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    Wyświetlanie 1-39 z 39
    Tytuł:
    Effect of Hydraulic Characteristics on Fluid Transients Analysis under Different Types of Control Valves
    Autorzy:
    Al-Zaidi, Basim M.
    Ismaeel, Abaas J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2202314.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    hydraulic characteristics
    fluid transients
    valve
    Opis:
    In this study, several types of valves were used to study the impact of the valves types and closure characteristics on fluid transients. The valve closure curves, which are the variation of the effective valve opening as a function of percentage opening area, were derived for different selected valves. Six different types of valves were selected to study the effect of the valves types on fluid transient conditions. For simplification, a very simple pipeline system was assumed and presented in this study. The system is about two pipes connected in a series junction and they take the water from a constant-level reservoir at upstream and a valve at downstream. The duration of valve closure was taken as six seconds which plays an important role in the pressure development in the system. A method of characteristics is applied to compute the transient conditions under gradual closure of the valves. Valve data of various forms were compiled and reported as discharge and headloss coefficients as a function of valve opening. The effect of valve geometry and operation on the relative valve opening were compared. Discharge and headloss coefficients were also compared between valve types. The study concluded that transient conditions depend on the valve type. The comparison between the results of all valve types indicated that the changes in pressure and discharges depend on valve type where there is a difference in effective valve opening. It can be concluded that the valve with the highest value of valve effective opening has less effect on transient conditions, i.e., the faster changes of effective valve opening the larger the effect on transient conditions (discharge and the greater the magnitude of the pressure wave). This study would help to select the property valve in pipeline design.
    Źródło:
    Journal of Ecological Engineering; 2022, 23, 12; 111--123
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The modeling of centrifugal pump transients
    Autorzy:
    Szymczyk, J.
    Karaśkiewicz, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/175255.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    rotodynamic pumps
    complete pump characteristics
    transients
    Opis:
    Centrifugal pumps are part of larger hydraulic systems. These hydraulic machines can work not only in the pumping mode but in a number of other modes whose job description is possible using complete characteristics. Some of these modes, such as the turbine mode and the reversed turbine mode, may have practical significance. Knowledge of the transition from one steady state to another state allows to estimate instantaneous values such as, e.g., flow current and torque, which may be even a few times higher than nominal. The principal issues in these transients are amplitudes of parameters of these pumps and the time constants associated with the characteristics of the system.
    Źródło:
    Transactions of the Institute of Fluid-Flow Machinery; 2015, 130; 83-92
    0079-3205
    Pojawia się w:
    Transactions of the Institute of Fluid-Flow Machinery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Output characteristics of step-down (Buck) power converter
    Autorzy:
    Janke, W.
    Bączek, M.
    Walczak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/201669.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    DC-DC converters
    output characteristics
    load transients
    Opis:
    The output characteristics of switched-mode dc-dc buck power converter are discussed. The shape of output characteristics is especially important for converters used for supplying modern processors. An output impedance is usually used for description of output characteristics. Many efforts are described in the literature to obtain the satisfastory features of closed-loop output impedance. Another approach, presented in the paper, is based on the concept of the output voltage response corresponding to the load conductance change, and is expressed by hr transmittance. Simulations of output characteristics of the buck converter in frequency and in time-domain have been performed for the ideal case as well as for a more realistic situation, with the parasitic resistances of converter elements included. The measurement results differ substantially from characteristics calculated for an ideal converter and are in good consistency with simulations including parasitics.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 4; 751-755
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of transformer modeling on riser pole arresters behavior during switching transients
    Autorzy:
    Abbaszadeh, A.
    Abedi, M.
    Doustmohammadi, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/140474.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    arresters
    ATP software
    ferroresonance
    transformer
    power system transients
    Opis:
    Arresters are widely used in power systems to protect other equipment against overvoltages. However, in some conditions, they can’t operate successfully. One of the disturbances leading to the failure of the riser pole arresters is the ferroresonance overvoltages. In this paper, at first the influence of different transformer simulation models of ATP software on the occurrence of ferroresonance is studied and then the effect of ferroresonance on the riser pole arrester has been scrutinized through the thermal and electrical performance of the arrester in an underground distribution system. The results show that the arrester temperature rises due to energy dissipation in a ferroresonance circumstance, which indeed may result into the explosion of the arrester. Also, applying different models of the transformer in the ATP software and comparing the results, it is shown that the available models do not show the same effect on the arrester.
    Źródło:
    Archives of Electrical Engineering; 2017, 66, 4; 717-730
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improved method for simulating transients of turbulent pipe flow
    Autorzy:
    Zarzycki, Z.
    Kudźma, S.
    Urbanowicz, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/280935.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    unsteady pipe flow
    transients
    waterhammer
    efficient numerical simulation
    Opis:
    The paper presents the problem of modelling and simulation of transients during turbulent fluid flow in hydraulic pipes. The instantaneous wall shear stress on a pipe wall is presented in the form of integral convolution of a weighting function and local acceleration of the liquid. This weighting function depends on the dimensionless time and Reynolds number. Its original, very complicated mathematical structure is approximated to a simpler form which is useful for practical engineering calculations. The paper presents an efficient way to solve the integral convolution based on the method given by Trikha (1975) for laminar flow. An application of an improved method with the use of the Method of Characteristic for the case of unsteady flow (water hammer) is presented. This method is characterised by high efficiency compared to traditional numerical schemes.
    Artykuł przedstawia zagadnienie modelowania i symulacji przebiegów przejściowych podczas turbulentnego przepływu cieczy w przewodach ciśnieniowych. Chwilowe naprężenie styczne na ściance przewodu przedstawiono w postaci całki splotowej z funkcji wagi i przyspieszenia cieczy. Funkcja wagi dla naprężenia stycznego na ściance przewodu zależy od czasu bezwymiarowego i liczby Reynoldsa. Ma ona zawiłą postać matematyczną, dlatego aproksymowano ją do prostszej postaci, przydatnej do praktycznych obliczeń inżynierskich. Przedstawiono efektywny sposób rozwiązania całki splotowej, opierając się na metodzie podanej przez Trikha (1975) dla przepływu laminarnego. Podano zastosowanie ulepszonej metody symulacji naprężenia stycznego do metody charakterystyk podczas uderzenia hydraulicznego. Charakteryzuje się ona dużą efektywnością w stosunku do metody tradycyjnej.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2011, 49, 1; 135-158
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Technical solutions for the control and command system of a Plasma Focus device
    Autorzy:
    Martin, D. I.
    Zoita, V. I.
    Cotruta, D. A.
    Jianu, A. V.
    Ighigeanu, D. I.
    Bestea, V. I.
