Electric Circuit Theory Research Articles

Method of calculation of steady-state processes in electrical circuits

Purpose. Development of a method for calculating established periodic processes of complex shapeMethodology. Polynomial approximation of functions, numerical methods for solving integro-differential equations, mathematical apparatus of matrix algebra, computer programming and methods of electric circuit theory are used.Findings. As a result of modification of the known method for calculating transient processes, a method has been developed that allows you to directly perform the calculation of steady-state periodic processes. This will reduce the time of computer simulation of electrical processes in linear electrical circuits. An example of using the proposed method is shown. Based on the developed method, a computer program for calculating the steady-state process in the model circuit is worked out. This example shows a 45% reduction in CPU time compared to the use of known methods.Originality. Processes in electrical circuits are described by integro-differential equations. The approximation of functions of current derivatives to time by series on orthogonal Tchebyshev’s polynomials is used in their solution.When approximating functions, Chebyshev polynomials have uniform error in the whole range of argument change. It is advantageous stand out them from a number of other orthogonal functions. The proposed method uses a polynomial approximation not of the solution function itself, but of its derivative. The function itself is obtained with the help of integration operation. This operation has a small margin of error compared to the differentiation operation. The direct calculation of the steady-state periodic process is achieved by taking the initial conditions for currents and their derivatives at the beginning of the period as the values of the same functions at the end of the period. In the proposed method, integro-differential equations of state are transformed into linear algebraic equations. A method for creating a unified system of linear algebraic equations is proposed. The solution of this system allows you to perform directly the calculation of steady-state periodic processes.Practical value The developed method opens a new possibility of using a diverse apparatus of the electric circuits theory to work with images of currents. Based on this method, a universal software package is developed for calculating steady-state periodic processes in electrical circuits of arbitrary complexity. This will reduce the CPU time for modeling complex circuits.

Analysis of Processes Mechanized Oil Mining with the Methods Theory of Electrical Circuits

The authors investigate the problems of the development of the oil and gas complex at the last stage of operation, when oil is extracted by lifting. The main methods of lifting employed in the Russian Federation and the USA are described. A particular focus is placed on large water cuts at this stage of oil production. Literature on the issue under investigation is reviewed and the problem is set to analyze and construct models of oil production processes at the stage of well operation by lifting methods using network analysis (electrical circuits) in order to rationally manage all processes comprehensively. A typical flow chart of the oil production process by lifting methods is described. Technological processes of oil production are compared to processes in electric circuits. Thus the process of pumping purified formation water into injection wells by means of block cluster pumping units is similar to the process of recharging a battery using an electric power generator. The process of filling a production well with gas-liquid mixture displaced from the formation under pressure of injection wells is similar to the process of charging a capacitor from a battery, the process of lifting liquid from production wells using production pumps — to the process of discharging a capacitor on an active load. The simplified electrical diagram of a typical flow chart of oil production processes at this stage is given. Based on the given equivalent electrical circuit of technological processes, according to the laws of theoretical electrical engineering, models of the battery charging, capacitor charging and discharging processes are built. The table of correspondence of the parameters of technological and electrical circuits is presented on the basis of which the authors propose simplified models of the processes of pumping purified formation water into injection wells using unit cluster pumping stations, of filling a production well under pressure of the injection well, lifting liquid from production wells by means of suction pumps and conditions under which various operating modes of lifting processes are achieved.

Minimal Series–Parallel Network Realizations of Bicubic Impedances

An important open problem in the synthesis of passive controllers is to obtain a passive network that realizes an arbitrary given impedance function and contains the least possible number of elements. This problem has its origins in electric circuit theory, and is directly applicable to the cost-effective design of mechanical systems containing the inerter. Despite a rich history, the problem can only be considered solved for networks that contain at most two energy storage elements, and in a small number of other special cases. In this article, we solve the minimal network realization problem for the class of impedances realized by series–parallel networks containing at most three energy storage elements. To accomplish this, we develop a novel continuity-based approach to eliminate redundant elements from a network.

