Determination method of cavitation coefficient of mixed flow reversible pumped storage power station

Abstract

The present invention relates to the technical field of pumped storage engineering, and discloses a method for determining the cavitation coefficient of a power station based on a mixed-flow reversible pumped-storage unit. The method comprises the following steps: adjusting a first corresponding relationship between an initial cavitation coefficient and a specific speed to generate a second corresponding relationship; generating a third corresponding relationship based on a determined safety factor parameter and the second corresponding relationship; obtaining first and second power station cavitation coefficient parameters based on the first and second specific speed parameters and the third corresponding relationship; adjusting first and second suction heights generated based on first and second head parameters and the first and second power station cavitation coefficient parameters to obtain third and fourth suction heights; and obtaining first target power station cavitation coefficients and second target power station cavitation coefficients based on the third and fourth suction heights and the first and second head parameters. The present invention determines the power station cavitation coefficient by accurately determining the suction height, thereby improving the accuracy of the power station cavitation coefficient.

Description

Technical Field

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

[0002] The cavitation characteristics of a pump-turbine significantly impact its operational performance, efficiency, safety, and lifespan. They are also a key factor influencing the suction height and installation elevation of power plant units. In the early stages of pumped-storage power plant construction, the layout of the underground powerhouse hub often needs to be finalized before the pumped-storage unit manufacturer is determined. Therefore, the selection of the suction height and installation elevation of the pumped-storage unit is particularly crucial. As a key factor influencing the suction height and installation elevation, determining the cavitation characteristics of the pump-turbine is also crucial.

[0003] Currently, methods for determining the power plant cavitation coefficient of pump-turbines in pumped-storage power plants involve generating the power plant cavitation coefficient using data from existing pump-turbines with similar hydraulic heads and speeds. However, the characteristic hydraulic heads and pump-turbine specific speeds of different pumped-storage power plants vary significantly, resulting in inaccurate power plant cavitation coefficients that fail to accurately reflect the true level of cavitation performance of pump-turbines in pumped-storage power plants. Summary of the Invention

[0004] In view of this, the present invention provides a method for determining the cavitation coefficient of a power station based on a mixed flow reversible pumped storage unit to solve the problem of inaccurate power station cavitation coefficient obtained by the method for determining the power station cavitation coefficient of the pump turbine of a pumped storage power station in the relevant technology.

[0005] In the first aspect, the present invention provides a method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station, comprising: obtaining a first correspondence between the primary cavitation coefficient and the specific speed of the pump-turbine in different head sections of the mixed flow reversible pumped storage power station, adjusting the first correspondence, and generating a second correspondence between the power station cavitation coefficient, safety factor and 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; based on historical power station cavitation coefficient parameters, historical specific speed parameters and the second correspondence, a safety factor parameter is generated, so as to generate a third correspondence between the power station cavitation coefficient and the specific speed based on the safety factor parameter and the second correspondence; based on the first specific speed parameter corresponding to the first head, 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 are obtained based on the second specific speed parameter corresponding to the second head and the third corresponding relationship; the water pump lifting height corresponding to the first head is greater than the water pump lifting height corresponding to the first 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, the first suction height corresponding to the first head and the second suction height corresponding to the second head are generated; the first suction height is adjusted to obtain the third suction height; the second suction height is adjusted to obtain the fourth suction height; according to the third suction height, the fourth suction height, the first head parameter and the second head parameter, the first target power station cavitation coefficient corresponding to the first head and the second target power station cavitation coefficient corresponding to the second head are obtained.

