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Meng W.,Zhejiang University | Yang Q.,Zhejiang University | Ying Y.,Zhejiang Windey Co. | Sun Y.,Zhejiang Windey Co. | Sun Y.,Zhejiang University
Proceedings of the American Control Conference | Year: 2013

In this paper, a novel nonlinear adaptive torque controller is proposed for variable-speed wind energy conversion systems to track the maximum power curve. Firstly, the controller is designed for the ideal case where known system parameters are assumed. Then, in the presence of uncertain internal system dynamics, the need for the exact knowledge of the system model is waived by using adaptive technologies. Furthermore, the chattering phenomenon in the generator torque which can result in high mechanical stress is avoided by adopting a modified robust term. Compared with existing methods, no accurate measurement of wind speed is required for the controller design. The control goal is achieved in the sense that the tracking error is guaranteed to converge to an arbitrarily small set. It is theoretically proved that all the signals in the closed-loop system are bounded via Lyapunov synthesis. Finally, the effectiveness and the merit of our proposed controller is shown by simulation on a 1.5MW three-blade wind turbine. © 2013 AACC American Automatic Control Council. Source


Yang F.,Zhejiang Windey Co.
2015 IEEE International Conference on Information and Automation, ICIA 2015 - In conjunction with 2015 IEEE International Conference on Automation and Logistics | Year: 2015

In this paper, a state-feedback based stabilization solution for stochastic high-order nonlinear systems with time-varying delays is presented. By adding one power integrator and increasing the system order by one, a state-feedback based control strategy is proposed for robust stabilization of a class of general uncertain nonlinear systems. Globally asymptotical stability is achieved in probability by choosing an appropriate Lyapunov Krasoviskii function. Rigid theoretical analysis is provided to support the result. © 2015 IEEE. Source


Meng W.,Zhejiang University | Yang Q.,Zhejiang University | Ying Y.,Zhejiang Windey Co. | Ying Y.,North China Electrical Power University | And 4 more authors.
IEEE Transactions on Energy Conversion | Year: 2013

This paper deals with the power capture control of variable-speed wind energy conversion systems. The control objective is to optimize the capture of wind energy by tracking the desired power output. Arbitrary steady-state performance is achieved in the sense that the tracking error is guaranteed to converge to any predefined small set. In addition, to maximize the wind energy capture, transient performance is enhanced such that the convergence rate can be larger than an arbitrary value, which further limits the maximum overshoot. First, an adaptive controller is designed for the case where known aerodynamic torque is assumed. Then, by utilizing an online approximator to estimate the uncertain aerodynamics, the need for the exact knowledge of the aerodynamic torque is waived to imitate the practical experience. With the aid of a novel output error transformation technique, both of the proposed controllers are capable of shaping the system performance arbitrarily on transient and steady-state stages. Meanwhile, it is also proved that all the signals in the closed-loop system are bounded via Lyapunov synthesis. Finally, the feasibility of the proposed controllers is demonstrated on an 1.5-MW three-blade wind turbine using the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code developed by the National Renewable Energy Laboratory. © 2012 IEEE. Source


Zhang D.,Zhejiang University | Li W.,Zhejiang University | Ying Y.,Zhejiang Windey Co. | Zhao H.,State Oceanic Administration | And 2 more authors.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2013

This article describes a double action hydraulic power take off for a wave energy converter of inverse pendulum. The power take off converts slow irregular reciprocating wave motions to relatively smooth, fast rotation of an electrical generator. The design of the double action power take off and its control are critical to the magnitude and the continuity of the generated power. The interaction between the power take off behavior and the wave energy converter's hydrodynamic characteristics is complex, therefore a time domain simulation study is presented in which both parts are included. The power take off is modeled using AMESim®, and the hydrodynamic equations are implemented in MATLAB®; simulation is used to predict the behavior of the complete system. The simulation results show that the design of the double action hydraulic power take off for wave energy converter of inverse pendulum is entirely feasibility and its superiority has been verified by the preliminary experiments, especially compared with the existing single action power take off system. © 2013 IMechE. Source


Lin Z.,Zhejiang Sci-Tech University | Wang H.,Zhejiang Sci-Tech University | Shang Z.,Zhejiang Sci-Tech University | Cui B.,Zhejiang Sci-Tech University | And 2 more authors.
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2015

Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle (β). However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient (Cv) when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve. ©Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2015 Source

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