A method and system for online calculation of water leakage of turbine guide vanes

Abstract

The present invention discloses a method and system for online calculation of turbine guide vane leakage, relating to the technical field of operation optimization and maintenance of hydroelectric generator sets. The method comprises collecting historical data of the unit's shutdown process; establishing a relationship between the unit's angular velocity change rate and hydraulic torque to output the unit's guide vane leakage; constructing a database of relationships between head, leakage, and deceleration duration based on the leakage effect; and outputting the unit's leakage using the head value. The method for online calculation of turbine guide vane leakage provided by the present invention outputs the unit's guide vane leakage by establishing a relationship between the unit's angular velocity change rate and hydraulic torque, thereby improving the accuracy of turbine performance analysis and the ease of operation, enhancing the monitoring and diagnosis capabilities of the unit's operating status, and increasing the unit's operating efficiency and reliability. The present invention achieves improved results in terms of the accuracy, reliability, and monitoring efficiency of leakage monitoring and prediction.

Description

Technical Field

[0001] The present invention relates to the technical field of operation optimization and maintenance of a hydroelectric generator set, and in particular to an online calculation method and system for water leakage of a turbine guide vane. Background Art

[0002] The leakage of turbine guide vanes is an important indicator for evaluating the manufacturing, installation, maintenance quality and operating status of turbine generator sets. Excessive leakage not only affects the water energy utilization and economic operation of the power station, but also aggravates the cavitation damage of the guide vane sealing surface gap, and even causes difficulty in shutting down the unit and shutdown creep, resulting in abnormal wear of the thrust bearing and threatening the safe operation of the unit. Therefore, measuring the guide vane leakage is of great significance.

[0003] Currently, the measurement of guide vane leakage is mostly done using the volumetric and acoustic methods. The volumetric method calculates guide vane leakage by measuring the rate of change of fluid volume in the flow channel or vent when the upstream gates and guide vanes of the unit are closed. This method can only be performed during the drainage and water filling stages of unit maintenance, and affects the unit maintenance schedule. The acoustic method requires the placement of an acoustic flow probe in the unit flow channel to calculate the leakage by measuring the water flow velocity. To reduce measurement errors caused by unstable water flow patterns, the length of the straight pipe section at the probe installation location should be 15 times or more of the pipe diameter. Generally, when the guide vanes are fully closed, the water flow velocity in the unit flow channel will be very low, resulting in large errors in the measured leakage.

[0004] The acoustic method for measuring guide vane leakage not only requires the arrangement of measuring devices in the flow channel in advance, but also the measurement accuracy does not meet the requirements; the volumetric method for measuring guide vane leakage requires closing the upstream gate of the unit. The measurement conditions are only available during the annual maintenance of the unit. It is impossible to monitor the changes in guide vane leakage after the unit is repaired, which is not conducive to the formulation of maintenance plans related to guide vane sealing treatment and affects the smooth implementation of unit status maintenance.

[0005] To address the technical issues existing in current methods for measuring guide vane leakage, this paper provides a method for online calculation of guide vane leakage in hydropower units. Based on unit design reports, model test data, and type test data, this method constructs a functional relationship between the rate of change of speed during unit shutdown and the hydraulic torque, thereby enabling online calculation and real-time monitoring of guide vane leakage. Summary of the Invention

[0006] In view of the above-mentioned problems, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is that the existing leakage measurement method can only be carried out during the drainage and water filling stages of the unit maintenance. For the maintenance unit without opening the volute door, the leakage of the upstream gate cannot be measured, which will affect the measurement accuracy of the leakage.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: an online calculation method for turbine guide vane leakage, comprising collecting historical data during unit shutdown; constructing a relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage; constructing a relationship database among water head, water leakage and deceleration time based on the effect of water leakage; and outputting the unit leakage through the water head value.

[0009] As a preferred solution of the method for online calculation of water leakage of turbine guide vanes according to the present invention, the method comprises: collecting historical data during the shutdown process of the unit, including collecting torque data, water torque data, speed drop time data, database construction and water leakage prediction data;

[0010] The torque data includes rotational speed, calculation coefficient and initial friction torque;

[0011] The water moment data include water head and water leakage;

[0012] The speed drop time data includes rotational inertia and actual speed change data;

[0013] The database construction and water leakage prediction data include relationship data of water head, water leakage and speed reduction time and speed reduction time record during actual shutdown process.