Langevin differential equations with general fractional orders and their applications to electric circuit theory

Multi-order fractional differential equations have been studied due to their applications in modeling, and solved using various mathematical methods. We present explicit analytical solutions for several families of Langevin differential equations with general fractional orders, both homogeneous and inhomogeneous cases. The results can be written, in general and special cases, by means of a recently defined bivariate Mittag-Leffler function and the associated operators of fractional calculus. The novelty of this work is to apply an appropriate norm on the proof of existence and uniqueness theorem, and discuss the application of Langevin differential equation with fractional orders in several interesting cases to the electrical circuit. Moreover, we investigate Ulam–Hyers stability of Caputo type fractional Langevin differential equation. At the end, we provide an example to verify our main results.

Accessing habitat suitability and connectivity for the westernmost population of Asian black bear (Ursus thibetanus gedrosianus, Blanford, 1877) based on climate changes scenarios in Iran.

Climate change, as an emerging phenomenon, has led to changes in the distribution, movement, and even risk of extinction of various wildlife species and this has raised concerns among conservation biologists. Different species have two options in the face of climate change, either to adopt or follow their climatic niche to new places through the connectivity of habitats. The modeling of interpatch landscape communications can serve as an effective decision support tool for wildlife managers. This study was conducted to assess the effects of climate change on the distribution and habitat connectivity of the endangered subspecies of Asian black bear (Ursus thibetanus gedrosianus) in the southern and southeastern Iran. The presence points of the species were collected in Provinces of Kerman, Hormozgan, and Sistan-Baluchestan. Habitat modeling was done by the Generalized Linear Model, and 3 machine learning models including Maximum Entropy, Back Propagation based artificial Neural Network, and Support Vector Machine. In order to achieve the ensemble model, the results of the mentioned models were merged based on the method of "accuracy rate as weight" derived from their validation. To construct pseudo-absence points for the use in the mentioned models, the Ensemble model of presence-only models was used. The modeling was performed using 15 habitat variables related to climatic, vegetation, topographic, and anthropogenic parameters. The three general circulation models of BCC-CSM1, CCSM4, and MRI-CGCM3 were selected under the two scenarios of RCP2.6 and RCP8.5 by 2070. To investigate the effect of climate change on the habitat connections, the protected areas of 3 provinces were considered as focal nodes and the connections between them were established based on electrical circuit theory and Pairwise method. The true skill statistic was employed to convert the continuous suitability layers to binary suitable/unsuitable range maps to assess the effectiveness of the protected areas in the coverage of suitable habitats for the species. Due to the high power of the stochastic forest model in determining the importance of variables, this method was used. The results showed that presence/absence models were successful in the implementation and well distinguished the points of presence and pseudo-absence from each other. Based on the random forests model, the variables of Precipitation of Driest Quarter, Precipitation of Coldest Quarter, and Temperature Annual Range have the greatest impact on the habitat suitability. Comparing the modeling findings to the realities of the species distribution range indicated that the suitable habitats are located in areas with high humidity and rainfall, which are mostly in the northern areas of Bandar Abbas, south of Kerman, and west and south of Sistan-Baluchestan. The area of suitable habitats, in the MRI-CGCM3 (189731 Km2) and CCSM4 (179007 Km2) models under the RCP2.6 scenario, is larger than the current distribution (174001 Km2). However, in terms of the performance of protected areas, the optimal coverage of the species by the boundary of the protected areas, under each of the RCP2.6 and RCP8.5 scenarios, is less than the present time. According to the electric circuit theory, connecting the populations in the protected areas of Sistan-Baluchestan province to those in the northern Hormozgan and the southern Kerman would be based on the crossing through the heights of Sistan-Baluchestan and Hormozgan provinces and the plains between these heights would be the movement pinch points under the current and future scenarios. Populations in the protected areas of Kerman have higher quality patch connections than that of the other two provinces. The areas such as Sang-e_Mes, Kouh_Shir, Zaryab, and Bahr_Aseman in Kerman Province and Kouhbaz and Geno in Hormozgan Province can provide suitable habitats for the species in the distribution models. The findings revealed that the conservation of the heights along with the caves inside them could be a protective priority to counteract the effects of climate change on the species.

