Python Comtrade

Python Comtrade is a module for Python 3 designed to read Common Format for Transient Data Exchange (COMTRADE) files. These consists of oscillography data recorded during power system outages, control systems tests, validation and tests of field equipment, protective relaying logs, etc. The COMTRADE format is defined by IEEE Standards, summarized in the table below. Some equipment vendors put additional information in proprietary versions of it. This module aims IEEE definitions but may support those proprietary versions.

Installation

pip install comtrade

Or just copy comtrade.py from this repository.

Requirements

• Python 3.11 or newer
• (optional) numpy for speed improvement: pip install "comtrade[numpy]"
• (optional) pandas for data frame support: pip install "comtrade[pandas]"

How to Use

The examples below shows how to open both CFG and DAT files or the new CFF file to plot (using pyplot) analog channel oscillography.

CFG and DAT files (all revisions)

Comtrade files separated in CFG and DAT formats can also be read with load function. A CFG file path must be passed as an argument and, optionally, a DAT file path too (if the file name is not equal of the CFG file).

import matplotlib.pyplot as plt
import comtrade

rec = comtrade.load("sample_files/sample_ascii.cfg", "sample_files/sample_ascii.dat")
print("Trigger time = {}s".format(rec.trigger_time))

plt.figure()
plt.plot(rec.time, rec.analog[0])
plt.plot(rec.time, rec.analog[1])
plt.legend([rec.analog_channel_ids[0], rec.analog_channel_ids[1]])
plt.show()

It will read the contents of additional header (*.hdr) and information (*.inf) files. Their contents are available through Comtrade.hdr and Comtrade.inf properties.

CFF files (2013 revision)

import matplotlib.pyplot as plt
import comtrade

rec = comtrade.load("sample_files/sample_ascii.cff")
print("Trigger time = {}s".format(rec.trigger_time))

plt.figure()
plt.plot(rec.time, rec.analog[0])
plt.plot(rec.time, rec.analog[1])
plt.legend([rec.analog_channel_ids[0], rec.analog_channel_ids[1]])
plt.show()

The module function load must be called with the CFF file path specified.

Comtrade.analog and Comtrade.status lists stores analog and status channel sample lists respectively. These can be accessed through zero-based indexes, i.e., Comtrade.analog[0]. The list Comtrade.time stores each sample time in seconds.

Analog channels may have a time skew (in microseconds) from the start of the sample period, which is not included in Comtrade.time. The list Comtrade.analog_time stores the time values of each analog channel, with its skew, in seconds, i.e., Comtrade.analog_time[0] for Comtrade.analog[0].

More information can be accessed through Comtrade.cfg object, which stores data such as detailed channel information.

Data of additional sections, such as HDR and INF, can be accessed through hdr and inf properties, respectively.

Data frames

The module supports the use of pandas.DataFrame as a data structure. Use the conveninent function load_as_dataframe or call Comtrade.to_dataframe() function after loading the data.

import comtrade
df = comtrade.load_as_dataframe("sample_files/sample_ascii.cfg")
print(df.head())

# Or, alternatively
rec = comtrade.load("sample_files/sample_ascii.cfg")
df = rec.to_dataframe()
print(df.head())

Features

This module implements some of the functionality described in each of the Standard revisions. The tables below lists some features and file formats and which revision supports it. It also shows whether this module support the feature or the format.

Feel free to pull requests implementing one of these unsupported features or fixing bugs.

Unsupported features

• Nanoseconds time base within Python's datetime objects (such as start_timestamp and trigger_timestamp properties). It warns the user but doesn't use it, truncating the numbers.

Additional settings and features

Numpy arrays as data structures

The use of numpy.array as a data structure to hold time, analog and status data can be enforced in Comtrade object constructor:

obj = Comtrade(use_numpy_arrays=True)

It may improve performance for computations after loading data. It also speeds up loading binary DAT files (BINARY, BINARY32 and FLOAT32 formats), which are converted with vectorized numpy operations.

Replace missing data with float('nan')

Missing analog values are replaced with float('nan'). The value used to represent missing data varies with the Comtrade dat format and revision year. These are listed in the table next.

File encodings

Specify the encoding as a keyword argument on all load methods as you'd specify for common file loading:

import comtrade
comtrade.load("sample_files/sample_ascii.cff", encoding="iso-8859-1")

Documentation

https://github.com/dparrini/python-comtrade

Support

Feel free to report any bugs you find. You are welcome to fork and submit pull requests.

Development

From a clone of the GitHub repository, run the tests and the linter with uv:

uv run pytest
uv run ruff check

Or, with pip 25.1 or newer:

python -m pip install -e . --group dev
python -m pytest

Releasing

1. Update __version__ in comtrade.py and push the commit to master.
2. Publish a GitHub release tagged with that same version, e.g. gh release create 0.1.3 --generate-notes.

The Release workflow then runs CI and uploads the sdist and wheel to PyPI using Trusted Publishing, so no API token is needed.

License

The module is available at GitHub under the MIT license.