Optimal Expansion Planning of Distribution System and DG Placement Using BPSO

A new method to solve the single and multi-objective distribution expansion planning problems including DG is investigated in this paper. The sizing and placement of DG as well as the required power of the main grid would be optimized using proposed method to meet the demand. Binary Particle Swarm Optimization (BPSO) algorithm is used to solve the optimization problem for three objective functions: total expansion cost, total voltage deviation, and total system loss. The goal of presented model is to satisfy operational and economic requirements by using DG as an alternative candidate for distribution system planning to avoid or at least reduce the expanding existing substations and upgrading existing feeders. The 30-bus distribution system is used in this work to evaluate the proposed algorithm. The conventional Weighted Aggregation Method is used to solve the multi-objective optimization problem so that further objective functions and constraints can be easily added to the proposed algorithm. Optimization results show that the DG has economical and electrical advantages in comparison with the traditional method. NOMENCLATURE MO J Multi-objective function TEC J Objective function of the total expansion cost TVD J Objective function of the total voltage deviation TSL J Objective function of the total system losses EM C Electricity market price ($/ MWh) F Tr j i C , , Fixed cost of the transformer j in the substation i ($/unit) F DG j i C , , Fixed cost of the DG unit j in the load bus i ($/unit) O DG j i C , , Operation cost of the DG unit j in the load bus i ($/MW) DG j i, σ Binary decision variable of the DG unit j in the load bus i Tr j i, σ Binary decision variable of the transformer j in the substation i l σ Binary decision variable of the feeder l DG j i S , Power generated from the DG unit j in the load bus i (MVA) DG i S Total power generated from distributed generation in the load bus i (MVA) MAX DG i S , Distributed generation capacity limit in the load bus i (MVA) Tr i S Total power transferred from electricity market in the substation i (MVA) MAX Tr i S , Maximum substation capacity limit in the substation i (MVA) Tr i P Total active power transferred from electricity market in the substation i (MW)