光伏并网多逆变器并联建模及谐振分析

Modeling and Resonance Analysis of Multi-paralleled Grid-tied Inverters in PV Systems

针对光伏并网发电系统中多逆变器并联谐振问题,首先,建立包括电流控制、电压前馈和脉宽调制(pulse width modulation,PWM)谐波特性的单台逆变器小信号电路模型,并扩展成多逆变器并联小信号模型,提出基于2台逆变器和同类激励源合并的多逆变器并联系统小信号模型简化等效方法,分析多逆变器的基本谐振特性,并得出谐振与各逆变器控制和载波同步性有关的结论。最后,通过相关的实验研究,验证了所提出的多逆变器简化等效模型和理论分析的正确性。

For the resonance problem of multi-paralleled grid-tired inverters in PV systems, Firstly, a small-signal circuit model of single inverter including current control, voltage feed-forward and PWM harmonic characteristics is established, and is expanded into a small-signal model for multi-paralleled inverters. An equivalent method of two inverters and a simplified method of a similar excitation source are proposed. And then, on this basis, the basic resonance characteristics of multi-paralleled inverters are analyzed, and the conclusion of that resonance of multi-paralleled inverters is related to the synchronism of control and carrier wave. Finally, the proposed equivalent model and analysis of resonance characteristics are verified by experiments.