考虑寄生参数的隔离型双有源桥DC-DC变换器的开关开路故障分析与容错控制策略

双有源桥(DAB)DC-DC变换器开关管的驱动电路故障导致开关开路故障(OCSF),这使得DAB系统拓扑对称性缺失、高频电压和电流发生畸变和直流偏置,进而对系统的可靠性和长期运行稳定性造成不良影响.对此,研究DAB开关管和高频变压器寄生参数对OCSF后系统运行状态的影响,以完善DAB故障分析体系.针对OCSF问题,提出一种基于对称拓扑和对偶原理的故障容错策略,通过闭锁开关使系统运行拓扑恢复对称,并在此基础上提出一种不改变控制器参数、只需改变控制器输出饱和参数的实用控制方法,并在理论上讨论了该方法的可行性.最后,通过实验验证了OCSF模态分析及所提容错控制策略的正确性.     

五相永磁同步电机缺相运行的建模与控制

为提高五相永磁同步电机(PMSM)控制系统的可靠性,减小定子绕组发生开路故障时电机输出转矩的脉动分量,提出了五相PMSM缺相运行时的容错控制策略。从矢量空间解耦的角度,建立了含有3次谐波磁场的五相PMSM缺相运行时的数学模型。根据瞬时功率守恒原理,对故障前后的电磁转矩进行分析,提出了平均转矩保持不变的容错控制策略,通过重新分配各相电流的幅值和相位,实现了控制系统的满负荷运行;为了使电机在缺相故障时仍能提供平滑转矩,提出了脉动转矩保持为零的容错控制策略,实现了控制系统的无扰运行。采用转子磁场定向的方法,通过对旋转坐标系下的交直轴电流和零序电流进行控制,实现了对电机输出转矩的补偿。实验结果表明,所提出的容错控制算法能够有效改善五相PMSM在定子绕组发生开路故障时的运行性能。     

Neural networks-based adaptive finite-time prescribed performance fault-tolerant control of switched nonlinear systems

In this article, the adaptive finite-time fault-tolerant control problem is considered for a class of switched nonlinear systems in nonstrict-feedback form with actuator fault. The problem of finite-time fault-tolerant control is solved by introducing a finite-time performance function. Meanwhile, the completely unknown nonlinear functions exist in the switched system are identified by the neural networks. Based on the common Lyapunov function method with adaptive backstepping technique, the finite-time fault-tolerant controller is designed. The proposed control strategy can guarantee that the tracking error converges to a prescribed zone at a finite-time and all system variables remain semiglobally practical finite-time stable. Numerical examples are offered to verify the feasibility of the theoretical result.     

Integration of multiple model based fault detection and nonlinear model predictive fault‐tolerant control

In this paper, we present a new fault‐tolerant control system for a class of nonlinear systems with input constraints. Because of many important factors that stabilize a nonlinear model predictive controller, it can be used as a powerful controller in the event of fault occurrence. So, the reconfigurable controller is designed based on the quasi‐infinite model predictive control (QIMPC) approach as a fault‐tolerant approach. On the other hand, a fault detection and diagnosis (FDD) system is designed based on the multiple model method. The bank of extended Kalman filters (EKFs) is used to detect the predefined actuator fault and estimate the unknown parameters of a fault. When a fault is detected, the proposed FDD information is used to correct the model of the faulty system recursively and reconfigure the controller. Delay on FDD decision may lead to performance degradation or even instability for some systems. The timely proposed FDD approach will preserve stability. Moreover, a framework is presented to ensure stability when a fault occurs. The effectiveness of this method is demonstrated, in comparison with conventional nonlinear model predictive control, by two practical examples. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于观测器的无人机编队自适应容错控制

针对多无人机编队飞行中的僚机故障问题,设计了一种基于观测器的自适应容错控制方法。首先,基于领导跟随法建立了无人机编队模型及僚机故障的编队模型,并将其划分为位置子系统与偏航角子系统。其次,基于观测器技术对位置子系统中的状态和故障进行观测,并结合观测的状态和故障信息构造状态反馈控制律;然后,基于自适应方法给出偏航角子系统的控制设计方案,并用Lyapunov理论证明系统跟踪误差最终有界收敛。通过仿真,本文算法在发生故障后对系统的完全跟踪时间和稳态误差分别比基于鲁棒故障估计的方法最大降低了76%和70.3%,并且均比传统观测器的方法明显减少较大,证明了本文算法能更好的克服偏差故障带来的不利影响,有效实现四旋翼无人机群的编队飞行。     

