Development of gear transmission technology for large wind turbines
The large wind turbine is mainly composed of a wind wheel, a mechanical transmission system, a power generation device and a control system. The mechanical transmission system is an intermediate device that transmits the wind energy absorbed by the wind wheel to the generator mechanically, including the transmission shaft system and the coupling shaft. In order to facilitate the capture of wind energy and to adapt to the performance control of the unit, the unit must also be equipped with yaw drive, pitch drive and auxiliary devices such as damping and braking. Figure 1 shows a typical large wind turbine. The left side of the wind turbine transmits power through the gearbox to the right generator through the main shaft. The equipment in the nacelle is mounted on the base and supported on the tower by yaw bearings. . .
The special environment and operating conditions of large wind turbines impose unusual requirements on the transmission, and a large number of uncertainties,
The external dynamic load and the variable multi-end wind wheel, the abnormal load of the power grid, the strong vibration caused by insufficient rigidity of the engine room, and the load spectrum that can only be estimated and simulated.
And the ultimate load distribution, etc., are all major issues that the transmission must consider.
The main drive gearbox of a large wind turbine is located between the wind turbine and the generator. It is a heavy-duty gear speed-increasing transmission device that works under the action of irregular variable load and instantaneous strong impact load. The gearbox is one of the most important and most vulnerable components in the wind turbine drive shafting.
The gearbox does not have a solid base in the cabin like the ground. The power matching and torsional vibration of the entire drive train are always reflected in a weak link, which is often the gearbox in the unit. Of course, the ideal situation is to let the gearbox complete the task of transmitting torque and increasing speed without accepting other additional loads. In fact, this can not only be achieved, but also due to the variety of wind conditions and complex deformation of the unit can not avoid the role of many additional loads, adding a lot of uncertain factors to the design of the gearbox.
Obviously, it is important to reduce the size and weight of the components in a small cabin space. Therefore, the gearbox design must ensure that the structure is simplified and the lightest weight while meeting the reliability and life expectancy. Easy to maintain requirements. According to the parameters provided by the unit, CAD optimization design, according to the optimal transmission scheme, select stable and reliable structure and materials with good mechanical properties and remain stable under extreme temperature difference, complete lubrication, cooling and monitoring The system is a necessary prerequisite for the design of the gearbox. .
Therefore, the design of the transmission and the selection of components must be selected according to the requirements of the host, according to different conditions of use, after analysis and comparison. The main factors to consider are:
1) host operating conditions and performance parameters, dynamic analysis results;
2) Load distribution and structural form of the transmission system;
3) requirements for the transmission and its connection;
4) Safety and environmental protection requirements;
5) Life expectancy;
6) Economic and benefit analysis;
7) Operating and maintenance conditions. .
The main gearbox of the conventional unit is used to change the speed and torque so that a compact standard generator can be applied to the unit. Gearboxes of different power classes use different transmission forms.
In the 1980s, parallel-shaft spur gears were applied to standard wind turbines of 100 to 500 kW. In the 1990s, the average power of wind turbines increased to 600 to 800 kW. In order to save space and obtain a larger speed ratio, a planetary gear transmission with a cylindrical shape or a combination of planetary and parallel shaft gears was adopted to achieve better results. .
