Coupling modeling method of leakage ball valve in pumped storage power station based on circuit equivalent theory

Abstract

This invention discloses a coupled modeling method for leakage ball valves in pumped-storage power stations based on circuit equivalence theory. The method equates the working sealing leakage path of the ball valve to an RL circuit including flow path and flow resistance, deriving the differential equations for leakage flow rate and pressure difference. A dynamic model of the moving ring is established, obtaining the relationship between the moving ring displacement and the head difference. Based on the geometric relationship between the moving ring and the valve core gap, a dynamic relationship between leakage flow rate and head difference is constructed, using characteristic parameters to characterize the hysteresis effect of output chamber water pressure changes. A pipeline water hammer wave propagation model is established using the method of characteristics, with the leakage flow rate as the downstream boundary condition for coupled solution. A genetic algorithm is used to optimize the characteristic parameters using the integral of the time-domain absolute error of the simulated and measured pressure envelopes as the fitness function. This method overcomes the shortcomings of existing empirical formulas in characterizing the influence of sealing structure parameters, achieving quantitative characterization of the degree of seal deterioration, and can be integrated into power station monitoring systems for seal failure early warning.

Description

Technical Field

[0001] This invention belongs to the field of hydropower system modeling technology, and in particular relates to a coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory. Background Technology

[0002] With the large-scale grid connection of intermittent new energy sources such as wind and solar power, the frequency stability and power supply reliability of the power grid face severe challenges. Pumped storage power stations, with their core regulation functions such as peak shaving and valley filling, frequency regulation and phase regulation, and emergency backup, have become a mature and reliable regulation resource in the current power grid. In the complex hydraulic mechanical system of a pumped storage power station, the inlet ball valve is a key device located between the turbine casing and the pressure pipeline, undertaking multiple functions: coordinating and controlling water flow during normal start-up and shutdown of the unit, reducing unit leakage during shutdown, quickly cutting off water flow to prevent the escalation of the accident during unit maintenance or emergency conditions, and reducing water hammer pressure during transition. However, under long-term high head and high start-up and shutdown frequency operating environments, the working sealing components of the ball valve are prone to sealing deterioration and leakage failure due to the aging of the sealing ring. This sealing failure will trigger a series of chain reactions: leakage causes the ball valve to change from a rigid shut-off state to flexible valve characteristics; under the disturbance of the water intake system, the working seal enters an oscillating state, inducing periodic pressure fluctuations in the pipeline water; when the leakage flow and pressure pulsation form a positive feedback, it will generate strong self-excited vibration. Analyzing the formation mechanism of this self-excited vibration and assessing its hazards requires establishing a model that accurately characterizes the dynamic relationship between leakage flow and head difference, and coupling this dynamic relationship with the water hammer wave propagation process of the water diversion system. Therefore, how to perform refined coupled modeling of the leakage ball valve of the pumped storage power station is a technical problem that urgently needs to be solved in this field.

[0003] To address the aforementioned technical problems, existing technologies typically address these issues from three levels. The first level is empirical estimation of leakage. In engineering practice, ball valve leakage is often approximated as orifice outflow or gap flow. Simplified empirical formulas are used to establish a static correlation between leakage flow and head difference, thereby using the leakage flow rate to assess the sealing condition or estimate water loss during shutdown. These empirical formulas are simple and easy to apply in engineering, and are currently the primary means of evaluating ball valve leakage during power plant design. However, the empirical coefficients in these formulas usually depend on experimental calibration of specific ball valves, making them difficult to directly apply under different sealing gaps and degrees of seal deterioration. The second level is improved design of the sealing structure. To delay the aging and wear of sealing components, existing technologies optimize the material and structural configuration of the sealing ring, and introduce elastic compensation mechanisms and adaptive pre-tightening mechanisms to maintain the contact pressure of the sealing surface, thereby reducing leakage. Some solutions also improve the reliability of the working seal by increasing the operating oil pressure level and improving the sealing ring's actuation mechanism, extending the seal life from a mechanical structural perspective. The third level is numerical simulation analysis. In terms of sealing performance evaluation, the finite element method is used to calculate the distribution of contact stress and sealing specific pressure on the sealing surface, verify whether the sealing structure meets the requirements of the required specific pressure and allowable specific pressure under different internal pressure conditions, and determine the rationality of the ball valve sealing design. In terms of water intake system response evaluation, the characteristic line method is used to numerically solve the hydraulic transition process of the pressure pipeline. The pipeline is discretized into calculation units and combined with upstream and downstream boundary conditions to simulate the pressure fluctuation and attenuation characteristics of the water intake system during dynamic processes such as unit start-up and shutdown and load shedding, thereby verifying the water hammer safety of pipelines and equipment such as ball valves. In addition, some studies combine measured leakage data from test benches with empirical coefficients or use measured pressure envelopes to verify the simulation results of the transition process. However, overall, the above methods serve three relatively independent purposes: sealing structure verification, leakage flow estimation, and hydraulic response evaluation, and lack a unified dynamic model to connect them.

