In this paper, the model of the grid side system GSS is studied in two consequent steps. First, the steady state model of the GSS is developed by using phasor theory; studying the relationships between active and reactive powers, voltage, and currents at different operating modes. Second, control of the grid side converter GSC is studied; developing the grid side dynamic model based on space vector theory. In this paper vector control technique that employs a rotatory reference frame (dq) aligned with the grid voltage space vector is adopted. This control strategy made it possible to achieve the two main objectives of the GSC which are: control of the DC bus voltage and assure transmission of power through the converter, with controlled reactive power exchange. Interval Type-2 Fuzzy Logic Controllers (IT2FLCs) are proposed to control the bus voltage of the DC link. The IT2FLCs proposed in this paper were designed to deal with uncertainty that may occur according to changes during system operation. In this paper, design of GSC controller, which is responsible for the terminal voltage control in addition to the DC link voltage regulation, is done. The developed IT2FLC controller is simulated using MATLAB/SIMULINK software for a 1.5 MW typical wind turbine to verify the performance of the controller. |
