def test_PVSystem_get_irradiance():
system = pvsystem.PVSystem(surface_tilt=32, surface_azimuth=135)
times = pd.DatetimeIndex(start='20160101 1200-0700',
end='20160101 1800-0700', freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({'dni':[900,0], 'ghi':[600,0], 'dhi':[100,0]},
index=times)
irradiance = system.get_irradiance(solar_position['apparent_zenith'],
solar_position['azimuth'],
irrads['dni'],
irrads['ghi'],
irrads['dhi'])
expected = pd.DataFrame(data=np.array(
[[ 883.65494055, 745.86141676, 137.79352379, 126.397131 ,
11.39639279],
[ 0. , -0. , 0. , 0. , 0. ]]),
columns=['poa_global', 'poa_direct',
'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=times)
assert_frame_equal(irradiance, expected, check_less_precise=2)
def test_get_irradiance():
system = tracking.SingleAxisTracker(max_angle=90, axis_tilt=30,
axis_azimuth=180, gcr=2.0/7.0,
backtrack=True)
times = pd.DatetimeIndex(start='20160101 1200-0700',
end='20160101 1800-0700', freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({'dni':[900,0], 'ghi':[600,0], 'dhi':[100,0]},
index=times)
solar_zenith = solar_position['apparent_zenith']
solar_azimuth = solar_position['azimuth']
tracker_data = system.singleaxis(solar_zenith, solar_azimuth)
irradiance = system.get_irradiance(irrads['dni'],
irrads['ghi'],
irrads['dhi'],
solar_zenith=solar_zenith,
solar_azimuth=solar_azimuth,
surface_tilt=tracker_data['surface_tilt'],
surface_azimuth=tracker_data['surface_azimuth'])
expected = pd.DataFrame(data=np.array(
[[ 961.80070, 815.94490, 145.85580, 135.32820,
10.52757492],
[ nan, nan, nan, nan,
nan]]),
columns=['poa_global', 'poa_direct',
'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=times)
assert_frame_equal(irradiance, expected, check_less_precise=2)
def test_PVSystem_get_irradiance():
system = pvsystem.PVSystem(surface_tilt=32, surface_azimuth=135)
times = pd.DatetimeIndex(start='20160101 1200-0700',
end='20160101 1800-0700', freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({'dni':[900,0], 'ghi':[600,0], 'dhi':[100,0]},
index=times)
irradiance = system.get_irradiance(solar_position['apparent_zenith'],
solar_position['azimuth'],
irrads['dni'],
irrads['ghi'],
irrads['dhi'])
expected = pd.DataFrame(data=np.array(
[[ 883.65494055, 745.86141676, 137.79352379, 126.397131 ,
11.39639279],
[ 0. , -0. , 0. , 0. , 0. ]]),
columns=['poa_global', 'poa_direct',
'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=times)
irradiance = np.round(irradiance, 4)
expected = np.round(expected, 4)
assert_frame_equal(irradiance, expected)
def get_DNI(self):
"""
Extract DNI from METPV-11 data. Daily METPV-11 data records.
The raw data in METPV-11 is the incidence on the horizontal plane, that is, DNI*cos(d).
d is the incidence anlge.
:return: a dataframe that contains the DNI
"""
ngo = Location(latitude=self.latitude,
longitude=self.longitude,
altitude=0,
tz='Japan')
solar_pos = ngo.get_solarposition(
pd.DatetimeIndex(self.hour_df['avg_time']))
cosd = aoi_projection(surface_tilt=0,
surface_azimuth=0,
solar_zenith=solar_pos['apparent_zenith'],
solar_azimuth=solar_pos['azimuth'])
dni_arr = self.hour_df['DHI'] / cosd
dni_arr = np.maximum(dni_arr, 0)
return dni_arr
def test_get_irradiance():
system = tracking.SingleAxisTracker(max_angle=90, axis_tilt=30,
axis_azimuth=180, gcr=2.0/7.0,
backtrack=True)
times = pd.DatetimeIndex(start='20160101 1200-0700',
end='20160101 1800-0700', freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({'dni':[900,0], 'ghi':[600,0], 'dhi':[100,0]},
index=times)
solar_zenith = solar_position['apparent_zenith']
solar_azimuth = solar_position['azimuth']
tracker_data = system.singleaxis(solar_zenith, solar_azimuth)
irradiance = system.get_irradiance(tracker_data['surface_tilt'],
tracker_data['surface_azimuth'],
solar_zenith,
solar_azimuth,
irrads['dni'],
irrads['ghi'],
irrads['dhi'])
expected = pd.DataFrame(data=np.array(
[[961.80070, 815.94490, 145.85580, 135.32820, 10.52757492],
[nan, nan, nan, nan, nan]]),
columns=['poa_global', 'poa_direct',
'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=times)
assert_frame_equal(irradiance, expected, check_less_precise=2)
def compute_irradiance(latitude: float, longitude: float, dt: datetime,
cloud_coverage: float) -> float:
"""Compute the irradiance received on a location at a specific time.
This uses pvlib to
1) compute clear-sky irradiance as Global Horizontal Irradiance (GHI),
which includes both Direct Normal Irradiance (DNI)
and Diffuse Horizontal Irradiance (DHI).
2) adjust the GHI for cloud coverage
"""
site = Location(latitude, longitude, tz=dt.tzinfo)
solpos = site.get_solarposition(pd.DatetimeIndex([dt]))
ghi_clear = site.get_clearsky(pd.DatetimeIndex([dt]),
solar_position=solpos).loc[dt]["ghi"]
return ghi_clear_to_ghi(ghi_clear, cloud_coverage)
def tilt_irr(self,
surface_tilt=None,
surface_azimuth=180,
include_solar_pos=False) -> pd.DataFrame:
"""
Calculate the irradiances(DNI) and angle of incidence (aoi) on a tilted surface
:param surface_tilt: The surface tilt angle (in degree).
:param surface_azimuth: The azimuth angle of the surface. Default is 180 degrees.
:param include_solar_pos: whether to include solar position in the output dataframe.
:return: a dataframe with calculated solar incidence.
"""
if surface_tilt is None:
surface_tilt = self.latitude
ngo = Location(latitude=self.latitude,
longitude=self.longitude,
altitude=0,
tz='Japan')
solar_pos = ngo.get_solarposition(
pd.DatetimeIndex(self.hour_df['avg_time']))
dni_arr = self.get_DNI()
irrad_df = total_irrad(surface_tilt=surface_tilt,
surface_azimuth=surface_azimuth,
apparent_zenith=solar_pos['apparent_zenith'],
azimuth=solar_pos['azimuth'],
dni=dni_arr,
ghi=self.hour_df['GHI'],
dhi=self.hour_df['dHI'])
irrad_df['aoi'] = aoi(surface_tilt, surface_azimuth,
solar_pos['zenith'], solar_pos['azimuth'])
irrad_df['DNI'] = dni_arr
n_df = pd.concat([self.hour_df, irrad_df], axis=1)
if include_solar_pos:
n_df = pd.concat([n_df, solar_pos], axis=1)
return n_df
def single_axis_irr(self, include_track_angles=False):
"""
Calculate the irradiances incident on a surface that mounted on an ideal single-axis tracker
:param include_track_angles: whether to include the tracker angles into the returned dataframe.
:return: a dataframe of sun irradiances on the single-axis tracked surface.
