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Highlights • A new fault location method using TT-transform and SVM is developed with high accuracy under wide variations in fault conditions. • SVM classifiers determine whether the fault occurs in the first or second half of the underground cable or overhead line. • To increase the classification accuracy, SVM parameters are tuned using PSO. • After faulty half identification, Bewley's lattice diagram and the transformed voltage signal is used for locating faults. • A comparison is made with the methods in the literature in terms of the fault location accuracy. Abstract This paper proposes a hybrid fault location technique in an overhead line that contains an underground cable. Time-time (TT)- and S-transforms are used to extract information from the transient voltage signals measured at a single end. This information is used to train a support vector machine (SVM) which determines whether the fault occurs in the first or second half of the underground cable or overhead line. To enhance the classification accuracy, the SVM parameters are optimized using the particle swarm optimization (PSO). After the identification, the fault is located using Bewley's lattice diagram and the transformed voltage signal. The performance of the proposed method is assessed under various parameters such as fault type, resistance, inception angle, and location. Simulation results validate the high accuracy of the proposed method in identifying the faulty section and locating the fault. Also, it is shown that the proposed technique outperforms other methods in the literature. [ABSTRACT FROM AUTHOR]

There is a growing concern regarding a more accurate assessment of the transient behavior of overhead lines and underground cables. Traditionally, displacement currents are neglected in the evaluation of the ground return correction terms, thus only the transmission line impedance being affected. However, if these currents are to be considered, the ground cannot be assumed as an equipotential and there are some ambiguities depending on the definition used to determine the conductors’ voltages. Furthermore, given the numerical challenges associated with the infinite integrals needed to obtain the ground return parameters, it is rather common to use closed-form approximations instead. In this paper, we assess the influence that the different formulations may have in modelling two distinct overhead lines. Both frequency and time-domain results are presented and discussed. The results indicated that there are some mismatches between induced voltages calculated using the voltage formulation with quasi-TEM approximation and those using the potential formulation with closed-form approximations. [ABSTRACT FROM AUTHOR]

Typically, in cable system modeling for power system transients studies, the ground return effect is taken into account in the per unit length impedance, its effect on the admittance being neglected. In this paper, the per unit length impedance and admittance matrices for a cable system are established, based on the approach previously presented by the authors for the case of a single insulated cable in a dispersive medium. The presented formulation is derived from a full-wave approach, assuming quasi-TEM propagation which was proved suitable for the frequency range of interest. A comparison of the propagation modes indicates that the inclusion of the ground return admittance affects significantly the ground and intersheath modes in the high frequency range, i.e., above a few kilohertz. Test cases where the different modes are excited are used to analyze the impact of including the ground return admittance in computing the transient response of underground cable systems. The results indicate that this impact increases for high resistivity soils and shorter cables. [ABSTRACT FROM PUBLISHER]

Underground cables are intensively used, especially for transporting energy in urban areas. In general, the currents flowing in the cables change, following the loads profile. Moreover, the optimal installation of these cables must consider geometry, magnetic fields and arrangement costs. This paper proposes and analyses different statistical calculations of these optimal locations. The application of the methods to real data demonstrates the effectiveness of the statistical approaches in terms of costs and magnetic fields. [ABSTRACT FROM AUTHOR]

This paper introduces the finite element method is used for predicting the temperature distribution in underground cable, using arch-shaped finite elements with explicitly derived solution matrices. A general derivation of the finite element equations by the method of weighted residuals (Galerkin’s method) is introduced. The arch-shaped finite elements are very suitable for cable geometries, and the explicit nature of the solution matrices allows for optimal computer usage. A 18-element two-dimensional slice of core conductor (single) bounded by two 90 °C inclined planes divided into arc shaped elements, are used for solution to a transient heating problem, and this defines the scope of this technique. The model is applied to one 3-core underground cables of 6.6 kV. [ABSTRACT FROM AUTHOR]

