Add example of larger floating farm with comparison to fixed-bottom. (N…

…REL#695) * Example running, less flow visualizations. * Adding top-down and side-on flow visualizations. * Add example to docs. * Trailing edge whitespace removal. * Adding some extra comments to examples docs linking floating examples. * trailing whitespace catching me out... * More trailing whitespace" * Small update to EmG viz examples to avoid warnings when calculating shear at z=0, clean up printout.
rafmudaf · Aug 15, 2023 · 8ece0f5 · 8ece0f5
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diff --git a/docs/examples.md b/docs/examples.md
@@ -110,6 +110,10 @@ of a turbine layout within FLORIS.
 Demonstrates the definition of a floating turbine and how to enable the effects of tilt
 on Cp and Ct.
 
+For further examples on floating wind turbines, see also examples
+25 (vertical wake deflection by a forced tilt angle) and 29 (comparison between
+a fixed-bottom and floating wind farm).
+
 ### 25_tilt_driven_vertical_wake_deflection.py
 
 This example demonstrates vertical wake deflections due to the tilt angle when running
@@ -118,6 +122,10 @@ vertical deflections at this time. Also be aware that this example uses a potent
 unrealistic tilt angle, 15 degrees, to highlight the wake deflection. Moreover, the magnitude
 of vertical deflections due to tilt has not been validated.
 
+For further examples on floating wind turbines, see also examples
+24 (effects of tilt on turbine power and thrust coefficients) and 29
+(comparison between a fixed-bottom and floating wind farm).
+
 ### 26_empirical_gauss_velocity_deficit_parameters.py
 
 This example illustrates the main parameters of the Empirical Gaussian
@@ -138,6 +146,18 @@ mast across all wind directions (at a fixed free stream wind speed).
 Try different values for met_mast_option to vary the location of the met mast within
 the two-turbine farm.
 
+### 29_floating_vs_fixedbottom_farm.py
+
+Compares a fixed-bottom wind farm (with a gridded layout) to a floating
+wind farm with the same layout. Includes:
+- Turbine-by-turbine power comparison for a single wind speed and direction
+- Flow visualizations for a single wind speed and direction
+- AEP calculations based on an example wind rose.
+
+For further examples on floating wind turbines, see also examples
+24 (effects of tilt on turbine power and thrust coefficients) and 25
+(vertical wake deflection by a forced tilt angle).
+
 ## Optimization
 
 These examples demonstrate use of the optimization routines

diff --git a/examples/25_tilt_driven_vertical_wake_deflection.py b/examples/25_tilt_driven_vertical_wake_deflection.py
@@ -41,7 +41,7 @@
 # Figure settings
 x_bounds = [-500, 3000]
 y_bounds = [-250, 250]
-z_bounds = [0, 500]
+z_bounds = [0.001, 500]
 
 cross_plane_locations = [10, 1200, 2500]
 horizontal_plane_location=90.0

diff --git a/examples/26_empirical_gauss_velocity_deficit_parameters.py b/examples/26_empirical_gauss_velocity_deficit_parameters.py
@@ -42,7 +42,7 @@ def generate_wake_visualization(fi: FlorisInterface, title=None):
     # Using the FlorisInterface functions, get 2D slices.
     x_bounds = [-500, 3000]
     y_bounds = [-250, 250]
-    z_bounds = [0, 500]
+    z_bounds = [0.001, 500]
     cross_plane_locations = [10, 1200, 2500]
     horizontal_plane_location = 90.0
     streamwise_plane_location = 0.0

diff --git a/examples/27_empirical_gauss_deflection_parameters.py b/examples/27_empirical_gauss_deflection_parameters.py
@@ -44,7 +44,7 @@ def generate_wake_visualization(fi, title=None):
     # Using the FlorisInterface functions, get 2D slices.
     x_bounds = [-500, 3000]
     y_bounds = [-250, 250]
-    z_bounds = [0, 500]
+    z_bounds = [0.001, 500]
     cross_plane_locations = [10, 1200, 2500]
     horizontal_plane_location = 90.0
     streamwise_plane_location = 0.0
@@ -153,8 +153,6 @@ def generate_wake_visualization(fi, title=None):
 # Increase the maximum deflection attained
 fi_dict_mod = copy.deepcopy(fi_dict)
 