Fault diagnosis and fault-tolerant control of uncertain network control systems

In this article, the equivalent control strategy based on Laplace transform is proposed for the problem of stochastic delay in networked control systems. The original system is transformed into an equivalent control system without random delay block by Laplace transform. Then, a new augmented variable and equivalent control system is introduced to construct an augmented system. An adaptive fault diagnosis observer is designed based on the augmented system. The adaptive turning rate of the observer is obtained by solving the corresponding linear matrix inequality. Based on the information of online fault diagnosis and state estimation, a fault-tolerant controller based on PI control strategy is designed to compensate the fault. Finally, a model of the switched reluctance motor system is considered to show the effectiveness of this method.     

Fault-Tolerant Optimal Neurocontrol for a Static Synchronous Series Compensator Connected to a Power Network

This paper proposes a novel fault-tolerant optimal neurocontrol scheme (FTONC) for a static synchronous series compensator (SSSC) connected to a multimachine benchmark power system. The dual heuristic programming technique and radial basis function neural networks are used to design a nonlinear optimal neurocontroller (NONC) for the external control of the SSSC. Compared to the conventional external linear controller, the NONC improves the damping performance of the SSSC. The internal control of the SSSC is achieved by a conventional linear controller. A sensor evaluation and (missing sensor) restoration scheme (SERS) is designed by using the autoassociative neural networks and particle swarm optimization. This SERS provides a set of fault-tolerant measurements to the SSSC controllers, and therefore, guarantees a fault-tolerant control for the SSSC. The proposed FTONC is verified by simulation studies in the PSCAD/EMTDC environment.      

基于灰色动态预测的风力发电系统容错控制策略研究

提出了一种新型的风力发电系统的主动容错控制策略。引入灰色动态预测模型,对传感器故障进行预测。基于风力发电系统模糊模型,设计容错控制器,利用邻近两状态反馈回路补偿失效回路的系统重构方法,重新确定系统反馈控制律。仿真结果表明在额定风速以下,传感器发生故障时系统的功率系数和叶尖速比均能保持在最优值,从而实现额定风速以下的最大风能捕获。     

Fixed-time fault-tolerant control of uncertain MIMO switched interconnected systems subject to state delay,unknown control directions,and quantized nonlinear inputs

This paper investigates design of an adaptive fixed-time fault-tolerant decentralized controller for a class of uncertain multi-input multi-output (MIMO) switched large-scale non-strict interconnected systems under arbitrary switching subject to unknown control directions, quantized nonlinear inputs, actuator failures unknown external disturbances, and unmodeled dynamics. In addition to interconnected terms, time-varying delayed interconnected terms have been considered in the system model which makes it more general than previous works in the literature. The proposed controller can handle switched systems with unknown switching signal and different types of input nonlinearities including, saturation, backlash, and dead-zone. The singularity problem in designing the fixed time controller has been solved. The quantizer and actuators fault parameters are assumed to be unknown. The Razumikhin lemma has been used to deal with the delayed interconnected terms. To cope with the system unknown dynamics, neural networks (NNs) have been applied and by updating the maximum norms of the networks weight vectors the computational load has been reduced. The explosion of complexity occurring in the traditional back-stepping technique has been avoided by applying dynamic surface control (DSC). Finally, by defining an appropriate common Lyapunov function (CLF), fixed-time convergence of system outputs and the closed-loop system stability have been established. The effectiveness of the proposed controller has been shown via simulation study.     

柔性机械臂振动控制中的压电传感器故障诊断

压电传感器常被应用于结构的振动控制中,为了解决压电传感器故障给控制系统的带来的不稳定问题,根据压电柔性臂振动用压电传感片故障的特点,提出运用小波包变换和RBF神经网络的故障诊断方法。首先运用小波包分解和重构原理将传感器输出信号分解到不同频段中,提取每个频段的能量作为状态监测的特征向量,作为RBF网络的输入,然后利用最佳的RBF神经网络进行压电传感器故障分类。实验结果表明该方法具有良好的非以此线性跟踪能力,置信度达到90%,为后续振动容错控制研究奠定良好的基础。     

基于滑模故障观测器的风能转换系统双频环最优容错控制

为提高风能转换系统在复杂恶劣的环境下正常运行的能力,针对未知故障,设计了基于滑模故障观测器的最优客错控制器.根据风速的多时间尺度特性,建立风能转换系统非线性机理模型.考虑传感器故障,建立风能转换系统的变桨距双频环模型.低频环采用PI稳态优化控制方法,高频环利用滑模故障观测器对未知故障和系统状态进行检测,采用最优容错控制...     

