Robust fault estimation for uncertain switched linear systems with time-varying delay

The problem of fault estimation is investigated for a class of uncertain switched systems with time-varying delay. A robust observer-based fault estimator is designed such that the augment error system is exponentially stable and the H∞ performance index meets the predefined requirements. Based on the multiple Lyapunov-Krasovskii functions and the average dwell-time method, the delay dependent sufficient conditions on the existence of desired fault estimator are established. However, since these conditions are not linear matrix inequalities(LMIS), they can not be solved by MATLAB. By using a novel method, these conditions are presented in terms of LMIS. Finally, a numerical example is carried out. The designed fault estimator could tract the fault signal timely. Besides, the error between estimation and fault is very small. Therefore, the validity of the obtained results is illustrated.

Analysis of Fault Arc in High-Speed Switch Applied in Hybrid Circuit Breaker

The behavior of fault arc in a high-speed switch （HSS） has been studied theoretically and experimentally. A simplified HSS setup is designed to support this work. A two-dimensional arc model is developed to analyze the characteristics of fault arc based on magnetic-hydrodynamic （MHD） theory. The advantage of such a model is that the thermal transfer coefficient can be determined by depending on the numerical method alone. The influence of net emission coefficients （NEC） radiation model and P1 model on fault arc is analyzed in detail. Results show that NEC model predicts more radiation energy and less pressure rise without the re-absorption effect considered. As a consequence, P1 model is more suitable to calculate the pressure rise caused by fault arc. Finally, the pressure rise during longer arcing time for different arc currents is predicted.

Fault detection of switched linear systems with its application to turntable systems

This paper is concerned with the H∞ fault detection for continuous-time linear switched systems with its application to turntable systems.The solvability condition for a desired filter is established based on the proposed sufficient condition.Based on the double channel scheme of the turntable control system,the turntable system can be modeled as a switched system.Finally,by taking the turntable system as a numerical example,the effectiveness of the proposed theory is well validated.

Analysis and modeling of resistive switching mechanism oriented to fault tolerance of resistive memory based on memristor

With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of data error. Currently, there are more studies focused on fault tolerance of resistive memory. This paper studies the resistive switching mechanism which may have time-varying characteristics. Resistive switching mechanism is analyzed and its respective circuit model is established based on the memristor Spice model.

Study of the Fast-Closing Switch Used for Fault Current Limiters in Power System

This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.

Observer-based adaptive control of uncertain time-delay switched systems with stuck actuator faults

This paper concerns the observer-based adaptive control problem of uncertain time-delay switched systems with stuck actuator faults. Under the case where the original controller cannot stabilize the faulty system, multiple adaptive controllers are designed and a suitable switching logic is incorporated to ensure the closed-loop system stability and state tracking. New delay-independent sufficient conditions for asymptotic stability are obtained in terms of linear matrix inequalities based on piecewise Lyapunov stability theory. On the other hand, adaptive laws for on-line updating of some of the controller parameters are also designed to compensate the effect of stuck failures. Finally, simulation results for reference [1] model show that the design is feasible and efficient.

Optimal fault detection for a class of discrete-time switched linear systems

This paper deals with the problem of optimal fault detection filter （FDF） design for a class of discrete-time switched linear systems under arbitrary switching. By using an observer-based FDF as a residual generator, the design of the FDF is formulated into an optimization problem through maximizing the H_/H∞ or H∞/H∞ performance index. With the aid of an operator optimization method, it is shown that a mode-dependent unified optimal solution can be derived by solving a coupled Riccati equation. A numerical example is given to show the effectiveness of the proposed method.

Research on a Fast-Closing Switch Based Fault Current Limiter with Series Compensation

A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series. The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors, and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.

