Generalized Impedance-Based Stability Analysis for System- Level Small-Signal Stability Assessment of Large-Scale Power Electronics-Dominated Power Systems

This paper proposed the generalized impedance- based stability analysis (GISA), which can provide a global view of system dynamics using the pure black-box impedance/ admittance models, and meanwhile identify the most effective impedance shaping methods for system stability enhancement. So it can be readily used for the design-oriented system-level stability analysis of large-scale power electronics-dominated power systems with real-life complexities. With the proposed method, the dynamic interactions among an arbitrary number of subsystems are translated as multiple decoupled single-input single-output (SISO) minor loops in the frequency domain, of which the stability can be readily assessed by the SISO Nyquist stability criterion. Moreover, the oscillation mode shape of the terminal voltages and currents are derived mathematically. Furthermore, the frequency-domain participation factor is defined to identify the most contributive components for the oscillations, and also provides the most effective impedance shaping solution for stability enhancement. The electromagnetic transient (EMT) simulation results from an 800MW offshore wind energy system with a real-life complexity confirm the effectiveness of the proposed method.