基于虚拟电阻的MMC子模块故障容错环流抑制策略

针对模块化多电平变流器(MMC)子模块故障下容错环流抑制问题,分析了子模块故障状态下的环流特性,进而指出了准比例谐振(PR)控制在子模块故障容错环流控制中的通用优势。通过对采用准PR控制方式的子模块故障容错环流控制器进行分析与改进,提出了一种包含虚拟电阻前馈补偿环节的子模块故障容错环流抑制策略,其在保证实现子模块故障下环流抑制的同时可通过引入的虚拟电阻提高整个控制器的响应速度,使得子模块故障时刻的直流电流以及环流的冲击得到快速、有效的限制,优化了整个系统的性能。仿真与实验结果验证了该环流抑制策略的有效性。     

多相无轴承永磁薄片电机故障运行特性分析

为解决多相无轴承永磁薄片电机因某相发生故障无法正常工作的问题,提出了更具通用性的故障容错控制方法.该方法以相应的断路容错控制方法为基础.考虑到故障相对悬浮力与转矩的影响,重构了其它非故障相定子电流.满足了电机在故障状态下稳定运行所需的悬浮力与转矩,实现了该电机短路和断路故障状态的容错控制.同时,介绍了一种基于相电流反馈量的故障检测方法.最后以该电机同时发生断路、短路故障以及两相短路故障为例,通过仿真和实验验证了所提的容错控制策略的正确性.     

Fault ride-through capability improvement in a DFIG-based wind turbine using modified ADRC

In this paper, an overview of several strategies for fault ride-through (FRT) capability improvement of a doubly-fed induction generator (DFIG)-based wind turbine is presented. Uncertainties and parameter variations have adverse effects on the performance of these strategies. It is desirable to use a control method that is robust to such disturbances. Auto disturbance rejection control (ADRC) is one of the most common methods for eliminating the effects of disturbances. To improve the performance of the conventional ADRC, a modified ADRC is introduced that is more robust to disturbances and offers better responses. The non-derivability of the fal function used in the conventional ADRC degrades its efficiency, so the modified ADRC uses alternative functions that are derivable at all points, i.e., the odd trigonometric and hyperbolic functions (arcsinh, arctan, and tanh). To improve the efficiency of the proposed ADRC, fuzzy logic and fractional-order functions are used simultaneously. In fuzzy fractional-order ADRC (FFOADRC), all disturbances are evaluated using a nonlinear fractional-order extended state observer (NFESO). The performance of the suggested structure is investigated in MATLAB/Simulink. The simulation results show that during disturbances such as network voltage sag/swell, using the modified ADRCs leads to smaller fluctuations in stator flux amplitude and DC-link voltage, lower variations in DFIG velocity, and lower total harmonic distortion (THD) of the stator current. This demonstrates the superiority over conventional ADRC and a proportional-integral (PI) controller. Also, by changing the crowbar resistance and using the modified ADRCs, the peak values of the waveforms (torque and currents) can be controlled at the moment of fault occurrence with no significant distortion.     

模块化多电平换流器子模块故障时中性点移位容错控制策略

模块化多电平换流器(MMC)发生子模块故障后,由于桥臂子模块数目的改变,将使故障相的相电压输出能力发生改变,导致三相输出不对称。针对MMC子模块故障下容错控制问题,以保证子模块故障后线电压平衡为控制目标,提出了一种MMC中性点移位控制(NPSC)容错控制策略。其通过修正故障后各相调制波控制中性点在故障相的相电压矢量方向上进行移位,在完成子模块故障容错运行的同时简化了传统中心点偏移控制算法的复杂程度,易于实现。同时,文中分析了NPSC下对MMC系统运行的影响,指出了该种控制方式下桥臂电流工频分量与直流分量的分配特性。最后,通过仿真与实验进行验证,表明了理论分析与该容错控制策略的有效性。     

