Optimal placement of phasor measurement systems for enhancing on-line protection and control of large-scale power systems

Microprocessor-based real-time phasor measurements, i.e. measurement of fundamental frequency, positive sequence, complex three phase voltages and currents, for enhancing on-line protection and control of interconnected electric power systems are described. The proposed research demonstrates that real-time monitoring of key system states, in the bulk power transfer problem, can be identified. It also provides the means for determining which states are the key states for that problem, and that phasor measurements can be used to improve the protection and/or control of the system. The procedure is applied to a realistic system, where such a control problem exists in practice, for confirmation of the developed technique.     

基于观测器的非线性网络控制系统容错控制

研究了一类基于观测器的非线性连续网络控制系统容错控制器设计问题.针对传感器采用时间驱动方式,控制器和执行器均采用事件驱动方式的网络控制系统,设计了观测器,建立了基于状态观测器的增广闭环系统模型.利用线性矩阵不等式和自由权矩阵的方法,推导出闭环系统渐近稳定的充分条件,给出了观测器和容错控制器协同设计的方法.实例仿真证明了所用方法的有效性.     

基于平衡学习的CMAC神经网络非线性滑模容错控制

以一改进的信度分配CMAC(cerebellar model articulation controllers)神经网络为在线故障诊断的手段,将变结构滑模摔制技术引入容错控制器设计之中,提出一种动态非线性系统主动容错控制方法.在常规CMAC学习算法中,误差被平均地分配给所有被激活的存储单元,不管各存储单元存储数据(权值)的可信程度.改进的CMAC中,利用激活单元先前学习次数作为可信度,其误差校正值与激活单元先前学习次数的-p次方成比例,从而提高神经网络的在线学习速度和精度;在此基础上利用滑模控制算法进行容错控制律的在线重构,实现动态非线性系统在线故障诊断与容错控制的集成.分析了系统的稳定性,仿真结果表明改进故障学习算法及容错控制的有效性.     

随机多源干扰系统的复合DOBC和容错控制

针对一类带有多源干扰和常值故障的随机系统,研究其抗干扰和故障诊断问题.多源干扰包括由外源系统生成的部分信息已知的干扰和白噪声干扰两类.第1类干扰包含状态和干扰耦合,不仅可以代表一类部分信息已知的干扰,还可以代表一类随机干扰,且耦合增加了系统的复杂性,导致必然等价原则的无效.为了解决这个问题,提出复合极点配置和线性矩阵不等式(LMI)方法相结合的策略.首先,设计随机干扰观测器来估计第1类干扰;其次,设计随机故障诊断观测器来估计系统故障.基于此,结合容错控制和随机控制,提出基于观测器的复合容错控制策略,在满足一定条件下,该策略可以保证复合系统满足依均方渐近有界.最后,通过仿真验证所提出策略的正确性与有效性.     

Fault-tolerant control based on algebraic derivative estimation applied on a magnetically supported plate

A fault-tolerant control method based on algebraic derivative estimation is introduced. It is applied on an electromagnetically supported plate as an example of a nonlinear and an open-loop unstable system. The design of the closed loop control is facilitated assuming that relevant faults are identified sufficiently precisely and fast. This is justified by a novel robust model-based fault identification scheme which relies on algebraic methods for numerical differentiation. Derivative estimation parameters and fault-detection thresholds are chosen systematically based on the properties of the measurements. The experimental results show the practical usefulness of the presented methods.     

Robustness index for adaptive control based on pole-zero placement

A robustness index for adaptive control is proposed. The control algorithm is based on pole-zero placemen!. Parameter estimation via weighted least-squares recursive formulas is presented. By using the index, effects of the modelling error on the performance of the adaptive control system are indicated. If the index is less than one, the system is stable. Proper on-line control is obtained.     

Fault-tolerant control of nonlinear system

The design strategies of fault-tolerant control system (FTCS) are developed, which are categorized into two types: redundant design and fault compensation. In the first type, a certain degree of redundancy is introduced to controller. The resulting closed-loop system is stable not only when all actuators are operational but also only when one actuator experiences fault. In the second type, the online fault-tolerant control (FTC) scheme is developed based on the fuzzy logic system. The closed-loop stability is established based on Lyapunov’s sense. The resulting closed-loop system is stable by using the corrective control law. Compared with the existing results, the fault is accommodated by the fault compensator. The updating control law is so derived that all the parameters of the closed-loop system are bounded. The advantage of redundant design is that it is unnecessary to know the position and magnitude of the fault and is performed without FDI, which reduce the computing time and avoid the false alarms, non-detection and delay due to FDI. The advantage of fault compensation is the dynamics caused by faults that can be accommodated online. Examples of the proposed design indicate that the approaches are effective.     

