No abstract

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.

Currently, 78% of all irrigated land in Uzbekistan is provided with water by pumping stations and installations. The water sources of most pumping stations are rivers and irrigation channels that transport a large amount of bottom and suspended sediments. Due to the lack of consideration of bottom sediments moving in the form of ridges, when installing the pumping units suction pipeline, during their operation, these bottom pumps flow from the water intake source in the interior of the units. As a result, intensive waterjet wear of the flow part and the impeller of the pumps occurs. This leads to an intensive reduction in the main parameters of the pumps, as well as reduces their repair period. Currently, this is one of the major problems of pumping stations that take water from the Zarafshan river, as well as those operating on the Karshi, Amu-Bukhara, Amu-Zang and Jizzakh main channels. Laboratory studies were carried out on the experimental installation to determine the height of ridges with different granulometric composition of bottom sediments. As a result, a formula was obtained for determining the height of the ridge, taking into account the heterogeneity of ridge forms. Based on the obtained formula, a method for setting the height of the pumping unit suction pipe inlet relative to the riverbed bottom is recommended. The application of the proposed method does not allow bottom sediments to enter the inner part of the pumps, as a result of which their intensive abrasive wear decreases, the inter-repair period increases, while maintaining its main parameters for a long time.

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.

Currently, the control and accounting of electricity at 1693 irrigation pumping stations of the Ministry of water management of Uzbekistan is carried out manually, on the basis of which 17 different types of documentation are filled in. This work requires a large amount of time and human resources. This can also be observed at the water and wastewater pumping stations. In this paper, the existing system of accounting for electricity consumption is fully considered on the example of several irrigation pumping stations and one regional management of pumping stations. The organizational structure and the procedure for maintaining documents on accounting and collecting information about the electricity consumed by pumping stations were analyzed. Based on the data obtained, an automated system for monitoring and accounting of electric power at pumping stations has been developed. This system eliminates unauthorized switching on pumping units, theft, or inefficient power consumption. As a result, it reduces the annual electricity consumption of pumping stations, and also reduces labor costs. The payback period for the introduction of an automated system for monitoring and accounting of electric power at pumping stations is 2.5 months.