As a key hub device of AC-DC hybrid distribution system

multi-port power electronic transformer has the functions of bidirectional energy flow

flexible power flow regulation

harmonic and reactive power control and fault isolation

which has attracted more and more attention in recent years. Targeted at the multi-port power electronic transformer oriented for AC/DC hybrid distribution system

this paper deduces the development process of its topological structure. From the perspective of graph theory

the star-type and the series-type structures are catalogued. From the form of the energy pooling part

the common DC-bus structure and high-frequency-coupling structure are summed up. Then

the advantages and disadvantages of different topological structures are compared and analyzed

and the principle of selecting topologies for different practical requirements of AC-DC hybrid distribution system is provided. Furthermore

this paper summarizes the application challenges of multi-port power electronic transformer in simulation

design

control and protection

and its prospects in future technical development are provided.