Method for determining cavitation coefficient of power station based on mixed-flow reversible pumped storage unit

Abstract

The invention relates to the technical field of pumped storage engineering, and discloses a method for determining a power station cavitation coefficient based on a mixed-flow reversible pumped storage unit, which comprises the following steps of: adjusting a first corresponding relation between a primary cavitation coefficient and a specific speed to generate a second corresponding relation; generating a third corresponding relation according to the determined safety coefficient parameter and the second corresponding relation; obtaining first and second power station cavitation coefficient parameters according to the first and second specific speed parameters and a third corresponding relation; adjusting a first suction height and a second suction height generated according to the first lift parameter, the second lift parameter, the first power station cavitation coefficient parameter and the second power station cavitation coefficient parameter; obtaining a third suction height and a fourth suction height; according to the third suction height, the fourth suction height, the first lift parameter and the second lift parameter, the first target power station cavitation coefficient and the second target power station cavitation coefficient are obtained, the power station cavitation coefficient is determined through the accurate suction height, and the accuracy of the power station cavitation coefficient is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of pumped storage power engineering, and particularly relates to a method for determining the station cavitation coefficient of a mixed-flow reversible pumped storage unit power station. Background Art

[0002] The cavitation characteristics of a pump-turbine have an important impact on the operating performance, efficiency, safety, and lifespan of the pump-turbine. At the same time, the cavitation characteristics of the pump-turbine are also one of the key factors affecting the suction height and installation elevation of the power station unit. In the early stage of the construction of a pumped storage power station, it is often necessary to basically determine the layout of the underground powerhouse hub without determining the manufacturer of the pumped storage unit. Therefore, the selection of the suction height and installation elevation of the pumped storage unit is particularly important. As a key factor affecting the suction height and installation elevation, the determination of the cavitation characteristics of the pump-turbine is also very important.

[0003] Currently, the methods for determining the station cavitation coefficient of the pump-turbine of a pumped storage power station include: using the data of existing pump-turbines with similar water heads and similar rotational speeds to generate the station cavitation coefficient. However, the characteristic water heads and specific speeds of pump-turbines in different pumped storage power stations vary greatly, resulting in the problem that the obtained station cavitation coefficient is not accurate enough and cannot more accurately reflect the true level of the cavitation performance of the pump-turbine of the pumped storage power station. Summary of the Invention

[0004] In view of this, the present invention provides a method for determining the station cavitation coefficient of a mixed-flow reversible pumped storage unit, so as to solve the problem that the station cavitation coefficient obtained by the method for determining the station cavitation coefficient of the pump-turbine of a pumped storage power station in the related art is not accurate enough.

[0005] In a first aspect, the present invention provides a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station, comprising: obtaining a first correspondence relationship between the initial cavitation coefficient and the specific speed of a pump-turbine in different head sections of a mixed-flow reversible pumped-storage unit power station, and adjusting the first correspondence relationship to generate a second correspondence relationship between the power station cavitation coefficient, the safety factor, and the specific speed; the initial cavitation coefficient is the cavitation coefficient when cavitation begins to occur in the pump-turbine; the power station cavitation coefficient is used to evaluate the cavitation performance of the pump-turbine; generating a safety factor parameter according to historical power station cavitation coefficient parameters, historical specific speed parameters, and the second correspondence relationship, so as to generate a third correspondence relationship between the power station cavitation coefficient and the specific speed according to the safety factor parameter and the second correspondence relationship; obtaining a first power station cavitation coefficient parameter corresponding to the first head and a second power station cavitation coefficient parameter corresponding to the second head according to the first specific speed parameter corresponding to the first head, the second specific speed parameter corresponding to the second head, and the third correspondence relationship; the pump lift height corresponding to the first head is greater than the pump lift height corresponding to the first head; generating a first suction height corresponding to the first head and a second suction height corresponding to the second head according to the first head parameter, the second head parameter, the first power station cavitation coefficient parameter, and the second power station cavitation coefficient parameter; adjusting the first suction height to obtain a third suction height; adjusting the second suction height to obtain a fourth suction height; obtaining a first target power station cavitation coefficient corresponding to the first head and a second target power station cavitation coefficient corresponding to the second head according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter.

