Distinction of Magnetization vs. Line Shunt (Validation)

[lukelowry]

Description

Implementation on develop treats the shunt as a magnetizing admittance, which should have a distinct parameter from the line shunt admittance, which does not observe the effects of phase/tap changes. MATPOWER does not seem to make this distinction, but PowerWorld models this correctly. This contributed marginally to errors in magnetization admittances in some cases.

Required before 0.2 release.

Proposed changes

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should be accepted.

Checklist

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• All tests pass.
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
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• There are unit tests for the new code.
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• The feature branch is rebased with respect to the target branch.
• I have updated CHANGELOG.md to reflect the changes in this PR. If this is a minor PR that is part of a larger fix already included in the file, state so.

Further comments

Need to update the circuit mdoel diagram