风电系统的非线性模糊恒功率控制器的设计

研究了风速高于额定值时风电系统的非线性模糊恒功率控制。由物理分析得出风电机组的二阶数学模型,采用微分几何的精确反馈线性化理论,对该二阶模型进行全局线性化,得到适用于全局范围的线性模型。应用模糊控制理论对新的系统写出模糊控制规则,进而得到原系统的恒功率控制器。在MATLAB/Simulink中搭建含该非线性模糊变桨距控制器的风力发电机组模型。对阶跃风和随机风分别进行仿真,均能实现风机转速及输出功率的恒定,由此验证了该控制器在额定风速以上的良好控制。     

基于RBFNN的风电机组变桨距反推滑模控制

在风力发电变桨距优化控制问题的研究中,针对具有不确定性的非线性风电机组,设计了基于径向基函数神经网络(RBFNN)的风电机组变桨距反推滑模控制器.首先应用精确反馈线性化理论将原非线性系统模型进行全局线性化处理,再应用RBFNN对不确定项进行逼近,结合滑模控制和反推法,设计反推滑模控制器(BSMC),保证了高风速下风机的稳定性,抑制了不确定项对系统的影响,避免了传统反推法存在的计算复杂问题.通过与传统滑模控制器(SMC)进行仿真对比,结果表明,RBFNN-BSMC能够很好地稳定风电机组的输出功率,具有较强的鲁棒性.     

柴油发电机组非线性H2/H∞综合控制器

独立电力系统的稳定性主要取决于柴油发电机组的转速和电压响应特性.柴油发电机组控制系统是一个非线性控制系统,转速和电压相互作用,对二者进行综合控制非常必要.为了分析系统的动态特性,首先建立柴油发电机组的非线性数学模型,然后以此为基础设计非线性H2/H∞综合控制器.将直接反馈线性化和混合H2/H∞控制理论相结合应用于柴油发...     

基于微分几何的风力发电机组恒功率控制

当风速超过额定值时, 可以通过降低风力机的转速实现恒功率控制从而避免使用复杂的变桨距机构, 本文基于微分几何理论设计了非线性控制器, 实现了变速风力发电机组的恒功率控制. 首先, 分析了风力机的空气动力学特性, 这是所提出的恒功率控制方法的理论依据; 然后, 通过微分几何反馈线性化变换, 将风力机的非线性模型全局线性化; 最后, 基于新的线性化模型设计了非线性控制器, 实现了变速风力机的全局精确线性化控制. 仿真结果表明, 所提出的控制方法在风速大范围变化的情况下能有效的实现变速风力发电机组额定风速以上的恒功率控制.     

非线性不确定中立型系统的鲁棒H∞控制

考虑系统外界干扰、系统参数摄动等非线性扰动环节对中立型时滞系统的H∞影响,提出基于Lyapunov稳定性理论的鲁棒H∞控制器的设计思想.利用线性矩阵不等式(LMI)方法,给出了该类具有状态非线性不确定性中立型时滞系统的鲁棒∞控制器的设计实例.在非线性不确定函数满足增益有界的条件下,得到了该类时滞系统满足鲁棒∞性能的一个充分条件.通过求解一个线性矩阵不等式LMI,即可获得鲁棒∞控制器.仿真结果表明了基于Lyapunov稳定性理论,LMI技术设计的控制器克服了系统外界非线性干扰或系统本身非线性参数摄动的影响,实现了闭环系统的H∞性能条件下的渐近稳定,满足了该系统鲁棒H∞控制的要求.     

DC/DC变换器的动态建模及负载扰动抑制研究

本文针对Buck DC/DC变换器的强非线性和负载变化的特点,建立了近似线性化模型,基于H ∞控制理论设计了扰动抑制鲁棒控制器.给出了求解Buck变换器反馈系统广义被控对象的方法,并利用Matlab鲁棒控制工具箱给出了求解控制器的一般步骤,最后的数字仿真验证了所提方法的有效性和正确性,H∞控制器能大大改善电力电子装置的抗干扰能力.     

低速行驶重型车辆的动力学系统建模与非线性控制

考虑低速行驶工况下的重型车辆，本文建立其纵向行驶驱/制动系统的非线性动力学方程. 在此基础上采用反馈线性化方法将驱/制动工况下的非线性系统转化为线性可控正则型，并针对制动工况下非线性系统存在的控制时滞，提出一种基于非线性SMITH 预估方法的反馈线性化变换，该变换在有效补偿控制时滞同时，实现了制动系统的线性可控正则型转换. 最后，分别基于驱/制动系统的线性可控正则型设计跟踪控制器，实现了车辆低速工况的加/减速度精确跟踪控制.     

