Elements without connectable bus in exported XML IIDM at bus-branch level

[zamarrenolm]

• Do you want to request a feature or report a bug? Bug

• What is the current behavior? There is a problem related to disconnected elements defined in node-breaker models when exported to IIDM XML using BUS_BRANCH topology level. Probably the same problem can be reproduced with models created at bus-breaker level. The resulting .xiidm file contains the element but there is no reference to a bus, and if it is loaded again by PowSyBl, an IIDM validation exception is raised: com.powsybl.iidm.network.impl.ValidationException: Load 'xxxxx': connectable bus is not set. The output is correct if the topology level selected for output is NODE_BREAKER or BUS_BREAKER.

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem Observed with the following substation configuration:

  

  When exported to BUS_BRANCH topology level, the loads are exported to .xiidm without a connectable bus (original identifiers and names are omitted):

<iidm:voltageLevel id="..." name="..." nominalV="20.0" topologyKind="BUS_BREAKER">
    <iidm:busBreakerTopology/>
    <iidm:load id="..." name="..." loadType="UNDEFINED" p0="0.0" q0="0.0" p="0.0" q="0.0"/>
    <iidm:load id="..." name="..." loadType="UNDEFINED" p0="0.0" q0="0.0" p="0.0" q="0.0"/>
    <iidm:load id="..." name="..." loadType="UNDEFINED" p0="0.0" q0="0.0" p="0.0" q="0.0"/>
</iidm:voltageLevel>

• What is the expected behavior? Either the disconnected elements do not appear in the exported .xiidm, or they are assigned a fictitious connectable bus so the network model can be loaded again from the exported topology level.

• Please tell us about your environment:

  • PowSyBl Version: 3.2.0-SNAPSHOT
  • OS Version: *

[miovd]

Having a fictitious connectable bus would be too confusing in my opinion, I would prefer not to export the disconnected elements. What do you think @mathbagu @geofjamg?