[0004] However, the aforementioned existing technologies have significant shortcomings and are insufficient to meet the requirements of coupled modeling of leaking ball valves. When relying on empirical formulas to estimate leakage flow, these formulas only provide a static average leakage estimate and cannot reflect the impact of changes in sealing structure parameters on the dynamic characteristics of leakage. The dynamic evolution of leakage flow during seal deterioration is completely ignored. Chinese patent CN105221782A discloses a finite element analysis modeling method for the sealing performance of large-diameter fully welded ball valves. However, this method calculates the average sealing specific pressure using theoretical formulas and analyzes the stress distribution on the sealing surface using finite element analysis, focusing on the static verification of the sealing structure. It does not establish a dynamic relationship between leakage flow and head difference, and cannot characterize the dynamic changes in leakage characteristics during seal deterioration. When using the method of characteristics to calculate the transient process of the water intake system, traditional methods simplify the valve process to a fixed boundary or known flow process, decoupling the dynamic model of leakage flow from the propagation of water hammer waves in the pipeline. Chinese patent CN106013319A discloses a method for calculating the ultimate runaway water hammer pressure in a water supply system. However, this method uses the pump operating characteristics to couple the water hammer propagation to solve for pipeline pressure, without considering the flexible valve boundary characteristics caused by ball valve leakage, and thus cannot reflect the feedback effect of leakage flow on pressure fluctuations. Solutions that improve sealing performance from a mechanical structure perspective also fail to solve the aforementioned dynamic coupling problem. Chinese patent CN103363145A discloses a high-oil-pressure operation hard-seal structure for a hydropower station inlet ball valve. However, this method improves sealing reliability through sealing ring compression compensation and sand-blocking structures, but fails to establish a dynamic model of the moving parts from the perspective of water pressure hysteresis. Therefore, it cannot characterize the positive feedback mechanism of the output chamber water pressure hysteresis driving the increase in leakage flow, thereby inducing self-excited vibration of the water intake system. Thus, a coupling modeling method for leaking ball valves in pumped-storage power stations based on circuit equivalence theory is needed to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a coupled modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory. It aims to overcome the shortcomings of existing ball valve leakage modeling, which relies on empirical formulas, decouples leakage dynamics and water hammer propagation, and cannot quantify the degree of seal deterioration. It has the characteristics of uniformly characterizing the leakage path hysteresis response, active loop dynamics and water hammer wave propagation with circuit equivalence theory and realizing automatic parameter identification and optimization.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A coupled modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory includes the following steps: Step 1: Based on the circuit equivalence theory, establish a fluid dynamic model of the ball valve's working seal leakage path, and equate the leakage path to include the flow path. and flow resistance RL circuit, influenza Hysteresis effect characterizing changes in water pressure in the output chamber, flow resistance Characterizes the viscous resistance of fluids; Step 2: Establish the dynamic model of the moving ring and obtain the displacement of the moving ring. head difference Relationship; Step 3, construct valve leakage flow rate head difference The dynamic relationship, let the characteristic parameters ,in For the high-voltage side volume; Step 4: Establish a pipeline water hammer wave propagation model using the method of characteristics; Step 5: Construct a fitness function using the time-domain absolute error integral of the simulated and measured pressure envelopes via a genetic algorithm, and optimize the feature parameters. Optimal output value.

[0007] Preferably, in step 1, the RL circuit satisfies the leakage flow rate requirement. With pressure difference Differential equation: ; in, This refers to the pressure difference between the input and output chambers of the ball valve. For leaked flow, It's the flu. For flow resistance, For time.

[0008] Preferably, the influenza and flow resistance The influenza virus is determined based on the equivalent geometric dimensions of the leakage path and fluid property parameters. satisfy: ; The flow resistance satisfy: ; in, The equivalent length of the leakage path. The equivalent cross-sectional area of ​​the leakage path. The sealing contact width of the movable ring, The height of the sealing gap. This refers to the fluid dynamic viscosity.

