Influence of soil conductivity in capacitive coupling between power lines and pipelines

Background: For efficient operation and reliability of power systems, continuous monitoring of power line sag is needed. The dynamic thermal line rating of a power transmission system at any instant may also be evaluated if power line sag information is available at that time. The smart grid also encourages sag measurement technologies so that the operator can take immediate corrective action whenever power line ground clearance exceeds the maximum allowable limit. Aim: The purpose of this paper is to design and implement an overhead conductor altitude measurement system using Global Positioning System technology with accuracy enhancement techniques for sag monitoring in power transmission lines in real time. Method: The observed Global Positioning System (GPS) measurements are found inaccurate by the comparison of observed GPS measurements with physical measurements taken at the field site. Therefore, various combinations of accuracy enhancement techniques such as Bad Data Identification/Modification (BDIM), Least Square Parameter Estimation (LSPE), and Haar Wavelet Transform (HWT) are used. Results: The field test has been conducted successfully on 11 kV power line by using the designed system to measure the altitude of overhead conductor at mid-span as well as at the pole to evaluate conductor sag of power lines in real time. Conclusions: It is found that HWT after LSPE and BDIM combination of accuracy enhancement techniques improves the accuracy of GPS measurements significantly and hence conductor sag can be monitored on-screen directly.

As a way to expand electric capacity in power line with hovering of electric power demand, STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) overhead conductor which cans double ampacity has been developed. The STACIR/AW power line is mechanically composite stranded wire composed of INVAR/AW stranded wire as core for sag control and heat-resistant aluminum alloy for delivering doubled electric current. Recently, in order to ensure stable line operation and to predict its span of life, the changes of thermal properties for STACIR/AW have been investigated. In the present work, the changes of strain with temperature and the creep behavior as important factors in sag control will be presented. The transition temperature of STACIR/AW 410sqmm was estimated approximately 130°C and the creep rates were decreased with temperatures.

Communication is the backbone for all modes of development in this modern world. Without communication the whole world is virtually deaf and dumb. In order to minimise the cost spent on additional wires, we are using the same existing power lines as a medium of communication in this project. The data are mixed with radio frequency carrier (40-500 kHz) and then injected into high voltage power line using a suitable Coupling Capacitor.The power line has a rigid, long conductor parallel to the ground that guides the carrier waves to travel along the transmission line. This system which is economic and reliable for inter grid message transfer is mainly used for telecommunication, tele-protection and tele-monitoring between electrical substations through power lines at high voltages such as 110KV, 220KV, 440KV. I. INTRODUCTION The PLCC has a transmitter block and receiver block. In the transmitter block ,we use audio signal as an input which should be amplified with a pre amplifier before getting modulated. After pre amplification the audio signal is modulated with the carrier signal by FM modulator. Before transmitting the signal, it should be amplified once again using RF amplifier. Now the modulated and amplified signal is given to the transformer in which isolates RF signal with the 230V AC supply. Finally the signal is coupled to the AC line with the help of coupling capacitor, which allows high frequency modulated signal simultaneously providing high impedance to the power frequency (50 Hz). In receiver block the signal is received from the 230V power line through the coupling capacitor. Then the received signal is given to transformer which is used for isolation purpose and then the RF signal is amplified using RF amplifier. The amplified output is given to PLL FM demodulator for the extraction of audio signal from the modulated signal. Then demodulated output is power amplified and is given to the loud speaker. II. COMPONENTS A. I.Ne 555 Timer (Modulator) The NE555 is a highly stable controller capable of producing accurate timing pulses. It is an 8pin timer IC and has mainly two modes of operation: monostable and astable. With monostable operation, IC 555 is commonly used for generating time delays and pulses.In the time-delay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor.The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. This IC consists of 23 transistors, 2 diodes and 16 resistors. The explanation of terminals coming out of the 555 timer IC is as follows. The pin number used in the following discussion refers to the 8-pin DIP and 8-pin metal can packages.The NE555 is characterized for operation from 0°C to 70°C

The paper is dedicated to studying the contribution of underground image of overhead power lines to the actual electric field strength at a certain point of interest in their immediate vicinity. More precisely, it is about the image of an electric charge; accordingly, an analytical method is developed, allowing as the linear charge density to be calculated based on the effective (r. m. s.) phase voltage and also, the calculation of the electrical potential at the surface of the live conductor. The analytical results were the basis for the validation of some simulations performed with CST Studio and EMFACDC for various power line configurations. An application has been developed to study the influence of soil conductivity and permittivity, the results being compared with the (theoretically) extremes: perfectly conductive and perfect insulator cases. The results showed an increase of about 65% of the electric field strength in wet soil, relative to dry soil. This conclusion is an argument that nuances the rather widespread, superficial approach that, from the point of view of the formation and the influence of electrical charge image in the soil, any soil is a perfect conductor. Finally, a number of achievable recommendations are done, aiming on reducing the exposure to electric fields generated by overhead high-voltage power lines (OhHVPLs).

