Dispersed generation impact on distribution network expansion planning

The distribution system is the most extensive part of an electric system and represents the main causes for customer energy interruption. Therefore, the optimal expansion planning of such subsystem including the attractive option of integrating the dispersed generation (DG) can lead to significant economic gains in its installation cost and furthermore minimizing the unserved energy. This paper proposes an integrated model for determining the optimal DG capacity investment and operating cost to serve peak demand as well as the payment reduction toward compensating system losses along the planning period. Thereby, the studied expansion alternatives vary from sizing and sitting of DG generating units or expanding of existing substation and adding new distribution feeders to purchase power from the grid to meet the load demand growth. In the proposed optimization model LINGO software packages is adopted to provide accurate planning decisions. For non-linear constraints both successive linear programming (SLP) and generalized reduced gradient (GRG) algorithms are implemented. Integer models are solved using the branch-and-bound techniques. The different studied alternatives are assessed using present worth analysis to estimate the feasibility of introducing DG in solving the distribution network expansion planning.