Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Roman MANKO"

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[...]

The use of the wavelet-analysis for the research of the unsteady processes in the pipeline network of a pumping complex DOI:10.15199/48.2019.05.09

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Unsteady processes sometimes occur during the operation of pumping complexes (PC) because of frequent switching on/off of the pump units, alteration of the consumer’s operation mode, non-observance of the tempo of shutting the pipeline valves in the hydraulic network. Such unsteady processes include head pulsation, water hammer, leakage, cavitational self-oscillations, etc. Complex wave processes of different amplitude and frequency accompany their appearance and in some cases may result in the damage of the pumping and pipeline equipment. To identify PC unsteady modes there are a number of methods based on the continuous or periodical monitoring of the parameters of liquid pumping, the frequency analysis of the signals of the head or discharge, etc. [1]. Recently, engineers have often been using wavelet analysis for the diagnostics of various unsteady processes, which proved to be successful in the problems of diagnosis of damages in electric machines and gas turbine engines, the study of the properties of turbulent fields, etc [2]. In comparison with the Fourier transform, the wavelet analysis makes it possible to assess the unsteady processes by the analysis coefficients more accurately and to follow the alteration of the signal frequency properties in the time domain. In this case both a periodic and a non-periodic time function can be considered an analyzed signal. That is why the problem of the research of the wave processes in the pipeline network in unsteady operation modes of a pumping complex with the use of wavelet analysis is of interest. Research method Taking into account the above said, we propose a PC mathematical model including a frequency converter (FC); an induction motor (IM) in u,v,0-coordinates; a centrifugal pump; a block generating a moment of resistance created by the pump; a pipeline network represented by n-number of sections in the form of RLC-circuits; a consumer model with input hydraul[...]

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