A decoupled three-phase power flow algorithm for distribution networks containing multi-transformer-branches

Based on the phase transform technique, the phase transformation matrix is established according to the phase shift relations of three-sequence state variables between two sides of transformer. A novel processing method of transformer branches is proposed, which can be efficiently introduced into a decoupled three-phase power flow algorithm for distribution networks containing multi-transformer-branches. The proposed algorithm makes full use of the characteristics of phase transform and decoupled three-sequence. Then based on the sequence path matrix generated by loop analysis, the relationship between node sequence voltage and injection sequence current can be derived, thus the decoupled three-phase power flow calculation can be successfully realized for unbalanced three-phase distribution networks containing multi-transformer-branches. Finally, the simulated results of IEEE 34-bus test system are provided to verify the correctness and effectiveness of the proposed algorithm, which can also show that this algorithm possesses higher computational efficiency, better convergence, and stronger ability to deal with transformer branches. Different connecting types of transformer and the impacts on unbalanced degrees and distributed levels of three-phase voltages are also discussed in detail.