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

To address the growing dynamic issues in the power electronics-based power system, this paper proposed an enhanced impedance-based stability analysis which can not only obtain the global view of system dynamics, but also provide a tailor-made stabilization solution by the direct use of the measured black-box models. With the proposed method, the dynamic interactions at selected multiple ports of the system 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 shapes, i.e., the relative magnitude and phase of oscillated voltages and currents at the selected ports, are derived mathematically. Furthermore, the frequency-domain participation factor is defined to identify the most contributive components for the oscillations; Through impedance shaping solution of the corresponding oscillatory mode, it also provides the most effective system stability enhancement solution. EMTDC/PSCAD time-domain simulation results from an 800MW offshore wind energy system with a realistic complexity confirm the effectiveness of the proposed method.