Irrigation pumping stations are one of the main elements of irrigation systems and the main consumer of electricity in the agricultural sector of the Republic of Uzbekistan. Therefore, the question of choosing a method for regulating the operation of pumping units is very important. Most irrigation pumping stations in the Republic of Uzbekistan are equipped with centrifugal pumps of type “D”. The main types of regulation for such pumps are: impeller trimming, changing the frequency of rotation of the impeller, the pumping unit switching on and off control method. The specific features of the operating modes of irrigation pumping stations revealed are. The analysis of various methods for regulating pumping units during the operation of irrigation pumping stations showed that, according to the degree of coverage of the water consumption schedule, the most optimal methods are valve control and a change in the rotational speed of the impeller shaft. Regulation by changing the speed of rotation and the pumping unit switching on and off control method more suitable according to the economy criterion. Calculations for the pumping stations “Ulugbek II”, “Kizil-Bayrak”, “Ittifok”, “Navoi” and “Turkiston” showed that with a change in the diameter of the impeller, the energy savings can reach 21.1-63.5%. When using a frequency converter at the same pumping stations, energy savings can reach 16.5-35.4 5%. It must be taken into account that, when turning, regulation is possible only in the direction of decreasing parameters.
This paper gives the results of the investigation of the operation of a pumping unit equipped with a frequency converter. As a rule, it is widely assumed that when changing the speed up to 50 %, the pump efficiency almost does not change, and the possibility of decrease of its efficiency is not taken into consideration when calculating the economic efficiency of the operation of the pumping unit equipped with a frequency converter. However, failure to take account the efficiency decrease may cause inaccurate assessment of the economic efficiency of the use of the frequency converter and, consequently, improper selection of the method of control of the operation of the pumping units. This is particularly important for irrigation pumping plants the operation of which is characterized by large volume of the pumpable volume and less severe requirements for provision of the water pressure required for the consumer. The purpose of this paper is to carry out experiments on a test-bed equipped with a pumping unit, parameter measuring instrument, and a frequency converter, and detection of the pattern of efficiency variation with speed. The paper presents the results of the carried out experiments, the obtained characteristic curves of the variation of different types of the efficiency at variation of the pump shaft speed, as well as their analysis.
It is generally agreed that when using the frequency converter at pumping stations, the economic effect of its use far exceeds the losses in efficiency, and naturally, no comparison between the alternative methods of regulation is given. But, as a practice has shown at the application of the given control method, losses in efficiency can be essential. Quantitatively these losses depend on many factors (degree of regulation, type of the applied frequency converter, pumps and the driving electric motor, operating modes etc.). Therefore, for an accurate assessment of the efficiency of the control method, field tests of the unit with a frequency converter are necessary. Full-scale tests were carried out at the Teshik-Tash-1 pumping station located in the Andijan region of the Republic of Uzbekistan. The field tests consisted of determining the efficiency of the pump unit when the drive shaft speed changes. Graphical dependencies of changes in the energy parameters of the pump unit when changing the rotation frequency of the impeller shaft using a frequency converter are obtained. Tests have shown that loss values can reach significant values when using a frequency converter. If you reduce the speed of the pump impeller by 10 %, the efficiency of the electric drive (motor and converter) will also decrease by 10 %, and if you change it by 25 %, the efficiency of the electric drive may decrease by up to 40 %. The test results can be applied in the selection and feasibility study of the regulation method at irrigation pumping stations equipped with pumps of type D.
In this article we consider the results of studying the problems and prospects of using information technologies to ensure the introduction of new innovative approaches in hydroecology and hydropower, the creation of GIS (GIS-geographic information systems) for hydroecological and hydro-technical monitoring, and also as a visual material for students studying the use of information systems in the development of environmentally acceptable modes of operation of hydraulic structures. The article was devoted to an actual theme - GIS-systems creation for hydro ecological monitoring as tool for support the information systems of the Aral Sea basin and optimisation models at development of ecologically applicable modes of exploitation of hydro technical buildings. It is possible and useful to use association of outputs from various scientific researches in one GIS-database as universal tool for modeling. As example of such approach can be consider as one interconnected system which combination results of work: - System of water-salt balances in all rivers of Uzbekistan. - System of digital maps and schemes that can be used in the development of environmentally acceptable modes of operation of hydraulic and hydropower facilities in Uzbekistan. - The Aral Sea basin monitoring systems (ASBMS) as a digital system of hydroecological monitoring of quality of surface waters on basis ArcView.
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