implement getV and getAngle for busbarsection [WIP]

[jonenst]

Signed-off-by: HARPER Jon [email protected]

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• The commit message follows our guidelines
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Does this PR already have an issue describing the problem ? If so, link to this issue using '#XXX' and skip the rest
NO

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Feature

What is the current behavior? (You can also link to an open issue here)
bbs.getV() throws TODO UnsupportedException

What is the new behavior (if this is a feature change)?
bbs.getV() works

Does this PR introduce a breaking change or deprecate an API? If yes, check the following:
NO

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100.0% Coverage
0.0% Duplication

[jonenst]

To investigate further. Immediate problem: usually algorithms (e.g. a loadflow) will use setV and setAngle on the getBusView(), not the getBusBreakerView(). So use getBusBreakerViewer here doesn't work well.

Other problems:

• V and Angle are stored in the calculated buses (once in the busView calculated buses and once in the busBreakerview calculated buses: these are separate attributes of the voltage level). But they are also stored in the configured buses :

  • nodebreakertopology, getBusBreakerView().setV(...) => calculated BusBreakerView bus
  • nodebreakertopology, getBusView().setV(...) => calculated BusView bus
  • busbreakertopology, getBusBreakerView().setV(...) => configured bus
  • busbreakertopology, getBusView().setV(...) => calculated BusView bus
    But nothing keeps any of these in sync.

• in the iidm inmemory implementation, v and angle are set in all the Terminals (which for the same bus will have the same values), but in networkstore we don't have that. What are the implications

[jonenst]

Maybe we can try the following implementation:

• v theta are only ever stored in the busview-bus objects
• for busbreaker topologies, the configured bus doesn't store the v theta. the busview has the mapping configuredbus -> busview-bus, so it can be used to get v/theta for each configuredbus.
• for nodebreaker topologies, the equipment (e.g. terminal node in iidm in memory) doesn't store the v/theta. The busbreaker view has a mapping from equipments to busbreakerview-buses. The bus view has the mapping from these busbreakerviewb-bus to busview-bus.

[sylvlecl]

We encountered the exception while using network-store implementation for visualizing differences between voltage levels.

Without answering the question of "who should carry the voltage information", it seems to me that it would make sense to simply get the voltage value from the bus view. Indeed the voltage on a busbar must be equal to the voltage of the bus it belongs to.