Grid-connected inverters is the core component of distributed generation system, and the filter is the core component of the inverters. When the inverter works, the filter can effectively filter and suppress the high-frequency harmonics in the output current of the inverter side, so as to ensure the stability of the power grid and improve the working effect of the whole grid connected inverter system. The filter is a high order underdamped system, and the LLCL Filter also has a resonance peak. In this paper, a weighted current method based on active damping is used. In this method, the output current of the inverter side and the current of the grid side are weighted with a reasonable proportion as the feedback quantity, the weighted current feedback is the outer loop, and the LC series branch current feedback is the inner loop. The system is reduced to the first order theoretically, which makes up for the under damping problem of the system and suppresses the resonance peak of the system. Through the simulation experiment, the feasibility of the active damping weighted current method is verified.
Simulation of LLCL filter based on active damping weighted current control strategy
