Wyniki 1-10 spośród 11 dla zapytania: authorDesc:"Tetyana KORENKOVA"

Enhancement of instantaneous power method in the problems of estimation of electromechanical complexes power controllability

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A power approach to estimation of electromechanical complexes controllability using instantaneous power method has been offered. It has been determined that power controllability characterizes the quality of energy conversion processes in the system, reflects manifestation of nonlinear properties of the object. A mathematical procedure for determination of power losses for the whole power channel of electromechanical complex power conversion has been developed. It has been shown that formation of balance equations of separate instantaneous power components underlies the estimation of electromechanical complexes power controllability. Streszczenie. Zaproponowano sposób oszacowania sterowności zespołów elektromechanicznych przy użyciu metody mocy chwilowej. Zostało określone, że sterowność mocy charakteryzuje jakość energii w procesie jej przekształcania oraz przedstawia własności nieliniowe obiektu. Rozwinięto procedurę matematyczną dla określenia start mocy w całym kanale mocy układów elektromechanicznych. Pokazano, że utworzenie równań równowagi dla składników mocy chwilowej leży u podłoża oszacowania sterowności układów elektromechanicznych. (Używanie metody mocy chwilowej w problemach oszacowania sterowności mocy w układach elektromechanicznych) Keywords: electromechanical systems, instantaneous power, effective power, power controllability, nonlinear systems, power conditioning. Słowa kluczowe: systemy elektromechaniczne, moc chwilowa, moc skuteczna, sterowność mocy, systemy nieliniowe. Introduction The problem of estimation of system controllability is rather extensive; it touches upon various spheres of activity - informational, social, technical ones, etc. One of the ways of controllability formalization consists in singling out the most significant practical activity sectors as possible objects of research, as well as development and application of formally new approaches to controllability estimation with this point in view. T[...]

Power criterion in problems of leakage identification in hydrotransport complex

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The use of power criterion obtained on the basis of frequency analysis of hydraulic power signal in the problems of leakage identification is substantiated. It is shown that leakage formation in a pipeline system is accompanied by distortion of hydraulic power signal, appearance of higher order harmonics, growth of instantaneous power sine component. It is offered to use power distortion nonlinear coefficient as information index when a leakage in the hydrosystem is identified. Streszczenie. W pracy uzasadniono użycie kryterium mocy otrzymane na bazie analizy częstotliwości hydraulicznego sygnału mocy w problemach identyfikacji upływu. Pokazano, że formowanie upływności w systemie rurociągowym jest stowarzyszone z zaburzeniem hydraulicznego sygnału mocy, obecności harmonicznych wyższego rzędu, wzrost mocy chwilowej w harmonicznej podstawowej. Zaoferowano użycie nieliniowego współczynnika zaburzenia mocy jako wskaźnika informacyjnego kiedy identyfikowany jest upływ w hydrosystemie. (Kryterium mocy w problemach identyfikacji upływu systemach hydrotransportowych). Keywords: hydrotransport complex, leakage, mathematic model, hydraulic power, power processes. Słowa kluczowe: system hydrotransportowy, upływ, model matematyczny, moc hydrauliczna, procesy mocowe. Introduction In the process of operation of hydrotransport complexes (HTC) of public and industrial water supply systems, oiltransfer stations, etc. conditions under which technological parameters (head and flow) exceed their overload capacities are possible. As a result of this, various contingencies: hydraulic impacts, leakages, cavitations, surge, etc. may occur [1]. The most common undesirable phenomena include pipeline network leakages conditioned by unsatisfactory technical state of the water-mains, increased dynamic loads when pump parameters are regulated, abrupt actuation of protective fittings, illegal liquid withdrawal, etc. Existing methods of diagnostics of leakages an[...]

