Test Cases Library of Power System Sustained Oscillations

Cases of actual oscillatory events (Back to the homepage)

This page contains a collection of oscillatory events in actual power systems in a form of PMU data measurements collected from multiple locations of power systems during these oscillatory events.

Power utilities and other relevant entities are encouraged to submit more test cases. Larger set of test cases provides better testing opportunity for the developers of new source location methods and practical tools. Actually observed sustained oscillations in power system have multiple attributes. Practically meaningful tool for locating the source of oscillations should be capable to locate the source for at least for majority of possible oscillations. From that prospective, adding new test cases with attributes of oscillations not covered by already submitted cases is very useful.

This document describes the requirements to data preparation in "IEEE.csv" format and submission:


This Matlab code is useful for the verification of the consistency of the prepared PMU data set with the requirements:


Please make sure to verify your case with this software before submitting it.

     ➤List of actual PMU data sets capturing oscillatory events in real power systems (Click case # for download)

Cases # Case name Data of event Power system - source of PMU Type of oscillations Frequency/Hz Peak to peak magnitude Source and location Confidence level on the source location Duration of sample set Comments
1 ISO-NE case 1 Jun.17, 2016 ISO-NE System-wide mode 0.27 Up to 27 MW Generator outside of ISO-NE in Area 2. 100% 3 min Near-resonance conditions with system-wide natural oscillatory mode caused by a large generator located in Area 2. Area map: ISO-NE_map.pdf.
2 ISO-NE case 2 Oct.3, 2017 ISO-NE Multi-frequency, wide-spread Dominant modes:
Up to 130 MW Generator outside of ISO-NE in Area 3. 100% 6 min Multi-frequency process with growing magnitude caused by a generator located outside of ISO-NE in Area 3. Oscillations with significat MW magnitude were observed in multiple locations. Area map: ISO-NE_map.pdf.
3 ISO-NE case 3 Jul.20, 2017 ISO-NE Regional 1.13 Up to 115 MW Generator located East from Sub:2. Lines Ln:2 and Ln:4 lead to the area, where the source generator resides. 100% 3 min Equipment issue in a large generator has created 1.13Hz oscillations with growing magnitude during 40 seconds.
4 ISO-NE case 4 Feb.14, 2018 ISO-NE Wide-spread 0.25 Up to 10 MW Presumably outside of ISO-NE. Low 5 min Sustained oscillations with variable magnitude and observed in multiple locations.
5 ISO-NE case 5 Jan.29, 2018 ISO-NE Local 1.57 Up to 15 MW Generator Gen2 at Sub:7. 100% 4 min Local oscillations caused by a large generator. An ISO-NE map in PDF is provided with data.
6 ISO-NE case 6 June.20, 2019 ISO-NE Local 0.14 Up to 9 MW A power plant radially connected by the line Ln:2. High 20 min PMU data set includes PMU measurements of all four 345 kV transmission lines Ln:1...Ln:4 connected to the substation Sub:1. The 0.14 Hz oscillations with relatively high magnitudude were observed locally in the power system. Also, the 0.14 Hz frequency is below the lowest frequency of natural modes in the Eastern Interconnections suggesting that the case is NOT a "resonance conditions". Both facts allows to conclude with high confidence level, that the magnitude of oscillations in this case is indicative to the source and the source of oscillations is the power plant located behind Ln:2. That power plant is radially connected to the network by the Ln:2 only. The specific of this case is that the Dissipating Energy Flow (DEF) or energy-based method result in the non-monotonic flow of transient Dissipating Energy (DE) coming from the line Ln:2. The interpretation of that fact means that the power plant could be classified as the source or sink of oscillations depending on studied time interval. It is not clear on whether the above intepretation reflects reality where the non-monotonic flow of DE is caused by the fluctuation of actual forced signal at the power plant or the non-monotonic DE is artifact potentially caused by inaccuracies of PMU processing, bad PMU data or other unknown yet factors. The nature of actual forced signal at the power plant is unknown.