adding possibility to init lightsim2grid by providing desired slack name

CHANGELOG.rst

@@ -22,8 +22,10 @@ Change Log
 --------------------
 - [FIXED] CI was broken after migration to artifact v4, set it back to v3 
   (and make the names of the folder clearer)
-- [FIXED] CI when using latest pandapower version (2.14)
+- [FIXED] CI when using latest pandapower version (2.14) which broke some previous tests
 - [IMPROVED] remove some compilation warnings for clang
+- [IMPROVED] possibility to specify generator used as slack by its name when initializing
+  from `pypowsybl`.
 
 [0.8.1] 2024-03-26
 --------------------

lightsim2grid/gridmodel/from_pypowsybl.py

@@ -10,6 +10,7 @@
 import numpy as np
 import pandas as pd
 import pypowsybl as pypo
+from typing import Union
 
 from lightsim2grid_cpp import GridModel
 
@@ -36,7 +37,7 @@ def _aux_get_bus(bus_df, df, conn_key="connected", bus_key="bus_id"):
 
 
 def init(net : pypo.network,
-         gen_slack_id: int = None,
+         gen_slack_id: Union[int, str] = None,
          slack_bus_id: int = None,
          sn_mva = 100.,
          sort_index=True,
@@ -260,7 +261,17 @@ def init(net : pypo.network,
     elif gen_slack_id is not None:
         if slack_bus_id is not None:
             raise RuntimeError(f"You provided both gen_slack_id and slack_bus_id which is not possible.")
-        model.add_gen_slackbus(gen_slack_id, 1.)
+
+        if isinstance(gen_slack_id, str):
+            gen_slack_id_int = int((df_gen.index == gen_slack_id).nonzero()[0][0])
+        else:
+            try:
+                gen_slack_id_int = int(gen_slack_id)
+            except Exception:
+                raise RuntimeError("'slack_bus_id' should be either an int or a generator names")
+            if gen_slack_id_int != gen_slack_id:
+                raise RuntimeError("'slack_bus_id' should be either an int or a generator names")
+        model.add_gen_slackbus(gen_slack_id_int, 1.)
     elif slack_bus_id is not None:
         gen_bus = np.array([el.bus_id for el in model.get_generators()])
         gen_is_conn_slack = gen_bus == model._orig_to_ls[slack_bus_id]

lightsim2grid/lightSimBackend.py

@@ -556,7 +556,7 @@ def _load_grid_pypowsybl(self, path=None, filename=None):
         grid_tmp = pypow_net.load(full_path)
         gen_slack_id = None
         if "gen_slack_id" in loader_kwargs:
-            gen_slack_id = int(loader_kwargs["gen_slack_id"])
+            gen_slack_id = loader_kwargs["gen_slack_id"]
         self._grid, subs_id = init_pypow(grid_tmp, gen_slack_id=gen_slack_id, sort_index=True, return_sub_id=True)
         (buses_sub_id, gen_sub, load_sub, (lor_sub, tor_sub), (lex_sub, tex_sub), batt_sub, sh_sub, hvdc_sub_from_id, hvdc_sub_to_id) = subs_id
         self.__nb_bus_before = len(self._grid.get_bus_vn_kv())