[0006] The present invention obtains a first correspondence between the primary cavitation coefficient and the specific speed of a pump-turbine with different head sections, adjusts the first correspondence, adds a safety factor to the first correspondence, and generates a second correspondence. The present invention adjusts the first correspondence according to the safety factor, comprehensively considers parameters related to cavitation performance, and can more accurately and comprehensively determine the power plant cavitation coefficient. The present invention generates a safety factor parameter based on historical power plant cavitation coefficient parameters, historical specific speed parameters, and the second correspondence. Based on the safety factor parameter and the second correspondence, a third correspondence between the power plant cavitation coefficient and the specific speed is generated. The use of historical data makes the setting of the safety factor more scientific, and makes the correspondence between the power plant cavitation coefficient and the specific speed more reasonable. The present invention obtains the power plant cavitation coefficient parameter based on the specific speed parameters of different heads and the third correspondence, accurately obtains the corresponding power plant cavitation coefficient parameters for different heads, and provides an accurate parameter basis for power plant operation. The present invention combines the lift parameters and the power plant cavitation coefficient parameters to determine the suction heights corresponding to different lifts. Since the suction height needs to consider many factors, the suction height determined by combining the lift parameters and the power plant cavitation coefficient parameters is not accurate enough. The present invention adjusts the suction height to ensure the accuracy of the suction height. The present invention reversely infers the first target power plant cavitation coefficient and the second target power plant cavitation coefficient based on the third suction height, the fourth suction height, the first lift parameter, and the second lift parameter. Since the third suction height and the fourth suction height of the present invention are relatively accurate, the first target power plant cavitation coefficient and the second target power plant cavitation coefficient determined based on the third suction height and the fourth suction height are highly accurate and conform to the power plant cavitation coefficient under actual conditions.

[0007] In an optional embodiment, a first correspondence between the primary cavitation coefficient and the specific speed of the pump-turbine in different head sections of a mixed flow reversible pumped storage power station is obtained, including: obtaining historical primary 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; presetting a power function relationship between the historical primary cavitation coefficient parameters and the historical specific speed parameters 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 between the primary cavitation coefficient and the specific speed.

[0008] The present invention flexibly fits the complex relationship between the primary cavitation coefficient and the specific speed by presetting a power function expression, obtains a corresponding relationship that is more in line with the actual operating law of the pump turbine, and improves the accuracy of the primary cavitation coefficient.

[0009] In an optional embodiment, the first corresponding relationship is adjusted to generate a second corresponding relationship between the power plant cavitation coefficient, safety factor and specific speed, including: multiplying the specific speed by the safety factor according to the first corresponding relationship to obtain the second corresponding relationship between the power plant cavitation coefficient, safety factor and specific speed.

[0010] In an optional embodiment, a first suction height corresponding to the first head and a second suction height corresponding to the second head are generated based on the first head parameter, the second head parameter, the first power station cavitation coefficient parameter and the second power station cavitation coefficient parameter, including: obtaining a first product result based on 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 based on the difference between a first preset value and the first product result; obtaining a second product result based on the product of the second head parameter and the second power station cavitation coefficient parameter; and obtaining the second suction height corresponding to the second head based on the difference between the first preset value and the second product result.

[0011] In an optional embodiment, the first suction height is adjusted to obtain a third suction height; the second suction height is adjusted to obtain a fourth suction height, including: obtaining a suction height influencing factor, adjusting the first suction height according to the suction height influencing factor to obtain the third suction height; adjusting the second suction height according to the suction height influencing factor to obtain the fourth suction height.

[0012] In an optional embodiment, 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, including: obtaining a first difference according to the difference between the first preset value and the first head parameter; obtaining the first target power 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 power station 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 related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 It is a flow chart of a method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station according to an embodiment of the present invention.

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

[0016] Figure 3 Schematic diagram of a first correspondence relationship and a second correspondence relationship according to an embodiment of the present invention.

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

[0018] Figure 5 It is a flow chart of another method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0020] The cavitation characteristics of pump-turbines in pumped-storage power plants significantly impact their operational performance, efficiency, safety, and lifespan. They are also a key factor influencing the suction height and installation elevation of pumped-storage power station units. In the early stages of pumped-storage power station construction, the layout of the underground powerhouse hub often needs to be determined before the pumped-storage unit manufacturer is determined. Therefore, the selection of the suction height and installation elevation of the pumped-storage power station units is particularly important. As a key factor influencing the suction height and installation elevation of pumped-storage power station units, determining the cavitation characteristics of the pump-turbine is also crucial. The cavitation characteristics of the pump-turbine are typically reflected in the pump-turbine power station cavitation coefficient.

