Relevant bibliographies by topics / Currents and voltages asymmetry

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Currents and voltages asymmetry'

Author: Grafiati
Published: 30 May 2022
Last updated: 31 May 2022

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Journal articles on the topic "Currents and voltages asymmetry"

1

Marciniak, Lubomir, and Mateusz Piątek. "The influence of the network asymmetry on the settings and sensitivity of an earth fault protection using higher harmonics." E3S Web of Conferences 84 (2019): 02008. http://dx.doi.org/10.1051/e3sconf/20198402008.

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Detection of high resistance earth faults in medium voltage networks is an important problem due to ineffectiveness of traditional earth fault protections. Such short circuits can be detected by the criterion of a reactive power of higher harmonics for zero sequence current and voltage. The main problem is determination of the power setting value in the protection, which depends on the asymmetry of phase-to-earth capacitances and higher harmonics in supply voltages, which are generated by non-linear loads. The intensive tests of the asymmetry of the zero sequence currents and voltages for harmonics and their reactive power have been carried out in 15 kV compensated network as a function of all relevant parameters, i.e.: maximum capacitance deviation of the network and protected line, percentage content of harmonics in supply voltages, capacitive current of the network and the line. It has been shown that third harmonics of the zero sequence voltage and current are the best suited for practical use, since the asymmetry reactive power of these components is the smallest among the considered harmonics and the protection sensitivity will be the highest.
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2

Romanova, Victoria, and Sergey Khromov. "Effect of asymmetry of supply voltages on asynchronous motor operation modes." E3S Web of Conferences 58 (2018): 03013. http://dx.doi.org/10.1051/e3sconf/20185803013.

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Effect of asymmetry of supply voltages on asynchronous motor operation modes was investigated using the computer-aided simulation experiments, the software complex Matlab and the package program Simulink. Publication relevance is determined by the necessity for performance of comparative analysis of the level of effect of asymmetry of supply voltages on asynchronous motors of different series and power capacities. Six motors of three different power capacities (5.5, 55, 160 kW) and of two different series (4A, AI) were modeled for investigation. The value of asymmetry of supply voltages was changed from 0 to 5%. The motor shaft load was changed from 0 to 120% of the motor rated load. Comparison of dependencies of the phase currents on the voltage unbalance ratio by reverse sequence (K2U) of asynchronous motors with short-circuited rotor series 4A and AI was made. The analysis and discussion of obtained investigation results were performed, recommendations on operation of asynchronous motors series 4A and AI in conditions of asymmetry of supply voltages were given.
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Marius Bîrlea, Nicolae, and Sînziana Iulia Bîrlea. "The current-voltage relation of a pore and its asymptotic behavior in a Nernst-Planck model." Journal of Electrical Bioimpedance 3, no. 1 (July 23, 2019): 36–41. http://dx.doi.org/10.5617/jeb.296.

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Abstract A model for current-voltage nonlinearity and asymmetry is a good starting point for explaining the electrical behavior of nanopores in synthetic or biological membranes. Using a Nernst-Planck model, we found three behaviors for the calculated current density in a membrane's pore as a function of voltage: a quasi-ohmic, slow rising linear current at low voltages; a nonlinear current at intermediate voltages; and a non-ohmic, fast rising linear current at large voltages. The slope of the quasi-ohmic current depends mainly on the height of the energy barrier inside the pore, w, through an exponential term, ew. The magnitude of the non-ohmic linear current is controlled by the potential energy gradient at the pore entrance, w/r. The current-voltage relationship is asymmetric if the ion's potential energy inside the pore has an asymmetric triangular profile. The model has only two assumed parameters, the energy barrier height, w, and the relative size of the entrance region of the pore, r, which is a useful feature for fitting and interpreting experimental data.
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Гольдман, Е. И., С. А. Левашов, and Г. В. Чучева. "Особенности характеристик устойчивых к полевым повреждениям структур кремний-сверхтонкий окисел-поликремний." Журнал технической физики 53, no. 4 (2019): 481. http://dx.doi.org/10.21883/ftp.2019.04.47444.9011.

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AbstractResults of studying the features of the current–voltage ( I – V ) and capacitance–voltage characteristics of field-resistant silicon–ultrathin oxide–polysilicon structures are presented. It turns out that the total recharging of localized electron states and minority carriers concentrated near the substrate–insulator interface, which occurs with a variation in the field voltage, is an order of magnitude higher than that of samples susceptible to damage by the field stress effect. The tunneling I – V characteristic is significantly asymmetric; notably, the current flowing from the field electrode into the silicon substrate is several orders of magnitude lower when compared with the current flowing from silicon to polysilicon at identical external voltages dropping across the insulating layer. To explain this asymmetry, it is assumed that a potential barrier in the transition layer from polysilicon to oxide, which separates the semiconductor electrode and substrate, has a height of ~1 eV and therefore always hinders electrical transport; for reverse currents, this barrier stops limiting the conductivity as soon as the tunneling level becomes higher than it.
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Zhezhelenko, I. V., V. E. Kryvonosov, and S. V. Vasilenko. "Criteria for Detecting Turn-To-Turn Short Circuit in Stator Windings Using Vector Analysis of Electric Motor Phase Currents." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 3 (June 4, 2021): 202–18. http://dx.doi.org/10.21122/1029-7448-2021-64-3-202-218.

