Method for calculating diameter ratio of single-runner pelton turbine

Abstract

The invention relates to the field of hydroelectric station pelton turbines, discloses a single-runner pelton turbine diameter ratio calculation method, and solves the problems that in the prior art, a single-runner pelton turbine diameter ratio calculation scheme is inaccurate in calculation, large in deviation from an actual value and low in calculation cost. And the water-power engineering construction requirement of a new device with a single-rotating-wheel water bucket type water-turbine generator set cannot be met. According to the method, data of a large number of well-operated single-runner pelton water turbine generator sets at home and abroad are collected and arranged, and then a complex relation among the data is fitted by adopting a nonlinear regression method, so that a new diameter ratio calculation formula of the single-runner pelton water turbine is obtained; the diameter ratio of the single-runner pelton turbine can be quickly and accurately calculated by substituting the rated specific speed value of a single nozzle of the single-runner pelton turbine with the diameter ratio to be calculated into a new diameter ratio calculation formula of the single-runner pelton turbine.

Description

Technical Field

[0001] This invention relates to the field of bucket turbines in hydropower stations, and specifically to a method for calculating the diameter ratio of a single-runner bucket turbine. Background Technology

[0002] As the core equipment of a hydropower station that converts the mechanical energy of water flow into the mechanical energy of the turbine, the turbine is known as the "heart" of the hydropower station. The reasonable selection of its parameters is directly related to the initial investment scale of the hydropower project and the economic benefits of the power plant after commissioning. It is one of the core contents that need to be studied in the construction of hydropower projects.

[0003] Among the key technical parameters of a single-runner bucket turbine, the diameter ratio (i.e., the nominal diameter of the runner) is... With nozzle jet diameter ratio The efficiency, operational stability, and bucket root strength of a turbine are important comprehensive indicators for measuring unit performance. Their values ​​have a significant impact on turbine efficiency, operational stability, and bucket root strength. Within a certain range, the larger the diameter ratio, the higher the turbine efficiency and the better the operational stability. However, if the diameter ratio is too large, it will lead to a decrease in unit speed and an increase in the nominal diameter of the runner, which in turn increases wind loss and reduces efficiency. At the same time, it will increase the weight of the unit, the size of the unit and the plant, increase investment costs, and reduce economic efficiency. If the diameter ratio is too small, it will easily cause safety hazards such as cracks or even bucket breakage due to insufficient number of buckets and weak root strength.

[0004] Therefore, how to achieve the nominal diameter of the runner With nozzle jet diameter A proper match makes the diameter ratio Achieving optimal performance has become a key research topic in the construction of hydropower projects related to single-rotor bucket turbine generator units.

