Multi-height wind data¶
In this example we explore the calculation of multi-height wind data, as for example obtained from WRF results or downloaded from the NEWA website at a single point.
Here we will use the static data file WRF-Timeseries-3000.nc that is part of the foxes static data. The time coordinate marks one month in 10 minute steps, and the wind speed (WS), wind direction (WD) and turbulent intensity (TI) are provided at 8 heights between 50 and 500 m. The air density (RHO) does not have height dependency but varies with time. The detailed data structure will be displayed below.
The basic assumption of this example is that we can calculate our wind farm results based on this data, i.e., that the horizontal variation can be neglected (for completely heterogeneous inflow data, see the corresponding example).
These are the imports for this example:
In [1]:
%matplotlib inline
import matplotlib.pyplot as plt
from xarray import open_dataset
import foxes
import foxes.variables as FV
First, we setup the model book and the wind farm. We choose 5 turbines in a row:
In [2]:
# create wind farm, a single row of turbines:
farm = foxes.WindFarm()
foxes.input.farm_layout.add_row(
farm=farm,
xy_base=[0.0, 0.0],
xy_step=[600.0, 0.0],
n_turbines=5,
turbine_models=["NREL5MW"],
H=200.0,
verbosity=0,
)
ax = foxes.output.FarmLayoutOutput(farm).get_figure(figsize=(5, 3))
plt.show()
Note that we manually change the hub height from 90 m to 200 m here. Next, we create the states based on the static data file WRF-Timeseries-3000.nc:
In [3]:
# This is what the nc file looks like:
fpath = foxes.StaticData().get_file_path(foxes.STATES, "WRF-Timeseries-3000.nc")
open_dataset(fpath)
Out[3]:
<xarray.Dataset> Size: 528kB
Dimensions: (Time: 3000, height: 8)
Coordinates:
* Time (Time) <U19 228kB '2009-01-01 00:00:00' ... '2009-01-21 19:50:00'
* height (height) float32 32B 50.0 75.0 90.0 100.0 150.0 200.0 250.0 500.0
Data variables:
ws (Time, height) float32 96kB ...
wd (Time, height) float32 96kB ...
ti (Time, height) float32 96kB ...
rho (Time) float32 12kB ...Now let’s create the corresponding states object:
In [4]:
states = foxes.input.states.MultiHeightNCTimeseries(
data_source="WRF-Timeseries-3000.nc",
time_coord="Time",
h_coord="height",
output_vars=[FV.WS, FV.WD, FV.TI, FV.RHO],
var2col={FV.WS: "ws", FV.WD: "wd", FV.TI: "ti", FV.RHO: "rho"},
)
o = foxes.output.StatesRosePlotOutput(states, point=[0.0, 0.0, 100.0])
o.get_figure(16, FV.AMB_WS, [0, 3.5, 6, 10, 15, 20], figsize=(6, 6))
plt.show()
Selecting 'DefaultEngine(n_procs=16, chunk_size_states=None, chunk_size_points=None)'
DefaultEngine: Selecting engine 'single'
SingleChunkEngine: Calculating 3000 states for 1 turbines
SingleChunkEngine: Running single chunk calculation for 3000 states
Note how the var2col option offers a mapping from the expected to the actual column names, if needed.
Let’s next setup our algorithm. Notice that we include the z-sensitive rotor model level10, with 10 points on a vertical line (also the grid models would be an option). The partial wakes choice None represents default settings for all wake models. It is important that we do not select rotor_points together with the level10 rotor, since averaging over a vertical line of points does not make much sense.
In [5]:
algo = foxes.algorithms.Downwind(
farm,
states,
rotor_model="level10",
wake_models=["Bastankhah2014_linear_ka02"],
partial_wakes=None,
verbosity=0,
)
We now visualize the vertical flow profile. Alternatively to the here shown use of the states_sel parameter in the plotting function, we could have reduced the whole states object by states.reset(states_loc=["2009-01-06 13:50:00"]).
In [6]:
farm_results = algo.calc_farm()
o = foxes.output.FlowPlots2D(algo, farm_results)
g = o.gen_states_fig_xz(
FV.AMB_WS,
resolution=10,
x_direction=270,
xmin=0.0,
xmax=1000.0,
zmin=50.0,
zmax=500.0,
figsize=(8, 6),
states_sel=["2009-01-06 13:50:00"],
)
fig = next(g)
plt.show()
DefaultEngine: Selecting engine 'single'
SingleChunkEngine: Calculating 3000 states for 5 turbines
SingleChunkEngine: Running single chunk calculation for 3000 states
States 'MultiHeightNCTimeseries': Reading file /home/jonas/gits/wakes/foxes/foxes/data/states/WRF-Timeseries-3000.nc
DefaultEngine: Selecting engine 'process'
ProcessEngine: Calculating data at 4646 points for 1 states
ProcessEngine: Computing 16 chunks using 16 processes
100%|███████████████████████████████████████████████████████████████████████████████████| 16/16 [00:00<00:00, 46.67it/s]
We can now calculate the full states results:
In [7]:
farm_results = algo.calc_farm()
fr = farm_results.to_dataframe()
print(fr[[FV.WD, FV.REWS, FV.P]])
o = foxes.output.FarmLayoutOutput(farm, farm_results)
o.get_figure(color_by="mean_REWS", title="Mean REWS [m/s]", s=150, annotate=0)
plt.show()
o = foxes.output.FarmResultsEval(farm_results)
P0 = o.calc_mean_farm_power(ambient=True)
P = o.calc_mean_farm_power()
print(f"\nFarm power : {P/1000:.1f} MW")
print(f"Farm ambient power: {P0/1000:.1f} MW")
print(f"Farm efficiency : {o.calc_farm_efficiency()*100:.2f} %")
print(f"Annual farm yield : {o.calc_farm_yield(algo=algo):.2f} GWh")
DefaultEngine: Selecting engine 'single'
SingleChunkEngine: Calculating 3000 states for 5 turbines
SingleChunkEngine: Running single chunk calculation for 3000 states
WD REWS P
state turbine
2009-01-01 00:00:00 0 340.149890 7.593225 1460.198707
1 340.149890 7.593225 1460.198707
2 340.149890 7.593225 1460.198707
3 340.149890 7.593225 1460.198707
4 340.149890 7.593225 1460.198707
... ... ... ...
2009-01-21 19:50:00 0 201.692583 7.628299 1512.458987
1 201.692583 7.628299 1512.458987
2 201.692583 7.628299 1512.458987
3 201.692583 7.628299 1512.458987
4 201.692583 7.628299 1512.458987
[15000 rows x 3 columns]
Farm power : 14.8 MW
Farm ambient power: 15.2 MW
Farm efficiency : 97.27 %
Annual farm yield : 129.93 GWh
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