  This chapter presents recent solutions to the optimal power flow (OPF)
problem in the presence of renewable energy sources (RES), {such} as solar
photo-voltaic and wind generation. After introducing the original formulation
of the problem, arising from the combination of economic dispatch and power
flow, we provide a brief overview of the different solution methods proposed in
the literature to solve it. Then, we explain the main difficulties arising from
the increasing RES penetration, and the ensuing necessity of deriving robust
solutions. Finally, we present the state-of-the-art techniques, with a special
focus on recent methods we developed, based on the application on
randomization-based methodologies.