[0006] The present invention obtains the first correspondence relationship between the initial cavitation coefficient and the specific speed of a pump-turbine at different head sections, and adjusts the first correspondence relationship by adding a safety factor thereto to generate a second correspondence relationship. The present invention adjusts the first correspondence relationship according to the safety factor, comprehensively considering the parameters related to the cavitation performance, and can more accurately and comprehensively determine the cavitation coefficient of a power station. The present invention generates a safety factor parameter according to the historical power station cavitation coefficient parameter, the historical specific speed parameter, and the second correspondence relationship, and generates a third correspondence relationship between the power station cavitation coefficient and the specific speed according to the safety factor parameter and the second correspondence relationship. Using historical data makes the setting of the safety factor more scientific and makes the correspondence relationship between the power station cavitation coefficient and the specific speed more reasonable. The present invention obtains the power station cavitation coefficient parameter according to different head specific speed parameters and the third correspondence relationship, accurately obtains the corresponding power station cavitation coefficient parameter for different heads, and provides an accurate parameter basis for the operation of the power station. The present invention determines the suction height corresponding to different heads by combining the head parameter and the power station cavitation coefficient parameter. Since there are many factors to be considered for the suction height, the suction height determined by combining the head parameter and the power station cavitation coefficient parameter is not accurate enough. The present invention adjusts the suction height to ensure the accuracy of the suction height. The present invention back-calculates the first target power station cavitation coefficient and the second target power station cavitation coefficient according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter. Since the third suction height and the fourth suction height of the present invention are relatively accurate, the accuracy of the first target power station cavitation coefficient and the second target power station cavitation coefficient determined according to the third suction height and the fourth suction height is relatively high, which conforms to the power station cavitation coefficient under actual conditions.

[0007] In an alternative embodiment, obtaining the first correspondence relationship between the initial cavitation coefficient and the specific speed of a pump-turbine at different head sections of a mixed-flow reversible pumped-storage unit power station includes: obtaining the historical initial cavitation coefficient parameter and the historical specific speed parameter of the pump-turbine at different head sections of the mixed-flow reversible pumped-storage unit power station; presetting that there is a power function relationship between the historical initial cavitation coefficient parameter and the historical specific speed parameter to obtain a preset power function expression; performing a logarithmic transformation on the preset power function expression to convert the preset power function expression into a linear model; estimating the parameters in the linear model to obtain parameter estimation values; and restoring the preset power function expression according to the parameter estimation values to obtain the first correspondence relationship between the initial cavitation coefficient and the specific speed.

[0008] The present invention flexibly fits the complex relationship between the initial cavitation coefficient and the specific speed through a preset power function expression, obtains a correspondence relationship that more conforms to the actual operation law of the pump-turbine, and improves the accuracy of the initial cavitation coefficient.

[0009] In an alternative embodiment, adjusting the first correspondence relationship to generate a second correspondence relationship among the plant cavitation coefficient, the safety factor, and the specific speed includes: according to the first correspondence relationship, multiplying the specific speed by the safety factor to obtain the second correspondence relationship among the plant cavitation coefficient, the safety factor, and the specific speed.

[0010] In an alternative embodiment, generating a first suction height corresponding to a first head and a second suction height corresponding to a second head according to a first head parameter, a second head parameter, a first plant cavitation coefficient parameter, and a second plant cavitation coefficient parameter includes: obtaining a first product result according to the product of the first head parameter and the first plant cavitation coefficient parameter; obtaining the first suction height corresponding to the first head according to the difference between a first preset value and the first product result; obtaining a second product result according to the product of the second head parameter and the second plant cavitation coefficient parameter; obtaining the second suction height corresponding to the second head according to the difference between the first preset value and the second product result.

[0011] In an alternative embodiment, adjusting the first suction height to obtain a third suction height; adjusting the second suction height to obtain a fourth suction height includes: obtaining factors affecting the suction height, and adjusting the first suction height according to the factors affecting the suction height to obtain the third suction height; adjusting the second suction height according to the factors affecting the suction height to obtain the fourth suction height.

[0012] In an alternative embodiment, obtaining a first target plant cavitation coefficient corresponding to the first head and a second target plant cavitation coefficient corresponding to the second head according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter includes: obtaining a first difference according to the difference between a first preset value and the first head parameter; obtaining the first target plant cavitation coefficient corresponding to the first head according to the quotient of the first difference and the third suction height; obtaining a second difference according to the difference between the first preset value and the second head parameter; obtaining the second target plant cavitation coefficient corresponding to the second head according to the quotient of the second difference and the fourth suction height. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the related art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0014] Figure 1 is a flowchart of a method for determining the plant cavitation coefficient based on a mixed-flow reversible pumped-storage unit according to an embodiment of the present invention.

[0015] Figure 2 It is a schematic diagram of the corresponding relationship between the specific speed and the safety factor according to an embodiment of the present invention.

[0016] Figure 3 It is a schematic diagram of the first corresponding relationship and the second corresponding relationship according to an embodiment of the present invention.

[0017] Figure 4 It is a schematic flow chart of another method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station according to an embodiment of the present invention.

[0018] Figure 5 It is a schematic flow chart of yet another method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station according to an embodiment of the present invention. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The cavitation characteristics of the pump-turbine in the pumped-storage project have an important impact on the operating performance, efficiency, safety and life of the pump-turbine, and are also one of the key factors affecting the suction height and installation elevation of the pumped-storage power station units. In the initial stage of the construction of the pumped-storage power station, it is often necessary to basically determine the layout of the underground powerhouse hub without determining the manufacturer of the pumped-storage unit. Therefore, the selection of the suction height and installation elevation of the pumped-storage unit is particularly important. As a key factor affecting the suction height and installation elevation of the pumped-storage power station units, the determination of the cavitation characteristics of the pump-turbine is also very important. The cavitation characteristics of the pump-turbine are usually reflected by the cavitation coefficient of the pump-turbine in the power station.