[0005] In existing technologies, the calculation of the diameter ratio of a single-runner bucket turbine mainly relies on traditional estimation formulas, such as... This formula is based on statistical data of hydro-turbines from before the 1990s. It does not incorporate the large amount of data on new hydro-turbines accumulated during the nearly 30 years of large-scale hydropower development, nor does it consider the impact of the development of new technologies, materials, processes, and structures on the research and operation of hydro-turbines. Therefore, it has significant limitations due to its historical context. In practical applications, the diameter ratio calculated using this formula deviates significantly from the actual data of units put into operation in recent years, and it can no longer meet the construction needs of hydropower projects related to new single-runner bucket turbine generator units. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for calculating the diameter ratio of a single-runner bucket turbine, which solves the problem that the calculation scheme of the diameter ratio of a single-runner bucket turbine in the prior art is inaccurate, has a large deviation from the actual value, and cannot meet the construction needs of hydropower projects with new devices including single-runner bucket turbine generator sets.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: The method for calculating the diameter ratio of a single-runner bucket turbine includes the following steps: S1. Collect and organize data on single-runner bucket turbine generator sets that have been put into operation at home and abroad, and establish a basic database of single-runner bucket turbine parameter samples. The parameter samples in the database include: rated power, rated head, rated speed, number of nozzles, rated specific speed of a single nozzle, nominal diameter of the runner, nozzle jet diameter and diameter ratio. The formula for calculating the rated specific speed of a single nozzle is as follows: ; in, The rated specific speed of a single nozzle of a water turbine, in m·kW; This refers to the rated speed of the water turbine, expressed in r / min. This refers to the rated power of the water turbine, measured in kW. This refers to the number of nozzles in the water turbine, expressed in units. The rated head of the water turbine is expressed in meters (m). S2. Based on the data in the parameter sample database of the single-runner bucket turbine, a nonlinear regression method is used to fit the relationship between the diameter ratio and the rated specific speed of a single nozzle, and the calculation formula for the diameter ratio of the single-runner bucket turbine is obtained: ; in, The ratio of turbine diameters is a dimensionless quantity. The rated specific speed of a single nozzle of a water turbine, in m·kW; S3. For a single-runner bucket turbine whose diameter ratio needs to be calculated, substitute its rated speed, rated power, number of nozzles and rated head into the calculation formula for the rated specific speed of a single nozzle to obtain the rated specific speed value of the single nozzle of the turbine. S4. Substitute the single nozzle rated specific speed value obtained in step S3 into the diameter ratio calculation formula obtained in step S2 to calculate the diameter ratio of the single-runner bucket turbine to be calculated.

[0008] Furthermore, in step S2, the method of fitting the relationship between the diameter ratio and the rated specific speed of a single nozzle using a nonlinear regression method includes: using the rated specific speed of a single nozzle as the independent variable and the diameter ratio as the dependent variable, and using a nonlinear regression method to fit the data of the rated specific speed and diameter ratio of a single nozzle in the basic database of parameters of a single-runner bucket turbine.

[0009] The beneficial effects of this invention are: (1) By collecting and organizing a large amount of data on well-functioning single-runner bucket turbine generator sets at home and abroad, this invention has established a comprehensive, complete and effective basic database of single-runner bucket turbine parameter samples, which provides solid data support for the derivation of the subsequent diameter ratio calculation formula.

[0010] (2) Using the data in the above database, a new formula for calculating the diameter ratio of a single-runner bucket turbine was obtained by fitting the data using a nonlinear regression method. This formula fully incorporates a large amount of data on single-runner bucket turbines accumulated in the large-scale hydropower development over the past 30 years, takes into account the impact of the development of new technologies, new materials, new processes and new structures on the research and operation of turbines, and overcomes the limitations of the existing estimation formulas based on data from before the 1990s.

[0011] (3) The diameter ratio obtained by the calculation method of the present invention has a small deviation from the actual value and high calculation accuracy. It can quickly and reasonably match the nominal diameter of the runner and the nozzle jet diameter of the single-runner bucket turbine, so that the diameter ratio reaches the optimal value.

[0012] (4) This method improves the quality and efficiency of demonstration and development of single-runner bucket turbines, reduces costs, and can better meet the construction needs of hydropower projects with new equipment having single-runner bucket turbine generator sets. It provides strong technical support for the construction of similar hydropower projects at home and abroad and the efficient and stable operation of single-runner bucket turbine generator sets after commissioning. Attached Figure Description

[0013] Figure 1 This is a flowchart of the method for calculating the diameter ratio of a single-runner bucket turbine in this invention. Detailed Implementation

[0014] This invention aims to provide a method for calculating the diameter ratio of a single-runner bucket turbine, addressing the problems of inaccurate calculations and significant deviations from actual values ​​in existing methods, which fail to meet the needs of hydropower projects with new installations featuring single-runner bucket turbine generator sets. The core idea is to collect and organize extensive data on well-performing single-runner bucket turbine generator sets from both domestic and international sources, including rated power, rated head, rated speed, number of nozzles, rated specific speed per nozzle, nominal runner diameter, nozzle jet diameter, and diameter ratio. Then, a nonlinear regression method is used to fit the complex relationships between these data, thereby obtaining a new formula for calculating the diameter ratio of a single-runner bucket turbine. In practical applications, by substituting the rated specific speed per nozzle of the single-runner bucket turbine into the new formula, the diameter ratio of the single-runner bucket turbine can be calculated quickly and accurately.