Energy and resource saving control system for pumping station

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Energy and resource saving control system for pumping station is offered. Its formation is based on a complex approach to the estimation of power processes in all the elements of power channel, taking into account the real conditions of consumer operation and changing operating characteristics of hydraulic equipment. The system enables substantiation of the choice of power efficient operation conditions and expedience of hydraulic equipment further operation. Streszczenie. Artykuł dotyczy zagadnienia oszczędności energii I zasobów w stacji pomp, poprzez zastosowanie proponowanego systemu sterowania. Przy jego opracowywaniu zastosowano złożony sposób estymacji procesów energetycznych, biorący pod uwagę zarówno rzeczywiste warunki poboru przez odbiorcę jak i zmienną charakterystykę pracy urządzeń hydraulicznych. (Oszczędzający energię i zasoby system sterowania dla stacji pomp). Keywords: power conditions, pumping station, power losses distribution, power efficiency. Słowa kluczowe: warunki energetyczne, stacja pomp, rozkład strat mocy, sprawność energetyczna. Introduction Pumping stations (PS) of water supply systems present a complicated electro-hydraulic system including a distribution network, pumping unit (an electric motor with a pump on a shaft), pipe fitting, a manifold pipeline system. Operation conditions of water supply and drainage systems PS are determined by the schedule of consumption of the operating environment by consumers, constantly changing and depending on the population, enterprises routine of work, climatic conditions, season, day of the week, time of the day, etc [1]. To bring a pumping unit (PU) operating conditions in conformity with the current water consumption the change of the pump driving motor rotation frequency has been recently used more and more often. Controlled electric drive systems provide up to 10-50 % of energy saving, smooth variation of PU technological parameters, decrease of leakage [1,[...]

Identification of electrohydraulic complex parameters using instantaneous power components

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It is proved that identification of electrohydraulic complex parameters is to be based on equations of power balance of all the components of power channel instantaneous power. An electrohydraulic complex equivalent circuit with division of parameters into active resistance and inductive reactance is proposed, which makes it possible to take into consideration inertial loss of head in the pipeline. A sufficient number of identification equations for determination of the hydrosystem necessary parameters are obtained. It is pointed out that the offered energy method can be used to solve problems of identification of parameters of electrohydraulic complexes with group operation of pump units with controlled and uncontrolled pump electric drive. Streszczenie. Przedstawiono metodę identyfikacji parametrów złożonego układu elektrohydraulicznego bazującą na równaniach bilansu mocy. System hydrauliczny jest reprezentowany przez rezystancję i indukcyjność. Zaproponowana metoda może służyć do analizy systemu złożonego z pomp sterowanych elektrycznie. Identyfikacja złożonego systemu elektrohydraulicznego bazująca na chwilowych składowych mocy Keywords: electrohydraulic complex, instantaneous power, equations of power balance, identification system, equivalent circuit. Słowa kluczowe: system elektrohydrauliczny, moc chwilowa, bilans mocy Introduction Conditions causing occurrence of nonstationary hydrodynamic processes often take place in the practice of electrohydraulic complexes (EHC) operation. This, in its turn, results in time variations of the main parameters of pump units and pipeline network: head, discharge, efficiency, hydraulic resistance of the pump and hydraulic network [1]. Any variation in EHC operation condition causes redistribution of power at the elements of power channel: electric power supplied to the mechanism shaft, mechanical power of the electric motor, hydraulic power at the pump output, in pipeline network and at the c[...]

Limits of noncavitation operation of an electrohydraulic complex with a variable-frequency electric drive DOI:10.15199/48.2015.01.49

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A method for determination of the limits of noncavitation operation of an electrohydraulic complex with a variable-frequency electric drive is proposed. An analytical expression for determination of the critical value of a relative rotation frequency of an induction motor is obtained. This expression provides a noncavitation operation of a hydrotransport system. A mathematical model of an electrohydraulic complex with a variablefrequency electric drive and a cavitation channel in the pipeline network is given. The obtained curves of pressure variation in the hydraulic system confirm the possibility of provision of cavitation protection of an electrohydraulic complex by means of a variable-frequency electric drive. Streszczenie. W artykule zaproponowano metodę określenia granic działania niekawitacyjnego systemu elektrohydraulicznego z elektrycznym napędem o zmiennej częstotliwości. Wyznaczono analityczną zależność na wyznaczanie wartości krytycznej względnej częstotliwości kołowej. Zależność ta opisuje niekawitacyjne działanie systemu transportu cieczy. Utworzono model matematyczny urządzenia elektrohydraulicznego z napędem elektrycznym o zmiennej częstotliwości oraz kanału kawitacyjnego w sieci wodociągowej. Otrzymane zależności zmienności ciśnienia w systemie hydraulicznym potwierdzają możliwość ochrony kawitacyjnej systemu elektrohydraulicznego z napędem elektrycznym ze zmienną częstotliwością. (Ograniczenia niekawitacyjnego działania systemu elektrohydraulicznego z napędem elektrycznym o zmiennej częstotliwości). Keywords: electrohydraulic complex, cavitation processes, variable-frequency electric drive. Słowa kluczowe: system elektrohydrauliczny, procesy kawitacyjne, napęd elektryczny ze zmienną częstotliwością Introduction Pump units (PU) and electrohydraulic complexes (EHC) on their basis present a united complex system of interacting electromechanical and hydraulic equipment in which regulation of PU process-dependent parameters is[...]

