Optimizing simulation of such system is done by decoupling  the system

Specialized company like OPAL-RT offer Simulink toolbox to do so, but you can easily do it yourself.

Natural propagation delay from distribution lines can be to decouple the different bus which optimize the computation time of the model.

Chapter 6 from Watson, Neville, and Jos Arrillaga. Power systems electromagnetic transients simulation. No. 39. Iet, 2003. gives the equations for decoupling distribute parameter line.

You can see example of decoupled model there:

http://opal-rt.com/sites/default/files/RT-LAB_Electrical.Applications.ver6-0_02Apr09.pdf

Dear Ghasem,

I am not sure for what you want to optimise the IEEE 14 bus network. But, if it's about optimising the loading/generation/reactive power on this network, it might be worthwhile having a look at MatPower (http://www.pserc.cornell.edu//matpower/). It comes with a range of different test cases (to the best of my knowledge including the IEEE 14 bus network) and includes an Optimal Power Flow implementation.

The good thing about this is that it is not limited to linear cost functions and also allows modelling of 'dispatchable loads' (set the upper active power limit of a 'generator' to 0 and the lower limit to something negative and it will interpret this as a dispatchable load.

But it can only consider (to the best of my knowledge) voltage band constraints and line constraints based on active/reactive/apparent power. You cannot directly constraint line currents.

We're currently using our own optimisation scheme based on MatPower in which we generate the capacity constraints based on sampled sensitivities and use an external optimiser. Works fine too.

If that's what you are looking for, I recommend you have a look at MatPower and its OPF. If this doesn't fully suit your needs, let me know and I'll take you through sensitivity based constraint formulation.

best regards,

    Olav