Model Construction and Power Flow Regulation Analysis of Direct AC/AC Auto-Coupling Three-Winding Hybrid Distribution Transformer

With the increasing penetration of distributed generation, the problems of power flow regulation and voltage fluctuation in distribution network have become prominent. To solve the above problems, this paper proposes a direct AC/AC auto-coupling three-winding hybrid distribution transformer (DAT-HDT), and completes the power flow regulation analysis based on the relaxed two port network theory under the construction of its simplified equivalent impedance model. Firstly, an innovative DAT-HDT topology is designed, and its operation principle is presented. Secondly, the relaxed two-port model of DAT-HDT is constructed. Based on Thevenin theorem, the simplified equivalent impedance model of DAT-HDT is established. Then, considering the equivalent circuit of the distribution network with the simplified equivalent impedance model of DAT-HDT, the principle of DAT-HDT optimal power flow is analyzed, and the corresponding control strategy is proposed. Finally, an IEEE 33-node system simulation example is built to verify the correctness and rationality of the theoretical analysis.