HYGOV Documentation + Implementation

[lukelowry]

Description

Implementation and documentation for the HYGOV PhasorDynamics governor model.

Proposed changes

• Added HYGOV model implementation, documentation, and diagram.
• Added HYGOV JSON parsing and SystemModel assembly support.
• Added focused PhasorDynamicsGovernorHygovTest unit coverage.
• Included source-default curve behavior for zeroed source curve data.
• Updated governor registration, input-format docs, and changelog.

Checklist

• All tests pass (except known PE failure)
• Code compiles cleanly with flags -Wall -Wpedantic -Wconversion -Wextra.
• The new code follows GridKit™ style guidelines.
• There are unit tests for the new code.
• The new code is documented.
• The feature branch is rebased with respect to the target branch.
• I have updated CHANGELOG.md to reflect the changes in this PR.

Further comments

None

[lukelowry]

This model has been rebased and is now up to date and consistant with the other docs and implementations

[nkoukpaizan]

This is close to being ready to merge. A few things to address in addition to the suggested comments:

I'm seeing a couple of test failures on MacOS with GCC. Tests pass with LLVM.

Truncated output:

39: flat-segment plateau gate mismatch: 0.4990295868366958 != 0.4990297247065128
39: --- FAIL: Test turbineDynamics

44: IP mismatch: 0.22000000000000033 != 0.22
44: --- FAIL: Test residualEquations

The following tests FAILED:
	 39 - PhasorDynamicsGovernorHygovTest (Failed)
	 44 - PhasorDynamicsConverterRegcaTest (Failed)

[lukelowry]

Okay, much cleaner now and consistant with the other model. thank you. And I fixed the broken test I believe, I wrote a better test.

[abirchfield]

Thanks Luke. This will be good to get a hydro governor into our cases, as these have different control characteristics than the other ones. The backlash approach seems correct.

[lukelowry]

@nkoukpaizan All ready. All 4 remaining models are rebased and standardized to the best of my . This one is the best of the group