基于三相四线制多功能并网逆变器的协同控制策略研究

发布时间：2018-02-12 18:57

本文关键词： 微电网三相四桥臂并网逆变器多功能并网逆变器电能质量优化补偿 RT-lab　出处：《重庆理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着能源危机和社会问题的加剧,新能源的开发和利用得到了有效的发展。以风、光等新能源为主的发电技术日益成熟,大型的风、光电厂大量投入使用。但是对于小容量的风、光等分布式发电,如何将其有效的接入电网而不对电网带来无功和谐波的影响,这是目前研究的热点之一。为了实现分布式发电与电网的连接,提出了微电网的概念,微电网是集各种可再生能源发电、微电网的监控和保护、就地负载为一体的局部供电系统,是小型分布式发电并网的核心环节。为了减小分布式发电并网对电网造成无功和谐波的影响,传统的方法是使用无源滤波器来补偿电网所需的无功和谐波。考虑到其滤波效果差、无功补偿定量等缺点,有源电力滤波器(Active Power Filter,APF)、无功静止补偿器(Static Var Compensator,SVC)和静止无功发生器(Static Var Generator,SVG)等有源补偿设备得到了广泛的使用。但是有源滤波装置一般价格昂贵,对于小型的新能源分布式发电来说这会增加成本,不利于设备维护。不难发现在微电网中大量使用到了并网逆变器,如果能够使并网逆变器在并网逆变的同时来补偿微电网并网对电网造成的无功和谐波影响,就能在不增加成本的情况下来提高并网点的电能质量。观察并网逆变器和APF的主电路结构,可以发现他们具有相同的拓扑结构,二者功能不同主要是因为其控制方式不同。本文主要研究内容是利用微电网中的逆变器在并网逆变的同时具有治理微电网自身无功和谐波的功能,以减小微电网对低压配电网电能质量的影响。本文的研究对象为三相四桥臂并网逆变器,使其在实现新能源并网发电的同时治理微电网的无功、谐波和不平衡电流。本文首先对研究内容的背景和意义进行阐述,分析现阶段研究存在的一些问题,并在后面章节对研究内容进行详细介绍。然后,分析三相四桥臂并网逆变器的拓扑结构,建立起相应的数学模型。分析逆变器的控制方式,着重介绍其指令电流的生成算法。指令电流可以分为两部分,一为并网电流指令;二为谐波电流指令。并网电流指令的作用是控制逆变器进行并网发电,谐波电流指令的作用是控制逆变器进行微电网电能质量治理。最后,在多功能逆变器的基础上实现电能质量的优化补偿,使逆变器的利用效率更高。本文利用MATLAB/Simulink对整个逆变系统进行搭建。对既能实现并网逆变又能实现电能质量治理的控制算法进行仿真验证,并对随后提出的电能质量优化补偿策略进行仿真验证。最后使用RT-lab对本文所提的控制算法和补偿策略进行仿真试验。MATLAB和RT-lab仿真试验结果验证了本文控制策略的正确性和有效性。
[Abstract]:With the aggravation of energy crisis and social problems, the development and utilization of new energy have been effectively developed. But for the distributed generation of small capacity wind, light and so on, how to effectively connect it to the power grid without bringing reactive power and harmonic effects to the power network, In order to realize the connection between distributed generation and power grid, the concept of microgrid is proposed. Microgrid is a collection of renewable energy generation, monitoring and protection of microgrid. The local power supply system with local load as an integral whole is the core link of small distributed generation and grid connection. In order to reduce the impact of distributed generation and grid connection on reactive power and harmonic, The traditional method is to use passive filter to compensate the reactive power and harmonic of power network. Active Power filter (APF), static Var compensator (SVC) and static Var generator (SVG) are widely used. For small, new energy distributed generation, this increases costs and is not good for equipment maintenance. It is not difficult to find that grid-connected inverters are widely used in microgrids. If the grid-connected inverter can be used to compensate the reactive power and harmonic effects caused by the grid-connected microgrid at the same time, We can improve the power quality of parallel nodes without increasing the cost. If we look at the main circuit structure of grid-connected inverter and APF, we can find that they have the same topology. The main purpose of this paper is to use the inverter in the microgrid to control the reactive power and harmonics of the microgrid while the inverter is connected to the grid. In order to reduce the influence of microgrid on the power quality of low-voltage distribution network, the research object of this paper is three-phase four-leg grid-connected inverter, which can realize the grid connection of new energy and control the reactive power of microgrid at the same time. Harmonic and unbalanced current. The background and significance of the research content are described in this paper, and some problems existing in the present research are analyzed, and the research contents are introduced in detail in the following chapters. The topology structure of three-phase four-leg grid-connected inverter is analyzed and the corresponding mathematical model is established. The control mode of inverter is analyzed and the algorithm of generating instruction current is introduced emphatically. The instruction current can be divided into two parts: one is grid-connected current instruction; The second is harmonic current instruction. The function of grid-connected current instruction is to control the inverter for grid-connected generation, and the function of harmonic current instruction is to control the inverter to deal with the power quality of micro-grid. Finally, The power quality compensation is realized on the basis of multifunctional inverter. In this paper, MATLAB/Simulink is used to build the whole inverter system. The control algorithm which can not only realize grid-connected inverter but also realize power quality governance is verified by simulation. Finally, the simulation results of the proposed control algorithm and compensation strategy by RT-lab. MATLAB and RT-lab simulation results verify the correctness and effectiveness of the proposed control strategy.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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