基于双馈感应发电机的风电机组时变惯量表征方法用于电力系统频率动态分析

Accurately assessing the inertial response of renewable energy generation (REG) is critical for frequency stability. However, REG represented by doubly-fed induction generator (DFIG)-based wind turbine (WT) exhibits inherent time-varying inertia behavior, fundamentally distinct from synchronous generators (SGs). Prevailing inertia assessment methods predominantly rely on SG-derived time-domain inertia constants, which cannot capture this intrinsic variability. Consequently, the rationality of directly applying these conventional methods to DFIG-based WT lacks theoretical justification. To address this gap, this paper derives an expression for calculating time-varying inertia using the angular momentum theorem. Results demonstrate that inertia in the time domain dynamically varies with disturbances, highlighting the significant limitations of conventional inertia descriptions. Alternatively, a frequency-domain inertia characterization method is investigated to provide a disturbance-independent description of inertia, effectively capturing its intrinsic time-varying nature. Due to the duality between time and frequency domains, this paper mathematically describes the relationship between frequency-domain inertia and time-domain inertia, explicitly clarifying the physical meaning of inertia in the frequency domain. Simulations on an IEEE 39-bus system verify that the frequency-domain inertia method accurately captures inertia dynamics and is suitable for frequency stability analysis. These findings emphasize frequency-domain inertia characterization as an essential method for representing inertia in renewable-rich power systems.