Electromagnetic Field interference (EMI) caused by electric transmission and distribution lines on neighboring metallic utilities such as communication cables, water, gas and oil pipelines became a major concern in Saudi Arabia due to the significant increase in the load, rapid and large power, water desalination and pipelines systems expansion, new discoveries of oil and gas resources, and short-circuits. The mechanisms of electromagnetic field interference between a power system network and a buried pipeline at low frequencies have been traditionally divided into three categories: inductive, conductive and capacitive coupling. Conventionally, the inductive interference is analyzed with a circuit model approach and the conductive interference is determined using appropriate grounding software. The inductive and conductive components are then added together. Cases arise in practice in which long electric power lines and pipelines, sharing the same corridor, follow curved path which intersect one another, diverge, recon verge, etc.., making them difficult to model accurately with a circuit model approach. Recently, field-theory-based software does away with the assumptions and accounts simultaneously for inductive, conductive and capacitive coupling between all the buried and aboveground elements modeled. This paper illustrates practically, what would be the interference effects from AC power lines in mainly metallic pipelines. The determination of interference effects in a typical right-of-way is a complex procedure requiring not only a good knowledge of conductor layout, power line and pipeline electrical characteristics and electrical system parameters, but also an accurate representation of the soil structure resistivity. A complete case study of a 230 KV transmission line EM1 effect on a oil buried pipeline will be presented. The paper outlines why should we observe the safety of people who come in vicinity of such pipelines, and why this EM1 studies are important and should be conducted and checked when ever and expansion is planned?, also, the safety of equipment connected to the pipeline is vely essential to both utilities and industries and it help saving tremendous amount of operation and maintenance (0 & M) costs.

Cardiac muscle is a syncytial tissue of electrically coupled cells in which excitation of one cardiomyocyte spreads to all cardiomyocytes. Mechanisms of cell coupling in myocardial tissue can be categorized in two main groups: mechanisms that connect the intracellular parts of myocytes together (i.e., gap junctions), and mechanisms that act through changes in the small extracellular space of intercalated disks (ICD). The latter mechanisms are electric field coupling, ephaptic coupling, K accumulation, and capacitive coupling (Sperelakis and McConnell, 2002). ICD cleft has a limited space and therefore a small ionic current can change both its electric and diffusion potentials via the change in the ionic concentration. The potassium accumulation, for instance, can change the reversal potential of potassium channels toward more positive values, and as a results of which the potassium current can depolarize the cells. When ionic currents change the electric potential of cleft we have ephaptic or electrical coupling, and when the capacitive current of membrane changes the electric potential we have capacitive coupling. In electrical coupling through gap junctions, both experimental and modeling studies show that the reduction of propagation velocity is proportional to the reduction of gap junction density or conductance. In the case of coupling through ICD field potential, since the experimental data are based on the effect of these mechanisms on conduction velocity (not a direct measurement of the field potential), there are significant discrepancies between different experiments, and between experiments and simulation studies (Rhett et al., 2013). One explanation of these differences is to consider a mixture of excitatory and inhibitory effects for each of these mechanisms and suppose that each experiment grasp one feature of these mechanisms based on the experimental condition. Such a mixed behavior was proposed for the ephaptic coupling in a previous study, where the voltage gated sodium channels of the ICD negatively impacted the conduction velocity unless more than 10% of the gap junctions remained active. Further reduction of gap junction density was reversed their impact (Kucera et al., 2002). In the case of capacitive coupling, also, we suggest that a mixture of excitatory and inhibitory effects take place; so that depending on the compartment on which the membrane potential is measured, different effects may be observed. In capacitive coupling, we have two capacitors that share a voltage node, but each end of these capacitors are connected to different intracellular voltage nodes that provide the main polarity of the capacitors. Since these capacitors have a different polarity (Figure ​(Figure1A),1A), discharge (depolarization) of one of them by action potential generation would charge (hyperpolarize) the other one. Still, these capacitors in series can pass the current, which would increase the potential in the next intracellular voltage node. The hyperpolarization of ICD membrane was reported in a previous modeling study, but due to the complex nature of their model it was impossible to dissociate the electrical field coupling from the capacitive coupling (Ge and Sperelakis, 1992). Figure 1 Capacitive coupling simulation. (A) The equivalent circuit of intercalated disk. (B) Cell arrangement in the final model. Colors show the membrane potential in all cells. (C) Membrane potential and extracellular voltage in different locations of the intercalated ... We have simulated ICD in the NEURON simulation environment (Hines and Carnevale, 1997). In our model, an equivalent circuit of the ICD connects 10 myocytes together in the ICD (Figure ​(Figure1B).1B). Our model could potentially simulate ion channels in the cleft and gap junction. Capacitive coupling is the property of membranes lacking ion channels. Therefore, in the Figure ​Figure1C,1C, we show results of this model where there is no gap junction and ion channels in the ICD. The results of this model clearly show that the capacitive coupling hyperpolarizes the neighboring membrane in the ICD and depolarizes the adjacent myocyte membrane to some extent. Overall, based on the abovementioned simulation we hypothesize that the capacitive coupling has mixed excitatory and inhibitory effects. Therefore, we suggest that action potential propagation models should be revised based on this finding.

