| In order to change the changing wind energy into a stable electrical energy output, to fit the grid connection, a flexible drive train of the front-end speed adjusting wind turbine is introduced in this paper. A hydraulic mechanical speed control box that take the hydraulic torque converter as the core, is introduced into this wind turbine drive train and installed before the generator, to regulate the spindle speed to be stable. Due to the use of the torque converter, the rigid connection is changed to a flexible connection. So this kind of drive train can reduce the energy fluctuations caused by the change of wind speed effectively. In order to ensure the high efficiency of the whole wind turbine drive train system, the components of the drive train are optimized and matched reasonably. The working principle of the main part of the drive train is analyzed, including wind rotor, gearbox, hydraulic mechanical transmission, hydraulic torque converter and synchronous generator. As critical parameters, rotational speed ratios of three planetary gear trains are selected as the research subject. The mathematical model of the torque converter speed ratio is established based on these three critical variable quantity, and the effect of key parameters on the efficiency of hydraulic mechanical transmission is analyzed. Based on the torque balance and the energy balance, refer to hydraulic mechanical transmission characteristics. The transmission efficiency of the whole drive train is established. In order to ensure the high efficiency of the torque converter, as the constraints, the rotational speed ratio range of the torque converter is restricted. At the same time, the design rotational speed ratio of the torque converter, corresponds to the common low rotational speed of the wind rotor. In this paper, DeWind8.2wind turbine and NY5torque converter are selected to make a test. The fitness function and constraint functions are established respectively based on the drive train transmission efficiency and the torque converter rotational speed ratio range. And the optimization calculation is carried out by using Matlab genetic algorithm toolbox. The results show that, under the rated rotational speed of the wind rotor, the optimized three key parameters will make the transmission efficiency of the drive train reached the highest value. The optimization method and results provide an optimization program for exact match of wind rotor, gearbox, hydraulic mechanical transmission, hydraulic torque converter and synchronous generator, ensure that the drive train work with a high efficiency, give a reference for the selection of the torque converter and hydraulic mechanical transmission, and provide a necessary foundation to the optimization match design of the large power wind turbine drive chain.Based on the new type of wind turbine drive train, analysis of the key parts was carried out, and mathematical models were established. Simulation models of wind speed, wind turbine aerodynamics, hydraulic torque converter and spindle speed were established in Matlab/Simulink. Including the neural network control model, all models were integrated to establish the whole drive train simulation model. Then, the calculation and simulation were carried out. Based on the maximum wind energy capture, considered the structure parameters of the drive train, the guide vane opening of the hydraulic torque converter was controlled by the neural network to adjust the working oil circulation flow. Then, the torque and the speed of the converter were changed to adapt the change of the wind wheel, to make the spindle speed stabilized at the design value.As a raising speed chain, wind turbine drive train has the characteristic of transmission error amplification. The hydraulic machinery makes the structure of the drive chain more complex. In order to study the transmission error of the front-end speed adjusting wind turbine, the working principle and the source of the error is analyzed. The transmission error formulas about the single gear, the gear pair and the drive shaft are deduced. Based on this, transmission error theoretical research of gear box and hydraulic machinery are respectively carried out. To ensure the torque converter working under the high efficient state, the reasonable structure parameter of the drive train is obtained. At the same time, combined with the characteristic of the planetary gear transmission, the calculation formulas of the whole drive train are derived. According to the probability distribution of all kinds of the transmission error, corresponding sampling formulas are established. Then, based on Monte Carlo method, programming and calculation are carried out in MATLAB. The average value and the range of the angle transmission error are obtained with given accuracy and certain confidence level. Research results lay a foundation for the transmission quality control of the wind turbine drive train. |
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