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Underground electrical substations play an increasingly significant role in urban economic development for the power supply of subways. However, in recent years, there have been few studies on the seismic performance of underground electrical substations involving the interaction of soil--structure--equipment. To conduct the study, three-dimensional finite element models of an underground substation are established. The implicit dynamic numerical simulation analysis is performed by changing earthquake input motions, soil characteristics, electrical equipment type and structure depths. According to a seismic response analysis, acceleration amplification coefficients, displacements, stresses and internal forces are obtained and analyzed. It is found that (1) as a boundary condition of soil--structure, the coupling boundary is feasible in the seismic response of an underground substation; (2) the seismic response of an underground substation is sensitive to burial depth and elastic modulus; (3) the oblique incidence of input motion has a slight influence on the horizontal seismic response, but has a significant impact on the vertical seismic response; and (4) the bottom of the side wall is the seismic weak part of an underground substation, so it is necessary to increase the stiffness of this area. [ABSTRACT FROM AUTHOR]

To test theoretical methods proposed or adopted by researchers for the assessment of lightning-induced currents on buried cables, three sets of experimental data available in the literature are frequently used. The published tests results consist of the comparison of computed currents with the measured ones (of each set). For one set, a reasonably good agreement has been obtained by the assumption of a finitely conducting homogeneous ground (one-layer soil model). Recently, a reasonably good agreement has been obtained for the second set of data by more accurate modeling of the soil using a two-layer soil model. While for the third set, an important disagreement is still observed. In this paper, we propose an analysis which allows inspecting possible reasons of the latterly observed disagreement. It is shown that, the average accuracy of the calculated currents for a one-layer soil model can be improved from 6 to 15 % by the assumption of a two-layer soil model. Furthermore, the average accuracy obtained for a two-layer soil model can be improved from 0.3 to 51 % by the assumption of a three-layer soil model and for which the waveshapes of the measured and calculated currents are in a reasonably good agreement. [ABSTRACT FROM AUTHOR]

The analysis of the thermal stress of underground MV power cable joints under different environmental conditions, both in normal operation and during faults, is crucial to assess any correlation between the occurrence of overheatings and the anomalous increase of failures (two to three times compared to previous years) which have been observed in the Italian distribution network during summer 2015 (the hottest year ever since 1880). In order to perform this analysis, we have developed a nonlinear circuit model that is able to estimate, both in stationary conditions and in transient ones, temperature profiles inside MV joints, referring to different environmental conditions and with current flowing both in the core conductor and in the metallic shield. The model has been implemented in the Simulink environment and then it has been validated with a set of experimental tests, specifically set up in order to check its performance in steady state and during transients. The numerical results were always in good agreement with the measurements. Subsequently, the circuit model has been employed to perform a predictive analysis of the joint internal temperatures, which may be achieved in operation and during faults by varying the ambient temperature. In all cases, the temperature limits tolerated by insulations have never been exceeded. [ABSTRACT FROM AUTHOR]

This paper presents a model of a HV (High Voltage) three shielded single-core cables installed in a trefoil configuration and solid-bonding grounding. This model is based on the distributed parameters theory. It is applied to the connection between the 150 kV substations of Tyna, Taparoura and Sidimansour, three urban zones located in Sfax a coastal city of Tunisia. The resulting model is implemented in a computer code in the Matlab environment. To validate this model, it is represented by block diagram in the Simulink-SimPowerSystems environment where the cable is modeled by several sections Pi. Studying the two situations (no-load test and load test), the proposed model is validated in normal state by comparing the results obtained numerically (by the computer code and block diagram) along the cable and with some recoded real measurements available in sending-end (Tyna substation). The results comparison shows a good agreement and confirms the exactness and the robustness of the proposed model. Finally, some insulation default cases are modeled and analyzed. [ABSTRACT FROM AUTHOR]

The paper is aimed to analyse the influence of the degradation, in the course of time, of pipelines insulating coating in the frame of power frequency electromagnetic interference generated by power lines on buried metallic pipelines. To our knowledge, such an issue is generally not considered when evaluating induced voltage and current along the pipe-earth circuit; on the contrary, such a phenomenon should be taken into account because under certain conditions, the level of the electromagnetic interference can significantly vary during the pipeline life (some tens of years). In the paper, we propose an empirical law to describe the degradation in the course of time of the pipe insulation resistance to soil, and we show, by means of simple examples of interference calculation, why such a degradation should be taken into account. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The possible placements of energy storages in the power supply system of underground were considered. The advantages and disadvantages of each placement of the energy storages according to various indicators were defined. According to the results of the general analysis of existing researches, their comparative analysis and the proposed approach using a scoring scale was established, the placement of accumulators on underground rolling stock was the most appropriate. [ABSTRACT FROM AUTHOR]