Landscape resistance affects individual habitat selection but not genetic relatedness in a reintroduced desert ungulate

The long-term success of species reintroductions is strongly dependent on the availability of large areas of suitable habitat and the genetic make-up of the population. If available habitat is poorly connected this can hinder gene flow and lead to genetic fragmentation of the population, potentially increasing its extinction risk. We employed a conservation genomics approach in which we combined analyses of genetic structure with testing for potential landscape effects on habitat selection and gene flow in reintroduced Asiatic wild ass Equus hemionus ssp. in the Israeli Negev desert. Genetic structure and pairwise relatedness were first investigated followed by examination of landscape effects on individual habitat selection using records of GPS collared individuals. We then built habitat resistance surfaces and used electrical circuit theory to test for landscape effects on genetic relatedness. We detected weak genetic structuring, yet low spatial coherence among individuals from the same genetic cluster. Landscape variables had a significant impact on individual habitat selection, with wild ass avoiding steep slopes and habitats of low suitability as predicted by a species distribution model. However, the landscape genetic analysis revealed no effect of habitat resistance on genetic relatedness. These results suggest that gene flow in the reintroduced population is not impacted by landscape resistance. Indeed, the high mobility of the species may increase its resistance to the genetic effects of habitat fragmentation, at least over a small number of generations. We discuss other potential causes for the observed genetic structure including a behavioural effect. Our study highlights the importance of understanding species-habitat interactions for the long-term success of reintroductions.

Three-Saddle-Foci Chaotic Behavior of a Modified Jerk Circuit with Chua’s Diode

This paper investigates the chaotic behavior of a modified jerk circuit with Chua’s diode. The Chua’s diode considered here is a nonlinear resistor having a symmetric piecewise linear voltage-current characteristic. To describe the system, we apply fundamental laws in electrical circuit theory to formulate a mathematical model in terms of a third-order (jerk) nonlinear differential equation, or equivalently, a system of three first-order differential equations. The analysis shows that this system has three collinear equilibrium points. The time waveform and the trajectories about each equilibrium point depend on its associated eigenvalues. We prove that all three equilibrium points are of type saddle focus, meaning that the trajectory of (x(t),y(t)) diverges in a spiral form but z(t) converges to the equilibrium point for any initial point (x(0),y(0),z(0)). Numerical simulation illustrates that the oscillations are dense, have no period, are highly sensitive to initial conditions, and have a chaotic hidden attractor.

Comparison between electrical and optical properties of Carbon dots, silver nanoparticles and hybrid carbon/silver nanoparticles: Experimental evidence of the interaction of Carbon dots on silver nanoparticles

The comparison between electrical and optical properties of AgNPs, Cdots and Ag@Cdots were investigated. The synthesis of the nanoparticles was carried out via the microwave method as a quite simple and environmentally friendly method. The current–voltage curve characteristics of these nanoparticles were measured by using ITO (indium tin oxide) as a holder support material. These measurements were performed by two different electrical methods and the HOMO–LUMOband gap energy values (Eg) were obtained. The Eg values obtained for each nanomaterial were correlated with the optical properties, such as Surface Plasmon Resonance (SPR). Electrical resistance values were obtained from the electrical studies in the ITO/sample contacted electrically by two points configurations. The comparisons of the Ag@Cdots electrical resistance, Eg and nanoparticle size values provide important information about the interaction between their components. Electrical resistance data in conjunction with the electrical circuit theory, provide relevant information about the surface coverage of AgNPs with Cdots on Ag@Cdots. The simplicity of the methodology used suggest useful for further studies related to the topic of nanomaterials.

Innovative solution to enhance the Helmholtz resonator sound absorber in low-frequency noise by nature inspiration.

