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Abstract — The current transition from passive to active electric distribution networks comes with problems and challenges on bi-directional power flow in the network and the uncertainty in the forecast of power generation from grid-connected renewable and distributed energy sources. The power flow management would need to be distributed, flexible, and intelligent in order to cope with these challenges. Considering the optimal power flow (OPF) problem as a minimum cost flow represented with the graph, this paper applies a cost-scaling push-relabel algorithm in order to solve the OPF in a distributed agent environment. The algorithm’s performance is compared with the successive shortest path algorithm developed in our previous work. The simulation is implemented for both meshed and radial networks. The simulation results show the advantages of the cost-scaling push-relabel algorithm over the shortest path algorithm in the radial networks with respect to significantly reduced number of exchanged messages on the agent platform, and thus the reduced time for calculation. This will be of great importance if the method is to be applied to a large system. Index Terms—Smart grid, active distribution network, optimal power flow, multi-agent system, graph theory, cost-scaling, push-relabel. I