Fast Power Regulation Method During System Restoration for D-PMSG-Based Wind Turbines

The speed of the pitch action is one of the primary constraints that limit the power ramp rate of wind turbines (WTs). By storing kinetic energy (KE) within the wind wheel, blades, and generator rotor, the output power of the WT can be regulated more rapidly with less pitch action. This capability is beneficial in specific situations where additional power injection is required by the external system, such as during the system restoration process after a blackout. In this paper, a novel fast power regulation method for direct-drive PMSG-based (D-PMSG-based) WTs is proposed. This method allows for the early completion of the most time-consuming pitch reduction process and ensures that KE can be stored within the WT before the external system becomes available. As a result, the WT will be able to achieve maximum power output before the system restoration is fully completed. The potential operation boundary and the maximum external power support capability of D-PMSG-based WTs are analyzed. By following the operation boundary, converter modulation problem caused by high KE reserve can be avoided. The proposed fast power regulation method can significantly reduce the power increase speed and maximize the output power capability of D-PMSG-base WTs.