In order to adapt to the increase of distributed generator (DG) penetration

it is of great practical significance to study the theoretical system and specific operation methods of distribution network planning to deal with the randomness of DG output. Aiming at the problems of main transformer “N-1” safety criterion based substation capacity planning and capacity-loading ratio

a simplified optimization model of substation capacity probability planning of DG randomness and a capacity enumeration based solution method are proposed with the minimum total cost objective of substation capacity investment and load outage/random DG abandonment being considered

in order to obtain the substation capacity planning conclusion of active distribution networks with certain engineering application universality. Aiming at the current lack of relevant technical guidelines or research results in the actual planning of active distribution networks

the concepts of DG capacity confidence and capacity-load/generation ratios for active distribution networks are clearly defined

and the proposed simplified model and method are used to obtain the typical value query diagrams/tables of random DG confidence and capacity-load/generation ratios with different DG/load types

different load/DG densities

and different DG/load permeability

thus transforming the complex probability planning method into a traditional planning method in form

so that many basic level planners can use them normally.