This paper investigates the efficiency and accuracy of the best L1 piecewise monotonic data approximation (best L1PMA) in order either to approximate the transfer functions of distribution BPL networks or to reveal the aforementioned transfer functions when various faults occur during their determination. The contribution of this paper is quadruple. First, based on the inherent piecewise monotonicity of distribution BPL transfer functions, a piecewise monotonic data approximation is first applied in BPL networks; best L1PMA is outlined and applied during the determination of distribution BPL transfer functions. Second, suitable performance metrics such as the percent error sum (PES) and fault PES are reported and applied so as to assess the efficiency and accuracy of the best L1PMA during the determination of distribution BPL transfer functions. Third, the factors of distribution BPL networks that influence the performance of best L1PMA are identified. Fourth, the accuracy of the best L1PMA is assessed with respect to its inherent properties, namely, the assumed number of monotonic sections and the nature of faults, that is, faults that follow either continuous uniform distribution (CUD) or normal distribution (ND), during the determination of distribution BPL transfer functions. Finally, best L1PMA may operate as the necessary intermediate antifault method for the theoretical and practical transfer function determination of distribution BPL networks. [ABSTRACT FROM AUTHOR]

Lighting systems are usually one of the largest electrical end-uses in underground metro stations. Taking into account that budget restrictions in publicly owned companies hinder energy efficiency retrofit projects that require high initial investments, affordable energy saving strategies are needed. This paper presents a low-cost approach for reducing lighting electricity use in underground stations, without affecting passengers’ comfort or the metro operator’s service. For this purpose, an adaptive lighting strategy of dimming the illuminance levels of artificial light sources has been developed. Dimming controls are based on the occupancy of the station, and the preventive maintenance and cleaning cycles of the luminaires. The stations’ monthly occupancy patterns are defined through the k-means clustering technique. To illustrate its effectiveness, the method was applied to 115 underground stations of the Barcelona metro network. The results revealed overall electricity savings of 255.47 MW h on a biannual basis, which represents 36.22% of the stations’ baseline lighting consumption. Individual energy savings were found to range from 25 to 87.5 MW h/year in the stations of the Barcelona metro network, depending on the number and profile of station users. The research findings will undoubtedly be useful for the future energy efficiency project plans of worldwide metro operators and managers of other underground spaces. [ABSTRACT FROM AUTHOR]

A system of underground distribution cables is usually used to carry electrical energy inside the populated areas. Under loading and faulty conditions backfill soils lose their moisture content around underground distribution cables. This phenomenon forms dry area around the underground cables and leads to the increase of thermal resistance of backfill soil and sequentially decreases in the cable rating. One aim of this study is to determine the most appropriate of the artificial soil that can be used to fill the blanks around the underground distribution cables to minimise the effect of dry zones that cause thermal failure to the cable insulation. The results of the experimental works conducted in this study showed that some soils lose moisture faster than the other; hence in these types of the soil the dry area will be formed around the underground cable faster than the others. [ABSTRACT FROM AUTHOR]

An incipient and self-clearing arcing fault can be utilised as a precursor of an imminent permanent failure for monitoring of underground cables. Due to very short duration of the incipient faults, generally they cannot be detected by conventional protection relays. This study presents a new method for detection of incipient cable failures by using measured current and voltage at one end of the cable. The incipient faults are detected using an innovation signal calculated from the measured fault current via a Kalman filter. Upon change detection by the innovation signal, the change is checked for discriminating possible incipient fault from other similar conditions. The proposed method is evaluated using several simulations and field data collected from a real network. The results confirm that the method can achieve high accuracy and speed for detection of cables incipient faults. [ABSTRACT FROM AUTHOR]