[0021] Currently, there are two common methods for determining the cavitation coefficient of a pumped-storage power station. The first method estimates the cavitation coefficient using existing pump-turbine model test data with similar heads and specific speeds. However, the characteristic heads and specific speeds of different pumped-storage power stations vary significantly, resulting in an inaccurate cavitation coefficient that fails to accurately reflect the true level of cavitation performance of the pump-turbine in the pumped-storage power station. The second method estimates the cavitation coefficient using a statistical formula. However, the current statistical formula for the cavitation coefficient of a pump-turbine power station was established a long time ago, and the calculated results do not accurately reflect the true level of 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 power station based on a mixed flow reversible pumped storage unit. The method determines the cavitation coefficient of the power station by accurately determining the suction height, thereby improving 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 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 a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

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

[0025] Step S101, obtaining a first correspondence between the primary cavitation coefficient and the specific speed of the pump-turbine at different head sections of a mixed flow reversible pumped storage unit power station, adjusting the first correspondence, and generating a second correspondence between the power station cavitation coefficient, safety factor, and specific speed; the primary 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.

[0026] Among them, the mixed flow reversible pumped storage power station is a hydropower generation facility that uses electricity during low power load to pump water to the upper reservoir, and then releases water to the lower reservoir for power generation during peak power load. The head of a pumped storage power station refers to the water level difference between the upper reservoir and the lower reservoir. The different head sections of a pumped storage power station may include a low head section, a medium head section, and a high head section. The pump turbine of the embodiment of the present invention is mainly aimed at a mixed flow reversible pump turbine. The specific speed of a pump turbine is the speed of the turbine or the pump under the optimal operating conditions of the turbine or the optimal operating conditions of the pump.

[0027] In some optional embodiments, a first correspondence between the primary cavitation coefficient and the specific speed of the pump-turbine in different head sections of the mixed flow reversible pumped storage power station is obtained, including: using a power function regression statistical analysis method to perform statistical analysis on the historical primary 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 to obtain the first correspondence between the primary cavitation coefficient and the specific speed.

[0028] Specifically, the execution process of the power function regression statistical analysis method includes: obtaining the historical primary cavitation coefficient parameters and historical specific speed parameters of the pump turbines in different head sections of the mixed flow reversible pumped storage power station; presetting a power function relationship between the historical primary cavitation coefficient parameters and the historical specific speed parameters 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 a first corresponding relationship between the primary cavitation coefficient and the specific speed.

[0029] For example, the first corresponding relationship between the primary cavitation coefficient and the specific speed is:

[0030] σ i =10 -3 n q 1.413 ,

[0031] Among them, σ i is the primary cavitation coefficient, n q is the specific speed.

[0032] In some optional embodiments, the first correspondence is adjusted to generate a second correspondence between the power plant cavitation coefficient, safety factor and specific speed, including: introducing the safety factor into the first correspondence to obtain the second correspondence between the power plant cavitation coefficient, safety factor and specific speed.

[0033] For example, the safety factor K is introduced into the first corresponding relationship, and the second corresponding relationship obtained is:

[0034] σ p =K10 -3 n q 1.413 ,

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

[0036] Step S102 : generating a safety factor parameter based on historical power plant cavitation coefficient parameters, historical specific speed parameters, and the second corresponding relationship, and generating a third corresponding relationship between power plant cavitation coefficient and specific speed based on the safety factor parameter and the second corresponding relationship.

[0037] In some optional implementations, generating a safety factor parameter based on historical power plant cavitation coefficient parameters, historical specific speed parameters, and a second corresponding relationship includes: substituting the historical power plant cavitation coefficient parameters and historical specific speed parameters into the second corresponding relationship to obtain the safety factor parameter.

