Hybrid and coordinated soft starting controller for wind generation system runs in the standalone Micro Grid

Low rating and individual characteristics of the Distributed Generators (DGs) make the standalone Micro Grid (MG) weak power system. When the standalone MG contains wind generation system, special care should be taken during the starting process of the wind generation system to avoid the MG instability. This study proposes a new soft starting controller to improve the starting process of the wind generation system. In the proposed controller, both the wind turbine blade pitch angle (mechanical) and the thyristor switches firing angles (electrical) are coordinated, and controlled simultaneously. The coordination aims to minimize and suppress the undesirable effects and consequences of the wind generation system starting on the standalone MG performance. With employing the proposed hybrid and coordinated controller, the wind generator starting current grows very slowly until it reaches its rated value. On the other side, without employing the proposed controller, the wind generator starting current suddenly jumps and exceeds 400% of its rated value. Also, without employing the proposed controller, the MG frequency drops to less than 49.3 Hz. In addition, the voltage at MG buses drops to 0.9 p.u. in absence of the proposed controller compared with 0.95 p.u. if the controller is employed. The novelty on the proposed controller is the coordination between the thyristor valve firing angle (electronic) and the wind turbine blade pitch angle (mechanical) to achieve the desired performance. The overall performance and the power quality of the standalone MG have been highly improved after employing the proposed coordinated hybrid soft starting controller.