Fault Location System Research Articles

Development of an advanced transmission line fault location system. II. Algorithm development and simulation

For pt.I see ibid., vol.7, no.4, p.1963-71 (1992). The authors describe the solution techniques, system modeling considerations, and simulation studies performed as a part of the development of an advanced transmission line fault location system intended for use on the New York Power Authority's system. The Power Authority's Moses-Adirondack 230 kV lines were selected as a testbed for the study. A reduced model of the transmission system around the Moses-Adirondack lines was developed, and a number of electromagnetic transients program (EMTP) cases were run to establish simulated voltage and current information as fed to the fault location system. Sensitivity studies were performed to investigate the impact of various system models, hardware features, and system conditions on fault location accuracy. >

Real-time expert system for fault location on voltage underground distribution cables

To ensure minimum loss of system security and revenue it is essential that faults on underground cable systems be located and repaired rapidly. Currently in the UK, the impulse current method is used to prelocate faults, prior to using acoustic methods to pinpoint the fault location. The impulse current method is heavily dependent on the engineer's knowledge and experience in recognising/interpreting the transient waveforms produced by the fault. The development of a prototype real-time expert system aid for the prelocation of cable faults is described. Results from the prototype demonstrate the feasibility and benefits of the expert system as an aid for the diagnosis and location of faults on underground cable systems.

Development of an advanced transmission line fault location systems. I. Input transducer analysis and requirements

As part of the development of an advanced, more consistently accurate transmission line fault location system (AFLS), an evaluation of the performance and requirements for voltage and current input transducers was made. Measurements of current transformer and burdens were made, and computer models of the steady-state and transient responses were developed. Burdens from the electromechanical relaying and metering equipment in the secondary circuits were found to be large enough to cause transient distortion of the current waveforms for some fault causes, and would not meet the stringent requirements for an AFLS. A recommendation was made to place the AFLS in the primary relaying circuits, where electronic relays having low burdens are installed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Fault location system for electric power transmission lines based on fuzzy knowledge base

Fault location system for electric power transmission lines based on fuzzy knowledge base

ファジー知識ベースに基づく送電線の故障区間標定システム

ファジー知識ベースに基づく送電線の故障区間標定システム

A fault location system for a time of flight detector array

We describe a fault location system currently under development at Lawrence Berkeley Laboratory for the HISS Time of Flight Wall. The system identifies malfunctioning components by monitoring the detector output channels. For single component failures, a fast simple, lookup procedure reduces the number of suspected components to at most three out of 2500 possible. The system remembers failed components, so that it continues to locate new failures even when several components are in a failed state. The system can also handle partial component failures such as might be caused by the partial failure of a large power supply module. The approach shows promise for more complex detector systems. Plans for a rule-based, “expert system”, analysis to further narrow the list of suspected components are presented.

New Fault Location System for Power Transmission Lines Using Composite Fiber-Optic Overhead Ground Wire (OPGW)

This paper describes a new method of locating the section where an electrical fault occurs on a power transmission line using Composite Fiber-Optic Overhead Ground Wires (OPGWs). This fault location (FL) method locates the fault section by measuring the current induced in the ground wire (GW), i.e., OPGW in this system. The OPGW currents are measured at many towers which divide the power line into sections. Data is transmitted to a central monitoring station as an optical signal through the optical fibers included within OPGW. Prior to the development of this new FL system, a simulation of power line faults using Electro-Magnetic Transients Program (EMTP) was conducted. As a result, the following two points were clarified; 1) Since OPGW current changes with line condition, it is quite difficult to define a fixed threshold level to locate fault sections accurately. 2) The distribution pattern of OPGW current along the power line has clear features around the fault point, so it is possible for electric power engineers to find the fault section by relative comparison. Therefore, the FL algorithm to be developed should have the capability of finding out the fault section with a human-like method of recognition. Fuzzy Theory, an attempt to include this kind of humanlike way of thinking into computers, was investigated and a new FL method applying this theory was developed. Fig. 1 shows the OPGW current distribution pattern of a typical grounding fault calculated by EMTP as an example.

