Earth faults and related disturbances in distribution networks (original) (raw)
Related papers
„Locating Earth-Faults in Compensated Distribution Networks by means of Fault Indicators “
This paper presents theory on transients generated during the initiation of earth-faults. The transients are used for detection and location of faults by means of fault-indicators. Electric and magnetic field measured by the indicator is shown to be a scalar/vectorial sum as a function of line configuration and heights above ground. A field-test in a 22kV rural network is performed in order to investigate coherence with theory, by measuring phase voltages and currents together with the fault-current. A model of the network is established and also a model for the calculation of the electromagnetic field in the position of the indicator is presented.
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.
Detection of high resistance earth faults in medium voltage networks using higher harmonics
2017 18th International Scientific Conference on Electric Power Engineering (EPE), 2017
The paper presents a method for detecting non-linear high resistance earth faults in compensated medium voltage networks, based on the criterion of reactive power of higher harmonics of zero sequence current and voltage. Harmonics content of currents and voltages as the function of network parameters and nonlinear fault resistance was estimated. The model of earth fault protection using that criterion was described. Detection examples of low and very high-resistance earth-faults were attached.
Digital Simulation of Fault Arcs in Medium-Voltage Distribution Networks
2005
This paper deals with the digital simulation of the fault arc in air in a 10-kV medium-voltage distribu- tion network with earth fault compensation via arc sup- pression coil connected to the neutral point. The arc model enables studies on the interaction of the earth fault arc with the electrical power system. The arc has a damping effect on the earth fault current and on overvoltages caused by the initiation of earth faults. The arc model is validated by a comparison of simulation results with arc tests performed in a high-power test laboratory.
2001
The subject of this thesis is the single phase earth fault in medium voltage distribution networks that are high impedance grounded. Networks are normally radially operated but partially meshed. First, the basic properties of high impedance grounded networks are discussed. Following this, the characteristics of earth faults in distribution networks are determined based on real case recordings. Exploiting these characteristics, new applications for earth fault indication and location are then developed. Preface This work is motivated by the practical and theoretical problems studied in several research projects carried out at VTT Energy, and in two technology programmes EDISON and TESLA, during the period 1994-2000. The work has been supervised by Professor Matti Lehtonen from the Power Systems Laboratory in the Helsinki University of Technology. He has also been the manager of our research group, Electric Energy and IT at VTT Energy, and the leader of the technology programmes EDISON and TESLA. I am deeply grateful to him for the research management, advice, cooperation and support during the academic process. For practical arrangements and help in organising the field tests and measurements I wish to thank Mr. Veikko Lehesvuo, Mr. Tapio Hakola and Mr. Erkki Antila of ABB Substation Automation Oy. I am also grateful to the distribution companies, who offered the possibility for field tests and measurements in their networks. I am especially indebted to Mr.
Abnormal Ground Fault Overvoltages in MV Networks: Analyses and Experimental Tests
ENEL DISTRIBUZIONE mainly operates it's MV distribution networks with compensated neutral, obtaining an excellent improvement of quality of supply without any problem for the fault selection. Instead, in many other European countries where ENEL is present, different ways of neutral grounding are used, in particular earthing resistances, assuming that this solution would allow an easier selection of the faulty line (phase to earth fault selection) and a reduction of possible Temporary Overvoltages (TOV), especially on mainly cable network The paper investigate TOV affecting the healthy phases of a radial MV distribution networks operated with noneffectively grounded neutral originated by a single phaseto-ground fault. Theoretical analysis carried out for several network configurations and fault parameters proved that worst-case TOVs can reach 3.5 p.u. phase-toground with ungrounded neutral and 1.8 p.u. with compensated neutral (pure reactance or Petersen coil in parallel with a grounding resistance). The theoretical results, obtained by ATP code, have been fully confirmed by a full-size experimental real field tests performed on the ENEL DISTRIBUZIONE network, both with insulated neutral, stand-alone Petersen coil and Petersen coil with permanent parallel resistance. The study confirms that extended radial MV networks with insulated neutral may experiment 'abnormal' TOVs for certain ground faults, and that neutral compensation has a remarkable effectiveness in suppressing the phenomenon, similar to low earthing resistors, in addition to a drastic reduction of fault currents in earthing plants.
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...
B&H Electrical Engineering
The paper consists of three parts. In the introduction and the first part of this paper are given basic theoretical considerations on possible ways for treatment of the neutral point in distribution grids with special reference to the method of neutral grounding of distribution transformers through a low ohmic resistor and a compensation coil. The second part gives the use analysis of a low ohmic resistor and a compensation coil as the future choice of neutral point grounding on the particular distribution grid powered by a substation TS 35/10 kV. In the third part of the paper, the results were obtained using an adequate dynamic distribution model, using the EMTP-ATP software package. Also, in this part, calculations are made for neutral grounding through a low ohmic resistor, a compensation coil, as well as in the case of isolated grids, and a comparison of the obtained values of the overvoltage coefficients.
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.
Incorporating earth fault location in management‐control scheme for distribution networks
Iet Generation Transmission & Distribution, 2016
This study integrates earth fault location computation with fault management-control schemes for distribution networks. To realise this target, a panel substation is located at the lateral outlet. The faulted section is identified precisely via a fault-location algorithm. Then, isolating the faulted section is accomplished through control signals between the lateral-panel substation and the faulted section isolators. The service restoration is achieved by a direct communication between the lateral-panel substation and the feeder primary substation. The proposed fault-location algorithm is based on the pure fault circuit with the initial condition of the earth fault using the measurements at each lateral panel. For phase-to-ground fault, the initial condition is the series connection for the sequence networks from the fault point. For phase-to-phase-to-ground fault, the initial condition is that the summation of the sequence currents at the fault point is equal to zero. The proposed fault-location algorithm is, therefore, suitable for equipping distribution systems with distributed generation. Moreover, it is applicable for earthed or unearthed networks with all possibilities of transformer connection and load taps. For investigation purposes, simulation tests are performed using the IEEE 33-bus automated feeder example. The simulation test results corroborated the efficacy of the proposed fault management system.