Interaction analysis of multi VSCs integrated into weak grid in current control time-scale

This paper investigates the dynamic interaction of multi grid-connected voltage source converters (VSCs) in the current control time-scale. To illustrate the physical mechanism of interaction, a model is proposed based on the physical motion law of VSC's controlled current in frequency domain. The proposed model distinguishes the current control of VSCs into two branches, namely the self-stabilizing loop and interacting loop, according to their different physical influences on the inductor current. The analysis of a two-converter system reveals that the interaction caused by fast dynamic current control can decrease the positive damping on controlled current through the interacting loop and deteriorate system stability. Time-domain simulation results of a two-converter system implemented in MATLAB/Simulink validate the correctness of analysis and the effectiveness of the proposed model.