三相光伏并网逆变器电网高阻抗谐振抑制方法

针对电网电压高阻抗LCL滤波器谐振问题,提出一种虚拟电阻+电容有源阻尼方法。该方法将虚拟电阻和电容串联之后与三相光伏并网逆变器的滤波电容并联。通过滤波电容电压得到虚拟电阻和电容支路的电流,将虚拟电阻和电容支路的电流作为LCL滤波器谐振抑制有源阻尼电流给定。通过逆变侧电流闭环控制,实现对三相光伏并网逆变器电网高阻抗LCL滤波器谐振抑制。建立15 k W的T型三电平三相光伏逆变器平台,对所提有源阻尼方法进行稳态实验,实验结果验证所提方法的可行性和正确性。

Resonance suppression method of high impedance power grid for three-phase photovoltaic grid-connected inverters

A virtual resistance and capacitor active damping method is proposed due to LCL filter resonance under high impedance power grid condition. Firstly, the virtual resistance and capacitor are connected in series and then connected with filter capacitor of three-phase photovoltaic grid-connected inverters in parallel. The current of virtual resistance and capacitor branch is acquired through the voltage of filter capacitor, to be taken as the active damping current reference for resonance suppression of LCL filter. LCL filter resonance suppression is achieved for three-phase photovoltaic grid-connected inverters under high impedance power grid condition through inverter-side current closed-loop control. The experimental platform of T-type three-level three-phase photovoltaic inverters rated at 15 kW is established. Steady performance of the proposed active damping method is tested, and verified by experimental results to confirm the effectiveness and validity of the proposed method.