Quality flags

Checks never change the data. Each returns one integer flag per interval; flags combine with |, so one interval can carry several.

flag	value	meaning
MISSING	1	no value recorded
STUCK	2	the same value repeated over a run of intervals (frozen sensor or logger)
OUT_OF_RANGE	4	outside the plausible range of the signal
FILLED	8	set by the analyst for values filled or corrected; never set by the checks

from res_asset_kpi import quality

flags = quality.quality_flags(frame["t_amb"], "t_amb", stuck_run=24)   # six hours of 15-minute values
quality.summary(flags)                     # intervals per flag
quality.coverage(flags, periods)           # share of usable intervals per period
t_amb = quality.apply_flags(frame["t_amb"], flags)   # rejected values set to NaN, by the analyst's decision

Stuck values. A run of at least stuck_run exactly equal values is flagged. Values whose runs are normal (0 for irradiance at night or for the power of a stopped turbine) are passed as stuck_ignore. Typical run lengths are six hours for temperatures and three 10-minute records for an anemometer above 1 m/s.

Ranges. The defaults (quality.RANGES) are wide physical limits meant to catch unit and scaling errors, for example a temperature in °F read as °C or a state of charge in percent read as a fraction. They do not judge a sensor; tighten them per site.

In the PVDAQ example the ambient temperature sensor of system 34 stays frozen for 31 511 quarter-hours (about 30 % of the three years); the flags remove those intervals from the temperature-corrected ratios instead of letting a constant 0 °F distort them.