Hi @timueh! Thanks for your question.
As of PowerModels v0.14, PowerModels focuses on building JuMP models (with DC Power Flow being the only dedicated routine that does not require JuMP). So it is not easy to extract the system of equations into Julia functions, such as
f(x). If you would like to quickly inspect the JuMP model you can do this,
using PowerModels; using JuMP; using Ipopt
m = Model()
result = run_ac_opf("case.m", with_optimizer(Ipopt.Optimizer), jump_model=m)
This issue may be of interest, https://github.com/lanl-ansi/PowerModels.jl/issues/590, which seeks to develop a dedicated AC Power Flow solver in PowerModels that would not require JuMP, which could be used to extract the functions you are interested in.
You might find the
calc_branch_flow_ac functions useful, which simply evaluate the power flow equations on the data model.