并网变流器频率耦合振荡分析及解耦控制设计  

Frequency Coupling Oscillation Analysis and Decoupling Control Design of Grid Connected Converter

作　　者：唐欣[1] 李珍 李勇 何洋 TANG Xin;LI Zhen;LI Yong;HE Yang(School of Electrical&Information Engineering,Changsha University of Science&Technology,Changsha 410114,Hunan Province,China)

机构地区：[1]长沙理工大学电气与信息工程学院,湖南省长沙市410114

出　　处：《中国电机工程学报》2023年第8期3127-3136,共10页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51977013)。

摘　　要：阻抗法常用于风电和太阳能并网系统的稳定性分析,变流器控制结构或参数的不对称可能引发频率耦合振荡现象,从而导致基于序阻抗的稳定性分析出现偏差。为此,文中首先建立变流器dq导纳模型,并将其控制结构分解为两个子系统分析耦合产生的原因;然后通过在变流器的电流内环和功率外环中加入解耦因子,分别消除由锁相环(phase locked loop,PLL)控制结构和功率外环控制参数不对称造成的频率耦合,使得变流器序导纳矩阵中的反对角元素为0。由于电网的序阻抗矩阵中反对角元素也为0,故并网变流器系统可以看作单输入单输出(single input single output,SISO)系统,进而能够运用传统的奈奎斯特判据分析其稳定性。解耦后的系统不存在频率耦合振荡现象,无需应用广义奈奎斯特判稳,便于分析系统振荡机理和谐振问题,分析结果可用于指导变流器控制器设计、电网规划及运行。仿真和实验都验证了所提全频带解耦方法的可行性和有效性。Impedance method is often used to analyze the stability of grid-connected system such as wind energy and solar energy.The asymmetry of converter control structure or parameters will lead to frequency coupling oscillation in grid-connected converter system,which causes deviations in the stability analysis based on sequence impedance.Thus,this paper first established the dq-domain admittance model of the converter,and decomposed its control structure into two subsystems to analyze the causes of coupling.Then,the influence of frequency coupling caused by asymmetric phase-locked loop(PLL)control structure and outer power loop control parameters was eliminated by adding decoupling factors to the inner current control loop and outer power control loop of the converter,so that the off-diagonal elements in the converter sequence admittance matrix were 0.Because the off-diagonal elements in the sequence impedance matrix of the grid were also 0,the grid-connected converter system can be regarded as a single-input and single-output(SISO)system and the stability can be analyzed by using the traditional Nyquist criterion.Moreover,there was no frequency coupling oscillation in the decoupled system,so it is not necessary to apply generalized Nyquist to judge stability,which was convenient for analyzing system oscillation mechanism and resonance problems.The analysis results can be used to guide converter controller design,power grid planning and operation.Finally,simulation and experiments verified the feasibility and effectiveness of the proposed decoupling method.

关 键 词：阻抗建模 并网系统 稳定性分析 频率耦合振荡 单输入单输出 

分 类 号：TM46[电气工程—电器]