基于复转矩系数的无内环构网变流器低频振荡分析与抑制策略  

Complex Torque Coefficient Based Analysis and Suppression Strategy of Low-frequency Oscillation in Grid-forming Converter Without Inner-loop

作　　者：陈雪韬 吴超 王简 王勇[1] 黄晓芸 刘毅斌 CHEN Xuetao;WU Chao;WANG Jian;WANG Yong;HUANG Xiaoyun;LIU Yibin(School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Guangxi Electric Power Design Institute Co.,Ltd.,China Energy Engineering Group,Nanning 530007,China)

机构地区：[1]上海交通大学电子信息与电气工程学院,上海市200240 [2]中国能源建设集团广西电力设计研究院有限公司,广西壮族自治区南宁市530007

出　　处：《电力系统自动化》2025年第2期41-52,共12页Automation of Electric Power Systems

基　　金：国家自然科学基金资助项目(52207063)。

摘　　要：在电力电子化程度逐渐增加的电力系统中,构网变流器由于能够自主建立机端电压和频率的特性被广泛研究。其中,无内环的构网变流器因其电压源特性较好、控制结构简单而应用较广。然而,无内环变流器在面临系统阻尼较弱情形时容易进入低频振荡。为提高无内环变流器的并网低频稳定性,文中利用复转矩系数分析方法,揭示了无内环构网变流器的低频失稳机理为常值虚拟阻抗在低频区间无滞后特性,故而难以提供系统低频阻尼转矩,且虚拟阻抗增加会引起无功环路的负阻尼增大。针对常值虚拟阻抗策略在面临扰动时所提供低频阻尼转矩不足的问题,提出基于低通滤波器的虚拟阻抗策略以增加阻尼转矩进而抑制低频振荡。最后,通过MATLAB/Simulink仿真以及StarSim半实物实验验证了所提低通虚拟阻抗策略的有效性。In the power system where the power electronization level is progressively increasing,grid-forming converters are extensively studied due to their capability of autonomously establishing the terminal voltage and the frequency.Among them,the grid-forming converter without the inner-loop is widely used for its strong voltage source characteristics and simple control structure.However,this converter is prone to low-frequency oscillation when the system damping is weak.To enhance the lowfrequency stability of the grid-connected converter without the inner-loop,this paper employs a complex torque coefficient analysis method to reveal that the low-frequency instability mechanism of the grid-forming converter without the inner-loop lies in the lack of lag characteristics of the constant virtual impedance in the low-frequency range,thus making it difficult to provide low-frequency damping torque to the system.Moreover,the increase in the virtual impedance can lead to an increase in the negative damping in the reactive power loop.Therefore,in response to the insufficient low-frequency damping torque provided by constant virtual impedance strategies when facing disturbances,this paper proposes a virtual impedance strategy based on low-pass filters to increase the damping torque and suppress low-frequency oscillations.Finally,the effectiveness of the proposed low-pass virtual impedance strategy is validated through the MATLAB/Simulink simulation and the StarSim semi-physical experiment.

关 键 词：构网变流器 低频振荡 复转矩系数 阻尼 虚拟阻抗 

分 类 号：TM712[电气工程—电力系统及自动化] TM46