Simultaneous placement of sub-transmissionsubstations and distributed generation units

since the developing of distributed generation (DG),their penetration into power systems has provided newopportunities in the planning of power system. In this paper, DGunits are considered as an alternative for supplying the load ofsub-transmission system and a new mathematical framework foroptimal sub-transmission substations sitting, sizing and allocationof DG units as well as MV feeders routs are presented. Theproposed method focuses on encouraging DG owners (DGOs) toparticipate in sub-transmission substation expansion planning(SSEP) by considering their benefit through SSEP in planningyears. So, the optimal expansion and operation planning of DGunits, sub-transmission substations, and MV feeders at each loadlevels over planning years are determined through minimizingthe total cost of SSEP and maximizing the benefits of DGOs. Thecost function of developed method consists of investment,construction costs of sub-transmission substations, connectionbetween substations and upper network (HV feeders), new MVfeeders and DG units. Also, the cost of purchased energy fromupper network in forecasted nodal prices cost of energy losses inMV feeders as well as benefits of DGOs are added to objectivefunction. Moreover, prevalent constraints are considered. Theproposed approach is applied to realistic case studies and theresults are compared with several methods.