PRBS-Based Impedance Measurement Tool for Stability Analysis of Black-Box EMT Models in PSCAD

The challenges of integrating inverter-based resources (IBRs), especially low-frequency instability, are globally concerning. While current responses mainly rely on time-domain simulation to replicate and mitigate such oscillation incidents, the significance of frequency-domain analysis cannot be overlooked. This paper emphasizes the black-box modeling approach, overcoming limitations posed by the lack of detailed vendor information. A pseudo-random binary sequence -based impedance measurement tool (PRBS-based IMT) is developed for stability analysis in PSCAD, enabling thorough IBR-based power system analysis in frequency-domain. After accurately measuring the dq impedance components for the entire system (load and source subsystems) and presenting results via Bode plots, stability analysis is conducted in Python using the generalized Nyquist criterion (GNC). Findings are validated through several case studies, including analytical model comparisons and time-domain simulation. The PRBS-based IMT aims to provide reliable insights into dynamic characteristics and stability of commercialized IBR-based power systems modeled in PSCAD.