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Showing papers on "Fault indicator published in 2008"


Journal ArticleDOI
TL;DR: In this article, performance of 10 fault location methods for power distribution systems has been compared using only measurements of voltage and current at the substation, and the results for several scenarios defined by significant values of the fault location and impedance.

262 citations


Journal ArticleDOI
TL;DR: In this paper, a combined wavelet-support vector machine (SVM) technique for fault zone identification in a series compensated transmission line is presented, which uses the samples of three line currents for one cycle duration to accomplish this task.
Abstract: This paper presents a combined wavelet-support vector machine (SVM) technique for fault zone identification in a series compensated transmission line. The proposed method uses the samples of three line currents for one cycle duration to accomplish this task. Initially, the features of the line currents are extracted by first level decomposition of the current samples using discrete wavelet transform (DWT). Subsequently, the extracted features are applied as inputs to a SVM for determining the fault zone (whether the fault is before or after the series capacitor, as observed from the relay point). The feasibility of the proposed algorithm has been tested on a 300-km, 400-kV series compensated transmission line for all the ten types of faults through detailed digital simulation using PSCAD/EMTDC. Upon testing on more than 25000 fault cases with varying fault resistance, fault inception angle, prefault power transfer level, percentage compensation level, and source impedances, the performance of the developed method has been found to be quite promising.

165 citations


Journal ArticleDOI
Yuan Liao1
TL;DR: In this paper, a fault location approach for single-circuit lines utilizing only voltage measurements from one or two buses, which may be distant from the faulted line, is presented.
Abstract: Diverse transmission line fault location algorithms have been proposed in the past depending on measurements available. Existing algorithms usually require measurements captured from buses of a faulted line. By taking advantage of the bus-impedance matrix technique, this paper presents a possible fault location approach for single-circuit lines utilizing only voltage measurements from one or two buses, which may be distant from the faulted line. With the addition of a fictitious bus where the fault occurs, the transfer impedances of this bus and other buses are revealed as a function of the fault location. Based on the relationship between the bus voltage change due to fault and the transfer impedance, the fault location can be derived. Shunt capacitance of the line is ignored first and then fully considered based on distributed parameter line model. Electromagnetic transients program simulation studies have shown quite encouraging results.

122 citations


Journal ArticleDOI
TL;DR: In this paper, a frequency domain approach for digital relaying of transmission line faults mitigating the adverse effects of power swing on conventional distance relaying is presented, which is different from conventional algorithms that are based on deterministic computations on a well defined model for transmission line protection.
Abstract: In the present milieu, changes in regulations and the opening of power markets have manifested in the form of large amount of power transfer across transmission lines with frequent changes in loading conditions based on market price. Since conventional distance relays may consider power swing as a fault, tripping because of such malfunctioning would lead to serious consequences for power system stability. A frequency domain approach for digital relaying of transmission line faults mitigating the adverse effects of power swing on conventional distance relaying is presented. A wavelet-neuro-fuzzy combined approach for fault location is also presented. It is different from conventional algorithms that are based on deterministic computations on a well-defined model for transmission line protection. The wavelet transform captures the dynamic characteristics of fault signals using wavelet multi-resolution analysis (MRA) coefficients. The fuzzy inference system (FIS) and the adaptive-neuro-fuzzy inference system (ANFIS) are both used to extract important features from wavelet MRA coefficients and thereby to reach conclusions regarding fault location. Computer simulations using MATLAB have been conducted for a 300 km, 400 kV line and results indicate that the proposed localisation algorithm is immune to effects of fault inception, angle and distance. The results contained here validate the superiority of the ANFIS approach over the FIS for fault location.

121 citations


Journal ArticleDOI
TL;DR: In this paper, an extensive fault location model for underground power cable in distribution system using voltage and current measurements at the sending-end is proposed, which is an iterative process to determine a faulted section from the network.
Abstract: This paper proposes an extensive fault location model for underground power cable in distribution system using voltage and current measurements at the sending-end. First, an equivalent circuit that models a faulted underground cable system is analyzed using distributed parameter approach. Then, the analysis of sequence networks in three-phase network is obtained by applying the boundary conditions. This analysis is used to calculate a fault distance in single section using voltage and current equations. The extension to multi-section is further analyzed based on Korean distribution systems. This method is an iterative process to determine a faulted section from the network. Finally, the case studies are evaluated with variations of fault distance and resistance, which also includes the evaluation of its robustness to load uncertainty.

