采用LCL滤波器的并网逆变器双闭环入网电流控制技术

Dual-loop Grid Current Control Technique for Grid-connected Inverter Using An LCL Filter

并网逆变器采用LCL滤波对高次谐波衰减效果显著,而且在低开关频率和电感较小的情况下较单电感滤波具有明显的优势。但是,LCL为无阻尼3阶系统,易发生谐振。研究采用并网电流和电容电流双闭环控制策略对并网电流进行控制,采用电容电流闭环增加系统阻尼,从而可抑制系统振荡,增加系统稳定性。对电流双闭环方案进行系统建模和稳定性分析,并进行仿真验证。最后,采用电流双闭环控制策略进行并网实验,实验结果表明,该方案可有效地避免进网电流谐振和实现进网电流的高功率因数。

Grid connected inverter frequency harmonics effectively through can attenuate high an LCL filter which has potential benefits for the inverter to get higher harmonic performance with lower switching frequency and less inductance in contrast with L filter. However, LCL filter is a third order system without damping and easy to resonate. In order to eliminate resonance and improve system stability, dual-loop control strategy with grid current feedback and capacitor current feedback was proposed in this paper, where inner capacitor current regulation is adopted for active damping System modeling and stability analysis were presented. The simulation and experiment results proved that the dual-loop current control strategy for grid-connected inverter with LCL filter is feasible, the resonance of grid current is avoided and high in-grid power factor is achieved.