-print(fi_dict_mod['wake']['wake_deflection_parameters']['empirical_gauss'])
-
 fi_dict_mod['wake']['wake_deflection_parameters']['empirical_gauss']\
     ['horizontal_deflection_gain_D'] = 5.0
 

diff --git a/examples/29_floating_vs_fixedbottom_farm.py b/examples/29_floating_vs_fixedbottom_farm.py
@@ -0,0 +1,147 @@
+# Copyright 2021 NREL
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+# See https://floris.readthedocs.io for documentation
+
+import matplotlib.pyplot as plt
+import numpy as np
+import pandas as pd
+from scipy.interpolate import NearestNDInterpolator
+
+import floris.tools.visualization as wakeviz
+from floris.tools import FlorisInterface
+
+
+"""
+This example demonstrates the impact of floating on turbine power and thurst
+and wake behavior. A floating turbine in FLORIS is defined by including a
+`floating_tilt_table` in the turbine input yaml which sets the steady tilt
+angle of the turbine based on wind speed.  This tilt angle is computed for each
+turbine based on effective velocity.  This tilt angle is then passed on
+to the respective wake model.
+
+The value of the parameter ref_tilt_cp_ct is the value of tilt at which the
+ct/cp curves have been defined.
+
+With floating_correct_cp_ct_for_tilt True, the difference between the current
+tilt as interpolated from the floating tilt table is used to scale the turbine
+power and thrust.
+
+In the example below, a 20-turbine, gridded wind farm is simulated using
+the Empirical Gaussian wake model to show the effects of floating turbines on
+both turbine power and wake development.
+
+fi_fixed: Fixed bottom turbine (no tilt variation with wind speed)
+fi_floating: Floating turbine (tilt varies with wind speed)
+"""
+
+# Declare the Floris Interface for fixed bottom, provide layout
+fi_fixed = FlorisInterface("inputs_floating/emgauss_fixed.yaml")
+fi_floating = FlorisInterface("inputs_floating/emgauss_floating.yaml")
+x, y = np.meshgrid(np.linspace(0, 4*630., 5), np.linspace(0, 3*630., 4))
+for fi in [fi_fixed, fi_floating]:
+    fi.reinitialize(layout_x=x.flatten(), layout_y=y.flatten())
+
+# Compute a single wind speed and direction, power and wakes
+for fi in [fi_fixed, fi_floating]:
+    fi.reinitialize(
+        layout_x=x.flatten(),
+        layout_y=y.flatten(),
+        wind_speeds=[10],
+        wind_directions=[270]
+    )
+    fi.calculate_wake()
+
+powers_fixed = fi_fixed.get_turbine_powers()
+powers_floating = fi_floating.get_turbine_powers()
+power_difference = powers_floating - powers_fixed
+
+# Show the power differences
+fig, ax = plt.subplots()
+ax.set_aspect('equal', adjustable='box')
+sc = ax.scatter(
+    x.flatten(),
+    y.flatten(),
+    c=power_difference.flatten()/1000,
+    cmap="PuOr",
+    vmin=-100,
+    vmax=100,
+    s=200,
+)
+ax.set_xlabel("x coordinate [m]")
+ax.set_ylabel("y coordinate [m]")
+ax.set_title("Power increase due to floating for each turbine.")
+plt.colorbar(sc, label="Increase (kW)")
+
+print("Power increase from floating over farm (10m/s, 270deg winds): {0:.2f} kW".\
+      format(power_difference.sum()/1000))
+
+# Visualize flows (see also 02_visualizations.py)
+horizontal_planes = []
+y_planes = []
+for fi in [fi_fixed, fi_floating]:
+    horizontal_planes.append(
+        fi.calculate_horizontal_plane(
+            x_resolution=200,
+            y_resolution=100,
+            height=90.0,
+        )
+    )
+    y_planes.append(
+        fi.calculate_y_plane(
+            x_resolution=200,
+            z_resolution=100,
+            crossstream_dist=0.0,
+        )
+    )
+
+# Create the plots
+fig, ax_list = plt.subplots(2, 1, figsize=(10, 8))
+ax_list = ax_list.flatten()