[0015] In practical implementation, the implementation process of the single-runner bucket turbine diameter ratio calculation method in this invention is as follows: Figure 1 It includes the following steps: S1. Collect and organize parameter data for single-runner bucket turbines, and establish a parameter sample database: In this step, we collect and organize a large amount of data on well-functioning single-runner bucket turbine generator sets from both domestic and international sources, establishing a comprehensive, complete, and effective basic database of single-runner bucket turbine parameter samples. The turbine parameter data collected here mainly includes the name / country of the hydropower station, rated power, rated head, rated speed, number of nozzles, rated specific speed per nozzle, nominal runner diameter, nozzle jet diameter and diameter ratio, etc.

[0016] S2. Based on sample parameters, a new formula for calculating the diameter ratio of a single-runner bucket turbine is obtained using a nonlinear regression method: In this step, based on the data in the basic database of single-runner bucket turbine parameter samples, a nonlinear regression method is used to obtain a new formula for calculating the diameter ratio of a single-runner bucket turbine. That is, the nonlinear regression method is used to fit the complex relationship between the turbine diameter ratio and the rated specific speed of a single nozzle in the basic database of single-runner bucket turbine parameter samples, thereby obtaining a new formula for calculating the diameter ratio of a single-runner bucket turbine.

[0017] S3. Calculate the rated specific speed of a single nozzle of the single-runner bucket turbine using the formula for calculating the rated specific speed of a single nozzle: In this step, for a single-runner bucket turbine whose diameter ratio is to be calculated, the formula for calculating the rated specific speed of a single nozzle of the turbine is used. The rated speed, rated power, number of nozzles, and rated head of the single-runner bucket turbine whose diameter ratio is to be calculated are substituted into the formula to calculate the rated specific speed of a single nozzle of the single-runner bucket turbine.

[0018] S4. Calculate the diameter ratio of the single-runner bucket turbine using the new diameter ratio calculation formula: In this step, for the single-runner bucket turbine whose diameter ratio needs to be calculated, the new diameter ratio calculation formula for the single-runner bucket turbine obtained in step S2 is used. By substituting the rated specific speed of a single nozzle of the single-runner bucket turbine whose diameter ratio needs to be calculated, the diameter ratio of the single-runner bucket turbine can be calculated quickly and accurately.

[0019] This embodiment takes the calculation of the diameter ratio of a single-runner bucket turbine as an example, and the implementation process is as follows: (1) First, by collecting and organizing a large amount of data on well-functioning single-runner bucket turbine generator sets at home and abroad, a comprehensive, complete and effective basic database of single-runner bucket turbine parameter samples was established. Some of the parameter samples in the database are shown in Table 1.

[0020] Table 1. Sample table of partial parameters from the basic database of single-runner bucket turbine parameters. (2) Next, based on the parameter samples in the basic database of single-runner bucket turbine parameters, the relationship between the diameter ratio of the single-runner bucket turbine and the rated specific speed of the single nozzle is fitted using a nonlinear regression method, and a new formula for calculating the diameter ratio of the single-runner bucket turbine is obtained: (1) (3) Then, for the single-runner bucket turbine whose diameter ratio is to be calculated, substitute its rated speed, rated power, number of nozzles and rated head into the calculation formula of the rated specific speed of a single nozzle, and calculate the rated specific speed of a single nozzle of the single-runner bucket turbine.

[0021] (4) Finally, for the single-runner bucket turbine whose diameter ratio is to be calculated, substitute its single-nozzle rated specific speed value into the new diameter ratio calculation formula of the single-runner bucket turbine, and the diameter ratio of the single-runner bucket turbine can be calculated.

