In the three-phase LCL grid connected inverter system

due to the interaction between equipment and system

harmonic oscillation may occur

which seriously affects the normal operation of the system. In order to solve this problem

the harmonic linearization method is adopted to modify the impedance model considering the influence of grid side voltage of coupling compensation term

and the modified sequence impedance model of three-phase LCL grid connected inverter is established. At the same time

stability analysis is conducted from the perspective of resonance principle and logarithmic frequency stability to reveal the generation mechanism of high-frequency resonance in photovoltaic grid connected system. The impedance characteristic curve is taken into consideration

the parameters of the damping link are selected

and the impedance is reconstructed in the frequency band which is easy to oscillate. Finally

based on the Matlab/Simulink simulation platform

the correctness and effectiveness of the method are verified. The results show that the additional active damping link can effectively suppress harmonic oscillation and has good dynamic characteristics.