VSM With Improved Transient Dynamics Based on Generalized Slip Frequency

In this article, the slip mechanism in the rotor-dynamics of the induction machine is emulated to improve the transient stability of grid-forming converter (or virtual synchronous machine). Different from the synchronous machine, the speeds of the rotor and of the rotating magnetic field in the stator are different in the induction machine. This slip frequency in the induction machine offers another degree-of-freedom to regulate the frequency, playing a similar role of the damper winding in the synchronous machine. It can inject transient damping to the system, and virtually increase the feedback power to smooth the power angle variations when severe fault occurs. The effectiveness of the proposed controller on improving both small-signal and transient stability (large-signal) is presented. The proposed algorithm is verified by experiments.