Cyber-physical framework for emulating distributed control systems in smart grids

•Real-time framework for investigating swarm of controllers in the loop applications.•Extended real-time simulator functionality to allow a large number of connections.•Time delay between the real-time simulator and controller is ∼3–4 ms.•Emulation of the ICT system with NetEm and TC.•Use case: distributed OPF for a 27 nodes dc-network. Algorithm converges in  < 60 s.