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At industrial enterprises, seaports, ships, more than 80 % of all electrical engineering equipment is asynchronous motors. In a number of cases, asynchronous motors operate with a sharply variable load, in an aggressive environment; herewith they receive power from the network with deviations of the power quality indicators from the normative ones, which causes their high damageability. Turn circuits in the stator windings account for about 40 % of cases of damage to the insulation of the asynchronous motors windings. Untimely detection of the initial moment of the appearance of defects in the asynchronous motors or disruption of the operating modes of the supply network and current circuits result in emergency situations of the electrical complex, equipment downtime and damage. The article discusses the issues of diagnostics of non-full-phase modes of current circuits, mains voltages and turn circuits in the stator windings of the asynchronous motors that receiving power from the networks in conditions of voltage asymmetry. The analysis of the vector diagrams of currents, voltages and additional phase angles of the phase currents displacement arising from the asymmetry of the mains voltages and turn circuits in the stator windings has been fulfilled. The results obtained made it possible to formulate criteria for identifying the initial moment of the turn circuit and two-phase modes, both in the network and in current circuits, in stationary modes. A method for non-destructive testing of the asynchronous motors state as well as a device for its implementation has been developed. The method is based on comparing the vectors of the measured phase currents of the asynchronous motors with their calculated values. The article presents the results of modeling the change in the vectors of phase currents from the number of closed turns in the winding of the asynchronous motors. The power series of asynchronous motors was established, for which the sensitivity of detecting the initial moment of the turn-to-turn short circuit is maximum. Analytical results of the dependence of the sensitivity coefficient for turn-to-turn short circuit on the absolute increment of the modules of phase currents and the corresponding phase angles have been obtained.
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Palka, Ryszard, Konrad Woronowicz, and Jan Kotwas. "Current mode performance of a traction linear induction motor driven from the voltage converter." Transportation Systems and Technology 4, no. 3 suppl. 1 (November 19, 2018): 105–14. http://dx.doi.org/10.17816/transsyst201843s1105-114.

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Background: The paper deals with the modelling of a traction Linear Induction Motor (LIM) for public transportation. Typical problems arising from the electromagnetic finite element model development are described. The end effect causes asymmetry of phase impedances of the LIM. Because of that, if the LIM is supplied from the voltage inverter, which is usually the case, the phase currents become asymmetric. This causes performance calculation discrepancies in models that assume phase current symmetry. Aim: The aim of the paper is to develop a method for calculating the imbalanced three-phase LIM currents to precisely predict the LIM performance. Methods: Here, a method is developed to calculate the LIM phase current asymmetry by means of a self-developed electromagnetic finite element program – ELMAG, capable of adapting mesh generation based on Reynolds, Péclet and skin-depth numbers. Results: The calculated asymmetric currents are used in a real size traction LIM calculation in COMSOL, to derive the performance characteristics for comparison with the results achieved when supplying the LLIM with the symmetric three phase current. Conclusion: These results show that the natural asymmetry of the currents is an important factor that must be considered in appropriately calculating the LIM performance.
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Warzecha, Adam, and Witold Mazgaj. "Effects Generated by the Magnetic Core Anisotropy of an Induction Motor." Energies 13, no. 9 (May 1, 2020): 2189. http://dx.doi.org/10.3390/en13092189.

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A theoretical analysis enables effects generated by the magnetic core anisotropy of an induction motor to be determined qualitatively. Relationships formulated between currents and magnetic flux linkages that are associated with three-phase stator windings enable the qualitative determination of spectra of currents or voltages of a typical induction motor. These relationships account for nonlinear and anisotropic magnetization characteristics of the motor core, both during idle running and motor starting. Based on these relationships, components of the amplitude Fourier spectra of symmetrical components of currents or voltages, which are useful in the diagnostics of stator or rotor core anisotropy, were selected. Field calculations were performed for the core of a two-pole 5.5 kW motor supplied by three-phase sinusoidal currents. The components of the induced voltage Fourier spectra in both the idle running and short-circuit state were similar to analogous components predicted based on theoretical studies. The components occurring in the spectra, which were obtained based on field calculations, were distinguished in the measured spectra of the symmetrical components of the phase currents. These components were applied to estimate representative current signal levels in the diagnostics of motor core anisotropy. Relative values of these signals did not exceed 60 dB; however, they were significant for assessing the internal asymmetry level of the motor stator or rotor core. The results of laboratory measurements confirmed the results of the theoretical analysis.
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Artemenko, M. Yu, Y. V. Kutafin, V. M. Mykhalskyi, S. Y. Polishchuk, V. V. Chopyk, and I. A. Shapoval. "SHUNT ACTIVE FILTER CONTROL OF A THREE-PHASE THREE-WIRE NETWORK IN THE COORDINATE SYSTEM OF THE TWO WATTMETERS METHOD." Tekhnichna Elektrodynamika 2021, no. 5 (August 16, 2021): 11–20. http://dx.doi.org/10.15407/techned2021.05.011.

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A combined control system for a shunt active filter in the coordinate system of the two-wattmeters method has been proposed, which, depending on the conditions of use, implements one of the four active filtration strategies, optimal according to a certain quality indicator. The most promising is the proposed integral strategy for active filtration control with the reference vector of line voltages of direct sequence, which provides symmetric sinusoidal currents of the network and the minimum pulsation of power consumption for the almost identical energy-saving effect as the concept of S. Fryze. New formulas for calculating the energy-saving effect and pulsations of the instantaneous power in a three-phase system of power in the case of the formation of an active current in the transmission line in the conditions of asymmetry of loading voltage and linear asymmetric load have been developed. Simulation studies have confirmed the adequacy of the proposed strategies and calculations. References 15, figures 5, tables 2.
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AFANAS’YEV, Alexander A. "Equations of a magnetoelectric valve motor for loop closures of the stator winding." Elektrichestvo 11, no. 11 (2020): 47–52. http://dx.doi.org/10.24160/0013-5380-2020-11-47-52.