[0021] At present, there are usually two methods for determining the cavitation coefficient of the pumped-storage power station. The first method is to estimate the cavitation coefficient of the power station by using the existing pump-turbine model test data with similar water heads and similar specific speeds. However, the characteristic water heads and the specific speeds of the pump-turbines of different pumped-storage power stations vary greatly, resulting in the problem that the obtained cavitation coefficient of the power station is not accurate enough and cannot more accurately reflect the true level of the cavitation performance of the pump-turbine in the pumped-storage power station. The second method is to estimate the cavitation coefficient of the pumped-storage power station by using a statistical formula. The statistical formula for determining the cavitation coefficient of the current pump-turbine has been established for a long time, and the calculation results cannot accurately reflect the true level of the cavitation performance of the pump-turbine in the pumped-storage power station.

[0022] An embodiment of the present invention provides a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station, which determines the cavitation coefficient of the power station through an accurate suction height, so as to improve the accuracy of the cavitation coefficient of the power station.

[0023] According to an embodiment of the present invention, an embodiment of a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0024] In this embodiment, a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station is provided, which can be used in computer equipment. Figure 1 It is a flowchart of a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station according to an embodiment of the present invention, as Figure 1 shown, the process includes the following steps:

[0025] Step S101, obtain a first correspondence relationship between the initial cavitation coefficient and the specific speed of the pump-turbine in different head sections of the mixed-flow reversible pumped-storage unit power station, and adjust the first correspondence relationship to generate a second correspondence relationship between the cavitation coefficient of the power station, the safety factor, and the specific speed; the initial cavitation coefficient is the cavitation coefficient when cavitation begins to occur in the pump-turbine; the cavitation coefficient of the power station is used to evaluate the cavitation performance of the pump-turbine.

[0026] Among them, the mixed-flow reversible pumped-storage unit power station is a water conservancy power generation facility that uses the electric energy during the low electric load period to pump water to the upper reservoir and then releases water to the lower reservoir for power generation during the high electric load peak period. The head of the pumped-storage power station refers to the water level difference between the upper reservoir and the lower reservoir. Different head sections of the pumped-storage power station can include low head sections, medium head sections, and high head sections. The pump-turbine in the embodiment of the present invention mainly refers to a mixed-flow reversible pump-turbine. The specific speed of the pump-turbine is the rotational speed that the turbine or pump has under the optimal operating conditions of the turbine or the optimal operating conditions of the pump.

[0027] In some optional embodiments, obtaining the first correspondence relationship between the initial cavitation coefficient and the specific speed of the pump-turbine in different head sections of the mixed-flow reversible pumped-storage unit power station includes: using the method of power function regression statistical analysis to statistically analyze the historical initial cavitation coefficient parameters and historical specific speed parameters of the pump-turbine in different head sections of the mixed-flow reversible pumped-storage unit power station, and obtaining the first correspondence relationship between the initial cavitation coefficient and the specific speed.

[0028] Specifically, the implementation process of the power function regression statistical analysis method includes: obtaining the historical initial cavitation coefficient parameters and historical specific speed parameters of the pump-turbine in different head sections of the mixed-flow reversible pumped storage power station; presuming that there is a power function relationship between the historical initial cavitation coefficient parameters and historical specific speed parameters, and obtaining a preset power function expression; performing a logarithmic transformation on the preset power function expression to convert it into a linear model; estimating the parameters in the linear model to obtain parameter estimation values; and restoring the preset power function expression according to the parameter estimation values to obtain the first corresponding relationship between the initial cavitation coefficient and the specific speed.

[0029] Exemplarily, the first corresponding relationship between the initial cavitation coefficient and the specific speed is:

[0030] σ i =10 -3 n q 1.413 ,

[0031] where, σ i is the initial cavitation coefficient, and n q is the specific speed.

[0032] In some optional implementation manners, adjusting the first corresponding relationship to generate the second corresponding relationship among the station cavitation coefficient, the safety factor, and the specific speed includes: introducing the safety factor into the first corresponding relationship to obtain the second corresponding relationship among the station cavitation coefficient, the safety factor, and the specific speed.

[0033] Exemplarily, introducing the safety factor K into the first corresponding relationship, the obtained second corresponding relationship is:

[0034] σ p =K10 -3 n q 1.413 ,

[0035] where, σ p is the station cavitation coefficient, n q is the specific speed, and K is the safety factor.

[0036] Step S102, generating a safety factor parameter according to the historical station cavitation coefficient parameter, the historical specific speed parameter, and the second corresponding relationship, so as to generate a third corresponding relationship between the station cavitation coefficient and the specific speed according to the safety factor parameter and the second corresponding relationship.