[0022] To verify the accuracy of the new diameter ratio calculation formula for the single-runner bucket turbine proposed in this embodiment, the rated specific speed of the single nozzle in Table 1 above will be substituted into the new diameter ratio calculation formula for the single-runner bucket turbine proposed in this embodiment and the diameter ratio estimation formula for the single-runner bucket turbine used in the conventional technology, respectively, to calculate the diameter ratio of the single-runner bucket turbine, and the error rate between the calculated and actual diameter ratio values ​​will be compared.

[0023] The formula for estimating the diameter ratio of a single-runner bucket turbine in traditional technology is as follows: (2) The calculation results of the diameter ratio of a single-runner bucket turbine using the above formula (1) provided in this embodiment and the above formula (2) provided in the conventional technology are shown in Table 2.

[0024] Table 2 Comparison of the calculation results of the diameter ratio of a single-runner bucket turbine using formula (1) and formula (2) Based on the calculation results in Table 2 above, it can be seen that: The error rate of the calculated value of formula (1) in this embodiment is small, only -3.774% to 2.032%, and the calculation accuracy meets the requirements of engineering calculation. This shows that formula (1) can be used to calculate the diameter ratio of a single-runner bucket turbine, which can better meet the construction needs of hydropower projects with new equipment including single-runner bucket turbine generator sets. In contrast, the error rate of the calculated value of the estimation formula (2) used in traditional technology is -6.918% to 2.584%, and the calculation accuracy cannot meet the requirements of engineering calculation.

[0025] Although embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, and all such changes and alterations shall not depart from the protection scope of the present invention.

Claims

1. A method for calculating the diameter ratio of a single-runner bucket turbine, characterized in that, Includes the following steps: S1. Collect and organize data on single-runner bucket turbine generator sets that have been put into operation at home and abroad, and establish a basic database of single-runner bucket turbine parameter samples. The parameter samples in the database include: rated power, rated head, rated speed, number of nozzles, rated specific speed of a single nozzle, nominal diameter of the runner, nozzle jet diameter and diameter ratio. The formula for calculating the rated specific speed of a single nozzle is as follows: ； in, The rated specific speed of a single nozzle of a water turbine, in m·kW; This refers to the rated speed of the water turbine, expressed in r / min. This refers to the rated power of the water turbine, measured in kW. This refers to the number of nozzles in the water turbine, expressed in units. The rated head of the water turbine is expressed in meters (m). S2. Based on the data in the parameter sample database of the single-runner bucket turbine, a nonlinear regression method is used to fit the relationship between the diameter ratio and the rated specific speed of a single nozzle, and the calculation formula for the diameter ratio of the single-runner bucket turbine is obtained: ； in, The ratio of turbine diameters is a dimensionless quantity. The rated specific speed of a single nozzle of a water turbine, in m·kW; S3. For a single-runner bucket turbine whose diameter ratio needs to be calculated, substitute its rated speed, rated power, number of nozzles and rated head into the calculation formula for the rated specific speed of a single nozzle to obtain the rated specific speed value of the single nozzle of the turbine. S4. Substitute the single nozzle rated specific speed value obtained in step S3 into the diameter ratio calculation formula obtained in step S2 to calculate the diameter ratio of the single-runner bucket turbine to be calculated.

2. The method for calculating the diameter ratio of a single-runner bucket turbine as described in claim 1, characterized in that, In step S2, the method of fitting the relationship between the diameter ratio and the rated specific speed of a single nozzle using a nonlinear regression method includes: using the rated specific speed of a single nozzle as the independent variable and the diameter ratio as the dependent variable, and using the rated specific speed and diameter ratio data of a single nozzle in the basic database of single-runner bucket turbine parameter samples to fit the data using a nonlinear regression method.

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