Sub-/Super-SCI Influencing Factors Analysis of VSC-HVDC and PMSG-Wind Farm System by Impedance Bode Criterion

A sub-/super-synchronous interaction (sub-/super-SCI) can occur between a voltage source converter-based high-voltage direct current (VSC-HVDC) and the permanent magnet synchronous generator (PMSG)-based wind farms with long AC transmission lines. However, influencing factors have not been properly analyzed. In this paper, these are deconstructed mathematically analyzed from detailed small-signal impedance equations in dq-frame corresponding Bode stability criterion. Distinguishing conclusions existing papers obtained by studying controllers’ bandwidths instead of their coefficients. The impacts line on system also investigated. From analysis compositions structure, VSC-HVDC farm phase-locked loop (PLL) bandwidth power ratio, various influences stability. Meanwhile, outer DC inner control little impact results studies show that magnitude axes q-axes is essential factor for instability. Our more sensitive to HVDC than converter PLL bandwidth. simulation verify our theory conclusions.