摘要
长距离输电缆(LTC)与并网逆变器交互作用易引发系统谐波不稳定的风险,且忽略线路频变特性可能会导致稳定性误判。文中计及输电线路的分布参数特性和频变特性,研究如何评估这类逆变器并网系统的稳定性。首先,基于矢量匹配法对含LTC的交流系统进行等值,同时考虑逆变器的内外环控制、锁相环、控制延时等环节,建立dq旋转坐标系下逆变器并网系统高频状态空间模型;其次,采用参与因子分析方法辨识出导致谐波不稳定的关键影响环节,并基于根轨迹方法分析了LTC频变特性、延迟时间、控制器参数、电缆长度和电网阻抗对系统稳定性的影响;再次,提出了基于参数灵敏度分析和矩阵相似变换的系统稳定性改善方法,并对改进后系统的谐波稳定性进行分析;最后,基于RT-LAB构建硬件在环实验平台进行了验证,实验结果验证了理论分析的正确性。
The interaction between the long transmission cable(LTC)and the grid-connected inverter can easily cause the risk of harmonic instability of the system.Ignoring the frequency-dependent characteristics of the line may lead to stability misjudgment.In order to evaluate the stability of the grid-connected inverter system,the distribution parameter characteristics and frequencydependent characteristics of LTCs are taken into account in this paper.Firstly,the equivalence of the AC system is carried out based on the vector fitting method,and the high-frequency state-space model of the grid-connected inverter system in the dq coordinate system is established with consideration of the inner and outer loop control,phase-locked loop and control delay.Secondly,the key influencing links leading to the harmonic instability are identified by using the participation factor analysis method.Meanwhile,the influences of the frequency-dependent characteristics of LTCs,delay time,controller parameters,cable length,and power grid impedance on the system harmonic stability are analyzed by using the root locus method.Thirdly,a method for improving the system stability is proposed based on the parametric sensitivity analysis and the matrix similarity transformation,and the harmonic stability of the improved system is analyzed.Finally,the verification is carried out on the RT-LAB based hardware-in-loop experimental platform,and the experimental results verify the correctness of theoretical analysis.
作者
解润生
张国荣
解宝
XIE Runsheng;ZHANG Guorong;XIE Bao(School of Electrical Engineering and Automation,Hefei University of Technology,Hefei 230009,China;Research Center for Photovoltaic System Engineering of Ministry of Education(Hefei University of Technology),Hefei 230009,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2024年第2期128-139,共12页
Automation of Electric Power Systems
基金
国家重点研发计划资助项目(2017YFB0903100)
国家电网公司科技项目(521104170043)。
关键词
逆变器并网系统
长距离输电缆
谐波不稳定
状态空间模型
根轨迹
灵敏度分析
grid-connected inverter system
long transmission cable
harmonic instability
state-space model
root locus
sensitivity analysis
