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1. TECHÉOL WIND VANE ALIGNMENT
AEP Gain Estimation
Report submitted by:
Marilys Clément, M.Sc.
Nigel Swytink-Binnema, Jr. Eng., M.Sc.A.
Reviewed by:
Matthew Wadham-Gagnon, P. Eng., M.Eng.
TechnoCentre éolien
Submitted to: Techéol
March 12, 2018
T0315-05-001-RPT-E01

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TECHÉOL WIND VANE ALIGNMENT
AEP Gain Estimation 2
DISCLAIMER
The report has been prepared by TechnoCentre éolien ("TCE"). Neither the persons in the
distribution list, nor the company for which these persons work, nor any of their employees make
any warranty, expressed or implied, or assume any legal liability or responsibility for the accuracy,
completeness, or usefulness of any information, apparatus, product or process disclosed herein,
nor do they guarantee that use thereof will not infringe on privately owned rights. Reference
herein to any specific commercial product, process, or service by trademark, name, manufacturer
or otherwise does not necessarily constitute or imply endorsement, recommendation, or
favouring thereof by TCE or any business thereof. Accordingly, TCE assumes no responsibility
whatsoever for any damages or other liability (including any consequential damages) arising from
or related to the application of the information, results, findings or analysis contained in this
report.

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TECHÉOL WIND VANE ALIGNMENT
AEP Gain Estimation 3
Context
A laser alignment was performed during the months of July and August 2016 on a wind farm with
85 General Electric 1.5 MW wind turbines. The laser alignment procedure includes a calibration
tool for wind vane realignment for which Techéol has an exclusive operating license.
The TechnoCentre éolien (TCE) evaluated the performance of the laser alignment on the wind
farm and presented the results on September 19, 2017 in the report “Techéol Wind Vane
Alignment Gain Assessment” (T0278-003-RPI-E01), referred to as the Full Technical Report.
Presented herein is a new extrapolation approach for the calculation of the AEP gain associated
with the wind vane alignment at the wind farm.
Summary of Full Technical Report
This section summarizes the methodology (Section 5) and results (Section 9) from the Full
Technical Report. First, the analysis was split into the two periods presented in Table 1.
Table 1: Analysis Periods
Period Start Date End Date
Pre-alignment 2016-01-01 2016-07-01
Post-alignment 2016-09-01 2016-12-15
Next, the turbines were separated into three groups based on their initial misalignment angle
(Table 2).
Table 2: Turbine Misalignment Groups
Group
Misalignment
Angle
Total
Turbines
Studied
Turbines
Group R -1° to 1° 29 22
Group 1 1° to 5° 44 14
Group 2 5° + 10 3
Rejected < -1° 2 0
Following that, some turbines were excluded based on criteria such as low availability, high error
rate, use of low-noise operation, etc., as presented in the final column of Table 2 (see Table ix in
First Report for complete list and details). The remaining turbines’ data were filtered: periods of
downtime and data outside normal turbine operation thresholds were excluded (see Table x in
First Report for complete list and details).
To assess the gain attributable to alignment, turbine pairs were created between reference
turbines (Group R) and studied turbines (Group 1 and Group 2) located in a same geographic zone
of the wind farm (see last column of Table 2). Simultaneous filters were applied for each pair: any
rejected timestamp of one turbine, including operation in the wake of another turbine, was

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TECHÉOL WIND VANE ALIGNMENT
AEP Gain Estimation 4
rejected for both turbines. This ensured that all timestamps corresponded to data where both
turbines were operating in a comparable manner. Only fourteen Group 1 turbines and three
Group 2 turbines could be compared to a reference turbine with sufficient available data.
A power correlation was created for each pair with the post-alignment data (period presented in
Table 1). The post-alignment period was used because the two turbines were expected to produce
similarly since they had the same alignment. The power correlation obtained was then applied to
the studied turbine’s pre-alignment data to simulate its power production as if it had been
correctly aligned (as the reference turbine is assumed to be).
For the pre-alignment period, the actual production was subtracted from the simulated
production and divided by the actual production, providing the simulated gain as a percentage
(see first line of Table 3). This shows how the wind vane misalignment has influenced the power
production of the studied turbines and how much energy would have been gained had it been
correctly aligned during simultaneously available pre-alignment periods.
Extrapolation to Annual Energy and Results
To estimate the wind farm’s AEP gain for 2016, the gain obtained from the Full Technical Report
was extrapolated to: 1) the whole year, and then 2) the whole wind farm. Turbines misaligned by
less than 5° (Group 1) did not show any measurable gain; results are only presented for turbines
misaligned by more than 5° (Group 2).
First, it was assumed that the gain achieved during the simulation period for Group 2 turbines
would be the same for the whole year. That assumption was based on the hypothesis that the
gain due to realignment remains the same despite wake effects and seasonal variations in wind
speed or direction. Hence the gain should be the same during all periods. Therefore, the average
AEP gain for the three studied turbines misaligned by more than 5° (Group 2) ranged from 3.6%
to 9.7% with an average of 6.7% (first line of Table 3).
Second, by assuming all ten Group 2 turbines in the wind farm experienced the same gains, and
all other turbines (Group R and Group 1) experienced no gains, it was estimated that the turbine
realignment generated an AEP gain of 0.8% (second line of Table 3).
Table 3: Extrapolated Energy Gain
Results for: Results Based on: Min Gain Max Gain Average Gain
Single turbine misaligned
by >5°
Three Group 2
turbines
3.6% 9.7% 6.7%
Wind farm with 12%
turbines misaligned by >5°
Extrapolation to
wind farm
0.43% 1.16% 0.80%