[0009] Preferably, in step 2, the pressure difference head difference The conversion relationship is as follows: ; in, For fluid density, It is the acceleration due to gravity. This is due to head difference.

[0010] Preferably, in step 2, establishing the dynamic model of the moving ring includes establishing the resultant force acting on the moving ring. head difference Relationship: ; in, The net force on the moving ring, The water pressure in the input chamber, The water pressure in the output chamber. The effective pressure area of ​​the output chamber water pressure on the moving ring. The effective pressure area of ​​the input chamber water pressure on the moving ring. Let the pressure area of ​​the water pressure inside the valve cavity on the moving ring be such that it satisfies the following conditions: .

[0011] Preferably, in step 2, the displacement of the movable ring is obtained. head difference The relationship includes: ignoring the flow resistance Influenced by Newton's second law, the acceleration of the moving ring is integraled twice over time and simplified using fluid-structure interaction to obtain the following relationship: ; in, For the quality of the active ring, The bulk elastic modulus of water. For high-voltage side volume and satisfy ,in This is the activity loop.

[0012] Preferably, in step 3, the valve leakage flow rate head difference The dynamic relationship is as follows: ; in, For leaked flow, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. For fluid density, The bulk elastic modulus of water. For the quality of the active ring, Due to head difference, For influenza; characteristic parameters , The larger the value, the stronger the lag in the change of water pressure in the output chamber.

[0013] Preferably, the derivation process of the dynamic relationship uses the gap between the moving ring and the valve core. The gap Displacement of the moving ring satisfy: ; Valve leakage flow Through the gap Represented as: ; in, The gap between the moving ring and the valve core. For the displacement of the moving ring, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For valve diameter, It is the acceleration due to gravity. This is due to head difference.

[0014] Preferably, the dynamic relation is expressed as: ; Among them, the intermediate coefficient , satisfy: ; ; in, , As an intermediate coefficient, With characteristic parameters It increases linearly.

[0015] Furthermore, by substituting the actual ball valve data, we obtain... , ,in These are characteristic parameters.

[0016] Preferably, in step 4, establishing the pipeline water hammer wave propagation model using the method of characteristics includes: discretizing the pipeline into... Each computational unit takes a time step. ,in For spatial step size, Let be the water hammer wave velocity; the governing equation for the water hammer wave is: ; ; in, For the water head, The flow rate in the pipeline is equivalent to the leakage flow rate at the ball valve end. These are the position coordinates along the pipeline axis. For time, The cross-sectional area of ​​the pipe. For pipe diameter, This is the coefficient of friction.

[0017] Preferably, along the positive feature line The direction and the equation of the characteristic line are: ; Along the reverse feature line The direction and the equation of the characteristic line are: ; ; ; in, The number of computational units is [number]; the upstream boundary conditions are [conditions]. ,in For the head of the first node of the pipeline, The upstream reservoir head is given; the downstream boundary conditions are: ; in, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For fluid density, It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. The bulk elastic modulus of water. For the quality of the active ring, It's influenza.

[0018] Preferably, in step 5, the feature parameters are optimized using a genetic algorithm. This includes: setting the population size and crossover probability. and mutation probability Initialize the population and calculate individual fitness; generate offspring through selection, arithmetic crossover, and Gaussian mutation; merge the parent and offspring populations using an elitist retention strategy; set convergence criteria, iterate until convergence, and output the optimal value. value.

[0019] Furthermore, the crossover probability Probability of mutation The population size is 50.

[0020] Preferably, the selection adopts a roulette wheel selection method, and the convergence condition is: when consecutive The change in the fitness of the optimal individual over generations is less than the convergence threshold. Or the number of iterations reaches the maximum number of iterations. When the genetic algorithm has converged, the iteration is terminated; wherein the convergence threshold is... Take the initial population with the optimal fitness times, , .

