to_powerdata returns bus va in degrees while its docstring says angles are radians #138

to_powerdata's docstring states:

Powers are per unit on baseMVA, angles are radians, bus_i keeps the source bus id [...]

The branch rows honour that — src/exa.jl converts phase_shift_degrees, angle_min_degrees and angle_max_degrees with deg2rad. The bus rows do not:

va = _finite(b.va_degrees, T, label, :va),

so bus.va reaches the caller in degrees while branch.shift, branch.angmin and branch.angmax reach it in radians, out of the same call.

A consumer that trusts the docstring and uses bus.va as a warm start, or compares it against branch.shift, is silently off by 180/pi. It is invisible on a flat start, where every va is zero, which is most test cases.

Expected: va = deg2rad(_finite(b.va_degrees, ...)), matching the branch rows and the docstring. Alternatively rename the field so the unit is stated, but the docstring promise is the simpler thing to keep.

This is a behaviour change for anyone already compensating, so it probably wants a CHANGELOG note.

Found while porting PowerDiff.jl to 0.11 (grid-opt-alg-lab/PowerDiff.jl#76). PowerDiff does not consume bus.va, so it is unaffected either way.