Ensuring the radial operation of the distribution network is a problem that must be considered in the operation and control operation of the distribution network

and with the increasing penetration rate of distributed generators in the distribution network

the operation planning and fault recovery scenarios under the radial constraints of the distribution network are becoming more and more complex. This paper summarizes the radial characteristics of traditional and active distribution networks and the modeling methods of radial constraints in the operation of existing distribution networks. Firstly

the sufficient and necessary conditions of radial constraints in the distribution network are summarized. Then

in detail

the "L−1" condition

spanning tree model

virtual network model

and other radial constraint models of distribution network and their improvement methods are introduced. Through the classification of radial application scenarios

the logical relationship between nodes and branches in the existing radial topology is summarized

and the characteristics of radial constraint models in the operation of various distribution networks are compared from the aspects of the number of variables

the number of formulas

and the applicability of various scenarios. Finally

the selection methods of radial constraint models for various scenarios and the characteristics of radial constraint models are summarized

and the challenges and directions of radial constraint modeling in distribution networks in the future are prospected.