refactor: use BA as primary interconnect mapper, NERC region as fallback

prereise/gather/griddata/hifld/data_process/generators.py

@@ -374,16 +374,17 @@ def build_plant(bus, substations, kwargs={}):
     substations = substations.loc[set(bus_groupby.groups.keys())]
     epa_ampd_groupby = epa_ampd.groupby(["ORISPL_CODE", "UNITID"])
 
-    # Add information
+    # Add information to generators based on Form 860 Plant table
+    generators = generators.merge(plants, on="Plant Code", suffixes=(None, "_860Plant"))
+    generators.rename(
+        {"Latitude": "lat", "Longitude": "lon", "Zip": "ZIP"}, axis=1, inplace=True
+    )
+    # Map interconnect via BA first (more reliable) then by NERC Region
     generators["interconnect"] = (
-        generators["Plant Code"]
-        .map(plants["NERC Region"])
-        .map(const.nercregion2interconnect)
+        generators["Balancing Authority Code"]
+        .map(const.balancingauthority2interconnect)
+        .combine_first(generators["NERC Region"].map(const.nercregion2interconnect))
     )
-    generators["lat"] = generators["Plant Code"].map(plants["Latitude"])
-    generators["lon"] = generators["Plant Code"].map(plants["Longitude"])
-    generators["ZIP"] = generators["Plant Code"].map(plants["Zip"])
-    generators["state"] = generators["Plant Code"].map(plants["State"])
 
     # Ensure we have Pmax and Pmin for each generator
     generators["Pmax"] = generators[