Upgrade analysis¶
Upgrade analysis measures the production gain of a turbine upgrade by comparing a test group with a control group over the same months. Each group is first compared with its own expected production, so wind conditions cancel out in the difference.
Typical use: verify the gain of a manufacturer upgrade on a test group before extending it to the whole farm.
Data selection¶
Only 10-minute records in which the SCADA status of a turbine is full performance are used. This excludes stops, curtailment and out-of-environmental-spec operation, which would otherwise dominate a monthly energy total. An upgrade that changes their frequency, for example more derating after a power upgrade, must be assessed separately.
Relative difference¶
For each group, the measured energy over the selected records is summed and divided by the Tipspeed-optimized expectation for the same records:
The main result is the difference between the relative differences of the Test group and the Control group, in percentage points. Each group is first compared with its own expectation, so the effect of a windy month cancels out in the difference.
Monthly data coverage¶
A month is included only when both groups have sufficient data. The data coverage of a group is the number of its full-performance 10-minute records divided by the product of the number of 10-minute periods in the calendar month (days × 144) and the number of turbines in the group. It must reach the selected minimum.
The denominator always covers the whole calendar month, even when the selected date range covers only part of it. A partial month at either end of the range therefore falls below the threshold instead of appearing as a drop in the result.
Energy per turbine¶
Energies are shown per turbine: the total of each group is divided by the number of turbines selected in it. Groups of different sizes are therefore directly comparable.