Nowadays, the challenging errand is enhancing the wind energy system (WES) performance to be more competitive and economically viable. One of the best ways to enhance the performance of the doubly-fed induction generator (DFIG)-based-WES is the optimization of the proportional-integral (PI) controllers for the variable frequency converter system. Many objectives with different optimization techniques have been used in literature to achieve optimal performance. Each choice has its advantages and disadvantages. This paper presents a new design approach for better performance of PI controllers and, hence DFIG over a wide range of operating conditions through two main themes. The first is by introducing a new multi-objective formulation, while the second is utilizing recent optimization techniques like Grey Wolf Optimizer and Whale Optimization Algorithm. Four PI controllers are optimized using a traditional objective function and the proposed multi-objective formulation. Two are related to the Rotor Side Converter (RSC), named power regulator, and the main rotor side converter current regulator. The other two PI controllers related to Grid Side Converter (GSC) are the DC-link voltage regulator and the main grid-side converter current regulator. A performance comparison is held through normal and abnormal operating conditions on a simulation model of a 6 MW wind farm located in Jabal Alzayt along the Red Sea Coast in Egypt and directly connected to the grid. The results confirmed the effectiveness of the proposed approach to help the DFIG-based-WES to agree with the Egyptian Grid Code during disturbances compared with the traditional objective formulation.