112 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a novel fault diagnosis scheme for power distribution systems, composed by three different processes: fault detection and classification, fault location, and fault section determination.
Abstract: Power distribution automation and control are important tools in the current restructured electricity markets. Unfortunately, due to its stochastic nature, distribution systems faults are hardly avoidable. This paper proposes a novel fault diagnosis scheme for power distribution systems, composed by three different processes: fault detection and classification, fault location, and fault section determination. The fault detection and classification technique is wavelet based. The fault-location technique is impedance based and uses local voltage and current fundamental phasors. The fault section determination method is artificial neural network based and uses the local current and voltage signals to estimate the faulted section. The proposed hybrid scheme was validated through Alternate Transient Program/Electromagnetic Transients Program simulations and was implemented as embedded software. It is currently used as a fault diagnosis tool in a Southern Brazilian power distribution company.

112 citations


Journal ArticleDOI
TL;DR: In this paper, a feed forward neural network is used to identify the fault location and then protection of the system for a wide range of system conditions, and the predicted results from the algorithm prove the effectiveness of the proposed procedure for identifying fault location.

109 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis, including gear fault, rolling contact bearing, journal bearing, flexible coupling faults, and electrical machine fault.
Abstract: The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

96 citations


Journal ArticleDOI
TL;DR: In this article, a wind turbine model is built based on the closed loop identification technique, where the wind dynamics is included in the model, and the fault detection issue is investigated based on residual generated by Kalman filter.

94 citations


Journal ArticleDOI
TL;DR: The passivity theory is introduced into the fault tolerance analysis for switched systems and a ldquoglobal passivityrdquo concept is proposed which means that the total energy stored by the switched system is less than thetotal energy supplied from the outside.
Abstract: In this brief, we introduce the passivity theory into the fault tolerance analysis for switched systems. We propose a ldquoglobal passivityrdquo concept which means that the total energy stored by the switched system is less than the total energy supplied from the outside. The individual passivity of each mode is not required, and the stability of the system can be achieved via the global energy dissipativity in the presence of faults. We further provide a ldquoperiodic fault tolerant passivityrdquo to check the fault tolerance easily. The obtained results are extended to feedback interconnected systems. A switched RLC circuit example is taken to illustrate the efficiency of the proposed results.

94 citations


Journal ArticleDOI
TL;DR: It is shown that fault detectors can be synthesized that are robust to variations in the task, and it is shown how a fault detector can be trained to allow one robot to detect faults that occur in another robot.
Abstract: In this paper, we study a new approach to fault detection for autonomous robots. Our hypothesis is that hardware faults change the flow of sensory data and the actions performed by the control program. By detecting these changes, the presence of faults can be inferred. In order to test our hypothesis, we collect data from three different tasks performed by real robots. During a number of training runs, we record sensory data from the robots while they are operating normally and after a fault has been injected. We use back-propagation neural networks to synthesize fault detection components based on the data collected in the training runs. We evaluate the performance of the trained fault detectors in terms of number of false positives and time it takes to detect a fault. The results show that good fault detectors can be obtained. We extend the set of possible faults and go on to show that a single fault detector can be trained to detect several faults in both a robot's sensors and actuators. We show that fault detectors can be synthesized that are robust to variations in the task, and we show how a fault detector can be trained to allow one robot to detect faults that occur in another robot.

Journal ArticleDOI
TL;DR: In this paper, an agent-based protection scheme for distribution networks with distributed generators is presented, where relay agents, located at the boundaries of these segments, can determine the direction of fault currents using the transients generated by the fault.
Abstract: This paper presents an agent-based protection scheme for distribution networks with distributed generators. The distribution network is divided into several network segments. The relay agents, which are located at the boundaries of these segments, can determine the direction of fault currents using the transients generated by the fault. Fault directions determined by the relay agents located at different points of the network are combined to determine the faulted segment. A fault direction identification technique, which uses the wavelet coefficient of the measured line currents, was developed for relay agents. The performance of the proposed protection scheme is investigated through simulation of a benchmark medium-voltage distribution system.

