Component fault diagnosis for nonlinear systems

In the field of fault diagnosis, the state equation of nonlinear system, including the actuator and the component, has been established. When the faults in the system appear, it is difficult to observe the fault isolation between the actuator and the component. In order to diagnose the component fault in the nonlinear systems, a novel strategy is proposed. The nonlinear state equation with only the component system is built on mathematical equations. The nonlinearity of the component equation is expanded and estimated with Taylor series. If the actuator is perfect, the anomaly of the state equations reflects the component fault. The fault feature index is defined to detect the component fault and the initial fault. The numerical examples of the component faults are simulated for multiple-input multiple-output(MIMO)nonlinear systems. The results show that the component faults,as well as the incipient faults, can be detected. Furthermore, the effectiveness of the proposed strategy is verified. This method can also provide a foundation for the component fault reconfiguration control.

Fault diagnosis and isolation of the componentand sensor for aircraft engine

Aircraft engine component and sensor fault detection and isolation approach was proposed,which included fault type detection module and component-sensor simultaneous fault isolation module.The approach can not only distinguish among sensor fault,component fault and component-sensor simultaneous fault,but also isolate and locate sensor fault and the type of engine component fault when the engine component fault and the sensor faults occur simultaneously.The double-threshold mechanism has been proposed,in which the fault diagnostic threshold changed with the sensor type and the engine condition,and it greatly improved the accuracy and robustness of sensor fault diagnosis system.Simulation results show that the approach proposed can diagnose and isolate the sensor and engine component fault with improved accuracy.It effectively improves the fault diagnosis ability of aircraft engine.

Application of metaheuristic algorithms in interval type-2 fractional order fuzzy TID controller for nonlinear level control process under actuator and system component faults

Purpose–The two-tank level control system is one of the real-world’s second-order system(SOS)widely used as the process control in industries.It is normally operated under the Proportional integral and derivative(PID)feedback control loop.The conventional PID controller performance degrades significantly in the existence of modeling uncertainty,faults and process disturbances.To overcome these limitations,the paper suggests an interval type-2 fuzzy logic based Tilt-Integral-Derivative Controller(IT2TID)which is modified structure of PID controller.Design/methodology/approach–In this paper,an optimization IT2TID controller design for the conical,noninteracting level control system is presented.Regarding to modern optimization context,the flower pollination algorithm(FPA),among the most coherent population-based metaheuristic optimization techniques is applied to search for the appropriate IT2FTID’s and IT2FPID’s parameters.The proposed FPA-based IT2FTID/IT2FPID design framework is considered as the constrained optimization problem.System responses obtained by the IT2FTID controller designed by the FPA will be differentiated with those acquired by the IT2FPID controller also designed by the FPA.Findings–As the results,it was found that the IT2FTID can provide the very satisfactory tracking and regulating responses of the conical two-tank noninteracting level control system superior as compared to IT2FPID significantly under the actuator and system component faults.Additionally,statistical Z-test carried out for both the controllers and an effectiveness of the proposed IT2FTID controller is proven as compared to IT2FPID and existing passive fault tolerant controller in recent literature.Originality/value–Application of new metaheuristic algorithm to optimize interval type-2 fractional order TID controller for nonlinear level control system with two type of faults.Also,proposed method will compare with other method and statistical analysis will be presented.

故障诊断系统开放式软件架构

信号接收系统是电子侦察领域的重要设备。其中的故障诊断功能对于设备的高效使用和发挥效能,具有很重要的作用。本文针对信号接收系统的特点,将故障诊断功能分为健康管理和功能自检两部分,采用模块化、组件化的设计思想,通过数字建模的方法,实现了一种开放式软件架构。通过此方法,不仅可以高效的实现故障检测,而且具有通用性,可以快速拓展到不同的信号接收系统。

Sliding mode observer-based fault detection for helicopter system

Fault detection of non-linear systems is of great importance in control systems reliability.Undetected faults could lead to irreparable damage.This paper deals with fault diagnosis of helicopter system in the presence of uncertainties and disturbances.To deal with sensor,actuator and component faults,the observer-based diagnosis scheme which employs sliding mode observer is designed.Faults are modelled as an additive and multiplicative fault which is introduced as an abrupt and intermittent fault into the system.Observer inequality constraints and gain matrices are solved using a Lyapunov-based approach.The results display the effectiveness of the designed observer and the ability to handle faults.

Inverse-time Backup Protection Based on Unified Characteristic Equation for Distribution Networks with High Proportion of Distributed Generations

The setting work of backup protection using steady-state current is tedious,and mismatches occasionally occur due to the increased proportion of distributed generations(DGs)connected to the power grid.Thus,there is a practical need to study a backup protection technology that does not require step-by-step setting and can be adaptively coordinated.This paper proposes an action sequence adaptive to fault positions that uses only positive sequence fault component(PSFC)voltage.Considering the influence of DGs,the unified time dial setting can be obtained by selecting specific points.The protection performance is improved by using the adjacent upstream and downstream protections to meet the coordination time interval in the case of metallic faults at the near-and far-ends of the line.Finally,the expression and implementation scheme for inverse-time backup protection(ITBP)based on the unified characteristic equation is given.Simulation results show that this scheme can adapt to DG penetration scenarios and can realize the adaptive coordination of multi-level relays.

Renewable Microgrid Protection Strategy Coordinating with Current-based Fault Control

The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the system.The traditional protection principles are unsuitable for RMGs due to the flexibility of RMG operation,the complexity of RMG topology,and the variety of fault control strategies of inverter-interfaced distributed generators(IIDGs).The traditional fault component protection principle is affected by the low voltage ride-through(LVRT)control strategy and will fail in some scenarios.In order to make the fault component protection principle available in every scenario,a current-based fault control strategy is proposed.Specific fault characteristics are generated by the grid-feeding IIDGs during the fault so they can be equivalent to the open circuits,and the fault models in additional network can be simplified.By analyzing the fault characteristics,an RMG protection strategy based on the current-based fault control of IIDGs is presented.The fault directions of feeders can be distinguished and the fault feeder can be located accurately in both grid-connected and islanded RMGs.Then,the grid-feeding IIDGs can transit to LVRT mode smoothly.Thus,IIDGs are considered comprehensively in terms of coordinating with fault control and fault characteristic generation.Finally,the experimental results of the hardware platform prove the effectiveness of the proposed current-based fault control strategy,and the simulation results based on PSCAD/EMTDC verify the correctness of the protection strategy.

New development in relay protection for smart grid

This series of papers report on relay protection strategies that satisfy the demands of a strong smart grid.These strategies include ultra-high-speed transient-based fault discrimination,new co-ordination principles of main and back-up protection to suit the diversification of the power network,optimal co-ordination between relay protection and auto-reclosure to enhance robustness of the power network.There are also new development in protection early warning and tripping functions of protection based on wide area information.In this paper the principles,algorithms and techniques of single-ended,transient-based and ultra-high-speed protection for EHV transmission lines,buses,DC transmission lines and faulty line selection for non-solid earthed networks are presented.Tests show that the methods presented can determine fault characteristics with ultra-high-speed(5 ms)and that the new principles of fault discrimination can satisfy the demand of EHV systems within a smart grid.