An intermittent pulsed carrier signal having a frequency of approximately 10 gigahertz and on for approximately 10 nanoseconds duration is transmitted through a wave guide. Wave guide discontinuities reflect a portion of the incident pulse, and these reflected signals are detected and compared to the incident pulse relative to time and amplitude differences. The discontinuity point in the wave guide is then directly determined using time domain reflectometry, from the time interval for the signal to reach the discontinuity and for the reflected wave totravel back along the wave guide and be detected. As the intensity of the reflected signal is functionally related to the magnitude of the fault, a display of the reflected signal magnitude, compared to the incident signal magnitude, will indicate the magnitude of the wave guide discontinuity.

Method and apparatus for locating and measuring wave guide discontinuities

This paper presents a new fault location system for multiterminal power transmission lines. The algorithm used by this system is suitable for inclusion in a numerical protection relay, which communicates with remote relay(s) over a protective relaying channel. The data volume communicated between relays is sufficiently small to be easily transmitted using a digital protection channel. The new algorithm does not require data alignment, pre-fault load flow information, phase selection information, and does not perform iterations to calculate the distance to the fault. Pre-fault load flow, zero-sequence mutual coupling, fault resistance, power system nonhomogeneity, and current infeeds from other line terminals or tapped loads do not affect the fault location accuracy.

New multi-ended fault location design for two- or three-terminal lines

An accurate fault location algorithm using synchronized sampling

In this paper, a new two-terminal traveling-wave-based fault-location algorithm is proposed. Its main advantage over similar two-terminal algorithms lies in the fact it does not require the data from both line terminals to be synchronized. In order to do so, the algorithm is applied in real time, and a communication system is used, whose data-transmission latency is taken into account in the proposed formulation. The fault locator routines were implemented using the real-time digital simulator (RTDS), such that a wide variety of fault scenarios in a 230-kV transmission line 200 km long was evaluated in real time, considering communication systems with different latency variability levels. The obtained results indicate the proposed algorithm is able to locate faults using either synchronized or unsynchronized two-terminal data, whereas classical methods work properly for synchronized measurements only.

Real-Time Traveling-Wave-Based Fault Location Using Two-Terminal Unsynchronized Data

In this paper, we review the state of the art in the detection, location, and diagnosis of faults in electrical wiring interconnection systems (EWIS) including in the electric power grid and vehicles and machines. Most electrical test methods rely on measurements of either currents and voltages or on high frequency reflections from impedance discontinuities. Of these high frequency test methods, we review phasor, travelling wave and reflectometry methods. The reflectometry methods summarized include time domain reflectometry (TDR), sequence time domain reflectometry (STDR), spread spectrum time domain reflectometry (SSTDR), orthogonal multi-tone reflectometry (OMTDR), noise domain reflectometry (NDR), chaos time domain reflectometry (CTDR), binary time domain reflectometry (BTDR), frequency domain reflectometry (FDR), multicarrier reflectometry (MCR), and time-frequency domain reflectometry (TFDR). All of these reflectometry methods result in complex data sets (reflectometry signatures) that are the result of reflections in the time/frequency/spatial domains. Automated analysis techniques are needed to detect, locate, and diagnose the fault including genetic algorithm (GA), neural networks (NN), particle swarm optimization, teaching–learning-based optimization, backtracking search optimization, inverse scattering, and iterative approaches. We summarize several of these methods including electromagnetic time-reversal (TR) and the matched-pulse (MP) approach. We also discuss the issue of soft faults (small impedance changes) and methods to augment their signatures, and the challenges of branched networks. We also suggest directions for future research and development.

T. W. Stringfield

Papers

Fault Location Methods for Overhead Lines