Journal ArticleDOI
TL;DR: In this paper, a universal fault location technique for N-terminal transmission lines based on synchronized phasor measurement units is proposed, which provides an analytical solution and its computational burden is very low since it does not require iterative operations.
Abstract: This paper presents a universal fault location technique for N-terminal transmission lines based on synchronized phasor measurement units. The development of the technique is based on two-terminal fault location technique. The proposed algorithm is different from traditional multiterminal fault location techniques. We apply two-terminal fault location technique to N-terminal transmission lines and propose a novel fault section selector/fault locator. The proposed method has a very good tolerance. The proposed approach provides an analytical solution and its computational burden is very low since it does not require iterative operations. An extensive series of simulations were conducted to verify the accuracy of the proposed algorithm. The average fault location error under various fault conditions is well below 1%.

Journal Article
TL;DR: In this article, a fault detection and isolation module is firstly built, which can produce an alarm when there is a fault in the system and also tell us which sensor has a fault.
Abstract: A general active fault-tolerant control framework is proposed for nonlinear systems with sensor faults. According to their identifiability, all sensor faults are divided into two classes: identifiable faults and non-identifiable faults. In the healthy case, the control objective is such that all outputs converge to their given set-points. A fault detection and isolation module is firstly built, which can produce an alarm when there is a fault in the system and also tell us which sensor has a fault. If the fault is identifiable, the control objective remains the same as in the healthy case; while if the fault is non-identifiable, the control objective degenerates to be such that only the healthy outputs converge to the set-points. A numerical example is given to illustrate the effectiveness and feasibility of the proposed method and encouraging results have been obtained.

Patent
10 Nov 2008
TL;DR: In this paper, a convex optimization problem for each fault hypothesis is formulated and the highest likelihoods and corresponding parameter estimates are transmitted to a display device or an automated decision and control system.
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.

Journal ArticleDOI
TL;DR: It is theoretically and experimentally shown that the proposed method can determine the normalized magnitude and phase information of the fault signatures even in the presence of noise, where the noise amplitude is several times higher than the signal itself.
Abstract: In this paper, a digital signal processor-based phase-sensitive motor fault signature detection technique is presented. The implemented method has a powerful line current noise suppression capability while detecting the fault signatures. Because the line current of inverter-driven motors involve low-order harmonics, high-frequency switching disturbances, and the noise generated by harsh industrial environment, the real-time fault analyses yield erroneous or fluctuating fault signatures. This situation becomes a significant problem when the signal-to-noise ratio of the fault signature is quite low. It is theoretically and experimentally shown that the proposed method can determine the normalized magnitude and phase information of the fault signatures even in the presence of noise, where the noise amplitude is several times higher than the signal itself. Since it has low computational burden, the developed algorithm is embedded to the motor control program without degrading drive performance. Therefore, it is implemented without any additional cost using readily available drive processor and current sensors.

Journal ArticleDOI
TL;DR: In this article, a supervisor system, able to diagnose different types of faults during the operation of a proton exchange membrane fuel cell is introduced, which is developed by applying Bayesian networks, which qualify and quantify the cause-effect relationship among the variables of the process.

Journal ArticleDOI
TL;DR: A rigorous isolability analysis is presented via the use of the so-called fault mismatch functions, which are defined between pairs of possible faults.

Journal ArticleDOI
TL;DR: In this article, the authors considered fault detection, isolation and reconstruction problem for descriptor systems with actuator faults and sensor faults, respectively, and the main objective of this work was to attempt the reconstruction of the faults.
Abstract: In this paper, we consider fault detection, isolation and reconstruction problem for descriptor systems with actuator faults and sensor faults, respectively. When actuator faults exist in the system, the fault detection and isolation (FDI) problem is solved through an unknown input observer regarding remaining faults excluded a specified fault as unknown inputs. Whereas, in existing sensor faults, the fault detection is only achieved by the unknown input observer and residual signals. Since the derivative signal of sensor fault is generated in the error dynamics between the actual system and the derived observer. The main objective of this work attempts the reconstruction of the faults. The reconstruction can be achieved by sliding mode observer including feedforward injection map and compensation signal. Finally, the isolation problem of sensor faults is solved by reconstructing all of the faults.

