微网逆变器并网与离网切换控制研究

发布时间：2018-04-01 19:02

本文选题：PQ控制　切入点：改进下垂控制　出处：《安徽理工大学》2017年硕士论文

【摘要】：全球经济迅速发展,导致传统化石能源日益枯竭。开拓新能源是发展的必然之路。目前而言,传统能源在能源的利用中依旧占很大的比重。随着世界各国发展的深入,环境污染和全球变暖的问题日益突出,严重影响了人类的生存质量。为解决发展与生存质量的矛盾,人类必然要放眼于可再生且清洁的新能源。分布式发电系统的研究与实施在许多国家已经开展起来,相应的微网技术的研究成为了热点。世界各国针对其对微网的定义和研究情况,分析了微网价值所在。微网可以当作分布式发电系统与电网之间的媒介,微网技术有效地解决二者之间的矛盾,提高了能源的利用效率、减少了不可再生能源带来的环境污染。微网运行过程中,独立和并网两种模式之间的切换充分发挥了分布式发电的优越性,为负载提供不间断能量供应。论文介绍了微网逆变器并网、离网稳态运行模式的控制策略,并网采用PQ控制,独立运行采用下垂控制。无论微网系统工作在并网还是离网,其系统内的负载电压与电网电压在相位和数值大小上都很难完全相同。所以在并网开关动作之前,必须使二者电压相位及大小同步。电网检修或故障时,逆变器切到下垂控制,瞬间断开并网开关,微网进入独立运行模式;电能剩余或者电网恢复正常工作时,逆变器切换到PQ控制,瞬间合上并网开关,微网进入并网模式。这就是微网的模式切换。切换过程中,由于微源种类多、切换时间不一等因素会造成电压电流冲击,本文提出一种基于虚拟阻抗的改进下垂控制,使得两种模式顺利切换,很好地完成功率合理分配。论文分别在Matlab/simulink中搭建了并网、离网逆变器模型,对两种稳态运行模式进行了研究。综合前两种模型,完成模式切换的仿真,结果表明,两种模式之间切换可以顺利进行。
[Abstract]:The rapid development of the global economy has led to the depletion of traditional fossil energy. The development of new energy is the inevitable way of development. At present, traditional energy still accounts for a large proportion in the utilization of energy. With the development of various countries in the world, The problems of environmental pollution and global warming have become increasingly prominent, which have seriously affected the quality of life of human beings. In order to solve the contradiction between development and quality of life, Human beings must focus on renewable and clean new energy sources. The research and implementation of distributed power generation systems have been carried out in many countries. According to the definition and research situation of microgrid, the value of microgrid is analyzed. Microgrid can be used as a medium between distributed generation system and power grid. Microgrid technology can effectively solve the contradiction between the two, improve the efficiency of energy utilization and reduce the environmental pollution caused by non-renewable energy. The switching between independent and grid-connected modes gives full play to the advantages of distributed generation and provides uninterrupted energy supply for the load. This paper introduces the control strategy of grid-connected micro-grid inverter and off-grid steady-state operation mode. PQ control is adopted in grid-connected mode. Droop control is used for independent operation. Whether the microgrid system works in grid-connected or off-grid mode, the load voltage in the system is difficult to be identical with the voltage in the power grid in terms of phase and numerical value, so before the grid-connected switch action, the load voltage in the microgrid system is difficult to be exactly the same as that in the grid voltage. It is necessary to synchronize the voltage phase and the size of the two voltages. When the power grid is overhauled or malfunction, the inverter cuts to the droop control, disconnects the grid-connected switch instantly, and the microgrid enters the independent operation mode; when the power surplus or the power grid returns to normal operation, The inverter switches to PQ control, closes the grid-connected switch instantly, and the microgrid enters grid-connected mode. This is the mode switching of the microgrid. In this paper, an improved droop control based on virtual impedance is proposed, which makes the two modes switch smoothly, and completes the reasonable allocation of power. In this paper, the grid-connected and off-grid inverter models are built in Matlab/simulink, respectively. The simulation of mode switching is completed by synthesizing the first two models. The results show that the switching between the two modes can be carried out smoothly.
【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;TM727

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