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1

Badanie stanów nieustalonych w obwodach liniowych

Wieczorek Arkadiusz, Suproniuk Marek, Paziewski Piotr

Elektronika : konstrukcje, technologie, zastosowania

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2023

|

Vol. 64, Nr 2

32--36

PL

Artykuł powstał w oparciu o pracę dyplomową zrealizowaną przez studenta Wojskowej Akademii Technicznej. W artykule przybliżono tematykę stanów nieustalonych w obwodach RLC. Autorzy zaprezentowali aplikacje wykonaną w środowisku Matlab umożliwiającą uzyskanie przebiegów napięć na elementach obwodu dla podstawowych układów RLC. Wyniki symulacji zostały zweryfikowane z pomiarami laboratoryjnymi.

EN

The article is based on a thesis made by a student of the Military University of Technology. The article presents the topic of transients in RLC circuits. The authors presented an application made in the Matlab environment that allows obtaining voltage waveforms on circuit elements for basic RLC circuits. The simulation results were verified with laboratory measurements.

2

Numerical simulation of the liquid distribution problem by an adaptive flow distributor

Rutkevych Volodymyr, Kupchuk Ihor, Yaropud Vitalii, Hraniak Valerii, Burlaka Serhii

Przegląd Elektrotechniczny

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2022

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R. 98, nr 2

64--69

EN

The article presents a numerical modeling of the adaptive flow divider, which allows you to adjust the supply of the U-shaped frame according to the change in load acting on the mechanism for cutting and unloading the stem feed. The use of adaptive flow divider in the hydraulic drive system of the mechanism for cutting and unloading allows to stabilize energy consumption for separation of a portion of stem feed under the condition of change and fluctuation of parameters that significantly affect the process of separation and unloading of stem feed from monolith. On the basis of the carried out numerical modeling recommendations on a choice of constructive parameters of an adaptive flow divider are given.

PL

W artykule przedstawiono modelowanie numeryczne adaptacyjnego dzielnika przepływu, który umożliwia regulację zasilania ramy w kształcie litery U w zależności od zmiany obciążenia działającego na mechanizm cięcia i odciążania posuwu łodygi. Zastosowanie adaptacyjnego rozdzielacza przepływu w hydraulicznym układzie napędowym mechanizmu cięcia i rozładunku pozwala ustabilizować zużycie energii na oddzielenie porcji podawczej łodygi pod warunkiem zmiany i wahań parametrów, które istotnie wpływają na proces rozdzielania i rozładunku pasza z łodygi z monolitu. Na podstawie przeprowadzonego modelowania numerycznego podano zalecenia dotyczące doboru parametrów konstrukcyjnych adaptacyjnego dzielnika przepływu.

3

Control of operability of Peltier modules in cooling systems based on the analysis of transient operating modes

Kuzichkin Oleg Rudolfovich, Konstantinov Igor Sergeevich, Vasilyev Gleb Sergeevich, Surzhik Dmitry Igorevich

Archives of Thermodynamics

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2021

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Vol. 42, no 2

31--42

EN

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.

4

Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 2: Small Normalised Voltage Command

Reznikov Boris, Ruderman Alex, Galanina Valentina

Power Electronics and Drives

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2020

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Vol. 5 (40)

41--57

EN

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.

5

Analysis of Transients in a 4-Level Flying Capacitor Converter: Time Domain Approach. Part 1: Large Normalised Voltage Command

Reznikov Boris, Ruderman Alex, Galanina Valentina

Power Electronics and Drives

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2020

|

Vol. 5 (40)

27--40

EN

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.

6

Vibration transients of reservoir-pipe-valve system caused by water hammer

Miao Yang, Jiang Yuncheng, Qiu Zaihui, Pan Jun, Wang Lu, Han Zhenrong, Li Kun, Zhang Li, Zhang Xiaolu

Journal of Theoretical and Applied Mechanics

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2020

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Vol. 58 nr 4

1037--1048

EN

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.

7

Wpływ charakterystyk eksploatacyjnych sieci przemysłowych na dobór parametrów filtrów harmonicznych

Warecki Jurij, Gajdzica Michał

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

|

2019

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Nr 67

47--51

PL

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.

EN

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.

8

Switching overvoltage analyses under distorted supply voltage conditions

Chmielewski Tomasz, Oramus Piotr, Kuczek Tomasz

Przegląd Elektrotechniczny

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2019

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R. 95, nr 3

119--125

EN

This paper presents the impact of the higher harmonics presence in the supply voltage on the generated transient recovery voltage (TRV), which inherently appear between circuit breaker contacts (CB) after current interruption. In the current version the international standards from committees such as CIGRE or IEC are silent about this topic. The research presented in this paper, includes laboratory experiments and simulations, for ideal supply voltage conditions and the supply voltage with certain harmonic content. The black-box conductance model of electric arc, based on Cassie-Mayr equation was used for the simulations.