模块化多电平变换器上、下桥臂不对称运行环流重复控制

模块化多电平变换器(MMC)以其模块化、可扩展和便于冗余容错设计等优势在高压直流输电等大功率场合得到了很多应用。然而,采用大量电力电子元器件使可靠性成为制约MMC发展的主要因素,而通过设置备用子模块进而实现容错运行成为提高其可靠性的主要手段。针对含备用子模块MMC发生子模块故障导致上、下桥臂不对称运行的情况,本文通过理论分析表明,环流中不仅包含了偶次谐波成分,还包含了不对称运行产生的奇次谐波成分。据此,本文采用改进的环流重复控制器,在实现MMC故障后容错运行的同时,还实现了对环流各次谐波成分的有效抑制。所提出的环流重复控制器,不仅适用于上、下桥臂不对称工况,也适用于对称工况。因此,故障前后无需进行控制器的切换,降低了容错控制的复杂度。本文通过搭建单相MMC硬件平台,验证了所提控制策略的有效性。     

Distributed output estimation error observer-based adaptive fault-tolerant consensus tracking control of multi-agent systems

The purpose of this study is to discuss the fully distributed design of output estimation error observer and fault-tolerant consensus tracking control for a class of multi-agent systems with Lipschitz nonlinear dynamics and actuator faults. Firstly, based on the relative output measurements of neighboring agents, the distributed output estimation error observer is developed to adaptively estimate the state and fault information of each agent, and further overcome the difficulties of online updating the adaptive estimations of unknown hyper-parameters. Secondly, to achieve the state consensus tracking goal and compensate for the negative effects of actuator faults, the distributed fault-tolerant consensus tracking control scheme is proposed on the basis of the state estimation and adaptive fault estimation information, and has excellent robustness and consensus tracking control performance. Moreover, sufficient criteria can ensure that consensus tracking error of each agent converges to a small set near the origin. Finally, numerical simulations are provided to show the effectiveness of the proposed fully distributed algorithm.     

多相电驱重构型车载充电系统绕组开路故障诊断与容错控制

电动汽车(EV)用电驱重构型车载充电系统(EDROC)因其突出的商业价值成为国内外学者的研究焦点。文中针对六相EDROC充电模式中单相绕组开路故障条件下的故障诊断与容错控制进行研究。首先,介绍了六相EDROC的电路拓扑与基本工作原理;其次,针对绕组开路故障问题,提出一种简单易行的故障诊断方法,包括故障检测与故障定位两个环节,分别通过判断电流矢量的角度变化率与绕组电流平均极性实现;然后,研究了系统单相开路故障下的容错控制,通过重新分配绕组电流幅值与相位,实现网侧电流平衡与无旋转磁场;最后,搭建了实验平台,实验结果验证了所提故障诊断方法与容错控制的正确性。     

Observer-based single-network incremental adaptive dynamic programming for fault-tolerant control of nonlinear systems with actuator faults

A model-free incremental adaptive fault-tolerant control (FTC) scheme is proposed for a class of nonlinear systems with actuator faults. To deal with actuator faults and guarantee the approximate optimal performance of the nominal nonlinear system without any prior knowledge of system dynamics, a single-network incremental adaptive dynamic programming (SIADP) algorithm based on incremental neural network observer is developed to design an active fault-tolerant control (AFTC) policy. An approximate linear time-varying system is obtained by incremental nonlinear technique, in which the relevant matrix parameters are identified by recursive least square estimation. Then, a SIADP algorithm-based fault-tolerant controller is developed. Based on the redundancy characteristic and function of actuators, a grouping scheme of actuators is introduced. An incremental neural network observer is designed to approximate the actuator faults. The novel SIADP scheme is constructed with a simplified single critic neural network to shorten the learning time and decrease the computational burden in the control process, in which the norm of the weight estimations of critic neural network is updated. Moreover, based on the Lyapunov theorem, the uniformly ultimately bounded stability of the closed-loop incremental system is proved. Finally, simulations are given to verify the effectiveness of the proposed FTC scheme.     

A long-range adaptive controller for time-varying plants with sudden changes

This paper is concerned with fault detection for adaptive control. Experimental results of the long-range adaptive controller MUSMAR coupled with a fault detection mechanism are presented. The experiments were performed on pilot systems in real time. The fault detection mechanism was used to improve the performance of the MUSMAR controller during the occurrence of faults.