In order to prevent unexpected electrical outage and to save on repair expenses, an online data-driven prognosis method for monitored underground cable is proposed. The method is nondestructive and nonintrusive. The field data of voltage and current were collected from an underground distribution cable lateral installed in a residential area. Potential useful features were selected based on the data-driven method using the training data. The rationality of selected features was verified in view of cable aging mechanisms; after that, the useful features were finally determined. The remaining life of cable was forecasted by predicting the time for the cumulative effect of the selected features to reach the threshold. The performance of the developed prognosis method was tested and evaluated using the field testing data. The standard deviation of the prognosis results at different arrival times is used as a source of uncertainty estimation (reverse of confidence estimation). The results demonstrate that the method can continually offer valuable remaining life prediction of the monitored underground cable as time goes on. When the predicted fault times approach the actual fault time, the standard deviation value is small. When the standard deviation value is small, there are steady forecast results and usually small residuals. [ABSTRACT FROM PUBLISHER]

High-voltage earthing system design is required to ensure safety compliance and adequate operation of the high-voltage infrastructures. The transmission lines form a solid part of the high-voltage infrastructure. The underground to overhead (UGOH) pole earth grid is one of the main challenges when it comes to transmission line earthing system design. To ensure safety compliance at low cost, counterpoise earthing is used at the UGOH pole for the underground lines. The counterpoise aids in lowering the UGOH pole earth grid resistance. This paper addresses the counterpoise analysis as currently being studied. Furthermore, it introduces the counterpoise mutual voltage between the faulted phase and the counterpoise and its impact at the UGOH pole earth potential rise. Case study is included. [ABSTRACT FROM AUTHOR]

With the proliferation of technologies and underground systems, analysis of thermal fields in soil has become a topic of great interest in the developing technology of buried structures. In this work, we have investigated the steady-state temperature field (from linear heat sources – buried cable) in a different type of soil and excavation geometry. In a laboratory, a physical model was built on scale, which reproduces an "undisturbed" area containing a linear thermal source. This scale model was produced for experimental activity. A measuring chain was made to analyze the thermal field in various types of soils, by varying the electrical current through the line source. The physical model was recreated using a finite volume calculation software. Analysis of the different field system configurations were completed and we have studied a model for the improvement of the design method. [ABSTRACT FROM AUTHOR]

The problem considered is a vertical electrically small wire antenna located underground, which transmits electromagnetic signals to the ground. Getting Green’s function of the vertical dipole underground was the first step to calculate this issue. A quasistatic situation was considered to make an approximation on Sommerfeld integral for easy solution. The method of moments was used to solve the current distribution on the antenna surface at different frequencies, which laid a good foundation for obtaining the electric field of the antenna. Then the axial and radial components of the electric field with the radial distance on the ground were investigated, as well as the voltage received on the ground. Furthermore, the influence of the frequency and stratum parameters on current and electric field was studied to understand the variation clearly. [ABSTRACT FROM AUTHOR]

In this paper, a novel technique based on magnetic field sensing is proposed for underground power cable detection and inspection. In this technique, the current sources of the underground power cables are reconstructed based on a set of measured magnetic field values at the ground surface level emanated by the electric currents carried by the underground power cables. The stochastic optimization technique developed with an artificial immune system algorithm is applied to realize the reconstruction. The principle of this method was proved and verified experimentally by our laboratory setup. Application of this method was demonstrated on the simulation models of 11- and 132-kV underground power cables. The reconstruction results of the electrical and spatial parameters of the cables match accurately with the actual source parameters of the cables in the models. This paper shows that the proposed method is able to remotely detect the horizontal locations and vertical depths of underground power cables with high accuracy at the ground surface level requiring no prior knowledge about the exact locations of the cables. Thus, it can be potentially used to develop a portable locator for providing a map of the underground electrical cables by simultaneous detection of multiple power lines. This method can also enable engineers to correctly inspect the operation states of the target cables during onsite maintenance. This technique is applicable to various laying conditions and cable configurations (three core or single core) of the underground power cables. In addition, this is an entirely passive method and does not need any signal injection into the cables. [ABSTRACT FROM PUBLISHER]