基于自然容错开关表的五相永磁同步电机直接转矩控制

五相永磁同步电机(permanent-magnetsynchronous motor,PMSM)传统直接转矩控制(direct torque control,DTC)存在相电流畸变严重、共模电压(common-modevoltage,CMV)高、转矩和磁链脉动大等问题,且无法实现相开路故障情况下的无扰运行。为解决上述问题,提出一种基于自然容错开关表的DTC策略。该策略根据PMSM开路故障前后基电压矢量的特点以及三次平面合成电压矢量为零的原则,构建虚拟矢量(virtual vector,VV),设计故障前后同一套自然容错开关表,进而不但抑制了故障导致的转矩脉动,而且在故障前后均能降低三次谐波电流、减小转矩和磁链脉动、抑制CMV。实验结果验证所提策略的可行性。

在役Switch变流器的故障分析及检修技术应用

文章针对风电机组Switch变流器的故障分析检修问题进行研究,从Switch变流器的结构、原理和功能,常见故障及处理方法,进行在役Switch变流器检修测试平台的设计,检修测试平台的应用实践4个方面进行分析。结果表明,搭建Switch变流器检修测试平台,能显著减少风电场备件支出,提高设备利用率,减轻维修技术人员的工作量,具有推广价值。

基于变分模态分解和改进灰狼算法优化深度置信网络的自动转换开关故障识别

自动转换开关(ATSE)是保证系统连续供电的设备,对其进行健康监测和故障诊断对系统的稳定运行具有重要意义。为了实现对ATSE的非侵入式故障识别,该文提出一种基于电流信号变分模态分解(VMD)的特征提取和改进灰狼算法(IGWO)优化深度置信网络(DBN)相结合的故障诊断方法。该方法首先利用样本熵确定VMD分解次数并对故障电流进行分解;其次对分解后得到的本征模态函数进行小波包能量的提取,并利用IGWO对DBN网络结构参数进行优化;最后通过DBN将电流能量特征与ATSE的故障类型建立起映射关系从而完成最终的故障识别。所提IGWO采用了分段调节与非线性递减的衰减因子相结合的策略,以平衡算法全局搜索和局部搜索能力;并采用莱维飞行更新探狼的移动位置,来避免算法陷入早熟收敛。实验结果表明,该算法不仅能显著提高前期对参数寻优的训练速度,后续泛化实验的故障分类准确率也有98.78%的良好表现。

H_-/H_∞ fault detection filter design for interval time-varying delays switched systems

The problem of the robust fault detection filter design for time-varying delays switched systems is considered in the framework of mixed H-/H∞. Firstly, the weighted H∞ performance index is utilized as the robustness performance, and the H- index is used as the sensitivity performance for obtaining the robust fault detection filter. Then a novel multiple Lyapunov-Krasovskii function is proposed for deriving sufficient existence conditions of the robust fault detection filter based on the average dwell time technique. By introducing slack matrix variable, the coupling between the Lyapunov matrix and system matrix is removed, and the conservatism of results is reduced. Based on the robust fault detection filter, residual is generated and evaluated for detecting faults. In addition, the results of this paper are dependent on time delays,and represented in the form of linear matrix inequalities. Finally,the simulation example verifies the effectiveness of the proposed method.

基于对比学习的电液转辙机故障智能诊断方法

道岔转辙机是铁路运行调度的关键设备,由于其外部使用环境恶劣、内部设备结构复杂,使得转辙机在工作过程中容易产生不同的运行故障。针对广泛应用于高速铁路的电液转辙机,提出基于对比学习的电液转辙机故障智能诊断方法:对电液转辙机左右液压缸油压监测信号使用对比学习的思想正则化特征空间;使用实例级权重策略增强模型泛化能力;使用多种数据增强方法提高模型鲁棒性。最后通过电液转辙机的运行故障实验验证本方法的有效性与优越性。

特高压直流输电工程中性母线开关故障处理策略优化

特高压直流输电工程采用双极共用接地极设计,一个极故障闭锁后需通过极隔离操作实现故障极与运行极的隔离。极隔离操作过程中,如果极中性母线开关发生故障无法分开导致极隔离中断,需配置极中性母线开关故障处理策略继续完成极隔离。根据不同直流故障时对应的工况,分析了中性母线开关故障处理策略存在的不足,基于故障特性优化了故障处理策略,最后通过RTDS仿真试验验证了策略优化的有效性。

执行器部分失效的鲁棒模糊容错切换控制

针对一类具有不确定性、外部扰动和执行器部分失效的非线性工业过程,提出一种鲁棒模糊容错切换控制方法。首先,构建新型多自由度T-S模糊状态空间模型,在此基础上,结合执行器部分失效的情况设计控制律。其次,给出基于线性矩阵不等式(LMI)的容错切换条件和系统稳定条件,并通过当前系统状态和稳定性条件求取其子模型的控制律及相应权值。最后,通过对连续搅拌釜式反应器的仿真研究来验证该文方法的有效性。