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The article considers the differential equations of a switched permanent magnet motor in which a short-circuit fault occurred in one or more turns in one of parallel stator winding branches. Owing to the occurred asymmetry of the phase quantities, symmetrical line-to-line voltages at the stator winding terminals are assumed. It is shown that turn-to-turn short-circuit faults give rise to non-sinusoidal and imbalanced phase currents and voltages at the nominal load torque on the shaft, and it should be noted that initially, a growth of the frequency and ratios of currents in the phases with an increase in the number of short-circuited turns are observed, after which the phase currents tend to decrease (with a continuing growth in the current through the short-circuited loop), and the rotor stalling occurs. The growth of motor rotation frequency and decrease of its overloading capacity take place due to a growth in the demagnetizing effect of armature reaction caused by the current through the short-circuited stator winding turns.
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Chernyshov, Maxim, Valery Dovgun, Sergei Temerbaev, and Zumeyra Shakurova. "Hybrid power quality conditioner for three-phase four-wire power systems." E3S Web of Conferences 178 (2020): 01009. http://dx.doi.org/10.1051/e3sconf/202017801009.

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The article considers a hybrid power quality conditioner (HQPC) for 3-phase 4-wire systems with a distributed modular structure. Some conditioner modules provide compensation for the component currents and voltages that form the negative and zero sequence systems. The open structure of the HQPC, consisting of independent modules, allows compensating for distortions of currents and voltages of the 3-phase network caused by the nonlinear nature and asymmetry of single-phase loads. The compensation characteristics of the proposed conditioner were researched using a model developed in the MatLab environment. The simulation showed that the proposed conditioner can ensure normalization of power quality in 3-phase 4-wire system at various modes of network operation.
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Dissertations / Theses on the topic "Currents and voltages asymmetry"

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Yu, Jian-Guo. "Computer analysis of touch voltages and stray currents for DC railways." Thesis, University of Birmingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515818.

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The study described in this thesis is concerned with the touch and step voltage problems due to rail potential 'rise 'and the electro-chemical corrosion problem due to stray 'current in DC powered electric I railways. The two problems are interrelated and are both affected by system design philosophies and by operational conditions. In the past, various approaches to these problems have been based on experience accumulated over many years of railway construction and operation. However, without detailed 'studies, it has not been possible to' make realistic comparisons between the different approaches on a scientific basis. In order to assess the merits and demerits of different approaches, objective parameters are proposed in this thesis: the worst-case rail potential, rail potential envelopes, the total stray current and the gross leakage charge. In order to calculate these objective parameters and obtain other detailed data, mathematical` models are constructed and a comprehensive range of computer simulation software developed. These include both static and, dynamic models. Static models are used to evaluate the objective parameters under assumed conditions. Dynamic models, which are integrated simulators that combine the static models with the multi-train simulator, are used to simulate 'practical railway operations. Finally, the theoretical models are validated by practical tests, both in laboratory and on-site. Favourable agreement is obtained between simulation and test results.
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Kiuru, Wille. "Synchronous generator rotor position estimation from stator and rotor terminal currents and voltages." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194196.

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This thesis presents an alternative method for measuring the rotor position of a synchronousgenerator, without the use of sensors to measure the rotor position. The method uses thecurrent and voltage measurements on the stator and rotor terminals from the protectionrelays. The rst step is to investigate how the rotor position can be estimated basedon the available measurement data. It was found out that the rotor position couldn'tbe estimated during dynamic state operation, when directly solving it from measurementdata. This is due to the presence of the eld and d-axis damper winding current dynamics,including the q-axis damper winding current. In order to achieve this, multiple stepsconsisting of dierent methods for estimating the rotor position were utilized. The rststep is to estimate the rotor position during steady state. The second step estimates therotor position iteratively based on initial values. This method is useful during a dynamicstate operation. The initial values are obtained from the rst step at the start of a dynamicstate operation. The nal step predicts the rotor position based on previous data. It isused during cases when the second step fails to estimate the rotor position accurately.Due to insucient data for estimating the rotor position during saturation, the eects ofsaturation for the simulated synchronous machine were not considered.
Detta projekt presenterar en alternativ metod för estimering av rotorvinkeln för en synkronmaskin med utpräglade poler, utan användning av sensorer. Metoden som används är att estimera rotorvinkeln genom uppmätt data av strömmar och spänningar från stator och rotor terminaler inom skyddsreläer. Första steget är att undersöka ifall rotorvinkeln kan bestämmas direkt ur mätdata. Det visade sig att rotorvinkeln kunde inte estimeras vid en dynamisk fas, genom att lösa rotorvinkeln direkt från mätdata. Detta på grund av strömmderivatan i fält och dämplindningen i d-led, samt strömmen i dämplindningen i q-led. För att uppnå detta, flera olika steg baserad på olika metoder användes för att estimera rotorvinkeln. Det första steget går ut på att estimera rotorvinkeln i ett stabilt läge. Det andra steget estimerar rotorvinkeln iterativt baserad på initialvärden. Denna metod är användbar vid ett icke-stabilt läge. Initialvärdena erhålls från steg ett vid början av ett icke-stabilt läge. Det slutliga steget förutsäger rotorvinkeln baserad på tidigare data. Den används då steg två misslyckas att estimera rotorvinkeln noggrant. På grund av otillräcklig data för att estimera rotorvinkeln under mättnad så togs inte mättnadsfenomen till hänsyn för den simulerade synkronmaskinen.
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Ягуп, Катерина Валеріївна. "Покращання енергетичних показників електротехнічних систем із застосуванням пошукової оптимізації на комп'ютерних моделях." Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35541.

