A New Design of the Objective Function for the Optimal Allocation of Distributed Generation with Short-Circuit Currents

Renewable energy sources reduce irresponsible carbon emissions and have the advantage of being located close to the load as a distributed generation (DG). Thus, various studies have examined the optimal placement and capacity of DG to maximize their effect on power grids. However, there was no paper that considered the normalized cost including the fault current in the process of the optimal allocation of DG. The reason that the normalized fault current cost should be included in objective function is that the more DG is connected to the network, the higher fault current will flow. Thus, this paper presents a method of optimizing the DG placement and capacity from a novel perspective using normalized costs that minimize the fault current. For this purpose, this study incorporates the particle swarm optimization method to the Newton–Raphson power-flow calculation and the sequence network decomposition methods. The proposed normalized cost function includes not only voltage variations determined by the power-flow method, installation costs, and power losses but also fault current determined by the sequence method. As a result, the objective function of the new design, adding the normalized fault current cost, enables the solution set to be more optimal than the previous solution set.