In order to achieve efficiency

security and sustainability of energy utilization

mainly energy sharing over a wide area and connection of large-scale distributed generator (DG) have to be solved in future distribution network (DN). Thus an optimization model of energy lines planning is built on the principles of optimal energy distribution and investment economy first. And a methodology of establishing the double-layer structure of energy lines is also proposed. Then based on a two-dimensional multi-resolution model of DN with the interconnection of DG

an analysis and calculating method of the maximum allowable capacity of DG considering voltage limits

grid losses and thermal constraints is presented. Finally

simulations are performed on a typical system

and the actual capacity of DG integration for DN with the double-layer structure of energy lines is analyzed as well. It is shown that

compared with traditional network structure

energy resources can not only be locally balanced

but also optimally dispatched and shared over a wide area by the double-layer structure of energy lines. Therefore

the maximum allowable capacity of DG can be increased further. This work is supported by National Natural Science Foundation of China (No. 51377148) and State Grid Corporation of China (No. EPRIYDKJ(2014)3317).