Pump complex electric drive control system taking into account cavitation processes in the pipeline DOI:10.15199/48.2015.12.58

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It has been determined that cavitation processes in a pump complex are characterized by gas-vapor mixture considerable power that may make up to 25% of hydraulic power of the liquid flow. A mathematical model of a pump complex electric drive control system with a device for recuperation of gas-vapor mixture energy is given. The obtained curves of pressure variation in the hydrosystem have proved the possibility of provision of cavitation protection for electrohydraulic complex by means of a variable-frequency electric drive. Streszczenie. Zostało wykazane, że procesy kawitacji w układzie pompowym są charakteryzowane przez opary gazu, podnoszące moc hydrauliczną o 25 procent. Pokazano model matematyczny systemu kontroli układu pomp wraz z urządzeniem do rekuperacji energii oparów gazowych. (Otrz7ymane krzywe zmienności ciśnienia w hydrosystemie wskazały na możliwość aplikacji ochrony kawitacyjnej w układzie elektrohydraulicznym przez użycie napęcu elektrycznego o zmiennej częstotliwości. (System sterowania napędu elektrycznego zespołu pomp przy wykorzystaniu procesów kawitacji w rurze). Keywords: electrohydraulic complex, cavitation processes, controlled electric drive. Słowa kluczowe: układ elektrohydrauliczny, procesy kawitacyjne, sterowany napęd elektryczny. Introduction If liquid flow pressures decreases or the temperature of the pumped medium changes, the operation mode of pump complexes (PC) is accompanied by development of cavitation processes in the pipeline system. Cavitation is characterized by periodic generation and collapse of cavitation cavities filled with vapor or gas. Such operation modes result in increased wear of hydraulic equipment, variation of PC processdependent parameters, pipeline chocking and, consequently, growth of liquid transportation power losses [1, 2]. Conventional means of cavitation processes control are based on installation of pipeline protection, adding admixtures to the liquid, injection of liqu[...]

The automation of the procedure of the electrohydraulic complex power harmonic analysis DOI:10.15199/48.2018.01.01

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Electrohydraulic complexes (EHC) represent a complicated energy conversion system. When the modes of EHC operation change, the conditions for occurrence of such non-stationary hydrodynamic processes as: head pulsations, surges, cavitation oscillations, etc. are created [1-3]. The analysis [1, 2] revealed that EHCs are characterized by low controllability of electrohydraulic equipment in nonstationary operation modes. It results in occurrence of various emergency situations. Moreover, the conventional methods to EHC equipment control in emergency situations solve only local problems and work when a breakage really takes place. Papers [4, 5] contain the proof of the direct relation of EHC controllability and the processes of energy consumption or generation in the power channel. In this case time-variable power component characterizes the process of energy exchange between the EHC elements and results in reduction of its energy controllability. Taking the above said into consideration, the automation of the procedure of the harmonic analysis of the processes of energy conversion in EHC power channel is relevant. It enables to determine the technological contour nonlinear processes influence on the hydrosystem energy modes. Research method When various non-stationary processes occur in the pipeline system, energy processes in EHC are of the character of periodic steady oscillations of power at the analyzed time interval [6, 7]. So, cavitation processes occurrence in the hydrosystem results in periodic time variation of the head and discharge. It, in its turn, changes the load condition of PU operation which results in the variation of the electric current and, consequently, the electromagnetic power supplied to the motor stator windings. The above said allows presentation of the signals of voltage and current, head and discharge by a generalized Fourier series and also provides approximation of the signals of power (electri[...]

The principles of the creation of the control system for the pumping complex variable-frequency electric drive, taking into account the alteration of the current parameters of the hydrosystem DOI:10.15199/48.2018.12.09

