الفهرس 
الغلافOnly 14 pages are availabe for public view
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Abstract
This thesis introduced modeling, analysis, control and simulation results of a DFIG driven by a wind turbine. Optimum torque control technique is applied to the rotor side converter. The control technique provided satisfactory results for the proposed system and efficiently tracked the available maximum power from wind. In GSC, a grid voltage-oriented vector control method is used to keep the DC bus voltage constant and control the amount of reactive power exchanged with the grid. To regulate stator active and reactive power, RSC has used a stator flux-oriented vector control approach.
A comparison between the performances of a wind turbine driving DFIG using optimal PI controller and AI controllers (FST-PI Controller, FPI-RRO Controller, and SNPI-FST Controller) is presented. The controllers are used for controlling the current loops in the rotor side converter for a DFIG. The rotor direct axis current is set to zero to limit the control of reactive power generation exclusively on the GSC. The system performance using AI controllers has smaller settling time, less fluctuations and more accurate response than conventional PI controller. The best performance of the AI controllers used is for SNPI-FST Controller, then FPI-RRO Controller, and then FST-PI Controller. By using AI controllers, fluctuations in electromagnetic torque can be reduced, thereby reducing vibration and maintenance, and increasing the lifetime of the generator and turbine. AI controllers are robust and simple to design. In addition AI controllers don’t require perfect model knowledge and are used efficiently with linear and nonlinear systems.
During a fault, this thesis provides an ANFIS control approach for a DFIG wind turbine that is connected to the electrical grid. The proposed ANFIS control technology identifies the fault by measuring three-phase voltages and currents at the DFIG wind turbine’s terminals, then activates the crowbar protection system and pitch angle controller during the fault period and deactivates them after the fault has been cleared. The behavior of a DFIG wind turbine during a grid fault is compared with and without the proposed ANFIS. Variations in rotor speed, grid active power, DC-link voltage, and frequency are also evaluated during fault occurrence and after fault clearance. When compared to the scenario without the ANFIS, the simulation findings show that the analyzed grid-connected wind turbines are more stable, have less fluctuation during grid faults, and can return to a stable condition in a short period when fitted with the suggested ANFIS technique. The proposed ANFIS control system has proven its effectiveness in protecting the DFIG in the event of a grid fault.