[0014] As a preferred solution of the method for online calculation of turbine guide vane leakage of the present invention, wherein: the step of constructing the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage includes constructing a wind loss torque mathematical model, which is expressed as:

[0015] ,

[0016] in, and To calculate the coefficient, is the windage torque at rated speed of the unit, which can be measured and calculated through type test. Usually take 3, is the unit speed, is the wind loss moment;

[0017] Construct a mathematical model of the bearing mechanical friction torque, which can be expressed as:

[0018] ,

[0019] in, and are the initial friction torques of the guide bearing and thrust bearing respectively, which can be measured and calculated through type test. and are the calculation coefficients of friction torque of guide bearing and thrust bearing respectively, usually taken as 2 and 1.5, is the bearing mechanical friction torque;

[0020] Construct a mathematical model of mechanical braking torque, which can be expressed as:

[0021] ,

[0022] Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P q is the brake pressure, A q Cross-sectional area of a single mechanical brake cylinder, r m is the brake distribution radius, T jx is the mechanical braking torque.

[0023] As a preferred solution of the method for online calculation of turbine guide vane leakage of the present invention, wherein: the construction of the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage includes outputting the water torque M based on model test and CFD analysis. rem The relationship curve between water head H, water leakage Q and speed n is as follows Figure 2 As shown. Among them, represents the residual torque (braking effect), represents the residual torque (driving action), represents the equilibrium speed, Indicates rated speed.

[0024] The available formula is:

[0025] ,

[0026] in, is the water resistance torque at rated speed, ef3 is the calculation coefficient, is the leakage torque, M rem is the output water torque.

[0027] As a preferred solution of the method for online calculation of turbine guide vane leakage of the present invention, wherein: the step of constructing the relationship between the unit angular velocity change rate and the hydraulic torque to output the unit guide vane leakage includes constructing a mathematical model of the unit angular velocity, which is expressed as:

[0028] ,

[0029] in, is the initial angular velocity, is the angular acceleration, For time, is the angular velocity of the unit;

[0030] Construct the mathematical model of the unit angular acceleration, which can be expressed as:

[0031] ,

[0032] in, is the unit's rotational inertia;

[0033] The torque model and the angular velocity and acceleration models are combined and expressed as:

[0034] ,

[0035] in, is the unit angular velocity.

[0036] As a preferred solution of the method for online calculation of turbine guide vane leakage of the present invention, the method of constructing a relational database of water head, leakage and speed reduction time based on the effect of leakage includes outputting the time dt when the speed of the unit drops from the mechanical brake input to the unit stopping rotation under the effect of leakage at each water head, creating a relational database of water head, leakage and speed reduction time, and the speed reduction time is expressed as:

[0037] ,

[0038] in, is the rate of change of the state vector over time, is the dynamic state of the system, Indicates water head, water leakage and speed, represents the linear part of the system dynamics, Represents the nonlinear part of the system dynamics;

[0039] The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, which can be expressed as:

[0040] ,

[0041] in, and are the Fourier transform and inverse Fourier transform, for The inverse operation of represents the water head, water leakage and speed after Fourier transformation, Indicates the starting speed during the unit shutdown process. Indicates the final speed during the unit shutdown process.

[0042] As a preferred solution of the method for online calculation of turbine guide vane leakage of the present invention, the method of outputting the unit leakage through the head value includes constructing a mathematical model for predicting leakage, which is expressed as:

[0043] ,

[0044] in, For the optimal water leakage, To minimize the objective function, According to the water head and the assumed leakage Predicted deceleration time, Indicates that it corresponds to The observed deceleration time, represents the regularization term, represents the regularization parameter, which is used to control the strength of the regularization term;

[0045] The numerical method is used to output the predicted leakage, which is expressed as:

[0046] ,

[0047] in, For the iteration step The predicted value of water leakage, is the step length, Table i is the objective function in The gradient at

[0048] Update through iteration , until satisfied Or the maximum number of iterations is reached, output The minimum value of , which is the predicted value of water leakage.

[0049] Another object of the present invention is to provide an online calculation system for turbine guide vane leakage, which can output the unit leakage through the head value, solving the problem of low accuracy of current leakage measurement, including leakage monitoring and prediction.

