基于虚拟同步机的微网并网逆变器控制策略研究

发布时间：2018-02-25 21:16

本文关键词： 虚拟同步机并网逆变器功频控制虚拟励磁转动惯量　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：伴随国民经济发展与化石能源枯竭的矛盾越来越显著,以可再生能源为特色的分布式发电(Distributed Generation,DG)系统迅速占据了未来电力研究的关键位置。微电网(Micro-Grid,MG)提供了分布式发电系统应用的方式,并网逆变器作为连接微电网和大电网之间的纽带对微电网的运行情况有重要影响。并网逆变器由电力电子器件为主体构成,由此带来一系列不足,包括系统低输出阻抗、缺乏惯性、并网联运时的功率分配能力不足以及难以与现有电力系统的调控策略进行配合。本文以微网并网逆变器为研究对象,通过建立数学模型,详细分析其工作原理和特点。通过对微电网的结构分析与并网逆变器传统控制策略进行对比,研究传统的并网逆变器控制策略中的不足,并引入模拟同步发电机特性的虚拟同步机(Virtual Synchronous Generator,VSG)控制策略。针对传统电机与电力电子器件之间的差异,建立二阶同步电机数学模型,通过数学模型分析建立同步电机关键参数与逆变器电路中关键参数的对应关系,运用类比的思想建立两者之间联系,从而为控制策略提供理论依据与设计思路。对基于虚拟同步机的并网逆变器整体控制策略进行研究。首先,对同步电机调速器与励磁控制器原理进行分析,类比设计频率控制器与虚拟励磁控制器。接着对模拟的同步电机本地进行设计,借助幅值相角的转化引入复数形式的电阻电阻和同步电抗,实现模拟同步电机本体特性。之后在仿真平台上完成全系统模型搭建,研究系统工作时,不同工况下系统的动、稳态工作特性,分析验证转动惯量的作用,并通过和同步电机、下垂控制进行仿真对比,验证所设计的控制策略既可以模拟同步电机的外特性又能够克服下垂控制的不足。最后,设计并搭建一套LCL型三相并网逆变器实验平台,对平台硬件进行介绍,在硬件平台上进行初步实验验证,证明所采用的控制策略的有效性与可行性。
[Abstract]:The contradiction between the development of national economy and the depletion of fossil energy is becoming more and more obvious. The distributed Generation Generation (DG) system, which is characterized by renewable energy, has rapidly occupied the key position of the future electric power research. Microgrid Micro-GridMGG provides the application of distributed generation system. Grid-connected inverter, as a link between microgrid and large grid, has an important influence on the operation of microgrid. Grid-connected inverter is composed of power electronic devices, which brings a series of shortcomings, including low output impedance of the system. Lack of inertia, lack of power distribution ability and difficulty in coordination with the existing power system regulation strategy. This paper takes the microgrid grid-connected inverter as the research object, through the establishment of mathematical model, By comparing the structure analysis of microgrid with the traditional control strategy of grid-connected inverter, the shortcomings of the traditional control strategy of grid-connected inverter are studied. The control strategy of virtual Synchronous generator is introduced to simulate the characteristics of synchronous generator. Aiming at the difference between traditional motor and power electronic device, the mathematical model of second-order synchronous motor is established. The relationship between the key parameters of synchronous motor and the key parameters of inverter circuit is established by mathematical model analysis, and the relationship between them is established by analogy. The whole control strategy of grid-connected inverter based on virtual synchronous machine is studied. Firstly, the principle of governor and excitation controller of synchronous motor is analyzed. The analog design of the frequency controller and the virtual excitation controller is followed by the local design of the simulated synchronous motor, and the complex resistance and synchronous reactance are introduced with the help of the transformation of the amplitude and phase angle. The whole system model is built on the simulation platform to study the dynamic and steady operating characteristics of the system under different operating conditions, and to analyze and verify the role of the moment of inertia. The sagging control is simulated and compared to verify that the designed control strategy can not only simulate the external characteristics of synchronous motor but also overcome the shortcomings of droop control. Finally, a set of experimental platform of LCL type three-phase grid-connected inverter is designed and built. The hardware of the platform is introduced, and the preliminary experiment is carried out on the hardware platform, which proves the effectiveness and feasibility of the control strategy.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM464

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