Unveiling Transmission Line Vulnerabilities to Power Swing with Higher-Order Dynamic Mode Decomposition

The large-scale integration of inverter-based resources (IBR) is fundamentally altering power system dynamics by introducing new challenges to traditional protection schemes. One critical issue comes out during power swings, where the dynamics of voltage angle differences across transmission lines are significantly impacted by IBR penetration. This will directly influence the rate of change of impedance (ROCI) sensed by transmission line relays, potentially affecting the effectiveness of power swing blocking schemes. This paper addresses the essential necessity of identifying the transmission lines and relays most affected by IBR penetration, based on their ROCI, a problem that has received very limited attention in existing research. Employing the data-driven Higher-Order Dynamic Mode Decomposition, the methodology discussed in the paper extracts and analyzes the angular difference dynamics of transmission lines following large disturbances. The proposed methodology offers system-level interpretability by approximating the Koopman operator and extracting state-consistent mode shapes and spatio-temporal oscillation features. This facilitates a deeper understanding of how IBR penetration impacts individual transmission lines. The proposed approach is validated on a modified IEEE 39-bus system and the Northern Regional Power Grid of India, demonstrating its effectiveness in capturing angular dynamics and identifying critical transmission lines and relays impacted by IBR penetration.