[0050] As a preferred solution of the online calculation system for turbine guide vane leakage described in the present invention, it includes: an initialization module, a unit angular velocity model construction module, a leakage relationship database construction module, and a leakage prediction module; the initialization module is used to collect historical data of the unit shutdown process; the unit angular velocity model construction module is used to construct the relationship between leakage and speed change; the leakage relationship database construction module is used to reflect the interaction between water torque, speed, head and leakage; and the leakage prediction module is used to predict leakage.

[0051] A computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement a step of an online calculation method for water leakage of a turbine guide vane.

[0052] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of an online calculation method for water leakage of a turbine guide vane.

[0053] Beneficial effects of the present invention: The online calculation method for the water leakage of the guide vane of the turbine provided by the present invention outputs the water leakage of the guide vane of the unit by constructing the relationship between the rate of change of the angular velocity of the unit and the water torque, thereby realizing an accurate description of the torque change of the unit under different operating conditions, improving the high accuracy of the performance analysis of the turbine and the convenience of operation, improving the monitoring and diagnosis capabilities of the operating status of the unit, and improving the operating efficiency and reliability of the unit. A relationship database of head, leakage and speed reduction time is constructed based on the effect of leakage, which can quickly find and predict leakage conditions and possible performance changes under specific head conditions, thereby optimizing operating strategies and planning maintenance work in advance, reducing the risk of unexpected shutdowns, and ensuring the maximization of power generation efficiency. The water leakage of the unit is output through the head value, which improves the timeliness and accuracy of turbine maintenance, reduces the losses and maintenance costs caused by leakage, and increases the stability and safety of power generation. The present invention achieves better results in the accuracy, reliability and monitoring efficiency of leakage monitoring and prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only 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.

[0055] Figure 1 This is an overall flow chart of an online calculation method for turbine guide vane leakage provided by the first embodiment of the present invention.

[0056] Figure 2 The first embodiment of the present invention provides an online calculation method for the water leakage of a turbine guide vane based on the output water moment M of the model test and CFD analysis. rem Relationship curve between water head H, water leakage Q and rotation speed n.

[0057] Figure 3 This is an overall flow chart of an online calculation system for turbine guide vane leakage provided by the third embodiment of the present invention. DETAILED DESCRIPTION

[0058] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0059] Example 1

[0060] Reference Figure 1-Figure 2 , as one embodiment of the present invention, provides an online calculation method for water leakage of a turbine guide vane, comprising:

[0061] S1: Collect historical data of the unit shutdown process.

[0062] Furthermore, torque data, water torque data, speed drop time data, database construction and water leakage prediction data are collected;

[0063] The torque data includes rotational speed, calculation coefficient and initial friction torque;

[0064] The water moment data include water head and water leakage;

[0065] The speed drop time data includes rotational inertia and actual speed change data;

[0066] The database construction and water leakage prediction data include relationship data of water head, water leakage and speed reduction time and speed reduction time record during actual shutdown process.

[0067] It should be noted that the rotational speed refers to the rotational speed data of the rotating parts at different time points, which is the basis for calculating the wind loss torque, mechanical friction torque and water torque.

[0068] Calculation coefficientsThese coefficients are crucial in determining the specific relationship between the windage torque and the mechanical friction torque.

[0069] The initial friction torque is the starting value for calculating the mechanical friction torque and can be obtained through type test measurement.

[0070] The calculation of hydraulic torque requires knowledge of the size of the water head, which directly affects the operating status of the hydroelectric generator set.

[0071] The water leakage is the amount of water leakage after the guide vane is closed, which is of great significance for the accurate calculation of water torque.

[0072] The results of model tests and CFD analysis can help determine the relationship curves between hydraulic torque and water head, leakage and rotation speed.

[0073] The moment of inertia indicates that the calculation of angular acceleration requires the knowledge of the system's moment of inertia.

[0074] The actual speed change data is the change in speed over time recorded in actual operation, which is used to compare with the theoretical calculation and then determine the coefficients in the theoretical formula.

[0075] The relationship data between water head, water leakage and speed reduction time are obtained through experiments or field measurements and are used to construct a relational database.

[0076] The speed drop time during the actual shutdown process is recorded as the time from when the unit speed drops from the mechanical brake input to when the unit stops rotating in actual operation, which is used to match with the data in the database to predict the current water leakage.

[0077] S2: Construct the relationship between the unit's angular velocity change rate and the water torque to output the unit's guide vane leakage.

