Under the "dual carbon" context

new distribution networks will be developed in the direction of adapting to the high proportion of renewable energy sources（RES）. For meeting the requirements of high reliability and total power supply capacity（TSC）of the new distribution system

the diamond-shaped distribution network（DDN）is proposed in Shanghai based on its own distribution network construction. However

there are limited studies on this network structure. In this paper

the structure of the DDN is introduced firstly and

on this basis

a duplex-diamond-shaped distribution network is proposed. Then

the fault isolation and recovery strategy is generated in accordance with the special structure of the DDN

the reliability assessment algorithm that considers the high proportion of RES is set up and a TSC model of the distribution system with RES on a time-of-day basis is proposed. Finally

the influence of access of large scale renewable energy is analyzed.The reliability and TSC differences among the switch station single-loop network

DDN

and duplex-diamond-shaped distribution network through specific examples is compared through specific calculation example. The superiority of the diamond distribution and the proposed duplex distribution network is verified.