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A normal behaviour model learns how a healthy turbine relates wind, power, temperatures and commands. When the turbine stops behaving that way, the gap between what the model expects and what the turbine reports grows, and an adaptive threshold decides when that gap is a fault rather than noise. No fault labels are needed for training.

We use quantum machine learning for the normal behaviour model. Variational quantum circuits embedded in the LSTM gates (QLSTM) capture high-order interactions among SCADA variables in Hilbert space with few parameters, and the number of input variables sets the number of qubits.

QLSTM normal behaviour model

Zhang & Ma, ICAC 2025. Gearbox bearing temperature on a fault-free test set; faults flagged by a T-distribution residual threshold.

0.9446QLSTM R²
LSTM 0.9358
1.931QLSTM RMSE
LSTM 2.278
7.67 hearlier detection of the gearbox bearing fault than LSTM

QLSTM-Transformer with BISW thresholding

Zhang et al., Energy Conversion and Management: X, 2026. Three real faults: gearbox bearing overheating, generator winding overheating and pitch control failure. BISW combines Bayesian inference with a sliding window so the threshold follows both short-term variation and long-term trend in the residual.

123.8 hwarning before shutdown
gearbox bearing
77.5 hwarning before shutdown
generator winding
122.7 hwarning before shutdown
pitch control
0false alarms
on all three faults
Normal behaviour modelling accuracy on fault-free test data
ModelGearboxGeneratorPitch
R²RMSER²RMSER²RMSE
QLSTM-Transformer0.95751.1280.95181.0760.97910.327
LSTM-Transformer0.94681.3900.94971.1270.96750.368
LSTM0.93771.4600.92432.6980.95160.420
Transformer0.93751.6290.90413.5100.95340.416
Hours of warning before turbine shutdown (BISW thresholding)
ModelGearbox bearingGenerator windingPitch control
HoursFalse alarmHoursFalse alarmHoursFalse alarm
QLSTM-Transformer123.83No77.50No122.67No
LSTM-Transformer109.67No75.50No68.83No
LSTM92.33Yes32.50No121.00No
Transformer109.67Yes76.83No120.83No

The paper also compares KDE and EWMA thresholds and the DIV and TSDT methods. QLSTM-Transformer-BISW gives the longest (or joint-longest) warning on all three faults while raising no false alarms.

Detection on the three faults

Residual indicator crossing the adaptive threshold before the gearbox bearing fault
Gearbox bearing. The residual first crosses the BISW threshold at sample 1770; the alarm log records the fault at sample 2513.
Residual indicator crossing the adaptive threshold before the generator winding fault
Generator winding. First detection at sample 1220, against the alarm-log fault at sample 1685.
Residual indicator crossing the adaptive threshold before the pitch control fault
Pitch control. Residual indicator and adaptive threshold ahead of the recorded pitch system fault.
Measured and QLSTM-Transformer predicted temperature on the test set
Normal behaviour model. Measured temperature against the QLSTM-Transformer prediction on the test set.

At fleet scale

In TurbineCore, a world model trained on confirmed-healthy periods plays the role of the normal behaviour model across whole wind farms, and its residual is the anomaly score.

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