Sound absorbing elements commonly used to make quieter spaces are very desirable for high-frequency noise control. It is more attractive if it is possible to produce sound absorbing structures that perform well for a wide frequency range, especially in low-frequencies. In this regard, Helmholtz resonator array is a well-known structure but the maximum performance of each resonator unit in an array panel can only be achieved at resonance frequency that is dependent on its size. Therefore, a resonator array panel with equal size units has insufficient performance in a wide frequency range. Hence, the consideration of suitable sizes for each resonator in an array panel consisting of unequal size units is a key point to widen the frequency range of sound absorption. On the other hand, it seems that engineering science can be developed by nature inspiration. In addition, Fibonacci sequence is a famous mathematical model which describes the shape/ratio of different phenomena which exist in nature. In this paper, Fibonacci sequence is utilized to investigate Helmholtz resonator arrangement to increase both the amount of sound absorption coefficient and frequency bandwidth of absorption without changing the total volume of resonator array with equal size units. Analytical solutions based on the modified equivalent electrical circuit theory is used to calculate the sound absorption coefficient of the proposed panel with numerical experiments in MAPLE and COMSOL Multiphysics softwares to validate the proposed overall approach. Results show that the Fibonacci sequence is an optimum candidate to design a resonator-based sound absorber in low-frequency noise.

Triple Laplace Transform in Bicomplex Space with Application

In this article, we investigate bicomplex triple Laplace transform in the framework of bicomplexified frequency domain with Region of Convergence (ROC), which is generalization of complex triple Laplace transform. Bicomplex numbers are pairs of complex numbers with commutative ring with unity and zero-divisors, which describe physical interpretation in four dimensional spaces and provide large class of frequency domain. Also, we derive some basic properties and inversion theorem of triple Laplace transform in bicomplex space. In this technique, we use idempotent representation methodology of bicomplex numbers, which play vital role in proving our results. Consequently, the obtained results can be highly applicable in the fields of Quantum Mechanics, Signal Processing, Electric Circuit Theory, Control Engineering, and solving differential equations. Application of bicomplex triple Laplace transform has been discussed in finding the solution of third-order partial differential equation of bicomplex-valued function.

Application of Neural Networks in the Problem of Quantitative Analysis of Air Composition

Purpose of reseach is to develop a method for generating training data to enable the use of artificial neural networks (ANN) method in gas analyzer systems. The problem of increasing the accuracy of separate determination of gas concentrations in multicomponent mixtures under conditions of environmental parameters changes is considered. It is proposed to increase the accuracy of determining target gas concentrations by using the ANN method for joint processing of sensor signals.Methods: Training data for the neural network were generated using numerical experiments and mathematical simulation methods. To assess the accuracy of training, the standard deviation (SD) was used and the relative error was calculated. ANN training and research were conducted in the MATLAB environment (the Neural Networks Toolbox application). When developing mathematical models of gas sensors, the theory of electrical circuits, electronic theory of chemisorption and the adsorption theory of heterogeneous catalysis were applied.Results: A method for generating training data sets using mathematical models of gas sensors is described. The proposed training method has been tested on a specific task, in particular, a decision-making device based on ANN for a four-component gas analyzer has been developed. The efficiency of using neural networks for tuning out from the mutual cross-sensitivity of sensors was evaluated.Conclusion: A method for generating training data using simulation models is proposed, which allows automazing the process of training, research, choosing the architecture and structure of ANN and their testing. The method was tested. Based on the analysis of the obtained errors, conclusions are made about the efficiency of using neural networks to reduce errors caused by cross sensitivity at different concentrations of the main and interfering gases.

Improving the Efficiency of Measurements of Combustible Gases Concentration by a Thermocatalytic Sensor

