并网变换器的多频率耦合等幅振荡分析  

Analysis of Sustained Multi-frequency Oscillations in Grid-connected VSC

作　　者：王玉芝 王亮[2] 姜齐荣[1] WANG Yuzhi;WANG Liang;JIANG Qirong(Department of Electrical Engineering,Tsinghua University,Haidian District,Beijing 100084,China;School of Automation,Beijing Institute of Technology,Haidian District,Beijing 100081,China)

机构地区：[1]清华大学电机工程与应用电子技术系,北京市海淀区100084 [2]北京理工大学自动化学院,北京市海淀区100081

出　　处：《电网技术》2023年第3期950-958,共9页Power System Technology

基　　金：国家自然科学基金智能电网联合基金集成项目(U1866601)。

摘　　要：电压源型并网变换器与交流电网相互作用会引发新型电磁振荡现象。受控制器非线性环节的影响,该振荡不能持续发散,最终将形成等幅振荡。目前,已有研究多利用描述函数法对系统的限幅环节进行建模,从而计算振荡的幅值和频率。但是这些模型都忽略了非线性环节导致的高阶振荡分量。对现有方法进行了改进,提出了一种计及高阶振荡分量的并网变换器等幅振荡分析方法,推导了考虑高阶振荡分量后非对称限幅的描述函数,及考虑高阶分量后等幅振荡频率和幅值的计算方法,并将该方法应用于单轴限幅和双轴限幅的振荡分析。最后,利用仿真验证了所提改进方法的准确性。理论分析和仿真验证表明,所提方法提高了并网变换器等幅振荡的分析精度,并且能够计算高阶振荡分量的幅值。The interaction between grid-connected voltage source converter and the AC grid may lead to electromagnetic oscillations. Due to the influence of the non-linearity of controller, the oscillation cannot diverge continuously and eventually a sustained oscillation appears. Many existing researches use the describing function to model the limiter of the converter to calculate the amplitude and frequency of the sustained oscillation. However, the influence of high-order oscillation components caused by the non-linearity on the oscillation is ignored. In this paper, the existing method is improved and a method considering high-order oscillation components is proposed. The describing function of asymmetric limit considering the high-order oscillation component is derived. The amplitude and frequency characteristics of sustained oscillation considering the high-order oscillation components are analyzed. This method is adopted in the analysis of oscillations considering both single-axis and dual-axis limitations. Finally, the proposed method is verified by simulations in the PSCAD/EMTDC. Theoretical analysis and simulation results show that the proposed analysis method improves the analysis accuracy of sustained oscillations of the grid connected converter, and quantitatively calculate the amplitude of high-order oscillation component.

关 键 词：电压源型并网变换器 限幅环节 等幅振荡 高阶振荡分量 描述函数 

分 类 号：TM721[电气工程—电力系统及自动化]