„Locating Earth-Faults in Compensated Distribution Networks by means of Fault Indicators “ (original) (raw)
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Intermittent Earth Fault Passage Indication in Compensated Distribution Networks
IEEE Access, 2021
An intermittent or restriking earth fault is a special type of earth fault that is common mostly in compensated cable networks. A great deal of effort has gone into protection against this type of fault. However, locating this fault has not received much attention. Therefore, there is a need to have a reliable method for locating this fault to repair the damaged cable. In this paper, the principles of a new method developed for locating transient intermittent earth faults on distribution networks are presented. The proposed method employs negative and zero sequence currents, and no voltage measurement is required, which means the proposed method has the potential to reduce cost when implemented in practice. It is intended mainly for typical intermittent earth faults in cable distribution networks where the typical fault resistance is in the range of a few ohms. Real data obtained from practical field tests is used to explain the phenomenon. A series of disturbance recordings obtained from field tests validate the proposed method. INDEX TERMS Fault passage indication, intermittent earth fault, symmetrical sequence currents.
Earth faults and related disturbances in distribution networks
IEE Proceedings - Generation, Transmission and Distribution, 2002
The characteristics of the earth faults and related disturbances, recorded in medium voltage overhead distribution networks during the years 1998-1999 are described. Altogether 316 real cases were analysed. The use of subharmonic oscillation and harmonic distortion was investigated, as a means of anticipating faults. Arcing faults made up at least half of all the disturbances, and were especially predominant in the unearthed network. Fault resistances reached their minimum values near the beginning of the disturbances. The maximum currents that allowed for autoextinction in the unearthed network were comparatively small.
— Speedy detection of faulty cable line with single-phase earth fault (SPEF) and SPEF location in the cable line is extremely important for the speedy elimination of damage and restoration of normal operation of the power supply. Up to now there is no effective method for distant SPEF location in medium voltage cable lines under operating voltage. The electrical quantities of the transition process that occurs during the breakdown of the insulation can be used for solving the problem of single-phase faults location including self-clearing ones. The best opportunity of studying the electromagnetic transients at SPEF in medium-voltage networks and identifying the information parameters, which can be used for distant SPEF location, is a combination of analytical methods on the basis of simplified models of the electrical networks and the method of computer simulation. It is shown that the most efficient algorithm for solving the problem of SPEF location can be obtained by measuring the transient voltage of the faulty phase and the derivative di0(t)/dt at time moments corresponding to i0(t) crossing the zero value. Keywords—medium-voltage cable distribution lines, online fault location, information parameters of electrical variables of transition process, single-phase earth fault location, computer simulation of transient process
— Rapid fault determination of single-phase earth fault (SPEF) and SPEF location on the line are extremely important for the speedy elimination of damage and restoring normal operation of the power supply. Effective methods of SPEF determination on the cable lines under voltage do not still exist in medium voltage networks. The electrical values of the transition process that occurs during the breakdown of the insulation can be used for solving the problem of determining the place of single-phase including self-eliminating faults. The best method to study the electromagnetic transients at SPEF in medium-voltage networks and to identify the information parameters, which can be used for distant SPEF determination, is a combination of analytical methods on the basis of simplified models of the electrical networks and the method of computer simulation. Keywords— power distribution networks of medium voltage, determination of the single-phase earth fault place, computer simulation.
Earth fault location determination independent of fault impedance for distribution networks
International Transactions on Electrical Energy Systems, 2016
This article introduces a new earth fault location algorithm for both single and parallel feeders in distribution networks with single end measurements. The proposed algorithm depends on using the equality between the computed sequence components of the current at the fault point. The algorithm is independent of the dynamic arcing or static fault impedances. Then the faulted network can be decomposed into a prefault network and a pure fault network. The different types of connections of load transformer are considered in the study. This is because of their known influence on the direction of earth fault current in the faulty network. Moreover, the existence of distributed generation is considered during formulating the mathematical core of the proposed algorithm. Hence, the sequence current components at the faulty point can be derived without the need to measure the distributed generation current contribution or its terminal voltage with all varieties of load transformer connection. The proposed algorithm is tested via simulating a real 11 kV cascaded parallel-radial earthed distribution feeder from the Egyptian distribution network using Matlab. Different test cases are examined to visualize the performance of the proposed algorithm with a variety of fault conditions, including the fault impedance, loading, load transformer connection, and existence of distributed generations. All applied simulation tests ensure the efficacy of the proposed algorithm for estimating the fault distance in distribution systems with considerable distributed generation insertion and considering all possibilities of load transformer connection.