Thermocatalytic sensors are widely used in gas analysis systems and have high reliability and low cost. However, errors in measuring the concentration of combustible gases related to the non-linearity of the conversion characteristic and the influence of ambient temperature fluctuations significantly limit the scope of their application.Purpose of reseach. Development of a method for measuring gas concentration by thermocatalytic sensors, which allows reducing measurement errors by tuning out due to ambient temperature influence and linearization of the conversion characteristic.Problems. They are as follows: to develop a method for temperature stabilization of a thermocatalytic sensor; to make a structural and functional scheme for the sensor activation; to obtain a mathematical description of the method and substantitation for tuning out as a result of temperature influence; to experimentally confirm the possibility of linearization of the sensor conversion function in the thermal stabilization mode.Methods. The mathematical description of the method applies the theory of heat transfer and the theory of electrical circuits with discrete signals. When analyzing existing solutions and synthesizing the device, methods for calculating circuits with nonlinear elements and the theory of measurement systems have been used. The real conversion function has been obtained through an experimental method.Results. A method for measuring gas concentration by a thermocatalytic sensor with the use of a microcontroller and PWM has been developed. It allows reducing errors due to tuning out as a result of ambient temperature influence. A mathematical description of the method has been given. An experiment has been performed. It demonstrates the effectiveness of using temperature stabilization to linearize the conversion characteristic.Conclusion. The paper proposes a method for temperature stabilization of thermocatalytic gas sensors. The method makes it possible to increase the accuracy of measurements by tuning out due to the influence of temperature fluctuations and linearization of the conversion function. The possibility of linearization of the sensor function has been experimentally confirmed. It characterizes the dependence of the output signal on the concentration of combustible gas. Using this method allows you to reduce the cost of the sensor, improve the quality factors of the sensor, such as the reliability and stability of parameters.

The methodology for design of autonomous power supply system of oil producing company optimized on length and number of generation centers

Improving energy efficiency and reducing the cost of creating an electrical complex of autonomous power supply for an oil-producing enterprise is an urgent problem and requires a rational solution. The goal is the construction of energy-efficient electrical systems of autonomous power supply for oil-producing enterprises, leading to a reduction in the unit cost of electricity per unit of production. A methodology for constructing an autonomous power supply system for an oil producing enterprise, optimized in length and number of generation centers is present. The results presented in the work were obtained using methods of the theory of electric and magnetic circuits, theory of electric drive, methods of optimization of power supply systems, methods of mathematical and computer modeling. The configuration of the power supply system of oil producing enterprises and the efficiency of its work is analyze. To test the efficiency of the methodology, the power supply system of an oil producing enterprise is simulate in the RTDS software package. The results of the work were introduced and used in the creation of energy-efficient electrical systems for autonomous power supply to oil-producing enterprises based on autonomous diesel generators and optimized by the length of power lines and the number of generation centers. Implementation of the results of the work allows reducing the specific energy consumption per unit of extracted products and reducing the cost of building an energy-efficient electrical complex of autonomous power supply for oil-producing enterprises.

Frequency bifurcation in a series-series compensated fractional-order inductive power transfer system

This paper reveals and analyzes the frequency bifurcation phenomena in the fractional-order inductive power transfer (FOIPT) system with series-series compensation topology. Using fractional calculus theory and electric circuit theory, the circuit model of the series-series compensated FOIPT system is first proposed, then taking the case of a single variable fractional order as an example, three frequency analytical solutions of frequency bifurcation equation are solved by using Taylor expansion method. By analyzing the three bifurcation frequencies solved, it can be found that the frequency bifurcation phenomenon can be effectively eliminated by controlling the fractional order, and the boundary of critical distance and critical load is reduced, thereby expanding the working range of the conventional inductive power transfer (IPT) system. Furthermore, the output power and transfer efficiency at the three bifurcation frequencies are analyzed, it can be observed that the output power and transfer efficiency at the high bifurcation frequency and low bifurcation frequency are close and basically keep constant against the variation of transfer distance, and the output power is obviously higher than that at the intrinsic frequency. In addition, the output power at the three bifurcation frequencies can be significantly improved by adjusting the fractional order. Finally, the experimental prototype of FOIPT is built, and the experimental results verify the validity of theoretical analysis.

