Add feature to switch lines on/off #606

Summary

Add the feature allowing branches that are modeled in the case file to be disconnected.

Rationale

Contingency analysis or a transmission expansion study would require testing different transmission configurations for stability. Without the ability to connect/disconnect lines by parameter settings, one would need to generate a new case file for each configuration, what could be impractical for large studies.

Description

The solution proposed in #391 could be used as a starting point for switching lines off, especially since the necessary supporting infrastructure is now in place.

A possible caveat of this approach is that it might create a singular system model, for example in case of islanding.

Additional information

I would suggest splitting this work in 2 parts (separate pull requests):

• Following implementation from Branch Status for Out-Of-Service Cases #391.
• Adding support for islanding.