"""
tracker = SingleAxisTracker(axis_tilt=0,
axis_azimuth=0,
max_angle=180,
backtrack=False)
ngo = Location(latitude=self.latitude,
longitude=self.longitude,
altitude=0,
tz='Japan')
solar_pos = ngo.get_solarposition(
pd.DatetimeIndex(self.hour_df['avg_time']))
tracker_angle = tracker.singleaxis(
apparent_azimuth=solar_pos['azimuth'],
apparent_zenith=solar_pos['apparent_zenith'])
dni_arr = self.get_DNI()
irr = tracker.get_irradiance(
dni=dni_arr,
ghi=self.hour_df['GHI'],
dhi=self.hour_df['dHI'],
solar_zenith=solar_pos['apparent_zenith'],
solar_azimuth=solar_pos['azimuth'],
surface_tilt=tracker_angle['surface_tilt'],
surface_azimuth=tracker_angle['surface_azimuth'])
irr['DNI'] = dni_arr
n_df = pd.concat([self.hour_df, irr], axis=1)
if include_track_angles == True:
n_df = pd.concat([n_df, tracker_angle], axis=1)
return n_df
def test_get_irradiance():
system = tracking.SingleAxisTracker(max_angle=90,
axis_tilt=30,
axis_azimuth=180,
gcr=2.0 / 7.0,
backtrack=True)
times = pd.date_range(start='20160101 1200-0700',
end='20160101 1800-0700',
freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({
'dni': [900, 0],
'ghi': [600, 0],
'dhi': [100, 0]
},
index=times)
solar_zenith = solar_position['apparent_zenith']
solar_azimuth = solar_position['azimuth']
# invalid warnings already generated in horizon test above,
# no need to clutter test output here
with np.errstate(invalid='ignore'):
tracker_data = system.singleaxis(solar_zenith, solar_azimuth)
# some invalid values in irradiance.py. not our problem here
with np.errstate(invalid='ignore'):
irradiance = system.get_irradiance(tracker_data['surface_tilt'],
tracker_data['surface_azimuth'],
solar_zenith, solar_azimuth,
irrads['dni'], irrads['ghi'],
irrads['dhi'])
expected = pd.DataFrame(data=np.array(
[[961.80070, 815.94490, 145.85580, 135.32820, 10.52757492],
[nan, nan, nan, nan, nan]]),
columns=[
'poa_global', 'poa_direct', 'poa_diffuse',
'poa_sky_diffuse', 'poa_ground_diffuse'
],
index=times)
assert_frame_equal(irradiance, expected, check_less_precise=2)
def test_get_irradiance():
system = tracking.SingleAxisTracker(max_angle=90,
axis_tilt=30,
axis_azimuth=180,
gcr=2.0 / 7.0,
backtrack=True)
times = pd.DatetimeIndex(start='20160101 1200-0700',
end='20160101 1800-0700',
freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({
'dni': [900, 0],
'ghi': [600, 0],
'dhi': [100, 0]
},
index=times)
solar_zenith = solar_position['apparent_zenith']
solar_azimuth = solar_position['azimuth']
tracker_data = system.singleaxis(solar_zenith, solar_azimuth)
irradiance = system.get_irradiance(
irrads['dni'],
irrads['ghi'],
irrads['dhi'],
solar_zenith=solar_zenith,
solar_azimuth=solar_azimuth,
surface_tilt=tracker_data['surface_tilt'],
surface_azimuth=tracker_data['surface_azimuth'])
expected = pd.DataFrame(data=np.array(
[[142.71652464, 87.50125991, 55.21526473, 44.68768982, 10.52757492],
[nan, nan, nan, nan, nan]]),
columns=[
'poa_global', 'poa_direct', 'poa_diffuse',
'poa_sky_diffuse', 'poa_ground_diffuse'
],
index=times)
irradiance = np.round(irradiance, 4)
expected = np.round(expected, 4)
assert_frame_equal(irradiance, expected)
def test_get_irradiance():
system = tracking.SingleAxisTracker(max_angle=90, axis_tilt=30,
axis_azimuth=180, gcr=2.0/7.0,
backtrack=True)
times = pd.date_range(start='20160101 1200-0700',
end='20160101 1800-0700', freq='6H')
location = Location(latitude=32, longitude=-111)
solar_position = location.get_solarposition(times)
irrads = pd.DataFrame({'dni': [900, 0], 'ghi': [600, 0], 'dhi': [100, 0]},
index=times)
solar_zenith = solar_position['apparent_zenith']
solar_azimuth = solar_position['azimuth']
# invalid warnings already generated in horizon test above,
# no need to clutter test output here
with np.errstate(invalid='ignore'):
tracker_data = system.singleaxis(solar_zenith, solar_azimuth)
# some invalid values in irradiance.py. not our problem here
with np.errstate(invalid='ignore'):
irradiance = system.get_irradiance(tracker_data['surface_tilt'],
tracker_data['surface_azimuth'],
solar_zenith,
solar_azimuth,
irrads['dni'],
irrads['ghi'],
irrads['dhi'])
expected = pd.DataFrame(data=np.array(
[[961.80070, 815.94490, 145.85580, 135.32820, 10.52757492],
[nan, nan, nan, nan, nan]]),
columns=['poa_global', 'poa_direct',
'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=times)
assert_frame_equal(irradiance, expected, check_less_precise=2)
def matlab2datetime(matlab_datenum):
day = dt.datetime.fromordinal(int(matlab_datenum))
dayfrac = dt.timedelta(days=matlab_datenum%1) - dt.timedelta(days = 366)
return day + dayfrac + dt.timedelta(hours=8)
time = [matlab2datetime(tval) for tval in mat['time_day']]
# plot ghi to check
ghi=pd.DataFrame(GHI,time,columns=['ghi'])
ax=ghi.plot()
ax.set_xlabel('Time [UTC]]')
ax.set_ylabel('GHI [W/m²]')
'''separate dhi and dni from ghi'''
sd = Location(32.883729,-117.239341)
sza=sd.get_solarposition(time).zenith # zenith angle
out=pvlib.irradiance.erbs(GHI,sza,pd.DatetimeIndex(time)) #using erbs method
# plot ghi dni dhi
irr=pd.concat([ghi,out['dni'],out['dhi']],axis=1) #concatenate irradiances
ax3=irr.plot(title='Erbs method')
ax3.set_xlabel('Time [UTC]')
ax3.set_ylabel('Irradiance [W/m²]')
'''convert irradiance to power'''
#load modules and inverters
sandia_modules = pvlib.pvsystem.retrieve_sam('SandiaMod')
cec_inverters = pvlib.pvsystem.retrieve_sam('cecinverter')
# sma_cols = [col for col in cec_inverters.columns if 'SMA' in col] # use to look for strings
# Equipment at EBU2:
class ForecastModel(object):
"""
An object for querying and holding forecast model information for
use within the pvlib library.
Simplifies use of siphon library on a THREDDS server.
Parameters
----------
model_type: string
UNIDATA category in which the model is located.
model_name: string
Name of the UNIDATA forecast model.
set_type: string
Model dataset type.
Attributes
----------
access_url: string
URL specifying the dataset from data will be retrieved.
base_tds_url : string
The top level server address
catalog_url : string
The url path of the catalog to parse.
data: pd.DataFrame
Data returned from the query.
data_format: string
Format of the forecast data being requested from UNIDATA.
dataset: Dataset
Object containing information used to access forecast data.
dataframe_variables: list
Model variables that are present in the data.
datasets_list: list
List of all available datasets.
fm_models: Dataset
TDSCatalog object containing all available
forecast models from UNIDATA.
fm_models_list: list
List of all available forecast models from UNIDATA.
latitude: list
A list of floats containing latitude values.
location: Location
A pvlib Location object containing geographic quantities.
longitude: list
A list of floats containing longitude values.
lbox: boolean
Indicates the use of a location bounding box.
ncss: NCSS object
NCSS
model_name: string
Name of the UNIDATA forecast model.
model: Dataset
A dictionary of Dataset object, whose keys are the name of the
dataset's name.
model_url: string
The url path of the dataset to parse.
modelvariables: list
Common variable names that correspond to queryvariables.
query: NCSS query object
NCSS object used to complete the forecast data retrival.
queryvariables: list
Variables that are used to query the THREDDS Data Server.
time: DatetimeIndex
Time range.
variables: dict
Defines the variables to obtain from the weather
model and how they should be renamed to common variable names.
units: dict
Dictionary containing the units of the standard variables
and the model specific variables.
vert_level: float or integer
Vertical altitude for query data.
"""
access_url_key = 'NetcdfSubset'
catalog_url = 'https://thredds.ucar.edu/thredds/catalog.xml'
base_tds_url = catalog_url.split('/thredds/')[0]
data_format = 'netcdf'
units = {
'temp_air': 'C',
'wind_speed': 'm/s',
'ghi': 'W/m^2',
'ghi_raw': 'W/m^2',
'dni': 'W/m^2',
'dhi': 'W/m^2',
'total_clouds': '%',
'low_clouds': '%',
'mid_clouds': '%',
'high_clouds': '%'
}
def __init__(self, model_type, model_name, set_type, vert_level=None):
self.model_type = model_type
self.model_name = model_name
self.set_type = set_type
self.connected = False
self.vert_level = vert_level
def connect_to_catalog(self):
self.catalog = TDSCatalog(self.catalog_url)
self.fm_models = TDSCatalog(
self.catalog.catalog_refs[self.model_type].href)
self.fm_models_list = sorted(list(self.fm_models.catalog_refs.keys()))
try:
model_url = self.fm_models.catalog_refs[self.model_name].href
except ParseError:
raise ParseError(self.model_name + ' model may be unavailable.')
try:
self.model = TDSCatalog(model_url)
except HTTPError:
try:
self.model = TDSCatalog(model_url)
except HTTPError:
raise HTTPError(self.model_name + ' model may be unavailable.')
self.datasets_list = list(self.model.datasets.keys())
self.set_dataset()
self.connected = True
def __repr__(self):
return '{}, {}'.format(self.model_name, self.set_type)
def set_dataset(self):
'''
Retrieves the designated dataset, creates NCSS object, and
creates a NCSS query object.