[0021] Preferably, a coupled modeling system for a leaking ball valve in a pumped-storage power station based on circuit equivalence theory is used to execute the coupled modeling method for the leaking ball valve in a pumped-storage power station based on circuit equivalence theory. The system includes a leakage path equivalent modeling module, a moving-loop dynamics modeling module, a leakage dynamic relationship construction module, a water hammer wave propagation solution module, and a parameter optimization module. The leakage path equivalent modeling module is used to equate the working sealing leakage path of the ball valve to include a flow path. and flow resistance The RL circuit outputs leakage flow. With pressure difference Differential equations; The active ring dynamics modeling module is used to model based on pressure difference. The corresponding head difference establishes the active loop displacement. head difference The relationship is given, and the displacement of the active loop is output. ; The leakage dynamic relationship construction module is used to construct the dynamic relationship based on the displacement of the active ring. Build Leakage Flow head difference The dynamic relationship is used to determine the characteristic parameters. And output the dynamic relation, where For the high-voltage side volume; The water hammer wave propagation solver module is used to output leakage flow rate as a dynamic formula. As downstream boundary conditions, the characteristic line method is used to solve the pipeline water hammer wave propagation model, output the water head of each node in the pipeline and form the simulated pressure envelope. The parameter optimization module uses a genetic algorithm to optimize feature parameters, with the integral of the time-domain absolute error between the simulated and measured pressure envelopes as the fitness function. Optimal output Value and will be optimal The value is fed back to the leakage dynamic relation building module to update the dynamic relation.

[0022] Preferably, a computer device includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory.

[0023] Preferably, a computer-readable storage medium stores computer instructions, which are used to cause a computer to execute the described coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory.

[0024] The beneficial effects of this invention are as follows: 1. This invention equates the leakage path of a ball valve working seal to an RL circuit including flow path and flow resistance, derives the differential equation satisfied by the leakage flow rate and pressure difference, and establishes a dynamic model of the moving ring and the relationship between the moving ring displacement and head difference based on this. Furthermore, it constructs a dynamic relationship between the leakage flow rate and head difference, achieving a joint characterization of water pressure hysteresis, viscous resistance, and the inertial response of the moving ring during ball valve leakage. This solves the shortcomings of existing technologies that only estimate the static average leakage flow rate using empirical formulas and cannot characterize the influence of sealing structure parameters on the dynamic characteristics of leakage. In this scheme, flow path represents the hysteresis effect of water pressure change in the output chamber, and flow resistance represents the fluid viscous resistance, allowing the dynamic response of the leakage path to be explicitly expressed; by setting characteristic parameters... The product of the influenza virus volume and the high-pressure side volume. The magnitude of the value directly reflects the strength of the water pressure hysteresis effect in the output chamber, providing a clear theoretical basis for the quantitative characterization of the degree of deterioration of the ball valve seal.

[0025] 2. This invention establishes the geometric relationship between the gap between the moving ring and the valve core and the displacement of the moving ring, and derives the expression for the leakage flow rate based on this gap. This leakage flow rate is used as the downstream boundary condition of the water hammer wave propagation model. The pipeline is discretized into computational units using the method of characteristics, and iteratively solved using a discrete format where the ratio of the time step to the spatial step is equal to the reciprocal of the water hammer wave velocity. This achieves the coupled solution of the dynamic model of the ball valve leakage flow rate and the water hammer wave propagation in the water intake system, overcoming the shortcomings of existing technologies that decouple the leakage link from water hammer propagation and cannot assess the feedback effect of leakage flow rate on pressure pulsation. When the water intake system is disturbed, this scheme can synchronously and iteratively calculate the head and flow rate at each node of the pipeline, ensuring a consistent expression of the change in leakage flow rate over time and its feedback to pipeline pressure fluctuations. It can reproduce the process of leakage flow rate and pressure pulsation mutually reinforcing each other to form a positive feedback, providing a refined numerical means for assessing the pressure fluctuation amplitude and self-excited vibration risk of the water intake system under working sealing oscillation conditions.

[0026] 3. This invention utilizes a genetic algorithm with the time-domain absolute error integral between the simulated and measured pressure envelopes as the fitness function. It incorporates genetic operations such as selection, arithmetic crossover, and Gaussian mutation, and employs an elite retention strategy to automatically search for optimized feature parameters that allow the simulation results to approximate the measured results. This approach overcomes the shortcomings of existing technologies that rely on manual trial-and-error to tune model parameters and struggle to adapt to dynamic changes in sealed conditions. The genetic algorithm uses population size, crossover probability, and mutation probability as configurable parameters, and employs a convergence criterion based on the optimal individual fitness change and the maximum number of iterations. This ensures the stability and repeatability of the parameter identification process, allowing the model to continuously calibrate as running data accumulates. The optimized feature parameters... This parameter quantitatively reflects the hysteresis of the output chamber water pressure under the current sealed state. After integrating the inversion results into the power plant monitoring system, the genetic algorithm can be repeatedly executed to optimize and update the characteristic parameters as the system operates. The value of the characteristic parameter is continuously monitored. The changing trend provides a basis for early warning of sealing failure and maintenance decisions, thereby avoiding the occurrence of self-excited vibration accidents in the water diversion system induced by the deterioration of ball valve seals. Attached Figure Description

