Parameterizing Operating-Point-Dependent IBR Using Coherent Operating Regions for Sub-synchronous Oscillation Analysis
For power system engineers analyzing SSO in IBR-dominated grids, this work addresses the challenge of capturing heterogeneous IBR dynamics across operating conditions, but the validation is limited to a single test system.
The paper proposes a framework to parameterize operating-point-dependent IBR dynamics for sub-synchronous oscillation analysis by identifying coherent operating regions using singular value decomposition and linear regression, enabling accurate system-level frequency-response and modal analysis without repeated scans. Validation on a modified IEEE 39-bus system shows the parameterized responses accurately reconstruct system-level dynamics.
Analysis of sub-synchronous oscillations (SSO) in IBR-dominated grids relies on frequency scan-based estimation of black-box IBR models at selected operating points. Since IBRs may operate over a wide range of operating conditions, frequency responses obtained at a limited number of operating points may not adequately represent the dynamics required for system-level SSO analysis. Accurate parameterization of operating-point-dependent IBR dynamics is challenging due to the heterogeneous dynamic behaviors that may arise across the operating space. This paper addresses this challenge by analytically characterizing the conditions that give rise to discontinuous and non-smooth variations in IBR dynamics. Leveraging these insights, a geometric representation based on singular value decomposition is used to identify coherent operating regions and partition the operating space into dynamically consistent regions. Within each region, the operating-point dependence of the IBR frequency response is accurately captured using simple linear regression. The proposed framework is validated on a modified IEEE 39-bus system. Results demonstrate that the parameterized IBR frequency responses accurately reconstruct system-level dynamics at the prevailing operating condition, enabling frequency-response and modal analysis without repeated system-level frequency scans.