This brief considers the problem of fault detection and isolation using the geometric approach for discrete-time systems. The description of unobservable subspace is presented. The residuals are ...generated by the filter via employing the geometric technique so that each residual is influenced by a specific fault and uncoupled from others. Sufficient conditions are established such that the H ∞ norm of the transfer function is less than a pre-given value. In order to reduce computational cost, an event-triggered mechanism is presented to determine whether the current data should be released or not. Finally, numerical demonstration is given to verify the usefulness of the proposed new design technique.
This work investigates the observer-based asynchronous fault detection problem for a class of nonlinear Markov jumping systems. The conic-type nonlinearities hold such a restrictive condition that ...locates in a known hypersphere with an undefined centre. In order to guarantee the observer modes run synchronously with the system modes, we introduce a hidden Markov model to deal with this difficulty. Utilizing H ∞ and H _ performance index, a multi-targets strategy of asynchronous fault detection problem is formulated. Via linear matrix inequality, sufficient conditions for the presence of the asynchronous fault detection observer are derived respectively. Then an asynchronous fault detection algorithm is formulated. Finally, the application of dynamic equivalent circuit of separately excited DC motor with three cases is employed to illustrate that the devised asynchronous fault detection observer is able to detect the faults after the appearances in the absence of any incorrect alarm.
This paper presents a fault detection and isolation (FDI) method for open-circuit faults of power semiconductor devices in a modular multilevel converter (MMC). The proposed FDI method is simple with ...only one sliding-mode observer (SMO) equation and requires no additional transducers. The method is based on an SMO for the circulating current in an MMC. An open-circuit fault of power semiconductor device is detected when the observed circulating current diverges from the measured one. A fault is located by employing an assumption-verification process. To improve the robustness of the proposed FDI method, a new technique based on the observer injection term is introduced to estimate the value of the uncertainties and disturbances; this estimated value can be used to compensate the uncertainties and disturbances. As a result, the proposed FDI scheme can detect and locate an open-circuit fault in a power semiconductor device while ignoring parameter uncertainties, measurement error, and other bounded disturbances. The FDI scheme has been implemented in a field-programmable gate array using fixed-point arithmetic and tested on a single-phase MMC prototype. Experimental results under different load conditions show that an open-circuit faulty power semiconductor device in an MMC can be detected and located in less than 50 ms.
Abstract There are two sets of standards available in the Chinese market that specify the design requirements and operating tests for arc fault detection devices (GB/T 31143) and arcing fault ...detectors (GB 14287.4) respectively. While arcing fault detectors (AFDs) are claimed to have passed GB 14287.4 standard tests, it remains unclear whether these AFDs can pass GB/T 31143 standards and effectively detect arc fault signals. This study experiments to explore the operational performance of AFDs in the Chinese market based on GB/T 31143 standards, revealing that not all AFDs can pass this test and provide adequate protection for people’s lives and property. The main reason for the failure is that the arcing characteristics, such as flat shoulders and reduced amplitude, of the signal are easily masked by other branch circuit loads.
High-speed trains have become one of the most important and advanced branches of intelligent transportation, of which the reliability and safety are still not mature enough for keeping up with other ...aspects. The first objective of this paper is to present a comprehensive review on the fault detection and diagnosis (FDD) techniques for high-speed trains. The second purpose of this work is, motivated by the pros and cons of the FDD methods for high-speed trains, to provide researchers and practitioners with informative guidance. Then, the application of FDD for high-speed trains is presented using data-driven methods which are receiving increasing attention in transportation fields over the past ten years. Finally, the challenges and promising issues are speculated for the future investigation.
This paper proposes an H_/H
fault detection observer method by using generalized output for a class of polytopic linear parameter-varying (LPV) systems. As the main contribution, with the aid of the ...relative degree of output, a new output vector is generated by gathering the original output and its time derivative, and it is feasible to consider H_ actuator fault sensitivity in the entire frequency for the new system. In order to improve actuator and sensor fault sensitivity as well as guarantee robustness against disturbances, simultaneously, an H_/H
fault detection observer is designed for the new LPV polytopic system. Besides, the design conditions of the proposed observer are transformed into an optimization problem by solving a set of linear matrix inequalities (LMIs). Numerical simulations are provided to illustrate the effectiveness of the proposed method.
This paper proposes a fault detection and classification method for medium voltage DC (MVDC) shipboard power systems (SPSs) by integrating wavelet transform (WT) multiresolution analysis (MRA) ...technique with artificial neural networks (ANNs). The MVDC system under consideration for future all-electric ships presents a range of new challenges, in particular the fault detection and classification issues addressed in this paper. The WT-MRA and Parseval's theorem are employed in this paper to extract the features of different faults. The energy variation of the fault signals at different resolution levels are chosen as the feature vectors. As a result of analysis and comparisons, the Daubechies 10 (db10) wavelet and scale 9 are the chosen wavelet function and decomposition level. Then, ANN is adopted to automatically classify the fault types according to the extracted features. Different fault types, such as short circuit faults on both dc bus and ac side, as well as ground fault, are analyzed and tested to verify the effectiveness of the proposed method. These faults are simulated in real time with a digital simulator and the data are then initially analyzed with MATLAB. The case study is a notional MVDC SPS model, and promising classification accuracy can be obtained according to simulation results. Finally, the proposed fault detection algorithm is implemented and tested on a real-time platform, which enables it for future practical use.
The increased penetration of photovoltaic (PV) systems in different applications with critical loads such as in medical applications, industrial control systems, and telecommunications has ...highlighted pressing needs to address reliability and service continuity. Recently, distributed maximum power point tracking architectures, based on dc-dc converters, are being used increasingly in PV systems. Nevertheless, dc-dc converters are one of the important failure sources in a PV system. Since the semiconductor switches are one of the most critical elements in these converters, a fast switch fault detection method (FDM) is a mandatory step to guarantee the service continuity of these systems. This paper proposes a very fast FDM based on the shape of the inductor current associated to fault-tolerant (FT) operation for boost converter used in PV systems. By implementing fault diagnosis and reconfiguration strategies on a single field-programmable gate array target, both types of switch failure (open- and short-circuit faults) can be detected, identified and handled in real time. The FDM uses the signal provided by the current sensor dedicated to the control of the system. Consequently, no additional sensor is required. The proposed FT topology is based on a redundant switch. The results of hardware-in-the-loop and experimental tests, which all confirm the excellent performances of the proposed approach, are presented and discussed. The obtained results show that a switch fault can be detected in less than one switching period, typically around 100 ms in medium power applications, by the proposed FDM.
PDF
