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AI4OPT / OPFGenerator

Instance generator for OPF problems
MIT License
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Include angle shifts in DC power flow computation #140

Open mtanneau opened 2 weeks ago

mtanneau commented 2 weeks ago

All our DC formulations currently ignore branch angle shifts, which can be non-zero for transformers. We should include these in our Ohm's law equations, and PTDF computation. For Ohm's lawy, it should be straightforward enough. For PTDFs: I don't think it would change the PTDF matrix itself, but it would probably introduce an extra constant term in the RHS. To be investigated.

See reference from powsybl's open load flow: https://powsybl.readthedocs.io/projects/powsybl-open-loadflow/en/stable/loadflow/loadflow.html#dc-flows-computing

mtanneau commented 2 weeks ago

To do this, we would need to extract (and store) branchs' angle shift, which we currently do here where parsing OPFData struct https://github.com/AI4OPT/OPFGenerator/blob/c5093dbc551b7a73f2d87e4daefc7ca7256ffdfc/src/opf/opf.jl#L208

In DC models, Ohm's law would then change from

pf[ij] = -b[ij] * (θi - θj)

to 

pf[ij] = -b[ij] * (θi - θj + φij)

which is the simple update.

I still need to write down the math for the PTDF formulation