[0027] Figure 1 This is a research framework diagram in an embodiment of the present invention; Figure 2 This is a schematic diagram of the water diversion system topology in an embodiment of the present invention; Figure 3 This is a three-dimensional structural diagram of the ball valve in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the evolution of the working sealing state in an embodiment of the present invention; Figure 5 This is a schematic diagram of the leakage area-displacement relationship of the flexible valve in an embodiment of the present invention; Figure 6 This is an equivalent schematic diagram of the fluid leakage path circuit in an embodiment of the present invention; Figure 7 This is a schematic diagram of the feature line method computation network in an embodiment of the present invention; Figure 8 This is a schematic diagram of the genetic algorithm optimization process in an embodiment of the present invention; Figure 9 This is a convergence curve of the fitness function in an embodiment of the present invention. Detailed Implementation

[0028] Example 1: A coupled modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory includes the following steps: Step 1: Based on the circuit equivalence theory, establish a fluid dynamic model of the ball valve's working seal leakage path, and equate the leakage path to include the flow path. and flow resistance RL circuit, influenza Hysteresis effect characterizing changes in water pressure in the output chamber, flow resistance Characterizes the viscous resistance of fluids; Step 2: Establish the dynamic model of the moving ring and obtain the displacement of the moving ring. head difference Relationship; Step 3, construct valve leakage flow rate head difference The dynamic relationship, let the characteristic parameters ,in For the high-voltage side volume; Step 4: Establish a pipeline water hammer wave propagation model using the method of characteristics; Step 5: Construct a fitness function using the time-domain absolute error integral of the simulated and measured pressure envelopes via a genetic algorithm, and optimize the feature parameters. Optimal output value.

[0029] Preferably, in step 1, the RL circuit satisfies the leakage flow rate requirement. With pressure difference Differential equation: ; in, This refers to the pressure difference between the input and output chambers of the ball valve. For leaked flow, It's the flu. For flow resistance, For time.

[0030] Preferably, the influenza and flow resistance The influenza virus is determined based on the equivalent geometric dimensions of the leakage path and fluid property parameters. satisfy: ; The flow resistance satisfy: ; in, The equivalent length of the leakage path. The equivalent cross-sectional area of ​​the leakage path. The sealing contact width of the movable ring, The height of the sealing gap. This refers to the fluid dynamic viscosity.

[0031] Preferably, in step 2, the pressure difference head difference The conversion relationship is as follows: ; in, For fluid density, It is the acceleration due to gravity. This is due to head difference.

[0032] Preferably, in step 2, establishing the dynamic model of the moving ring includes establishing the resultant force acting on the moving ring. head difference Relationship: ; in, The net force on the moving ring, The water pressure in the input chamber, The water pressure in the output chamber. The effective pressure area of ​​the output chamber water pressure on the moving ring. The effective pressure area of ​​the input chamber water pressure on the moving ring. Let the pressure area of ​​the water pressure inside the valve cavity on the moving ring be such that it satisfies the following conditions: .

[0033] Preferably, in step 2, the displacement of the movable ring is obtained. head difference The relationship includes: ignoring the flow resistance Influenced by Newton's second law, the acceleration of the moving ring is integraled twice over time and simplified using fluid-structure interaction to obtain the following relationship: ; in, For the quality of the active ring, The bulk elastic modulus of water. For high-voltage side volume and satisfy ,in This is the activity loop.

[0034] Preferably, in step 3, the valve leakage flow rate head difference The dynamic relationship is as follows: ; in, For leaked flow, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. For fluid density, The bulk elastic modulus of water. For the quality of the active ring, Due to head difference, For influenza; characteristic parameters , The larger the value, the stronger the lag in the change of water pressure in the output chamber.

[0035] Preferably, the derivation process of the dynamic relationship uses the gap between the moving ring and the valve core. The gap Displacement of the moving ring satisfy: ; Valve leakage flow Through the gap Represented as: ; in, The gap between the moving ring and the valve core. For the displacement of the moving ring, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For valve diameter, It is the acceleration due to gravity. This is due to head difference.

[0036] Preferably, the dynamic relation is expressed as: ; Among them, the intermediate coefficient , satisfy: ; ; in, , As an intermediate coefficient, With characteristic parameters It increases linearly.

[0037] Furthermore, by substituting the actual ball valve data, we obtain... , ,in These are characteristic parameters.

