Because of the depletion of fossil fuels, as well as economic and environmental concerns, renewable energy resources (RERs) have become widely integrated into the power system. The permanent magnet synchronous generator (PMSG) is regarded as one of the most promising wind energy conversion technologies (WECS). However, if a fault occurs, the PMSG's behavior will be significantly altered. This study describes a new attempt to optimally design proportional-integral (PI) controllers using a novel partial swarm optimization (PSO) approach. All converters of a grid-connected (PMSG) driven by a variable-speed wind turbine use optimal PI controllers. Such WECSs (WECS) include a machine -side converter (MSC) and a grid-side converter (GSC). The proposed PSO-based PI controllers use a vector control technique to optimally control both of these converters. The MSC is employed for determining the maximum power point. generator currents and reactive generated power Furthermore, the GSC is mostly used to regulate the point of common coupling (PCC) voltage, DC -bus voltage, and grid currents. The PSO is used to minimize the fitness function, which has the squared error of the sum of these variables. The range of the proportional and integral gains of the PI controllers is one of the constraints of the optimization problem. MATLAB/SIMULINK software is used to implement all simulation investigated results, including the PSO code. This is a notable and novel contribution of this study, The proposed PSO based PI controllers are validated against a variety of network disturbances, including balanced and unbalanced faults. The grid-linked PMSG's low voltage ride-through ability can be improved even more with the appropriate PSO based PI controllers.