This paper presents a wind farm composed of different permanent synchronous generator (PMSG) wind turbines (same wind turbine technology but different rated power or operational conditions) coupled to the same grid connection point. A comparison between the three techniques of wind farm aggregation for a farm composed of PMSG wind turbines. Our comparison is for the closeness of the results of normal and transient response of both the complete model and the aggregated models. The chosen three techniques are, multi full aggregated model using equivalent wind speed (MFAM-EWS), semi aggregated model (SAM) and mixed semi full aggregated model (MSFAM). Simulation has been carried out for these techniques by MATLAB/SIMULINK program to compare them with the complete model to prove the effectiveness of each aggregation technique.