[0038] In some optional embodiments, a third corresponding relationship between the power plant cavitation coefficient and the specific speed is generated based on the safety factor parameter and the second corresponding relationship, including: substituting the safety factor parameter into the second corresponding relationship to generate the third corresponding relationship between the power plant cavitation coefficient and the specific speed.

[0039] In some optional embodiments, a third correspondence between the power plant cavitation coefficient and the specific speed is generated based on the safety factor parameter and the second correspondence, and also includes: performing power function regression statistical analysis on the safety factor parameter and the historical specific speed parameter to obtain the correspondence between the safety factor and the specific speed; combining the correspondence between the safety factor and the specific speed with the second correspondence to obtain the third correspondence.

[0040] For example, Figure 2 The figure shows the relationship between the specific speed and the safety factor. The horizontal axis is the specific speed of the pump n. q The unit is m·m3 / s (meters multiplied by cubic meters per second). The vertical axis is the safety factor K. After comparing the speed and the safety factor and performing power function regression statistical analysis, the corresponding relationship between the safety factor and the specific speed is obtained as follows:

[0041] K=3.55n q -0.29 ,

[0042] Where K is the safety factor, n q is the specific speed.

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

[0044] For example, Figure 3 The figure shows the schematic diagram of the first and second corresponding relationships. The horizontal axis is the specific speed of the water pump working condition, and the vertical axis is the primary cavitation coefficient of the water pump working condition. With the different values ​​of the safety factor K, the trend line of the power station cavitation coefficient is different. The expression of the third corresponding relationship is:

[0045] σ p =0.00355n q 1.123 ,

[0046] Among them, σ p is the power station cavitation coefficient, n q is the specific speed.

[0047] Step S103, based on 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, 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; the water pump lifting height corresponding to the first head is greater than the water pump lifting height corresponding to the first head.

[0048] Among them, the head is the energy added per unit weight of water flow when the pump-turbine lifts water from a low place to a high place. It is usually expressed 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 optional embodiments, the first specific speed parameter corresponding to the first head is substituted into the third corresponding relationship to obtain the first power station cavitation coefficient parameter corresponding to the first head; the second specific speed parameter corresponding to the second head is substituted into the third corresponding relationship to obtain the second power station cavitation coefficient parameter corresponding to the second head.

[0050] Step S104 : 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.

[0051] In some optional embodiments, a first suction height corresponding to the first head and a second suction height corresponding to the second head are generated based on the first head parameter, the second head parameter, the first power station cavitation coefficient parameter, and the second power station cavitation coefficient parameter, including: obtaining a first product result based on 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 based on the difference between the first preset value and the first product result; obtaining a second product result based on the product of the second head parameter and the second power station cavitation coefficient parameter; and obtaining the second suction height corresponding to the second head based on the difference between the first preset value and the second product result.

[0052] Among them, the first preset value may 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 plant cavitation coefficient parameter, H p is the lift parameter.

[0056] Step S105 , adjusting the first suction height to obtain a third suction height; and adjusting the second suction height to obtain a fourth suction height.

[0057] In some optional embodiments, the first suction height is adjusted to obtain a third suction height; the second suction height is adjusted to obtain a fourth suction height, including: obtaining a suction height influencing factor, adjusting the first suction height according to the suction height influencing factor to obtain the third suction height; adjusting the second suction height according to the suction height influencing factor to obtain the fourth suction height.

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

[0059] In some optional embodiments, the first suction height is increased or decreased according to the suction height influencing factors to obtain a third suction height, and the second suction height is increased or decreased according to the suction height influencing factors to obtain a fourth suction height.

[0060] In some optional implementations, an influencing factor is formed according to the influencing factors of the suction height, and the first suction height is adjusted according to the influencing factor to obtain the third suction height; the second suction height is adjusted according to the influencing factor to obtain the fourth suction height.