[0078] Furthermore, a mathematical model of wind loss moment is constructed, which is expressed as:

[0079] ,

[0080] in, and To calculate the coefficient, is the windage torque at rated speed of the unit, which can be measured and calculated through type test. Usually take 3, is the unit speed, is the wind loss moment;

[0081] Construct a mathematical model of the bearing mechanical friction torque, which can be expressed as:

[0082] ,

[0083] in, and are the initial friction torques of the guide bearing and thrust bearing respectively, which can be measured and calculated through type test. and are the calculation coefficients of friction torque of guide bearing and thrust bearing respectively, usually taken as 2 and 1.5, is the mechanical friction torque of the bearing.

[0084] Construct a mathematical model of mechanical braking torque, which can be expressed as:

[0085] ,

[0086] Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P q is the brake pressure, A q Cross-sectional area of a single mechanical brake cylinder, r m is the brake distribution radius, T jx is the mechanical braking torque.

[0087] It should be noted that the water moment M is output based on the model test and CFD analysis. rem The relationship curve between water head H, water leakage Q and speed n is expressed as:

[0088] ,

[0089] in, is the water resistance torque at rated speed, ef3 is the calculation coefficient, is the leakage torque, M rem is the output water torque.

[0090] It should also be noted that the mathematical model of the unit angular velocity is constructed as follows:

[0091] ,

[0092] in, is the initial angular velocity, is the angular acceleration, For time, is the angular velocity of the unit;

[0093] Construct the mathematical model of the unit angular acceleration, which can be expressed as:

[0094] ,

[0095] in, is the unit's rotational inertia;

[0096] The torque model and the angular velocity and acceleration models are combined and expressed as:

[0097] ,

[0098] in, is the unit angular velocity.

[0099] Since the amount of water leakage from the movable guide vanes will affect the amount of hydraulic torque acting on the rotating parts of the unit, the duration of the rotating parts' speed drop after the movable guide vanes are fully closed during the unit's shutdown process is monitored. Based on the relationship curve between this duration and the amount of water leakage from the movable guide vanes, the current guide vane leakage status of the unit can be accurately assessed.

[0100] S3: Based on the effect of water leakage, a relational database of water head, water leakage and speed reduction duration is constructed.

[0101] Furthermore, by performing calculus on the above formula, we can solve the time dt for the unit speed to drop from mechanical braking to unit stopping under the action of leakage at various water heads, thereby creating a relationship database between water head, leakage and speed reduction time.

[0102] It should be noted that the time dt from the mechanical brake input to the unit stopping rotation under the action of water leakage at each water head is output, and a relationship database of water head, water leakage and speed reduction time is created. The speed reduction time is expressed as:

[0103] ,

[0104] in, is the rate of change of the state vector over time, is the dynamic state of the system, Indicates water head, water leakage and speed, represents the linear part of the system dynamics, Represents the nonlinear part of the system dynamics;

[0105] The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, which can be expressed as:

[0106] ,

[0107] in, and are the Fourier transform and inverse Fourier transform, for The inverse operation of represents the water head, water leakage and speed after Fourier transformation, Indicates the starting speed during the unit shutdown process. Indicates the final speed during the unit shutdown process.

[0108] S4: Output the water leakage of the unit through the head value.

[0109] Furthermore, according to the time it takes for the speed to drop due to mechanical braking and for the unit to stop rotating during the actual shutdown process of the unit, combined with the current water head value, the current water leakage of the unit can be interpolated in the database.

[0110] It should be noted that the mathematical model for predicting water leakage is constructed as follows:

[0111] ,

[0112] in, For the optimal water leakage, To minimize the objective function, According to the water head and the assumed leakage Predicted deceleration time, Indicates that it corresponds to The observed deceleration time, represents the regularization term, represents the regularization parameter, which is used to control the strength of the regularization term;

[0113] The numerical method is used to output the predicted leakage, which is expressed as:

[0114] ,

[0115] in, For the iteration step The predicted value of water leakage, is the step length, Table i is the objective function in The gradient at

[0116] Update through iteration , until satisfied Or the maximum number of iterations is reached, output The minimum value of , which is the predicted value of water leakage.

[0117] Example 2

[0118] One embodiment of the present invention provides an online calculation method for turbine guide vane leakage. To verify the beneficial effects of the present invention, scientific demonstration is conducted through economic benefit calculation and simulation experiments.

