Research On Dynamic Modeling, Analysis & Fault Diagnosis Of Wind Turbine Gear Transmission System Under Complex Excitations

Gear Transmission system is key component in wind turbine and its running state is directly related to the reliability of the wind turbine. But the nonlinear operation of wind turbine under variable load and condition brings huge challenge in wind turbine condition monitoring and fault diagnosis. According to dynamic model and signal processing, this paper studies the methods of condition monitoring and fault diagnosis in wind turbine.Firstly, this paper analyses the vibration of healthy wind turbine gearbox under complex excitation based on dynamic model. The vibration difference of the same component in each direction and the same direction in each component is compared. The transmission vibration response characteristics in time domain and frequency domain under different levels are also extracted, studying the mathematical relationship between gear fault and vibration signal. Secondly, the paper derives the vibration signal through gear dynamic model, finding that a quarter of the root mean square (RMS) of vibration signal has approximate linear relationship with the gear rotational speed. Then, order analysis is studied on the reliability of wind power gear fault diagnosis according to the gear vibration signal model. Finally, the paper researched the dynamic influence of control delay on wind turbine transmission under MPPT control on the basis of wind turbine pure torsional dynamics model.These studies have found that the nonlinear vibration of wind turbine gear transmission system is mainly affected by multiple excitations. The deeper the degree of gear fault is, the more obvious vibration response and nonlinear characteristics are. The vibration signal can be linearized in time domain by using a quarter of the root mean square (RMS) of vibration signal to decrease the non-linearization influence. Order analysis can effectively extract the low frequency characteristic of wind turbine transmission system, avoiding the frequency aliasing phenomenon and effectively diagnosing the gear fault characteristics. In addition, the control system of wind turbine transmission system has a best time delay value. When the control time delay is closed to the value, the variance of gear meshing force is small and system reliability is high, but when the control time delay is far from the value, the variance of gear meshing force is large and system is unstable.