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

[0062] Step S106 , 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.

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

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

[0065] In some optional embodiments, the method for determining the cavitation coefficient of a mixed flow reversible pumped storage unit power station further includes: comparing the first target power station cavitation coefficient with the primary cavitation coefficient parameter; when the first target power station cavitation coefficient is greater than the primary cavitation coefficient parameter, generating a first prompt message, the first prompt message being used to prompt that there is no need to adjust the third suction height; when the first target power station cavitation coefficient is less than or equal to the primary cavitation coefficient parameter, adjusting the third suction height (which may be by increasing the third suction height), returning to the step of obtaining the first target power station cavitation coefficient corresponding to the first head according to the third suction height and the first head parameter, until the third suction height is obtained. The cavitation coefficient of a target power station is greater than the primary cavitation coefficient parameter; the cavitation coefficient of a second target power station is compared with the primary cavitation coefficient parameter, and when the cavitation coefficient of the second target power station is greater than the primary cavitation coefficient parameter, a second prompt information is generated, and the second prompt information is used to prompt that there is no need to adjust the fourth suction height; when the cavitation coefficient of the second target power station is less than or equal to the primary cavitation coefficient parameter, the fourth suction height is adjusted (the fourth suction height may be increased), and the step of obtaining the second target power station cavitation coefficient corresponding to the second head according to the fourth suction height and the second head parameter is returned until the cavitation coefficient of the second target power station is greater than the primary cavitation coefficient parameter.

[0066] The present embodiment provides a method for determining the cavitation coefficient of a power station based on a mixed-flow reversible pumped-storage unit. The method obtains a first correspondence between the primary cavitation coefficient and the specific speed of a pump-turbine at different head sections, adjusts the first correspondence, and adds a safety factor to the first correspondence to generate a second correspondence. The embodiment of the present invention adjusts the first correspondence based on the safety factor, comprehensively considering parameters related to cavitation performance, and can more accurately and comprehensively determine the power station cavitation coefficient. The embodiment of the present invention generates a safety factor parameter based on historical power station cavitation coefficient parameters, historical specific speed parameters, and the second correspondence. Based on the safety factor parameter and the second correspondence, a third correspondence between the power station cavitation coefficient and the specific speed is generated. Utilizing historical data makes the setting of the safety factor more scientific and 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 based on the specific speed parameters at different heads and the third correspondence, accurately obtaining the corresponding power station cavitation coefficient parameters for different heads, and providing an accurate parameter basis for power station operation. The embodiment of the present invention combines the head parameter and the power plant cavitation coefficient parameter to determine the suction height corresponding to different heads. Since the suction height needs to consider many factors, the suction height determined by combining the head parameter and the power plant 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 reversely infers the first target power plant cavitation coefficient and the second target power plant cavitation coefficient based on 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 first target power plant cavitation coefficient and the second target power plant cavitation coefficient determined based on the third suction height and the fourth suction height are more accurate and conform to the power plant cavitation coefficient under actual conditions.

[0067] In this embodiment, a method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station is provided, which can be used in computer equipment. Figure 4 FIG. 1 is a flow chart of another method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station according to an embodiment of the present invention. Figure 4 As shown, the process includes the following steps:

[0068] Step S401, obtaining a first correspondence between the primary cavitation coefficient and the specific speed of the pump-turbine at different 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, safety factor, and specific speed; the primary 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.

[0069] Specifically, the above step S401 includes:

[0070] Step S4011: According to the first corresponding relationship, the specific speed is multiplied by the safety factor to obtain a second corresponding relationship between the power plant cavitation coefficient, the safety factor, and the specific speed.

[0071] For example, in the first corresponding relationship, the safety factor is multiplied before the specific speed to obtain the second corresponding relationship between the safety factor and the specific speed and the power plant cavitation coefficient.

