PICOS/CVXOPT - 'Windows fatal exception: access violation' with MOSEK solver

[SH]

Hello,

I am trying to run an optimal power flow problem with PICOS (which uses CVXOPT) and MOSEK.

However, whenever the MOSEK solver attempts to solve the problem, I get the message ''Windows fatal exception: access violation'' within the log, then the Python kernel restarts.

I have contacted MOSEK staff, and they have identified that the issue is not with the MOSEK solver, but instead due to the line "value = summand + value" found in the PICOS file exp_biaffine.py.

The conclusion was that the crash was caused by adding two objects of types

<class 'cvxopt.base.spmatrix'>   +   <class 'cvxopt.base.matrix'> where the first one is full of zeroes.

Could you inform me as to why this leads to a kernel restart?

Also, I have managed to discover that this issue is isolated to 4 sets of constraints belonging to the optimisation problem.

These constraints have been highlighted in yellow in the attached document containing the code of the optimisation problem.

If these constraints are commented out, then the optimisation problem can be solved.

Furthermore, when the restarting-causing constraints do cause a restart, then that restart issue can persist even when the constraints have been commented out in future attempts to solve the optimisation problem.

The only way that I have discovered so far to deal with this persistent restart issue, is to comment out all but 'k-obj' constraints (highlighted in green in the attached document).

I do not why the restart issue persists despite the restart itself and the commenting out of the troublesome constraints, or why the above solution works.

Thank you.

Regards,

Samuel Hayward

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Please note that the optimisation problem is part of larger Python file, which itself is part of a collection of Python files that work with one another to simulate electrical power systems.

This collection of files is referred to as OPEN (Open Platform for Energy Networks).

It is difficult to send all of the relevant files and folders due to their collective size (even after being compressed), which is why the optimisation problem has been copy-and-pasted into a Word document.

Apologies for any inconvenience this may cause.

If you require any further information about the files or OPEN, then please let me know.

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