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Wyświetlanie 1-15 z 70
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:
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:
Modelling of synchronous generators for the analysis of frequency transients above 1 Hz/s
Autorzy:
Assenkamp, Alf
Powiązania:
https://bibliotekanauki.pl/articles/2135729.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
control system
distributed energy systems
frequency support
generator model
RoCoF
synchronous generators
synchronous machines
Opis:
Large synchronous generators are of high importance for the stability of power systems. They generate the frequency of the system and stabilize it in case of severe grid faults like trips of large in-feeders or loads. In distributed energy systems, in-feed via inverters will replace this generation in large parts. Modern inverters are capable of supporting grid frequency during severe faults by different means on the one hand. On the other hand, higher Rates of Change of Frequency (RoCoF) after incidents need to be accustomed by future systems. To be able to analyse the RoCoF withstand capability of synchronous or induction generators, suitable models need to be developed. Especially the control and excitation system model need enhancements compared to models proposed in standards like IEEE Std 421.5. This paper elaborates on the necessary modelling depth and validates the approach with example results.
Źródło:
Archives of Electrical Engineering; 2022, 71, 3; 687--700
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
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:
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:
Effects of a water hammer and cavitation on vibration transients in a reservoir-pipe-valve system
Autorzy:
Miao, Yang
Qiu, Zaihui
Zhang, Xiaolu
Jiang, Yuncheng
Pan, Jun
Liu, Yi
Zhang, Li
Li, Kun
Powiązania:
https://bibliotekanauki.pl/articles/2055065.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
reservoir-pipe-valve system (RPV system)
water hammer
vibration
cavitation
Opis:
An extraordinary phenomenon with violent oscillation, accompanied by an abnormal “click” sound is observed during the valve closing in a fuel feeding pipe system. A fluctuation model with flow cavitation, in which time-varying stiffness, time-varying damping coefficients and flow cavitation are comprehensively considered, is proposed. On this basis, a dynamic vibration equation is established and an expression of flow pressure at the valve port is derived. The critical displacement of the flow cavitation system is defined. When the vibration amplitude reaches the critical displacement, cavitation occurs. Based on this model, simulation of vibration displacement and flow pressure is given. The simulated transient process shows the phenomena of vibration fluctuation with cavitation. The results are compared with the experimental data measured by a pressure sensor. Under our experimental conditions, the critical displacement of vibration is 1.41mm, and the average relative pressure peak error is 0.022. The comparison between the simulation and experimental results shows that they are in an acceptable agreement.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 4; 611--622
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
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:
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:
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:
Analysis of Transients in a Three-Level DC–DC Flying Capacitor Converter. Time Domain Approach
Autorzy:
Reznikov, Boris
Ruderman, Alexander
Galanina, Valentina
Powiązania:
https://bibliotekanauki.pl/articles/1193695.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
three-level DC–DC converter
flying capacitor
transient
natural balancing
Opis:
The paper considers a discrete state-space model for transients in a three-level flying capacitor DC–DC converter. A transition matrix is obtained for a pulse width modulation (PWM) period. The matrix elements are expanded into a power series using a selected small parameter. The matrix eigenvalues that determine the natural balancing dynamics transients are presented in the form of power series as well. Four separate transients are constructed based on four possible PWM period initial states (topologies). Inductor current and capacitor voltage transients are found for the voltage source power-up as the arithmetic average of the four separate transients. The discrete solutions are replaced by continuous ones. The resulting transients that are elementary functions of the circuit parameters, PWM period, and voltage reference demonstrate good agreement with the simulation results.
Źródło:
Power Electronics and Drives; 2019, 4, 39; 33-45
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
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:
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:
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
Wyświetlanie 1-15 z 70

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