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Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.09.03 – електротехнічні комплекси та системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018. Розглядаються методи оптимізації режимів систем електропостачання з несиметричними і нелінійними навантаженнями з метою підвищення енергетичних показників і розрахунку симетро-компенсуючих пристроїв. Обґрунтовано необхідність і можливість застосування комп'ютерних засобів, розроблено узагальнені алгоритми реалізації пошукової оптимізації. Розроблені методи успішно застосовані для оптимізації режимів в трипровідних і чотирипровідних системах, в тому числі в системах з взаємно-зв'язаними індуктивностями, в системах залізничного електропостачання, в системі з нейтралером, в системах живлення асинхронних двигунів, освітлювальних приладів високого тиску, в системах з силовими активними фільтрами, а також для випадків кількох навантажень з урахуванням вкладу кожного з них в зниження енергетичних показників системи.
Thesis for a Doctor’s degree in Engineering Science by specialty 05.09.03 – Electrical Engineering Complexes and Systems. – National Technical University "Kharkov Polytechnic Institute", Kharkiv, 2018. The dissertation is devoted to the development and research of optimization methods of power supply systems modes in electrotechnical systems with asymmetric and nonlinear loads in order to increase the energy indices and calculate the parameters of symmetry-compensating devices using mathematical and computer models, and using search engine optimization implemented with the use of modern software of computer mathematics. The necessity and the possibility of using computer tools for solving set tasks are substantiated. The generalized algorithms for implementing search engine optimization using modern software packages are developed. The possibilities of applying different optimization criteria for solving the problems of increasing the energy indices of power supply systems with asymmetric and nonlinear loads are shown. The properties of the search engine optimization system have been found to extrude the inappropriate element of the synthesized device, as well as the possibility of releasing the optimization variables by increasing their amount, which allows us to get ahead of a faster locating of the local minimum and then recalculate the parameters corresponding to the global minimum are shown. The developed method of search optimization using the models of power supply systems has been successfully applied for optimization of regimes and synthesis of symmetry-compensating devices in three-phase three-wire and four-wire systems of power supply. The possibilities of using the optimization tools for Mathcad and Matlab software packages are considered, in particular, using zero-order methods that do not require the calculation of derivatives, such as the deformed polyhedron method and the conjugate gradient method. The algorithm of load equivalence is proposed, with the help of which the symmetrical and asymmetric parts of the load are allocated. After this, the parameters of the balancing device are determined with sufficient accuracy by means of the Steinmetz and Kennely formulas. The method of currents direct symmetric component rotation with the preservation of symmetry and the mode of full reactive power compensation is proposed. For four-wire systems, the use of a generalized reactive element in a symmetry-compensating device is proposed, which accelerates the process of achieving the optimal solution. The method of determining the optimal mode based on the decomposition of the power supply system, which improves the convergence of the solution processes, is developed. Systems of power supply containing inductively coupled elements are considered. The calculation of the symmetry-compensating device of the traction system of the alternating current railway power supply is considered. A four-wire system with a neutralizer was studied, with the help of search engine optimization the parameters of the symmetry-compensating device were determined which allows to balance and counterbalance such a system. The possibilities of optimization of the regime in the power system of asynchronous motors, including the asymmetry of the supply network, are shown. Compensation of reactive power allows here to reduce the consumed currents and increase the efficiency of the system. To find the optimal modes of systems with an arc discharge, visual models have been developed that are adapted for use with the SimPowerSystem library elements. With the help of these models, the possibilities of increasing the power indices of arc discharge power supply systems, including high-pressure lighting devices, are investigated. It was shown that the optimization of the power factor alone, calculated with the help of the pro-posed methods, leads to decrease in the current consumed by the fundamental harmonic, which substantially reduces the losses in the transmission lines. For a thyristor compensator with single-stage switching, the advantage of symmetric control is proven, which greatly improves the spectrum of harmonics of supply currents. The use of the search optimization method to increase the power factor is shown without the use of traditional rather complicated control systems by power active filters. Comparison signals are used as control signals, synchronized with the phase voltages of the supply system. The amplitudes of these signals are accepted as optimization variables, and the optimization criterion is determined by the balance of active power in the system, which is characterized by the stabilization of the periodic voltage on the storage capacitor of the power active filter. The problems of synthesis of symmetric-compensating devices for several asymmet-rical loads in parallel and cascade connection are considered. The task is to determine the parameters of the symmetric-compensating devices for each of the loads separately, and the contribution to the creation of asymmetry and the generation of reactive power of each connected load must be taken into account. This problem is solved by the method of search optimization, and it is shown that, in forming the objective function, currents in the feeders, supplying energy from the point of connection of the load to the network to the common point of connection of the load and the symmetric-compensating device. It is effective to use the developed decomposition method, which makes it possible to simplify and accelerate the determination of the optimal regime of the system under study, taking into account the contribution of each load to the reduction of the energy parameters of the system as a whole. The case is also analyzed when two loads consisting of both unbalanced linear and nonlinear loads are simultaneously connected to the network. Optimization of the regime with increasing power factor is achieved by using a parallel power active filter with control over the proposed optimization algorithm. Methods and algorithms of search optimization developed for the purposes of increasing the energy indicators of power supply systems with asymmetric and nonlinear consumers developed and presented in the thesis work are characterized by high accuracy, the maximum possible use of computer technology, low computer time and the possibility of complete automation of design and research procedures in solving theoretical and practical tasks related to increasing energy performance and quality of electrical energy in power supply systems.
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Ягуп, Катерина Валеріївна. "Покращання енергетичних показників електротехнічних систем із застосуванням пошукової оптимізації на комп'ютерних моделях." Thesis, Харківський національний університет міського господарства ім. О. М. Бекетова, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/35543.

