光伏并网逆变器控制策略及最大功率点跟踪技术研究

发布时间：2018-02-25 07:45

本文关键词： 光伏并网逆变器最大功率点跟踪三电平中点箝位拓扑 PI控制正弦脉宽调制技术　出处：《河北工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：太阳能发电是近年倍受关注的新能源发电形式之一,它既保护了环境又节约了能源。其中光伏并网发电作为最主要的太阳能发电形式,目前有着非常好的发展前景和趋势。在光伏并网发电系统中,并网逆变器是最重要的组成单元,其性能的优劣决定着整个系统多个方面的工作效率。到目前为止,国内外已对光伏并网逆变器进行了大量的研究和应用,但是其中一些关键技术还未得到更好的解决。本课题将针对这些关键技术进行深入的研究。分析了几种传统的光伏最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制算法,并就其共同存在的振荡和误判问题,提出了一种新的MPPT控制算法——基于功率预测的变步长扰动观测法。在PSIM中搭建了光伏MPPT仿真模型,通过对比新型MPPT控制算法与传统控制算法的跟踪效果来进行理论验证。并网逆变器作为光伏并网系统中最重要的组成单元,其拓扑结构和控制策略的选择也是至关重要的。本课题选用输出波形正弦度高的三电平中点箝位(简称NPC三电平)逆变器拓扑结构和恒功率控制(PQ)策略,并详细分析了它们的工作原理。然后基于NPC三电平拓扑结构建立不同坐标系下的三相逆变器数学模型,并采用比例积分控制(PI)和正弦脉宽调制(SPWM)技术相结合的控制方法来实现逆变器的控制。最后,在PSIM中建立了三相光伏并网逆变器仿真模型,通过合理设置实验参数进行逆变器拓扑结构和控制策略的仿真,实验结果证明本课题选用的光伏并网逆变器拓扑结构和控制策略的正确性和有效性。
[Abstract]:Solar power generation is one of the new forms of energy generation, which not only protects the environment but also saves energy, among which grid-connected photovoltaic power generation is the most important form of solar power generation. In photovoltaic grid-connected generation system, grid-connected inverter is the most important component unit, and its performance determines the efficiency of the whole system in many aspects. Photovoltaic grid-connected inverters have been studied and applied extensively at home and abroad. However, some of the key technologies have not been solved better. In this paper, we will study these key technologies and analyze several traditional maximum Power Point tracking (MPPT) control algorithms. A new MPPT control algorithm, variable step size perturbation observation method based on power prediction, is proposed to solve the common oscillation and misjudgment problems. A photovoltaic MPPT simulation model is built in PSIM. By comparing the tracking effect of the new MPPT control algorithm with the traditional control algorithm, the grid-connected inverter is regarded as the most important unit in the photovoltaic grid-connected system. The choice of topology and control strategy is also very important. In this paper, we choose the three-level neutral point clamp (NPC) inverter topology with high sinusoidal output waveform and the constant power control strategy. Then based on the three-level topology of NPC, the mathematical model of three-phase inverter in different coordinate system is established. The proportional integral control (Pi) and sinusoidal pulse width modulation (SPWM) technology are used to control the inverter. Finally, the simulation model of three-phase photovoltaic grid-connected inverter is established in PSIM. The topology structure and control strategy of the inverter are simulated by setting the experimental parameters reasonably. The experimental results show that the topology structure and control strategy of the photovoltaic grid-connected inverter selected in this paper are correct and effective.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM615;TM464

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