[0038] Preferably, in step 4, establishing the pipeline water hammer wave propagation model using the method of characteristics includes: discretizing the pipeline into... Each computational unit takes a time step. ,in For spatial step size, Let be the water hammer wave velocity; the governing equation for the water hammer wave is: ; ; in, For the water head, The flow rate in the pipeline is equivalent to the leakage flow rate at the ball valve end. These are the position coordinates along the pipeline axis. For time, The cross-sectional area of ​​the pipe. For pipe diameter, This is the coefficient of friction.

[0039] Preferably, along the positive feature line The direction and the equation of the characteristic line are: ; Along the reverse feature line The direction and the equation of the characteristic line are: ; ; ; in, The number of computational units is [number]; the upstream boundary conditions are [conditions]. ,in For the head of the first node of the pipeline, The upstream reservoir head is given; the downstream boundary conditions are: ; in, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For fluid density, It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. The bulk elastic modulus of water. For the quality of the active ring, It's influenza.

[0040] Preferably, in step 5, the feature parameters are optimized using a genetic algorithm. This includes: setting the population size and crossover probability. and mutation probability Initialize the population and calculate individual fitness; generate offspring through selection, arithmetic crossover, and Gaussian mutation; merge the parent and offspring populations using an elitist retention strategy; set convergence criteria, iterate until convergence, and output the optimal value. value.

[0041] Furthermore, the crossover probability Probability of mutation The population size is 50.

[0042] Preferably, the selection adopts a roulette wheel selection method, and the convergence condition is: when consecutive The change in the fitness of the optimal individual over generations is less than the convergence threshold. Or the number of iterations reaches the maximum number of iterations. When the genetic algorithm has converged, the iteration is terminated; wherein the convergence threshold is... Take the initial population with the optimal fitness times, , .

[0043] Preferably, a coupled modeling system for a leaking ball valve in a pumped-storage power station based on circuit equivalence theory is used to execute the coupled modeling method for the leaking ball valve in a pumped-storage power station based on circuit equivalence theory. The system includes a leakage path equivalent modeling module, a moving-loop dynamics modeling module, a leakage dynamic relationship construction module, a water hammer wave propagation solution module, and a parameter optimization module. The leakage path equivalent modeling module is used to equate the working sealing leakage path of the ball valve to include a flow path. and flow resistance The RL circuit outputs leakage flow. With pressure difference Differential equations; The active ring dynamics modeling module is used to model based on pressure difference. The corresponding head difference establishes the active loop displacement. head difference The relationship is given, and the displacement of the active loop is output. ; The leakage dynamic relationship construction module is used to construct the dynamic relationship based on the displacement of the active ring. Build Leakage Flow head difference The dynamic relationship is used to determine the characteristic parameters. And output the dynamic relation, where For the high-voltage side volume; The water hammer wave propagation solver module is used to output leakage flow rate as a dynamic formula. As downstream boundary conditions, the characteristic line method is used to solve the pipeline water hammer wave propagation model, output the water head of each node in the pipeline and form the simulated pressure envelope. The parameter optimization module uses a genetic algorithm to optimize feature parameters, with the integral of the time-domain absolute error between the simulated and measured pressure envelopes as the fitness function. Optimal output Value and will be optimal The value is fed back to the leakage dynamic relation building module to update the dynamic relation.

[0044] Preferably, a computer device includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory.

[0045] Preferably, a computer-readable storage medium stores computer instructions, which are used to cause a computer to execute the described coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory.

[0046] Example 2: This embodiment takes a ball valve leakage self-excited vibration accident that actually occurred in a pumped storage power station as the research object, and describes in detail the specific implementation process of the present invention; its implementation process is as follows: Figure 1 As shown, it includes the following steps: The first step is to define the system topology and boundaries, and the water diversion system structure is as follows: Figure 2 As shown.

[0047] Pipeline parameters are shown in Table 1: Table 1: Pipeline parameters;

[0048] Step 2: Modeling the sealing characteristics of the ball valve: The three-dimensional structure and working sealing components of the ball valve in this power station are as follows: Figure 3 As shown, Figure 4 The demonstrations presented four operating conditions: (a) an intact rubber seal, (b) a partially damaged rubber seal, (c) a deformed and stuck rubber seal, and (d) a rubber seal that had been washed away. Based on... Figure 4 In the poor sealing condition in (b), the pressure response of the output chamber is lag-induced, resulting in a positive feedback of pressure increase.