Patent
14 Apr 2008
TL;DR: In this article, a fault processing system and method for quickly and accurately diagnosing a fault and autonomously processing the fault, based on interdependencies between various devices, networks, systems, and services in home network environments, is provided.
Abstract: There are provided a fault processing system and method for quickly and accurately diagnosing a fault and autonomously processing the fault, based on interdependencies between various devices, networks, systems, and services in home network environments, the method including: establishing fault detection rules for detecting faults belonging to respective fault types defined for each situation by classifying faults occurring in the home network environments, fault diagnosis rules for diagnosing a fault type of a fault, and fault processing rules defining a method of solving a fault for each fault type; collecting state information of devices, networks, services, and the system in the home network environments and detecting a fault based on the fault detection rules; diagnosing the fault type of the detected fault by applying the fault diagnosis rules; and processing the detected fault based on the fault processing rules according to the diagnosed fault type.

Proceedings ArticleDOI
17 Mar 2008
TL;DR: In this article, an alternative and novel approach based on monitoring disturbances in the voltages seen at the generator's terminals to protect the generator and the associated network is described. But the authors consider the application of this technique to a three-phase network and present simulation results to a variety of different faults.
Abstract: The protection of micro-grids containing distributed generation using solid state converters can not depend on monitoring the fault current to detect short circuit faults. In order to protect the semi-conductor devices, the output current from the converter is generally limited to about twice the unit's full load current. This paper describes an alternative and novel approach based on monitoring disturbances in the voltages seen at the generator's terminals to protect the generator and the associated network. It considers the application of this technique to a three-phase network and presents simulation results to a variety of different faults. These demonstrate the operation of the protection scheme and its ability to handle the different types of faults.

Proceedings ArticleDOI
07 Jul 2008
TL;DR: A new SystemC-based fault injection technique that has improved fault representation in visible and on-the-fly data and signal registers is proposed that has fast simulation speed, better fault representation, while maintaining simplicity and minimum intrusion.
Abstract: In this paper, we propose a new SystemC-based fault injection technique that has improved fault representation in visible and on-the-fly data and signal registers. The technique is minimum intrusive since it only requires replacing the original data or signal types to fault injection enabler types. We compare the proposed simulation technique with recently reported SystemC-based techniques and show that our technique has fast simulation speed, better fault representation, while maintaining simplicity and minimum intrusion. We demonstrate fault injection capabilities in a behavioural SystemC description of MPEG-2 decoder using proposed technique and show that up to 98.9% fault representation within data and signal registers can be achieved.

Patent
01 Jul 2008
TL;DR: A hub device, memory system, and method for providing a cascade interconnect memory system with enhanced reliability is described in this article, where the hub device includes an interface to a high-speed bus for communicating with a memory controller.
Abstract: A hub device, memory system, and method for providing a cascade interconnect memory system with enhanced reliability The hub device includes an interface to a high-speed bus for communicating with a memory controller The memory controller and the hub device are included in a cascade interconnect memory system and the high-speed bus includes bit lanes and one or more clock lanes The hub device also includes a bi-directional fault signal line in communication with the memory controller and readable by a service interface The hub device also includes a fault isolation register (FIR) for storing information about failures detected at the hub device, the information including severity levels of the detected failures In addition, the hub device includes error recovery logic for responding to a failure detected at the hub device Responding to the error includes recording a severity level of the failure in the FIR and taking an action at the hub device that is responsive to the severity level of the failure The action includes one or more of fast clock stop, setting the bi-directional fault indicator, setting cyclical redundancy code (CRC) bits and transmitting them to the memory controller, re-try, sparing out a bit lane and sparing out a clock lane

Proceedings ArticleDOI
25 May 2008
TL;DR: This work couple the calculation of the critical size of a small-delay fault with the computation of the resistance range of the corresponding resistive-open defect for which this size is exceeded, and is able to extend probabilistic fault coverage metrics initially developed for static resistive bridging faults to small- delay defects.
Abstract: We present a simulator which determines the coverage of small-delay faults, i.e., delay faults with a size below one clock cycle, caused by resistive-open defects. These defects are likely to escape detection by stuck-at or transition fault patterns. For the first time, we couple the calculation of the critical size of a small-delay fault with the computation of the resistance range of the corresponding resistive-open defect for which this size is exceeded. By doing so, we are able to extend probabilistic fault coverage metrics initially developed for static resistive bridging faults to small-delay defects.