[0072] Step S402: Generate a safety factor parameter based on the historical power plant cavitation coefficient parameter, the historical specific speed parameter, and the second corresponding relationship, and generate a third corresponding relationship between the power plant cavitation coefficient and the specific speed based on the safety factor parameter and the second corresponding relationship. Figure 1 Step S102 of the illustrated embodiment will not be described in detail here.

[0073] Step S403: Based on 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, 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; the water pumping height corresponding to the first head is greater than the water pumping height corresponding to the second head. Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0074] Step S404 : 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.

[0075] Specifically, the above step S404 includes:

[0076] Step S4041: obtaining a first product result based on the product of the first lift parameter and the first power station cavitation coefficient parameter; and obtaining a first suction height corresponding to the first lift based on the difference between the first preset value and the first product result.

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

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

[0079] Specifically, the above step S405 includes:

[0080] Step S4051 , obtaining an influencing factor of the suction height, and adjusting the first suction height according to the influencing factor of the suction height to obtain a third suction height.

[0081] Step S4052: adjusting the second suction height according to the suction height influencing factors to obtain a fourth suction height.

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

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

[0084] Step S406 , 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.

[0085] Specifically, the above step S406 includes:

[0086] Step S4061: obtaining a first difference value based on the difference between the first preset value and the first lift parameter; and obtaining a first target power station cavitation coefficient corresponding to the first lift based on the quotient of the first difference value and the third suction height.

[0087] Step S4062: Obtain a second difference value based on the difference between the first preset value and the second lift parameter; and obtain a second target power station cavitation coefficient corresponding to the second lift based on the quotient of the second difference value and the fourth suction height.

[0088] The method for determining the cavitation coefficient of a mixed flow reversible pumped storage unit power station provided in this embodiment flexibly fits the complex relationship between the primary cavitation coefficient and the specific speed through a preset power function expression, thereby obtaining a corresponding relationship that is more in line with the actual operating rules of the pump turbine, thereby improving the accuracy of the primary cavitation coefficient. The embodiment of the present invention takes into account multiple factors and calculates the safety factor, and the calculation results are more reliable and comprehensive. Compared with the relevant technology, the embodiment of the present invention determines the power station cavitation coefficient through accurate suction height, thereby improving the accuracy of the power station cavitation coefficient.

[0089] In this embodiment, a method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station is provided, which can be used in computer equipment. Figure 5 FIG. 1 is a flow chart of another method for determining the cavitation coefficient of a mixed flow reversible pumped storage power station according to an embodiment of the present invention. Figure 5 As shown, the process includes the following steps:

[0090] Step S501 : obtaining historical incipient cavitation coefficient parameters and historical specific speed parameters of pump turbines at different head sections of a mixed flow reversible pumped storage power station.

[0091] Step S502 : Analyze historical incipient cavitation coefficient parameters and historical specific speed parameters to obtain a first corresponding relationship between specific speed and incipient cavitation coefficient.

[0092] Among them, the power function regression statistical analysis of the historical incipient cavitation coefficient parameters and the historical specific speed parameters was performed to obtain the first corresponding relationship between the specific speed and the incipient cavitation coefficient.

[0093] The first correspondence is:

[0094] σ i =10 -3 n q 1.413 ,

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

[0096] In step S503, a safety factor is added to the first corresponding relationship to obtain a second corresponding relationship. The corresponding relationship between the specific speed and the safety factor is analyzed based on historical data. Based on the second corresponding relationship and the corresponding relationship between the specific speed and the safety factor, a third corresponding relationship between the power plant cavitation coefficient and the specific speed is obtained.

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

[0098] σ p =K10 -3 n q 1.413 ,

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

[0100] In some optional implementations, a power function regression statistical analysis is performed on the safety factor parameter and the historical specific speed parameter to obtain a corresponding relationship between the safety factor and the specific speed. The corresponding relationship between the safety factor and the specific speed is:

[0101] K=3.55n q -0.29 ,

[0102] Where K is the safety factor, n q is the specific speed.

[0103] In some optional implementations, 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] Among them, σ p is the power station cavitation coefficient, n q is the specific speed.