'''
keys = list(self.model.datasets.keys())
labels = [item.split()[0].lower() for item in keys]
if self.set_type == 'best':
self.dataset = self.model.datasets[keys[labels.index('best')]]
elif self.set_type == 'latest':
self.dataset = self.model.datasets[keys[labels.index('latest')]]
elif self.set_type == 'full':
self.dataset = self.model.datasets[keys[labels.index('full')]]
self.access_url = self.dataset.access_urls[self.access_url_key]
self.ncss = NCSS(self.access_url)
self.query = self.ncss.query()
def set_query_time_range(self, start, end):
"""
Parameters
----------
start : datetime.datetime, pandas.Timestamp
Must be tz-localized.
end : datetime.datetime, pandas.Timestamp
Must be tz-localized.
Notes
-----
Assigns ``self.start``, ``self.end``. Modifies ``self.query``
"""
self.start = pd.Timestamp(start)
self.end = pd.Timestamp(end)
if self.start.tz is None or self.end.tz is None:
raise TypeError('start and end must be tz-localized')
self.query.time_range(self.start, self.end)
def set_query_latlon(self):
'''
Sets the NCSS query location latitude and longitude.
'''
if (isinstance(self.longitude, list)
and isinstance(self.latitude, list)):
self.lbox = True
# west, east, south, north
self.query.lonlat_box(self.longitude[0], self.longitude[1],
self.latitude[0], self.latitude[1])
else:
self.lbox = False
self.query.lonlat_point(self.longitude, self.latitude)
def set_location(self, tz, latitude, longitude):
'''
Sets the location for the query.
Parameters
----------
tz: tzinfo
Timezone of the query
latitude: float
Latitude of the query
longitude: float
Longitude of the query
Notes
-----
Assigns ``self.location``.
'''
self.location = Location(latitude, longitude, tz=tz)
def get_data(self,
latitude,
longitude,
start,
end,
vert_level=None,
query_variables=None,
close_netcdf_data=True,
**kwargs):
"""
Submits a query to the UNIDATA servers using Siphon NCSS and
converts the netcdf data to a pandas DataFrame.
Parameters
----------
latitude: float
The latitude value.
longitude: float
The longitude value.
start: datetime or timestamp
The start time.
end: datetime or timestamp
The end time.
vert_level: None, float or integer, default None
Vertical altitude of interest.
query_variables: None or list, default None
If None, uses self.variables.
close_netcdf_data: bool, default True
Controls if the temporary netcdf data file should be closed.
Set to False to access the raw data.
**kwargs:
Additional keyword arguments are silently ignored.
Returns
-------
forecast_data : DataFrame
column names are the weather model's variable names.
"""
if not self.connected:
self.connect_to_catalog()
if vert_level is not None:
self.vert_level = vert_level
if query_variables is None:
self.query_variables = list(self.variables.values())
else:
self.query_variables = query_variables
self.set_query_time_range(start, end)
self.latitude = latitude
self.longitude = longitude
self.set_query_latlon() # modifies self.query
self.set_location(self.start.tz, latitude, longitude)
if self.vert_level is not None:
self.query.vertical_level(self.vert_level)
self.query.variables(*self.query_variables)
self.query.accept(self.data_format)
self.netcdf_data = self.ncss.get_data(self.query)
# might be better to go to xarray here so that we can handle
# higher dimensional data for more advanced applications
self.data = self._netcdf2pandas(self.netcdf_data, self.query_variables,
self.start, self.end)
if close_netcdf_data:
self.netcdf_data.close()
return self.data
def process_data(self, data, **kwargs):
"""
Defines the steps needed to convert raw forecast data
into processed forecast data. Most forecast models implement
their own version of this method which also call this one.
Parameters
----------
data: DataFrame
Raw forecast data
Returns
-------
data: DataFrame
Processed forecast data.
"""
data = self.rename(data)
return data
def get_processed_data(self, *args, **kwargs):
"""
Get and process forecast data.
Parameters
----------
*args: positional arguments
Passed to get_data
**kwargs: keyword arguments
Passed to get_data and process_data
Returns
-------
data: DataFrame
Processed forecast data
"""
return self.process_data(self.get_data(*args, **kwargs), **kwargs)
def rename(self, data, variables=None):
"""
Renames the columns according the variable mapping.
Parameters
----------
data: DataFrame
variables: None or dict, default None
If None, uses self.variables
Returns
-------
data: DataFrame
Renamed data.
"""
if variables is None:
variables = self.variables
return data.rename(columns={y: x for x, y in variables.items()})
def _netcdf2pandas(self, netcdf_data, query_variables, start, end):
"""
Transforms data from netcdf to pandas DataFrame.
Parameters
----------
data: netcdf
Data returned from UNIDATA NCSS query.
query_variables: list
The variables requested.
start: Timestamp
The start time
end: Timestamp
The end time
Returns
-------
pd.DataFrame
"""
# set self.time
try:
time_var = 'time'
self.set_time(netcdf_data.variables[time_var])
except KeyError:
# which model does this dumb thing?
time_var = 'time1'
self.set_time(netcdf_data.variables[time_var])
data_dict = {}
for key, data in netcdf_data.variables.items():
# if accounts for possibility of extra variable returned
if key not in query_variables:
continue
squeezed = data[:].squeeze()
if squeezed.ndim == 1:
data_dict[key] = squeezed
elif squeezed.ndim == 2:
for num, data_level in enumerate(squeezed.T):
data_dict[key + '_' + str(num)] = data_level
else:
raise ValueError('cannot parse ndim > 2')
data = pd.DataFrame(data_dict, index=self.time)
# sometimes data is returned as hours since T0
# where T0 is before start. Then the hours between
# T0 and start are added *after* end. So sort and slice
# to remove the garbage
data = data.sort_index().loc[start:end]
return data
def set_time(self, time):
'''
Converts time data into a pandas date object.
Parameters
----------
time: netcdf
Contains time information.
Returns
-------
pandas.DatetimeIndex
'''
times = num2date(time[:].squeeze(),
time.units,
only_use_cftime_datetimes=False,
only_use_python_datetimes=True)
self.time = pd.DatetimeIndex(pd.Series(times), tz=self.location.tz)
def cloud_cover_to_ghi_linear(self,
cloud_cover,
ghi_clear,
offset=35,
**kwargs):
"""
Convert cloud cover to GHI using a linear relationship.
0% cloud cover returns ghi_clear.
100% cloud cover returns offset*ghi_clear.
Parameters
----------
cloud_cover: numeric
Cloud cover in %.
ghi_clear: numeric
GHI under clear sky conditions.
offset: numeric, default 35
Determines the minimum GHI.
kwargs
Not used.
Returns
-------
ghi: numeric
Estimated GHI.
References
----------
Larson et. al. "Day-ahead forecasting of solar power output from
photovoltaic plants in the American Southwest" Renewable Energy
91, 11-20 (2016).
"""
offset = offset / 100.
cloud_cover = cloud_cover / 100.
ghi = (offset + (1 - offset) * (1 - cloud_cover)) * ghi_clear
return ghi
def cloud_cover_to_irradiance_clearsky_scaling(self,
cloud_cover,
method='linear',
**kwargs):
"""
Estimates irradiance from cloud cover in the following steps:
1. Determine clear sky GHI using Ineichen model and
climatological turbidity.
2. Estimate cloudy sky GHI using a function of
cloud_cover e.g.
:py:meth:`~ForecastModel.cloud_cover_to_ghi_linear`
3. Estimate cloudy sky DNI using the DISC model.
4. Calculate DHI from DNI and GHI.
Parameters
----------
cloud_cover : Series
Cloud cover in %.
method : str, default 'linear'
Method for converting cloud cover to GHI.
'linear' is currently the only option.
**kwargs
Passed to the method that does the conversion
Returns
-------
irrads : DataFrame
Estimated GHI, DNI, and DHI.
