an minlp approach for optimal dg unit's allocation in radial/mesh distribution systems take into account voltage stability index

application of distributed generation (dg) units in distribution networks has increased in recent years. sizing and sitting of dg units are two important factors which should be considered, especially for reduction of power losses in distribution system. this paper presents a new approach for dg placement in distribution systems using the mixed integer nonlinear programming (minlp). this approach determines the optimal number, sitting and sizing of dg units in both radial and meshed distribution networks with the objectives of reducing the power losses, as well as minimizing the investment and operation costs of dg units, and the monetary value of voltage stability index improvement. the performance of the proposed method is compared with the genetic algorithm (ga), particle swarm optimization (pso), combined ga and pso, and combined loss sensitivity factor and simulated annealing (lsfsa). compared with the conventional methods, the proposed scheme can be applied in the meshed distribution networks as well. a 33-bus radial network and civanlar meshed distribution system have been used for simulation studies. the obtained results approve the efficiency of proposed method for sitting and sizing of dg units in distribution networks.