A little-known minimum concerning resistors in series and in parallel

In the elementary theory of electrical circuits, the series connection of n identical resistors has an equivalent resistance n2 greater than the equivalent resistance of their parallel connection. More briefly, the series/parallel ratio is n2. We show that if the resistors are not all identical, the series/parallel ratio is greater than n2 and can never be less than n2. This little-known minimum has been demonstrated previously, using the theorem that the arithmetic mean of non-negative numbers always equals or exceeds their geometric mean. Here we present a simple proof that avoids using the theorem. If the n resistors differ only slightly, the series/parallel ratio is still n2 to first order in their differences. Because this ‘weaker’ form has long been known, we discuss only briefly its significance for electrical metrology. We present a Monte Carlo simulation of the series/parallel ratio for two resistors, one of which varies in accordance with a Gaussian density distribution defined by three tolerance ranges, and we compare the simulation graphically with the theoretical series/parallel ratio for each of these ranges. This theoretical ratio is essentially a plot of the density distribution of the square of a Gaussian variable, or equivalently of a chi-squared distribution on one degree of freedom. Finally, we note an interesting connection between the minimum and the second law of thermodynamics.

Mathematical model of an electric vehicle with a non-flat battery of photovoltaic converters

One of the major environmental problems is emissions of CO2 and other harmful substances from motor vehicles (MV). According to the tests, the most environmentally friendly MV (measurement of emissions on MVs) are electric vehicles (EV). But a low emission level can only be ensured by the use of environmentally friendly sources of electricity used to charge EV: hydroelectric power plants, wind power plants, tidal, geothermal, wave, solar power plants, etc. However, the transmission of electric energy is connected with losses. One of the ways to use them is the application of batteries of photovoltaic converters (PVC) within the EV structure as the most suitable in terms of weight and size characteristics. The use of PVC in MV is not a new idea, but due to the increase in the efficiency of PVC, their relevance becomes more obvious. Purpose of work: development of mathematical models, scientific substantiation and rationale of the calculation method of EV energy efficiency increase by enlarging the cruising range when using PVC batteries. Research methods: methods of ground MV movement theory, system design, theory of electric circuits, mathematical modeling, etc. Results: development and scientific substantiation of the calculation method for a non-flat PVC battery within the EV structure and its effect on run or mileage change. Summary: 1) the mathematical model of EV rectilinear motion on flat non-deformable horizontal ground, suitable for the study of the processes of energy exchange between the EV and PVC batteries and the effect of these processes on the mileage, has been developed; 2) the application of the calculation method for non-flat PVC batteries to be used within the EV structure has been scientifically substantiated.

On Magnetically Coupled Coils Parameter Calculation

Abstract ANSYS Q3D Extractor tool (AQ3DE), using the quasi-static solvers (method of moments, integral equations and FEMs), is very efficient for computing and simulating two- and three-dimensional electromagnetic field. This simulation is used to extract parameters of interest, such as: resistance (R), conductance (G), self-inductance (L), mutual inductance (M) and capacitance (C). These parameters can be further used to optimize and to obtain automatically the design of a wireless power transfer systems (WPTS). The resulting matrices allow the generation of new matrices for any selected parameters. To complete the analysis, the model which is computed will be exported as an equivalent circuit. In this paper, starting from a given WPTS, using AQ3DE tool, the parameters of interest (R, G, L, M, C) were automatically calculated, and the SPICE equivalent circuit was obtained. The analysis was performed for two different distances between the emitter and the receiver. The electrical circuit theory was used for the system analysis of magnetically coupled coil (MCC) system. Starting from the parameters extracted by the AQ3DE tool, the performance of the WPTS has been analysed both in time and frequency domain.

GEOMETRIC AND ELECTROPHYSICAL PARAMETERS OF ARMATURE WINDING OF ELECTROMECHANICAL CONVERTER OF INERTIAL ENERGY STORAGE FOR SUBURBAN TRAINS

