具有同步发电机接口特性的微网逆变器并联控制策略研究

发布时间：2018-05-18 05:29

本文选题：微电网 + 虚拟同步发电机　；参考：《西安理工大学》2017年硕士论文

【摘要】：微网以能源供给绿色多样、节能低碳、适应不同用户的多种电力需求为目标,是传统电网向未来智能电网过渡的时代产物。为提高微网自治可靠性及新能源大规模入网的网侧接纳能力,国内外学者提出了虚拟同步发电机(Virtual Synchronous Generator,SVG)技术,阻尼和惯性的加入可使快速灵敏的电力电子变换器模拟同步发电机外特性。本文主要针对单台VSG离/并网和两台VSG并联组网多模式下控制策略进行研究改进,总结为以下几个方面。首先,介绍了课题研究背景,微网变换器并联运行的几种典型控制策略及虚拟同步发电机国内外研究现状。其次,介绍了虚拟同步发电机基本原理,并经过小信号建模及对VSG单机孤岛及并网模式下运行特性的分析,得出各参数对系统稳定性和功频响应的影响机理。先后提出改进自适应调节控制以及恒压恒频控制方法,保证单机带载可靠运行;基于虚拟冲击电流的预同步方法,在并网前完成对电网相位的追踪,大大降低并网瞬间的电流冲击;以及加入微分负反馈环节的惯性电压下垂控制策略,平抑电压波动也可减缓无功-电压的跌落过程;仿真和实验验证了所提控制策略的正确性。再次,对VSG多机并联模式下的运行特性进行了分析,通过建立并联数学模型得到交流母线电压、VSG输出电流与负载、VSG端电压之间的关系,通过双机并联模型分析微源间环流的产生机理,根据功率控制框图推导各VSG输出功率表达式,为之后提高功率分配精度和抑制环流提供理论依据。最后,针对线路阻抗对无功功率分配的影响提出一种改进励磁环控制策略,建立小信号模型得出改进算法中各参数对微网稳定运行的影响;分析改进型控制策略下VSG并联组网的运行特性,并针对VSG并机及加减载时带来的环流、功率振荡问题,提供基于阻抗匹配原则的参数设计方法,该参数优化方案可提高VSG动态性能,抑制环流、平抑功率振荡,仿真和实验验证了所提控制策略和参数选取方案的正确性。
[Abstract]:In order to improve the reliability of the micro network and the network side acceptance of the new energy large-scale network, the domestic and foreign scholars have proposed a virtual synchronous generator (Virtual Synchronous). Generator, SVG) technology, damping and inertia can make the fast and sensitive power electronic converter simulate the external characteristics of synchronous generator. This paper mainly focuses on the research and improvement of the control strategy of the single VSG off / grid and two VSG parallel networks, and summarizes the following aspects. Firstly, the research background and the microgrid transformation are introduced. Several typical control strategies in parallel operation and the research status of virtual synchronous generator at home and abroad. Secondly, the basic principle of virtual synchronous generator is introduced. Through the modeling of small signal and the analysis of the running characteristics of VSG single island and grid connected mode, the influence mechanism of each parameter on the stability of the system and the response of the power frequency is obtained. The adaptive control control and constant voltage and constant frequency control methods are improved to ensure the reliable operation of the single machine with load. The pre synchronization method based on the virtual impact current completes the tracking of the phase of the power grid before the grid connection, greatly reduces the current impact in the grid connection, and the inertia voltage droop control strategy with the differential negative feedback loop, and suppress the voltage wave. The motion can also slow down the falling process of reactive power voltage; simulation and experiment verify the correctness of the proposed control strategy. Again, the operation characteristics of the VSG multi machine parallel mode are analyzed. The relationship between the AC bus voltage, the VSG output current and the load, the VSG terminal voltage is obtained by establishing the parallel mathematical model, and the parallel model is divided into two parallel parallel models. This paper analyses the mechanism of the circulation between the micro sources, derives the expression of the output power of each VSG according to the power control block diagram, and provides a theoretical basis for improving the power distribution precision and suppressing the circulation. Finally, an improved excitation loop control strategy is proposed for the effect of line impedance on the reactive power distribution, and a small signal model is established to obtain each improved algorithm. The influence of parameters on the stable operation of micro network; analysis of the operating characteristics of VSG parallel networking under the improved control strategy, and to provide a parameter design method based on the impedance matching principle for the circulation and power oscillation caused by VSG and the machine and the loading and subtraction. The parameter optimization scheme can improve the dynamic performance of the VSG, suppress the circulation, suppress the power oscillation and imitate. The correctness of the proposed control strategy and parameter selection scheme is verified by experiments and experiments.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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