一类大时滞非线性网络控制系统的H∞保成本控制

本文研究一类大时滞不确定非线性网络控制系统的H∞保成本控制问题. 首先将具有随机大时滞的网络控制系统模型化为具有不确定系数的离散时间系统模型. 然后利用Lyapunov稳定性理论和线性矩阵不等式方法, 给出H∞保成本控制律的存在条件和H∞保成本控制器的设计方法. 进而通过求解凸优化问题得到最优鲁棒H∞保成本控制器. 最后仿真结果验证了该控制算法的有效性.     

柴油发电机组非线性H2/H∞调速器的研究

船舶电力系统频率的稳定性主要取决于船舶电站柴油机调速系统的转速响应特性. 船舶电站柴油机调速系统是一个非线性控制系统, 为了分析系统的动态特性, 首先建立柴油机调速系统的非线性数学模型, 然后以此为基础设计非线性H2/H∞速器. 将直接反馈线性化和混合H2/H∞控制理论相结合应用于柴油发电机组调速器的设计,把系统的性能要求转化为标准H2/H∞控制问题, 获得了柴油机非线性H2/H∞转速控制律. 计算机仿真结果表明, 设计的非线性H2/H∞调速器有效地提高了系统的动态精度和抑制扰动的能力, 改善了船舶电力系统频率的稳定性.     

基于观测器的非线性系统H_∞模糊可靠控制

研究了基于观测器的非线性系统H∞模糊可靠控制问题.采用T-S模糊模型对非线性系统进行建模,用模糊观测器重构系统状态.在系统发生故障时满足给定H∞性能的约束下.最小化正常情况下的H∞性能,实现次优H∞模糊可靠控制.提出了两种应用线性矩阵不等式(LMI)的H∞模糊可靠控制器设计方法.分别采用两步法和相似变换法将双线性矩阵不等式问题转化为LMI问题.仿真示例验证了所提出方法的有效性.     

具有尾缘襟翼风力机的恒功率反步法控制

尾缘襟翼风力机控制技术在大型风力机领域具有巨大的应用潜力.本文首先基于修正的叶素动量方法建立了具有可变尾缘襟翼的风力机气动模型.针对襟翼风力机的非线性模型,采用反步法设计了非线性控制器,保证系统的控制量和状态变量全局有界,并且风机的输出功率可以收敛到额定功率的一个小邻域内.此外,控制器设计过程中没有将实时风速信息纳入反馈系统,因而降低了工程实施的难度.最后针对12 m/s～15 m/s的阶跃风、基于四分量模型模拟的风载扰动、执行机构受到外部扰动以及总转动惯量具有10%不确定性的工况进行了仿真,仿真结果表明所设计的控制器能有效地稳定风力发电系统的输出功率,控制系统具有较强的鲁棒性.     

变桨距风力发电机组恒功率反馈线性化控制

在额定风速以上时,为保证风电机组的安全稳定运行,需要降低风力机捕获风能,使风力机的转速及功率维持在额定值,基于微分几何反馈线性化方法,提出变桨距风力发电机组恒功率控制策略.建立了风力机的仿射非线性模型,采用微分几何反馈线性化变换实现全局精确线性化;根据新的线性化模型,以风力机转速为输出反馈变量,叶片桨距角为输入控制变量,设计桨距角控制器;在风速高于额定值时调节风力机维持在额定转速,从而实现额定风速以上的恒功率控制.仿真结果表明,所提控制策略能较好地解决变桨距风力发电机组额定风速以上的恒功率控制问题,控制方法具有较好的适应性和鲁棒性.     

Gain-scheduling control of a floating offshore wind turbine above rated wind speed

This paper presents an application of gain-scheduling(GS) control techniques to a floating offshore wind turbine on a barge platform for above rated wind speed cases. Special emphasis is placed on the dynamics variation of the wind turbine system caused by plant nonlinearity with respect to wind speed. The turbine system with the dynamics variation is represented by a linear parameter-varying(LPV) model, which is derived by interpolating linearized models at various operating wind speeds. To achieve control objectives of regulating power capture and minimizing platform motions, both linear quadratic regulator(LQR) GS and LPV GS controller design techniques are explored. The designed controllers are evaluated in simulations with the NREL 5 MW wind turbine model, and compared with the baseline proportional-integral(PI) GS controller and non-GS controllers. The simulation results demonstrate the performance superiority of LQR GS and LPV GS controllers, as well as the performance trade-off between power regulation and platform movement reduction.     

