Current Limiting Strategy of Grid-forming Converter Based on Additional Current Loop

Abstract

After the falut of the new energy unit during the grid connection, due to the limited current carrying capacity of the converter, the device will be damaged which can result in the unit off grid operation the grid. In order to solve the above problems, this paper first discusses the main problems existing in the control of existing grid-forming (GFM) converters under grid fault conditions. Then, an additional current control strategy is proposed to control the current components of dq-axis respectively. On the premise of ensuring that the output current of the converter within the allowable range, the proposed strategy guarantees the voltage source characteristics of the converter during the fault period. Finally, the effectiveness and superiority of the proposed control strategy are verified by MATLAB/Simulink simulation.