平均值模型的有效性研究及其应用

发布时间：2018-12-12 13:36

【摘要】：随着现代电力的不断发展,环境污染状况日益加剧,可再生能源逐渐成为各国能源发展的主要目标。微电网和柔性直流电网作为接纳分布式可再生能源和大规模集中式可再生能源的有效手段,逐渐成为研究的热点。微电网需要大量的可控的电力电子装置进行变流处理,同时柔性直流电网中模块化多电平换流器也含有数量众多的子模块。这导致在对微电网和柔性直流电网进行详细模型仿真时,内存需求大,仿真速度慢,仿真时间长。针对含有大规模电力电子装置的微电网和模块化多电平换流器的柔性直流输电系统,论文深入开展了平均值建模方法的有效性评估和应用研究,主要工作如下:(1)系统分析了平均值建模理论。首先分析了平均值建模方法的基本原理,在此基础上,对平均值建模的两种方法——状态空间平均法和开关周期平均法进行了详细的理论推导,为微电网和柔性直流输电系统平均值模型的建立奠定了基础。(2)研究了含典型电力电子装置的微电网快速仿真。首先,根据平均值建模方法,建立了微网中典型电力电子装置(DC/DC、DC/AC、AC/DC变换器)的平均值模型,并验证了它们的有效性;其次,建立了微电网中两种典型分布式电源——光伏发电和微型燃汽轮机的模型;再次,将平均值建模方法应用于微电网的快速仿真,建立了含典型电力电子装置的微电网的平均值模型;最后,在MATLAB中搭建了微电网的详细模型和平均值模型,通过对比仿真结果,验证了平均值建模方法的精度和快速性。(3)研究了基于模块化多电平换流器柔性直流输电系统的快速仿真。首先,分析了MMC详细模型的工作原理、调制方式,以及MMC子模块的拓扑结构和工作方式;其次,根据平均值建模方法,建立了 MMC的平均值模型和基于MMC的柔性直流输电系统的平均值模型,最后,在PSCAD中搭建了 41电平MMC柔性直流输电系统的详细模型与平均值模型,通过对比分析在稳态运行和暂态故障下平均值模型和详细模型的仿真结果,验证了 MMC平均值模型在仿真精度和计算效率方面的有效性。论文的研究结果表明,平均值模型能够在合理的精度范围内正确反映被建模对象的外部特征,而且大大提高了仿真速度。这对于通过电磁暂态仿真进一步研究含有大规模电力电子装置的微电网和柔性直流电网的运行特性和协调控制策略,具有重要的理论意义和应用价值。
[Abstract]:With the continuous development of modern electric power, environmental pollution is becoming more and more serious. Renewable energy has gradually become the main goal of energy development in various countries. Microgrid and flexible DC network, as an effective means to accept distributed renewable energy and large-scale centralized renewable energy, have gradually become the focus of research. The microgrid needs a large number of controllable power electronic devices to process the converter, and the modularized multilevel converter also contains a large number of sub-modules in the flexible DC network. This results in a large memory requirement, slow simulation speed and long simulation time in the detailed simulation of microgrid and flexible DC network. Aiming at the flexible direct current transmission systems with large-scale power electronic devices and modularized multilevel converters, the effectiveness evaluation and application research of the average modeling method are carried out in this paper. The main work is as follows: (1) the mean value modeling theory is analyzed systematically. Firstly, the basic principle of the mean value modeling method is analyzed. On the basis of this, two methods of mean value modeling, state space average method and switching cycle average method, are derived in detail. It lays a foundation for the establishment of average value model of microgrid and flexible direct current transmission system. (2) Fast simulation of microgrid with typical power electronic devices is studied. Firstly, according to the average value modeling method, the average value model of typical power electronic devices (DC/DC,DC/AC,AC/DC) in microgrid is established, and their validity is verified. Secondly, the models of two typical distributed generators in microgrid, photovoltaic generation and micro turbine, are established. Thirdly, the average value modeling method is applied to the rapid simulation of microgrid, and the average value model of microgrid with typical power electronic devices is established. Finally, the detailed model and average model of microgrid are built in MATLAB, and the simulation results are compared. The accuracy and rapidity of the mean value modeling method are verified. (3) the fast simulation of flexible HVDC transmission system based on modularized multilevel converter is studied. Firstly, the working principle, modulation mode, topological structure and working mode of MMC submodule are analyzed. Secondly, according to the average value modeling method, the average value model of MMC and the average value model of flexible direct current transmission system based on MMC are established. Finally, the detailed model and average model of 41 level MMC flexible direct current transmission system are built in PSCAD. The simulation results of average value model and detailed model under steady-state operation and transient fault are compared to verify the effectiveness of MMC average model in simulation accuracy and computational efficiency. The research results show that the mean value model can accurately reflect the external characteristics of the modeled object within a reasonable precision range and greatly improve the simulation speed. It is of great theoretical significance and practical value to further study the operation characteristics and coordinated control strategy of microgrid and flexible DC network with large-scale power electronic devices through electromagnetic transient simulation.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM743

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