[0037] In some optional implementation manners, generating a safety factor parameter according to the historical station cavitation coefficient parameter, the historical specific speed parameter, and the second corresponding relationship includes: substituting the historical station cavitation coefficient parameter and the historical specific speed parameter into the second corresponding relationship to obtain the safety factor parameter.

[0038] In some alternative embodiments, generating a third correspondence relationship between the plant cavitation coefficient and the specific speed according to the safety factor parameter and the second correspondence relationship includes: substituting the safety factor parameter into the second correspondence relationship to generate the third correspondence relationship between the plant cavitation coefficient and the specific speed.

[0039] In some alternative embodiments, generating a third correspondence relationship between the plant cavitation coefficient and the specific speed according to the safety factor parameter and the second correspondence relationship further includes: performing power function regression statistical analysis on the safety factor parameter and the historical specific speed parameter to obtain the correspondence relationship between the safety factor and the specific speed; combining the correspondence relationship between the safety factor and the specific speed with the second correspondence relationship to obtain the third correspondence relationship.

[0040] Exemplarily, as Figure 2 shown, it is a schematic diagram of the correspondence relationship between the specific speed and the safety factor. The abscissa is the pump specific speed n q , with the unit of m·m3 / s (meter multiplied by cubic meter per second), and the ordinate is the safety factor K. By performing power function regression statistical analysis on the specific speed and the safety factor, the correspondence relationship between the safety factor and the specific speed is obtained as:

[0041] K = 3.55n q -0.29 ,

[0042] where K is the safety factor and n q is the specific speed.

[0043] In some alternative embodiments, combining the correspondence relationship between the safety factor and the specific speed with the second correspondence relationship to obtain the third correspondence relationship includes: substituting the correspondence relationship between the safety factor and the specific speed into the second correspondence relationship to obtain the third correspondence relationship.

[0044] Exemplarily, as Figure 3 shown, it is a schematic diagram of the first correspondence relationship and the second correspondence relationship. The abscissa is the pump operating condition specific speed, and the ordinate is the pump operating condition incipient cavitation coefficient. With different values of the safety factor K, the trend lines of the plant cavitation coefficient are different, and the expression of the third correspondence relationship is obtained as:

[0045] σ p = 0.00355n q 1.123 ,

[0046] where σ p is the plant cavitation coefficient and n q is the specific speed.

[0047] Step S103: Obtain the first power station cavitation coefficient parameter corresponding to the first head and the second power station cavitation coefficient parameter corresponding to the second head according to the first specific speed parameter corresponding to the first head, the second specific speed parameter corresponding to the second head, and the third correspondence; the water-lifting height of the water pump corresponding to the first head is greater than the water-lifting height of the water pump corresponding to the first head.

[0048] Among them, the head is the energy increment obtained by the pump-turbine to lift water from a low place to a high place per unit weight of water flow, usually represented by the water-lifting height. The first head is the maximum head of the pump-turbine, and the second head is the minimum head of the pump-turbine.

[0049] In some alternative embodiments, substitute the first specific speed parameter corresponding to the first head into the third correspondence to obtain the first power station cavitation coefficient parameter corresponding to the first head; substitute the second specific speed parameter corresponding to the second head into the third correspondence to obtain the second power station cavitation coefficient parameter corresponding to the second head.

[0050] Step S104: Generate the first suction height corresponding to the first head and the second suction height corresponding to the second head according to the first head parameter, the second head parameter, the first power station cavitation coefficient parameter, and the second power station cavitation coefficient parameter.

[0051] In some alternative embodiments, generating the first suction height corresponding to the first head and the second suction height corresponding to the second head according to the first head parameter, the second head parameter, the first power station cavitation coefficient parameter, and the second power station cavitation coefficient parameter includes: obtaining a first product result according to the product of the first head parameter and the first power station cavitation coefficient parameter; obtaining the first suction height corresponding to the first head according to the difference between the first preset value and the first product result; obtaining a second product result according to the product of the second head parameter and the second power station cavitation coefficient parameter; obtaining the second suction height corresponding to the second head according to the difference between the first preset value and the second product result.

[0052] Among them, the first preset value can be 9.5.

[0053] Exemplarily, the formula for determining the suction height is:

[0054] H s =9.5 - σ p *H p ,

[0055] Among them, H s is the suction height, σ p is the power station cavitation coefficient parameter, and H p is the head parameter.

[0056] Step S105: Adjust the first suction height to obtain the third suction height; adjust the second suction height to obtain the fourth suction height.

[0057] In some alternative embodiments, adjusting the first suction height to obtain the third suction height and adjusting the second suction height to obtain the fourth suction height includes: obtaining factors affecting the suction height, and adjusting the first suction height according to the factors affecting the suction height to obtain the third suction height; adjusting the second suction height according to the factors affecting the suction height to obtain the fourth suction height.

[0058] Among them, the factors affecting the suction height include factors such as the environment, historical data, and terrain of the pumped-storage power station.

