Add function to initilize wind_turbines with one or multiple .wtg files....

Add function to initilize wind_turbines with one or multiple .wtg files. Requires using xml.etree.ElementTree, since .wtg file is stored in essence of .xml format.

py_wake/examples/data/NEG-Micon-2750.wtg

+<?xml version="1.0" encoding="UTF-8"?>
+<WindTurbineGenerator FormatVersion="1.01" Description="NEG-Micon 2750/92 (2750 kW)" ManufacturerName="" ReferenceURI="" RotorDiameter="92"><Comments></Comments><SuggestedHeights><Height>70.0</Height></SuggestedHeights><PerformanceTable AirDensity="1.225" MaximumNoiseLevel="0.0" DataStatus="Unknown" DataSource="Unknown" ReleaseDate="1899-12-30" ReferenceURI="None" StationaryThrustCoEfficient="0.059"><StartStopStrategy LowSpeedCutOut="4.0" LowSpeedCutIn="4.0" HighSpeedCutIn="25.0" HighSpeedCutOut="25.0"/><Comments></Comments><DataTable><DataPoint WindSpeed="4.0" PowerOutput="55000.0" ThrustCoEfficient="0.871"/><DataPoint WindSpeed="5.0" PowerOutput="185000.0" ThrustCoEfficient="0.853"/><DataPoint WindSpeed="6.0" PowerOutput="369000.0" ThrustCoEfficient="0.841"/><DataPoint WindSpeed="7.0" PowerOutput="619000.0" ThrustCoEfficient="0.841"/><DataPoint WindSpeed="8.0" PowerOutput="941000.0" ThrustCoEfficient="0.833"/><DataPoint WindSpeed="9.0" PowerOutput="1326000.0" ThrustCoEfficient="0.797"/><DataPoint WindSpeed="10.0" PowerOutput="1741000.0" ThrustCoEfficient="0.743"/><DataPoint WindSpeed="11.0" PowerOutput="2133000.0" ThrustCoEfficient="0.635"/><DataPoint WindSpeed="12.0" PowerOutput="2436000.0" ThrustCoEfficient="0.543"/><DataPoint WindSpeed="13.0" PowerOutput="2617000.0" ThrustCoEfficient="0.424"/><DataPoint WindSpeed="14.0" PowerOutput="2702000.0" ThrustCoEfficient="0.324"/><DataPoint WindSpeed="15.0" PowerOutput="2734000.0" ThrustCoEfficient="0.258"/><DataPoint WindSpeed="16.0" PowerOutput="2744000.0" ThrustCoEfficient="0.21"/><DataPoint WindSpeed="17.0" PowerOutput="2747000.0" ThrustCoEfficient="0.175"/><DataPoint WindSpeed="18.0" PowerOutput="2748000.0" ThrustCoEfficient="0.147"/><DataPoint WindSpeed="19.0" PowerOutput="2748000.0" ThrustCoEfficient="0.126"/><DataPoint WindSpeed="20.0" PowerOutput="2750000.0" ThrustCoEfficient="0.109"/><DataPoint WindSpeed="21.0" PowerOutput="2750000.0" ThrustCoEfficient="0.095"/><DataPoint WindSpeed="22.0" PowerOutput="2750000.0" ThrustCoEfficient="0.083"/><DataPoint WindSpeed="23.0" PowerOutput="2750000.0" ThrustCoEfficient="0.074"/><DataPoint WindSpeed="24.0" PowerOutput="2750000.0" ThrustCoEfficient="0.065"/><DataPoint WindSpeed="25.0" PowerOutput="2750000.0" ThrustCoEfficient="0.059"/></DataTable></PerformanceTable></WindTurbineGenerator>

