Test Case Archive for Global Optimization of OPF Problems

Local Solutions of Optimal Power Flow Problem


The existence of locally optimal solutions to the AC optimal power flow problem (OPF) has been a question of interest for decades. This paper present examples of local optima on a variety of test networks including slightly modified versions of common networks. We show that local optima can occur because the feasible region is disconnected and/or because of nonlinearities in the constraints. Standard local optimization techniques are shown to converge to these local optima. The voltage bounds of all the examples in this paper are between ±5% and ±10% off-nominal. The examples with local optima are available in an online archive [1] and can be used to test local or global optimization techniques for OPF. Finally we use our test examples to illustrate the behaviour of a recent semi-definite programming approach that aims to find the global solution of OPF.






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