Inertia Characteristics Analysis of DFIG-Based Wind Turbines with Virtual Synchronous Control in Different Operation Areas

Large-scale integration of wind power reduces the inertia of power system, causing the deterioration of frequency dynamics. Equipping doubly fed induction generator (DFIG)-based wind turbines (WTs) with virtual synchronous control (VSynC) is an effective way to provide the desirable inertia support for power system. Although the inertia characteristics of DFIG-based WTs with VSynC were studied in some literature, the impact of different operation areas, where WTs' working mode is different, on the inertia characteristics were barely focused. Based on the concept of motion equation, this paper presents a motion model of DFIG-based WTs considering the influences brought by different operation areas. Frequency-domain expressions of the inertia of DFIG-based WTs with VSynC in different operation areas are derived and the physical meaning of the inertia expression is explained. Then the inertia characteristics in different operation areas are studied and compared. Time-domain simulations of a typical system are conducted to verify the correctness of the analysis.