Optimization of Reactive Power Dispatch Considering DG Units Uncertainty By Dandelion Optimizer Algorithm

Wind energy has become a cornerstone of sustainable electricity generation, yet the reliable integration of wind energy conversion systems (WECSs) into modern grids remains challenged by dynamic variations in wind speed and stringent fault ride-through (FRT) requirements. Among the available technologies, the Doubly Fed Induction Generator (DFIG) and the Permanent Magnet Synchronous Generator (PMSG) dominate commercial applications; however, a comprehensive comparative assessment under diverse grid and fault scenarios is still limited. This study addresses this gap by systematically evaluating the performance of DFIG- and PMSG-based WECSs across three operating stages: (i) normal operation at constant speed, (ii) variable wind speed operation, and (iii) grid fault conditions including single-line-to-ground, line-to-line, and three-phase faults. To enhance fault resilience, a DC-link Braking Chopper is integrated into both systems, ensuring a fair evaluation of transient stability and compliance with low-voltage ride-through (LVRT) requirements. The analysis, performed using MATLAB/Simulink, focuses on active and reactive power, rotor speed, pitch angle, and DC-link voltage dynamics. The results reveal that PMSG exhibits smoother transient responses and lower overshoot compared to DFIG. Under fault conditions, the DC-link Braking Chopper effectively suppresses voltage spikes in both systems, with DFIG achieving faster reactive power recovery in line with grid code requirements, while PMSG ensures more stable rotor dynamics with lower oscillations. The findings highlight the complementary strengths of both technologies and provide useful insights for selecting appropriate WECS configurations to improve grid integration and fault ride-through capability.

This paper presents an improved Direct Power Control (DPC) approach applied to the Grid-Side Converter (GSC) of a wind-driven Permanent Magnet Synchronous Generator (PMSG). The proposed method modifies the conventional switching table by incorporating the errors of the direct and quadrature current components along with the filtered grid voltage vector. The objective is to enhance steady-state behavior and reduce power fluctuations. A comprehensive simulation model is developed in MATLAB/Simulink to assess system performance under different loading conditions and varying wind speeds. Furthermore, the system is evaluated under disturbance conditions, and a comparative validation is performed using classical DPC, Field-Oriented Control (FOC), and Space Vector Pulse Width Modulation (SVPWM)-based FOC. The obtained results confirm that the proposed method achieves improved harmonic and steady-state performance while preserving a relatively simple control structure. Moreover, the Total Harmonic Distortion (THD) of both grid voltage and current remains below 5% at the Point of Common Coupling, complying with IEEE-519 standards. These findings confirm the robustness and effectiveness of the modified DPC scheme in improving power quality and ensuring stable operation of PMSG-based Wind Energy Conversion Systems under variable operating conditions.