Ipopt solves large-scale nonlinear problems

[ccoffrin]

I think you will find this post interesting,

AC Optimal Power Flow in Various Nonlinear Optimization Frameworks

You forgot to add constraints I will look into the Zygote issue. Nonconvex uses l-BFGS Ipopt by default which explains the Hessian.

And this talk,

Benchmarking Nonlinear Optimization with AC Optimal Power Flow | Carleton Coffrin | JuliaCon 2022