"""
solpos = self.location.get_solarposition(cloud_cover.index)
cs = self.location.get_clearsky(cloud_cover.index,
model='ineichen',
solar_position=solpos)
method = method.lower()
if method == 'linear':
ghi = self.cloud_cover_to_ghi_linear(cloud_cover, cs['ghi'],
**kwargs)
else:
raise ValueError('invalid method argument')
dni = disc(ghi, solpos['zenith'], cloud_cover.index)['dni']
dhi = ghi - dni * np.cos(np.radians(solpos['zenith']))
irrads = pd.DataFrame({'ghi': ghi, 'dni': dni, 'dhi': dhi}).fillna(0)
return irrads
def cloud_cover_to_transmittance_linear(self,
cloud_cover,
offset=0.75,
**kwargs):
"""
Convert cloud cover to atmospheric transmittance using a linear
model.
0% cloud cover returns offset.
100% cloud cover returns 0.
Parameters
----------
cloud_cover : numeric
Cloud cover in %.
offset : numeric, default 0.75
Determines the maximum transmittance.
kwargs
Not used.
Returns
-------
ghi : numeric
Estimated GHI.
"""
transmittance = ((100.0 - cloud_cover) / 100.0) * offset
return transmittance
def cloud_cover_to_irradiance_liujordan(self, cloud_cover, **kwargs):
"""
Estimates irradiance from cloud cover in the following steps:
1. Determine transmittance using a function of cloud cover e.g.
:py:meth:`~ForecastModel.cloud_cover_to_transmittance_linear`
2. Calculate GHI, DNI, DHI using the
:py:func:`pvlib.irradiance.liujordan` model
Parameters
----------
cloud_cover : Series
Returns
-------
irradiance : DataFrame
Columns include ghi, dni, dhi
"""
# in principle, get_solarposition could use the forecast
# pressure, temp, etc., but the cloud cover forecast is not
# accurate enough to justify using these minor corrections
solar_position = self.location.get_solarposition(cloud_cover.index)
dni_extra = get_extra_radiation(cloud_cover.index)
airmass = self.location.get_airmass(cloud_cover.index)
transmittance = self.cloud_cover_to_transmittance_linear(
cloud_cover, **kwargs)
irrads = liujordan(solar_position['apparent_zenith'],
transmittance,
airmass['airmass_absolute'],
dni_extra=dni_extra)
irrads = irrads.fillna(0)
return irrads
def cloud_cover_to_irradiance(self,
cloud_cover,
how='clearsky_scaling',
**kwargs):
"""
Convert cloud cover to irradiance. A wrapper method.
Parameters
----------
cloud_cover : Series
how : str, default 'clearsky_scaling'
Selects the method for conversion. Can be one of
clearsky_scaling or liujordan.
**kwargs
Passed to the selected method.
Returns
-------
irradiance : DataFrame
Columns include ghi, dni, dhi
"""
how = how.lower()
if how == 'clearsky_scaling':
irrads = self.cloud_cover_to_irradiance_clearsky_scaling(
cloud_cover, **kwargs)
elif how == 'liujordan':
irrads = self.cloud_cover_to_irradiance_liujordan(
cloud_cover, **kwargs)
else:
raise ValueError('invalid how argument')
return irrads
def kelvin_to_celsius(self, temperature):
"""
Converts Kelvin to celsius.
Parameters
----------
temperature: numeric
Returns
-------
temperature: numeric
"""
return temperature - 273.15
def isobaric_to_ambient_temperature(self, data):
"""
Calculates temperature from isobaric temperature.
Parameters
----------
data: DataFrame
Must contain columns pressure, temperature_iso,
temperature_dew_iso. Input temperature in K.
Returns
-------
temperature : Series
Temperature in K
"""
P = data['pressure'] / 100.0 # noqa: N806
Tiso = data['temperature_iso'] # noqa: N806
Td = data['temperature_dew_iso'] - 273.15 # noqa: N806
# saturation water vapor pressure
e = 6.11 * 10**((7.5 * Td) / (Td + 273.3))
# saturation water vapor mixing ratio
w = 0.622 * (e / (P - e))
temperature = Tiso - ((2.501 * 10.**6) / 1005.7) * w
return temperature
def uv_to_speed(self, data):
"""
Computes wind speed from wind components.
Parameters
----------
data : DataFrame
Must contain the columns 'wind_speed_u' and 'wind_speed_v'.
Returns
-------
wind_speed : Series
"""
wind_speed = np.sqrt(data['wind_speed_u']**2 + data['wind_speed_v']**2)
return wind_speed
def gust_to_speed(self, data, scaling=1 / 1.4):
"""
Computes standard wind speed from gust.
Very approximate and location dependent.
Parameters
----------
data : DataFrame
Must contain the column 'wind_speed_gust'.
Returns
-------
wind_speed : Series
"""
wind_speed = data['wind_speed_gust'] * scaling
return wind_speed
class PVModel(Forecast):
"""Model PV output based on irradiance or cloud coverage data"""
def __init__(self, config, section='PVSystem'):
"""Initialize PVModel
config configparser object with section [<section>]
<section> defaults to 'PVSystem'"""
try:
self._pvversion = pvlib.__version__
if self._pvversion > '0.8.1':
print("Warning --- pvmodel not tested with pvlib > 0.8.1")
elif self._pvversion < '0.8.0':
raise Exception("ERROR --- require pvlib >= 0.8.1")
super().__init__()
self.config = config
self._cfg = section
self.config['DEFAULT'][
'NominalEfficiency'] = '0.96' # nominal inverter efficiency, default of pvwatts model
self.config['DEFAULT'][
'TemperatureCoeff'] = '-0.005' # temperature coefficient of module, default of pvwatts model
self.config['DEFAULT'][
'TemperatureModel'] = 'open_rack_glass_glass' # https://pvlib-python.readthedocs.io/en/stable/generated/pvlib.temperature.sapm_cell.html
self.config['DEFAULT'][
'Altitude'] = '0' # default altitude sea level
self.config['DEFAULT'][
'Model'] = 'CEC' # default PV modeling stratey
self._weatherFields = {
'dwd': {
'temp_air':
'TTT', # translation: DWD parameter names --> pvlib parameter names
'wind_speed':
'FF', # Note that temp_air and temp_dew are in Celsius, TTT in Kelvin
'pressure': 'PPPP',
'temp_dew': 'Td',
'clouds': 'N'
},
'owm': {
'temp_air':
'temp', # translation: OWM parameter names --> pvlib parameter names
'wind_speed':
'wind_speed', # Note that temp_air and temp_dew are in Celsius, TTT in Kelvin
'pressure': 'pressure',
'temp_dew': 'dew_point',
'clouds': 'clouds'
}
}
self._weatherFields['dwd_s'] = self._weatherFields['dwd']
self._allow_experimental = self.config[self._cfg].getboolean(
'experimental',
False) # needs modification of pvlib.irradiance.erbs()
self._location = Location(
latitude=self.config[self._cfg].getfloat('Latitude'),
longitude=self.config[self._cfg].getfloat('Longitude'),
altitude=self.config[self._cfg].getfloat('Altitude'),
tz='UTC') # let's stay in UTC for the entire time ...