py_wake/examples/data/Vestas-V80.wtg

+<WindTurbineGenerator FormatVersion="1.01" Description="Vestas V80 (2MW, Offshore)" ManufacturerName="Vestas Wind Systems A/S" ReferenceURI="www.vestas.dk" RotorDiameter="80"><Comments>Address: Smed Sørensens Vej 5|Address: DK-6950 Ringkøbing, Denmark|Phone: +45 96 75 25 75|Fax: +45 96 75 24 36|E-mail: vestas@vestas.dk</Comments><SuggestedHeights><Height>67.0</Height></SuggestedHeights><PerformanceTable AirDensity="1.225" DataStatus="Unknown" DataSource="" ReferenceURI="None" StationaryThrustCoEfficient="0.052"><StartStopStrategy LowSpeedCutOut="4.0" LowSpeedCutIn="4.0" HighSpeedCutIn="25.0" HighSpeedCutOut="25.0"/><Comments>Noise level 106.4 dB(A)</Comments><DataTable><DataPoint WindSpeed="4.0" PowerOutput="66600.0" ThrustCoEfficient="0.818"/><DataPoint WindSpeed="5.0" PowerOutput="154000.0" ThrustCoEfficient="0.806"/><DataPoint WindSpeed="6.0" PowerOutput="282000.0" ThrustCoEfficient="0.804"/><DataPoint WindSpeed="7.0" PowerOutput="460000.0" ThrustCoEfficient="0.805"/><DataPoint WindSpeed="8.0" PowerOutput="696000.0" ThrustCoEfficient="0.806"/><DataPoint WindSpeed="9.0" PowerOutput="996000.0" ThrustCoEfficient="0.807"/><DataPoint WindSpeed="10.0" PowerOutput="1341000.0" ThrustCoEfficient="0.793"/><DataPoint WindSpeed="11.0" PowerOutput="1661000.0" ThrustCoEfficient="0.739"/><DataPoint WindSpeed="12.0" PowerOutput="1866000.0" ThrustCoEfficient="0.709"/><DataPoint WindSpeed="13.0" PowerOutput="1958000.0" ThrustCoEfficient="0.409"/><DataPoint WindSpeed="14.0" PowerOutput="1988000.0" ThrustCoEfficient="0.314"/><DataPoint WindSpeed="15.0" PowerOutput="1997000.0" ThrustCoEfficient="0.249"/><DataPoint WindSpeed="16.0" PowerOutput="1999000.0" ThrustCoEfficient="0.202"/><DataPoint WindSpeed="17.0" PowerOutput="2000000.0" ThrustCoEfficient="0.167"/><DataPoint WindSpeed="18.0" PowerOutput="2000000.0" ThrustCoEfficient="0.14"/><DataPoint WindSpeed="19.0" PowerOutput="2000000.0" ThrustCoEfficient="0.118"/><DataPoint WindSpeed="20.0" PowerOutput="2000000.0" ThrustCoEfficient="0.101"/><DataPoint WindSpeed="21.0" PowerOutput="2000000.0" ThrustCoEfficient="0.088"/><DataPoint WindSpeed="22.0" PowerOutput="2000000.0" ThrustCoEfficient="0.076"/><DataPoint WindSpeed="23.0" PowerOutput="2000000.0" ThrustCoEfficient="0.067"/><DataPoint WindSpeed="24.0" PowerOutput="2000000.0" ThrustCoEfficient="0.059"/><DataPoint WindSpeed="25.0" PowerOutput="2000000.0" ThrustCoEfficient="0.052"/></DataTable></PerformanceTable></WindTurbineGenerator>

py_wake/examples/data/__init__.py

+import os
+wtg_path = os.path.dirname(__file__) + "/"

py_wake/tests/test_windturbines.py

@@ -6,6 +6,27 @@ import numpy as np
 from py_wake.tests import npt
 
 
+def test_from_WAsP_wtg():
+    import os
+    from py_wake.examples.data import wtg_path
+    from py_wake.wind_turbines import WindTurbines
+    vestas_v80_wtg = os.path.join(wtg_path, 'Vestas-V80.wtg')
+    NEG_2750_wtg = os.path.join(wtg_path, 'NEG-Micon-2750.wtg')
+    wts_wtg = WindTurbines.from_WAsP_wtg([vestas_v80_wtg, NEG_2750_wtg])
+
+    assert(wts_wtg.name(types=0) == 'Vestas V80 (2MW, Offshore)')
+    assert(wts_wtg.diameter(types=0) == 80)
+    assert(wts_wtg.hub_height(types=0) == 67)
+    npt.assert_array_equal(wts_wtg.power(np.array([0, 3, 5, 9, 18, 26]), type_i=0), np.array([0, 0, 154000, 996000, 2000000, 0]))
+    npt.assert_array_equal(wts_wtg.ct(np.array([1, 4, 7, 9, 17, 27]), type_i=0), np.array([0, 0.818, 0.805, 0.807, 0.167, 0]))
+
+    assert(wts_wtg.name(types=1) == 'NEG-Micon 2750/92 (2750 kW)')
+    assert(wts_wtg.diameter(types=1) == 92)
+    assert(wts_wtg.hub_height(types=1) == 70)
+    npt.assert_array_equal(wts_wtg.power(np.array([0, 3, 5, 9, 18, 26]), type_i=1), np.array([0, 0, 185000, 1326000, 2748000, 0]))
+    npt.assert_array_equal(wts_wtg.ct(np.array([1, 4, 7, 9, 17, 27]), type_i=1), np.array([0, 0.871, 0.841, 0.797, 0.175, 0]))
+
+
 def test_twotype_windturbines():
     from py_wake.wind_turbines import WindTurbines
     v80 = V80()

py_wake/wind_turbines.py

 import numpy as np
+import xml.etree.ElementTree as ET
 
 
 class WindTurbines():
@@ -158,6 +159,70 @@ class WindTurbines():
         ax.legend(loc=1)
         ax.axis('equal')
 
