Full Envelope Wind Turbine Control Systems Design

风力涡轮机是一种提供清洁、安全和丰富能源的手段。它对环境的影响有限，运营成本低。另一方面，风力涡轮机的初始资本成本很高。因此，长寿命和可预测的运行模式是可取的。这项建议旨在通过全包络控制提高风力发电机组的运行寿命和可预测性。风力涡轮机在两种状态下运行：一种是中等风速，其目标是获取最大功率；另一种是较高风速，其功率被调节到接近最大功率。在中等风速和较高风速之间的转换中，系统应该高效和安全地在不同的风速之间移动。大多数大型风力涡轮机都是变速、变桨距结构，其中使用了两种驱动方式：发电机定子的磁场激励，作为磨削力控制旋转；叶片螺距，这会影响气动升力、阻力和发电力。为了降低运营成本，尽可能避免叶片的俯仰，因为这涉及需要润滑的机械部件和有限寿命的轴承。因此，在中等风速时，只使用磁场激励，而在功率调节模式下，同时使用叶片俯仰和磁场激励。从一种状态过渡到另一种状态涉及执行器数量的变化，以及控制系统目标和动态特性的变化。在过渡区，涡轮的超速可能会导致超过额定条件的轴承、扭矩以及叶片和塔架结构中的力。现有的风力机反馈控制方法包括线性变参数概念、最优干扰抑制方法和模型预测控制方法。此外，切换系统将允许更灵活地处理不同的目标、执行器的数量和不同的动力学。这里的工作将考虑这些方法的外推，以处理汽轮机的过渡区控制和全包络运行。状态之间的转换会导致速度和扭矩的振荡，还会增加变桨距执行器的磨损。智能地选择控制策略以避免非线性振荡将有利于实际实施。叶片磨损和损坏引起的动态变化、功率曲线数据的不确定性以及涡轮机之间和与环境的复杂相互作用都会导致在估计最大功率提取参数时出现误差。采用本方案中所述的先进反馈控制技术可以提高效率、最大功率提取和延长汽轮机的寿命。

Wind turbines are a means of providing clean, safe and abundant energy. There is limitedenvironmental impact and the operating costs are low. On the other hand, initial capital costs forwind turbines are high. As such, long life and predictable operating patterns are desirable. Thisproposal aims to improve the life and predictability of operation of wind turbines through fullenvelope control. Wind turbines operate in two regimes: moderate wind speeds where the goal is toextract maximum power and higher wind speeds where power is regulated near capacity. In thetransition between moderate and higher wind speeds the system should efficiently and safely movebetween regimes. Most large wind turbines are of a variable speed, variable pitch configurationwhere two actuations are used: field excitation of the generator stator, governing rotation as abraking force; and blade pitch, which affects the aerodynamic lift and drag and generated forces.For lower operating costs, pitching of the blades is avoided as much as possible as this involvesmechanical components requiring lubrication and bearings with finite lifespans. Thus, at moderatewind speeds only field excitation is used, while in power regulation mode, both blade pitching andfield excitation are employed. Transitioning from one regime to the other involves a change in thenumber of actuators, along with changes in control system goals and in dynamic characteristics. Inthe transition region, overspeeding of the turbine can result in exceeding rated conditions forbearings and torques and forces in the blades and tower structure. All of these issues can greatlyreduce the life expectancy and increase maintenance costs.Promising methods for feedback control of wind turbines include linear parameter varying concepts,optimized disturbance rejection methods and model predictive control. Further, switched systemswill allow more flexibility in dealing with varying objectives, number of actuators, and varyingdynamics. Work here will consider the extrapolation of these methods to handle transition regioncontrol and full envelope operation of the turbine. Transition between regimes can induceoscillations in speed and torques and also increase wear on the pitch actuators. Intelligent choices ofcontrol strategy to avoid nonlinear oscillations would be of benefit to practical implementation.Finding peak power is fraught with difficulty. Varying dynamics due to blade wear and damage,uncertain power curve data, and complex interaction between turbines and with the environmentcan cause errors in estimating parameters for maximum power extraction. Employment of advancedfeedback control techniques as described in this proposal can improve the efficiency, maximumpower extraction and improve life of the turbine.