Calculation of Three-Phase Unbalanced Power Flow in Distribution Network Containing Distributed Generation

According to actual conditions of three-phase unbalance in distribution network, to accurately calculate the power flow of distribution network connected with various distributed generations (DG) a three-phase unbalanced power flow algorithm based on forward and backward substitutions, that can cope with DG modeled as PV or PQ nodes, is proposed. In accordance with topological structure of distribution network and by use of laterals delaminating technology the calculation of power flow is speeded up. During the coping with DG modeled as a PV node, taking the amplitude of positive sequence voltage as voltage regulating parameter the amplitude difference between positive sequence voltage and rated voltage is calculated, then the amount of reactive power compensation for PV node is obtained and then the DG represented by PV node operation model is changed into that represented by PQ node operation model. The correctness of the proposed algorithm is verified by the calculation results of IEEE 34-bus test system. Finally, by means of analyzing the ability of voltage regulation and reactive power compensation of DG, the impacts of various types of DGs on distribution network voltage are researched.