Same local name with reduce_collocation_points

[eslickj]

Summary

I'm using Pyomo DAE's reduce_collocation_points, and I have variables in multiple blocks named "setpoint," leading to a name conflict. I looked into the code and I see where the issue comes form and it seems like a known potential issue. In colloc.py around line 681 (at least in whatever version I have).

        # TODO: Use unique_component_name for this
        list_name = var.local_name + "_interpolation_constraints"

Steps to reproduce the issue

My example is pretty complex, but you just need two blocks with time dependent variables, where the variables have the same local name.

Error Message

RuntimeError: Cannot add component 'setpoint_interpolation_constraints' (type <class 'pyomo.core.base.constraint.ConstraintList'>) to block 'CIB_Chiller_Plant': a component by that name (type <class 'pyomo.core.base.constraint.ConstraintList'>) is already defined.

[eslickj]

Here's my little hack to make it work, in case it's useful.

        # TODO: Use unique_component_name for this
        for ndx in range(1000):
            list_name = f"{var.local_name}_{ndx}_interpolation_constraints"
            try:
                instance.add_component(list_name, ConstraintList())
            except RuntimeError:
                continue

[blnicho]

@eslickj thanks for the bug report. I'll work on getting this fixed.