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Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.09.03 – електротехнічні комплекси та системи. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018. Розглядаються методи оптимізації режимів систем електропостачання з несиметричними і нелінійними навантаженнями з метою підвищення енергетичних показників і розрахунку симетро-компенсуючих пристроїв. Обґрунтовано необхідність і можливість застосування комп'ютерних засобів, розроблено узагальнені алгоритми реалізації пошукової оптимізації. Розроблені методи успішно застосовані для оптимізації режимів в трипровідних і чотирипровідних системах, в тому числі в системах з взаємно-зв'язаними індуктивностями, в системах залізничного електропостачання, в системі з нейтралером, в системах живлення асинхронних двигунів, освітлювальних приладів високого тиску, в системах з силовими активними фільтрами, а також для випадків кількох навантажень з урахуванням вкладу кожного з них в зниження енергетичних показників системи.
Thesis for a Doctor’s degree in Engineering Science by specialty 05.09.03 – Electrical Engineering Complexes and Systems. – National Technical University "Kharkov Polytechnic Institute", Kharkiv, 2018. The dissertation is devoted to the development and research of optimization methods of power supply systems modes in electrotechnical systems with asymmetric and nonlinear loads in order to increase the energy indices and calculate the parameters of symmetry-compensating devices using mathematical and computer models, and using search engine optimization implemented with the use of modern software of computer mathematics. The necessity and the possibility of using computer tools for solving set tasks are substantiated. The generalized algorithms for implementing search engine optimization using modern software packages are developed. The possibilities of applying different optimization criteria for solving the problems of increasing the energy indices of power supply systems with asymmetric and nonlinear loads are shown. The properties of the search engine optimization system have been found to extrude the inappropriate element of the synthesized device, as well as the possibility of releasing the optimization variables by increasing their amount, which allows us to get ahead of a faster locating of the local minimum and then recalculate the parameters corresponding to the global minimum are shown. The developed method of search optimization using the models of power supply systems has been successfully applied for optimization of regimes and synthesis of symmetry-compensating devices in three-phase three-wire and four-wire systems of power supply. The possibilities of using the optimization tools for Mathcad and Matlab software packages are considered, in particular, using zero-order methods that do not require the calculation of derivatives, such as the deformed polyhedron method and the conjugate gradient method. The algorithm of load equivalence is proposed, with the help of which the symmetrical and asymmetric parts of the load are allocated. After this, the parameters of the balancing device are determined with sufficient accuracy by means of the Steinmetz and Kennely formulas. The method of currents direct symmetric component rotation with the preservation of symmetry and the mode of full reactive power compensation is proposed. For four-wire systems, the use of a generalized reactive element in a symmetry-compensating device is proposed, which accelerates the process of achieving the optimal solution. The method of determining the optimal mode based on the decomposition of the power supply system, which improves the convergence of the solution processes, is developed. Systems of power supply containing inductively coupled elements are considered. The calculation of the symmetry-compensating device of the traction system of the alternating current railway power supply is considered. A four-wire system with a neutralizer was studied, with the help of search engine optimization the parameters of the symmetry-compensating device were determined which allows to balance and counterbalance such a system. The possibilities of optimization of the regime in the power system of asynchronous motors, including the asymmetry of the supply network, are shown. Compensation of reactive power allows here to reduce the consumed currents and increase the efficiency of the system. To find the optimal modes of systems with an arc discharge, visual models have been developed that are adapted for use with the SimPowerSystem library elements. With the help of these models, the possibilities of increasing the power indices of arc discharge power supply systems, including high-pressure lighting devices, are investigated. It was shown that the optimization of the power factor alone, calculated with the help of the pro-posed methods, leads to decrease in the current consumed by the fundamental harmonic, which substantially reduces the losses in the transmission lines. For a thyristor compensator with single-stage switching, the advantage of symmetric control is proven, which greatly improves the spectrum of harmonics of supply currents. The use of the search optimization method to increase the power factor is shown without the use of traditional rather complicated control systems by power active filters. Comparison signals are used as control signals, synchronized with the phase voltages of the supply system. The amplitudes of these signals are accepted as optimization variables, and the optimization criterion is determined by the balance of active power in the system, which is characterized by the stabilization of the periodic voltage on the storage capacitor of the power active filter. The problems of synthesis of symmetric-compensating devices for several asymmet-rical loads in parallel and cascade connection are considered. The task is to determine the parameters of the symmetric-compensating devices for each of the loads separately, and the contribution to the creation of asymmetry and the generation of reactive power of each connected load must be taken into account. This problem is solved by the method of search optimization, and it is shown that, in forming the objective function, currents in the feeders, supplying energy from the point of connection of the load to the network to the common point of connection of the load and the symmetric-compensating device. It is effective to use the developed decomposition method, which makes it possible to simplify and accelerate the determination of the optimal regime of the system under study, taking into account the contribution of each load to the reduction of the energy parameters of the system as a whole. The case is also analyzed when two loads consisting of both unbalanced linear and nonlinear loads are simultaneously connected to the network. Optimization of the regime with increasing power factor is achieved by using a parallel power active filter with control over the proposed optimization algorithm. Methods and algorithms of search optimization developed for the purposes of increasing the energy indicators of power supply systems with asymmetric and nonlinear consumers developed and presented in the thesis work are characterized by high accuracy, the maximum possible use of computer technology, low computer time and the possibility of complete automation of design and research procedures in solving theoretical and practical tasks related to increasing energy performance and quality of electrical energy in power supply systems.
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Fylladitakis, Emmanouil D. "Characterisation of electrohydrodynamic fluid accelerators comprising highly asymmetric high voltage electrode geometries." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13670.