基于增量式策略强化学习算法的飞行控制系统的容错跟踪控制

针对发生故障的飞行控制系统,在强化学习算法的基础上,提出了一种基于增量式策略的强化学习容错方法.本方法利用传感器获取的系统状态值,根据系统预先设定的奖励函数对当前控制系统状况做出最优的决策并不断更新价值网络,将系统的容错控制过程转换为强化学习Agent的贯序决策过程,并使用一种改进型的增量式策略实现对当前故障的正确补偿策略的逐渐逼近.同时,针对连续控制系统,提出一种状态转移预测网络来得到下一步状态值.最后,通过南京航空航天大学"先进飞行器导航、控制与健康管理"工信部重点实验室的飞行器故障诊断实验平台验证了该方法的有效性.     

基于气动舵面和RCS融合控制的高超声速飞行器再入姿态容错控制

针对高超声速飞行器再入姿态模型,研究气动舵面故障时的再入姿态容错控制.根据高超声速飞行器再入初期的特点,通常需要反作用控制系统(Reaction Control Systems,RCS)协助气动舵面完成姿态控制.采用Backstepping方法获得期望力矩,将气动舵面视为首要执行机构,在气动舵面之间控制分配期望的力矩.如果气动舵面不能达到期望力矩,则开启RCS,由RCS提供气动舵面不能提供的力矩.考虑舵面发生部分失效和卡死故障情况,设计基于控制分配算法的容错控制策略,使得系统在故障情况下仍旧保持稳定并恢复追踪性能.     

基于三菱FX系列PLC控制的板厚测量系统

本系统利用传统的外圆测量仪,通过相对测量法来测量板的厚度,并利用三菱的FX系列可编程逻辑控制器(PLC)来控制测量仪的定位和数据采集.对其中涉及到的测量原理、系统构成、计算机与PLC的通信等问题进行了论述.     

基于干扰特性指标与推力分配的载人潜水器容错控制

载人潜水器在深海复杂恶劣的环境中运行, 容易受到外部环境干扰和推进器故障的困扰, 本文将干扰特性指标与基于推力分配的主动容错控制方法相结合, 提出了一种新的主动容错控制方法. 首先, 建立了载人潜水器系统的数学模型; 其次, 设计非线性干扰观测器估计系统所受的集总干扰, 并设计无推进器故障时的控制器; 然后, 针对推进器故障问题, 引入权重矩阵进行推力分配以保护故障推进器, 并设计了干扰特性指标表示干扰的性质对跟踪误差和推力损失的影响; 在此基础上, 给出了一种基于干扰特性指标与推力分配的新型容错控制方法, 李雅普诺夫方法保证了该控制算法的理论稳定性; 最后, 通过数值仿真, 验证所设计的控制方法的优越性. 其优越性主要体现在: 能够利用可用干扰与补偿有害干扰, 并将可用的干扰能量用于补偿故障推进器的推力缺失.     

Fault-tolerant control strategy for multicylinder hydraulic press machine based on dynamic control allocation and adjustable multiobjective optimization

A hierarchical controller is proposed for achieving high-accuracy control and the dynamic balance with the presence of multiple faults of actuator, the external disturbance, and the model uncertainties in multicylinder hydraulic press machine (MCHPM). The method divides the controller design into three steps: Virtual fault-tolerant control law, control allocation algorithm, and actuator control law, which are progressive. First, to precisely compensate the lumped disturbances including the multiple faults of actuator, the external disturbance, and the model uncertainties, a disturbance observer (DO) is developed. By combining the observer with the sliding mode control (SMC), a virtual fault-tolerant control law is designed. Second, a highly integrated control allocation algorithm for the virtual fault-tolerant control law is proposed to get the desired driving force, taking into account dynamic control allocation (DCA), multiobjective optimization (MOO) and Analytic Hierarchy Process (AHP) simultaneously. Third, taking the driving force obtained from above control allocation algorithm as the desired target, the control law of each cylinder is calculated. The global stability for the whole system is proved by the Lyapunov theory. Lastly, results of simulation and experiment show that the proposed controller can effectively handle different faults and have more superior control performance.     

