Impedance Modeling and Stability Analysis for Multi-loop Control of Grid-forming Converter
The control method of grid-forming converter can be divided into single loop control with only power con-trol loop and multi loop control with power control loop and voltage and current control dual loop based on the ex-istence of voltage and current control dual loops.There are significant differences in the characteristics of grid con-nected operation between the two control methods in different frequency bands.This article first establishes a multi loop control sequence impedance model for a grid type inverter considering voltage and current decoupling control,and compares and analyzes the impact of two control methods on the output impedance of the inverter.Secondly,to address the issue of insufficient low-frequency phase margin caused by the addition of voltage and current control dual loops,a virtual impedance method is proposed to improve the stability of the converter grid connection.Finally,the accuracy of stability analysis was verified through simulation and experiments.
grid-forming convertervoltage and current control double loopsequential impedancegrid connection sta-bilityvirtual impedance
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