无线并联逆变系统按容分配负荷的研究

发布时间：2018-03-27 06:19

本文选题：微电网无线并联　切入点：下垂控制　出处：《南昌航空大学》2017年硕士论文

【摘要】：伴随着人类对能源需求量的不断增加以及传统化石能源的枯竭,新能源的开发和利用越来越受到人们的青睐。太阳能分布式发电以拥有巨大资源、无污染等优点在世界各地得到广泛应用。作为分布式发电系统关键技术—逆变器并联技术越来越受到学术界的关注,使用下垂控制的无线并联技术以冗余度高、接线较少等优点而优于其他并联控制方式。但在分布式发电系统中具有容量大小不等逆变器并联。为了使各个逆变器得到合理的利用,就需要对不同容量的逆变器进行合理负荷分配。针对这一点本文展开了重点讨论与分析,基于下垂控制原理,对逆变电源输出电压的幅值和频率进行了动态分析,得到了系统收敛的临界下垂系数以及不同容量逆变器并联时按容分配负荷的充分条件。本文首先介绍了单相全桥逆变器的工作原理,并对其进行数学建模以及控制策略进行设计。包括电压环和电流环参数的选取和带非线性负载时算法的改进。同时搭建仿真平台对控制策略的有效性进行验证。其次在不同容量逆变器无线并联时按容分配负荷上进行了重点研究。首先建立并联电路系统模型,对引入的下垂控制原理进行介绍;然后基于下垂控制方程,联立经过滤波后的逆变器输出功率方程,组成逆变器输出电压幅值和频率的动态方程组,对逆变电源的输出电压的幅值和频率收敛性进行分析,同时得到逆变电源按其自身容量分配负荷的一个充分条件,最后搭建仿真和实验平台对不同容量逆变器并联按容分配负荷的充分条件进行验证。最后对系统的硬件和软件进行设计。在硬件上,主要涉及直流母线电容和开关管型号的选取、驱动电路和缓冲吸收电路的设计以及LC滤波电路的参数的选取;在软件上,主要涉及系统的主程序和中断程序流程图介绍、低通滤波器和重复控制的离散化、PI算法的数字化及输出阻抗的设计。对其中的输出阻抗设计进行仿真和实验,验证引入具有带通滤波器的虚拟阻抗可以减小系统的奇次谐波阻抗,使系统带非线性负载时电压畸变率大大减小。
[Abstract]:With the increasing demand for energy and the depletion of traditional fossil energy, the development and utilization of new energy is becoming more and more popular. The advantages of pollution-free are widely used in the world. As the key technology of distributed generation system, inverter parallel technology has been paid more and more attention by academic circles, and the use of droop control wireless parallel technology has high redundancy. It is better than other parallel control methods because of less connection, but in distributed generation system, there are parallel inverters with different capacity. In order to make each inverter get reasonable utilization, This paper focuses on the discussion and analysis of the load distribution of inverter with different capacity. Based on the droop control principle, the amplitude and frequency of the output voltage of the inverter power supply are dynamically analyzed. The critical sag coefficient of convergence of the system and the sufficient condition of load distribution according to capacity when inverters of different capacities are connected in parallel are obtained. Firstly, the working principle of single-phase full-bridge inverter is introduced. The mathematical modeling and control strategy are designed, including the selection of voltage loop and current loop parameters and the improvement of algorithm with nonlinear load. At the same time, a simulation platform is built to verify the effectiveness of the control strategy. Secondly, the paper studies the load distribution according to the capacity of different capacity inverters in wireless parallel connection. Firstly, the parallel circuit system model is established. Based on the droop control equation, the output power equation of the inverter after filtering is established to form the dynamic equations of the output voltage amplitude and frequency of the inverter. The amplitude and frequency convergence of the output voltage of the inverter power supply are analyzed. At the same time, a sufficient condition for the inverter power supply to distribute the load according to its own capacity is obtained. Finally, a simulation and experimental platform is built to verify the sufficient conditions for parallel load distribution of inverters with different capacities. Finally, the hardware and software of the system are designed. It mainly involves the selection of DC busbar capacitance and switch type, the design of drive circuit and buffer absorption circuit, and the selection of parameters of LC filter circuit. In software, the main program and interrupt program flow chart of the system are introduced. The digitization of low pass filter and discrete Pi algorithm of repetitive control and the design of output impedance. The design of output impedance is simulated and tested. It is verified that the introduction of virtual impedance with bandpass filter can reduce the odd harmonic impedance of the system and reduce the voltage distortion rate of the system with nonlinear load.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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