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Electrohydrodynamics (EHD) is a promising research field with several trending applications. Even though the phenomenon was first observed centuries ago, there is very little research until the middle 20th century, as the mechanisms behind it were very poorly understood. To this date, the majority of research is based on the development of empirical models and the presentation of laboratory experiments. This work begins with an extensive literature review on the phenomenon, clarifying conflicts between researchers throughout the history and listing the findings of the latest research. The literature review reveals that there are very few mathematical models describing even the most important parameters of the EHD fluid flow and most are either empirical or greatly simplified. As such, practical mathematical models for the assessment of all primary performance characteristics describing EHD fluid accelerators (Voltage Potential, Electric Field Intensity, Corona Discharge Current and Fluid Velocity) were developed and are begin presented in this work. These cover all configurations where the emitter faces a plane or another identical electrode and has a cylindrical surface. For configurations where the emitter faces a plane or another identical electrode and has a spherical surface, Corona Discharge Current and Fluid Velocity models have been presented as well. Laboratory experiments and computer simulations were performed and are being thoroughly presented in Chapter 4, verifying the accuracy and usability of the developed mathematical models. The laboratory experiments were performed using two of the most popular EHD electrode configurations - wire-plane and needle-grid. Finally, the findings of this research are being summarized in the conclusion, alongside with suggestions for future research. The step-by-step development of the equipotential lines mathematical model is presented in Appendix A. Appendix B covers the mathematical proof that the proposed field lines model is accurate and that the arcs are perpendicular to the surface of the electrodes and to all of the equipotential lines.
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Tong, Sai-kit. "A computer-aided measurement system for monopolar high-voltage direct-current coronating lines /." [Hong Kong] : University of Hong Kong, 1986. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12321771.

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Zhang, Di. "Analysis and Design of Paralleled Three-Phase Voltage Source Converters with Interleaving." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/27579.

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Three-phase voltage source converters(VSCs) have become the converter of choice in many ac medium and high power applications due to their many advantages, including low harmonics, high power factor, and high efficiency. Modular VSCs have also been a popular choice as building blocks to achieve even higher power, primarily through converter paralleling. In addition to high power ratings, paralleling converters can also provide system redundancy through the so-called (N+1) configuration for improved availability, as well as allow easy implementation of converter power management. Interleaving can further improve the benefit of paralleling VSCs by reducing system harmonic currents, which potentially can increase system power density. There are many challenges to implement interleaving in paralleled VSCs system due to the complicated relationships in a three-phase power converter system. In addition, to maximize the benefit of interleaving, current knowledge of symmetric interleaving is not enough. More insightful understanding of this PWM technology is necessary before implement interleaving in a real paralleled VSCs system. In this dissertation, a systematic methodology to analyze and design a paralleled three-phase voltage source converters with interleaving is developed. All the analysis and proposed control methods are investigated with the goal of maximizing the benefit of interleaving based on system requirement. The dissertation is divided into five sections. Firstly, a complete analysis studying the impact of interleaving on harmonic currents in ac and dc side passive components for paralleled VSCs is presented. The analysis performed considers the effects of modulation index, pulse-width-modulation (PWM) schemes, interleaving angle and displacement angle. Based on the analysis the method to optimize interleaving angle is proposed. Secondly, the control methods for the common mode (CM) circulating current of paralleled three-phase VSCs with discontinuous space-vector modulation (DPWM) and interleaving are proposed. With the control methods, DPWM and interleaving, which is a desirable combination, but not considered possible, can be implemented together. In addition, the total flux of integrated inter-phase inductor to limit circulating current can be minimized. Thirdly, a 15 kW three phase ac-dc rectifier is built with SiC devices. With the technologies presented in this dissertation, the specific power density can be pushed more than 2kW/lb. Fourthly, the converter system with low switching frequency is studied. Special issues such as beat phenomenon and system unbalance due to non-triplen carrier ratio is explained and solved by control methods. Other than that, an improved asymmetric space vector modulation is proposed, which can significantly reduce output current total harmonic distortion (THD) for single and interleaved VSCs system. Finally, the method to protect a system with paralleled VSCs under the occurrence of internal faults is studied. After the internal fault is detected and isolated, the paralleled VSCs system can continue work. So system reliability can be increased.
Ph. D.
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8

湯世傑 and Sai-kit Tong. "A computer-aided measurement system for monopolar high-voltage direct-current coronating lines." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31207467.