[0119] First, an experiment was designed. During the unit's overhaul and water filling period, traditional methods were used to measure and convert guide vane leakage at different water heads. Real-time guide vane leakage was then calculated online one week after the unit repair based on historical data from the unit's downtime. Because the unit was operational very quickly after the repair, it was assumed that the guide vane leakage after the repair was identical to that during the overhaul and water filling period. The experiment was divided into a test group and a control group. The test group applied the proposed invention, while the control group used existing leakage monitoring technology.

[0120] Data collection: collect historical data of the unit shutdown process, including but not limited to parameters such as speed, water head, and water leakage.

[0121] Build a relationship model:

[0122] Test team: Using the collected data, a mathematical model of the relationship between the unit's angular velocity change rate and water torque was constructed, and the real-time leakage of the unit's guide vanes was output.

[0123] Control group: Using existing technology, it mainly relied on the traditional physical measurement method during unit maintenance and failed to calculate the water leakage in real time.

[0124] Relational database construction:

[0125] Test group: Based on the effect of water leakage, a database containing the relationship between water head, water leakage and speed reduction time was constructed to predict and verify water leakage.

[0126] Control group: The existing data recording method was used, and no relational database was formed for rapid prediction of water leakage.

[0127] Water leakage prediction:

[0128] Test group: Through the water head value, using the constructed database and model, the water leakage of the unit is output in real time.

[0129] Control group: Relying on traditional methods, it is impossible to estimate the real-time water leakage.

[0130] Table 1 Experimental results

[0131] ,

[0132] The above experiments demonstrate that the inventive method used by the test group significantly outperforms the existing technology used by the control group in predicting water leakage. The error between the test group's predictions and the measured values was minimal, with the maximum deviation not exceeding 5%. However, the control group was unable to calculate the real-time water leakage. This demonstrates the significant advantages of the proposed online calculation method in terms of accuracy and real-time performance.

[0133] By establishing a relationship between the unit's angular velocity change rate and hydraulic torque, and building a database of relationships between head, leakage, and deceleration duration based on leakage, the test team was able to accurately predict turbine guide vane leakage in real time. This not only improves monitoring efficiency but also allows operations and maintenance personnel to make timely adjustments and repairs, avoiding the difficulties and creep caused by excessive leakage that can lead to abnormal wear of thrust bearings and threaten safe operation of the unit.

[0134] In contrast, the existing technology in the control group, lacking the ability to accurately model complex system dynamics and conduct real-time data analysis, was unable to predict changes in guide vane leakage during unit operation. This gap demonstrates the technical innovation and novelty of the invention, as well as its significant benefits in improving the accuracy, reliability, and efficiency of turbine leakage monitoring and prediction.

[0135] In general, the present invention achieves better results in terms of accuracy, reliability and monitoring efficiency of water leakage monitoring and prediction.

[0136] Example 3

[0137] Reference Figure 3 , which is an embodiment of the present invention, provides an online calculation system for turbine guide vane leakage, including an initialization module, a unit angular velocity model construction module, a leakage relationship database construction module, and a leakage prediction module.

[0138] The initialization module is used to collect historical data of the unit shutdown process, the unit angular velocity model construction module is used to construct the relationship between leakage and speed change, the leakage relationship database construction module is used to reflect the interaction between water torque, speed, head and leakage, and the leakage prediction module is used to predict the leakage.

[0139] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0140] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0141] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting, or processing it in another suitable manner as necessary, and then storing it in a computer memory.

[0142] It should be understood that various aspects of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one or a combination of the following technologies known in the art may be used: a discrete logic circuit having logic gates for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gates, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc. It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to be limiting. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and such modifications are intended to be encompassed by the claims of the present invention.

