update line rating(documentation, bundles)

Snakefile

@@ -233,7 +233,7 @@ rule add_electricity:
         base_network = "networks/base.nc",
         tech_costs=COSTS,
         regions="resources/regions_onshore.geojson",
-        line_rating="resources/line_rating.nc" if config['lines'].get('line_rating', False) else None,
+        line_rating="resources/line_rating.nc" if config['lines'].get('line_rating', False) else "networks/base.nc",
         powerplants='resources/powerplants.csv',
         hydro_capacities='data/bundle/hydro_capacities.csv',
         geth_hydro_capacities='data/geth2015_hydro_capacities.csv',

scripts/build_line_rating.py

@@ -11,8 +11,9 @@ Relevant Settings
 
 .. code:: yaml
 
-    lines_t:
+    lines:
-        s_max_pu
+        cutout:
+        line_rating:
 
 
 .. seealso::
@@ -26,7 +27,7 @@ Inputs
 Outputs
 -------
 
-- ``networks/base_with_line_rating.nc``
+- ``resources/line_rating.nc``
 
 
 Description
@@ -58,9 +59,41 @@ import geopandas as gpd
 from shapely.geometry import Point, LineString as Line
 import atlite
 import xarray as xr
+import re
 
+def calculate_resistance(T, R_ref, T_ref=20, alpha=0.00403):
+    """
+    Calculates the resistance at other temperatures than the reference temperature.
+
+    Parameters
+    ----------
+    T : Temperature at which resistance is calculated in [°C] or [K]
+    R_ref : Resistance at reference temperature in [Ohm] or [Ohm/Per Length Unit]
+    T_ref : Reference temperature in [°C] or [K]
+    alpha: Temperature coefficient in [1/K]
+        Defaults are:
+            * T_ref : 20 °C
+            * alpha : 0.00403 1/K
+
+    Returns
+    -------
+    Resistance of at given temperature.
+    """
+    R=R_ref+(1+alpha*(T-T_ref))
+    return R
 
 def calculate_line_rating(n):
+    """
+    Calculates the maximal allowed power flow in each line for each time step considering the maximal temperature.
+
+    Parameters
+    ----------
+    n : pypsa.Network object containing information on grid
+    
+    Returns
+    -------
+    xarray DataArray object with maximal power.
+    """
     relevant_lines=n.lines[(n.lines['underground']==False) & (n.lines['under_construction']==False)] 
     buses = relevant_lines[["bus0", "bus1"]].values
     x = n.buses.x
@@ -71,8 +104,13 @@ def calculate_line_rating(n):
     if relevant_lines.r_pu.eq(0).all():
         #Overwrite standard line resistance with line resistance obtained from line type 
         relevant_lines["r_pu"]=relevant_lines.join(n.line_types["r_per_length"], on=["type"])['r_per_length']/1000 #in meters
-    Imax=cutout.line_rating(shapes, relevant_lines.r_pu)
+        #Set default number of bundles per line
-    da = xr.DataArray(data=np.sqrt(3) * Imax * relevant_lines["v_nom"].values.reshape(-1,1) * relevant_lines["num_parallel"].values.reshape(-1,1)/1e3, #in mW
+        relevant_lines["n_bundle"]=1
+        #If line type with bundles is given retrieve number of conductors per bundle
+        if relevant_lines["type"].str.contains("bundle").all():
+            relevant_lines["n_bundle"]=relevant_lines["type"].apply(lambda x: int(re.findall(r"(\d+)-bundle", x)[0]))
+    Imax=cutout.line_rating(shapes, relevant_lines.r_pu, D=0.0218 ,Ts=353 , epsilon=0.8, alpha=0.8)
+    da = xr.DataArray(data=np.sqrt(3) * Imax * relevant_lines["v_nom"].values.reshape(-1,1) * np.sqrt(relevant_lines["n_bundle"].values.reshape(-1,1)) * relevant_lines["num_parallel"].values.reshape(-1,1)/1e3, #in mW
                       attrs=dict(description="Maximal possible power in MW for given line considering line rating"))
     return da