[0106] Step S504 , calculating the power plant cavitation coefficient using the specific speeds corresponding to the maximum head and the minimum head, and determining the suction height according to the power plant cavitation coefficient.

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

[0108] H s =9.5-σ p *H p ,

[0109] Among them, H s is the suction height, σ p is the power plant cavitation coefficient parameter, H p is the lift parameter.

[0110] Step S505: Adjust the suction height according to the factors affecting the suction height to obtain the actual suction height, determine the power plant cavitation coefficients corresponding to the maximum head and the minimum head according to the actual suction height, and compare the power plant cavitation coefficient with the primary cavitation coefficient to verify the power plant cavitation coefficient.

[0111] The actual suction height, maximum head and minimum head are substituted into the above suction height formula to obtain the power station cavitation coefficients corresponding to the maximum head and minimum head, respectively, i.e. the first target power station cavitation coefficient and the second target power station cavitation coefficient.

[0112] In some optional embodiments, the power plant cavitation coefficient is compared with the primary cavitation coefficient parameter. When the power plant cavitation coefficient is greater than the primary cavitation coefficient parameter, a prompt message is generated. The prompt message is used to indicate that there is no need to adjust the suction height. When the power plant cavitation coefficient is less than or equal to the primary cavitation coefficient parameter, the suction height is adjusted (the suction height can be increased), and the step of calculating the power plant cavitation coefficient according to the suction height and head parameters is returned until the power plant cavitation coefficient is greater than the primary cavitation coefficient parameter.

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

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

[0115]

[0116]

[0117] As can be seen from Table 1, the deviation rate between the power plant cavitation coefficient determined by the embodiment of the present invention and the actual power plant 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 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 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 of the cavitation coefficients of the third pumped storage power station determined by different formulas.

[0127]

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

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 an incipient cavitation coefficient and a specific speed of a pump-turbine at different head sections of a mixed flow reversible pumped storage power station, adjusting the first correspondence to generate a second correspondence between a power station cavitation coefficient, a safety factor, and the specific speed; the incipient cavitation coefficient is the cavitation coefficient at which 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 a historical power plant cavitation coefficient parameter, a historical specific speed parameter, and the second corresponding relationship, and generating 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; 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 according to a first specific speed parameter corresponding to the first head, a second specific speed parameter corresponding to the second head, and the third corresponding relationship; the water pumping height corresponding to the first head is greater than the water pumping 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; The first suction height is adjusted to obtain a third suction height; the second suction height is adjusted to obtain a fourth suction height; 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 according to the third suction height, the fourth suction height, the first head parameter, and the second head parameter.

2. The method according to claim 1, characterized in that The method of obtaining a first corresponding relationship between the primary cavitation coefficient and the specific speed of the pump-turbine at different head sections of the mixed flow reversible pumped storage power station includes: Obtaining historical primary cavitation coefficient parameters and historical specific speed parameters of the pump-turbine at different head sections of a mixed flow reversible pumped storage power station; There is a preset power function relationship between the historical incipient 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 incipient 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 plant cavitation coefficient, the safety factor, and the specific speed.

4. The method according to claim 1 or 2, characterized in that 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 includes: Obtaining a first product result based on the product of the first lift parameter and the first power station cavitation coefficient parameter; obtaining the first suction height corresponding to the first lift based on a 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 adjusting the first suction height to obtain a third suction height; and adjusting the second suction height to obtain a fourth suction height, include: Obtaining an influencing factor of the suction height, and adjusting the first suction height according to the influencing factor of the suction height to obtain the third suction height; The second suction height is adjusted according to the suction height influencing factors to obtain a fourth suction height.

6. The method according to claim 4, characterized in that 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 includes: Obtaining a first difference value based on a difference between the first preset value and the first lift parameter; and obtaining the first target power station cavitation coefficient corresponding to the first lift based on a quotient of the first difference value and the third suction height. 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.

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