+wakeviz.visualize_cut_plane(horizontal_planes[0], ax=ax_list[0], title="Horizontal")
+wakeviz.visualize_cut_plane(y_planes[0], ax=ax_list[1], title="Streamwise profile")
+fig.suptitle("Fixed-bottom farm")
+
+fig, ax_list = plt.subplots(2, 1, figsize=(10, 8))
+ax_list = ax_list.flatten()
+wakeviz.visualize_cut_plane(horizontal_planes[1], ax=ax_list[0], title="Horizontal")
+wakeviz.visualize_cut_plane(y_planes[1], ax=ax_list[1], title="Streamwise profile")
+fig.suptitle("Floating farm")
+
+# Compute AEP (see 07_calc_aep_from_rose.py for details)
+df_wr = pd.read_csv("inputs/wind_rose.csv")
+wd_array = np.array(df_wr["wd"].unique(), dtype=float)
+ws_array = np.array(df_wr["ws"].unique(), dtype=float)
+
+wd_grid, ws_grid = np.meshgrid(wd_array, ws_array, indexing="ij")
+freq_interp = NearestNDInterpolator(df_wr[["wd", "ws"]], df_wr["freq_val"])
+freq = freq_interp(wd_grid, ws_grid)
+freq = freq / np.sum(freq)
+
+for fi in [fi_fixed, fi_floating]:
+    fi.reinitialize(
+        wind_directions=wd_array,
+        wind_speeds=ws_array,
+    )
+
+# Compute the AEP
+aep_fixed = fi_fixed.get_farm_AEP(freq=freq)
+aep_floating = fi_floating.get_farm_AEP(freq=freq)
+print("Farm AEP (fixed bottom): {:.3f} GWh".format(aep_fixed / 1.0e9))
+print("Farm AEP (floating): {:.3f} GWh".format(aep_floating / 1.0e9))
+print("Floating AEP increase: {0:.3f} GWh ({1:.2f}%)".\
+      format((aep_floating - aep_fixed) / 1.0e9,
+             (aep_floating - aep_fixed)/aep_fixed*100
+             )
+)
+
+plt.show()
diff --git a/examples/inputs_floating/emgauss_fixed.yaml b/examples/inputs_floating/emgauss_fixed.yaml
@@ -0,0 +1,105 @@
+
+name: Emperical Gaussian
+description: Example of single fixed-bottom turbine
+floris_version: v3.x
+
+logging:
+  console:
+    enable: true
+    level: WARNING
+  file:
+    enable: false
+    level: WARNING
+
+solver:
+  type: turbine_grid
+  turbine_grid_points: 3
+
+farm:
+  layout_x:
+  - 0.0
+  - 630.0
+  - 1260.0
+  layout_y:
+  - 0.0
+  - 0.0
+  - 0.0
+  turbine_type:
+  - !include turbine_files/nrel_5MW_fixed.yaml
+
+flow_field:
+  air_density: 1.225
+  reference_wind_height: -1 # -1 is code for use the hub height
+  turbulence_intensity: 0.06
+  wind_directions:
+  - 270.0
+  wind_shear: 0.12
+  wind_speeds:
+  - 8.0
+  wind_veer: 0.0
+
+wake:
+  model_strings:
+    combination_model: sosfs
+    deflection_model: empirical_gauss
+    turbulence_model: wake_induced_mixing
+    velocity_model: empirical_gauss
+
+  enable_secondary_steering: false
+  enable_yaw_added_recovery: true
+  enable_transverse_velocities: false
+
+  wake_deflection_parameters:
+    gauss:
+      ad: 0.0
+      alpha: 0.58
+      bd: 0.0
+      beta: 0.077
+      dm: 1.0
+      ka: 0.38
+      kb: 0.004
+    jimenez:
+      ad: 0.0
+      bd: 0.0
+      kd: 0.05
+    empirical_gauss:
+      horizontal_deflection_gain_D: 3.0
+      vertical_deflection_gain_D: -1
+      deflection_rate: 15
+      mixing_gain_deflection: 0.0
+      yaw_added_mixing_gain: 0.0
+
+  wake_velocity_parameters:
+    cc:
+      a_s: 0.179367259
+      b_s: 0.0118889215
+      c_s1: 0.0563691592
+      c_s2: 0.13290157
+      a_f: 3.11
+      b_f: -0.68
+      c_f: 2.41
+      alpha_mod: 1.0
+    gauss:
+      alpha: 0.58
+      beta: 0.077
+      ka: 0.38
+      kb: 0.004
+    jensen:
+      we: 0.05
+    empirical_gauss:
+      wake_expansion_rates:
+      - 0.01
+      - 0.005
+      breakpoints_D:
+      - 10
+      sigma_0_D: 0.28
+      smoothing_length_D: 2.0
+      mixing_gain_velocity: 2.0
+  wake_turbulence_parameters:
+    crespo_hernandez:
+      initial: 0.1
+      constant: 0.5
+      ai: 0.8
+      downstream: -0.32
+    wake_induced_mixing:
+      atmospheric_ti_gain: 0.0