+    @classmethod
+    def from_WAsP_wtg(cls, wtg_file, power_unit='W'):
+        """ Parse the one/multiple .wtg file(s) (xml) to initilize an
+        WindTurbines object.
+
+        Parameters
+        ----------
+        wtg_file : string or a list of string
+            A string denoting the .wtg file, which is exported from WAsP.
+
+        Returns
+        -------
+        an object of WindTurbines.
+
+        Note: it is assumed that the power_unit inside multiple .wtg files
+        is the same, i.e., power_unit.
+        """
+        if type(wtg_file) is not list:
+            wtg_file_list = [wtg_file]
+        else:
+            wtg_file_list = wtg_file
+
+        names = []
+        diameters = []
+        hub_heights = []
+        ct_funcs = []
+        power_funcs = []
+
+        for wtg_file in wtg_file_list:
+            tree = ET.parse(wtg_file)
+            root = tree.getroot()
+            # Reading data from wtg_file
+            name = root.attrib['Description']
+            diameter = np.float(root.attrib['RotorDiameter'])
+            hub_height = np.float(root.find('SuggestedHeights').find('Height').text)
+            ws_cutin = np.float(root.find('PerformanceTable').find('StartStopStrategy').attrib['LowSpeedCutIn'])
+            ws_cutout = np.float(root.find('PerformanceTable').find('StartStopStrategy').attrib['HighSpeedCutOut'])
+
+            i_point = 0
+            for DataPoint in root.iter('DataPoint'):
+                i_point = i_point + 1
+                ws = np.float(DataPoint.attrib['WindSpeed'])
+                Ct = np.float(DataPoint.attrib['ThrustCoEfficient'])
+                power = np.float(DataPoint.attrib['PowerOutput'])
+                if i_point == 1:
+                    dt = np.array([[ws, Ct, power]])
+                else:
+                    dt = np.append(dt, np.array([[ws, Ct, power]]), axis=0)
+
+            rated_power = np.max(dt[:, 2])
+            ws = dt[:, 0]
+            ct = dt[:, 1]
+            power = dt[:, 2]
+
+            names.append(name)
+            diameters.append(diameter)
+            hub_heights.append(hub_height)
+            ct_funcs.append(lambda u, ws=ws, ct=ct: np.interp(u, ws, ct, left=0, right=0))
+            power_funcs.append(lambda u, ws=ws, power=power: np.interp(u, ws, power, left=0, right=0))
+
+        return cls(names=names, diameters=diameters,
+                   hub_heights=hub_heights, ct_funcs=ct_funcs,
+                   power_funcs=power_funcs, power_unit=power_unit)
+
 
 class OneTypeWindTurbines(WindTurbines):
 
@@ -222,6 +287,10 @@ def dummy_thrust(ws_cut_in=3, ws_cut_out=25, ws_rated=12, ct_rated=8 / 9):
 
 def main():
     if __name__ == '__main__':
+        import os.path
+        import matplotlib.pyplot as plt
+        from py_wake.examples.data import wtg_path
+
         wts = WindTurbines(names=['tb1', 'tb2'],
                            diameters=[80, 120],
                            hub_heights=[70, 110],
@@ -232,7 +301,7 @@ def main():
                            power_unit='kW')
 
         ws = np.arange(25)
-        import matplotlib.pyplot as plt
+
         plt.plot(ws, wts.power(ws, 0), label=wts.name(0))
         plt.plot(ws, wts.power(ws, 1), label=wts.name(1))
         plt.legend()
@@ -247,5 +316,27 @@ def main():
         plt.ylim([-50, 150])
         plt.show()
 
+        # Exmaple using two wtg files to initialize a wind turbine
+#        vestas_v80_wtg = './examples/data/Vestas-V80.wtg'
+#        NEG_2750_wtg = './examples/data/NEG-Micon-2750.wtg'
+
+#        data_folder = Path('./examples/data/')
+#        vestas_v80_wtg = data_folder / 'Vestas-V80.wtg'
+#        NEG_2750_wtg = data_folder / 'NEG-Micon-2750.wtg'
+        vestas_v80_wtg = os.path.join(wtg_path, 'Vestas-V80.wtg')
+        NEG_2750_wtg = os.path.join(wtg_path, 'NEG-Micon-2750.wtg')
+        wts_wtg = WindTurbines.from_WAsP_wtg([vestas_v80_wtg, NEG_2750_wtg])
+
+        ws = np.arange(30)
+
+        plt.plot(ws, wts_wtg.power(ws, 0), label=wts_wtg.name(0))
+        plt.plot(ws, wts_wtg.power(ws, 1), label=wts_wtg.name(1))
+        plt.legend()
+        plt.show()
+        plt.plot(ws, wts_wtg.ct(ws, 0), label=wts_wtg.name(0))
+        plt.plot(ws, wts_wtg.ct(ws, 1), label=wts_wtg.name(1))
+        plt.legend()
+        plt.show()
+
 
 main()