Add wind power potential and wind profile indicators #1471
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Hi @huard, I think overall this looks great! There is one important change due to another typo in the Tobin (2018) paper, and some suggestions for the function descriptors.
xclim/indices/_conversion.py
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| For non-standard air density (:math:`\rho`), the wind speed is scaled using | ||
| :math:`v_n = v \left( \frac{\rho}{\rho_0} \right)^{1/3}`. | ||
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| Note that the temporal resolution of the wind speed time series has a significant influence on the results, |
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Perhaps this is not necessary, but you could also note that temporal resolution may affect aggregation in time
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Changed to
Note that the temporal resolution of the wind speed time series has a significant influence on the results,
even when aggregated at longer time scales. Total annual power production will differ substantially if estimated
from hourly or daily wind speeds, due to the non-linearity of the production factor.
Is this what you meant ?
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Hi David, sorry for the long delay. I think the original wording was better. I was referring to, when summing up to create an annual power production estimate, they need to multiple by 3 if they use 3-hourly data, etc. But I'm not sure if that note is worth including.
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Sent: Monday, September 18, 2023 9:02 AM
To: Ouranosinc/xclim ***@***.***>
Cc: laura-vanvliet ***@***.***>; Comment ***@***.***>
Subject: Re: [Ouranosinc/xclim] Add wind power potential and wind profile indicators (PR #1471)
@huard commented on this pull request.
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In xclim/indices/_conversion.py<#1471 (comment)>:
+ and rated speed, is constant between the rated and cut-out speed, and is zero for wind speeds above the cut-out
+ speed to avoid damage to the turbine :cite:p:`tobin_2018`:
+
+ .. math::
+
+ \begin{cases}
+ 0, & v < u_i \\
+ (v - u_i)^3 / (u_r - u_i)^3, & u_i ≤ v < u_r \\
+ 1, & u_r ≤ v < u_o \\
+ 0, & v ≥ u_o
+ \end{cases}
+
+ For non-standard air density (:math:`\rho`), the wind speed is scaled using
+ :math:`v_n = v \left( \frac{\rho}{\rho_0} \right)^{1/3}`.
+
+ Note that the temporal resolution of the wind speed time series has a significant influence on the results,
Changed to
Note that the temporal resolution of the wind speed time series has a significant influence on the results,
even when aggregated at longer time scales. Total annual power production will differ substantially if estimated
from hourly or daily wind speeds, due to the non-linearity of the production factor.
Is this what you meant ?
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Ok, changed the wording of the docstring to simplify, and added a note explaining how to aggregate instantaneous power potential at lower frequencies. Tests have also been improved in the process, including one demoing the conversion to daily power production in MWh from 3-hourly values. Also fixed a bug in to_agg_units, but I note there are no explicit tests for this function. |
Pull Request Checklist:
number) and pull request (:pull:number) has been addedWhat kind of change does this PR introduce?
Does this PR introduce a breaking change?
No
Other information:
Ideally we`d add an indicator to compute air density, which is an optional input to the wind power potential.