[0049] based on Figure 5 Establish the formula for the valve flow rate in relation to the clearance between the valve's moving ring and valve core: ; The third step is to collect the raw information of each indicator in the indicator layer: Constructing the RL equivalent circuit as follows Figure 6 As shown. Influenza L Hysteresis effect characterizing changes in water pressure in the output chamber, flow resistanceR The leakage flow rate characterizes the viscous resistance of the fluid. Q With pressure difference ΔP Satisfy the differential equation, i.e. .

[0050] Step 4: Dynamic modeling of the active ring: Establish the combined pressure of the activity loop F head difference H The relationship, that is .

[0051] In the above formula, P 1 represents the water pressure in the input chamber; P 2 represents the water pressure in the output chamber; P 3 represents the water pressure inside the valve body. S 1 represents the effective pressure area of ​​the water pressure in the input cavity on the moving ring; S 2 represents the effective pressure area of ​​the water pressure in the output chamber on the moving ring; S 3 represents the pressure area of ​​the moving ring caused by the water pressure inside the valve cavity, and satisfies... S 1= S 2 +S 3.

[0052] After simplifying the problem, we can derive the expression for displacement s using Newton's second law: ; In the above formula , l It is the range of left and right displacement that the movable ring can move.

[0053] Step 5: Standardization of quantitative indicator data: Combining the above two equations, we obtain the core formula: ; ; k=LV ; ; Substituting the actual data of a certain ball valve yields k 1 = 0.1574861790 k 2 = 7.160137659 × 10 -10 ·k ; k The larger the value, the stronger the lag in the change of water pressure in the output chamber.

[0054] Step 6: Solve using the water hammer characteristic line method: based on Figure 7 Discretize the pipeline, time step Δt=Δx / a Upstream boundary conditions: Downstream boundary conditions: .

[0055] Step 7, as Figure 8 and Figure 9 As shown, the genetic algorithm parameters are optimized as follows: Fitness function: the integral of the absolute error between the simulated and measured pressure envelopes; Parameter settings: pc=0.8, pm=0.1, population size 50; Output optimal value k= 151153.8611.

Claims

1. A coupled modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory, characterized in that, Includes the following steps: Step 1: Based on the circuit equivalence theory, establish a fluid dynamic model of the ball valve's working seal leakage path, and equate the leakage path to include the flow path. and flow resistance RL circuit, influenza Hysteresis effect characterizing changes in water pressure in the output chamber, flow resistance Characterizes the viscous resistance of fluids; Step 2: Establish the dynamic model of the moving ring and obtain the displacement of the moving ring. head difference Relationship; Step 3, construct valve leakage flow rate head difference The dynamic relationship, let the characteristic parameters ,in For the high-voltage side volume; Step 4: Establish a pipeline water hammer wave propagation model using the method of characteristics; Step 5: Construct a fitness function using the time-domain absolute error integral of the simulated and measured pressure envelopes via a genetic algorithm, and optimize the feature parameters. Optimal output value.

2. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 1, the RL circuit satisfies the leakage flow rate. With pressure difference Differential equations: ； in, This refers to the pressure difference between the input and output chambers of the ball valve. For leaked flow, It's the flu. For flow resistance, For time.

3. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 2, characterized in that, The influenza and flow resistance The influenza virus is determined based on the equivalent geometric dimensions of the leakage path and fluid property parameters. satisfy: ； The flow resistance satisfy: ； in, The equivalent length of the leakage path. The equivalent cross-sectional area of ​​the leakage path. The sealing contact width of the movable ring, The height of the sealing gap. This refers to the fluid dynamic viscosity.

4. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 2, the pressure difference head difference The conversion relationship is as follows: ； in, For fluid density, It is the acceleration due to gravity. This is due to head difference.

5. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 2, establishing the dynamic model of the moving ring includes establishing the resultant force acting on the moving ring. head difference Relationship: ； in, The net force on the moving ring, The water pressure in the input chamber, The water pressure in the output chamber. The effective pressure area of ​​the output chamber water pressure on the moving ring. The effective pressure area of ​​the input chamber water pressure on the moving ring. Let the pressure area of ​​the water pressure inside the valve cavity on the moving ring be such that it satisfies the following conditions: .

6. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 2, the displacement of the movable ring is obtained. head difference The relationship includes: ignoring the flow resistance Influenced by Newton's second law, the acceleration of the moving ring is integraled twice over time and simplified using fluid-structure interaction to obtain the following relationship: ； in, For the quality of the active ring, The bulk elastic modulus of water. For high-voltage side volume and satisfy ,in This is the activity loop.

7. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 3, the valve leakage flow rate head difference The dynamic relationship is as follows: ； in, For leaked flow, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. For fluid density, The bulk elastic modulus of water. For the quality of the active ring, Due to head difference, For influenza; characteristic parameters , The larger the value, the stronger the lag in the change of water pressure in the output chamber.

8. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 7, characterized in that, The derivation of the dynamic relationship uses the gap between the moving ring and the valve core. The gap Displacement of the moving ring satisfy: ； Valve leakage flow Through the gap Represented as: ； in, The gap between the moving ring and the valve core. For the displacement of the moving ring, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For valve diameter, It is the acceleration due to gravity. This is due to head difference.

9. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 7, characterized in that, The dynamic relation is expressed as: ； Intermediate coefficient , satisfy: ； ； in, With characteristic parameters It increases linearly.

10. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 4, establishing the pipeline water hammer wave propagation model using the method of characteristics includes: discretizing the pipeline as... Each computational unit takes a time step. ,in For spatial step size, Let be the water hammer wave velocity; the governing equation for the water hammer wave is: ； ； in, For the water head, The flow rate in the pipeline is equivalent to the leakage flow rate at the ball valve end. These are the position coordinates along the pipeline axis. For time, The cross-sectional area of ​​the pipe. For pipe diameter, This is the coefficient of friction.

11. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, Along the positive feature line The direction and the equation of the characteristic line are: ； Along the reverse feature line The direction and the equation of the characteristic line are: ； ； ； in, The number of computational units is [number]; the upstream boundary conditions are [conditions]. ,in For the head of the first node of the pipeline, The water head of the upstream reservoir.

12. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 11, characterized in that, The downstream boundary conditions are: ； in, For valve diameter, For the activity loop, The angle between the ball valve retaining ring and the vertical direction. For fluid density, It is the acceleration due to gravity. For the high-pressure side volume, This refers to the effective pressure-bearing area of ​​the output cavity. The bulk elastic modulus of water. For the quality of the active ring, It's influenza.

13. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 1, characterized in that, In step 5, the feature parameters are optimized using a genetic algorithm. This includes: setting the population size and crossover probability. and mutation probability Initialize the population and calculate individual fitness; generate offspring through selection, arithmetic crossover, and Gaussian mutation; merge the parent and offspring populations using an elitist retention strategy; set convergence criteria, iterate until convergence, and output the optimal value. value.

14. The coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory according to claim 13, characterized in that, The selection method uses a roulette wheel selection algorithm, and the convergence condition is: when continuous... The change in the fitness of the optimal individual over generations is less than the convergence threshold. Or the number of iterations reaches the maximum number of iterations. When the genetic algorithm has converged, the iteration is terminated.

15. A coupled modeling system for leaking ball valves in pumped-storage power stations based on circuit equivalence theory, used to execute the coupled modeling method for leaking ball valves in pumped-storage power stations based on circuit equivalence theory as described in any one of claims 1-14, characterized in that, It includes a leakage path equivalent modeling module, an active loop dynamics modeling module, a leakage dynamic relationship construction module, a water hammer wave propagation solution module, and a parameter optimization module; the leakage path equivalent modeling module is used to equivalently model the leakage path of the ball valve working seal as including the influenza virus. and flow resistance The RL circuit outputs leakage flow. With pressure difference Differential equations; The active ring dynamics modeling module is used to model based on pressure difference. The corresponding head difference establishes the active loop displacement. head difference The relationship is given, and the displacement of the active loop is output. ; The leakage dynamic relationship construction module is used to construct the dynamic relationship based on the displacement of the active ring. Build Leakage Flow head difference The dynamic relationship is used to determine the characteristic parameters. And output the dynamic relation, where For the high-voltage side volume; The water hammer wave propagation solver module is used to output leakage flow rate as a dynamic formula. As downstream boundary conditions, the characteristic line method is used to solve the pipeline water hammer wave propagation model, output the water head of each node in the pipeline and form the simulated pressure envelope. The parameter optimization module uses a genetic algorithm to optimize feature parameters, with the integral of the time-domain absolute error between the simulated and measured pressure envelopes as the fitness function. Optimal output Value and will be optimal The value is fed back to the leakage dynamic relation building module to update the dynamic relation.

16. A computer device, characterized in that, It includes a memory and a processor, which are interconnected and communicate with each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the coupling modeling method for leakage ball valves of pumped storage power stations based on circuit equivalence theory as described in any one of claims 1 to 14.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the coupling modeling method for leakage ball valves in pumped storage power stations based on circuit equivalence theory as described in any one of claims 1 to 14.

Images