Fault indicator

About: Fault indicator is a research topic. Over the lifetime, 10057 publications have been published within this topic receiving 143482 citations. The topic is also known as: FCI & power line fault indicator.

Online digital fault locator for overhead transmission line

Abstract: The ability to determine quickly and accurately where faults have occured on a transmission line has long been an operating man's dream. This paper describes a completely digitalised online fault locator which takes input signals from existing c.t.s and p.t.s and works on a reactance-ratio-measurement principle. It operates in less than two cycles from the instant that the relay delivers a trip output, and is therefore capable of locating transient as well as permanent short-circuit faults. Furthermore, a suitable compensation in fault-locator inputs is proposed which results in increased resistive coverage for the suggested fault locator when applied to double-end feed lines.

Fault Detection Isolation and Estimation in a Vehicle Steering System

Abstract: Recently, a bond-graph-based fault detection and isolation (FDI) framework has been developed with a new concept of global analytical redundancy relations (GARRs) (Low, Wang, Arogeti, and Luo, 2009, 2010; Low, Wang, Arogeti, and Zhang, 2010). This new concept allows the fault diagnosis for hybrid systems which consist of both continuous dynamics and discrete modes. A failure of a safety critical system such as the steering system of an automated guided vehicle may cause severe damage. Such failure can be avoided by an early detection and estimation of faults. In this paper, the newly developed FDI method is studied in details using an electrohydraulic steering system of an electric vehicle. The steering system and faults are modeled as a hybrid dynamic system by the hybrid bond graph (HBG) modeling technique. GARRs are then derived systematically from the HBG model with a specific causality assignment. Fault detection, isolation, and estimation are applied, experimental setup is described, and results are discussed.

Method and system for diagnostics of apparatus

Abstract: Proposed is a method, implemented in software, for estimating fault state of an apparatus outfitted with sensors. At each execution period the method processes sensor data from the apparatus to obtain a set of parity parameters, which are further used for estimating fault state. The estimation method formulates a convex optimization problem for each fault hypothesis and employs a convex solver to compute fault parameter estimates and fault likelihoods for each fault hypothesis. The highest likelihoods and corresponding parameter estimates are transmitted to a display device or an automated decision and control system. The obtained accurate estimate of fault state can be used to improve safety, performance, or maintenance processes for the apparatus.

Fault Detection and Isolation in Medium-Voltage DC Microgrids: Coordination Between Supply Power Converters and Bus Contactors

Abstract: A fast and effective method for detecting and isolating faults in medium-voltage dc microgrids relies on rapid coordination between power supply converters and bus segmentizing contactors to limit currents and isolate faults without any need for fast communication between these active elements. The power converters independently enter current-limiting mode as soon as they recognize a fault condition and the segmentizing contactors autonomously decide whether or not to open based on their local interpretation of time-to-trip curves as functions of apparent circuit resistance. This method allows converters and contactors to use only local measurements when discerning whether or not to trip in order to isolate the faulted section. Simulation and experimental results show that low-impedance short-circuit faults can be isolated within 10–20 ms and the system can be reenergized within 40–60 ms. The method is effective for a wide range of fault and system configurations, and that range can likely be expanded by applying additional discrimination methods.

Simultaneous Placement of Fault Indicator and Sectionalizing Switch in Distribution Networks

Abstract: Automation systems provide substantial improvement in service reliability through speeding up fault management procedure. However, this is at expense of high investments whose justification needs thorough cost/worth analyses. This paper introduces a mathematical model to optimally place automation system devices within distribution networks. The model establishes a trade-off between service reliability improvements and the relevant costs. Among different automation system devices, fault indicators and remote controlled switches are considered here. Also, the impact of manual switches is regarded since their number and location significantly affect the solution of the placement problem. The proposed model is developed in the mixed integer programming format which can be effectively solved via available solvers. The effectiveness of the proposed model is demonstrated through a test system and a real-life distribution network. The obtained results indicate the great performance of the model in enhancing service reliability as well as reducing system costs.