PL

Artykuł przedstawia analizę wpływu wyższych harmonicznych w napięciu zasilającym na napięcie powrotne (TRV) pojawiające się między stykami wyłącznika po przerwaniu prądu. Motywacją do powstania artykułu stał się fakt, iż normy międzynawowych komitetów takich jak CIGRE czy IEC w obecnych wersjach nie poruszają tego zagadnienia. Artykuł zawiera wyniki analiz oraz eksperymentów laboratoryjnych dla warunków bez harmonicznych oraz z harmonicznymi obecnymi w napięciu zasilającym. W symulacjach zastosowano model łuku elektrycznego w oparciu o równania Cassiego – Mayra.

9

The Transient Performance of Partially-Undergrounded Overhead Lines in the Presence of Corona

Saied Mohamed M.

Electrical Power Quality and Utilisation. Journal

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2019

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Vol. 21, iss. 1

1--8

EN

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.

10

Analytical calculations of surges caused by direct lightning strike to underground intrusion detection system

Aniserowicz K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2019

|

Vol. 67, nr 2

263--270

EN

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.

11

Stany nieustalone towarzyszące pomiarowi impedancji pętli zwarcia w obwodach wyjściowych zasilaczy bezprzerwowych UPS

Olesz M., Katarzyński J.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

|

2018

|

Nr 61

57--60

PL

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.

EN

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.

12

Algorytm wyznaczania sygnatury odbiornika energii elektrycznej z wykorzystaniem transformaty falkowej

Wójcik A., Winiecki W., Łukaszewski R.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 11

39--42

PL

W artykule opisano algorytm wyznaczania sygnatur urządzeń elektrycznych poprzez charakteryzację stanów przejściowych występujących podczas włączania urządzeń. Do przetwarzania sygnału prądu wykorzystano transformatę falkową dedykowaną do analizy sygnałów niestacjonarnych. Przedstawiono sposób obliczania parametrów liczbowych charakteryzujących urządzenia oraz przykładowe wyniki badań eksperymentalnych. Zaproponowano metodę oceny jakości wyznaczonych sygnatur.

EN

The paper presents an algorithm for determining features of electrical appliances by characterizing switch-on transients. A wavelet transform dedicated to non-stationary signals analysis was used for current signal processing. The method of numeric parameters calculations characterizing devices and some results of experiments are presented. A method for patterns evaluation has been proposed.

13

Use of 3-dimensional finite elements for computation of temperature distribution in the Stator of an Induction Motor during Direct-On-Line Starting

Bhattacharya N. K., Naskar A. K., Sarkar D.

Journal of Power Technologies

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2017

|

Vol. 97, nr 4

347--353

EN

Transient thermal analysis of induction machines is a subject of interest for machine designers in their effort to improve machine reliability. Since the stator is static, it is prone to overheating. Therefore, the study of transient thermal behavior in the stator is useful to identify causes of failure in induction machines. This paper presents a three-dimensional transient heat flow through the stator of an induction motor using arch shaped elements in the r-θ-z plane of the cylindrical co-ordinate system. A temperature-time method is employed to evaluate the distribution of loss in various parts of the machine. Using these loss distributions as an input for finite-element analysis, more accurate temperature distributions can be obtained. The model is applied to one squirrel cage Totally Enclosed Fan Cooled (TEFC) machine of 7.5 kW. Finally, the temperatures obtained by this three-dimensional approximation at different locations of the stator were compared for different stator currents considering the time required for each stator current during the transient in Direct-On-Line starting.

14

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

Szewczyk M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

|

Vol. 65, nr 6

871--882

EN

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.

15

Investigation of the stator inductances of the expanded Park model and an approach on parameter identification using the evolution strategy

Schmuelling Ch., Kreischer Ch., Gołebiowski M.

Archives of Electrical Engineering

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2016

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Vol. 65, nr 3

585--599

EN

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.

16

The modeling of centrifugal pump transients

Szymczyk J., Karaśkiewicz K.

Transactions of the Institute of Fluid-Flow Machinery

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2015

|

nr 130

83--92

EN

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.

17

Analysis of a brushless DC motor integrated with a high-pressure vane pump

Ciurys M., Dudzikowski I.

Czasopismo Techniczne. Elektrotechnika

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2015

|

Y. 112, iss. 1-E

407--416

EN

A new design of a brushless direct current motor is introduced in this paper. In the BLDC motor, a high-pressure vane pump is built into the rotor. The motor is excited by neodymium magnets. Its nominal power is 2.5 kW. The motor is built in such a way that the magnetic field does not penetrate the pump. A magnetic structure field analysis of the motor was performed. Demagnetization resistance of the magnets was determined. By the use of time stepping, finite element method waveforms of the electrical and mechanical parameters in the BLDC motor–inverter system were determined.

PL

Opracowano nową konstrukcję silnika bezszczotkowego (BLDC ), w którego wirnik wbudowana jest wysokociśnieniowa pompa łopatkowa. Silnik wzbudzany magnesami neodymowymi ma moc 2,5 kW. Zbudowany jest w taki sposób, aby pole magnetyczne nie wnikało do wnętrza pompy. Przeprowadzono polową analizę obwodu magnetycznego silnika. Wyznaczono odporność magnesów na odmagnesowanie. Metodą polowo-obwodową wyznaczono przebiegi czasowe wielkości elektrycznych i mechanicznych w układzie silnik–przekształtnik.

