Combining virtual synchronous machine and feedforward torque control for doubly-fed induction machine based wind energy conversion systems

The number of directly grid-connected synchronous machines (SMs) forming the grid voltage decreases. Thus, the risk of power system instability increases, especially regarding the grid frequency due to the decreasing power system inertia. Grid-forming (GFM) control of inverter-based resources (IBRs) with inertia emulation capability is required to face these challenges and to guarantee reliable operation of the future power system. This paper proposes virtual synchronous machine (VSM) control for doubly-fed induction machine (DFIM) based wind energy conversion systems (WECS) that (i) enables feed-forward torque control (FTC) and thus, does not degrade the WECS performance during normal operation, (ii) adapts the VSM damping based on the DFIM operating point, and (iii) protects the VSM against overloading to avoid loss of synchronism.