The popularity of underground cables to replace overhead lines is increasing. This is partly a consequence of the requirement for better reliability and supply security. In some countries, the authorities have set maximum interruption durations for distribution system operators to steer the operators to avoid the use of overhead lines. However, although faults are typically of a rare occurrence in underground cable networks, they cannot be completely avoided. Since the fault repair process in an underground cable network is time consuming, the distribution network should be meshed, and the rate of disconnecting switches should be high enough. However, this is not always possible or economically feasible and, therefore, other opportunities to restore the electricity supply should also be considered. This is especially the case for branch lines without a backup option. Yet, the power should be restored in a reasonable amount of time, which emphasizes the significance of an appropriate switch placement strategy and reserve power planning. This paper proposes a methodology to analyze the costs of different reserve power strategies and to optimize the reserve power arrangements. The reserve power strategies under consideration are the application of reserve power cables and reserve power generators and looping of the existing branch lines. [ABSTRACT FROM PUBLISHER]

This paper proposes a hybrid firefly algorithm (HFA) to assist in decision-making for reactor arrangement in underground cable transmission systems. The HFA method is proposed based on the analysis of phototaxis behavior of fireflies, and enables solving the optimization problem effectively. In this study, by formulating high relationships among connected reactors, sheath loss, and induced voltage, the HFA method is employed to determine the appropriate reactor placement in an underground transmission systems. Through the tests made on different transmission lines along with the results compared to other methods, the proposed approach provides satisfactory decision support for reactor placement and serves as a beneficial reference for underground transmission planning and design. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the influence of construction-based and grounding system parameters of underground power cables 6-10 kV on magnetic flux density levels. It is shown that grounding a system at its start or end point without grounding it at the ends is the worst in terms of the magnetic field levels due to the absence of induced current in a shield. Therefore, it is possible to decrease magnetic field levels above cables by increasing the currents in a shield by grounding cables at the ends and by varying the cable parameters, such as the distance between phases and a cross-section of the shield. [ABSTRACT FROM AUTHOR]

This paper addresses the capacitor bank switching back to back to underground cables. The high currents recorded during the capacitor bank switching occur due to the traveling waves in the underground cables. The detailed analytical study of the capacitive inrush currents is done. The closed-form expressions of the inrush current waveforms due to the initial current surges as well as due to the superposition of the initial and reflected current waves are derived. The formulas for the peak inrush current and its maximum rate of rise are obtained. The case study of the 24-kV capacitor bank switching back to back to the underground cables is described. The results of the field measurements are compared with the results of Electromagnetic Transients Program simulation. The dependence of the inrush current peak on the number of the cables, and the equivalent inductance between the capacitor bank and the substation busbar as well as on the cable length are analyzed. The inrush currents caused failures of the capacitor bank circuit breakers. Since the described capacitor inrush current significantly exceeds the “inrush current of the isolated capacitor bank,” the selection of the capacitor bank switchgear should be taken into account. [ABSTRACT FROM PUBLISHER]

Present trend of laying cables for various purposes is to lay underground. Companies prefer laying the cables underground because the climatic adversities don't affect this. With advantages come challenges. There are many difficulties in laying the cables and once laid in case of any complaints, it is difficult and costly to fix it. This paper is about the robot that is designed by us which is capable of finding where the complaint lies, so the engineer can directly get the hole dug at that point and fix the issue. The basic principle of Electromagnetic Theory is employed to detect the discontinuity in the cable. Using a signal injector, a low frequency signal is passed through the wire and the induced magnetic field is used to detect the fault. [ABSTRACT FROM AUTHOR]