[0059] In some alternative embodiments, raise or lower the first suction height according to the factors affecting the suction height to obtain the third suction height, and raise or lower the second suction height according to the factors affecting the suction height to obtain the fourth suction height.

[0060] In some alternative embodiments, form an influence factor according to the factors affecting the suction height, and adjust the first suction height according to the influence factor to obtain the third suction height; adjust the second suction height according to the influence factor to obtain the fourth suction height.

[0061] Specifically, obtain the third suction height according to the product of the influence factor and the first suction height; obtain the fourth suction height according to the product of the influence factor and the second suction height.

[0062] Step S106: Obtain the first target station cavitation coefficient corresponding to the first head and the second target station cavitation coefficient corresponding to the second head according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter.

[0063] In some alternative embodiments, obtaining the first target station cavitation coefficient corresponding to the first head and the second target station cavitation coefficient corresponding to the second head according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter includes: obtaining a first difference according to the difference between the first preset value and the first head parameter; obtaining the first target station cavitation coefficient corresponding to the first head according to the quotient of the first difference and the third suction height; obtaining a second difference according to the difference between the first preset value and the second head parameter; obtaining the second target station cavitation coefficient corresponding to the second head according to the quotient of the second difference and the fourth suction height.

[0064] Exemplarily, substitute the third suction height and the first head parameter into the formula for determining the suction height in step S104 above to obtain the first target station cavitation coefficient, that is, the station cavitation coefficient corresponding to the maximum head; substitute the fourth suction height and the second head parameter into the formula for determining the suction height in step S104 above to obtain the second target station cavitation coefficient, that is, the station cavitation coefficient corresponding to the minimum head.

[0065] In some alternative embodiments, the method for determining the station cavitation coefficient of a mixed-flow reversible pumped-storage unit further includes: comparing the first target station cavitation coefficient with the incipient cavitation coefficient parameter. When the first target station cavitation coefficient is greater than the incipient cavitation coefficient parameter, generate a first prompt message, where the first prompt message is used to prompt that no adjustment of the third suction height is required. When the first target station cavitation coefficient is less than or equal to the incipient cavitation coefficient parameter, adjust the third suction height (which can be to increase the third suction height), and return to the step of obtaining the first target station cavitation coefficient corresponding to the first head according to the third suction height and the first head parameter until the first target station cavitation coefficient is greater than the incipient cavitation coefficient parameter; compare the second target station cavitation coefficient with the incipient cavitation coefficient parameter. When the second target station cavitation coefficient is greater than the incipient cavitation coefficient parameter, generate a second prompt message, where the second prompt message is used to prompt that no adjustment of the fourth suction height is required. When the second target station cavitation coefficient is less than or equal to the incipient cavitation coefficient parameter, adjust the fourth suction height (which can be to increase the fourth suction height), and return to the step of obtaining the second target station cavitation coefficient corresponding to the second head according to the fourth suction height and the second head parameter until the second target station cavitation coefficient is greater than the incipient cavitation coefficient parameter.

[0066] The method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station provided in this embodiment obtains the first correspondence between the initial cavitation coefficient and the specific speed of the pump-turbine in different head sections, and adjusts the first correspondence, adding a safety factor to the first correspondence to generate a second correspondence. The embodiment of the present invention adjusts the first correspondence according to the safety factor, comprehensively considering the parameters related to cavitation performance, and can determine the cavitation coefficient of the power station more accurately and comprehensively. The embodiment of the present invention generates a safety factor parameter according to the historical power station cavitation coefficient parameter, the historical specific speed parameter, and the second correspondence, and generates a third correspondence between the power station cavitation coefficient and the specific speed according to the safety factor parameter and the second correspondence. Using historical data makes the setting of the safety factor more scientific and makes the correspondence between the power station cavitation coefficient and the specific speed more reasonable. The embodiment of the present invention obtains the power station cavitation coefficient parameter according to the different head specific speed parameters and the third correspondence, and accurately obtains the corresponding power station cavitation coefficient parameter for different heads, providing an accurate parameter basis for the operation of the power station. The embodiment of the present invention combines the head parameter and the power station cavitation coefficient parameter to determine the suction height corresponding to different heads. Since there are many factors to be considered for the suction height, the suction height determined by combining the head parameter and the power station cavitation coefficient parameter is not accurate enough. The present invention adjusts the suction height to ensure the accuracy of the suction height. The embodiment of the present invention back-calculates the first target power station cavitation coefficient and the second target power station cavitation coefficient according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter. Since the third suction height and the fourth suction height of the present invention are relatively accurate, the accuracy of the first target power station cavitation coefficient and the second target power station cavitation coefficient determined according to the third suction height and the fourth suction height is relatively high, which conforms to the power station cavitation coefficient under actual conditions.

