Integration of Distributed Generations (DGs) into Distribution System (DS) brings prominent technical advantages. However, the inappropriate placement and sizing of DGs can cause some problems such as increasing power losses and over/under voltage; Hence, optimum sizing and sitting of DGs is critical. Allocating DGs in an effort to fulfill the preferred circumstance of the system is a non-linear multi-objective constrained optimization problem with high dimension and practical constraints. This paper presents the sizing and siting of DGs based on various types of population-based heuristic optimization algorithms in order to improve the voltage profile and reduce the total power losses of the system. The investigation is executed at the IEEE 33 bus test system to validate the effectiveness of the techniques and additionally evaluate them in different aspects such as their convergence process and their best calculated solutions.