    Powiązania:
    https://bibliotekanauki.pl/articles/147621.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    control system
    electromagnetic transients
    galvanic separation
    plasma focus
    Opis:
    The paper presents the technical problems related to the electrical control and command system (ECC system) for the plasma focus installation IPF-4/5A having the following main parameters: 1 MA plasma current and 40 kJ energy stored at 20 kV charging voltage. The ECC system applies 23 interlocked logical commands, acquires and processes 28 logical states, acquires, processes and displays continuously the main slow-varying signals coming from IPF-4/5A subassemblies. All the plasma focus installation operational sequences are governed by strict hard and soft interlocking using in parallel two control and command systems: one based on PC-control methods and another based on classical control techniques.
    Źródło:
    Nukleonika; 2001, 46, suppl. 1; 89-91
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transient recovery voltage analysis for various current breaking mathematical models: shunt reactor and capacitor bank de-energization study
    Autorzy:
    Oramus, P.
    Chmielewski, T.
    Kuczek, T.
    Piasecki, W.
    Szewczyk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/140943.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    arc modelling
    overvoltages studies
    EMTP-ATP program
    transients analysis
    Opis:
    Electric arc is a complex phenomenon occurring during the current interruption process in the power system. Therefore performing digital simulations is often necessary to analyse transient conditions in power system during switching operations. This paper deals with the electric arc modelling and its implementation in simulation software for transient analyses during switching conditions in power system. Cassie, Cassie-Mayr as well as Schwarz-Avdonin equations describing the behaviour of the electric arc during the current interruption process have been implemented in EMTP-ATP simulation software and presented in this paper. The models developed have been used for transient simulations to analyse impact of the particular model and its parameters on Transient Recovery Voltage in different switching scenarios: during shunt reactor switching-off as well as during capacitor bank current switching-off. The selected simulation cases represent typical practical scenarios for inductive and capacitive currents breaking, respectively.
    Źródło:
    Archives of Electrical Engineering; 2015, 64, 3; 441-458
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation on ferroresonance due to power transformer energization in high voltage 400 kV transmission grid
    Autorzy:
    Polewaczyk, Mateusz
    Robak, Sylwester
    Szewczyk, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/141509.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ferroresonance
    high voltage
    Poincaré map
    power system transients
    PSCAD
    Opis:
    This paper presents a study on ferroresonance occurring in a high voltage 400 kV transmission grid due to energization of power transformer under no-load conditions. The system scenarios analyzed in the present paper are considered as critical for development and modernization plans as currently announced by the national grid operator in Poland. The PSCAD simulation model was developed and applied for several study cases of a system with double-circuit arrangement of a transmission line. It is shown that the ferroresonant oscillations can be initiated by two-phase switching operation of a line circuit breaker. The impact of the double-circuit length on the ferroresonance mode and severity is demonstrated with the use of the Poincaré map analysis and Short Time Fourier Transform. It is demonstrated that the length of the transmission line that is mutually coupled in the double-circuit arrangement has a significant impact on the ferroresonance occurrence and on its mode. As the ferroresonance can pose severe threat to the power system components due to the severe overvoltage and overcurrent oscillations, the analysis presented in this paper demonstrates the necessity of the ferroresonance analyses for any re-designed transmission system.
    Źródło:
    Archives of Electrical Engineering; 2019, 68, 4; 771-786
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling transients in MV resonantly grounded industrial grid during single line to ground faults
    Autorzy:
    Warecki, Jurij
    Gajdzica, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/377060.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
    Tematy:
    electrical grid
    grounding methods
    transients overvoltage
    transient intermittent faults
    Opis:
    Medium voltage distribution power grids mostly operate with ungrounded neutral points of transformer. The philosophy about these power supply systems based on the assumption that the electrical grid is more reliable. However the practice of operation showed that currents of single phase or multiple faults to ground depend mostly on the earth capacitances of cables connected to power grid and configuration and structure in relation to the main substation buses. Moreover, this kind of arcing ground faults on the ungrounded system causes transient overvoltages several times than nominal value. In the consequence, it may be dangerous for the electrical devices connected to the power system. The article focuses on the transient impact the equipment insulation due to faults in the middle voltage industrial grid with adjustable speed drives. The examination results of transient voltages across the system was presented. The Matlab/ Simulink Software was used to modeling system behavior during intermittent faults.
    Źródło:
    Poznan University of Technology Academic Journals. Electrical Engineering; 2019, 98; 65-75
    1897-0737
    Pojawia się w:
    Poznan University of Technology Academic Journals. Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Control of operability of Peltier modules in cooling systems based on the analysis of transient operating modes
    Autorzy:
    Kuzichkin, Oleg Rudolfovich
    Konstantinov, Igor Sergeevich
    Vasilyev, Gleb Sergeevich
    Surzhik, Dmitry Igorevich
    Powiązania:
    https://bibliotekanauki.pl/articles/1845461.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermoelectric system
    agriculture
    complex
    transients
    peltier effect
    identification algorithms
    Opis:
    The paper is devoted to the control of operability of Peltier modules based on the analysis of transient modes of their operation. Advantages of using low-power thermoelectric modules for the development of thermoelectric plants with adaptive control systems for the needs of the agricultural complex, which significantly reduce their cost characteristics, are shown. The problem of using the stationary mode of their operation, associated with the low efficiency of the modules, as well as the dynamic mode, associated with the presence of transient processes, is indicated. It is noted that overcoming this problem requires solution of the task of automation of reliability providing the well-known approaches to its solution are shown, for which the key advantages and disadvantages are given. An approach is proposed to complex control of the operability and quality of thermoelectric modules during their expluatation in three components of the physical process of thermoelectric conversion (Peltier thermoelectric effect, electrical and thermal transfer phenomena) by analyzing transients in the system based on identification algorithms. To justify it, the necessary equations and mathematical relations are given. Aprobating of the proposed approach was carried out experimentally by determining the time constants for operable and defective commercially available modules and showed its significant advantages over the standard verification procedure.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 2; 31-42
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Rho-associated kinase inhibition on actin cytoskeleton structure and calcium response in glioma C6 cells
    Autorzy:
    Targos, Berenika
    Pomorski, Paweł
    Krzemiński, Patryk
    Barańska, Jolanta
    Rędowicz, Maria
    Kłopocka, Wanda
    Powiązania:
    https://bibliotekanauki.pl/articles/1041182.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    glioma C6
    actin cytoskeleton
    RhoA
    ROCK
    calcium transients
    Opis:
    The role of actin cytoskeleton functional state in glioma C6 cell morphology and calcium signaling was investigated through modification of myosin II activity by blocking Rho-associated kinase with the specific inhibitor Y-27632. Treatment of glioma C6 cells with ROCK inhibitor resulted in actin cytoskeleton reorganization and also in the changed shape and distribution of mitochondria. Changes in the distribution of ER, the main calcium store in glioma C6 cells, were not visible. The inhibition of myosin II activity influences the first phase of calcium signaling evoked by agonist, and both phases of thapsigargin-evoked calcium response. We suggest that the observed increase in Ca2+ release from intracellular stores induced by IP3 formation as well as inhibition of SERCA ATPase is at least in part related to severely affected mitochondria. Enhancement of capacitative calcium entry evoked by thapsigargin is probably associated with the reorganization of the acto-myosin II system. ATP-induced calcium response presents no changes in the second phase. We observed that ATP stimulation of Y-27632 pretreated cells leads to immediate morphological rearrangement of glioma C6 cells. It is a consequence of actin cytoskeleton reorganization: formation of stress fibers and relocation of phosphorylated myosin II to actin filaments. It seems that the agonist-evoked strong calcium signal may be sufficient for myosin II activation and the stress fiber organization. This is the first work showing the dependence between the functional state of the acto-myosin II system and calcium signaling stressing the reversible character of this relationship.
