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import numpy as np
from numpy import newaxis as na
from abc import abstractmethod, ABC
class Shear(ABC):
@abstractmethod
def __call__(self, WS_ilk, WD_ilk, h_i):
"""Get wind speed at height
Parameters
----------
WS_ilk : array_like
wind speed
WD_ilk : array_like
wind direction
h_i : array_like
height
Returns
-------
WS_ilk : array_like
Wind speed at height h_i
"""
class PowerShear():
def __init__(self, h_ref, alpha, interp_method='nearest'):
from py_wake.site._site import get_sector_xr
self.alpha = get_sector_xr(alpha, "Power shear coefficient")
self.interp_method = interp_method
def __call__(self, WS, WD, h):
alpha = self.alpha.interp_all(WD, method=self.interp_method)
if alpha.shape == ():
alpha = alpha.data
return (h / self.h_ref) ** alpha * WS
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# ======================================================================================================================
# Potentially the code below can be used to implement power/log shear interpolation between grid layers
# ======================================================================================================================
# class InterpolationShear(ABC):
# @abstractmethod
# def setup(self, ds):
# """"""
#
# @abstractmethod
# def __call__(self):
# """"""
#
#
# class LinearInterpolationShear():
# def setup(self, ds):
# pass
#
# def __call__(self, WS_ilk, WD_ilk, h_i):
# return WS_ilk
#
#
# class PowerInterpolationShear():
# """Apply wind shear coefficient based on speed-up factor at different
# # height and a reference far field wind shear coefficient (alpha_far)"""
#
# def __init__(self, alpha_far=.143):
# self.alpha_far = alpha_far
#
# def setup(self, ds):
# ds['wind_shear'] = copy.deepcopy(ds['spd'])
#
# heights = ds['wind_shear'].coords['z'].data
#
# # if there is only one layer, assign default value
# if len(heights) == 1:
#
# ds['wind_shear'].data = (np.zeros_like(ds['wind_shear'].data) + self.alpha_far)
#
# print('Note there is only one layer of wind resource data, ' +
# 'wind shear are assumed as uniform, i.e., {0}'.format(self.alpha_far))
# else:
# ds['wind_shear'].data[:, :, 0, :] = (self.alpha_far +
# np.log(ds['spd'].data[:, :, 0, :] / ds['spd'].data[:, :, 1, :]) /
# np.log(heights[0] / heights[1]))
#
# for h in range(1, len(heights)):
# ds['wind_shear'].data[:, :, h, :] = (
# self.alpha_far +
# np.log(ds['spd'].data[:, :, h, :] / ds['spd'].data[:, :, h - 1, :]) /
# np.log(heights[h] / heights[h - 1]))
#
# def __call__(self, WS_ilk, WD_ilk, h_i):
# ????? WS_ilk = (WS_ilk * (H_hub / self.height_ref) ** wind_shear_il[i_wt, l_wd])