Purpose. To substantiate the possibility of 35 kV voltage application in deep-level ore and coal mine power supply systems to supply underground electric collectors and draw up the principles of ensuring their operational safety. Methodology. We have used theoretical and experimental methods, in particular, probability theory and analytical research methods to estimate electrical elements reliability and power supply electric safety; general electrical circuit theory to estimate emergency processes. Findings. By selection of appropriate level of voltage we can solve the deep mines power supply problem comprehensively and for extended period of time taking into account growing electrical loads in underground electric collectors. This way of improving the efficiency of deep-level energy-intensive mines supply appears the most realistic and technically feasible. To reconstruct the power supply system we can supply 35 kV voltage to the depth over 1000 m to the 35/6 kV underground substation and distribute power at deeper horizons with voltage of 6 kV. Between different schemes of power supply for the 35/6 kV underground substation the most preferable is the scheme 'block line - transformer' allowing to refuse the 35/6 kV distribution device and meet existing general and specialized requirements of maintenance and safety. We have presented theoretical substantiation of the selective method of automatic and continuous monitoring of 35/6 kV electrical grid isolation parameters. This method is based on impinging of operational bi-frequency sinusoid signals of nonindustrial frequency on electrical grid, and on the principle of faulted phase earth protection during ground faults in 6-35 kV electric grids for the purposes of improving the electrical safety. Originality. Alternative method of improvement of the power supply effectiveness in deep geological position is presented. We have shown that change-over to a higher voltage class of mine supply networks is a promising method. To ensure the safety, we propose the method of automatic, continuous and selective monitoring of isolation parameters relative to ground without removing the operating voltage. Practical value. Improvement of the effectiveness of power supply in deep geological position can be performed through power quality enhancement and reducing the energy loss. [ABSTRACT FROM AUTHOR]

Icing of overhead ground wires on transmission lines may result in faults and widespread power outages. This paper investigates the feasibility of an unconventional overhead line structure that is equipped with underground rather than overhead ground wires to prevent faults caused by icing. The underground ground wire is a buried bare conductor connected to the grounding of each transmission-line tower. To analyze the ground fault of the overhead line structure, this paper derives analytical equations to evaluate the current and potential distribution in the underground ground wire, earth surface potential around the wire, and grounding impedance of the faulted tower. The validity of the presented equations is verified by measurements. Based on the ground fault analysis, this paper evaluates the electrical safety of the discussed overhead line structure. Lightning shielding of overhead lines is not considered in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Differential protection scheme is based on comparison of measured variables such as current and voltage at the two ends of a line via a communication channel such as pilot wire. This scheme is preferred and extensively used in distribution feeder protection system in Malaysia due to its fast operation. However pilot-wire differential scheme has its own drawbacks especially on the maintenance of the pilot-wire. Once the plot-wire is out of service, the feeder protection is jeopardised. One of the options to overcome such maintenance issue is to adopt directional relay as the feeder protection. This paper investigates a suitable relay connection and the maximum torque angle for the directional relay for 33kV underground network. In this study, a section of 33kV underground network in Kuala Lumpur (KL) city has been analysed. All faults types have been simulated at all possible location in the network. The obtained voltage and current were then used to determine the operation of directional overcurrent and earth-fault relay. The simulation results indicate that 30° relay connection with 0° maximum torque angle (30°/0°) is the most suitable setting to be applied for 33kV underground network in KL, as against the best general and most versatile setting, 45°/90°. [Copyright &y& Elsevier]

Abstract: In this paper a comparison among different shielding techniques for the junction zone of high voltage underground power lines is presented. Three technologies are taken into account: flat conductive shield, passive loop and High Magnetic Coupling Passive Loop. The three solutions are simulated using 2D and 3D models in order to evaluate the magnetic flux density at ground level, the shielding factor and the effectiveness of connection between components of the shield. Shielding performances and installation requirements have been compared by highlighting advantages and drawbacks of the three systems and identifying the most suitable solution with reference to the Italian regulatory framework. [Copyright &y& Elsevier]

In this study, design of a physical underground cable model provided by a cascade connection of lumped- parameter equivalent ¶ (pi) circuits for laboratory scale power system applications is presented. The validity of the model was confirmed by a power transmission system using an infinite bus bar constituted of a static synchronous compensator (STATCOM) and the physical cable model. STATCOM exhibits the structure of a three-phase, twelve-pulse voltage source converter that operates on the principle of microcontroller based reactive power control. In such type of a power system, the effects of powering an unloaded and loaded transmission line, as well as load shedding on the cable line were investigated through various experiments and simulation studies. The simulation models for the power and control systems were built by employing the PSCAD/EMTDC program's C-programming interface and the graphics based models in its model library. The experimental results are compared with the results obtained from the PSCAD/EMTDC simulation program. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an analysis of closed-form expressions for ground return impedance of overhead lines and underground cables. For the former an actual solution to Carson’s infinite integral is obtained via integral transformation techniques while for the latter an approximate expression based upon asymptotic expansion is presented. Numerical integration based upon Gauss-quadrature is performed for the comparison. Several test cases are presented considering different values for soil parameters. The results indicate that good accuracy was obtained. Limitations of the proposed expressions are also presented. [Copyright &y& Elsevier]