    Źródło:
    Acta Biochimica Polonica; 2006, 53, 4; 825-831
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 2: Small Normalised Voltage Command
    Autorzy:
    Reznikov, Boris
    Ruderman, Alex
    Galanina, Valentina
    Powiązania:
    https://bibliotekanauki.pl/articles/1193863.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    4-level DC–DC converter
    flying capacitor
    natural balancing
    transients
    Opis:
    A 4-level flying capacitor converter (FCC) operation is considered on a base of discrete state-space model. A transition matrix is obtained for a pulse width modulation (PWM) period for small normalised voltage command values [0, 1/3]. The transition matrix elements are expanded into power series by small parameters. The matrix eigenvalues are presented in the form of power series as well. Six separate transients are constructed for six possible initial FCC states on a PWM period. Inductor current and capacitors’ voltage transients are found for the voltage source power-up as the arithmetic average of the six separate transients. Finally, the discrete solutions are replaced by equivalent continuous ones. Simple and accurate formulas for inductor current and capacitors’ voltage transients demonstrate good agreement with simulation results.
    Źródło:
    Power Electronics and Drives; 2020, 5, 40; 41-57
    2451-0262
    2543-4292
    Pojawia się w:
    Power Electronics and Drives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 1: Large Normalised Voltage Command
    Autorzy:
    Reznikov, Boris
    Ruderman, Alex
    Galanina, Valentina
    Powiązania:
    https://bibliotekanauki.pl/articles/1193906.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    4-level DC-DC converter
    flying capacitor
    natural balancing
    transients
    Opis:
    A 4-level flying capacitor converter (FCC) operation is considered on a base of discrete state-space model. A transition matrix is obtained for a pulse width modulation (PWM) period for large normalised voltage command values [1/3, 1). The transition matrix elements are expanded into power series by small parameters. The matrix eigenvalues are presented in the form of power series as well. Six separate transients are constructed for six possible initial FCC states on a PWM period. Inductor current and capacitors’ voltage transients are found for the voltage source power-up as the arithmetic average of the six separate transients. Finally, the discrete solutions are replaced by equivalent continuous ones. Simple and accurate formulas for inductor current and capacitors’ voltage transients demonstrate good agreement with simulation results.
    Źródło:
    Power Electronics and Drives; 2020, 5, 40; 27-40
    2451-0262
    2543-4292
    Pojawia się w:
    Power Electronics and Drives
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vibration transients of reservoir-pipe-valve system caused by water hammer
    Autorzy:
    Miao, Yang
    Jiang, Yuncheng
    Qiu, Zaihui
    Pan, Jun
    Wang, Lu
    Han, Zhenrong
    Li, Kun
    Zhang, Li
    Zhang, Xiaolu
    Powiązania:
    https://bibliotekanauki.pl/articles/1839616.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    reservoir-pipe-valve system (RPV system)
    water hammer
    vibration
    transients
    Opis:
    A severe oscillation, accompanied with an abnormal “click” sound, of a fuel feeding pipe system during valve closing, when the feeding flowrate reaches a certain value, is observed experimentally. A fluctuation model in which stiffness and damping coefficients of the vibration system are time varying is proposed. Each coefficient is composed of two parts, one of which is constant and the other is time varying. Based on this model, simulation transients of the vibration displacement, velocity and pressure in the pipe are presented. Simulations of the pressure transients are compared with experimental data detected by pressure transducer, which shows that both have fluctuations in the transient process at a large flowrate.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2020, 58, 4; 1037-1048
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of the stator inductances of the expanded Park model and an approach on parameter identification using the evolution strategy
    Autorzy:
    Schmuelling, Ch.
    Kreischer, Ch.
    Gołebiowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/141147.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    evolution strategy
    FEM
    Park equations
    Park theory
    synchronous machines
    transients
    Opis:
    Commonly, the Park model is used to calculate transients or steady-state operations of synchronous machines. The expanded Park theory derives the Park equations from the phase-domain model of the synchronous machine by the use of transformations. Thereby, several hypothesis are made, which are under investigation in this article in respect to the main inductances of two different types of synchronous machines. It is shown, that the derivation of the Park equations from the phase-domain model does not lead to constant inductances, as it is usually assumed for these equations. Nevertheless the Park model is the most common analytic model of synchronous machines. Therefore, in the second part of this article a method using the evolution strategy is shown to obtain the parameters of the Park model.
    Źródło:
    Archives of Electrical Engineering; 2016, 65, 3; 585-599
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of different methods for excitation of synchronous machines
    Autorzy:
    Schmuelling, S.
    Kreischer, Ch.
    Gołȩbiowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1367718.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
    Tematy:
    AC machines
    Brushless machines
    Electromagnetic transients
    Excitation system
    Power system simulation
    Opis:
    The energy turnaround in Germany leads to new operating conditions for small and medium synchronous generators. Since the electricity generation through renewable energy sources, such as wind or photovoltaic, is highly volatile, generators have to run up from standstill into rated operation within several minutes. Hence, it is necessary to compensate a lack of electricity generation caused by wrong weather forecasts. Usually, gas turbine systems provide this possibility. The generator is used as a starter engine due to the connection to a frequency inverter. The excitation current is often provided by static excitation systems. Thus, it is possible to start from standstill and run up the drive until the gas turbine is able to generate a positive torque. A new excitation concept, based on an induction machine with a 3-phase rotor winding, is able to provide an excitation current at 0 rpm and eliminates the need for brushes. To verify the applicability for power systems, both systems are compared under different aspects. The control of the excitation current at different speeds and the possibility to settle shaft oscillations after electrical faults are aspects researched in the paper at hand. A power system simulation is performed with a synchronous machine connected to a grid. Both excitation systems are modeled by equivalent circuit diagrams in Matlab Simscape.
