Environmental curtailment¶
A curtailment plan reduces the output of a turbine under set conditions: at night for noise, at low wind speed in the bat season, in some wind directions to limit wake loads. Tipspeed reads each plan and checks whether it is applied as written, as often as the digital twin predicts, and at the cost it predicts.
Typical use: find a plan that is not applied as written, or a curtailment that costs more energy than expected.
Curtailment plans¶
A plan states when it applies (a time of day, a season, a wind speed, a wind direction, a temperature) and the operating mode the turbine runs in while it applies. An operating mode is one of the power curves of the turbine model: a reduced mode produces less than the normal mode at the same wind speed, or stops the turbine.
Tipspeed groups plans by category: noise, bat, wind sector management, turbulence and shadow flicker. When several plans apply at the same time on one turbine, the plan listed last in the turbine's set-up sets the mode and its category.
Operating modes¶
Each turbine and 10-minute record carries an operating mode, named after the mode number and the category of the plan
that commands it: mode_0 for the normal mode, mode_1_noise for mode 1 under a noise plan, stopped_bat for a stop
under a bat plan.
- Expected mode (based on SCADA): the mode the plans command, evaluated on the turbine's own measurements.
- Expected mode (model prediction): the same plans evaluated on the wind of the Tipspeed digital twin.
- Actual mode: the mode the turbine's signals show (rotor speed, power, pitch), detected without reading the plan. It is not detected where the signals cannot tell the modes apart, which covers most low-wind records.
A stop while a plan applies counts as a curtailment of that plan's category (stopped_bat during a bat plan), whatever
mode the plan commands. A stop while no plan applies counts as availability, not curtailment.
Curtailment in the energy waterfall¶
A record on which a curtailment mode is detected is not counted as full performance: its production is replaced by the production the turbine would have had in its normal mode, and the difference is part of the partial-performance loss of the energy waterfall. A stop under a plan stays in the stopped loss. The digital twin reports the curtailment loss it predicts for each category, which the recoverable energy compares with an optimised operation.
Checks¶
| Check | Actual | Expected |
|---|---|---|
| Plan compliance | Actual hours: hours the turbines are detected in a curtailment mode | Expected hours (based on SCADA): hours the plans command, evaluated on the SCADA |
| Trigger accuracy | Expected hours (based on SCADA) | Expected hours (model prediction): hours the plans command on the digital twin's wind |
| Gap vs. expected | Actual loss: actual production loss on records detected in a curtailment mode | Expected loss (model prediction): the curtailment loss of the digital twin |