self._pvsystem = None # PV system, once defined with init_CEC() or init_PVWatts()
self._mc = None # Model chain, once defined in init_CEC() or init_PVWatts()
self._weather = None # weather data used for getIrradiance() and runModel()
self._cloud_cover_param = None # weather data parameter used for cloud coverage (see _weatherFields)
self.irradiance_model = None # model name if irradiance data calculated in getIrradiance()
self.irradiance = None # calculated irradiance data
self.pv_model = None # CEC or PVWatts once solar system is defined
self.SQLTable = self._cfg.lower(
) # which SQL table name is this data stored to (see DBRepository.loadData())
if (self.config[self._cfg].get('Model') == 'CEC'):
self._init_CEC()
else:
self._init_PVWatts()
except Exception as e:
print("pvmodel __init__: " + str(e))
sys.exit(1)
def _init_CEC(self):
"""Configure PV system based on actual components available in pvlib CEC database"""
try:
moduleName = self.config[self._cfg].get('ModuleName')
inverterName = self.config[self._cfg].get('InverterName')
tempModel = self.config[self._cfg].get('TemperatureModel')
self._pvsystem = PVSystem(
surface_tilt=self.config[self._cfg].getfloat('Tilt'),
surface_azimuth=self.config[self._cfg].getfloat('Azimuth'),
module_parameters=pvlib.pvsystem.retrieve_sam(
'cecmod')[moduleName],
inverter_parameters=pvlib.pvsystem.retrieve_sam(
'cecinverter')[inverterName],
strings_per_inverter=self.config[self._cfg].getint(
'NumStrings'),
modules_per_string=self.config[self._cfg].getint('NumPanels'),
temperature_model_parameters=TEMPERATURE_MODEL_PARAMETERS[
'sapm'][tempModel])
self._mc = ModelChain(self._pvsystem,
self._location,
aoi_model='physical',
spectral_model='no_loss')
self.pv_model = 'CEC'
except Exception as e:
print("init_CEC: " + str(e))
sys.exit(1)
def _init_PVWatts(self):
"""Configure PV system using simplified PVWatts model"""
try:
pvwatts_module = {
'pdc0': self.config[self._cfg].getfloat('SystemPower'),
'gamma_pdc':
self.config[self._cfg].getfloat('TemperatureCoeff')
}
pvwatts_inverter = {
'pdc0': self.config[self._cfg].getfloat('InverterPower'),
'eta_inv_nom':
self.config[self._cfg].getfloat('NominalEfficiency')
}
pvwatts_losses = {
'soiling': 0,
'shading': 0,
'snow': 0,
'mismatch': 0,
'wiring': 2,
'connections': 0.5,
'lid': 0,
'nameplate_rating': 0,
'age': 0,
'availability': 0
}
tempModel = self.config.get(self._cfg, 'TemperatureModel')
self._pvsystem = PVSystem(
surface_tilt=self.config[self._cfg].getfloat('Tilt'),
surface_azimuth=self.config[self._cfg].getfloat('Azimuth'),
module_parameters=pvwatts_module,
inverter_parameters=pvwatts_inverter,
losses_parameters=pvwatts_losses,
temperature_model_parameters=TEMPERATURE_MODEL_PARAMETERS[
'sapm'][tempModel])
self._mc = ModelChain.with_pvwatts(self._pvsystem,
self._location,
dc_model='pvwatts',
ac_model='pvwatts',
aoi_model='physical',
spectral_model='no_loss')
self.pv_model = 'PVWatts'
except Exception as e:
print("init_PVWatts: " + str(e))
sys.exit(1)
def getIrradiance(self, weather: Forecast, model='disc'):
"""Get irradiance data from weather files (see DWDForecast()) using various models
weather object eg. created by DWDForecast.weatherData
must contain: weatherData.DataTable, weatherData.IssueTime
model one of: 'disc', 'dirint', 'dirindex', 'erbs' (GHI decomposition models)
'erbs_kt' (as 'erbs', but with kt as input parameter; this needs a minor
modification to pvlib.irradiance.erbs)
'campbell_norman', 'clearsky_scaling' (cloud coverage to irradiance)
'clearsky' (clear sky model)
cloud_cover_param name of cloud cover parameter in weather"""
try:
try: # if weather is a Forecast object, this will work
weatherData = weather.DataTable # extract weather data table from weather
self.IssueTime = weather.IssueTime
f = self._weatherFields[
weather.
SQLTable] # field mapping dicionary weather --> pvlib
if (weather.SQLTable == 'dwd_s'
): # we want be able to distinguish MOSMIX_L and _S data
self.SQLTable = self._cfg.lower() + '_s'
except AttributeError: # we only have weather data ... let's try anywah
weatherData = weather
f = {}
for col in weatherData.columns:
f[col] = col
if ('Rad1h' not in weatherData and model not in [
'clearsky', 'clearsky_scaling', 'campbell_norman'
]):
raise Exception(
'ERROR --- weather does not include irradiation data, use cloud based models instead of = '
+ model)
elif (model
not in ['clearsky', 'clearsky_scaling', 'campbell_norman']):
ghi = np.array(
weatherData['Rad1h'] *
0.2777778) # convert to Rad1h [kJ/m^2] to Wh/m^2
if (model
not in ['clearsky', 'clearsky_scaling', 'campbell_norman'
]): # we don't need this for cloud models ...
solar_position = self._location.get_solarposition(
times=weatherData.index,
pressure=weatherData[f['pressure']],
temperature=weatherData[f['temp_air']] - 273.15)
cosSZA = np.cos(solar_position['zenith'] * np.pi / 180)
if (model == 'disc' or model == 'dirint' or model == 'dirindex'):
if (model == 'disc'):
disc = pvlib.irradiance.disc(
ghi=
ghi, # returns dataframe with columns = ['dni', 'kt', 'airmass']
solar_zenith=solar_position['zenith'],
datetime_or_doy=weatherData.index,
pressure=weatherData[f['pressure']])
dni = np.array(disc['dni'])
kt = np.array(disc['kt'])
elif (model == 'dirint'):
dni = pvlib.irradiance.dirint(
ghi=ghi, # returns array
solar_zenith=solar_position['zenith'],
times=weatherData.index,
temp_dew=weatherData[f['temp_dew']] - 273.15)
else:
clearsky = self._location.get_clearsky(
weatherData.
index, # calculate clearsky ghi, dni, dhi for times
model='ineichen')
dni = pvlib.irradiance.dirindex(
ghi=ghi, # returns array
ghi_clearsky=clearsky['ghi'],
dni_clearsky=clearsky['dni'],
zenith=solar_position['zenith'],
times=weatherData.index,
pressure=weatherData[f['pressure']],
temp_dew=weatherData[f['temp_dew']] - 273.15)
dhi = ghi - dni * cosSZA
elif (model == 'erbs' or model == 'erbs_kt'):
if (model == 'erbs'):
erbs = pvlib.irradiance.erbs(
ghi=
ghi, # returns dataframe with columns ['dni', 'dhi', 'kt']
zenith=solar_position['zenith'],
datetime_or_doy=weatherData.index)
else: # 'erbs_kt', needs modification in pvlib.irradiance.erbs
try:
erbs = pvlib.irradiance.erbs(
ghi=
ghi, # returns dataframe with columns ['dni', 'dhi', 'kt']
zenith=solar_position['zenith'],
datetime_or_doy=weatherData.index,
kt=weatherData['RRad1'] /
100) # = kt, in range 0 .. 100
except Exception as e:
print(
"getIrradiance: ERROR --- erbs_kt needs modification to pvlib.irradiance.erbs()"
)
sys.exit(1)
dni = np.array(erbs['dni'])
dhi = np.array(erbs['dhi'])
kt = np.array(erbs['kt'])
elif (model == 'clearsky'):
clearsky_model = self.config[self._cfg].get(
'clearsky_model', 'simplified_solis')
self.irradiance = self._location.get_clearsky(
weatherData.
index, # calculate clearsky ghi, dni, dhi for clearsky
model=clearsky_model)
elif (model == 'clearsky_scaling' or model == 'campbell_norman'):
if model == 'campbell_norman' and self._pvversion == '0.8.0':
raise Exception(
"ERROR --- cloud based irradiance model 'campbell_norman' only supported in pvlib 0.8.1 and higher"
)
fcModel = ForecastModel(
'dummy', 'dummy',
'dummy') # only needed to call methods below
fcModel.set_location(latitude=self._location.latitude,
longitude=self._location.longitude,
tz=self._location.tz)
self.irradiance = fcModel.cloud_cover_to_irradiance(
weatherData[f['clouds']], how=model)
else:
raise Exception(
"ERROR --- incorrect irradiance model called: " + model)
except Exception as e:
print("getIrradiance: " + str(e))
sys.exit(1)
if (model != 'clearsky' and model != 'clearsky_scaling'
and model != 'campbell_norman'):
self.irradiance = pd.DataFrame(data=[ghi, dni, dhi]).T
self.irradiance.index = weatherData.index
self.irradiance.columns = ['ghi', 'dni', 'dhi']
if (model == 'disc' or model == 'erbs'):
self.irradiance['kt'] = kt
self.irradiance_model = model
try:
self.irradiance = pd.concat([
weatherData[f['temp_air']] - 273.15,
weatherData[f['wind_speed']], self.irradiance
],
axis=1)
self.irradiance.rename(columns={
f['temp_air']: 'temp_air',
f['wind_speed']: 'wind_speed'
},
inplace=True)
self._cloud_cover_param = f['clouds']
except:
pass
def runModel(self, weather: Forecast, model, modelLst='all'):
"""Run one PV simulation model (named in self.pv_model, set in getIrradiance())
Weather data is inherited from prior call to getIrradiance() call
Populates self.sim_result pandas dataframe with simulation results"""
if modelLst is not None:
if modelLst != 'all' and model != modelLst: # we have an explict list of models to calculate
modelLst = modelLst.replace(" ", "")
models = modelLst.split(",")
if model not in models: # request was for something else ...