    Źródło:
    Maszyny Elektryczne: zeszyty problemowe; 2015, 3, 107; 89-93
    0239-3646
    2084-5618
    Pojawia się w:
    Maszyny Elektryczne: zeszyty problemowe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Accidents of loss of flow for the ETTR-2 reactor: deterministic analysis
    Autorzy:
    El-Messiry, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/146728.pdf
    Data publikacji:
    2000
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    design base accidents
    LOFA
    loss of flow
    pump coastdown
    reactor transients
    Opis:
    The main objective for reactor safety is to keep the fuel in a thermally safe condition with adequate safety margins during all operational modes (normal-abnormal and accidental states). To achieve this purpose an accident analysis of different design base accident (DBA) as loss of flow accident (LOFA), is required for assessing reactor safety. The present work concerns this transients applied to Egypt Test and Research Reactor ETRR-2 (new reactor). An accident analysis code FLOWTR is developed to investigate the thermal behaviour of the core during such flow transients. The active core is simulated by two channels: 1 - hot channel (HC), and 2 - average channel (AC) representing the remainder of the core. Each channel is divided into four axial sections. The external loop, core plene, and core chimney are simulated by different dynamic lumps. The code includes modules for pump coast down, flow regimes, decay heat, temperature distributions, and feedback coefficients. FLOWTR is verified against results from RETRAN code, THERMIC code and commissioning tests for null transient case. The comparison shows a good agreement. The study indicates that for LOFA transients, provided the scram system is available, the core is shutdown safely by low flow signal (496.6 kg/s) at 1.4 s where the HC temperature reaches the maximum value of 45.64°C after shutdown. On the other hand, if the scram system is unavailable, and at t=47.33 s, the core flow decreases to 67.41 kg/s, the HC temperature increases to 164.02°C, and the HC clad surface heat flux exceeds its critical value of 400.00 W/cm2 resulting from the fuel burnout.
    Źródło:
    Nukleonika; 2000, 45, 4; 229-233
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A new closed loop speed control strategy for a vector controlled three-phase induction motor drive
    Autorzy:
    Tripathi, A.
    Dey, A.
    Dwivedi, B.
    Singh, B.
    Chandra, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/262777.pdf
    Data publikacji:
    2008
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    space vector modulation
    VSI
    induction motor model
    transients
    steady state value
    Opis:
    This paper presents a completely mathematical equations based model on control of torque and speed of a three-phase indirect vector controlled VSI fed cage induction motor drive that is controlled through the space vector modulated method. This enables a wide range of acceptability of the model for various values of load and for various types and ratings of induction motors. The uniqueness of the model lies in the fact that the deviations in the torque and speed on sudden application of reference step change in speed values are minimum i.e. when any sudden change in the speed reference is desired, the speed and torque waveforms reveal that the time taken in coming back to their final steady state values is very less and the motor overcomes the perturbation with negligible transients. The same is verified through the simulated results.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2008, 14, 1; 67-72
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Interaction Between Theory, Experiments, and Simulation in Developing Practical Learning Control Algorithms
    Autorzy:
    Longman, R. W.
    Powiązania:
    https://bibliotekanauki.pl/articles/908249.pdf
    Data publikacji:
    2003
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    automatyka
    robotyka
    iterative learning control
    ILC
    2D systems
    learning transients
    Opis:
    Iterative learning control (ILC) develops controllers that iteratively adjust the command to a feedback control system in order to converge to zero tracking error following a specific desired trajectory. Unlike optimal control and other control methods, the iterations are made using the real world in place of a computer model. If desired, the learning process can be conducted both in the time domain during each iteration and in repetitions, making ILC a 2D system. Because ILC iterates with the real world, and aims for zero error, the field pushes the limits of theory, modeling, and simulation, to predict the behavior when applied in the real world. It is the thesis of this paper that in order to make significant progress in this field it is essential that the research effort employ a coordinated simultaneous synergistic effort involving theory, experiments, and serious simulations. Otherwise, one very easily expends effort on something that seems fundamental from the theoretical perspective, but in fact has very little relevance to the performance in real world applications.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2003, 13, 1; 101-111
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulation of transient flows in a hydraulic system with a long liquid line
    Symulacja przepływów przejściowych w układzie hydraulicznym z hydrauliczną linią długą
    Autorzy:
    Zarzycki, Z.
    Kudźma, S.
    Kudźma, Z.
    Stosiak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/281500.pdf
    Data publikacji:
    2007
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    układy hydrauliczne
    pulsacje pomp
    uderzenia hydrauliczne
    unsteady pipe flow
    transients
    pulsation of pump
    Opis:
    The paper presents the problem of modelling and simulation of transients phenomena in hydraulic systems with long liquid lines. The unsteady resistance model is used to describe the unsteady liquid pipe flow. The wall shear stress at the pipe wall is expressed by means of the convolution of acceleration and a weighting function which depends on the (laminar or turbulent) character of the flow. The results of numerical simulation are presented for the waterhammer effect, which is caused by a sudden shift of the hydraulic directional control valve. The following cases of the system supply are considered: the first, with a constant delivery rate of the pump and the second, which additionally considers pulsation of the delivery of the pump. Computer simulations are compared with results of experiments. They are found to be very consistent in the case with the variable rate of the pump delivery taken into accent.
    Artykuł przedstawia zagadnienie modelowania i symulacji zjawisk przejściowych w układach hydraulicznych z hydrauliczną linią długą. Wykorzystano model tarcia niestacjonarnego do opisu niestacjonarnego przepływu w przewodzie. Naprężenia ścinające na ściankach przewodów są określone za pomocą przyspieszenia i finkcji wagi, która zależy od charakteru przepływu (uwarstwiony, turbulentny). Rezultaty symulacji numerycznych są prezentowane dla uderzenia hydraulicznego, które spowodowane jest poprzez nagłe przesterowanie rozdzielacza. Rozpatrywane są dwa przypadki: pierwszy - gdy układ zasilający podaje stałą wartość natężenia przepływu, drugi uwzględniający pulsację wydajności pompy wyporowej. Symulacje komputerowe są porównane z wynikami badań eksperymentalnych. Wykazano dużą zgodność symulacji komputerowych uwzględniających pulsację wydajności pompy z wynikami eksperymentu.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2007, 45, 4; 853-871
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical criterion for the duration of non-chaotic transients in ODEs
    Autorzy:
    Szczebiot, Ryszard
    Kaczyński, Roman
    Gołdyn, Leszek
    Powiązania:
    https://bibliotekanauki.pl/articles/2204683.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    numerical criterion
    non-chaotic transients
    limit cycle
    ODEs systems
    Van der Pol oscillator
    Opis:
    The paper proposes an original numerical criterion for the duration analysis of non-chaotic transients based on the Euclidean norm of a properly defined vector. For this purpose, transient trajectories, prior to their entering a small neighbourhood of the limit cycle, are used. The vector has been defined with its components constituting the lengths of the sections, which connect the origin of the coordinate system with appropriately determined transient trajectory points. The norm of the vector for the analysis of non-chaotic transients has also been applied. As an assessment criterion of transients, the convergence of the norm to small neighbourhood of the limit cycle with the assumed accuracy is used. The paper also provides examples of the application of this criterion to the Van der Pol oscillators in the case of periodic oscillations.
