Pre-Processed Power Grid Frequency Time Series

Overview
This repository contains ready-to-use frequency time series as well as the corresponding pre-processing scripts in python. The data covers three synchronous areas of the European power grid:

• Continental Europe
• Great Britain
• Nordic

This work is part of the paper "Predictability of Power Grid Frequency"[1]. Please cite this paper, when using the data and the code. For a detailed documentation of the pre-processing procedure we refer to the supplementary material of the paper.

Data sources
We downloaded the frequency recordings from publically available repositories of three different Transmission System Operators (TSOs).

• Continental Europe [2]: We downloaded the data from the German TSO TransnetBW GmbH, which retains the Copyright on the data, but allows to re-publish it upon request [3].
• Great Britain [4]: The download was supported by National Grid ESO Open Data, which belongs to the British TSO National Grid. They publish the frequency recordings under the NGESO Open License [5].
• Nordic [6]: We obtained the data from the Finish TSO Fingrid, which provides the data under the open license CC-BY 4.0 [7].

Content of the repository

A) Scripts

1. In the "Download_scripts" folder you will find three scripts to automatically download frequency data from the TSO's websites.
2. In "convert_data_format.py" we save the data with corrected timestamp formats. Missing data is marked as NaN (processing step (1) in the supplementary material of [1]).
3. In "clean_corrupted_data.py" we load the converted data and identify corrupted recordings. We mark them as NaN and clean some of the resulting data holes (processing step (2) in the supplementary material of [1]).

The python scripts run with Python 3.7 and with the packages found in "requirements.txt".

B) Yearly converted and cleansed data
The folders "<year>_converted" contain the output of "convert_data_format.py" and "<year>_cleansed" contain the output of "clean_corrupted_data.py".

• File type: The files are zipped csv-files, where each file comprises one year.
• Data format: The files contain two columns. The second column contains the frequency values in Hz.  The first one represents the time stamps in the format Year-Month-Day Hour-Minute-Second, which is given as naive local time. The local time refers to the following time zones and includes Daylight Saving Times (python time zone in brackets):
  • TransnetBW: Continental European Time (CE)
  • Nationalgrid: Great Britain (GB)
  • Fingrid: Finland (Europe/Helsinki)
• NaN representation: We mark corrupted and missing data as "NaN" in the csv-files.

Use cases
We point out that this repository can be used in two different was:

• Use pre-processed data: You can directly use the converted or the cleansed data. Note however, that both data sets include segments of NaN-values due to missing and corrupted recordings. Only a very small part of the NaN-values were eliminated in the cleansed data to not manipulate the data too much.

• Produce your own cleansed data: Depending on your application, you might want to cleanse the data in a custom way. You can easily add your custom cleansing procedure in "clean_corrupted_data.py" and then produce cleansed data from the raw data in "<year>_converted".

License

This work is licensed under multiple licenses, which are located in the "LICENSES" folder.

• We release the code in the folder "Scripts" under the MIT license .
• The pre-processed data in the subfolders "**/Fingrid" and "**/Nationalgrid" are licensed under CC-BY 4.0.
• TransnetBW originally did not publish their data under an open license. We have explicitly received the permission to publish the pre-processed version from TransnetBW. However, we cannot publish our pre-processed version under an open license due to the missing license of the original TransnetBW data.

Changelog
Version 2:

• Add time zone information to description
• Include new frequency data
• Update references
• Change folder structure to yearly folders

Version 3:

• Correct TransnetBW files for missing data in May 2016