Comparative Study of Coupling Characteristics Between Machine- and Grid-side Subsystems of PMSG-based WTGs under Different Control Modes

The permanent magnet synchronous generator (PMSG)-based wind turbine generator (WTG) has become the mainstream in wind power generation. However, the wideband oscillation issues have become increasingly serious due to the interaction of PMSG-based WTGs and the grid. It is generally considered that the interaction characteristics almost completely depend on the grid-side subsystem (GSS), so that the machine-side subsystem dynamics (MSSD) are usually ignored in existing researches. The rationality of such simplification method has not been systematically studied. Therefore, the comparative study of coupling characteristics between machine- and grid-side subsystems of PMSG-based WTGs under four types of control modes is carried out in this paper. Firstly, the detailed impedance models of PMSG-based WTGs under these control modes are developed and validated. Based on these impedance models, the comparative analysis of coupling characteristics is carried out qualitatively and quantitatively. Some useful findings are obtained. Finally, the case study verifies the impact of such coupling effects on the stability analysis of gird-connected PMSG-based WTGs.