摘要
数字控制LCL型并网逆变器的固有控制延时会影响原有谐振阻尼方案的控制特性,从而降低并网逆变器在弱电网下的鲁棒性。该文首先基于不同参数建立多机并联系统在弱电网下的多输入多输出矩阵,并推出了确保系统进网电流稳定性以及各模块交互电流稳定性的三条判据。进一步地,基于频域阻抗法分析数字控制延时在模块采用不同开关频率的情况下对系统鲁棒性的影响,进而发现在系统中引入高带宽逆变器对于抑制低频谐振的有效性。然后,分析了高频模块与低频模块之间的交互稳定性,据此选取高带宽并网逆变器的开关频率。最后,在实验室搭建了一台基于新型宽禁带器件GaN的高带宽并网逆变器原理样机,并将其并入低频模块并网系统中,通过实验验证了所提出的高带宽并网逆变器有助于提高弱电网下系统的鲁棒性,从而为提高分布式发电系统的稳定性提供了新思路。
The inherent control delay of the digital-control LCL grid-connected inverter would affect the control characteristic of the original resonance damping scheme,thereby decreasing the robustness of the system in weak grid.The multiple-input-multiple-output(MIMO)matrix of the multi-inverter parallel system based on different parameters is established firstly,and three criteria to ensure the stability of the system's grid current and interactive current is put forward.Furthermore,the influence of the digitalcontrol-delay on the robustness of the system when the module adopts different switching frequencies is analyzed based on the frequency domain impedance method.Therefore,the introduction of a highbandwidth inverter in the multi-inverter system is found to be effective in suppressing low-frequency resonance.Next,the interaction stability between the high-frequency module and the low-frequency module is analyzed,and the switching frequency of the high-bandwidth inverter is selected.Finally,a prototype of the high-bandwidth grid-connected inverter based on GaN was built.The effectiveness of the high-bandwidth inverter to improve the robustness of the system in weak grid is verified by experiment.This scheme provides a new idea for improving the stability of the distributed generation system.
作者
沈姝衡
方天治
章益凡
Shen Shuheng;Fang Tianzhi;Zhang Yifan(College of Automation Engineering Nanjing University of Aeronautics and Astronautics,Nanjing 211106 China)
出处
《电工技术学报》
EI
CSCD
北大核心
2022年第21期5548-5561,共14页
Transactions of China Electrotechnical Society
基金
国家自然科学基金(52077102)
江苏省自然科学基金(BK20201299)资助项目。
关键词
多并网逆变器并联系统
鲁棒性
高带宽
GAN器件
Multiple-grid-connected-inverter parallel system
robustness
high-bandwidth
GaN device
