Optimal WMU Placement Based on a Composite Fault Sensitivity for Monitoring IBR Dynamics

This paper proposes a Fault Sensitivity (FS)-based optimal placement strategy for Waveform Measurement Units (WMUs) to enhance the monitoring of complex dynamics in Inverter-Based Resources (IBRs)-dominated power systems. Overcoming the limitations of conventional, topology-only Measurement Redundancy (MR) methods, this study develops eight quantitative FS indices derived from Electromagnetic Transient (EMT) simulations to evaluate the physical response of each bus to transient and oscillatory events. In case studies on the IEEE 14-bus and 30-bus systems under Single-Line-to-Ground (SLG) fault and Sub-Synchronous Oscillation (SSO) scenarios, the proposed FS-based placement improved the integrated sensitivity score by up to 12.0% and 57.3%, respectively, compared to the MR-based approach. Physical waveform analysis further validates that the proposed method successfully identifies optimal observability points that most clearly capture critical dynamic phenomena, such as the inter-area propagation of electromechanical oscillations.