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Smith, Johan. "High voltage direct current strategy solving power delivery shortages to localized area of national grid." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1102.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009
The industrial and population growth of a nation can cause power delivery problems to localized areas of a national grid through their increased demand for electrical energy. One reason for these power shortages is the insufficient current carrying capacity of existing high voltage alternating current, (HVAC), transmission lines supplying the area. High voltage direct current (HVDC) transmission lines are a possible solution as they provide better power delivery than HVAC lines. New or upgraded HVAC lines, or HVDC lines or combinations of HVAC and HVDC lines are possible solutions to improve power delivery. This research investigates the various line possibilities using theory. and cutting edge frequency and time domain software tools. The challenge is how to approach this problem. What methodology or structure should be used? Thus one of the contributions of this work is the development of a strategy (flow chart), for solving power delivery problems to localized areas of a national grid through individual or combinations (e.g. parallel operation) of HVAC and/or HVDC transmission lines. The main contribution is the evaluation of a HVDC system as a solution to overcoming power delivery shortages to a localized area of a national grid. Three different software packages (two industrial and one academic) namely, PSCAD/EMTDC (time domain), DlgSILENT PowerFactory (frequency domain) and MathCAD software are evaluated for their capability to perform the simulation studies necessary to prove the possible solutions given in the developed flow chart. The PSCAD/EMTDC software package is evaluated for integrated HVAC/HVDC load flow analyses, DlgSILENT for individual and parallel combinations of HVAC lines and MathCAD to prove hand calculations to software results. Five case studies are conducted. The first case study demonstrates a healthy system with no delivery shortcomings, the second case study portrays the delivery shortcoming due to increased localized area demand, and the remaining three case studies explore possible solutions to solve the problem. The first possible solution is to construct an identical HVAC line in parallel to the existing line.
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Khan, Asghar. "Torque pulsations and currents in induction motors with unbalanced voltages." Thesis, 1987. http://spectrum.library.concordia.ca/5433/1/ML41653.pdf.

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Books on the topic "Currents and voltages asymmetry"

1

Touch voltages in electrical installations. Oxford, [England]: Blackwell Scientific Publications, 1993.

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Yu, Jian-Guo. Computer analysis of touch voltages and stray currents for DC railways. Birmingham: University ofBirmingham, 1992.

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Aleksandar, Marinčić, ed. Dnevnik istraživanja iz Kolorado Springsa, 1899-1900. Beograd: Zavod za udžbenike i nastavna sredstva, 1996.

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Tesla, Nikola. Colorado Springs notes 1899-1900. Edited by Marinčić Aleksandar and Popović Vojin. Beograd: Zavod za udžbenike i nastavna sredstva, 1999.

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Hull, Richard L. Tesla Coil Builder's Guide to the Colorado Springs Notes of Nikola Tesla. 2nd ed. Twenty First Century Books, 1999.

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Hull, Richard L. Tesla Coil Builder's Guide to the Colorado Springs Notes of Nikola Tesla. Twenty First Century Books, 1994.

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Wright, A. G. Voltage dividers. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199565092.003.0013.

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Voltage dividers provide accelerating voltages to generate multiplier gain. Dynode voltages must remain constant and independent of the light input to maintain stable gain. The standard resistive divider never quite satisfies this requirement, although acceptable performance can be achieved by careful design. The inclusion of zener diodes improves performance but field-effect transistor (FET) circuits can provide gain stability at high mean anode currents, regardless of whether the application is pulsed or analogue. Design procedures for active and semi-active voltage dividers are presented. Dividers based on the Cockcroft–Walton (CW) principle are particularly suited to portable instrumentation because of their low standing current. Consideration is given to pulsed operation, decoupling, switch-on transients, ripple, dynode signals, single cable dividers, and equivalent circuits at high frequencies. Gating is used to protect a photomultiplier, in the presence of high light levels, by reducing the gain electronically. Various methods for gating a voltage divider are presented.
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Anderson, James A. Computing Hardware. Oxford University Press, 2018. http://dx.doi.org/10.1093/acprof:oso/9780199357789.003.0002.

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Chapter 2 presents a kind of computation currently unfamiliar to most, the analog computer. Fifty years ago, they were considered viable competitors to the newer digital computer. Analog computers compute by the use of physical analogs, using, for example, voltages, currents, or shaft positions to represent numbers. They compute using the device properties, not logic. Examples include the balance, a simple device known for millennia; the “Antikythera mechanism,” a complex astronomical calculator from the first century BC; the slide rule; the US Navy’s Mark I fire control computer used for much of the 20th century to aim naval gunfire; and electronic analog computers built in large numbers after World War II. Analog computers can have advantages in ruggedness, simplicity, and reliability but lack the flexibility of digital computers.
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Book chapters on the topic "Currents and voltages asymmetry"

1

Kok, Wim. "Voltages and Currents." In Capillary Electrophoresis: Instrumentation and Operation, 20–23. Wiesbaden: Vieweg+Teubner Verlag, 2000. http://dx.doi.org/10.1007/978-3-322-83133-0_4.

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Bird, John. "Alternating voltages and currents." In Bird's Electrical and Electronic Principles and Technology, 308–32. 7th ed. London: Routledge, 2021. http://dx.doi.org/10.1201/9781003130406-19.