[0067] In this embodiment, a method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station is provided, which can be used in computer equipment. Figure 4 It is a flowchart of another method for determining the cavitation coefficient of a mixed-flow reversible pumped-storage unit power station according to an embodiment of the present invention. As Figure 4 shown, the process includes the following steps:

[0068] Step S401, obtain the first correspondence between the initial cavitation coefficient and the specific speed of the pump-turbine in different head sections of the mixed-flow reversible pumped-storage unit power station, and adjust the first correspondence to generate a second correspondence between the power station cavitation coefficient, the safety factor, and the specific speed; the initial cavitation coefficient is the cavitation coefficient when the pump-turbine starts to cavitate; the power station cavitation coefficient is used to evaluate the cavitation performance of the pump-turbine.

[0069] Specifically, the above step S401 includes:

[0070] Step S4011: According to the first corresponding relationship, multiply the specific speed by the safety factor to obtain the second corresponding relationship among the station cavitation coefficient, the safety factor, and the specific speed.

[0071] Exemplarily, in the first corresponding relationship, multiply the specific speed by the safety factor before to obtain the second corresponding relationship between the safety factor, the specific speed, and the station cavitation coefficient.

[0072] Step S402: Generate a safety factor parameter according to the historical station cavitation coefficient parameter, the historical specific speed parameter, and the second corresponding relationship, so as to generate a third corresponding relationship between the station cavitation coefficient and the specific speed according to the safety factor parameter and the second corresponding relationship. For details, please refer to Figure 1 Step S102 of the illustrated embodiment, which will not be elaborated here.

[0073] Step S403: Obtain the first station cavitation coefficient parameter corresponding to the first head and the second station cavitation coefficient parameter corresponding to the second head according to the first specific speed parameter corresponding to the first head, the second specific speed parameter corresponding to the second head, and the third corresponding relationship; the pump lift height corresponding to the first head is greater than the pump lift height corresponding to the first head. For details, please refer to Figure 1 Step S103 of the illustrated embodiment, which will not be elaborated here.

[0074] Step S404: Generate the first suction height corresponding to the first head and the second suction height corresponding to the second head according to the first head parameter, the second head parameter, the first station cavitation coefficient parameter, and the second station cavitation coefficient parameter.

[0075] Specifically, the above step S404 includes:

[0076] Step S4041: Obtain a first product result according to the product of the first head parameter and the first station cavitation coefficient parameter; obtain the first suction height corresponding to the first head according to the difference between the first preset value and the first product result.

[0077] Step S4042: Obtain a second product result according to the product of the second head parameter and the second station cavitation coefficient parameter; obtain the second suction height corresponding to the second head according to the difference between the first preset value and the second product result.

[0078] Step S405: Adjust the first suction height to obtain a third suction height; adjust the second suction height to obtain a fourth suction height.

[0079] Specifically, the above step S405 includes:

[0080] Step S4051: Obtain the influencing factors of the suction height, and adjust the first suction height according to the influencing factors of the suction height to obtain the third suction height.

[0081] Step S4052: Adjust the second extraction height according to the influencing factors of the extraction height to obtain the fourth extraction height.

[0082] Among them, according to the influencing factors of the extraction height, the first extraction height is increased or decreased to obtain the third extraction height, and according to the influencing factors of the extraction height, the second extraction height is increased or decreased to obtain the fourth extraction height.

[0083] In some optional embodiments, according to the influencing factors of the extraction height, an influence factor is formed, and the first extraction height is adjusted according to the influence factor to obtain the third extraction height; the second extraction height is adjusted according to the influence factor to obtain the fourth extraction height.

[0084] Step S406: Obtain the first target station cavitation coefficient corresponding to the first head and the second target station cavitation coefficient corresponding to the second head according to the third extraction height, the fourth extraction height, the first head parameter, and the second head parameter.

[0085] Specifically, the above step S406 includes:

[0086] Step S4061: Obtain a first difference according to the difference between the first preset value and the first head parameter; obtain the first target station cavitation coefficient corresponding to the first head according to the quotient of the first difference and the third extraction height.

[0087] Step S4062: Obtain a second difference according to the difference between the first preset value and the second head parameter; obtain the second target station cavitation coefficient corresponding to the second head according to the quotient of the second difference and the fourth extraction height.

[0088] The method for determining the station cavitation coefficient of the mixed-flow reversible pumped-storage unit provided in this embodiment flexibly fits the complex relationship between the incipient cavitation coefficient and the specific speed through a preset power function expression, obtains a corresponding relationship that more conforms to the actual operation law of the pump-turbine, improves the accuracy of the incipient cavitation coefficient. This embodiment of the present invention considers various factors and calculates the safety factor, and the calculation result is more reliable and comprehensive. Compared with the related technology, this embodiment of the present invention determines the station cavitation coefficient through an accurate extraction height, improving the accuracy of the station cavitation coefficient.

