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With rapidly developing of the distribution networks the rate of the earth fault increases sharply. Aiming to fault location for distribution networks, many techniques are proposed and applied in distribution networks throughout the world. However, until now the technology for precise fault point location has not been successfully implemented in engineering practice. Traveling wave based methods as common techniques are widely applied in transmission line protection for locating fault point. However, these methods face severe challenge in fault location for distribution networks. The main reason is that the intermittent arc fault easily results in failure of detecting inceptive travelling wave and this intermittent arc is a common earth fault in distribution networks compared with transmission networks. In this paper, a simplified distribution line is built by making reference to the two parallel lossless transmission lines system. Then, the intermittent arc effects on traveling wave based method are modeled and discussed. Finally, the reason why these travelling wave based methods are hard to locate fault point precisely is illustrated. [ABSTRACT FROM AUTHOR]

This paper studies online travelling wave methods for fault location on a crossbonded cable system using sheath currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. At 31.4 km, all cables were accessible which made it possible to apply a fault using an arc free breaker and measure the travelling waves at each end of the cable. On a crossbonded cable system, the sheaths are short circuited and grounded at both ends. This makes possible the use of low voltage Rogowski coils if the sheath currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and a visual inspection method are used and the accuracy is compared. Field measurements and simulations are compared for testing the reliability of using simulations for studying fault location methods. [ABSTRACT FROM AUTHOR]

This paper proposes a new high fault coverage test approach for short faults in Network on Chip communication channels. The proposed approach consists of a built in self-test as well as a Packet/flit Comparing Module (PCM) embedded in the network adapter and a router, respectively. The approach is mainly characterized by the fact that, the detection, location, and routing table updating processes are simultaneously carried out after which the test time is minimized. The approach with high scalability leads to 100% test coverage and 89.5% capability of diagnosing faulty channels in one round (two phases). The simulation results show that the approach hardware and time cost is optimized compared with the previous methodologies. [ABSTRACT FROM AUTHOR]

This paper presents an approach to single line-to-ground fault location in a power distribution system based on the time lag of different modal components . It is a single-ended method applicable to unsynchronized measurements. The fault location formulation is derived by analyzing the traveling wave propagation characteristic in a distributed parameter model. To tackle the key problem of ground-mode velocity estimation, an iterative velocity method based on prior knowledge is first proposed. Since the practical measurements are not ideal because of sensor accuracy and nonequivalent transient response, fuzzy neural network is utilized to process traveling wave data acquired at multiple measurements to get an error-tolerant effect. Furthermore, electromagnetic transient simulations for a 34-bus test feeder system under various conditions of fault resistances, inception angles, and distributed generator access reveal the robust estimation of fault location. The performance of the proposed method is also validated by simulations with noisy and noise-free measurements. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

• Analysis for Hybrid-HVDC transmission line fault evolution process. • Adaptive criterion for judging when the fault evolves into the AC feed-in stage. • Equivalent characteristic impedance-based Hybrid-HVDC line fault location principle. • Extraction algorithm for the characteristic component at the AC feed-in stage. • Comparison of the proposed fault location principle with the existing methods. Aiming at the transmission line fault in Hybrid-HVDC system, this paper divides the fault evolution process into different stages according to the difference of transition resistance at the fault point and the conduction state change of power electronic devices, emphatically analyzes the conversion conditions between different stages, and proposes an adaptive criterion for judging the moment when the fault evolves into AC feed-in stage. Based on the characteristic component of electrical quantities at AC feed-in stage, this paper defines the equivalent characteristic impedance at any point of transmission line, derives the functional relationship between the fault distance and the equivalent characteristic impedance at inverter side DC bus, and locates the fault point according to this relationship. In order to extract the characteristic component of electrical quantities, a characteristic component extraction algorithm is studied, it can effectively eliminate the influence of constant DC component and decaying aperiodic component. This paper builds the Hybrid-HVDC system simulation model and carries out simulation experiments on PSCAD/EMTDC, and compares the proposed fault location principle with the existing methods. The simulation results verify the effectiveness of the adaptive criterion for judging the AC feed-in stage starting moment and the proposed fault location principle. [ABSTRACT FROM AUTHOR]

Through an earlier experimental study, an integrated fault classification approach was suggested for machines operating at different speeds. The suggested method was observed to separate faults adequately, which can lead to fault diagnosis. However, theoretical understanding of the proposed methods is important to further enhance the confidence of the earlier experimental study. Hence, simplified mathematical simulations of different rotor faults are carried out and used to test the earlier proposed classification technique in this paper. Observations in the orbit, spectra and fault classification diagrams are consistent with the previous experimental case. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method for fault location in distribution networks using compressive sensing. During fault and prefault voltages are measured by smart meters along the feeders. The voltage sag vector and impedance matrix produce a current vector that is sparse enough with one nonzero element. This element corresponds to the bus at which a fault occurs. Due to the limited number of smart meters installed at primary feeders, our system equation is underdetermined. Therefore, the \ell ^1-norm minimization method is used to calculate the current vector. Primal-dual interior point (PDIP) and the log barrier algorithm (LBA) are utilized to solve the optimization problem with and without measurement noises, respectively. Our proposed method is implemented on a real 13.8-kV, 134-bus distribution network when single-phase, three-phase, double-phase, and double-phase-to-ground short circuits occur. Simulation results show the robustness of the proposed method in noisy environments and satisfactory performance for various faults with different resistances. [ABSTRACT FROM AUTHOR]

In this paper, a fault tolerance based QoS (Quality of Services) scheduling using HTF (Hash Table Functionality) in Social Grid Computing (SGC) is introduced, where HTF is used as the underlying mechanism in SGC to logically manage the locations of the devices. Fault tolerance based QoS scheduling consists of four sub-scheduling algorithms: Unauthorized-user filtering, Grid service delivery, QoS provisioning, and Replication and load-balancing. Under the proposed scheduling, a device is used as a resource for providing Grid services, faults caused due to reason like user mobility are tolerated and user requirements for QoS are considered. Simulations include the scheduling by with and without HTF. The simulation results show that our proposed scheduling algorithm enhances Grid service execution time, finish time, reliability and reduces the Grid service error rate. [ABSTRACT FROM AUTHOR]

In this work, a fault diagnosis methodology termed VisualBlock-Fuzzy Inductive Reasoning, i.e. VisualBlock-FIR, based on fuzzy and pattern recognition approaches is presented and applied to PEM fuel cell power systems. The innovation of this methodology is based on the hybridization of an artificial intelligence methodology that combines fuzzy approaches with well known pattern recognition techniques. To illustrate the potentiality of VisualBlock-FIR, a non-linear fuel cell simulator that has been proposed in the literature is employed. This simulator includes a set of five fault scenarios with some of the most frequent faults in fuel cell systems. The fault detection and identification results obtained for these scenarios are presented in this paper. It is remarkable that the proposed methodology compares favorably to the model-based methodology based on computing residuals while detecting and identifying all the proposed faults much more rapidly. Moreover, the robustness of the hybrid fault diagnosis methodology is also studied, showing good behavior even with a level of noise of 20 dB. [ABSTRACT FROM AUTHOR]