groundinsight 0.3.0

Simulation for grounding systems of electrical power grids

groundinsight

Simulation of grounding systems in electrical power grids.

groundinsight is an open-source Python package for analysing the behaviour of networked grounding systems during single-phase-to-ground faults. It computes the earth-potential rise (EPR), branch (shield) currents, reduction factors and the resulting grounding impedance at the fault location for arbitrary bus/branch topologies including line, ring and mesh networks.

• Documentation: https://ce1ectric.github.io/groundinsight/
• Source: https://github.com/Ce1ectric/groundinsight
• Issue tracker: https://github.com/Ce1ectric/groundinsight/issues

Why groundinsight

Medium-voltage distribution networks are meshed through shared grounding conductors (cable shields, overhead-line earth wires, substation grounding grids). During a single-phase-to-ground fault, the return current splits between the local earth path at the fault location and the metallic return path through the grounding conductors of the surrounding branches. To assess touch-voltage safety and EMC effects, two quantities have to be known:

• the reduction factor $r$ describing the fraction of the fault current that returns through earth, and
• the grounding impedance $Z_G$ and the resulting EPR at the fault bus.

groundinsight computes both by assembling a nodal-admittance model from user-defined frequency- and $\rho_E$-dependent impedance formulas and solving it for every harmonic of interest.

Features

• Bus, branch, source and fault objects modelled as Pydantic v2 classes.
• Symbolic impedance formulas in rho, f and l, evaluated through SymPy.
• Sparse LU solver per frequency (scipy.sparse.linalg.splu).
• Mutual coupling between faulted phase and grounding conductor treated as Norton equivalents along the path from source to fault.
• Reduction factor computed from the ratio of EPR with and without mutual coupling at the fault bus.
• Support for ring and mesh grounding topologies with multiple parallel paths; the optional auto_parallel_coefficients=True flag on run_fault derives the per-path current share from a reduced phase-only solve.
• SQLite persistence and JSON export/import of networks and type libraries.
• Polars DataFrames for result access (net.res_buses(...), net.res_branches(...), net.res_all_impedances()).
• Matplotlib helpers for bar plots of EPR, branch currents and bus currents.

Installation

groundinsight requires Python 3.12 or newer and is published on PyPI:

pip install groundinsight

For a local development checkout with the test suite enabled:

git clone https://github.com/Ce1ectric/groundinsight.git
cd groundinsight
poetry install

The documentation extras live in an optional Poetry group:

poetry install --with docs

See the installation page of the documentation for full details.

Quickstart

import groundinsight as gi

net = gi.create_network(name="QuickstartNet", frequencies=[50, 250, 350])

bus_type = gi.BusType(
    name="SubstationBus",
    description="Lumped substation grounding grid",
    system_type="Substation",
    voltage_level=20,
    impedance_formula="rho * 0.01 + j * f * 1/50 * 0.1",
)

cable_type = gi.BranchType(
    name="MSCable",
    description="20 kV single-core cable with shield",
    grounding_conductor=True,
    self_impedance_formula="(0.25 + j * f * 0.012) * l",
    mutual_impedance_formula="(0.0  + j * f * 0.012) * l",
)

gi.create_bus(name="bus_source", type=bus_type, network=net, specific_earth_resistance=100.0)
gi.create_bus(name="bus_fault",  type=bus_type, network=net, specific_earth_resistance=100.0)

gi.create_branch(
    name="cable_1", type=cable_type,
    from_bus="bus_source", to_bus="bus_fault",
    length=5.0, specific_earth_resistance=100.0, network=net,
)

gi.create_source(
    name="infeed", bus="bus_source",
    values={50: 1000.0, 250: 200.0, 350: 100.0}, network=net,
)
gi.create_fault(
    name="fault1", bus="bus_fault",
    description="single-phase-to-ground fault",
    scalings={50: 1.0}, network=net,
)

gi.run_fault(network=net, fault_name="fault1")

print(net.res_all_impedances())

For a ring/meshed network, enable the automatic parallel-path distribution:

gi.run_fault(
    network=net,
    fault_name="fault1",
    auto_parallel_coefficients=True,
)

More worked examples — including the CIRED reference and a low-voltage network — are available as notebooks in the documentation.

Model overview

All computations happen per frequency $f$ in the phasor domain:

$$ Y(f),\underline{u}(f) = \underline{i}(f) \quad\Longrightarrow\quad \underline{u}(f) = Y(f)^{-1},\underline{i}(f) $$

where $Y$ is the nodal admittance matrix (bus grounding admittances on the diagonal, branch self-admittances off-diagonal), $\underline{u}$ is the EPR vector and $\underline{i}$ combines source currents and the Norton equivalents of the phase-to-shield mutual coupling. The reduction factor at the fault bus is obtained by re-solving the same system with all mutual Norton sources removed and taking the ratio $|u_{\text{fault}}^{\text{with}}|/|u_{\text{fault}}^{\text{without}}|$.

For the full model — objects, path finding, reduction factor and grounding impedance — see the Concepts page of the documentation.

Workflow

---
title: Main concept of groundinsight
---
flowchart TD
    start((Start))
    finish((End))
    net[Create a Network]
    types[Define BusType and BranchType]
    buses[Add Buses and Branches]
    source[Add Sources and Faults]
    db[(SQLite / JSON)]
    run[run_fault]
    analyze[Analyse results as DataFrames or plots]
    start --> net
    net --> types
    types --> buses
    buses --> source
    source --> run
    run --> analyze
    run --> db
    db --> finish
    analyze --> finish

Development

# run the test suite with coverage
poetry run pytest --cov=groundinsight

# format the code with black
poetry run black src tests scripts

# build the docs locally
poetry install --with docs
poetry run mkdocs serve

A release is cut via the built-in Poetry script, which bumps the version in pyproject.toml, src/groundinsight/__init__.py and CITATION.cff, creates an annotated tag and pushes the commit plus the tag. The GitHub Actions release workflow then takes over, builds sdist and wheel and publishes to PyPI via OIDC Trusted Publishing.

poetry run release patch
poetry run release minor
poetry run release major
poetry run release set 1.2.3

Citation

If you use groundinsight for scientific work, please cite it using the CITATION.cff metadata shipped with this repository.

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. New code should come with tests; please run the full suite and check that coverage does not regress.

License

groundinsight is released under the MIT License.