Power flow calculation for unbalanced three-phase distribution network with DGs based on phase-sequence hybrid modeling

With many distributed generations (DGs) connected to distribution networks, the traditional power flow methods are difficult to deal with PQ(V)-node, PV-node and PI-node types DGs. Therefore, in this paper, a novel power flow algorithm for unbalanced three-phase distribution networks with DGs based on phase-sequence hybrid modeling is proposed. By using the phase-sequence hybrid modeling method, three-phase load models and parameter models of distribution network are established. And combined the special topological structure of distribution network and the three-sequence decoupling-compensation models of unsymmetrical branches with the path-loop circuit analysis method, an effective power flow algorithm for unbalanced three-phase distribution networks is proposed. Then, kinds of DGs are divided into PQ-node, PQ(V)-node, PV-node and PI-node types DGs, their calculation models are derived in detail and can be simply integrated into the proposed power flow algorithm of distribution networks. Test example results show that the proposed method possesses good convergence and efficiency of processing DGs, furthermore, it is verified from the simulation results that robustness and usefulness of the proposed algorithm.