一种基于LLCL型滤波器的光伏逆变器分析与设计

Study on a Novel LLCL Output-filer of Photovoltaic Gird-connected Inverter

提出了新型并网逆变器的高阶功率滤波器的拓扑电路,称为LLCL滤波器。采用新型LLCL型滤波器对单相光伏并网逆变器进行滤波,LLCL滤波器通过在传统LCL滤波器的电容支路中串联一个小的电感达到在开关频率处产生串联谐振,相比LCL型滤波器能够更大程度地对串联谐振频率处的电流谐波进行衰减,可以减少电感装置的体积和重量,减少动态响应时间。更重要的是,能够减少电网侧的电感值,这样可以提高特征谐振频率点,有利于并网逆变器的控制。对比分析了传统LCL滤波器和LLCL滤波器的性能,证实和评估LLCL滤波器的优越性。对LLCL滤波器进行了参数设计,使用Matlab仿真软件搭建模型,仿真结果表明系统具有较好的稳态性能,且抗干扰性能好。

The paper proposes a new topology of a high pole filter-LLCL filter, which is used to eliminate the harmonics in the single-phase photovoltaic grid-connected inverter. LLCL filter can be constructed through insertion a small inductance at the capacitor branch of traditional LCL filter, which can cause series resonance at the switching frequency. Compared with the traditional LCL filter, the LLCL filter can not only eliminate the current harmonics of series resonance frequency greater, but reduce the volume and weight of inductance devices and accelerate the dynamic response. What is more important is that the LLCL filter can decrease the grid-side inductance, which can increase the characteristics resonant frequency and simplify the control of photovoltaic grid-connected inverter. The paper give a comparison of the LCL filter and LLCL filter, verifying the LLCL filter has a huge superiority. At the same time, the paper gives a specific parameter design for LLCL filter, which can be tested by MATLAB. Finally, the simulation results show that the LLCL filter has good steady-state and anti-interference performance.