三相LCL并网变换器控制方法研究

发布时间：2018-06-20 06:49

本文选题：LCL并网变换器 + 阻尼损耗　；参考：《天津大学》2014年硕士论文

【摘要】：在当今世界经济发展的大环境下,社会对电力的需求日益增加,化石能源的短缺问题与其所造成的环境污染问题引起越来越多国家的关注,基于可再生能源的分布式发电并网技术以良好的发展前景成为研究的方向。作为可再生能源分布式并网系统的重要组成,并网变换器的结构及其控制策略研究是技术推广应用的关键部分之一,正引起广泛的关注。本文对三相LCL并网变换器系统进行研究,研究内容包括:滤波器参数关系研究与优化设计,系统控制策略研究和无电网侧电压传感器的设计。首先对LCL滤波器部分重要参数之间的关系进行分析,以阻尼电阻上的损耗最小为目标确定电感的取值比,并对LCL滤波器的其他参数进行设计。其次,针对传统电网电压定向矢量控制方法存在的计算量大,控制结构复杂等问题,在三相ABC静止坐标系、两相dq静止坐标系及两相旋转坐标系下建立LCL滤波三相并网变换器的数学模型,采用瞬时功率外环逆变器侧电流内环的恒频准直接功率控制策略的双闭环控制策略对并网变换器进行控制,设计PI控制器实现恒频准直接功率控制。最后将滑模变结构理论引入LCL并网变换器的直接瞬时功率控制方法中。采用有功功率和无功功率构建滑模变量,并利用带有Slid函数的指数趋近律来削弱抖振,实现LCL并网变换器系统的单位功率因数运行,有效地滤除输出电流的高次谐波。为进一步提高系统稳定性,在直接瞬时功率控制算法中引入虚拟磁链变量,采用改进型一阶低通滤波器设计虚拟磁链观测器,取消电网侧电压传感器,实现对系统的无电网侧电压传感器控制。仿真实验结果表明了无电网侧电压传感器的滑模变结构直接瞬时功率控制策略具有良好的稳定性和动态响应性。
[Abstract]:With the development of the world economy, the demand for electricity is increasing day by day. The shortage of fossil energy and the environmental pollution caused by fossil energy have attracted more and more countries' attention. Distributed generation grid technology based on renewable energy has become the research direction with good development prospect. As an important component of renewable energy distributed grid-connected system, the structure and control strategy of grid-connected converter is one of the key parts of technology popularization and application. In this paper, the three-phase LCL grid-connected converter system is studied. The research contents include: filter parameter relationship research and optimization design, system control strategy research and no grid side voltage sensor design. Firstly, the relationship between some important parameters of LCL filter is analyzed, and the value ratio of inductor is determined by taking the minimum loss on damping resistance as the target, and the other parameters of LCL filter are designed. Secondly, aiming at the problems of large computation and complex control structure in the traditional voltage oriented vector control method of power network, in the three-phase ABC stationary coordinate system, The mathematical model of LCL filter three-phase grid-connected converter is established in two-phase dq stationary coordinate system and two-phase rotating coordinate system. The double closed loop control strategy of constant frequency quasi direct power control strategy of instantaneous power outer loop inverter side current inner loop is used to control the grid-connected converter. Pi controller is designed to realize the constant frequency quasi-direct power control. Finally, the sliding mode variable structure theory is introduced into the direct instantaneous power control method of LCL grid-connected converters. Active power and reactive power are used to construct sliding mode variables, and the exponential approach law with Slid function is used to weaken buffeting, realize unit power factor operation of LCL grid-connected converter system, and effectively filter out high-order harmonics of output current. In order to further improve the stability of the system, virtual flux variables are introduced into the direct instantaneous power control algorithm. The improved first order low-pass filter is used to design the virtual flux observer, and the voltage sensor on the power network side is eliminated. The control of the system without voltage sensor on the grid side is realized. The simulation results show that the sliding mode variable structure direct instantaneous power control strategy has good stability and dynamic response.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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