评估多样化可再生能源发电单元频率支撑能力的统一方法

The proliferation of renewable power generation units (RGUs) deteriorates the physical inertia of the system, making the evaluation of unit-level frequency support capability (FSC) and system-level frequency stability increasingly important. However, the prior-art approaches lack a standardized framework for FSC assessment, and the non-disclosure of RGU information by manufacturers exacerbates this challenge. To address these issues, this paper proposes a unified transfer function structure (UTFS) model and its parameter solving method based on impedance measurement, enabling a unified assessment of both the unit-level FSC and system-level frequency stability. The unit-level UTFS can be obtained through frequency-domain approaches, e.g., xy-impedance measurements. Moreover, the system-level UTFS can be acquired through the simple aggregation of unit-level UTFS. Without detailed models or post-event data, the proposed framework uniformly represents the FSC of various RGUs through three key indicators: effective inertia, damping, and primary frequency regulation (PFR). Furthermore, the proposed method analytically derives system frequency indicators: frequency nadir, rate of change of frequency (RoCoF), and steady-state frequency deviation. Numerical simulations and analysis of the operational data of a provincial power grid are provided to validate the proposed method.