Patent
25 Jan 2008
TL;DR: In this paper, the authors present a method of generating fault indication in a feeder remote terminal unit for a power distribution automation system, where the phase of a zero-sequence current is compared with that of a 0-sequence voltage.
Abstract: The present invention relates to a method of generating fault indication in a feeder remote terminal unit for a power distribution automation system. The method is performed in a distribution system that includes a plurality of feeder remote terminal units, which are installed in respective sections of a line and are configured to measure voltage, current and a phase difference of the line, and a central control unit for determining whether a fault occurs and controlling operation of the feeder remote terminal units. In the method, phases are measured by each of the feeder remote terminal units. The phase of a zero-sequence current is compared with that of a zero-sequence voltage. A direction of a fault current is calculated, and fault indication information is generated in the calculated direction of the fault current.

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors proposed fault location formulas using synchronized sequence measurements, where zero-sequence voltages and currents at two terminals of faulted line are applied to fault location, and positive-sequence measurements are used for three-phase faults.

Proceedings ArticleDOI
RN Argile1, Barrie Mecrow1, Dave Atkinson1, Alan G. Jack1, P Sangha1 
02 Apr 2008
TL;DR: This paper examines fault tolerant power converter topologies and develops a technique for producing data to compare the reliability of topologies, following which reliability curves and failure rate data is constructed.
Abstract: This paper examines fault tolerant power converter topologies and develops a technique for producing data to compare the reliability of topologies. The various states of fault-tolerant systems are modelled, following which reliability curves and failure rate data is constructed.

Proceedings ArticleDOI
20 Jul 2008
TL;DR: In this paper, a fault location algorithm for untransposed parallel transmission lines that uses only the voltages and currents at the local end is proposed, where the fault current can be represented in terms of the fault distance.
Abstract: Summary form only given: This paper proposes a fault location algorithm for ultra-high-voltage untransposed parallel transmission lines that uses only the voltages and currents at the local end. The proposed algorithm uses the voltage equation for the faulted phase of the faulted line. The equation contains the fault distance, fault resistance, and fault current. To obtain the fault current, Kirchhoffpsilas voltage law is applied on the loops of three phases consisting of the faulted line and the adjacent parallel line. The fault current can be represented in terms of the fault distance. Inserting the fault current into the voltage equation results in an equation that contains only two parameters, i.e., the fault distance and fault resistance. The fault distance is estimated by solving the equation. Test results indicated that the algorithm accurately estimates the fault distance regardless of the fault resistance and mutual coupling effects.

Proceedings ArticleDOI
01 Dec 2008
TL;DR: In this article, a fault identification and location technique using wavelet multi-resolution approach for radial distribution systems is proposed and the effectiveness of the proposed approach is demonstrated on 7-node and 19-node three-phase test systems.
Abstract: Electrical distribution system, which is the largest portion of networks, acts as a final power delivery path to the end users. Hence, ensuring its efficient and reliable operation is an extremely important and challenging task. Utilities, all over the world are competing for improvement in service to consumers, and the area of fault detection and diagnosis in distribution systems have attracted the significant attention of researchers in last few decades. With availability of inadequate system information and presence of high impedance faults, locating faults in a distribution system pose a major challenge to the utility operators. Most of the previous work on fault identification and location concentrated on estimating the status of circuit breakers and relays with aid of some algorithmic approaches. In this paper, a fault identification and location technique using wavelet multi-resolution approach for radial distribution systems are proposed. The current measurements at the substation, available in the distribution network have been utilized and the effectiveness of the proposed approach is demonstrated on 7-node and 19-node three-phase test systems.

Patent
Masaya Ichinose1, Shinya Ohara1, Motoo Futami1, Mitsugu Matsutake1, Hiromitsu Sakai1 
28 May 2008
TL;DR: In this article, a doubly-fed generator is used to produce a reactive current from a wind power generator to an electric power system without destroying equipment of the wind power generation system.
Abstract: A wind power generation system temporarily stops a power converter when a system disturbance occurs, and reactivates the power converter after detecting a solution of the problem of an influence (overcurrent of a stator, direct current component of a stator, overcurrent of a rotor, etc.) of a fault occurring in a doubly-fed generator during a system fault. During a system fault, a reactive current can be safely output from a doubly-fed generator to an electric power system without destroying equipment of the wind power generation system.