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Bird, John. "Alternating voltages and currents." In Bird's Electrical Circuit Theory and Technology, 260–80. 7th ed. London: Routledge, 2021. http://dx.doi.org/10.1201/9781003130338-19.

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Schon, Klaus. "High Alternating Voltages and Currents." In High Voltage Measurement Techniques, 7–42. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-21770-9_2.

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Schon, Klaus. "High Direct Voltages and Currents." In High Voltage Measurement Techniques, 43–77. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-21770-9_3.

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Zemanian, Armen H. "Hyperreal Currents and Voltages in Transfinite Networks." In Graphs and Networks, 99–131. Boston, MA: Birkhäuser Boston, 2004. http://dx.doi.org/10.1007/978-0-8176-8178-4_6.

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Gonschorek, Karl-Heinz, and Ralf Vick. "Thinking in Voltages, Currents, Fields and Impedances." In Electromagnetic Compatibility for Device Design and System Integration, 7–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03290-5_2.

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Schon, Klaus. "Characterisation and Generation of High Impulse Voltages and Currents." In High Impulse Voltage and Current Measurement Techniques, 5–38. Heidelberg: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00378-8_2.

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Kitcher, Christopher. "Waveform and Phasor Representation of Alternating Currents and Voltages." In Electrical Installation Calculations, 51–62. 9th ed. London: Routledge, 2022. http://dx.doi.org/10.1201/9781003258728-6.

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Boguslawsky, Iliya, Nikolay Korovkin, and Masashi Hayakawa. "Investigation Methods of Currents Distribution in Squirrel Cages with Asymmetry." In Large A.C. Machines, 203–17. Tokyo: Springer Japan, 2016. http://dx.doi.org/10.1007/978-4-431-56475-1_10.

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Conference papers on the topic "Currents and voltages asymmetry"

1

Popa, Gabriel Nicolae, Corina Maria Dinis, Sorin Ioan Deaconu, and Iosif Popa. "On Currents Asymmetry Protection For Three Phase Low Voltage Induction Motors." In 2018 International Conference on Applied and Theoretical Electricity (ICATE). IEEE, 2018. http://dx.doi.org/10.1109/icate.2018.8551429.

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Lewis, W. P. "The calculation of fault currents and voltages." In IEE Colloquium on Fault Level Assessment - Guessing with Greater Precision? IEE, 1996. http://dx.doi.org/10.1049/ic:19960078.

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Katayama, Takuya, Takeki Ogitsu, Hikaru Kokumai, Hiroshi Takemura, Tomohiro Nakayama, and Hiroshi Mizoguchi. "Study on effect of neutral voltages on shaft voltages causing bearing currents." In IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2013. http://dx.doi.org/10.1109/iecon.2013.6699892.

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Czarnecki, Leszek S. "Currents' Physical Components (CPC) in systems with semi-periodic voltages and currents." In 2015 International School on Nonsinusoidal Currents and Compensation (ISNCC). IEEE, 2015. http://dx.doi.org/10.1109/isncc.2015.7174722.

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Luiz, A. S. A., and B. J. Cardoso Filho. "Sinusoidal voltages and currents in high power converters." In IECON 2008 - 34th Annual Conference of IEEE Industrial Electronics Society. IEEE, 2008. http://dx.doi.org/10.1109/iecon.2008.4758491.

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Jones, C. C. R., D. Rowse, G. A. M. Odam, and C. Pinchen. "Non-Linear Effects Influencing Lightning Induced Currents and Voltages." In International Conference on Lightning and Static Electricity. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2001. http://dx.doi.org/10.4271/2001-01-2930.

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Das, Ratul, Janko Celikovic, Siamak Abedinpour, Mark Mercer, Dragan Maksimovic, and Hanh-Phuc Le. "Demystifying Capacitor Voltages and Inductor Currents in Hybrid Converters." In 2019 20th Workshop on Control and Modeling for Power Electronics (COMPEL). IEEE, 2019. http://dx.doi.org/10.1109/compel.2019.8769722.

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Quax, Guido, and Theo Smedes. "Latchup holding voltages and trigger currents in an SOI technology." In 2016 IEEE International Reliability Physics Symposium (IRPS). IEEE, 2016. http://dx.doi.org/10.1109/irps.2016.7574559.

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Vinnal, Toomas, Lauri Kutt, and Marek Jarkovoi. "harmonic Currents and Voltages in Industrial LV Networks - Case Studies." In 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM). IEEE, 2018. http://dx.doi.org/10.1109/speedam.2018.8445234.

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Grcev, L. "Computation of transient voltages near complex caused by ligntning currents." In International Symposium on Electromagnetic Compatibility. IEEE, 1992. http://dx.doi.org/10.1109/isemc.1992.626123.

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Reports on the topic "Currents and voltages asymmetry"

1

Johnson, William Arthur, Larry Kevin Warne, Kimball O. Merewether, and Kenneth C. Chen. Joint voltages resulting from lightning currents. Office of Scientific and Technical Information (OSTI), March 2007. http://dx.doi.org/10.2172/902220.

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Dinallo, M. S., and R. J. Fisher. Voltages across assembly joints due to direct-strike lightning currents. Office of Scientific and Technical Information (OSTI), August 1994. http://dx.doi.org/10.2172/10190346.

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Schnetzer, G. H., and R. J. Fisher. Measured voltages and currents internal to closed metal cylinders due to diffusion of simulated lightning currents. Office of Scientific and Technical Information (OSTI), August 1994. http://dx.doi.org/10.2172/10181980.

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