A methodology for optimally tune PI controls in voltage source converters (VSC) is presented. The parameters of the proportional and integral level zero and primary control of the VSC are considered by proposing an objective function based on the error estimation, from the desired and the measured outputs. The minimization of the objective function is performed using particle swarm optimization (PSO) technique. The proposed methodology and the test scenarios are implemented in MATLAB-Simulink for a grid-connected microgrid, which includes a renewable source, load, distribution line and disturbances in reference signals and in the microgrid. The results show the advantages of the proposed methodology considering the adequate performance of the proportional integral control of the converter.