Overview

A package containing functionality to compute ampacity line ratings for overhead lines. Currently, the package only contains equations from CIGRE TB 601.

Installation

pip install linerate

Documentation

This library is split into four main parts:

1. The equations module, which contains one pure function for each equation in CIGRE TB 601,
2. the types module, which contains datatypes for conductors, weather parameters and spans,
3. the model module, which contains a wrapper class Cigre601 to easily compute the ampacity and conductor temperature based on a Span and Weather instance,
4. and the solver module, which contains a vectorized bisection solver for estimating the steady state ampacity and temperature of a conductor.

A typical user of this software package will only use the types and model module, and the model module will then use functions from equations and solver to estimate the conductor temperature and ampacity. However, to understand the parameters, it may be useful to look at the functions in the equations module, as we have taken care to ensure that the argument names stay consistent.

Below, we see an example of how to compute the conductor temperature based on Example B on page 79-81 in CIGRE TB 601.

import numpy as np
import linerate


conductor = linerate.Conductor(
    core_diameter=10.4e-3,
    conductor_diameter=28.1e-3,
    outer_layer_strand_diameter=2.2e-3,
    emissivity=0.9,
    solar_absorptivity=0.9,
    temperature1=25,
    temperature2=75,
    resistance_at_temperature1=7.283e-5,
    resistance_at_temperature2=8.688e-5,
    aluminium_cross_section_area=float("nan"),  # No core magnetisation loss
    constant_magnetic_effect=1,
    current_density_proportional_magnetic_effect=0,
    max_magnetic_core_relative_resistance_increase=1,
)


start_tower = linerate.Tower(latitude=50 - 0.0045, longitude=0, altitude=500 - 88)
end_tower = linerate.Tower(latitude=50 + 0.0045, longitude=0, altitude=500 + 88)
span = linerate.Span(
    conductor=conductor,
    start_tower=start_tower,
    end_tower=end_tower,
    ground_albedo=0.15,
    num_conductors=1,
)


weather = linerate.Weather(
    air_temperature=20,
    wind_direction=np.radians(80),  # Conductor azimuth is 0, so angle of attack is 80
    wind_speed=1.66,
    clearness_ratio=0.5,
)


time_of_measurement = np.datetime64("2016-10-03 14:00")
max_conductor_temperature = 100
current_load = 1000

model = linerate.Cigre601(span, weather, time_of_measurement)
conductor_rating = model.compute_steady_state_ampacity(max_conductor_temperature)
print(f"The span has a steady-state ampacity rating of {conductor_rating:.0f} A if the maximum temperature is {max_conductor_temperature} °C")
conductor_temperature = model.compute_conductor_temperature(current_load)
print(f"The conductor has a temperature of {conductor_temperature:.0f} °C when operated at {current_load} A")

Transient state solver

There is currently no transient solver or short time thermal rating solver, but that is on the roadmap.

Development

Dependencies for the project are managed with poetry. To install all dependencies run:

poetry install

Remember that when developing a library it is not recommended to commit the poetry.lock file.

Generate docs

To generate docs locally:

• Install required dependencies with poetry install --with docs.
• Generate docs with poetry run make html in the docs folder.

Release new version

Press the "Draft new release" button on the Releases page. Choose or create an appropriate tag, e.g. 1.2.3. Press "Generate release notes" to generate release notes. Edit Release notes if necessary and press "Publish release". This causes the publish workflow to run, which publishes the package to PyPI and generates docs on Github pages.