Generalized linear two terminal State Space Nodal component models

[MarvinTollnitschRWTH]

This PR generalizes the State Space Nodal (SSN) component model implementation by introducing two new linear two-terminal component types defined by state-space matrices A, B, C, and D:

• SSNTypeV2T – Adds a nodal equation to the MNA system matrix.
• SSNTypeI2T – Adds a mesh equation to the MNA system matrix (analogous to a voltage source).

Additional updates included in this PR:

• Added a variant of the trapezoidal discretization method that omits matrices C and D.
• Implemented an explicit SSN model of a single-phase series RLC circuit to validate the generalized V-type component.
• Enabled pybind support for all three new component models.
• Added test notebooks, a C++ test circuit, and a pybind-based test circuit to verify correctness and integration.

[leonardocarreras]

Hi! Thanks for your PR!

I left some comments mostly on the software. I did not check the equations.

Please consider using pre-commit automatically, so it will format it before you push.

[Copilot]

Pull Request Overview

This PR implements generalized linear two-terminal State Space Nodal (SSN) component models to extend the existing component modeling framework. The implementation provides flexible abstractions for arbitrary linear two-terminal components that can be described using state space matrices A, B, C, and D.

Key changes:

• Introduces two new generalized SSN component types: SSNTypeV2T (voltage-type) and SSNTypeI2T (current-type)
• Adds an explicit Full_Serial_RLC implementation using traditional SSN methods
• Extends the Python bindings to make all three components accessible via pybind

Reviewed Changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
EMT_generalizedSSN_RLC_dpsimpy.ipynb	Test notebook comparing traditional RLC, explicit SSN, and generalized SSN implementations
EMTComponents.cpp	Python bindings for new SSN components with parameter setters and attribute getters
EMT_Ph1_General2TerminalSSN.cpp	C++ test examples demonstrating usage of generalized SSN components
CMakeLists.txt	Build configuration updates to include new test file
MathUtils.cpp/h	New overloaded trapezoidal discretization method for A,B matrices only
SSN component implementations	Three new component classes with their headers and source files
Components.h	Header includes for new SSN components

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[codecov]

Codecov Report

❌ Patch coverage is 81.74037% with 128 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.69%. Comparing base (2ff82a9) to head (ff0965c).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
dpsim-models/src/EMT/EMT_Ph1_SSNTypeI2T.cpp	59.58%	59 Missing ⚠️
dpsim-models/src/EMT/EMT_Ph1_SSNTypeV2T.cpp	56.93%	59 Missing ⚠️
...sim-models/src/EMT/EMT_Ph1_SSN_Full_Serial_RLC.cpp	93.63%	7 Missing ⚠️
dpsim/src/pybind/EMTComponents.cpp	95.58%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #406      +/-   ##
==========================================
+ Coverage   65.22%   65.69%   +0.47%     
==========================================
  Files         374      381       +7     
  Lines       22723    23418     +695     
  Branches    11239    11695     +456     
==========================================
+ Hits        14820    15385     +565     
- Misses       7889     7993     +104     
- Partials       14       40      +26     

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[leonardocarreras]

Hi @MarvinTollnitschRWTH @georgii-tishenin, if you want, you can rebase and confirm that this will be good to merge

[georgii-tishenin]

Hi @MarvinTollnitschRWTH,
thanks for addressing the comments.
I rebased the PR, resolved the addressed and not critical comments. All checks now go through as well. There are still a few active comments left, the main topics are:

• use SPDX header in cpp files as well.
• do not flush in functions that are not part of component's initialization.
• make sure there are no outputs in .ipynb files in git history (strangely, the difference shows it for one of the commits).

Please address the active comments or reply to them if you do not agree. Then, we can merge.

[leonardocarreras]

@leonardocarreras , @MarvinTollnitschRWTH
in the final commit the outputs are clear. But git history for one of the intermediate commits seems to have the output for EMT_generalizedSSN_RLC_dpsimpy.ipynb (at least it's shown in the difference).

How would you proceed? I see two options:

1. Squash commits when merging.
2. git reset to commit before addition of notebooks, commit again and force push

@georgii-tishenin both options work, i think git reset --soft HEAD~6 and adding the files again in the final desired condition is probably the easiest