New fault location system for power transmission lines using composite fiber-optic overhead ground wire (OPGW)

A fault location (FL) method using composite fiber-optic overhead ground wires (OPGWs) was developed to find out where electrical faults occur on overhead power transmission lines. This method locates the fault section by detecting the current induced in the ground wire, i.e. the OPGW in this system. Since detected fault information is essentially uncertain, the fault information is treated in the proposed FL method as a current distribution pattern throughout the power line, and fuzzy theory is applied to realize the manner of fault location used by electrical power engineers. It was confirmed by computer simulations that the fault section can be accurately located using this method under various conditions. This FL system was applied to several commercial power transmission lines and successfully located the sections where electrical faults occurred.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

4713815 Automatic fault location system for electronic devices

This paper addresses a study on simulated space radiation effects on charge-coupled devices (CCD). An implicit method of assessing the performance degradation and field reliability of CCDs operated in natural ionizing-radiation ambients is devised via test studies using an electrical overstress parameter to represent the ionizing radiation dosage equivalently. Relevant cumulative degradation due to accelerated aging performed on a set of commercially available CCD is analyzed to establish the endurance coefficient of device(s). The proposed method is devoid of handling hazardous ionizing radiation sources and also enables fast reliability predictions. The test results are discussed.

New measurement system for fault location in optical waveguide devices based on an interferometric technique

A new measurement system for fault location in optical waveguide devices is presented. The system consists of a fiber-optic Mach-Zehnder and a bulk-type Michelson interferometers. The spatial resolution of the scatter distribution is <380 microm, which is limited by the averaging time. The minimum detectable backscattered power is -116 dB relative to the light power propagating in the waveguides. Preliminary experimental results using single-mode fibers <10 cm long are demonstrated.

Remote control signal for submarine optical repeater fault location systems

AbstractThis paper studies the remote control signal for submarine digital optical repeater fault location systems. The conditions to be satisfied by a submarine optical repeater fault location system are shown first and then a practical fault location system is proposed. The remote control signal is composed of a mark density modulated pulse stream whose on‐off is controlled by pulse width modulated command codes. This signal achieves performance improvement even when there are main transmission line errors, code identification of repeater, and simplification of supervisory control circuit. This remote control signal is validated through a transmission experiment using 445 Mb/s submarine optical repeater, and the robustness against main transmission errors and the error detection ability of transmission line errors are clarified.

Repeater Fault Location for a Submarine Optical Fiber Cable Transmission System

This paper introduces a repeater fault location system for a repeated submarine optical fiber transmission system of 400 Mbits/ s at 1.3μm. The repeater fault location system is used in an out-of-service test. The fault locator transmits a test signal via a main optical fiber line, in order to make a loop-back path in one of the repeaters for returning the test signals via another main optical fiber line and to measure the bit error rate (BER) of the interrogated repeater. The test signal is a kind of pseudorandom signal that includes a low frequency component, which is assigned to the repeater as a supervisory frequency tone (SVT) signal. The BER is measured by counting the number of low frequency signal phase inversions in a time. This paper first describes the test signal generating method, SVT frequency allocation, and the filter design installed in a repeater. Next, there is a discussion of how the capability of the repeater fault locator has been experimentally verified by using two submarine repeaters, including four regenerative repeater units and three submarine optical fiber cables. As a result, a BER of less than <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5 \times 10^{-6}</tex> is accurately measured.

Fault Location in SF6 Insulated Substations Using Thermal Techniques

This paper presents the results of a study of non-invasive fault location techniques in gas insulated substations. The applications of infrared thermal imaging system and temperature sensitive paint to locate in-service faults with power follow-through were demonstrated. The infrared fault location system can be applied to existing substation without retrofitting. Detection sensitivities and system parameters are presented.

Fault Location System for Transmission-Type Cable

A fault location system was developed for locating nonlinear faults on transmission-type cable. The fault locator measures the distance from terminal to fault as a fraction of the total cable length. A forward wave radar principle is used. The forward wave is generated by the cable breakdown at the fault. Laboratory and field tests indicate that nonlinear faults can be located to within ±10 m. Equipment modifications have been made to measure cable lengths to 10 km and longer. Further field tests and demonstration tests are planned.