    Źródło:
    Acta Mechanica et Automatica; 2022, 16, 4; 388--392
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hydraulic transients analysis in pipe networks by the method of characteristics (MOC)
    Autorzy:
    Wichowski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/240954.pdf
    Data publikacji:
    2006
    Wydawca:
    Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
    Tematy:
    hydraulic transients
    method of characteristics
    single pipe
    experimental measurement
    pipe networks
    numerical simulations
    Opis:
    The paper presents results of an experimental and theoretical study of the hydraulic transients in straight pipes and numerical simulations of unsteady flow in pipe networks. A mathematical model consists of a set of partial differential equations of hyperbolic type, which have been transformed by the method of characteristics into ordinary differential equations which are solved by the predictor-corrector method. Experimental tests have been performed, in order to examine the hydraulic transients phenomenon, in a single straight steel pipe. The experiments were carried out in the hydraulic laboratory of the Institute of Water Supply and Water Engineering, Environmental Engineering Faculty, Warsaw University of Technology. The numerical results show that the presented one dimensional model for a single pipe correctly describes the phenomenon since there is a good agreement with experimental maximum and minimum oscillations. In the paper, selected exemplary equations in a difference form for the pipe networks are also presented. One calculation example is given relating to the complex water-pipe network consisting of 17 loops, 48 pipelines and 33 nodes, supplied by two independent sources. Water-hammer throughout the whole pipeline network was caused by closing the gate valve at mid-point of one selected pipe. The results of the numerical calculations are presented in graphic form with respect to the final cross-sections of pipes.
    Źródło:
    Archives of Hydro-Engineering and Environmental Mechanics; 2006, 53, 3; 267-291
    1231-3726
    Pojawia się w:
    Archives of Hydro-Engineering and Environmental Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analytical calculations of surges caused by direct lightning strike to underground intrusion detection system
    Autorzy:
    Aniserowicz, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/200287.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lightning
    transients
    overvoltages
    analytical modeling
    underground cable
    błyskawica
    transjenty
    przepięcia
    modelowanie analityczne
    kabel podziemny
    Opis:
    The paper presents an analysis of overvoltages caused by a direct lightning strike in intrusion detection system equipped with underground radiating cable sensors. Waveforms of currents and voltages in the system components are calculated using analytical formulas basing on a transmission-line model in the frequency domain. The time-domain waveforms are computed using the inverse fast Fourier transform (IFFT). Three network configurations of the intrusion detection system are analyzed.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 263-270
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transformer Modelling for the Frequency and Transient Analyses, with Non-Uniform Inductance Emulating the Inter-Turn Magnetic Coupling
    Autorzy:
    Saied, M. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/262677.pdf
    Data publikacji:
    2014
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    distributed parameter circuits
    frequency response
    modeling
    power system transients
    power transformers
    resonance
    non-uniform
    Opis:
    A new procedure for analyzing power transformer windings with location-dependent circuit parameters, such as the series inductance, is presented. This dependence is introduced in order to take the inter-turn mutual inductive coupling into consideration. It can be expressed either by analytical expressions or even in a tabulated form. The paper addresses both the frequency and time domain analyses. They are based on replacing the winding by an adequate number of equivalent cascade connected two-ports. In contrast to the usual practice of applying the simple medium line representation, each of these two-ports is treated as a long transmission line. Their A, B, C, D generalized circuit constants will be therefore generally location-and frequency-dependent. The analyses will be conducted in the complex s-domain. The corresponding time-domain results can then be obtained by applying a numerical inverse Laplace transform. Expressions for the winding’s input impedance with different treatments of the transformer’s neutral point will be derived for any assumed number of the equivalent two-ports. Results pertinent to the frequency characteristics including the resonance frequencies are presented. The paper also describes the winding’s transient response to the application of two standard voltage stimuli. The suggested approach is validated by its application to a case study for which an analytical closed-form solution is available. The analysis of windings exhibiting nonuniformities in more than one equivalent.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2014, 17, 1; 1-11
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Study on the Low Frequency Transients in Power Transformers and Some Protection-Related Issues
    Autorzy:
    Saied, M. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1203944.pdf
    Data publikacji:
    2014
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    transformer cores
    inrush current
    protection
    transients
    modeling
    equivalent circuit
    low frequency
    nonlinear model
    simulation
    Opis:
    This paper presents typical results for the non-linear low frequency transients following the energization of power transformers. The three operating conditions of no-load, full-load and internal faults are considered. A direct analytical procedure is applied for solving the corresponding set of differential equations describing the transformers equivalent circuit. The core representation is based on the use of curve fitting applied to their magnetization curves. The results include plots versus time for the supply current, the core flux, the magnetizing current as well as the internal induced voltage. Moreover, graphs for the hysteresis loops relating the instantaneous values of both the excitation current and the core flux are given. An approach is also presented for the numerical determination of the amplitudes of the different harmonics existing in any of these signals utilizing the corresponding equidistant samples. As examples, the DC offset as well as harmonics up to the fourth order are considered. It is shown that several useful features can be extracted from the results in both the time and harmonic domains that can assist in differentiating between overcurrents resulting from short-circuits or inrush phenomena.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2014, 17, 2; 9-16
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Obliczenia elektromagnetyczne przetwornika o ruchu złożonym opartego na wspólnym obwodzie magnetycznym
    Analysis of the Dynamic and Stationary States of a Car Starter with Permanent Magnet Motor
    Autorzy:
    Ciurys, M.
    Dudzikowski, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368124.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
    Tematy:
    maszyny elektryczne
    rozruszniki samochodowe
    magnesy trwałe
    przebiegi czasowe
    electrical machines
    car starters
    permanent magnets
    transients
    Opis:
    Using field – circuit method transients of the electric and magnetic quantities of the developed car starter motor with ferrite magnets were determined at dynamic and stationary operating conditions. These results were used, in the developed mathematical model, algorithm and software, to determine mechanical and electrical transient in the system: battery – electrical motor – mechanical transmissions – combustion engine. Transients of the analysed electromechanical system were determined taking into account the variations of inertia, the variations of the load torque generated by combustion engine and the influence of the temperature on the battery parameters, magnets parameters and load torque generated by the combustion engine. Electromechanical characteristics of the car starter were determined.
    Metodą polowo-obwodową wyznaczono przebiegi czasowe wielkości elektrycznych i magnetycznych w opracowanym silniku rozrusznika samochodowego z magnesami ferrytowymi w dynamicznych i ustalonych stanach pracy. Wyniki te wykorzystano w opracowanym modelu matematycznym, algorytmie i programie do wyznaczania przebiegów wielkości mechanicznych i elektrycznych w układzie: akumulator – silnik elektryczny – przekładnie mechaniczne – silnik spalinowy. Wyznaczone przebiegi czasowe w analizowanym układzie elektromechanicznym uwzględniają zmienność momentu bezwładności i zmienność momentu obciążenia generowanego przez silnik spalinowy oraz wpływ temperatury na parametry akumulatora, parametry magnesów i na moment obciążenia generowany przez silnik spalinowy. Wyznaczono charakterystyki elektromechaniczne rozrusznika.
