With the large-scale access of variable distributed energy resources (DERs)

the distribution system will gradually transform from a traditional power network that simply accepts and distributes electric energy to an energy exchange network. In recent years

the construction of smart distribution grids in China is accelerating. Before carrying out other aspects of the modernization of distribution grids

In distribution grid modernization

we should prioritize the grid architecture design

that is

the top-level model design of the distribution grids. Although the total distribution system operator (DSO) model is regarded as the most desirable solution

it has received limited attention in practice. For this reason

this paper investigates the problem under the scientifically established layered and clustered grid architecture. This paper reveals the scientific validity and significance of the total DSO mode and points out the disadvantages of the virtual power plant model with partial DER integration across different local distribution grids. Then this paper further explains several strategic issues related to the implementation of the total DSO model

including redefining distribution services

opening up the meter market

stimulating the growth of new-type power demands and DERs

and establishing new grid design philosophy

thereby reducing the substaintial cost of grid modernization.