开关磁阻电机霍尔位置信号的故障诊断方法

开关磁阻电机(SRM)驱动系统的可靠运行,需要位置传感器提供可靠的位置信号。因此针对霍尔位置传感器时常故障影响电机正常工作的问题,研究一种有效的位置信号诊断方法对于提高系统工作可靠性是有重要意义的。本文提出了一种时间阈值与状态预测相结合的故障诊断方法。首先分析了位置传感器故障的类型和发生位置;其次对所提出的基于时间阈值结合状态预测的方法作了理论分析,该方法将3个位置信号组合的实际状态值与预测状态值作实时比对,结合状态值转换时间进行阈值约束从而检测出各种故障并达到快速准确的效果;最后,为了验证所提方法的有效性,以三相12/8结构电机作为研究对象,对该方法进行了实验验证。实验结果证明了该方法在故障检测中的可行性和有效性。另外,该方法无需复杂的计算和额外硬件即可实现,可推广到无刷直流电机(BLDC)等驱动系统使用。

考虑样本多样性的转辙机故障诊断决策模型

为解决现有研究未充分考虑诊断模型在不同转辙机数据样本条件下的适用性,且单一诊断方法难以满足故障诊断精度与决策要求的问题,提出一种考虑样本多样性的故障诊断决策模型.首先,从ZYJ7电液转辙机8种故障模式和正常模式所对应的油压曲线中分别提取时域、频域、时频域特征量,采用基于核函数的主成分分析法对3个域内的特征量分别降维,得到每个域的特征矩阵,进而构成不同类型的数据样本.然后,基于PSO-KNN、SA-PSO-PNN、PSO-SVM算法构建决策模型.当样本是一般数据样本时,决策模型采用3种算法分别做同一域数据分类,并对同一域各算法诊断结果进行三取二表决,分别得到每一域诊断结果;当样本是大数据样本、不均衡数据样本时,决策模型根据不同样本特点采用3种算法中的推荐算法得到每一域诊断结果.最后,利用决策模型对各域诊断结果进行三取二表决得到最终诊断结果 .仿真结果表明:与单一诊断算法相比,决策模型在大数据样本下,平均准确率提升1.01%;在不均衡数据样本条件下,决策模型的平均准确率提升12.82%;在一般数据样本下,决策模型平均准确率提升6.18%.决策模型通过结合多域的多维特征与各算法特点提高了诊断精度,为集成学习在转辙机故障诊断领域应用提供了一种思路.

基于LADRC的柔性多状态开关平滑切换策略

为实现多端口柔性多状态开关(flexible multi-state switches,FMSS)在所连馈线发生故障时的平滑切换,该文提出一种基于线性自抗扰控制(linear active disturbance rejection control,LADRC)的平滑切换策略,使用LADRC代替比例积分(proportional integral,PI)控制器的直流电压外环并设计解耦状态观测器以便控制器参数调节,引入内环电流指令值反馈以减小其在控制模式切换时的变化幅度,实现FMSS控制模式的平滑切换。通过MATLAB/Simulink仿真,验证了馈线故障出现在PQ或UdcQ控制端口的连接处时,采用基于LADRC的平滑切换策略均可显著减小FMSS的直流电压偏移率,使端口有功功率过渡平滑,迅速恢复稳定,更好地实现了多端口FMSS控制模式的平滑切换。

考虑推力损失的运载火箭主动段容错控制

运载火箭上升段易出现推力下降等动力系统故障,传统的控制方法在干扰性较大场合难以满足高精度、高稳定的控制需求。本文进行了运载火箭自适应增广控制与模糊PD控制方法的研究,并分析两者的控制特性;提出一种基于模糊规则的动态切换控制算法,通过计算自适应PD控制与模糊PD控制的输出量加权,得到系统的最优控制方案;将控制力矩重构与动态切换控制算法结合,进行火箭容错控制研究。结果表明,基于模糊规则的动态切换控制算法能有效提高姿态控制品质,相比于其他控制方法,偏航角最大偏差减小20%以上,系统响应时间至少快15%,且控制过程中未出现振荡。