    Źródło:
    Maszyny Elektryczne: zeszyty problemowe; 2013, 3, 100/1; 141-146
    0239-3646
    2084-5618
    Pojawia się w:
    Maszyny Elektryczne: zeszyty problemowe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fuel feed to diesel at a start regime
    Autorzy:
    Fedyanov, E.
    Slavuckiy, V.
    Kanygin, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/246126.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    starting duty
    features of process of giving
    nozzle valve lifting
    injection pressure
    transients
    cyclic fuel delivery
    Opis:
    Some factors defining starting properties of diesel engines are considered. Features of process of fuel feed on a starting mode are analyzed. Basic possibility of steering by processes of mixture forming and combustion is proved at a small speed of a crankshaft. Developed a design procedure of process of fuel feed in a diesel engine at a start regime. On the basis of the theory of transients in a fuel system, the reasons of deterioration of indicators of fuel feed process are explained at a start regime of diesel engine. Possibilities of a method of increase of initial pressure in a delivery highway by prostrating scrolling of a crankshaft with idle spray jets are investigated. The method of intensification of fuel feed process patented by authors used in diesel engine at a start regime. The results of numerical experiments confirming improvement of indicators of process of injection at high-speed speeding up of the pump of a high pressure are resulted: Increase maximum and an average pressure, cutting-down of duration of fuel feed process. The paper concentrates on possibility of improving fuel fed process at the starting regime by means of high speed forcing the fuel pump and the initial pressure rising by an earlier camshaft rotation with out of work injectors.
    Źródło:
    Journal of KONES; 2009, 16, 1; 111-116
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characteristics simulations of the electrodynamic railgun different constructions and their measurement verification
    Autorzy:
    Piekielny, Paweł
    Tomczuk, Bronisław
    Waindok, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/27309948.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    3D field analysis
    analysis of transients
    analytical models
    electrodynamic accelerator
    experimental verification
    field-circuit modeling
    projectile velocity
    Opis:
    Dynamic characteristics for three types of railgun constructions were simulated and measured in this work. The simplest construction is the iron-less (IL) railgun, while the two other ones (IC and ICPM) have an iron-core. The iron-core permanent magnet (ICPM) railgun additionally has permanent magnets. To compare their characteristics, similar dimensions of the rails and iron cores were adopted, and the same power supply system was used. Numerical magnetic field analyses and our analytical models have been used to determine the electromagnetic parameters. They were verified experimentally. The transient states of the railguns were studied with our field-circuit mathematical model, and their results were also verified by experiments.
    Źródło:
    Archives of Electrical Engineering; 2023, 72, 4; 951--969
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transients in Transformers with Non-Uniform Inductance and Capacitance Distributions
    Autorzy:
    Saied, M. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/262695.pdf
    Data publikacji:
    2017
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    distributed parameter circuits
    electromagnetic transients
    integro-differential equations
    modeling
    mutual parameters
    non-uniform
    power transformers
    transient response
    winding
    Opis:
    The electromagnetic transients in transformer windings exhibiting location–dependent inductances and capacitances are investigated in the time domain. Analytical functions describing this dependence are assumed and incorporated in the two integro–differential equations governing the transient voltage and current distributions. The boundary conditions are available from the source initiating the transients and the winding’s end termination. A numerical procedure is applied in order to get frequency domain solutions for the voltage and current in the form of Interpolating and Parametric Functions. The numerical Laplace inversion is then applied to these s–domain expressions. Results pertinent to transients initiated by step- and double-exponential impulse sources are presented and discussed. All possible transformers’ neutral connections are considered. The possible error introduced by neglecting either or both of the inductance and capacitance non-uniformities is addressed. Results indicate that the main error is attributed to neglecting the inductance non-uniformity, whereas the impact of the capacitance non-uniformity is relatively small. In most cases, the winding’s copper and insulation losses have a small effect on the transient response.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2017, 20, 1; 7-14
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transients under energizing multiple power filter circuits
    Autorzy:
    Warecki, J.
    Gajdzica, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/97327.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
    Tematy:
    capacitor
    reactor
    harmonic filter
    C–type filter
    Static Var Compensator
    transient overcurrent
    transient overvoltage
    dynamic overcurrent
    dynamic overvoltage
    switching transients
    Opis:
    The practice of operating reactive power compensation systems involving passive multiple filter circuits (FC) configured by single–tuned filters has shown, that it’s energizing can cause damage of the filter components. Impact of feasible FC configurations, including FC with a C–type filter, on switching overvoltages and overcurrents under the harmonic filters energizing were analyzed. Influence of the filters tuning on transient behavior has been shown. The transient analysis has been carried out by simulating of the FC within Matlab/Simulink software.
    Źródło:
    Computer Applications in Electrical Engineering; 2016, 14; 89-100
    1508-4248
    Pojawia się w:
    Computer Applications in Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Program PSCAD/EMTDC jako wygodne narzędzie do modelowania linii napowietrznych
    Modelling of Overhead Lines by the PSCAD/EMTDC
    Autorzy:
    Smolarczyk, A.
    Chmielak, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/158669.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Elektrotechniki
    Tematy:
    linie napowietrzne
    stany przejściowe
    modelowanie
    PSCAD/EMTDC
    overhead lines
    transients in power systems
    power system modelling
    PSCAD/EMTDC software
    Opis:
    W artykule opisano jeden z programów do symulacji zjawisk dynamicznych występujących w systemie elektroenergetycznym. Program o nazwie PSCAD/EMTDC jest powszechnie używany do modelowania fragmentów systemu elektroenergetycznego i zjawisk w nich występujących. Przedstawiono dostępne w programie modele linii napowietrznych, które mogą zostać wykorzystane do modelowania takich sytuacji jak stany łączeniowe (załączenia, wyłączenia) linii, zwarcia w linii. W programie linie napowietrzne można zamodelować ręcznie za pomocą elementów pasywnych typu R, L, C, z wykorzystaniem gotowych czwórników typu PI, za pomocą gotowych modeli typu Bergeron Model, Frequency Dependent (Mode) Model, Frequency Dependent (Phase) Model. Pokazano przykładowy sposób zamodelowania linii WN 110 kV z wykorzystaniem słupów kratowych typu B2 za pomocą modelu typu Frequency Dependent (Phase) Model.
    The article describes one of the programs for the simulation of dynamic phenomena occurring in the power system. The program called PSCAD/EMTDC is commonly used to model the parts of the power system and phenomena occurring in them. The models of the overhead lines that can be used for modelling situations such as switching states of the line, short-circuit line have been presented. Overhead lines can be manually modelled using passive R, L, C elements by using prepared PI section elements, using prepared Bergeron Model, Frequency Dependent (Mode) Model, Frequency Dependent (Phase) Model. It was shown how to model a high-voltage line 110 kV with the use of type B2 towers by the Frequency Dependent (Phase) Model.
