[bug] DiscreteShuntController controlled bus not updating with create_continuous_bus_index

[garctaedius]

Bug report checklis

• Searched the issues page for similar reports

• Read the relevant sections of the documentation

• Browse the tutorials and tests for usefull code snippets and examples of use

• Reproduced the issue after updating with pip install --upgrade pandapower (or git pull)

• Tried basic troubleshooting (if a bug/error) like restarting the interpreter and checking the pythonpath

Reproducible Example

from pandapower.create import (
    create_bus, 
    create_empty_network,
    create_shunt
)
from pandapower.control import DiscreteShuntController
from pandapower.toolbox import drop_buses, create_continuous_bus_index

#create empty net
net = create_empty_network()

#create buses
bus1 = create_bus(net, vn_kv=20., name="Bus 1")
bus2 = create_bus(net, vn_kv=10., name="Bus 2")
bus3 = create_bus(net, vn_kv=5.,  name="Bus 3")

#create shunt
shunt = create_shunt(net, bus=bus3, q_mvar=0)

#create shunt controller
shunt_controller = DiscreteShuntController(net, shunt, vm_set_pu=1.0)

# Everything works fine
print(net.shunt.loc[shunt].bus == shunt_controller.controlled_bus == 2)  # True

# Now, lets drop bus2 and reindex the buses
drop_buses(net, [bus2])
create_continuous_bus_index(net)

# bus3 now has index 1 (as is expected)
print(net.bus.loc[1]["name"] == "Bus 3")  # True

# The bus for shunt as been appropriately updated
print(net.shunt.loc[shunt].bus == 1)  # True

# However, the controlled bus for the shunt controller has NOT been updated
print(net.shunt.loc[shunt].bus == shunt_controller.controlled_bus)  # FALSE

Issue Description and Traceback

It seems that create_continuous_bus_index does not change the index for the controlled_bus on the DiscreteShuntController. Might also be an issue with the other reindex functions. This I have not tested.

Expected Behavior

For the DiscreteShuntController.controlled_bus to also be updated to the new index when using create_continuous_bus_index. Has to be done manually now.

Installed Versions

• python version: 3.13.3
• pandas version: 2.3.3
• networkx version: 3.6.1
• scipy version: 1.16.3
• numpy version: 2.3.5
• packaging version: 25.0
• tqdm version: 4.67.3
• deepdiff version: 8.6.2
• Operating System name/version: Ubuntu

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