Lightning is one of the most powerful and dangerous natural phenomena on the Earth. It has had a profound impact on human society. We will focus here on the so-called "cloud-to-ground" lightning discharges. These discharges can cause damage not only when they strike the structure directly but also when they hit ground nearby. In the case of overhead conductors, whether they are power or telecommunication lines, due to overvoltages produced, these discharges can cause outages, disturbances on the network, or failure of electronic components and/or electrical equipment. In order to mitigate lightning effects via effective technological solutions and protective measures, we need to know lightning parameters and have models of both lightning itself and its interaction with the strike object or system. We will focus on the so-called indirect or nearby lightning and its effects. The following topics will be covered: (1) specification of channel-base current, (2) return-stroke models, (3) calculation of lightning electromagnetic field, and (4) electromagnetic coupling between the lightning channel and overhead conductors. Both analytical and distributed-circuit model (based on generalized telegrapher's equations) approaches will be considered.

The A-Φ formulation has been proposed as a new paradigm for deriving computational electromagnetics methods with no low frequency breakdown, and that are more directly applicable to coupling into quantum physics problems of interest. This formulation utilizes equations developed in terms of the magnetic vector potential (A) and electric scalar potential (Φ), which are deemed more fundamental quantities for quantum applications than the electric and magnetic fields. Further, computational electromagnetics solvers developed from the A-Φformulation have been successful at overcoming many of the inherent multiscale limitations that exist for field-based solvers. This has been shown in recent work, where time domain integral equations (TDIEs) applicable to perfect electric conductor (PEC) objects were shown to be stable and accurate over broad frequency ranges. However, many quantum electromagnetics applications of interest are pursued at optical frequencies where approximating metals as PEC is no longer acceptable. Instead, these regions are more appropriately described with a Drude-Lorentz-Sommerfeld model; and so computational electromagnetics solvers applicable to multiscale geometries that can analyze these regions over very broad frequency ranges are needed. This current work begins to address this need by presenting for the first time in either frequency or time domain a set of A-Φ formulation surface integral equations applicable to simple, loss-free dielectric regions. To do this, we derive TDIEs based on recently developed integral representation of solutions to the wave equations for A and Φ. A rigorous functional framework that was used to analyze the stability of the PEC A-Φ formulation TDIEs is leveraged to determine appropriate combinations of integral equations and unknowns so that stable marching-on-in-time discretization approaches for the dielectric TDIEs can be developed here. The result is a set of A-Φ formulation TDIEs with appropriate discretization guidelines that can accurately and stably analyze dielectric regions at middle frequencies. Although not applicable at very low frequencies, these equations provide an essential step toward this goal by determining a baseline for combinations of equations and unknowns for dielectric regions within this formulation.

A method is presented for computing accurate solutions of Maxwell's equations in the presence of perfect electrical conductors (PECs) with sharp corners and highly curved surfaces using conventional nodal finite elements and a scalar/vector (S/V) potential formulation. This technique approximates the PEC with an impedance boundary condition (IBC) where the impedance is small. Critically, it couples both potentials through this boundary condition, rather than setting the scalar potential to zero. This permits cancellation of the tangential components of the vector potential, resulting in an accurate normal electric field. The cause for the inaccuracies that nodal methods experience In the presence of sharp PEC corners or highly curved PEC surfaces is elucidated. It is then shown how the inclusion of the scalar potential cures these deficiencies permitting accurate solutions. Spectral analysis of the resulting finite element matrices are shown validating the boundary conditions used. Examples are presented comparing a benchmark solution, conventional PEC and IBC boundary conditions, and the new S/V potential IBC on a PEC wedge and PEC ellipse. In both cases the new S/V IBC produces superior results.