    Źródło:
    Prace Instytutu Elektrotechniki; 2016, 272; 31-48
    0032-6216
    Pojawia się w:
    Prace Instytutu Elektrotechniki
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rozrusznik samochodowy z bezszczotkowym silnikiem prądu stałego
    Car starter with brushless direct current motor
    Autorzy:
    Ciurys, M.
    Dudzikowski, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/320357.pdf
    Data publikacji:
    2006
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    rozruszniki samochodowe
    silniki bezszczotkowe
    magnesy trwałe
    obliczenia
    stany dynamiczne
    car starters
    brushless direct current motors
    permanent magnets
    computations
    transients
    Opis:
    Opracowano model matematyczny, algorytm i program obliczeń przebiegów czasowych wielkości elektrycznych i mechanicznych w układzie: akumulator - rozrusznik samochodowy z bezszczotkowym silnikiem prądu stałego (BLDC) - silnik spalinowy. Opracowany model matematyczny, algorytm i program obliczeń uwzględniają, m.in.: zmienność momentu bezwładności układu korbowego silnika spalinowego, zmienność momentu kompresji i dekompresji gazów w cylindrach oraz zależność momentu tarcia silnika spalinowego od prędkości chwilowej wału korbowego. Obliczono przebiegi czasowe wielkości elektrycznych i mechanicznych w analizowanym układzie.
    A mathematical model, algorithm and program for calculations of electrical and mechanical quantities transients in the system: accumulator — starter with brushless direct current motor - combustion engine were developed (Figs 1, 2, 3). The developed mathematical model, computational algorithm and program take account of the combustion engine crankshaft moment of inertia variations as well as the variations of both the compression and decompression torque in the cylinders and the combustion engine friction torque dependence on the instantaneous crankshaft speed. Transients of electrical and mechanical quantities in the analysed system were calculated (Figs 4, 5).
    Źródło:
    Elektrotechnika i Elektronika; 2006, 25, 2; 129-132
    1640-7202
    Pojawia się w:
    Elektrotechnika i Elektronika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Transient Performance of Partially-Undergrounded Overhead Lines in the Presence of Corona
    Autorzy:
    Saied, Mohamed M.
    Powiązania:
    https://bibliotekanauki.pl/articles/262791.pdf
    Data publikacji:
    2019
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Tematy:
    distributed parameter circuits
    non-uniform lines
    power transmission lines
    line modeling
    transients
    power networks
    mixed
    overhead-cable lines
    partial undergrounding
    distributions
    mathematica
    Opis:
    The paper presents a method for investigating the electromagnetic transients of partially under-grounded high voltage overhead transmission lines in the presence of corona. It is based on a time domain model in which the corona is simulated by distributed voltage-dependent shunt current sources. The line segments and the inserted cable section are represented by a single equivalent transmission element having location-dependent circuit parameters per unit length. The numerical solution of the resulting set of differential equations yields the distributions of the voltage, the longitudinal current and the shunt corona current (per unit length) as functions of location and time. The presented two-, three-dimensional and contour plots proved to be helpful in discussing these distributions and in identifying any eventual current and/or voltage concentrations. The developed computer code in Mathematica can handle any time waveform of the source initiating the transients, any line termination as well as any lengths of the overhead line and cable section.
    Źródło:
    Electrical Power Quality and Utilisation. Journal; 2019, 21, 1; 1-8
    1896-4672
    Pojawia się w:
    Electrical Power Quality and Utilisation. Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wpływ charakterystyk eksploatacyjnych sieci przemysłowych na dobór parametrów filtrów harmonicznych
    Impact of industrial network operating characteristics on the harmonic filter parameters sizing
    Autorzy:
    Warecki, Jurij
    Gajdzica, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/268765.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
    Tematy:
    filtr wyższych harmonicznych
    stany ustalone
    stany przejściowe
    bateria kondensatora
    dławik filtrujący
    harmonic filter
    steady state
    transients
    capacitor bank
    air-core filter reactor
    Opis:
    Układy kompensacji mocy biernej oraz filtracji, oparte na kondensatorach znajdują powszechne zastosowanie w praktycznych rozwiązaniach systemów przemysłowych. Ich parametry znamionowe wyznaczane są wyłącznie w oparciu o harmoniczne prądów oraz napięć w stanach ustalonych, niemniej jednak tyczy się to głównie jednostek filtrujących o prostej topologii. Stąd, mając na uwadze bardziej złożone układy w większości przypadków istniejących lub nowoprojektowanych obiektów wymaga się, aby analizowane układy były dostosowane do pracy zarówno w warunkach ustalonych jak i przejściowych. Korzystając ze standardów oraz norm, w artykule omówiono procedurę doboru parametrów baterii kondensatorów oraz dławików układów filtrujących z pozycji ich bezawaryjnej pracy w elektrycznych sieciach przemysłowych. Zaproponowana metoda ma wspomóż działania projektowe filtrów harmonicznych.
    The application of harmonic filter circuit based on power capacitor banks are widely used in practical solutions in industrial systems. The component ratings of these units are often specified based solely on a combination of steady state fundamental and harmonic voltages and currents. Although, this may be adequate in single-tuned or single branch units and method may not properly rate the components for more complex applications such as multiple, single-tuned harmonic filter circuits in compensated installations. Thus, in the most cases of commonly used or newly designed circuits are required to be adapted to operate as well in steady state and transients conditions. Using the exsisting Standards, the article propose a method for determining equipment ratings parameters of the capacitor banks and air-core filter reactors according to malfunctions. The study illustrated in this paper will be used to support and improve harmonic filter realiability and design. It is hoped that ideas will be a resource for a future filter application guide being contemplated by the capacitor subcommittee.
    Źródło:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2019, 67; 47-51
    1425-5766
    2353-1290
    Pojawia się w:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Stany nieustalone towarzyszące pomiarowi impedancji pętli zwarcia w obwodach wyjściowych zasilaczy bezprzerwowych UPS
    Transient states associating loop impedance measurement in the output line of UPS power supplies
    Autorzy:
    Olesz, M.
    Katarzyński, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/266602.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
    Tematy:
    stany nieustalone
    zasilacze bezprzerwowe
    pomiary jakości energii elektrycznej
    impedancja pętli zwarcia
    transients
    uninterruptible power supplies
    power quality measurements
    fault loop impedance
    Opis:
    W pracy przedstawiono metodykę i wyniki pomiarów stanów nieustalonych w zasilaczu bezprzerwowym (UPS) typu on - line. Do rejestracji zdarzeń po stronie zasilania i na wyjściu UPS wykorzystano dwa przyrządy do pomiaru jakości energii elektrycznej zsynchronizowane czasowo. Rejestratory kompresują uzyskane dane pomiarowe, co może wprowadzać dodatkowe błędy pomiaru wielkości mierzonych – napięć i prądów. Dodatkowe rejestracje oscyloskopem wielokanałowym potwierdziły poprawność danych uzyskiwanych w celu określenia reakcji zasilacza na zaburzenia występujące na wejściu i wyjściu urządzenia. W pracy analizowano wyniki pomiarów impedancji pętli zwarciowej zmierzone przyrządem wymuszającym poziomy prądu zwarciowego na linii zasilającej odbiorniki energii elektrycznej we wszystkich stanach pracy zasilacza, a następnie porównywano je z wynikami obliczeń przeprowadzonych na uzyskanych przebiegach prądu i napięcia.
