refactor: calculate marginal cost via linearized quadratic (Breakthro…

…ugh-Energy#603)

powersimdata/input/export_data.py

@@ -77,7 +77,6 @@
         "rename": {
             "startup": "startup_cost",
             "shutdown": "shutdown_cost",
-            "c1": "marginal_cost",
         }
     },
     "branch": {
@@ -397,6 +396,12 @@ def export_to_pypsa(
 
     gencost = grid.gencost["before"]
     gencost = gencost.rename(columns=pypsa_const["cost"]["rename"])
+    # Linearize quadratic curves as applicable
+    fixed = grid.plant["Pmin"] == grid.plant["Pmax"]
+    linearized = gencost.loc[~fixed, "c1"] + gencost.loc[~fixed, "c2"] * (
+        grid.plant.loc[~fixed, "Pmax"] + grid.plant.loc[~fixed, "Pmin"]
+    )
+    gencost["marginal_cost"] = linearized.combine_first(gencost["c1"])
     gencost = gencost[pypsa_const["cost"]["rename"].values()]
 
     carriers = pd.DataFrame(index=generators.carrier.unique(), dtype=object)