We consider the use of the Supervised Descent Method (SDM) for 2D transverse magnetic imaging inside perfect electric conductor (PEC) enclosed electromagnetic imaging problems. When the electromagnetic imaging region is surrounded by PEC, and the background permittivity is lossless, classic optimization-based inversion algorithms such as Contrast Source Inversion sometimes provide degraded results compared to those obtained from unbounded domains. The SDM, by learning average search directions based on a large synthetic data set, may be able to avoid certain local minima that normally trap other optimization methods. Through the use of synthetic examples, we show that SDM can provide improved performance within an enclosed chamber.

Automatic power line recognition is a challenging task for an unmanned aerial vehicles (UAVs) power line inspection system. In this paper we proposed a power line recognition and tracking method for sequence aerial images. First, the power lines are enhanced by a kind of double-side filters; then, the Hough transform with parallel constraint is used for power lines recognition; finally, in the sequence image, the state of power lines are estimated, and the power lines are tracked with those estimation. The tracking could reduce the computation time and made the recognition robust. Our experiments on real image data captured from UAV demonstrate our method is effective for power line recognition in sequence image.

The classical Kelvin inversions in spherical geometry are revisited in the context of geoelectric imaging. A point source of current is outside a perfect electrically conducting (PEC) sphere or outside perfect magnetically conducting (PMC) sphere. Perfect electric conductor is very good conductor with zero electric resistivity. Perfect magnetic conductor corresponds to very good insulator with infinite resistivity. The sphere is embedded in a homogeneous whole space which has constant electric conductivity. Analytical solutions can be obtained by the method of images. The methods are described and numerical demonstrations based on them are presented.

Transient surges in one of the overhead conductors, due to direct lightning strike, causes crosstalk in other adjacent conductors. This is a common phenomenon observed in power lines, communication lines and electrified railway lines. The presence of finitely conducting ground influences the magnitude and wave shapes of the crosstalk currents and voltages and this phenomenon has not received sufficient attention earlier. In this paper, we investigate the crosstalk in multi-conductor lines above finitely conducting ground as a function of ground conductivity, height of the receptor conductor, and position of emitter source. It is shown that ground conductivity has a significant influence in the amplitude and wave shape of the crosstalk currents in multiconductor transmission lines.

The use of GPS technology continues to grow and recent accuracy. augmentations will generate ever more innovative applications. The issue of GPS use under or near electric power lines has been raised since some GPS documents have vague wamings about such use. First, GPS and the satellite microwave signals used to determine position, velocity, and time are described. Then the potential effects of electromagnetic interference and/or signal scattering from overhead conductors are evaluated analytically and with some practical measurements under transmission lines. This work demonstrates that it is unlikely that power line conductors will interfere with use of the GPS satellite signals.

Wet snowfall events often cause significant and damaging winter blackouts in Italy's power networks due to the formation of cylindrical snow sleeves on overhead conductors. In the last decade, observations at the WILD (Wet-snow Ice Laboratory Detection) monitoring station in the Italian western Alps allowed to thoroughly investigate wet-snow and to improve snow sleeve accretion models. These models were employed to develop a historical reconstruction of snow load over Italy based on MERIDA (MEteorological Reanalysis Italian DAtaset). Moreover, RSE developed WOLF (Wet-snow Overload aLert and Forecast), an operational forecast system specific for wet-snowfall events and snow sleeves formation on overhead lines. WOLF is based on the WRF model, which provides precipitation, wind and temperature fields, and on the Makkonen’s snow sleeve accretion model, which, depending on meteorological information, calculates the growth of predicted snow mass on reference conductors of the transmission and distribution power network in each domain cell. Past case studies showed that accuracy limitations were primarily due to the intrinsic uncertainty in modeled meteorological fields produced by a deterministic NWP forecast. Sensitivity tests with different model configurations and GCM drivers showed variable performances, without establishing an optimal configuration for the heterogenous set of snowfall events analyzed. In this work, we assess the benefits of a probabilistic multi-model approach, combining the resulting snow load predictions obtained from different model runs and exploring other post-processing methods suitable for wet-snow forecasting. We employed freely available output runs of NWP models from different providers such as the Italian Mistral open data hub (https://meteohub.mistralportal.it/app/datasets) and we compared results with observations of recent snowfall events over the western alpine area. Probabilistic forecasts for this specific application will be further investigated and refined over more case studies to reduce forecast uncertainty of the WOLF system during the next winter seasons.