### Technical Report ERGO 11-017

#### Local solutions of optimal power flow

*Waqquas A. Bukhsh, Andreas Grothey, Ken I.M. McKinnon and Paul A. Trodden*

##### Abstract:

The existence of locally optimal solutions to optimal power flow (OPF)
problems has been a question of interest for decades. This paper presents
examples of local optima on very simple power system networks. Usually local
optima occur when the network is stressed, and the resulting voltage profiles
are infeasible in practice; however, we present examples where the voltage is
within practical limits. Standard local optimization techniques are shown to
converge to these local optima if started close enough to them. We also give
examples of local solutions in loop networks. Finally we use a two-bus example
with local optima to illustrate the behaviour of a recent dual semi-definite
programming approach that aims to find the global solution.

##### Download:

ERGO-11-017.pdf

##### History:

Written: November 2011

##### Notes:

A more recent technical report on local solutions of optimal power flow problems is ERGO 13-018