Research On Designing Of Variable Speed Constant Frequency Wind Turbine With Speed Regulating Transmission

Wind energy has gained more concerns when the problems of energy deficiency and environment degradation become more serious. Efficiency and reliability are critical issues of the wind turbine. Variable speed wind turbines are very popular on the market since they could capture the maximum amount of energy from the wind if the rotor is operating at an optimal rotor speed. However, the power electronics is very expensive on market that results in overall cost increment. Secondly, the harmonic distortion derived from the process of power converting can play negative effects on the power quality and the grid. Additionally, the high rate of failures is also the main disadvantage of the power electronics. In this paper, we design a type of continuously variable transmission aiming to substitute the expensive and unreliable power electronic components which are widely used on conventional wind turbines.In this paper we first study the fundamental theories about the VACF wind turbine and analyze the technological proposal. We compare the categories, structures and theories of different motors and generators used on the wind turbine. Advanced control methods, such as ZDC, FOC, and DTC, are discussed. Pulse wide method is also studied in this paper, and we conclude the characteristics of different control methods.We present the design of a new type of the drive-train system without the frequency converter for wind turbines. The key of this drivetrain system consists of a planetary gear box and a regulating motor for the speed control. We analyze the kinematics and dynamics of the drivetrain system. We also present the control scheme based on the operating characters of wind turbine. In this scheme, the wind turbine could capture the maximum amount of energy while achieve a constant frequency output of electricity at the same time. We design the control process and algorithm for motor control based on the coordinate transforming theory.The model of each component is built and simulation for the system is conducted using MATLAB/Simulink. A dynamic model of the regulating motor is employed in the torque control to improve the system responding time. Simulation results verify the designed drive-train system for the wind turbine.