Abstract:

In order to solve the problem of large working capacity and high loss of active damper caused by the fixed virtual resistance value,the virtual resistance adaptive control strategy based on Fourier transform is proposed.Taking the grid-connected inverter with the resonance stability as the object,the reason of resonance in the inverter is analyzed,the stability of the system is corrected by designing the virtual resistance of the active damper.Finally,the magnitude of the resonance voltage component is extracted at the common coupling point according to the Fourier transform,and the value of the virtual resistance dynamically is adjusted,so as to make the active damper work at a lower capacity and provide the suitable damping for the system at the same time.Simulation shows that the proposed strategy can effectively suppress the resonance of the voltage at the point of common coupling,effectively reduce the working capacity of the active damper at the same time,and improve the ability of the active damper to solve the resonance problem.

Key words: active damper, weak grid, Fourier transform, virtual resistance adaptive