fixing legacy lightsim2grid compat

.circleci/config.yml

@@ -178,7 +178,7 @@ jobs:
                command: |
                    source venv_test/bin/activate
                    python -m pip install -U pip setuptools wheel
-                   python -m pip install -U lightsim2grid==0.5.3 gymnasium "numpy<1.22" "pandapower<2.14.9"
+                   python -m pip install -U lightsim2grid==0.5.3 gymnasium "numpy<1.22"
             - run:
                command: |
                    source venv_test/bin/activate
@@ -205,7 +205,7 @@ jobs:
                command: |
                    source venv_test/bin/activate
                    python -m pip install -U pip setuptools wheel
-                   python -m pip install -U lightsim2grid==0.6.0 gymnasium
+                   python -m pip install -U lightsim2grid==0.6.0 gymnasium "numpy<1.22"
             - run:
                command: |
                    source venv_test/bin/activate

grid2op/Backend/pandaPowerBackend.py

@@ -17,13 +17,17 @@
 
 import pandapower as pp
 import scipy
+# check that pandapower does not introduce some 
+from packaging import version
 
 import grid2op
 from grid2op.dtypes import dt_int, dt_float, dt_bool
 from grid2op.Action import BaseAction
 from grid2op.Exceptions import BackendError
 from grid2op.Backend.backend import Backend
 
+MIN_LS_VERSION_VM_PU = version.parse("0.6.0")
+
 try:
     import numba
     NUMBA_ = True
@@ -544,6 +548,23 @@ def load_grid(self,
         self._in_service_storage_cold_id = int((self._grid.storage.columns == "in_service").nonzero()[0][0])
         self.comp_time = 0.
 
+        # hack for backward compat with oldest lightsim2grid version
+        try:
+            import lightsim2grid
+            if version.parse(lightsim2grid.__version__) < MIN_LS_VERSION_VM_PU:
+                warnings.warn("You are using a really old version of lightsim2grid. Consider upgrading.")
+                if "_options" in self._grid and "init_vm_pu" in self._grid["_options"]:
+                    try:
+                        float(self._grid["_options"]["init_vm_pu"])
+                    except ValueError as exc_:
+                        # we delete it because lightsim2grid uses it
+                        # to init its internal "GridModel" and did not check that
+                        # this is a float until MIN_LS_VERSION_VM_PU
+                        del self._grid["_options"]["init_vm_pu"]
+        except ImportError:
+            # lightsim2grid is not installed, so no risk to contaminate it
+            pass
+
     def _aux_run_pf_init(self):
         """run a powerflow when the file is being loaded. This is called three times for each call to "load_grid" """
         with warnings.catch_warnings():