Abstract: Generally, fault location in underground transmission cable system is very difficult because of many noises. Therefore, a method to remove the noise in power cable systems is proposed by applying noise cancellation technique based on the correlation of multiple scales of the transients using wavelet analysis. After the noise cancellation, the transient signals reflected from fault point and other end of cable can be used to locate the fault using single-ended approach when the single line-to-ground fault occurs in underground transmission cables. This paper proposes a fault location algorithm using noise cancellation technique in noisy environment. This algorithm is simple and straightforward. The simulation results of 225 fault conditions including different fault resistance, fault location and fault inception angle and real test results prove it can accurately locate the fault in very noisy situations when the single line-to-ground fault occurs in the system. [Copyright &y& Elsevier]

In this article we propose an efficient and accurate method for fault location in underground distribution systems by means of an Optimum-Path Forest (OPF) classifier. We applied the time domains reflectometry method for signal acquisition, which was further analyzed by OPF and several other well-known pattern recognition techniques. The results indicated that OPF and support vector machines outperformed artificial neural networks and a Bayesian classifier, but OPF was much more efficient than all classifiers for training, and the second fastest for classification. [ABSTRACT FROM PUBLISHER]

The article discusses the construction of New York Subway which began in 1904, with reference to the book "The New York Subway: Its Construction and Equipment," by Rosalind Williams published in the same year. Topics discussed include construction of underground railroads beneath the streets of New York City, buried subsystems of electrical power, water service and telephone lines, and author's experience of reading Cesar Aira's book "An Episode in the Life of a Landscape Painter."

Abstract: This paper outlines the benefits of undergrounding power lines. We present research that reveals the reliability and operation and maintenance (O&M) impacts of electric underground lines relative to overhead lines. This research uses a comprehensive dataset from 163 US electric utilities. Holding the effects of other important operating variables constant, our research indicates that undergrounding reduces O&M cost and enhances reliability by reducing power outage durations. We also provide a brief discussion of other considerations that are important when weighing the benefits and cost of placing power lines underground. [Copyright &y& Elsevier]

Fault point locating systems based on surge current detection have recently been used for fast recovery of underground transmission lines from faults. Electromagnetic induction type sensors have mainly been used for the detection of surge current. However, they are susceptible to electromagnetic noise which causes unstable system operation. To solve this problem, Tokyo Electric Power Co., Toko Electric Corporation, and Fujikura Ltd. jointly developed a new system using optical fiber current sensors. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 21-28, 2012; Published online in Wiley Online Library (). DOI 10.1002/eej.20981 [ABSTRACT FROM AUTHOR]

The fault location in underground cables is characterized as the technical difficulties due to complexities in cables. Based on the direct circuit analysis, a fault location algorithm for underground cables with no laterals is presented in this paper. The single-end phasor measurements, including the voltages and currents sampled in the substation side, are utilized to locate the single phase faults in the typical single-conductor cross-linked polyethylene (XLPE) cables rated at the medium voltage (MV) levels. The distinctive cable characteristics are considered, such as relatively large capacitance, effects of sheaths and sheath bonding methods. The different fault scenarios are taken into account as well. The effect of changes of cable parameters and application of static response load model are also investigated. The simulation studies demonstrate the proposed algorithm can achieve the high accuracy under various system and fault conditions. [ABSTRACT FROM AUTHOR]

This paper analyzes the thermal effects derived from the use of different screen shapes when shielding the magnetic field generated by underground power cables. A parametric analysis is developed to show the influence of the geometrical and the electrical parameters of the shield on the maximum temperature achieved by the power cables in order to analyze the impact of this technique on the ampacity of the line. A 2-D finite element approach is employed in this study to verify the performance of different types of screens (horizontal plate, reverse-U, and H-layout) in terms of shielding efficiency, overheating of the power cables, and operational costs. [ABSTRACT FROM AUTHOR]