Method for detection and location of very high resistive earth faults
European Transactions on Electrical Power, 1999
A new method is presented for the detection and location of high resistive, permanent single‐phase earth faults in medium‐voltage (MV) distribution networks (20 kV). The systems considered are with unearthed or a compensated neutral and the fault resistances covered are in the range of 5 kΩ … 160 kΩ. The algorithms of the new method are based on the change of the neutral voltage and zero‐sequence currents, measured at the MV substation and also at the distribution line locations.
2015
The main aim of the contribution is verification of designed principle for earth fault location in real distribution network which is based on evaluation of voltage sags recorded on secondary side of distribution transformers MV/LV. For this purpose, series of experimental measurement in real compensated MV distribution network were carried out. During the experiments, different types of earth fault (solid, arcing and impedance earth fault) were artificially ignited and all important waveforms (secondary voltages of distribution transformer, fault currents, voltages and currents at supply substation) were recorded for further analyses. These fault records were used for verification of described method. The result of the analyses is answer to question, if it is possible to use the idea of earth fault localization method in real conditions of compensated distribution network operation. INTRODUCTION The requirement to monitor the characteristic parameters of electrical energy and the e...
Identification of ground faults according to the analysis of electromagnetic fields of MV lines
IET Conference Publications, 2009
The methods of assessing the place of the ground fault in compensated MV networks are known. At present realizations, the evaluation of ground faults is usually based on using more methods specialized for the detection of individual types of ground faults. The methods used in the paper follow from the analysis of electromagnetic fields of phase conductors and lines. Ground fault indicators have been installed at points with telecontrolled section switches and reclosers. The development of communication technologies enables new system-wide solutions to be applied in this field. A system-wide solution with telecommunicating indicators and with transmitting not only the result of evaluation but also the development of quantities being measured leads not only to increasing the reliability of determining the section of a MV line affected by the ground fault but, at the same time, it is also possible to assess the type of the ground fault including the prediction of the origination of subsequent ground faults, with the possibility of reducing the number of short-circuits to ground. The used solution enables us to telemeasure the values of phase currents at the point where the indicators have been installed.
Earth Fault Distance Computation Methods Based on Transients in Power Distribution Systems
2014
The most common fault type in MV distribution network is single line to earth fault. The initial transients of earth faults are important especially for unearthed and compensated neutral networks. The earth fault transient signals consist of many different frequency components, which result from charging and discharging of the network capacitances. The transient components provide valuable information for fault location purposes. The charging component has higher amplitude and lower frequency than the discharge component and hence is more suitable to be used for fault location purposes. In this thesis, we discuss algorithms to locate an earth fault in unearthed or a compensated neutral MV networks using the information of the measured transient signal. The networks considered are assumed to be radially operated and they are modeled using Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP). Five types of fault location algorithms have been developed which are called general model (GM) algorithm, exact model (EM) algorithm, continuous wavelet transform (CWT) based method, multiple regression analysis (MRA) based method and artificial neural network (ANN). GM algorithm is developed based on a simplified model of symmetrical components while EM algorithm is developed with exact "pi"-model of symmetrical components. Both algorithms utilize the frequency of charging transient to estimate the fault distance. CWT based algorithm requires both voltage and current of transient signals to estimate the fault path inductance. MRA and NN algorithms were developed using the transient signal measured from the secondary side of the MV/LV distribution transformer. In addition, an algorithm to find a correct path towards the position of fault in network which has many branches is presented. The results from intensive simulations and experiments in actual distribution networks are also presented in this thesis. The results are analyzed using signal processing techniques. The algorithms apply continuous wavelet transform (CWT) to locate the dominant charge transient frequency and extract the specific coefficient corresponding to the charge transient frequency. In this thesis, the properties of Hilbert transformation (HT) are used to estimate the damping attenuation of the transient signal. Finally the performance of the proposed fault location algorithms is evaluated and the results are compared. Based on the simulation results, it is found that the proposed algorithms work at a reasonable level of accuracy. The results from real experiment data show that both CWT and GM algorithms have a comparable result.
Energies
This paper presents the final development of an expert system utilizing a measurement of cable screen earthing transient current. The developed system allows for identification and location of earth fault in underground cable and mixed lines (underground cable and overhead line) and monitoring of an earthing system and cable screen connections. The unique feature of the developed earth fault locating system is the possibility of identification of line type and branch of the MV underground cable or mixed feeder under earth fault conditions. As a result, the time to remove failure can be greatly reduced and the number of earth fault indicators installed in the distribution network can also be reduced. Unfortunately, in order to operate properly, the previously developed system requires a fundamental—50 Hz component of the measured zero-sequence cable core current and cable screen earthing current; therefore, short transient earth faults without steady-state earth fault currents cannot...