含励磁特性的虚拟同步发电机建模与控制策略研究

发布时间：2019-03-26 09:48

【摘要】：由于环境污染以及能源危机问题的日益加重,基于清洁可再生能源的分布式发电技术得到了快速发展,为了能够更好的消纳分布式电源的出力以及稳定电网的正常运行,微网技术得到了不断的发展。微电网中的微源大多是通过电力电子逆变器实现与大电网的并联运行,在受到扰动或故障情况下,对于基于逆变器接口的分布式电源而言,其动态响应速度快,几乎没有惯性,无法像传统同步发电机一样利用旋转部件的旋转惯性来抑制功率或频率的波动,在孤岛运行时难以为电网提供电压及频率支撑作用。同时,对于冗余配置的并联逆变器机组间,由于电路参数或者开关元件动作不完全一致等因素,将会在并联机组之间出现环流,对于环流抑制问题也有待解决。基于以上问题,本文的主要研究内容如下:首先,对虚拟同步发电机进行了拓扑分析,将三阶同步发电机模型的电气方程以及转子运动方程引入到逆变器的控制策略中,建立了虚拟同步发电机模型,并引入了虚拟惯性、虚拟阻尼参数,通过仿真分析,得出了阻尼及惯性两个虚拟参数对于系统运行稳定性的影响。其次,基于传统同步发电机的运行特性分析,设计了虚拟同步发电机并网运行时的频率控制策略及电压控制策略,实现了单台虚拟同步发电机的调频以及调压功能。在电压控制中,总结了现有的基于无功-电压下垂特性所设计的电压控制策略,同时考虑同步发电机励磁特性,提出一种基于虚拟励磁控制系统的电压控制策略,最后通过仿真验证了所设计的控制策略的控制性能。最后,分析了虚拟同步发电机双机并联运行时环流的产生机理及环流的物理含义,设计了电压差值反馈的双机环流抑制策略,并对两种电压控制策略下的并联系统进行环流抑制仿真实验,验证了所设计的环流抑制策略的有效性。
[Abstract]:Due to the increasing environmental pollution and energy crisis, distributed power generation technology based on clean and renewable energy has been developed rapidly. In order to better absorb the output of distributed power and stabilize the normal operation of the power grid, Microgrid technology has been continuously developed. Most of the micro sources in microgrid are operated in parallel with large power grid through power electronic inverter. In the case of disturbance or fault, the dynamic response speed of distributed power supply based on inverter interface is fast and there is almost no inertia. The rotating inertia of rotating parts can not be used to restrain the fluctuation of power or frequency like the traditional synchronous generator, and it is difficult to provide voltage and frequency support for the grid when the island is running. At the same time, for redundant parallel inverter units, due to the circuit parameters or switching elements are not completely consistent, there will be circulation between parallel units, and the problem of circulation suppression needs to be solved. Based on the above problems, the main research contents of this paper are as follows: firstly, the topology analysis of the virtual synchronous generator is carried out, and the electrical equation of the third-order synchronous generator model and the rotor motion equation are introduced into the control strategy of the inverter. The virtual synchronous generator model is established, and the virtual inertia and virtual damping parameters are introduced. Through the simulation analysis, the influence of the two virtual parameters, damping and inertia, on the stability of the system is obtained. Secondly, based on the analysis of the operation characteristics of the traditional synchronous generator, the frequency control strategy and voltage control strategy of the virtual synchronous generator when connected to the grid are designed, and the frequency modulation and voltage regulation functions of the single virtual synchronous generator are realized. In voltage control, the existing voltage control strategies based on reactive power-voltage droop characteristics are summarized. Considering the excitation characteristics of synchronous generators, a voltage control strategy based on virtual excitation control system is proposed. Finally, the control performance of the designed control strategy is verified by simulation. Finally, the mechanism of circulation and the physical meaning of circulation in parallel operation of virtual synchronous generator are analyzed, and the suppression strategy of dual-machine circulation based on voltage difference feedback is designed. Simulation experiments are carried out for the parallel systems under two voltage control strategies to verify the effectiveness of the designed loop suppression strategy.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM31

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