ORNL/GridKit

Make PhasorDynamics models Hessenberg-ready

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#463 opened on Jun 24, 2026

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Description

Summary

Track PhasorDynamics models whose state equations are not in explicit derivative form, especially parameter-switched cases where a state can become algebraic.

Rationale

In #439, IEEET1 supports $T_R = 0$ by retagging $V_{ts}$ as algebraic. That works for fully implicit DAE residuals, but can block future Hessenberg-form solvers that need separate differential right-hand-side and algebraic residual methods.

Description

Define a convention for these parametrically piecewise models, then update each affected model so it has a Hessenberg-compatible representation.

Models to cover:

Additional information

Any changes would be mostly mechanical tasks; unclear what the final desired algebraic/differential variant implementation looks like at this time.

We also need to determine:

  • how to document conditionally algebraic states/equations
  • how to reduce the count of duplicate equations if we have multiple variations of each model

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