feat: pandapower comparison tests and sensitivity analysis

.github/workflows/ci.yml

@@ -15,6 +15,7 @@ jobs:
           enable-cache: true
       - run: uv sync --frozen
       - run: uv run ruff check . --verbose
+      - run: uv run ruff format --check .
 
   test:
     runs-on: ubuntu-latest

research/pandapower/02_nopywer_power_calculations.md

@@ -14,7 +14,7 @@ form factors (16 A / 32 A / 63 A / 125 A).
 A GeoJSON FeatureCollection containing:
 
 - **Point features** → loads or the generator. Properties: `name`, `power`
-  (watts), `phase` (1, 2, 3, "U", "Y", or null). The generator is identified
+  (watts), `phase` (1, 2, 3, or null). The generator is identified
   by the substring `"generator"` in its name.
 - **LineString features** → cables with the two coordinate endpoints.
   Properties: `length` (m, optional — geodesic distance is used otherwise),

research/pandapower/03_intersection.md

@@ -7,7 +7,7 @@ nopywer concepts have a direct pandapower analogue and which do not.
 
 | nopywer concept | pandapower analogue | Notes / friction |
 |---|---|---|
-| `PowerNode` (load) | `net.load` (balanced) or `net.asymmetric_load` (per-phase) | Loads with `phase ∈ {1,2,3}` would need `asymmetric_load` with `p_a_mw / p_b_mw / p_c_mw`. nopywer's "U" / "Y" sub-grid markers have no pandapower analogue. |
+| `PowerNode` (load) | `net.load` (balanced) or `net.asymmetric_load` (per-phase) | Loads with `phase ∈ {1,2,3}` would need `asymmetric_load` with `p_a_mw / p_b_mw / p_c_mw`. Non-numeric or missing phase data has no pandapower analogue and should be treated as unassigned. |
 | `PowerNode` (generator) | `net.ext_grid` (slack bus) | Pandapower needs a slack reference. The generator has no internal impedance in nopywer — would map to a `vm_pu = 1.0` `ext_grid` on a dedicated bus. |
 | `Cable` | `net.line` | The bridge requires R, X, C, max-I per km — see "Cable model gap" below. |
 | `Cable.length_m` | `line.length_km` | Straight conversion `× 1e-3`. Pandapower forbids zero-length lines. |

research/pandapower/04_porting_considerations.md

@@ -109,11 +109,10 @@ These apply regardless of strategy.
   no upstream traceable source ("Rich's old notes"). Whatever path is
   chosen, this number must be carried forward visibly, with a comment, or
   explicitly retired with a justified replacement.
-- **The "phase" property.** nopywer accepts `phase ∈ {1, 2, 3, "U", "Y",
-  None}`. Phases 1/2/3 map to pandapower's a/b/c. "U" / "Y" are sub-grid
-  labels with no electrical meaning in `analyze.py` (they appear only in
-  the reporting in `print_grid_info`). They have no pandapower equivalent
-  and would need to be threaded around any pandapower path.
+- **The "phase" property.** nopywer accepts numeric phase assignments for
+  single-phase loads. Phases 1/2/3 map to pandapower's a/b/c. Missing or
+  non-numeric phase values have no pandapower equivalent and should be
+  treated as unassigned on any pandapower path.
 - **Performance and packaging.** pandapower with numba is not pip-friendly
   on every platform (Apple Silicon, NixOS, Alpine). Without numba it is
   slower but portable. For a CLI that may run on a laptop in a field,