Try on ENTSO-E web site.

https://www.entsoe.eu

My knowledge on this is some year old. Based on that I think there is a need for adequately well doucumented PMU and similar instrument measurements from different locaions in the Nordic power system, having better continuity than individual projects and available for relevant researchers. The details on the instrument type and model are relevant. What else?

These websites may be useful for you:

1-Access Data via Encore Series System

Electrotek’s Encore Series System live demonstration units are located at the service entrance and the substation that supplies our office. Clicking on this link enables you to see up-to-the-minute information, including real-time data, trends, and events for the past 30 days. Internet Explorer is required and first-time users will need to download supporting Java classes.

http://infonode.electrotek.com/

userid: guest / password: password

2- Access Power Quality Data via PQWeb

Electrotek’s PQWeb program provides access to downloaded and processed data that is stored in a PQView database. Clicking on this link enables you to view events, trends, and reports for data gathered for these sites during the past year.

http://www.powermonitoring.com/pqweb

serid: powermondemo / password: electrotek

3-Download Reports

Download a sample single-site power quality summary report that was created using PQView's report writing capability.

http://www.powermonitoring.com/sample.pdf

Also you can access to another datasets here :

http://sites.ieee.org/pes-iss/data-sets/

Also authors of this book have collected usefull data which is public accessible :

Book : Time-Varying Waveform Distortions in Power Systems

edited by Paulo Fernando Ribeiro-Wiley 2009

Data source : Wiley website of the book - resources