Xingjia Yao

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This paper deals with the design of LQG controllers for pitch regulated, variable speed wind turbines where the controller is used primarily for controlling the pitch angle through a collective pitch angle in the high wind speed in order to guarantee the power regulation. The performance of the control is compared to that of a PID controller using the(More)
This paper described a adaptive fuzzy sliding-mode control method applied in the variable speed adjustable-pitch wind turbine, in order to solve the problems of non-linear, parameters time changing, anti-disturbance and time-lag, in which the pitch executor is driven by pitch control unit. The chattering brought by sliding mode switch control can be(More)
Fault diagnosis of a wind turbine gearbox is important to extend the wind turbine system’s reliability and useful life. Vibration signals from a gearbox are usually noisy. As a result, it is difficult to find early symptoms of a potential failure in a gearbox. A novel method based on adaptive Morlet wavelet filter for the crack tooth of wind turbine(More)
With the growing rating of the wind energy generation system, capturing the maximum wind energy and improving the operation efficiency and power quality are becoming more and more important. In Variable Speed Constant Frequency (VSCF) wind energy generation system, the control and design of the grid-side converter is of great importance. This paper(More)
According with control theory of variable-speed and constant-frequency (VSCF) pitch-controlled wind turbine, neural network algorithm is adopted to predict pitch angle at real-time working condition, and to obtain more accurate pitch angle reference value. It enhances control precision of the entire pitch-controlled system.
This paper deals with the design of LQG controllers for pitch regulated, variable speed wind turbines where the controller is used primarily for controlling the pitch angle through a collective pitch angle in the high wind speed in order to guarantee the power regulation. A control sturctrue based on a linear model approach is presented to take into account(More)
—For the variable speed operation of large scale wind turbine, the vibrations become key problem that can not be ignored. In this paper, the active vibration control based on Neural Network PID control strategy was researched. Firstly, PID control algorithm was analyzed. Then, the PID control based on Neural Network was described especially BP Network and(More)
this paper presents a control scheme based on fuzzy logic for adjusting the turbine speed so as to track the maximum power point. The power output from wind turbines varies nonlinearly with the wind speed, the speed of the turbine blade tips and the blade pitch angle. At a given pitch angle and wind velocity, maximum power is obtained at a specific turbine(More)
According to grid codes issued by utilities, tripping of wind turbines following grid faults is not allowed, and it is necessary to provide reactive power support to grid sometime. So this paper sets up a complete DFIG dynamic model, including the generator model, converter model and converter protection, grid model etc. to study the transient characters.(More)
OBJECTIVE To examine the influence of childhood obesity on the early onset of puberty and sex hormones in girls. METHODS Healthy girls with different percentages of body fat at baseline (40 obese, 40 normal, and 40 lean) were recruited from three elementary schools in Shenyang, China. These girls (mean age 8.5 years) were also matched by height, school(More)