基于PSCAD的双馈风力发电机的控制模式仿真研究

兆瓦级变速恒频风力双馈发电机通过采用定子磁场定向的转子励磁矢量控制策略可以实现跟踪利用最大风能。在分析了风力机的输出功率和发电机转速的关系特性之后,推导了随机风速下实现最大风能跟踪的目标参考值算法,由此得到三种控制模式:转速控制模式、转矩控制模式、功率控制模式,根据三种控制模式的控制性能的分析比较提出了功率控制模式是最优的控制策略。最后利用PSCAD软件建立了双馈风力发电系统的仿真模型,通过在阶跃风速下的仿真比较,结果验证了结论的正确性。     

宽带IP城域网组网技术及技术进展研究

介绍了宽带IP城域网组网技术，包括ATM技术、POS、千兆比以太网，DPT技术，分析和比较了上述技术的优缺点及实现方法，最后指出IP城域网组网技术的进展。     

Task space control of free-floating space robots using constrained adaptive RBF-NTSM

Trajectory tracking control of space robots in task space is of great importance to space missions,which require on-orbit manipulations.This paper focuses on position and attitude tracking control of a free-floating space robot in task space.Since neither the nonlinear terms and parametric uncertainties of the dynamic model,nor the external disturbances are known,an adaptive radial basis function network based nonsingular terminal sliding mode(RBF-NTSM)control method is presented.The proposed algorithm combines the nonlinear sliding manifold with the radial basis function to improve control performance.Moreover,in order to account for actuator physical constraints,a constrained adaptive RBF-NTSM,which employs a RBF network to compensate for the limited input is developed.The adaptive updating laws acquired by Lyapunov approach guarantee the global stability of the control system and suppress chattering problems.Two examples are provided using a six-link free-floating space robot.Simulation results clearly demonstrate that the proposed constrained adaptive RBF-NTSM control method performs high precision task based on incomplete dynamic model of the space robots.In addition,the control errors converge faster and the chattering is eliminated comparing to traditional sliding mode control.     

Dynamic visual servoing of a small scale autonomous helicopter in uncalibrated environments

This paper presents a novel adaptive controller for image-based visual servoing of a small autonomous helicopter to cope with uncalibrated camera parameters and unknown 3D geometry of the feature points.The controller is based on the back-stepping technique,but its design has two new features.First,it incorporates the visual feedback into the last step of the backstepping procedure,while existing backstepping-based methods employ the visual feedback at the early steps.Second,the controller maps the image er...