在高渗透率电网环境下,多逆变器并网系统更易出现谐波放大甚至失稳的问题。众多学者致力于通过并联阻抗适配器来缓解这个问题,但其既不易实现过小阻抗的虚拟,也无法有效抑制电网背景噪声的放大。针对上述问题,提出统一阻抗适配器,弥补并联阻抗适配器的不足。首先基于阻抗模型对弱网下多逆变器电网络耦合系统的谐波放大机理进行分析,明确了系统谐波放大甚至失稳的原因——系统欠阻尼特征和谐波源。其次介绍了并联阻抗适配器解决上述问题的机理与不足之处。再次,提出一种在并网点虚拟谐波段串并联阻抗相结合的统一阻抗适配器,解决系统谐波放大问题,提高并网电流的质量。最后搭建RT-LAB硬件在环仿真实验平台,验证了所提方案的有效性。
Abstract
In the high permeability grid environment, the multi-inverter grid-connected system is more prone to harmonic amplification or even instability. Many scholars are committed to alleviating this problem by parallel active damper, but it is not easy to realize the virtual of small impedance and can not effectively suppress the amplification of grid background noise. In view of the above shortcomings, a unified active damper is proposed to make up for the shortcomings of the parallel active damper. Firstly, based on the impedance model, the harmonic amplification mechanism of the electrical network coupling system of multi-inverter under weak network is analyzed, and the reasons of the harmonic amplification and even instability of the system, the harmonic source of the system and underdamping characteristics is clarified. Secondly, the mechanism and shortcomings of parallel impedance damper to solve the above problems are introduced. Thirdly, a unified active damper combining series-parallel impedance in the virtual harmonic segment of the grid-connected point is proposed to solve the problem of harmonic amplification of the system and to improve the quality of the grid-connected current. Finally, RT-LAB HIL simulation platform is built to verify the effectiveness of the proposed scheme.
关键词
逆变器 /
谐波分析 /
硬件在环 /
阻抗适配器
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参考文献
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基金
国家自然科学基金（52177175; 51937003）; 高等学校学科创新引智计划资助（BP0719039）
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