基于滑模控制的含风储多域电力系统负荷频率控制

建立含风储多域互联电力系统负荷频率控制(LFC)模型,同时考虑系统参数不确定性、储能系统和传统机组控制信道延时问题.为提高系统鲁棒性,降低储能系统的容量配置,针对含风储的LFC模型,设计滑模负荷频率控制器,并提出滑模负荷频率控制器和储能协调的控制策略.算例分析表明,所提出的协调控制策略在新能源大规模渗透和系统负荷波动情况下能够有效减小系统频率偏差和区域控制偏差,同时降低储能系统的配置容量,提高电力系统安全稳定运行的经济性.     

Power control of a doubly fed induction generator connected to the power grid

In this paper, the regulation control problem of the active and reactive power at the common connection point between a doubly fed induction generator and the grid is approached. The proposed controller is developed exploiting the passivity properties of the considered model for the control system. It is considered the existence of a wind turbine that delivers a time-varying torque to the generation unit which exhibits a highly nonlinear structure due to the variations of the wind speed. From a theoretical perspective, the main feature of the contribution lies in the fact that it is formally proved that the equilibrium point of the closed-loop system that corresponds to the desired power exhibits practical global asymptotic stability properties. This characteristic is obtained applying well-known theory from the perturbed nonlinear dynamical systems theory. However, in the numerical evaluation of the proposed controller, it is illustrated how these properties are indeed stronger since asymptotic stability is achieved.     

Design of adaptive robust guaranteed cost controller for wind power generator

According to the increasing requirement of the wind energy utilization and the dynamic stability in the variable speed variable pitch wind power generation system, a linear parameter varying (LPV) system model is established and a new adaptive robust guaranteed cost controller (AGCC) is proposed in this paper. First, the uncertain parameters of the system are estimated by using the adaptive method, then the estimated uncertain parameters and robust guaranteed cost control method are used to design a state feedback controller. The controller’s feedback gain is obtained by solving a set of linear matrix inequality (LMI) constraints, such that the controller can meet a quadratic performance evaluation criterion. The simulation results show that we can realize the goal of maximum wind energy capture in low wind speed by the optimal torque control and constant power control in high wind speed by variable pitch control with good dynamic characteristics, robustness and the ability of suppressing disturbance.     

Nonlinear PI control for variable pitch wind turbine

Wind turbine uses a pitch angle controller to reduce the power captured above the rated wind speed and release the mechanical stress of the drive train. This paper investigates a nonlinear PI (N-PI) based pitch angle controller, by designing an extended-order state and perturbation observer to estimate and compensate unknown time-varying nonlinearities and disturbances. The proposed N-PI does not require the accurate model and uses only one set of PI parameters to provide a global optimal performance under wind speed changes. Simulation verification is based on a simplified two-mass wind turbine model and a detailed aero-elastic wind turbine simulator (FAST), respectively. Simulation results show that the N-PI controller can provide better dynamic performances of power regulation, load stress reduction and actuator usage, comparing with the conventional PI and gain-scheduled PI controller, and better robustness against of model uncertainties than feedback linearization control.     

基于反馈线性化的液压型风力发电机组最佳功率追踪控制

液压型风力发电机组在额定风速以下时为获得最多电能,需随风速变化追踪最佳功率点.建立并网液压型风力发电机组仿射非线性数学模型,基于反馈线性化方法,分别以风力机转速和液压系统传输功率为输出,以变量马达摆角为控制输入,线性化系统,设计最佳转速与最佳功率追踪控制器,实现机组在额定风速以下随风速变化输出最佳功率.仿真结果表明,以液压系统传输功率为控制输出的功率追踪过程动静态特性较好.理论分析表明,控制器中高压腔压力变化率是否可以规划,是影响功率追踪过程稳定性的关键因素.     

Comparison between linear and nonlinear control strategies for variable speed wind turbines

The purpose of this work is to compare some linear and nonlinear control strategies, with the aim of benefiting as well as possible of wind energy conversion systems. Below rated wind speed, the main control objective is to perform an optimal wind power capture while avoiding strong loads on the drive train shafts. To explicitly take into consideration the low speed shaft flexibility, a two-mass nonlinear model of the wind turbine is used for controllers synthesis. After adapting a LQG controller based on the linearized model, nonlinear controllers based on a wind speed estimator are developed. They take into account the nonlinear dynamic aspect of the wind turbine and the turbulent nature of the wind. The controllers are validated upon an aeroelastic wind turbine simulator for a realistic wind speed profile. The study shows that nonlinear control strategies bring more performance in the exploitation of wind energy conversion systems.