第四,研究了网侧变流器的并联运行控制问题。对比分析了直接并联和交错并联的工作原理和谐波抑制效果;阐述了交错并联情况下高频环流和低频振荡环流的产生机理;并对基于二维SVPWM、三维SPWM以及改进型SVPWM的交错并联控制策略进行了对比分析。第五,研究了基于被动整流拓扑的电机侧变流器控制问题。研究了升压斩波器基于电压前馈的电流跟踪控制策略;给出了基于最大功率跟踪原理的斩波器输入电流指令解析表达式;提出了N重交错并联升压斩波器总电流纹波统一算法,并基于此推导得出了N重交错并联时输入滤波电感的统一计算公式。第六,研究了基于主动整流拓扑的电机侧变流器控制问题。建立了永磁同步电机的数学模型和等效电路,对比分析了零d轴电流、恒定气隙磁链和最大效率三种控制目标下,永磁同步电机矢量控制策略的工作原理及优缺点。作为对理论分析结果的仿真验证,本文搭建了基于被动整流拓扑的1.5MW直驱型风电机组仿真模型,对包括最大功率跟踪控制、交错并联升压斩波器的纹波分析算法以及恒速运行控制在内的系统整体设计和控制方案进行了验证;搭建了基于主动整流拓扑的1.5MW直驱型风电机组仿真模型,对机组变速运行和恒速运行阶段,全功率变流器控制策略的稳态和动态性能进行了验证。作为对理论分析结果的实验验证,本文通过15kW网侧变流器实验样机,验证了所提出的通用型谐波分析算法和网侧LCL滤波器设计算法的正确性;通过兆瓦级能量互馈型风力发电变流器实验平台,考核了网侧变流器和电机侧变流器控制策略的稳态和动态性能,并对包括网侧变流器零序电流控制、交错并联网侧谐波抑制、并联环流控制策略、斩波器纹波分析算法和基于电压前馈的电流跟踪控制策略等方面在内的理论研究成果进行了验证。更多还原

【Abstract】 Direct-driven wind generation system is considered to be an important research direction in wind generation technology area due to its superiorities of being gearless, no slip rings and brushes, flexible power control ability, etc. However, as to MW direct-driven wind turbine, the power converter and core control technologies are still relied on importing in our country, which significantly restricts further development of wind energy industry. Therefore, this dissertation gives theoretical study on full-scale grid-connected power conversion technology in direct-driven wind generation system. The design principles and control strategies of line-side converter and generator-side converter are both discussed comprehensively. Simulations and experiments demonstrate the correctness of the research results. Following are the major research works of this dissertation.Firstly, modeling and control of line-side converter have been discussed. Mathematical model and equivalent circuit of line-side converter are established; The working principle, advantages and disadvantages of voltage oriented control, direct power control, virtual flux oriented control and virtual-flux-based direct power control are analyzed and compared in detail.Secondly, line-side harmonic analysis and suppression have been discussed. As to harmonic analysis aspect, a general harmonic analysis algorithm for line-side converter is proposed, and based on which, the variation rule of harmonic distribution under different PWM strategies or modulation parameters are compared and analyzed; As to harmonic suppression aspect, a novel design method of line-side LCL filter is proposed. The design procedures as well as cooperating calculation criteria of each filtering component are explained in detail.Thirdly, control of line-side converter with neutral point connected has been discussed. Mathematical model and equivalent circuit of topology with neutral point connected is established; Zero-sequence current control and dc-link voltage balancing control strategies are studied; The unification of SPWM and SVPWM algorithm in neutral-point-connected topology (3-dimention vector space) is proposed and proven, and based on which, the line-side harmonic suppression ability and dc-link voltage utilization problem of neutral-point-connected converter are analyzed comprehensively. Fourthly, control of parallel connected line-side converter has been discussed. Working principle and line-side harmonic elimination effect between directly parallel and interleaving parallel scheme are analyzed and compared; The generating mechanism of high frequency circulating current and low frequency oscillation circulating current under interleaving parallel scheme are both studied. Working principle of interleaving parallel control strategy based on 2d-SVPWM, 3d-SPWM and improved SVPWM are analyzed comprehensively.Fifthly, generator-side converter control based on reactive-rectify topology has been discussed. Current control strategy based on voltage feedforward scheme of boost converter has been studied; Expression of input current reference value for wind energy maximum power point tracking is obtained; Unified algorithm of total ripple current for N-cell interleaving parallel boost converter is proposed, based on which, unified design criteria for input inductance of N-cell interleaving parallel boost converter is obtained.Sixthly, generator-side converter control based on active-rectify topology has been discussed. Mathematical model and equivalent circuit of permanent magnetic synchronous generator is established; Working principle, advantages and disadvantages of zero d-axis current control, constant mutual flux linkage control and maximum efficiency control are analyzed and compared.As to simulation demonstration aspect, firstly, simulation model of 1.5MW direct-driven wind generation system based on reactive-rectify topology has been built, which demonstrates the effectiveness of system design and control scheme including maximum power point tracking control, ripple analysis algorithm of interleaving parallel boost converter, control strategy during constant speed phase, etc. Secondly, simulation model of 1.5MW direct-driven wind generation system based on active-rectify topology has been built, which demonstrates the steady state and dynamic response performance of control strategy of full-scale power converter.As to experiment demonstration aspect, firstly, 15kW line-side converter prototype has been built, which demonstrates the accuracy and feasibility of both general harmonic analysis algorithm and LCL-filter design algorithm. Secondly, MW energy feedback experimental platform for wind generation power converter has been built, which verifies the steady state as well as dynamic response performance of both line-side converter and generator-side converter control strategy, and demonstrates the correctness of theoretical research results including line-side converter zero-sequence current control, grid-side current harmonic suppression by interleaving parallel, circulating current control strategy in parallel scheme, boost converter ripple current algorithm, voltage feedforward based current control strategy, etc.更多还原