Abstarct: ABSTRACT The presence of single-phase loads and the inequality of number and magnitude of loads in each of the feeder phases of the distribution network cause an imbalance in the lines current and buses voltage. One of the solutions to solve the problem of imbalance is the use of static synchronous compensators (D-Statcoms) in distribution networks, which by injecting reactive power into the buses, that support the voltages and reduce the voltage imbalances. In this thesis, the evaluation of the control performance of D-Statcoms, which are installed multiple times in the unbalanced distribution network, is discussed. In the control method presented in this thesis, the integral to droop line algorithm is used to control the reactive power injection to the buses and the main feature of this algorithm has the minimum fluctuation in reaching the final response. This results in reducing the undesirable interaction between adjacent controllers. The important parameters of this control algorithm are droop coefficients and integral gains. In order to calculate and adjust the droop coefficient and integral gain in this algorithm, it is necessary to create a model for solving the mathematical equations of the optimization problem. In this optimization algorithm, the objective function is defined as a weighted sum of indices such as voltage deviation, voltage unbalance factor and power losses, taking into account the stability condition, which is solved by the Salp Swarm Algorithm. Also, this problem has been solved by three other optimization algorithms such as Genetic Algorithm, Particle Swarm Optimisation and Hybrid Genetic Algorithm and Particle Swarm Optimisation. By applying the obtained optimal gain coefficients to the D-Statcoms, not only the voltage profile is improved, but also the voltage unbalance factor is reduced. The proposed method is simulated on the standard test networks of 5-bus, 10-bus and IEEE 34-bus. In order to evaluate the stability of the system, the eigenvalues analysis has been carried out, and the results show the validity of the presented method in the stability of the system.