18

A Study on the Low Frequency Transients in Power Transformers and Some Protection-Related Issues

Saied M. M.

Electrical Power Quality and Utilisation. Journal

|

2014

|

Vol. 17, iss. 2

9--16

EN

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.

19

Analiza pracy prądnicy trójfazowej z magnesami trwałymi w elektrowni wiatrowej małej mocy

Ciurys M., Bańka M., Dudzikowski I.

Przegląd Elektrotechniczny

|

2013

|

R. 89, nr 2b

120--123

PL

Opracowano algorytm i program obliczeń projektowych prądnic trójfazowych z magnesami trwałymi. Zastosowano metodę obwodowo-polową. Zaprojektowano prądnicę oraz wyznaczono jej parametry ruchowe podczas pracy przy różnej prędkości obrotowej, w różnej temperaturze otoczenia. Dobrano układ stabilizacji napięcia oraz zamodelowano układ: generator – układ stabilizacji napięcia – odbiory. Wyznaczono przebiegi czasowe w analizowanym układzie.

EN

An algorithm and a program for designing of the three-phase generators with permanent magnets were developed. Circuit-field method was used. By the use of the developed algorithm and program permanent magnet generator was designed and its operating parameters at different speed and at different magnet temperature were determined. The system: generator - voltage stabilization system – loads was modeled. Voltage and current transients in the analyzed system were determined.

20

Wieloskalowe modelowanie przepływu w rejonie ściany – wybrane zagadnienia

Krawczyk J., Janus J., Ostrogórski P., Pałka T.

Prace Instytutu Mechaniki Górotworu PAN

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2013

|

Vol. 15, no. 1-2

31--39

PL

Systemy wentylacyjne kopalń głębinowych są zbyt rozległe i złożone, by przy wydajności współczesnych komputerów prowadzić dla całych obiektów symulacje metodą objętości skończonej. Z tego powodu są modelowane wybrane fragmenty sieci. Dla procesów stacjonarnych pominięte obszary mogą być zastąpione przez warunki na brzegach. Podczas stanów przejściowych dynamiczne własności pominiętych obszarów sieci mogą mieć istotny wpływ na przebieg zjawiska. Skutecznym rozwiązaniem może być wyodrębnienie sieci wentylacyjnej podobszaru, gdzie dokładny opis jest szczególnie uzasadniony. Podobszar ten będzie modelowany metodą objętości skończonej z użyciem dwu lub trójwymiarowego opisu. Dla pozostałej części sieci stosowany jest prostszy, jednowymiarowy opis. W ten sposób może być reprezentowana całą sieć wentylacyjna, lub jej rozległy fragment. Opracowano metodę współbieżnej symulacji niestacjonarnych przepływów, w której w kolejnych krokach czasowych programy symulacyjne wymieniają ze sobą dane, aktualizując warunki brzegowe w strefach łączących podobszar wymagający dokładniejszego opisu z pozostałą częścią sieci. Metoda ta ma zastosowanie zarówno dla jednowymiarowego quasi statycznego opisu użytego w programie Ventgraph jaki dla pełniejszego jednowymiarowego opisu przepływu mieszaniny gazów doskonałych. Opracowano specjalną wersję programu Ventgraph, która współpracuje z oprogramowaniem do symulacji metodą objętości skończonej. Podano przykład zastosowania metody dla rejonu ściany wydobywczej. Metodę objętości skończonej zastosowano dla końcowego odcinka chodnika podścianowego, samej ściany oraz początkowego odcinka chodnika nadścianowego. Dla pozostałych wyrobisk rejonu ściany zastosowano opis jednowymiarowy.

EN

Ventilation networks in deep mines are too large and complex to enable the simulation of the entire object by the finite volume method, moreover present day computers are not powerful enough, so selected sections of the network have to be modelled instead. In the case of stationary processes, the omitted regions can be replaced by boundary conditions. During the transients, however, dynamic properties of the omitted portions of the network may strongly influence the flow processes. In a solution presented here certain sub-regions of the network are determined, which require the most accurate description. This sub-region can be modelled by the finite volume method, using a 2D or 3D model. The remaining part of the ventilation network is modelled by a simple, 1D model so the entire network can be represented or its selected fragment only. The method was developed that enables concurrent simulation of non-stationary flows, enabling the data exchange between the simulation programs in the subsequent time steps to update the boundary conditions in zones connecting the sub-region requiring the most accurate description and the remaining parts of the ventilation network. This method is well applicable both to 1D quasi-static description used in the Ventgraph software and to a fuller 1D flow model of a mixture of ideal gases. The new version of the Ventgraph program was developed, which interacts with the finite volume simulation software. The method is then applied to investigation of the ventilation conditions in a longwall region. The finite volume method is applied to handle the final section of the maingate, the lonwall and the inlet section of the tailgate. The remaining parts of the longwall region are described by a 1D model.