gridstate 0.2.0

Power system State Estimation: pure-Python WLS/IPM on numpy/scipy, input via a versioned file contract (npz).

gridstate

Power-system State Estimation in pure Python.

gridstate reconstructs the most likely operating state of an electrical network from SCADA telemetry and a topology model: voltage magnitudes and angles at every bus, plus the derived quantities — branch power flows, currents and nodal injections.

The estimator is implemented on top of numpy and scipy only — there are no proprietary or vendor dependencies. Input and output cross a single, explicit, versioned data contract (a .npz file), so the package is fully self-contained and decoupled from any particular network-model format.

 measurements (value + σ)        ┌──────────────────────┐        V, δ  (state)
 topology, impedances, taps  ──► │  gridstate.run_se    │ ──►   P, Q, I (branches)
 (SEInput, .npz contract)        │  WLS / IPM estimator │        injections, residuals
                                 └──────────────────────┘        (SEOutput contract)

Status

Pre-alpha. The core pipeline runs end to end:

• p.u. conversion of the working model (gridstate.units);
• bus-admittance assembly Ybus / Yf / Yt (gridstate.ybus);
• measurement vector z, weights R, measurement index (gridstate.z_vector);
• WLS Gauss–Newton solve — measurement function h(E), Jacobian H = ∂h/∂E, step ΔE = (HᵀR⁻¹H)⁻¹HᵀR⁻¹r (gridstate.algebra, gridstate.algorithms.wls), with SHGM-IRLS robust re-weighting;
• IPM interior-point estimator as an alternative solver;
• result write-back (V, δ, branch P/Q, currents, injections) into the output contract;
• validation: χ² test (gridstate.validation.chi2_test), bad-data removal by normalized residuals / rn_max (gridstate.validation.bad_data), observability analysis (gridstate.validation.observability).

Tests: 445 passing on Python 3.10–3.12, dependency-free (numpy/scipy only).

Installation

python -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"

Runtime dependencies are just numpy>=1.24 and scipy>=1.10. Python 3.10+.

Quick start

The public boundary is a .npz data-contract file. Load it, run the estimator, read the results:

from gridstate import load_se_input_npz, run_se

# 1. Load a state-estimation input contract (working model + precomputed plans).
se_input = load_se_input_npz("path/to/case.npz")

# 2. Run the estimator (WLS by default; production pipeline defaults applied).
out = run_se(se_input)

print(out.success, out.iterations, out.objective_value)

# 3. Read per-object results from the output contract.
bus = out.node(node_id=1001)        # {'voltage_magnitude': ..., 'voltage_angle': ..., ...}
flow = out.branch(branch_id=42)     # {'power_from_p': ..., 'current_from': ..., ...}

run_se returns an SEOutput: structured arrays nodes / branches / measurements (id + result columns) plus convergence scalars (success, iterations, objective_value, algorithm) and the state vectors v_pu / delta_rad.

To estimate from a model you already hold in memory, wrap it with load_se_input(model) (skips the format-dependent input stages) or call the lower-level estimate(model, algorithm="wls", ...) directly.

Data contract

Input and output are governed by an explicit, versioned schema (gridstate.contract):

• SE_INPUT / SE_OUTPUT — table/column declarations with roles (INPUT / WORKING / OUTPUT) for nodes, branches, measurements, generators, and the raw side tables.
• CONTRACT_VERSION follows SemVer; is_data_compatible(...) gates whether a given .npz can be consumed.
• load_se_input_npz / save_se_input round-trip the contract to disk.
• validate_input(...) checks a model against the contract and fails early on missing required columns or an incompatible version.

This contract is what lets gridstate stand alone: the estimator never depends on a concrete external network-model class — only on the data it declares it needs.

Validation

from gridstate import chi2_analysis, remove_bad_data, analyze_observability

report = analyze_observability(se_input.model)
assert report.is_observable, report.diagnostics

chi2 = chi2_analysis(se_input.model, chi2_prob_false=0.05)
if chi2.bad_data_present:
    cleaned = remove_bad_data(se_input.model, rn_max_threshold=3.0)
    print("removed measurements:", cleaned.removed_meas_ids)

Public API

Exported from the top-level package:

Symbol	Purpose
run_se, run_pipeline	run the estimation pipeline (contract / direct)
estimate	low-level single-solve entry point
load_se_input_npz, load_se_input, save_se_input	data-contract I/O
SEInput, SEOutput, SEResult	input / output / detailed result objects
PipelineConfig, pipeline_manifest	pipeline configuration & step manifest
chi2_analysis, remove_bad_data, analyze_observability	validation

Development

make install-dev    # editable install + dev/test extras + pre-commit hooks
make test           # pytest tests/
make lint           # ruff check + ruff format --check
make type-check     # mypy gridstate
make check          # format + lint + type-check + test

Continuous integration (lint, the 3.10–3.12 test matrix, and a build) runs on GitHub Actions; see .github/workflows/.

License

gridstate is released under the MIT License — see LICENSE.

The estimation core (WLS/IPM linear algebra, χ² test and bad-data detection) is adapted from pandapower, which is distributed under the BSD 3-Clause License. The full third-party notice and the list of adapted files are reproduced in the "Third-Party Software Notices" section of LICENSE.