光伏并网逆变器零逆流控制系统的研究

发布时间：2019-03-26 08:52

【摘要】：由于光伏发电系统中含有较多的高次谐波,在并入大电网时,尽管有滤波装置,但仍有少量的谐波进入大电网,影响大电网的供电质量和安全稳定性。又由于目前正在大量推广建筑光伏的应用,倡导自发自用,当光伏系统所发的电能不能承担起负载的需求时,再由大电网提供。但是国家标准规定,不能有电能流向大电网。因此,本课题主要的研究内容就是如何控制流向电网的电流为0,即零逆流控制。本文首先叙述了研究的背景和研究意义,列出了光伏并网逆变器的几种传统控制方式以及逆功率的检测方法,分析了其中的优缺点,为下文介绍本课题所用的零逆流控制策略打下基础。然后分别在不同的坐标系下搭建零逆流控制系统的数学模型,并在对其进行一一分析之后确定光伏并网逆变器的电路拓扑。紧接着,又具体叙述了光伏并网零逆流控制策略的实现方式:先预测逆功率的发生,然后介绍控制零逆流所需要的坐标变换和其变换的原理,以及SVPWM脉冲调制的产生,最后在综合前面一系列分析的基础之上选择使用基于电网电压定向的矢量控制作为零逆流控制策略,使逆变器能紧密跟踪负载功率的变化,锁住大电网的相位,迅速准确地调节逆变器的输出以满足负载的需要。最后,对控制系统的软硬件部分进行具体的设计,其中包括主电路的设计、锁相环的设计和系统程序设计的流程图,并且在MATLAB/Simulink平台上搭建了光伏并网逆变器零逆流控制策略的仿真模型,通过一系列的仿真实验来验证光伏并网零逆流控制策略的有效性。通过仿真波形之间的对比以及对仿真结果的分析可知,本课题所设计的光伏并网零逆流控制策略能够很好地跟踪负载功率变化并能迅速地锁住电网相位,为SVPWM脉冲的生成提供相位基准值,也使得逆变器能够及时地调整输出,使其能恰好满足负载的需要而不至于产生逆流。
[Abstract]:Because there are more high-order harmonics in the photovoltaic power generation system, although there are filtering devices in the large power grid, there are still a small number of harmonics entering the large power grid, which affects the power supply quality and security stability of the large power grid. At present, the application of building photovoltaic is being promoted and spontaneous self-use is advocated. When the electricity generated by photovoltaic system cannot afford the demand of load, it will be supplied by large power grid. But the national standard stipulates, cannot have the electric energy to flow to the large power grid. Therefore, the main research content of this paper is how to control the current to the grid at 0, that is, zero countercurrent control. Firstly, this paper describes the background and significance of the research, lists several traditional control methods of photovoltaic grid-connected inverter and the detection method of inverse power, and analyzes its advantages and disadvantages. It lays a foundation for the introduction of the zero countercurrent control strategy used in this paper. Then the mathematical models of zero countercurrent control system are built in different coordinate systems, and the circuit topology of photovoltaic grid-connected inverter is determined after one-to-one analysis. Then, the realization method of PV grid-connected zero countercurrent control strategy is described in detail: first, the occurrence of inverse power is predicted, then the coordinate transformation required to control zero countercurrent and the principle of its transformation are introduced, as well as the generation of SVPWM pulse modulation. Finally, based on the previous series of analysis, vector control based on grid voltage orientation is chosen as the zero counter current control strategy, so that the inverter can closely track the change of load power and lock the phase of large power grid. Quickly and accurately adjust the output of the inverter to meet the requirements of the load. Finally, the hardware and software of the control system are designed in detail, including the design of the main circuit, the design of phase locked loop and the flow chart of the system program design. The simulation model of PV grid-connected inverter zero countercurrent control strategy is built on the MATLAB/Simulink platform, and a series of simulation experiments are carried out to verify the effectiveness of the PV grid-connected zero countercurrent control strategy. Through the comparison of simulation waveforms and the analysis of simulation results, it can be seen that the PV zero countercurrent control strategy designed in this paper can track the change of load power and quickly lock the phase of power grid. The phase reference value is provided for the generation of SVPWM pulse, which also enables the inverter to adjust the output in time so that it can just meet the requirements of the load without generating countercurrent.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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