Simplified ATPG and analog fault location via a clustering and separability technique

Automatic test program generation (ATPG) for analog system fault location is considered and a procedure for generating a set of tests for a linear network using gain and phase measurements from input-output measurements only is presented. The best subset of features for fault diagnosis is selected via a discriminatory index. Each feature subset selected during the optimization procedure is tested for enhanced separability of observation space for faults and the efficiency of the subset for diagnosis is indexed using a confidence level. The fault matrix formed using the selected feature subset is analized for cluster formation, the separability measure introduced is used to group the fault cases and a reduction of the cases to be considered on-line is obtained. In fault location, a fault is identified to a specific group which then is further located to the individual component and is carried out for varying production tolerances.

Computer aided feature selection for enhanced analogue system fault location

A digital computer based technique for the selection of optimum test frequencies for fault diagnosis of analogue systems is presented. Gain and phase deviations from the nominal system response for changes in component values are evaluated and the recognition matrix is established which in turn is normalized and made sparse. The heuristic optimization technique developed is applied to the sparse recognition matrix to select the best subset of features via a discriminatory index of measurement points by adding or discarding features until the optimum is found. The efficiency of the selected feature set is measured by the confidence level formally incorporated in the algorithm and which is found to correlate well with the actual diagnosability of faults for a simulation of varying fault levels and including varying production tolerances for the non-faulty components. Actual fault location is implemented using the nearest neighbour rule, which is complimentary to the feature selection technique. Only three measurements are found to be sufficient to achieve a high level of diagnosability. The simulation of 91,000 faulty 7 component passive circuits has been undertaken to verify the procedure, which may now be applied equally well to larger scale systems using input-output measurements only, or, alternatively on sub-systems of comparable size to the sample circuit which have been isolated by special electronic partitioning devices as recently proposed for the fault location in television receivers during the manufacturing process.

Application of the Multiharmonic Fourier Filter to Nonlinear System Fault Location

The Fourier Response Analyser (FRA) has become a widely used and accepted instrument with clearly defined noise and harmonic rejection characteristics. In a nonlinear system, however, the higher harmonics contain useful information on the system under test which this paper shows can be used by the test designer to assess system quality and pinpoint nonlinear fault locations if the system is classified as sick. Backlash, saturation, and deadzone conditions are thereby detected in an analogue simulation model previously matched to a hardware servomechanism. The higher harmonic components are estimated by a special version of the FRA incorporating the Multiharmonic Fourier Filter (MFF) which is based on the same correlation principle as is used to detect the fundamental response.

Fault location system in autotransformer feeding circuit of ac electric railways

The distance vs. reactance curve of the autotransformer feeding circuit as used for the Sanyo line is not linear but approximately parabolic. Further, it differs from circuit to circuit. For this reason, conventional fault locators can not be used for the autotransformer feeding circuit. An attempt was made to measure the distance between the feeding point and the fault point by combining feeding voltages with feeder currents in a suitable way. It was found that the neutral current ratio of the autotransformer is proportional to the distance. The neutral current ratio type fault locator has been developed on the basis of this principle. This system was applied to the Okayama-Hakata section (393 km) of the Sanyo line for the first time and since then, has continually worked very satisfactorily. This paper describes the impedance and neutral current ratio characteristics of the autotransformer feeding circuit and outlines the neutral current ratio type fault locator and its operating records.

ATき電回路における故障点標定システム

ATき電回路における故障点標定システム

Automated Fault Location System for Digital Circuits Production

The automated fault location system for digital circuits in their production may be considered as the entirety of hardware, software and diagnostic data. The diagnosis object is a hybrid LSI circuit. The diagnosis process essentially involves simulation data. The problem of finding the optimal decomposition of the initial fault set provided decrease of diagnostic data amount, and the problem of optimization of diagnosis results analysis are formulated. The diagnostic resolution is used as optimization criterion. Methods for decoding diagnostic experiment's results are developed, possibility of multiple faults and model inconsistency being taken into account. Some experiment's results are given.