return None
try:
self.getIrradiance(weather, model)
self._mc.run_model(self.irradiance)
cols = ['ghi', 'dni', 'dhi']
if 'kt' in self.irradiance:
cols.append('kt')
if (self.pv_model == 'PVWatts'):
self.DataTable = pd.concat(
[self._mc.dc, self._mc.ac, self.irradiance[cols]], axis=1)
else: # CEC
self.DataTable = pd.concat(
[self._mc.dc.p_mp, self._mc.ac, self.irradiance[cols]],
axis=1)
m = self.irradiance_model
if (m == 'clearsky_scaling' or m == 'campbell_norman'):
m = m + '_' + self._cloud_cover_param
if (m == 'disc' or m == 'erbs'):
self.DataTable.columns = [
'dc_' + m, 'ac_' + m, 'ghi_' + m, 'dni_' + m, 'dhi_' + m,
'kt_' + m
]
else:
self.DataTable.columns = [
'dc_' + m, 'ac_' + m, 'ghi_' + m, 'dni_' + m, 'dhi_' + m
]
self.InfluxFields.append('dc_' + m)
return self.DataTable
except Exception as e:
print("runModel: " + str(e))
sys.exit(1)
def run_allModels(self, weather: Forecast, modelLst='all'):
"""Run all implemented models (default). Alternatively, 'modelLst' can contain a
comma separated list of valid models (see self.runModel()) to be calculated
Populates self.DataTable pandas dataframe with all simulation results"""
dfList = [] # list of calculated models
if ('Rad1h' in weather.DataTable): # ---- irrandiance based models
dfList.append(self.runModel(weather, 'disc', modelLst))
dfList.append(self.runModel(weather, 'dirint', modelLst))
dfList.append(self.runModel(weather, 'dirindex', modelLst))
dfList.append(self.runModel(weather, 'erbs', modelLst))
if 'RRad1' in weather.DataTable and self._allow_experimental:
dfList.append(self.runModel(weather, 'erbs_kt', modelLst))
dfList.append(self.runModel(weather, 'clearsky_scaling',
modelLst)) # ---- cloud based models
if self._pvversion >= '0.8.1': # deprecated model 'liujordan' not implemented
dfList.append(self.runModel(weather, 'campbell_norman', modelLst))
dfList.append(self.runModel(weather, 'clearsky', modelLst))
dfList.append(
self._mc.solar_position.zenith) # ---- add solar position
self.DataTable = pd.concat(dfList, axis=1)
drop = []
haveGHI = False
for col in self.DataTable:
if 'ghi' in col and not (col.startswith('ghi_clearsky')
or col.startswith('ghi_campbell')):
if not haveGHI:
self.DataTable.rename(
columns={col: 'ghi'}, inplace=True
) # rename first GHI field as GHI, since this is input and hence same for all models
haveGHI = True
else:
drop.append(col)
elif col == 'kt_erbs_kt':
drop.append(
col) # redundant as kt is input to (experimental) erbs_kt
if (len(drop) > 0): self.DataTable = self.DataTable.drop(drop, axis=1)
def writeCSV(self, csvName): # write self.weatherData to .csv file
"""Store simulated PV power in .csv file"""
path = self.config[self._cfg].get('storePath')
fName = re.sub(r'\.kml$', '_sim.csv.gz', csvName)
self.DataTable.to_csv(path + "/" + fName, compression='gzip')
return ()
class ForecastModel(object):
"""
An object for querying and holding forecast model information for
use within the pvlib library.
Simplifies use of siphon library on a THREDDS server.
Parameters
----------
model_type: string
UNIDATA category in which the model is located.
model_name: string
Name of the UNIDATA forecast model.
set_type: string
Model dataset type.
Attributes
----------
access_url: string
URL specifying the dataset from data will be retrieved.
base_tds_url : string
The top level server address
catalog_url : string
The url path of the catalog to parse.
data: pd.DataFrame
Data returned from the query.
data_format: string
Format of the forecast data being requested from UNIDATA.
dataset: Dataset
Object containing information used to access forecast data.
dataframe_variables: list
Model variables that are present in the data.
datasets_list: list
List of all available datasets.
fm_models: Dataset
TDSCatalog object containing all available
forecast models from UNIDATA.
fm_models_list: list
List of all available forecast models from UNIDATA.
latitude: list
A list of floats containing latitude values.
location: Location
A pvlib Location object containing geographic quantities.
longitude: list
A list of floats containing longitude values.
lbox: boolean
Indicates the use of a location bounding box.
ncss: NCSS object
NCSS
model_name: string
Name of the UNIDATA forecast model.
model: Dataset
A dictionary of Dataset object, whose keys are the name of the
dataset's name.
model_url: string
The url path of the dataset to parse.
modelvariables: list
Common variable names that correspond to queryvariables.
query: NCSS query object
NCSS object used to complete the forecast data retrival.
queryvariables: list
Variables that are used to query the THREDDS Data Server.
time: DatetimeIndex
Time range.
variables: dict
Defines the variables to obtain from the weather
model and how they should be renamed to common variable names.
units: dict
Dictionary containing the units of the standard variables
and the model specific variables.
vert_level: float or integer
Vertical altitude for query data.
"""
access_url_key = 'NetcdfSubset'
catalog_url = 'http://thredds.ucar.edu/thredds/catalog.xml'
base_tds_url = catalog_url.split('/thredds/')[0]
data_format = 'netcdf'
vert_level = 100000
units = {
'temp_air': 'C',
'wind_speed': 'm/s',
'ghi': 'W/m^2',
'ghi_raw': 'W/m^2',
'dni': 'W/m^2',
'dhi': 'W/m^2',
'total_clouds': '%',
'low_clouds': '%',
'mid_clouds': '%',
'high_clouds': '%'}
def __init__(self, model_type, model_name, set_type):
self.model_type = model_type
self.model_name = model_name
self.set_type = set_type
self.catalog = TDSCatalog(self.catalog_url)
self.fm_models = TDSCatalog(self.catalog.catalog_refs[model_type].href)
self.fm_models_list = sorted(list(self.fm_models.catalog_refs.keys()))
try:
model_url = self.fm_models.catalog_refs[model_name].href
except ParseError:
raise ParseError(self.model_name + ' model may be unavailable.')
try:
self.model = TDSCatalog(model_url)
except HTTPError:
try:
self.model = TDSCatalog(model_url)
except HTTPError:
raise HTTPError(self.model_name + ' model may be unavailable.')
self.datasets_list = list(self.model.datasets.keys())
self.set_dataset()
def __repr__(self):
return '{}, {}'.format(self.model_name, self.set_type)
def set_dataset(self):
'''
Retrieves the designated dataset, creates NCSS object, and
creates a NCSS query object.
'''
keys = list(self.model.datasets.keys())
labels = [item.split()[0].lower() for item in keys]
if self.set_type == 'best':
self.dataset = self.model.datasets[keys[labels.index('best')]]
elif self.set_type == 'latest':
self.dataset = self.model.datasets[keys[labels.index('latest')]]
elif self.set_type == 'full':
self.dataset = self.model.datasets[keys[labels.index('full')]]
self.access_url = self.dataset.access_urls[self.access_url_key]
self.ncss = NCSS(self.access_url)
self.query = self.ncss.query()
def set_query_latlon(self):
'''
Sets the NCSS query location latitude and longitude.
'''
if (isinstance(self.longitude, list) and
isinstance(self.latitude, list)):
self.lbox = True
# west, east, south, north
self.query.lonlat_box(self.latitude[0], self.latitude[1],
self.longitude[0], self.longitude[1])
else:
self.lbox = False
self.query.lonlat_point(self.longitude, self.latitude)
def set_location(self, time, latitude, longitude):
'''
Sets the location for the query.
Parameters
----------
time: datetime or DatetimeIndex
Time range of the query.
'''
if isinstance(time, datetime.datetime):
tzinfo = time.tzinfo
else:
tzinfo = time.tz
if tzinfo is None:
self.location = Location(latitude, longitude)
else:
self.location = Location(latitude, longitude, tz=tzinfo)
def get_data(self, latitude, longitude, start, end,
vert_level=None, query_variables=None,
close_netcdf_data=True):
"""
Submits a query to the UNIDATA servers using Siphon NCSS and
converts the netcdf data to a pandas DataFrame.
