Yuning Jiang

Towards Distributed OPF using ALADIN [in press]

This paper discusses the application of the recently proposed augmented Lagrangian alternating direction inexact Newton (<sc>aladin</sc>) method to non-convex ac optimal power flow problems (<sc>ac</sc>-<sc>opf</sc>) in a distributed fashion. In contrast to the often used alternating direction of multipliers method (<sc>admm</sc>), <sc>aladin</sc> guarantees locally quadratic convergence for <sc>ac</sc>-<sc>opf</sc>. Numerical results for 5–300 bus test cases indicate that <sc>aladin</sc> is able to outperform the <sc>admm</sc> and to reduce the number of iterations by about one order of magnitude. We compare <sc>aladin</sc> to numerical results for the <sc>admm</sc> documented in the literature. The improved convergence speed comes at the cost of increasing the communication effort per iteration. Therefore, we propose a variant of <sc>aladin</sc> that uses inexact Hessians to reduce communication. Additionally, we provide a detailed comparison of these <sc>aladin</sc> variants to the <sc>admm</sc> from an algorithmic and communication perspective. Moreover, we prove that <sc>aladin</sc> converges locally at a quadratic rate even for the relevant case of suboptimally solved local nonlinear programs.