基于LC滤波器多机并网谐振影响及对策研究

Research on Resonance Influence of Multi-Inverter Connecting Grid and Countermeasures

在逆变器多机并网的背景下,研究分析了基于LC滤波器在弱电网条件下并网点电压谐振的机理和谐振频率的变化原因,得出了弱电网下多机并网会使电网越来越弱的结论。分析了谐振对并网逆变器设计和控制带来的影响及对策,提出一种新的基于虚拟阻尼介入的并网逆变器控制模型,研究了反馈系数对减弱谐振的影响,通过仿真试验,证明了新的控制模型能够适应弱电网,削弱并网点电压和电流的谐振,并能改善并网环境。

Under the background of multi-inverter connecting into grid, the mechanism of the connected point voltage resonance and transformation of the resonance frequency were analyzed. That gives support of the conclusion that the gird will be ＂weaker＂ with the multi-inverter connecting. Then the influence of the resonance to the design and control of the inverter were summarized. This paper proposed a new method of injecting damping into the control model. The simulation results demonstrate that this new method can adapt with the weak grid, weaken the resonance of the connected point voltage and the injecting current, and improve the grid-connected environment.