Parameters
----------
latitude: float
The latitude value.
longitude: float
The longitude value.
start: datetime or timestamp
The start time.
end: datetime or timestamp
The end time.
vert_level: None, float or integer
Vertical altitude of interest.
variables: None or list
If None, uses self.variables.
close_netcdf_data: bool
Controls if the temporary netcdf data file should be closed.
Set to False to access the raw data.
Returns
-------
forecast_data : DataFrame
column names are the weather model's variable names.
"""
if vert_level is not None:
self.vert_level = vert_level
if query_variables is None:
self.query_variables = list(self.variables.values())
else:
self.query_variables = query_variables
self.latitude = latitude
self.longitude = longitude
self.set_query_latlon() # modifies self.query
self.set_location(start, latitude, longitude)
self.start = start
self.end = end
self.query.time_range(self.start, self.end)
self.query.vertical_level(self.vert_level)
self.query.variables(*self.query_variables)
self.query.accept(self.data_format)
self.netcdf_data = self.ncss.get_data(self.query)
# might be better to go to xarray here so that we can handle
# higher dimensional data for more advanced applications
self.data = self._netcdf2pandas(self.netcdf_data, self.query_variables)
if close_netcdf_data:
self.netcdf_data.close()
return self.data
def process_data(self, data, **kwargs):
"""
Defines the steps needed to convert raw forecast data
into processed forecast data. Most forecast models implement
their own version of this method which also call this one.
Parameters
----------
data: DataFrame
Raw forecast data
Returns
-------
data: DataFrame
Processed forecast data.
"""
data = self.rename(data)
return data
def get_processed_data(self, *args, **kwargs):
"""
Get and process forecast data.
Parameters
----------
*args: positional arguments
Passed to get_data
**kwargs: keyword arguments
Passed to get_data and process_data
Returns
-------
data: DataFrame
Processed forecast data
"""
return self.process_data(self.get_data(*args, **kwargs), **kwargs)
def rename(self, data, variables=None):
"""
Renames the columns according the variable mapping.
Parameters
----------
data: DataFrame
variables: None or dict
If None, uses self.variables
Returns
-------
data: DataFrame
Renamed data.
"""
if variables is None:
variables = self.variables
return data.rename(columns={y: x for x, y in variables.items()})
def _netcdf2pandas(self, netcdf_data, query_variables):
"""
Transforms data from netcdf to pandas DataFrame.
Parameters
----------
data: netcdf
Data returned from UNIDATA NCSS query.
query_variables: list
The variables requested.
Returns
-------
pd.DataFrame
"""
# set self.time
try:
time_var = 'time'
self.set_time(netcdf_data.variables[time_var])
except KeyError:
# which model does this dumb thing?
time_var = 'time1'
self.set_time(netcdf_data.variables[time_var])
data_dict = {key: data[:].squeeze() for key, data in
netcdf_data.variables.items() if key in query_variables}
return pd.DataFrame(data_dict, index=self.time)
def set_time(self, time):
'''
Converts time data into a pandas date object.
Parameters
----------
time: netcdf
Contains time information.
Returns
-------
pandas.DatetimeIndex
'''
times = num2date(time[:].squeeze(), time.units)
self.time = pd.DatetimeIndex(pd.Series(times), tz=self.location.tz)
def cloud_cover_to_ghi_linear(self, cloud_cover, ghi_clear, offset=35,
**kwargs):
"""
Convert cloud cover to GHI using a linear relationship.
0% cloud cover returns ghi_clear.
100% cloud cover returns offset*ghi_clear.
Parameters
----------
cloud_cover: numeric
Cloud cover in %.
ghi_clear: numeric
GHI under clear sky conditions.
offset: numeric
Determines the minimum GHI.
kwargs
Not used.
Returns
-------
ghi: numeric
Estimated GHI.
References
----------
Larson et. al. "Day-ahead forecasting of solar power output from
photovoltaic plants in the American Southwest" Renewable Energy
91, 11-20 (2016).
"""
offset = offset / 100.
cloud_cover = cloud_cover / 100.
ghi = (offset + (1 - offset) * (1 - cloud_cover)) * ghi_clear
return ghi
def cloud_cover_to_irradiance_clearsky_scaling(self, cloud_cover,
method='linear',
**kwargs):
"""
Estimates irradiance from cloud cover in the following steps:
1. Determine clear sky GHI using Ineichen model and
climatological turbidity.
2. Estimate cloudy sky GHI using a function of
cloud_cover e.g.
:py:meth:`~ForecastModel.cloud_cover_to_ghi_linear`
3. Estimate cloudy sky DNI using the DISC model.
4. Calculate DHI from DNI and DHI.
Parameters
----------
cloud_cover : Series
Cloud cover in %.
method : str
Method for converting cloud cover to GHI.
'linear' is currently the only option.
**kwargs
Passed to the method that does the conversion
Returns
-------
irrads : DataFrame
Estimated GHI, DNI, and DHI.
"""
solpos = self.location.get_solarposition(cloud_cover.index)
cs = self.location.get_clearsky(cloud_cover.index, model='ineichen',
solar_position=solpos)
method = method.lower()
if method == 'linear':
ghi = self.cloud_cover_to_ghi_linear(cloud_cover, cs['ghi'],
**kwargs)
else:
raise ValueError('invalid method argument')
dni = disc(ghi, solpos['zenith'], cloud_cover.index)['dni']
dhi = ghi - dni * np.cos(np.radians(solpos['zenith']))
irrads = pd.DataFrame({'ghi': ghi, 'dni': dni, 'dhi': dhi}).fillna(0)
return irrads
def cloud_cover_to_transmittance_linear(self, cloud_cover, offset=0.75,
**kwargs):
"""
Convert cloud cover to atmospheric transmittance using a linear
model.
0% cloud cover returns offset.
100% cloud cover returns 0.
Parameters
----------
cloud_cover : numeric
Cloud cover in %.
offset : numeric
Determines the maximum transmittance.
kwargs
Not used.
Returns
-------
ghi : numeric
Estimated GHI.
"""
transmittance = ((100.0 - cloud_cover) / 100.0) * 0.75
return transmittance
def cloud_cover_to_irradiance_liujordan(self, cloud_cover, **kwargs):
"""
Estimates irradiance from cloud cover in the following steps:
1. Determine transmittance using a function of cloud cover e.g.
:py:meth:`~ForecastModel.cloud_cover_to_transmittance_linear`
2. Calculate GHI, DNI, DHI using the
:py:func:`pvlib.irradiance.liujordan` model
Parameters
----------
cloud_cover : Series
Returns
-------
irradiance : DataFrame
Columns include ghi, dni, dhi
"""
# in principle, get_solarposition could use the forecast
# pressure, temp, etc., but the cloud cover forecast is not
# accurate enough to justify using these minor corrections
solar_position = self.location.get_solarposition(cloud_cover.index)
dni_extra = extraradiation(cloud_cover.index)
airmass = self.location.get_airmass(cloud_cover.index)
transmittance = self.cloud_cover_to_transmittance_linear(cloud_cover,
**kwargs)
irrads = liujordan(solar_position['apparent_zenith'],
transmittance, airmass['airmass_absolute'],
dni_extra=dni_extra)
irrads = irrads.fillna(0)
return irrads
def cloud_cover_to_irradiance(self, cloud_cover, how='clearsky_scaling',
**kwargs):
"""
Convert cloud cover to irradiance. A wrapper method.
Parameters
----------
cloud_cover : Series
how : str
Selects the method for conversion. Can be one of
clearsky_scaling or liujordan.
**kwargs
Passed to the selected method.
Returns
-------
irradiance : DataFrame
Columns include ghi, dni, dhi
"""
how = how.lower()
if how == 'clearsky_scaling':
irrads = self.cloud_cover_to_irradiance_clearsky_scaling(
cloud_cover, **kwargs)
elif how == 'liujordan':
irrads = self.cloud_cover_to_irradiance_liujordan(
cloud_cover, **kwargs)
else:
raise ValueError('invalid how argument')
return irrads
def kelvin_to_celsius(self, temperature):
"""
Converts Kelvin to celsius.
Parameters
----------
temperature: numeric
Returns
-------
temperature: numeric
"""
return temperature - 273.15
def isobaric_to_ambient_temperature(self, data):
"""
Calculates temperature from isobaric temperature.
Parameters
----------
data: DataFrame
Must contain columns pressure, temperature_iso,
temperature_dew_iso. Input temperature in K.