Fault-tolerant control of a polyethylene reactor

This work focuses on fault-tolerant control of a gas phase polyethylene reactor. Initially, a family of candidate control configurations, characterized by different manipulated inputs, is identified. For each control configuration, a bounded nonlinear feedback controller, that enforces asymptotic closed-loop stability in the presence of constraints, is designed, and the constrained stability region associated with it is explicitly characterized using Lyapunov-based tools. Next, a fault-detection filter is designed to detect the occurrence of a fault in the control actuator by observing the deviation of the process states from the expected closed-loop behavior. A switching policy is then derived, on the basis of the stability regions, to orchestrate the activation/deactivation of the constituent control configurations in a way that guarantees closed-loop stability in the event of control system faults. Closed-loop system simulations demonstrate the effectiveness of the fault-tolerant control strategy.     

Fault-tolerant traction control of electric vehicles

This paper investigates a new traction control approach that requires neither chassis velocity nor information about tire-road conditions. Plant fault subject to the uncertainties of the mathematical model and slightly sensor fault are concerned. For general traction control of vehicles, the variation of model behavior may break down the steering stability if the chassis velocity is not monitored. This paper presents a fault-tolerant approach based on the maximum transmissible torque estimation (MTTE) scheme which has the ability to prevent electric vehicles from skidding. A PI-type disturbance observer is employed to enhance the steering stability of the MTTE approach. This proposed approach does not require both the differentiator and the inversion of the controlled plant. Finally, illustrated examples are given for evaluating the fault-tolerant performance and feasibility of the presented anti-slip strategy.     

基于测量的接纳控制算法研究综述

介绍了计算机网络QoS研究中基本网络模型、服务模型以及在接纳控制研究中常用的流量描述模型.重点综述了在连接接纳控制研究中占重要地位的基于测量的接纳控制算法,详尽描述和分析了各主要算法的思想、数学模型、应用环境及优缺点,并对各主要算法进行了比较,同时介绍了当前接纳控制研究的一些新进展,包括集成服务网络,区分服务网络及ATM QoS的基于测量的接纳控制研究,并对未来接纳控制研究进行了展望.     

Fault-tolerant control algorithm of the manned submarine with multi-thruster based on quantum-behaved particle swarm optimisation

A thruster reconfiguration control approach of manned submarine with 7000?m operation depth based on quantum-behaved particle swarm optimisation (QPSO) is presented in this article. The manned submarine has eight thrusters. When thruster faults happen, the corresponding weight matrix is updated to restrict the usage of the faulty thruster. But the solution with this method may become unfeasible (exceed the rated valve of the thruster) and cannot be directly applied to the thrusters. In order to complete an appropriate control law reconfiguration, a novel control reallocation method based on QPSO is proposed. Not only is the solution obtained by the approach of QPSO limited in the whole feasible space, but also the control error of the fault-tolerant control is very small. Eight dimensions of the particles are used in this article, and each particle represents the components of the control vector, it searches in the range of the restricted factor value to make sure that all the reconfiguration control solutions are feasible. Compared to the weighted pseudo-inverse method, the error of the obtained control vector with the QPSO is very small. Finally, simulation examples of multi-uncertain faults are given to illustrate the advantages of the proposed method.     

Fault-tolerant control of paper machine headboxes

This paper presents a model-based fault detection and fault-tolerant control technique for the pressurized headbox of a paper machine. A bank of Kalman filters is constructed corresponding to all the possible sensor failure modes. The possibility that each failure mode hypothesis is true is calculated using measurement innovation processes. The sensor failures are detected and located based on the calculated possibilities of the hypotheses. The controller and state estimator are automatically reorganized subsequent to the occurrence of failures to ensure the stability and good performance of the closed-loop system. The issues of system hardware redundancy and computational burden as well as implemental complexity are taken into account in the system design. Simulation results have shown satisfactory performance of the headbox control system after applying the presented technique.     

Fault-tolerant control of three-pole active magnetic bearing

Active magnetic bearings have many advantages over conventional bearings due to contactless operation and adjustable force dynamics. However, one of the obstacles associated with these bearings is failure modes, which may result in destructive rotor dynamic behaviour. One of the important failure modes is electric power outage which may be due to failure of power amplifier, coil or electric wiring. In the present work, a fault tolerant controller has been designed for three-pole magnetic bearings to provide unaltered performance in the event of fault occurrence. The controller has been designed by incorporating the nonlinear fuzzy logic control. The present design of fuzzy logic controller is done by reducing the number of rules of its rule base. Simulations have been carried out to test the performance of the controller for different failure conditions. The designed controller is able to stabilize the rotor for large deviations from the origin even in the presence of failure. The controller is found to be robust as it provides satisfactory operation in the presence of uncertainties.