Purpose. To establish analytical expressions of machine constant and electromagnetic parameters for a specific circuit of the armature winding of an electromechanical converter of an inertial energy storage device, which is a DC electric machine with a semiconductor switch and excitation from permanent magnets. Methodology. For research the theory of electrical circuits is used to create a mathematical model of the processes of electromechanical energy conversion in an inertial storage device. The plots method is used to find the mutual inductance of the armature winding coils, which are presented in the form of infinitely thin single-turn contours of rectangular shape, located in three-dimensional space. Results. Mathematical models of the processes of electromechanical energy conversion in an inertial storage device are obtained reflecting the relationship between the exchange energy and drive power with geometric and electrophysical parameters of both the energy accumulator and the system of its electromechanical converter. A connection of the parameters of machine constant, active and inductive resistances with the configuration, wiring diagram and the geometric dimensions of the armature winding has been established. The wiring of sections in the phase of the armature winding depends on the required value of the voltage and current of the machine. The possibility of regulating the voltage of the drive by switching on and off the working phases of the system of electromechanical converter, as well as by changing the angle of the load is shown. Originality. Mathematical models are obtained that relate the indicators of the energy of exchange and the power of the drive to the geometrical and electro physical parameters of both the energy accumulator and the system of its electromechanical converter. A feature of these models is operating with an average value of induction and machine constants when determining the electromotive force and electromagnetic moment. Practical value. Recommendations are developed for determining the machine constant and electromagnetic parameters of electromechanical inertial energy storage devices. This allows to evaluate the properties of devices of this type in the modes of storage and delivery of energy during their operation on board the rolling stock.

РАЗРАБОТКА МЕТОДИКИ ОПРЕДЕЛЕНИЯ МЕСТА ОДНОФАЗНОГО ЗАМЫКАНИЯ НА ЗЕМЛЮ ВОЗДУШНОЙ ЛИНИИ ЭЛЕКТРОПЕРЕДАЧИ НАПРЯЖЕНИЕМ 6(10) кВ С УЧЕТОМ КЛИМАТИЧЕСКИХ ФАКТОРОВ

Актуальность. Одной из основных причин высокой аварийности и отключений в распределенных системах электроснабжения 6(10) кВ кустов нефтяных скважин являются повреждения воздушных линий электропередачи вследствие однофазных замыканий на землю. Широко проводимые исследования по определению места возникновения однофазного замыкания на землю установили корреляцию между точностью определения и большим количеством изменяющихся факторов, таких как параметры режима работы, параметры воздушной линии электропередачи, вид повреждения, величина переходного сопротивления, сопротивление грунта и прочие, принимая их усреднённые значения, не зависимо от изменения климатических условий. Нормирование технических средств определения места возникновения однофазного замыкания на землю по инструментальным погрешностям без учёта методической составляющей обуславливает погрешность определения места повреждения, достигающую 30 %. Таким образом, актуальны исследования, направленные на определение первичных параметров ЛЭП и минимизацию методической погрешности определения места повреждения ЛЭП с учётом климатических факторов. Цель исследования заключается в повышении точности определения места возникновения однофазного замыкания на землю линии электропередачи 6(10) кВ путём разработки методики, учитывающей влияние климатических факторов. Методы. Учтены основные физические процессы распространения электромагнитной волны в линии электропередачи. Использованы основные положения теории электрических цепей и электромагнитного поля; алгоритмы пакета MATLAB Simulink. Результаты. Разработан алгоритм, позволяющий определить расстояние от понижающих подстанций 6(10)/0,4 кВ до места возникновения однофазного замыкания на землю в распределительных сетях кустов нефтяных скважин с учетом конструктивных особенностей линии электропередачи и климатических факторов. Разработана в среде MATLAB Simulink имитационная модель распределительной сети 10 кВ, питающей кусты нефтяных скважин, учитывающая зависимость первичных параметров линии электропередачи от климатических факторов и удельного сопротивления грунта.

Plasma arc interactions with electric circuit: Variability of arc V-I characteristic

The main goal of this letter is the investigation of the interaction of generated plasma arc in SF6 circuit breakers with electric circuits. According to the electric circuit theory, when there is a nonlinear element in the circuit such as an arc, the intersection of the nonlinear V-I curve of the arc and the circuit V-I curve can be used to find the circuit operating point. In this letter the correctness of this approach for finding the system operating point is interrogated, by using a multi-physic model, including the Navier-Stokes equations and standard K-εturbulent model for modeling the dynamic of the SF6 gas, heat equation for calculation of the SF6 gas temperature, Maxwell equations for electromagnetic fields modeling, gas state equation for taking into account the temperature dependency of SF6 gas properties, and Kirchhoff's voltage and current laws equations. Numerical studies have been performed during the closing operation of a puffer-type 72.5 kV SF6 circuit breaker.