Returns
-------
temperature : Series
Temperature in K
"""
P = data['pressure'] / 100.0
Tiso = data['temperature_iso']
Td = data['temperature_dew_iso'] - 273.15
# saturation water vapor pressure
e = 6.11 * 10**((7.5 * Td) / (Td + 273.3))
# saturation water vapor mixing ratio
w = 0.622 * (e / (P - e))
T = Tiso - ((2.501 * 10.**6) / 1005.7) * w
return T
def uv_to_speed(self, data):
"""
Computes wind speed from wind components.
Parameters
----------
data : DataFrame
Must contain the columns 'wind_speed_u' and 'wind_speed_v'.
Returns
-------
wind_speed : Series
"""
wind_speed = np.sqrt(data['wind_speed_u']**2 + data['wind_speed_v']**2)
return wind_speed
def gust_to_speed(self, data, scaling=1/1.4):
"""
Computes standard wind speed from gust.
Very approximate and location dependent.
Parameters
----------
data : DataFrame
Must contain the column 'wind_speed_gust'.
Returns
-------
wind_speed : Series
"""
wind_speed = data['wind_speed_gust'] * scaling
return wind_speed
class LocalRE(object):
forecast_height = 10 # for DarkSky API
def __init__(
self,
wind_turbines: list = [],
pv_arrays: list = [],
latitude: float = 57.6568,
longitude: float = -3.5818,
altitude: float = 10,
roughness_length: float = 0.15, # roughness length (bit of a guess)
hellman_exp: float = 0.2):
""" Set up the renewable energy generation
"""
# This needs to be repeated in every forecast
self.roughness_length = roughness_length
# Initialise empty forecast dataframe, just so nothing complains
self.wind_forecast = pd.DataFrame()
self.pv_forecast = pd.DataFrame()
# Wind turbine(s)
turbines = []
for turbine in wind_turbines:
turbines.append({
'wind_turbine':
WindTurbine(turbine['name'],
turbine['hub_height'],
nominal_power=turbine['nominal_power'],
rotor_diameter=turbine['rotor_diameter'],
power_curve=turbine['power_curve']),
'number_of_turbines':
turbine['qty']
})
local_wind_farm = WindFarm('Local windfarm', turbines,
[latitude, longitude])
# TODO - check for learned local data & overwrite power_curve
self.wind_modelchain = TurbineClusterModelChain(
local_wind_farm,
smoothing=False,
hellman_exp=hellman_exp,
)
# Initialise PV models
self.pv_location = Location(latitude=latitude,
longitude=longitude,
altitude=altitude)
# Now set up the PV array & system.
cec_pv_model_params = pvlib.pvsystem.retrieve_sam('CECMod')
sandia_pv_model_params = pvlib.pvsystem.retrieve_sam('SandiaMod')
cec_inverter_model_params = pvlib.pvsystem.retrieve_sam('CECInverter')
adr_inverter_model_params = pvlib.pvsystem.retrieve_sam('ADRInverter')
self.pv_modelchains = {}
for pv_array in pv_arrays:
# Try to find the module names in the libraries
if pv_array['module_name'] in cec_pv_model_params:
pv_array['module_parameters'] = cec_pv_model_params[
pv_array['module_name']]
elif pv_array['module_name'] in sandia_pv_model_params:
pv_array['module_parameters'] = sandia_pv_model_params[
pv_array['module_name']]
else:
raise RenewablesException('Could not retrieve PV module data')
# Do the same with the inverter(s)
if pv_array['inverter_name'] in cec_inverter_model_params:
pv_array['inverter_parameters'] = cec_inverter_model_params[
pv_array['inverter_name']]
elif pv_array['inverter_name'] in adr_inverter_model_params:
pv_array['inverter_parameters'] = adr_inverter_model_params[
pv_array['inverter_name']]
else:
raise RenewablesException('Could not retrieve PV module data')
self.pv_modelchains[pv_array['name']] = ModelChain(
PVSystem(**pv_array),
self.pv_location,
aoi_model='physical',
spectral_model='no_loss')
def make_generation_forecasts(self, forecast):
""" Makes generation forecast data from the supplied Dark Sky forecast
Arguments:
forecast {pandas.DataFrame} -- DarkSky originated forecast
"""
self.pv_forecast = self._make_pv_forecast(forecast)
self.wind_forecast = self._make_wind_forecast(forecast)
def _make_pv_forecast(self, forecast) -> pd.DataFrame:
"""Compile the forecast required for PV generation prediction
Uses pvlib to generate solar irradiance predictions.
Arguments:
forecast {pandas.DataFrame} -- DarkSky originated forecast
"""
# Annoyingly, the PV & wind libraries want temperature named differently
pv_forecast = forecast.rename(columns={
'temperature': 'air_temp',
'windSpeed': 'wind_speed',
})
# Use PV lib to get insolation based on the cloud cover reported here
model = GFS()
# Next up, we get hourly solar irradiance using interpolated cloud cover
# We can get this from the clearsky GHI...
if tables in sys.modules:
# We can use Ineichen clear sky model (uses pytables for turbidity)
clearsky = self.pv_location.get_clearsky(pv_forecast.index)
else:
# We can't, so use 'Simplified Solis'
clearsky = self.pv_location.get_clearsky(pv_forecast.index,
model='simplified_solis')
# ... and by knowledge of where the sun is
solpos = self.pv_location.get_solarposition(pv_forecast.index)
ghi = model.cloud_cover_to_ghi_linear(pv_forecast['cloudCover'] * 100,
clearsky['ghi'])
dni = disc(ghi, solpos['zenith'], pv_forecast.index)['dni']
dhi = ghi - dni * np.cos(np.radians(solpos['zenith']))
# Whump it all together and we have our forecast!
pv_forecast['dni'] = dni
pv_forecast['dhi'] = dhi
pv_forecast['ghi'] = ghi
return pv_forecast
def _make_wind_forecast(self, forecast) -> pd.DataFrame:
"""Creates forecast needed for wind generation prediction
Creates renamed multidimensional columns needed for the windpowerlib
system.
Arguments:
forecast {pandas.DataFrame} -- DarkSky originated forecast
"""
# Easiest to build multiindexes up one by one.
columns_index = pd.MultiIndex.from_tuples([('wind_speed', 10),
('temperature', 10),
('pressure', 10),
('roughness_length', 0),
('wind_bearing', 10)])
wind_forecast = pd.DataFrame(index=forecast.index.copy(),
columns=columns_index)
wind_forecast.loc[:, ('wind_speed', 10)] = forecast['windSpeed'].loc[:]
wind_forecast.loc[:,
('temperature', 10)] = forecast['temperature'].loc[:]
wind_forecast.loc[:, ('pressure', 10)] = forecast['pressure'].loc[:]
wind_forecast.loc[:, ('wind_bearing',
10)] = forecast['windBearing'].loc[:]
wind_forecast.loc[:, ('roughness_length', 0)] = self.roughness_length
return wind_forecast
def predict_generation(self, reserved_wind_consumption=0) -> pd.DataFrame:
""" Predict electricity generated from forecast
Will use the timestamp index of the forecast property to estimate
instantaneous electricity generation. Returns table giving amounts in
kWh.
Arguments:
reserved_wind_consumption {float} - constant amount that is assumed
to be required from wind generation to meet other local need
"""
prediction = pd.DataFrame(index=self.pv_forecast.index.copy())
# First up - PV
# Create a total gen column of zeros
prediction['PV_AC_TOTAL'] = 0
for pv_array, pv_model in self.pv_modelchains.items():
pv_model.run_model(prediction.index, self.pv_forecast)
output_column_name = 'PV_AC_' + pv_array
prediction[output_column_name] = pv_model.ac
# Add to the total column
prediction['PV_AC_TOTAL'] = prediction['PV_AC_TOTAL'] + pv_model.ac
# Next - wind power.
self.wind_modelchain.run_model(self.wind_forecast)
prediction['WIND_AC'] = self.wind_modelchain.power_output
# Convert everything into kWh
prediction = prediction * 0.001
prediction['available_wind'] = prediction[
'WIND_AC'] - reserved_wind_consumption
prediction['available_wind'][prediction['available_wind'] < 0] = 0
prediction['total'] = prediction['WIND_AC'] + prediction['PV_AC_TOTAL']
prediction['surplus'] = prediction['available_wind'] + prediction[
'PV_AC_TOTAL']
prediction['surplus'][prediction['surplus'] < 0] = 0
return prediction