[0089] In this embodiment, a method for determining the station cavitation coefficient based on a mixed-flow reversible pumped-storage unit is provided, which can be used in computer equipment. Figure 5 It is a flowchart of another method for determining the station cavitation coefficient based on a mixed-flow reversible pumped-storage unit according to an embodiment of the present invention. As Figure 5 shown, this process includes the following steps:

[0090] Step S501: Obtain the historical initial cavitation coefficient parameters and historical specific speed parameters of the pump-turbine in different head sections of the mixed-flow reversible pumped-storage power station.

[0091] Step S502: Analyze the historical initial cavitation coefficient parameters and historical specific speed parameters to obtain the first correspondence relationship between the specific speed and the initial cavitation coefficient.

[0092] Among them, perform power function regression statistical analysis on the historical initial cavitation coefficient parameters and historical specific speed parameters to obtain the first correspondence relationship between the specific speed and the initial cavitation coefficient.

[0093] The first correspondence relationship is:

[0094] σ i =10 -3 n q 1.413 ,

[0095] Among them, σ i is the initial cavitation coefficient, and n q is the specific speed.

[0096] Step S503: Add a safety factor to the first correspondence relationship to obtain the second correspondence relationship. Analyze the correspondence relationship between the specific speed and the safety factor based on historical data. According to the second correspondence relationship and the correspondence relationship between the specific speed and the safety factor, obtain the third correspondence relationship between the cavitation coefficient of the power station and the specific speed.

[0097] Among them, the second correspondence relationship is:

[0098] σ p =K10 -3 n q 1.413 ,

[0099] Among them, σ p is the cavitation coefficient of the power station, n q is the specific speed, and K is the safety factor.

[0100] In some optional embodiments, perform power function regression statistical analysis on the safety factor parameters and historical specific speed parameters to obtain the correspondence relationship between the safety factor and the specific speed. The correspondence relationship between the safety factor and the specific speed is:

[0101] K=3.55n q -0.29 ,

[0102] Among them, K is the safety factor, and n q is the specific speed.

[0103] In some alternative embodiments, the correspondence between the safety factor and the specific speed is combined with the second correspondence to obtain a third correspondence, which is:

[0104] σ p = 0.00355n q 1.123 ,

[0105] wherein, σ p is the cavitation coefficient of the power station, and n q is the specific speed.

[0106] Step S504: Calculate the cavitation coefficient of the power station for the specific speeds corresponding to the maximum head and the minimum head respectively, and determine the suction height according to the cavitation coefficient of the power station.

[0107] The formula for determining the suction height according to the cavitation coefficient of the power station is:

[0108] H s = 9.5 - σ p *H p ,

[0109] wherein, H s is the suction height, σ p is the cavitation coefficient parameter of the power station, and H p is the head parameter.

[0110] Step S505: Adjust the suction height according to the influencing factors of the suction height to obtain the actual suction height. Determine the cavitation coefficients of the power station corresponding to the maximum head and the minimum head respectively according to the actual suction height, and compare the cavitation coefficient of the power station with the initial cavitation coefficient to verify the cavitation coefficient of the power station.

[0111] Among them, substituting the actual suction height, the maximum head, and the minimum head into the above formula for the suction height, the cavitation coefficients of the power station corresponding to the maximum head and the minimum head are obtained, that is, the first target cavitation coefficient of the power station and the second target cavitation coefficient of the power station.

[0112] In some alternative embodiments, the cavitation coefficient of the power station is compared with the initial cavitation coefficient parameter. When the cavitation coefficient of the power station is greater than the initial cavitation coefficient parameter, a prompt message is generated. The prompt message is used to prompt that there is no need to adjust the suction height. When the cavitation coefficient of the power station is less than or equal to the initial cavitation coefficient parameter, the suction height is adjusted (it can be to increase the suction height), and the steps of returning the cavitation coefficient of the power station according to the suction height and the head parameter are performed until the cavitation coefficient of the power station is greater than the initial cavitation coefficient parameter.

[0113] In the embodiments of the present invention, Table 1 shows the comparison results of the cavitation coefficients of the power station and the actual cavitation coefficients of the power station obtained according to the embodiments of the present invention for multiple power stations.

[0114] Table 1: Comparison results of the cavitation coefficient of the power station and the actual power station cavitation coefficient.

[0115]

[0116]

[0117] As can be seen from Table 1, the deviation rate between the cavitation coefficient of the power station determined in the embodiment of the present invention and the actual power station cavitation coefficient is approximately -14.714%.

[0118] In the embodiment of the present invention, Table 2 shows the comparison results of the cavitation coefficients of the first pumped-storage power station determined by different formulas.

[0119] Table 2: Comparison results of the cavitation coefficients of the first pumped-storage power station determined by different formulas.

[0120]

[0121] In the embodiment of the present invention, Table 3 shows the comparison results of the cavitation coefficients of the second pumped-storage power station determined by different formulas.

[0122] Table 3: Comparison results of the cavitation coefficients of the second pumped-storage power station determined by different formulas.

