Single Current Feedback Control for LCL Grid-connected Inverter Based on Tracking Differentiator

LCL filter is widely used in grid-connected inverter system. Compared with $L$ filter, it has good attenuation effect on high harmonics. However, LCL filter is a third-order system with low damping, and is very easy to resonate. Active damping is an effective measure to solve the resonance problem of LCL filter. The traditional grid-connected current feedback active damping is difficult to extract differential signals, poor dynamic performance and poor noise suppression. Therefore, single current feedback control strategy for LCL grid-connected inverter based on tracking differentiator is proposed in this paper. The third-order tracking differentiator (TD) is designed to extract the second-order differential signal of the grid-connected current as the feedback control of active damping in order to suppress the resonance and the noise. As a result, performance of the dynamic response when the grid-connected current is suddenly changed and the noise suppression are improved. Simulation results demonstrate the effectiveness of the proposed method.