摘要
在弱电网中,并网变换器的锁相环会与电流环产生动态交互进而引发小信号(或谐波)失稳问题。为了解决这一问题,利用小信号建模方法建立了并网变换器等效阻抗模型,并在此基础上将变换器阻抗模型与系统稳定性判断方法相结合,利用极点变化轨迹以及Bode图分析了弱电网工况下并网变换器的失稳机理。针对多输入多输出系统,在考虑多环耦合的同时,提出了一种基于数字滤波器的有源阻尼控制策略,3种不同类型的滤波器分别被用于控制系统的稳定性,提高系统稳定裕度。所提出的控制方法能实现锁相环与电流环的之间的解耦,有效抑制多环耦合。同时,给出了控制策略具体的实现方案、参数设计方法,并分析了控制策略对多环耦合部分的影响。另外,为了研究不同工况下所提控制策略的有效性,分析了不同电网强度、锁相环带宽和电流环带宽下采用所提控制策略的系统稳定裕度,并将其与传统控制方法进行了对比。最后,仿真和硬件在环实验结果验证了所提理论的正确性。
In the weak power grid,the dynamic interaction between the phase-locked loop(PLL)and the current loop of the gridconnected converter will lead to small-signal(or harmonic)instability problems.To solve this problem,the small-signal modeling method is used to establish the equivalent impedance model of the grid-connected converter.On this basis,the converter impedance model is combined with the system stability judgment method,and the instability mechanism of the grid-connected inverter in the weak power grid is analyzed by using the pole variation trajectory and the Bode plot.For the multiple-input multipleoutput(MIMO)system,this paper proposes an active damping control strategy based on digital filters while considering multi-loop coupling.Three different types of filters are used to control the system stability and improve the system stability margin.The proposed control strategies can realize the decoupling between the phase-locked loop and the current loop,and effectively restrain the multi-loop coupling.At the same time,this paper also gives the specific implementation scheme of the control strategy and the parameter design method.And the impact of the control strategy on the multi-loop coupling part is analyzed.In addition,in order to study the effectiveness of the proposed control strategy under different conditions,this paper studies the system stability margin using the proposed control strategy under different grid strengths,phase-locked loop bandwidths,and current loop bandwidths.Then,the proposed control strategy is compared with the conventional methods.Finally,the correctness of the proposed theory is verified by the results of the simulation and the hardware-in-the-loop experiment.
作者
刘星琪
邹志翔
姚屹洋
汤建
王政
陈武
LIU Xingqi;ZOU Zhixiang;YAO Yiyang;TANG Jian;WANG Zheng;CHEN Wu(School of Electrical Engineering,Southeast University,Nanjing 210096,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2024年第19期109-119,共11页
Automation of Electric Power Systems
基金
国家自然科学基金资助项目(52377171)。
关键词
跟网型变换器
有源阻尼控制
解耦控制
锁相环
电流环
阻抗建模
稳定性分析
grid-following converter
active damping control
decoupling control
phase-locked loop(PLL)
current loop
impedance modeling
stability analysis
