Research On The Vibration Of The Wind Turbine When Yawing

In recent years, as a new energy wind power generation has been developing continuously and rapidly at home and abroad. And the rise of clean energies such as electricity power from wind has become an important sign of the low-carbon economy. Also wind power generation is a comprehensive and sophisticated science, involving a wide range of science subjects and technical fields. However, compared to the earlier development and utilization of wind energy in Europe and the United States and Japan, the technology of wind power generation in China is not mature, and there is a big gap between the two as modern wind power generation in China started late. The gap is mainly as follows:process design, manufacturing capabilities, single capacity, on-site installation, commissioning and maintenance. In addition, excellent people are relatively scarce in China's wind power generation industry.Statistics from the wind farm show that some wind turbines produce abnormal vibration associated with abnormal noises when it is yawing, which will seriously affects the life of the whole unit as well as brings environmental pollution. This issue has puzzled those in this field as the reasons for it weren't been found. After researching the structure and mechanism of the whole wind turbine, this thesis focuses on the tower, a key part of the entire turbine. Then we use the theory of vibration analysis and software simulation to carry on modal analysis, observe the main modes, and calculate the vibration frequency. And then consider coupling it with the cabin when yaw happens.On these basics, inland firstly for yaw vibration we go to three different wind farm sites which locate in Northeast of China to do on-site measure for 8 turbines, collecting three kinds of signals. They are vertical acceleration, circumferential acceleration of platform in the cabin, yaw motor current value when yaw vibration is proceeding. Then they are used to compare with other similar signals acquired when yaw is going on without abnormal vibration. Later analyze the data with the help of special software. By displaying the time-domain waveform and the signal spectral analysis, we get amplitude spectrum curves and power spectrum curves. After carefully observing and analyzing we come to the conclusions that unsteadiness of the resistance torque is a main cause that leads to vibration at the moment of yawing, and that resonance may occur when self-excited frequency of parts is near to natural frequency of tower.All measures that are good for steadily transferring force and motion during Yawing moment can effectively decrease vibration. Check whether there are material defects in the brake disc, whether the transmission is in good condition of lubrication, whether the assembly and manufacturing of the yaw system meet the requirements. Excessive pressure may cause yaw vibration. The actual yaw rate is about 0.4 degree per second which means that actual speed of relative motion of the friction disc and brake pads is about 7 mm per second. If the braking force is too large we may see the phenomenon that the cabin spins fast some time and slow the other moment. This topic originates from engineering practice, so it is with high practical value.