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In the practice of pumping complexes (PC) operation, there often occur unsteady processes caused by the development of complex hydrodynamic phenomena: surges, cavitation oscillations, turbulent modes, water hammers, etc. [1, 2]. The unstable flow of liquid in the hydrosystem characterized by the alteration of the head and discharge signals in time accompanies them. PC operation in the unsteady modes results in the deviation of the parameters (resistive impedance, inductance and capacitance) of the pump unit (PU) and the hydronetwork from their rated values and, consequently, in the inefficient operation of the electrotechnical equipment. The shift of the point of PC operation mode causes it and results in the reduction of PU efficiency. Taking into consideration the above said, when developing automatic control systems (ACS) with a variable-frequency electric drive (VFED) of PC, solving the basic technological problem (the stabilization of the head or discharge in the hydronetwork). It is necessary to take into account the alteration of the current parameters of the pumping and pipeline equipment resulting in the deviation of PC operation mode from the domain with the maximal possible efficiency. Research method Fig. 1 contains a block diagram of the extreme ACS of PC VFED, with the maintenance of the required pressure at the consumer, including: a pump (P) with a drive induction motor (IM), a frequency converter (FC) connected to IM stator windings, a pipeline network, a consumer (C), a controlled stopcock (S) with an actuating mechanism (AM), pressure sensors (PS1-PS3) and discharge sensors (DS1-DS3), a velocity sensor (VS), a calculation block (CB) containing an input data block (IDB), a setting signal formation block (SSFB), a power determination block, a frequency analysis block (FAB), a block for the determination of the pump efficiency (BDE), a parameter identification block (PIB), comparison devices (CD1, CD2), a[...]

The diagnostics of the emergency modes of the variablefrequency electric drive of the pumping complex DOI:10.15199/48.2019.02.24

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At frequent switch on/off of the pumps, sharp shutting the stopcock, switch of the pipelines, unplanned change of the schedule of water consumption, etc. in PC pipeline network there appear wave processes of different amplitude and frequency. They may result in the occurrence of emergency modes such as water hammer, leakage, cavitation, pipeline clogging and others. Papers [1 - 4] contain a rather wide analysis of the wave processes in PC pipeline network. Therefore, paper [1] analyzes the problem of the diagnostics and localization of leakages in pipeline networks; paper [2] research the wave processes in the head pipeline at the water hammer; papers [3, 4] describe the cavitation phenomena in the impellers of the centrifugal pumps and the pipeline network. One should keep in mind that in most cases the above mentioned emergency modes are considered only from the point of view of hydrodynamics and do not take into account the pipeline network wave processes influence on the characteristics of the electrohydraulic complex on the whole. The above said determines the topicality of the problems related to the diagnostics of the emergency modes in PC variable-frequency electric drive for the timely response to the development of the contingency situations in the pipeline network and warning the maintenance staff. Research method To research the emergency modes of PC operation we created a mathematical model of the automatic control system (ACS) for the pump variable-frequency electric drive with the function of the stabilization of the pressure in the consumer’s network. The block diagram (Fig. 1) of the proposed model includes: a model of the frequency converter (FC); a PI-regulator; a model of an induction motor (IM) in u,v,0-coordinates; a model of the pump with a block of setting the coefficients of the turbomechanism published characteristics; a block of forming the moment of resistance of the turbomechanism; a mod[...]

Estimation of dynamic loads in an electrohydraulic complex at different laws of supply voltage frequency variation DOI:10.15199/48.2017.01.58

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It is shown that direct start of electrohydraulic complex pump units is characterized by essential surges of current, dynamic torque and head. An electrohydraulic complex mathematical model for research of supply voltage frequency variation law influence on transient processes in the system is proposed. It is shown that transient processes behavior in the electrohydraulic complex is influenced by the time of acceleration/braking, pipeline geometry, presence of static head at particular sections of the hydraulic network, the method of the technological mechanism start-up. It is proved that the use of smooth start/stop of the pump unit makes it possible to decrease dynamic loads on the motor, eliminate occurrence of oscillations in the head and flow rate signals, reduce power losses at the start. Basic recommendations as to the choice of the law of input impact generation are formulated. Streszczenie. Wykazano, że bezpośredni start system elektrohydraulicznego charakteryzuje się istotnymi przetężeniami prądowymi oraz dynamicznym momentem. Zaprezentowany został złożony model matematyczny zjawisk elektrohydraulicznych do badania wpływu zasilania napięciowego na procesy przejściowe w systemie. Pokazano, że przebiegi procesów przejściowych w układach elektrohydraulicznych zależą od czasu przyspieszania/hamowania, geometrii rur, obecności statycznej głowicy w poszczególnych sekcjach systemu oraz od metody technologicznej do rozpoczynania procesu, Wykazano, że użycie łagodnego startowania/hamowania pompy czyni możliwym dynamicznego obciążenia silnika, wyeliminować oscylacje głowicy I sygnałów przepływowych, jak również zredukować straty mocy przy starcie, sformułowano podstawowe rekomendacje co do wyboru zasady generacji impulsów wejściowych. (Estymacja obciążeń dynamicznych w systemie elektrohydraulicznym przy różnych zasadach zmiany częstotliwości zasilania napięciowego) Keywords: electrohydraulic complex, transient processes, smooth start/stop, d[...]

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