    The paper presents the methodology and the results of transient measurement in on-line Uninterruptable Power Supply (UPS). There were two power quality measurement instruments (synchronised with time) used for registering the events in UPS input and output. The recorders compress the obtained measurement data, which may introduce additional measurement errors of measured values, i.e. voltage and current. Additional registrations with a multi-channel oscilloscope confirmed the correctness of the obtained data in order to determine the reaction of the UPS to the disturbances occurring in UPS input and output. The work analysed the results of loop impedance, measured by a meter that forces short-circuit current in the line supplying electric load, in all states of the UPS, and then they were compared with the results of calculations carried out on the obtained current and voltage waveforms. The measurement of fault loop impedance in UPS output line should be performed in active static switch (bypass mode), because UPS will operate in this mode after switching from inverter operation due to high current forcing during a short circuit in the UPS output. Measurement of fault loop impedance in UPS output circuits, when it is in AC-DC-AC double conversion mode, may result with loop impedance overstating by meters, which in turn limits recognition of the tested installation as safe from the protection against electric shock by automatic power off point of view. The values of calculated loop impedance at forced high current, i.e. 160 A in the UPS output, when it is respectively in the manual bypass and static switch mode, are 4% and 2.5% lower than the ones presented by meter after measure by forcing high current. Differences in impedance of the static switch and manual bypass UPS mode can be the basis for the estimation of the thyristor impedance. Estimation of direct measurement results with 14.6 m, and according to the calculation of recorded transients it is about 16.1 m.
    Źródło:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2018, 61; 57-60
    1425-5766
    2353-1290
    Pojawia się w:
    Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Time and electric energy losses minimization in speed control of induction motors
    Autorzy:
    Kawecki, L.
    Niewierowicz, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/205536.pdf
    Data publikacji:
    1999
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    optymalizacja
    sterowanie optymalne
    zasada maksimum
    electric energy losses minimization
    electromagnetic transients
    induction motors
    machine control
    optimal control
    optimal frequency starting
    speed control
    Opis:
    The paper presents a method for solving the problem of the simultaneous time and electric energy losses minimization during the frequency speed control of induction motors with the electromagnetic transients. To solve this vector optimization problem, the optimization index in the form of linear combination of the scalar indexes is assumed and the Pontryagin maximum principle is used. Examples of solution for two cases of optimal frequency starting of two induction motors are presented.
    Źródło:
    Control and Cybernetics; 1999, 28, 2; 331-353
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A coupled field-circuit model of a 5-phase permanent magnet tubular linear motor
    Autorzy:
    Tomczuk, B.
    Waindok, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/141318.pdf
    Data publikacji:
    2011
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    silnik synchroniczny liniowy
    magnes trwały
    PMLSM
    metoda polowo-obwodowa
    symulacja
    parametry sterowania
    permanent magnet linear synchronous motors
    field-circuit method
    simulation of the transients
    control parameters
    Opis:
    A method for modeling of the dynamics characteristics for a 5-phase permanent magnet tubular linear motor (PMTLM) is presented. Its electromagnetic nonlinear field analysis with finite element method (FEM) has been coupled with the circuit model. The calculation model includes the equations for electrical circuits and mechanical quantities as well. They have been obtained using Lagrange's method. The calculated and measured waves of the mover position have been compared for several values of the excitation current. This comparison yields a good agreement. Presented calculation model is very useful in designing and optimization of the PMTLM and in the calculation of the parameters for the control algorithms intended for such a type of actuators.
    Źródło:
    Archives of Electrical Engineering; 2011, 60, 1; 5-14
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel power quality data analysis and reporting framework for wide-area system of registration and processing of power quality data
    Autorzy:
    Rezmer, J.
    Leonowicz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/136208.pdf
    Data publikacji:
    2015
    Wydawca:
    EEEIC International Barbara Leonowicz Szabłowska
    Tematy:
    power quality
    faults
    power distribution
    reliability
    power system restoration
    power system transients
    relational databases
    distributed generation
    voltage dips
    GIS
    data visualization
    data analysis
    localization of disturbances
    Opis:
    This paper presents a novel method for data analysis and visualization, including real-time visual monitoring and proposal for combined area PQ indices on the example of the developed and operational comprehensive system of registration, archiving and data processing for the wide-area monitoring of power quality in a separated part of real power grid with distributed renewable generation. Real case studies related to power quality disturbances are presented.
    Źródło:
    Transactions on Environment and Electrical Engineering; 2015, 1, 1; 1-3
    2450-5730
    Pojawia się w:
    Transactions on Environment and Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Multi-spark modeling of very fast transient overvoltages for the purposes of developing HV and UHV gas-insulated switchgear and of conducting insulation co-ordination studies
    Autorzy:
    Szewczyk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/200835.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    very fast transient overvoltages
    VFTO
    gas insulated switchgear
    GIS
    disconnector switch
    DS
    modeling
    simulations
    transients
    switching
    mitigation
    breakdown voltage
    BDV
    odłącznik
    modelowanie
    symulacje
    transjenty
    przełączanie
    łagodzenie
    rozdzielnice izolowane gazem
    Opis:
    Very fast transient overvoltages (VFTO) originate from steep voltage breakdowns in SF6 gas that are inherent to operation of any switching device of the gas-insulated switchgear (GIS) type. For power stations with voltage ratings exceeding 500 kV, the ratio between equipment rated- and withstand-voltage levels becomes relatively low, which causes the VFTO peak values to reach the component’s insulation withstand-voltage levels, thus becoming a design factor for high- and ultra-high voltage GIS. While well-established approach to VFTO analyses involves only single VFTO events (the so-called single-spark approach), there is often the need to analyze the entire VFTO generation process, for which the multi-spark approach to VFTO modeling is to be employed. The multi-spark approach allows one to evaluate the VFTO impact on the GIS disconnector design along with the impact of the VFTO on selection and dimensioning of the VFTO damping solutions. As the multi-spark approach to VFTO modeling is now being increasingly used in UHV GIS developments as well as for the insulation co-ordination studies of power stations, the present paper is motivated by the need to report on the VFTO multi-spark modeling approach and to lay a common ground for development works that are supported extensively with VFTO simulations. The paper presents physical assumptions and modeling concepts that are in use in such modeling works. Development of the multi-spark GIS disconnector model for VFTO simulations is presented, followed by an overview of examples of the model application for the GIS development works and for insulation co-ordination studies.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 6; 871-882
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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