Multi-Domain-Mapping-Based Impedance Calculation Method for Oscillatory Stability Analysis of VSC-Based Power System

Voltage source converter (VSC)-based power systems are characterized by oscillations with extensive propagation, wide-band responses, and complex multi-modal coupling. Analyzing the stability of these systems poses significant challenges due to their high-order features and the need for flexible analysis models. To address these issues, this paper proposes a novel multi-domain-mapping (MDM) based impedance calculation method, notable for its efficiency, flexibility, and precision. The discrete-time small-signal models (DT-SSMs) at the component level are established replace conventional continuous-time SSMs (CT-SSMs). Furtherly, the subsystems are described using the nodal analysis method (NAM), and then directly equivalent to portal equivalent SSMs (PE-SSMs). By leveraging the superposition theorem and mapping between the z-plane and s-plane, the admittance and impedance matrices in discrete-frequency (DF) and continuous-frequency (CF) domains are derived. This method facilitates the straightforward construction of system-level models and the efficient acquisition of impedance for large-scale systems, making it readily implementable on computers. The accuracy and efficiency of this method are validated through comparisons with existing analytical calculation methods, frequency scanning methods, and time-domain simulations in cases of a VSC-based microgrid and a wind farm.