[0123]

[0124]

[0125] In the embodiment of the present invention, Table 4 shows the comparison results of the cavitation coefficients of the third pumped-storage power station determined by different formulas.

[0126] Table 4: Comparison results of the cavitation coefficients of the third pumped-storage power station determined by different formulas.

[0127]

[0128] As can be seen from Table 2, Table 3 and Table 4, the cavitation coefficient of the power station obtained according to the cavitation coefficient formula of the embodiment of the present invention is closest to the actual value. Therefore, the accuracy of the cavitation coefficient of the power station obtained in the embodiment of the present invention is higher.

Claims

1. A method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station, characterized in that: The method comprises: Obtaining a first correspondence between the primary cavitation coefficient and the specific speed of a pump-turbine at different water head sections of a mixed flow reversible pumped storage unit power station, adjusting the first correspondence to generate a second correspondence between the power station cavitation coefficient, the safety factor and the specific speed; the primary cavitation coefficient is the cavitation coefficient when the pump-turbine begins to cavitate; the power station cavitation coefficient is used to evaluate the cavitation performance of the pump-turbine; Generate a safety factor parameter according to a historical power plant cavitation coefficient parameter, a historical specific speed parameter, and the second corresponding relationship, so as to generate a third corresponding relationship between the power plant cavitation coefficient and the specific speed according to the safety factor parameter and the second corresponding relationship; According to the first specific speed parameter corresponding to the first head, the second specific speed parameter corresponding to the second head, and the third corresponding relationship, a first power station cavitation coefficient parameter corresponding to the first head and a second power station cavitation coefficient parameter corresponding to the second head are obtained; the water pumping height corresponding to the first head is greater than the water pumping height corresponding to the first head; Generate a first suction height corresponding to the first head and a second suction height corresponding to the second head according to a first head parameter, a second head parameter, a cavitation coefficient parameter of the first power station, and a cavitation coefficient parameter of the second power station; The first suction height is adjusted to obtain a third suction height; the second suction height is adjusted to obtain a fourth suction height; According to the third suction height, the fourth suction height, the first head parameter, and the second head parameter, a first target power station cavitation coefficient corresponding to the first head and a second target power station cavitation coefficient corresponding to the second head are obtained.

2. The method according to claim 1, characterized in that The method of obtaining the first corresponding relationship between the primary cavitation coefficient and the specific speed of the pump turbine at different water head sections of the mixed flow reversible pumped storage unit power station includes: Obtaining the historical primary cavitation coefficient parameter and the historical specific speed parameter of the pump turbine at different water head sections of the mixed flow reversible pumped storage unit power station; It is preset that there exists a power function relationship between the historical initial cavitation coefficient parameter and the historical specific speed parameter, and a preset power function expression is obtained; Performing a logarithmic transformation on the preset power function expression to convert the preset power function expression into a linear model; Estimating parameters in the linear model to obtain parameter estimates; The preset power function expression is restored according to the parameter estimation value to obtain a first corresponding relationship between the primary cavitation coefficient and the specific speed.

3. The method according to claim 1 or 2, characterized in that: The adjusting the first corresponding relationship to generate a second corresponding relationship between the power plant cavitation coefficient, the safety factor and the specific speed includes: According to the first corresponding relationship, the specific speed is multiplied by the safety factor to obtain a second corresponding relationship among the power station cavitation coefficient, the safety factor and the specific speed.

4. The method according to claim 1 or 2, characterized in that: The step of generating a first suction height corresponding to the first head and a second suction height corresponding to the second head according to the first head parameter, the second head parameter, the first power station cavitation coefficient parameter, and the second power station cavitation coefficient parameter comprises: Obtain a first product result according to the product of the first head parameter and the first power station cavitation coefficient parameter; obtain the first suction height corresponding to the first head according to the difference between a first preset value and the first product result; A second product result is obtained according to the product of the second head parameter and the second power station cavitation coefficient parameter; and the second suction height corresponding to the second head is obtained according to the difference between the first preset value and the second product result.

5. The method according to claim 1 or 2, characterized in that: The first suction height is adjusted to obtain a third suction height; and the second suction height is adjusted to obtain a fourth suction height, including: Acquire a suction height influencing factor, and adjust the first suction height according to the suction height influencing factor to obtain the third suction height; The second suction height is adjusted according to the suction height influencing factor to obtain a fourth suction height.

6. The method according to claim 4, characterized in that The obtaining, according to the third suction height, the fourth suction height, the first lift parameter, and the second lift parameter, a first target power station cavitation coefficient corresponding to the first lift and a second target power station cavitation coefficient corresponding to the second lift, comprises: According to the difference between the first preset value and the first lift parameter, a first difference is obtained; according to the quotient of the first difference and the third suction height, the first target power station cavitation coefficient corresponding to the first lift is obtained; A second difference is obtained according to the difference between the first preset value and the second head parameter; and the second target power station cavitation coefficient corresponding to the second head is obtained according to the quotient of the second difference and the fourth suction height.

Images