MODELING, CONTROL AND SIMULATION OF A PROTOTYPE WIND TURBINE USING S4WT
Mechatronics Engineering, Master’s Thesis, 2012
Prof. Dr. Mustafa Ünel (Thesis Advisor), Assoc. Prof. Dr. Mahmut Akşit, Prof. Dr. Asif Sabanovic, Assoc. Prof. Dr. Kemalettin Erbatur, Assoc. Prof. Dr. Mehmet Yıldız
Date&Time: August 2nd, 2012-14:00
Place: FENS L063
Wind energy is a renewable and sustainable kind of energy that is becoming increasingly important in the last decades. The technologies converting wind energy into usable forms of electricity are developed as alternatives to traditional power plants that rely on fossil fuels. The smallest wind turbines are used for applications such as battery charging or auxiliary power on boats; while large grid-connected wind turbines are designed to generate commercial electricity.
This thesis focuses on modeling, control and simulation of a 500 KW prototype wind turbine that is being developed in the context of the MILRES (National Wind Energy Systems) Project in Turkey. Aerodynamic, mechanical, and electrical models are built in both Samcef for Wind Turbines (S4WT) and Matlab/Simulink environments. S4WT enables to choose each of the turbine components to be used in the composition of prototype wind turbine model, to design their characteristics and the way in which they are connected together and to analyze the behavior of the prototype model. The standard components (tower, bedplate, rotor, rotor shaft, gearbox, generator and coupling shaft) have been used compatible with the IEC 61400-1 in S4WT to perform the simulations. The dynamic equations of aerodynamic, mechanical and electrical models are also modeled in Matlab/Simulink environment.
The main control purpose of the wind turbines is to maximize energy efficiency. However, the turbine must also be protected from excessive loads at different wind speeds. To achieve this goal, generated power curve should be close to the ideal power curve that depicts the optimum energy gathering from the wind depending on the wind speed. The prototype wind turbine is designed to have a nominal power of 500 KW at a nominal wind speed of around 11 m/s. Ideal power curve has two operating regions: Partial load operating region and full load operating region. Partial load operating region has wind speeds lower than the nominal wind speed and full load operating region has wind speeds above the nominal wind speed. The pitch and torque controllers are used to achieve an actual power curve that is very close to the ideal one. A pitch function and a standard PI controller with gain scheduling have been used to control the pitch angle of the blades to limit the power at the full load operating region in S4WT environment. In Matlab/Simulink environment, a simple Proportional (P) controller is used for the pitch controller. The generator torque which consists of an optimal mode gain method is employed in S4WT environment. A sliding mode controller (SMC) is utilized in Matlab/Simulink environment for controlling the torque. Torque controllers which are designed in both environments are used to control the power at both partial and full load operating regions. Kaimal turbulence model has been used to generate realistic wind profiles in TurbSim that can be integrated with S4WT. The performance analysis of 500 KW wind turbine prototype is done for both the partial load and full load operating regions under the power production scenario in S4WT environment. A similar analysis is also carried out in Matlab/Simulink environment using the models and controllers developed in this environment. The prototype turbine is tested under several other scenarios including start up, emergency stop, shut down and parked in S4WT. Simulation results both in S4WT and Matlab are quite successful.