Laboratory Characterisation of PMU-based Detection of Sub-Synchronous Oscillation
Stefano Lodetti(1), Frederick Wilkins(1), Peter Davis(1), Sahara Moshref(1), Paul Wright(1), Guglielmo Frigo(2), Deborah Ritzmann(1) 1. National Physical Laboratory, Hampton Road, Teddington, United Kingdom 2. Federal Institute of Metrology, Bern, Switzerland 2026-06-27

Abstract

This paper presents a laboratory study of thelimitations and capabilities of sub-synchronous oscillations (SSOs) detection with a phasor measurement unit (PMU), with particular focus on amplitude attenuation. A test-bench to analyse the frequency response of a commercial PMU is presented, showing significant attenuation occurring outside the nominal system frequency range, which complicates the detection of SSOs. Experimental results demonstrate that while a PMU can detect SSOs under ideal conditions, attenuation and modulation effects can lead to misidentification or missed detections. The study highlights the need for advanced detection techniques and configurable PMU parameters to improve reliability in SSO monitoring.

Key words: small-signal stability, sub-synchronous oscillations, phasor measurement units, inverter-based resource, power system measurements

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