[0143] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An online calculation method for water turbine guide vane leakage, characterized in that: include: Collect historical data of unit shutdown process; Construct the relationship between the unit's angular velocity change rate and the water torque to output the unit's guide vane leakage; Based on the effect of water leakage, a relational database of water head, water leakage and speed reduction duration is constructed; Output the water leakage of the unit through the water head value; The method of constructing a relational database of water head, water leakage and speed reduction duration based on the effect of water leakage includes outputting the time dt of the unit speed dropping from mechanical braking to unit stopping under the effect of water leakage at each water head, creating a relational database of water head, water leakage and speed reduction duration, and the speed reduction time is expressed as: in, is the rate of change of the state vector over time, y is the dynamic state of the system, H, Q l , n represents water head, water leakage and speed, represents the linear part of the system dynamics, F(H,Q l ,n,y) represents the nonlinear part of the system dynamics; The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, which can be expressed as: in, and is the inverse Fourier transform and the Fourier transform, for The inverse operation of It represents the water head, water leakage and speed after Fourier transformation, n0 represents the starting speed during the unit shutdown process, n f Indicates the final speed during the unit shutdown process; Outputting the water leakage of the unit through the water head value includes constructing a mathematical model for predicting water leakage, which is expressed as: Among them, J(Q l ) is the optimal leakage, To minimize the objective function, dt pred (H i ,Q l,i ) indicates the water head H i and the assumed leakage Q l,i Predicted deceleration time, dt obs,i Indicates that it corresponds to H i The observed deceleration time, R(Q l ) represents the regularization term, λ represents the regularization parameter, which is used to control the strength of the regularization term; The numerical method is used to output the predicted leakage, which is expressed as: in, is the predicted value of water leakage at iteration step k, α k is the step length, Indicates that the objective function is The gradient at Update through iteration Until satisfied Or the maximum number of iterations is reached, output J(Q l ) of the minimum value of Q l , which is the predicted value of water leakage.

2. The method for online calculation of turbine guide vane leakage according to claim 1, characterized in that: The historical data collected during the shutdown process of the unit includes collecting torque data, water torque data, speed drop time data, database construction and water leakage prediction data; The torque data includes rotational speed, calculation coefficient and initial friction torque; The water moment data include water head and water leakage; The speed drop time data includes rotational inertia and actual speed change data; The database construction and water leakage prediction data include relationship data of water head, water leakage and speed reduction time and speed reduction time record during actual shutdown process.

3. The method for online calculation of water turbine guide vane leakage according to claim 2, characterized in that: The method of constructing the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage includes constructing a wind loss torque mathematical model, which is expressed as: T v =K v ×n ev Among them, K v and ev are calculation coefficients, K v is the wind resistance torque at rated speed of the unit, which can be measured and calculated through type test. ev is 3, n is the unit speed, T v is the wind loss moment; Construct a mathematical model of the bearing mechanical friction torque, which can be expressed as: T zc =K d ×n ef1 +K t ×n ef2 Among them, K d and K t They are the initial friction torques of the guide bearing and thrust bearing respectively, which can be measured and calculated through type test. ef1 and ef2 are the calculation coefficients of the friction torques of the guide bearing and thrust bearing respectively, which are 2 and 1.

5. T zc is the bearing mechanical friction torque; Construct a mathematical model of mechanical braking torque, which can be expressed as: T jx =Z×μ×P q ×A q ×r m Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P q is the brake pressure, A q Cross-sectional area of a single mechanical brake cylinder, r m is the brake distribution radius, T jx is the mechanical braking torque.

4. The method for online calculation of water turbine guide vane leakage according to claim 3, characterized in that: The method of constructing the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage includes outputting the water torque M based on model test and CFD analysis. rem The relationship curve between water head H, water leakage Q and speed n is expressed as: M rem =T szN ×n ef3 +T ls (Q,H) Among them, T szN is the water resistance torque at rated speed, ef3 is the calculation coefficient, T ls (Q, H) is the leakage torque, M rem is the output water torque.

5. The method for online calculation of water turbine guide vane leakage according to claim 4, characterized in that: The method of constructing the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage includes constructing a mathematical model of the unit angular velocity, which is expressed as: ω=ω0+ε×t Where, ω0 is the initial angular velocity, ε is the angular acceleration, t is the time, and ω is the angular velocity of the unit; Construct the mathematical model of the unit angular acceleration, which can be expressed as: ε=(M rem -T v -T zc -T jx ) / J Wherein, J is the moment of inertia of the unit; The torque model and the angular velocity and acceleration models are combined and expressed as: ω=ω0+(M rem -T v -T zc -T jx ) / J×t Where ω is the angular velocity of the unit.

6. A system using the method for online calculation of turbine guide vane leakage according to any one of claims 1 to 5, characterized in that: It includes initialization module, unit angular velocity model construction module, water leakage relation database construction module, and water leakage prediction module; The initialization module is used to collect historical data of the unit shutdown process; The unit angular velocity model building module is used to build the relationship between water leakage and speed change; The water leakage relationship database construction module is used to reflect the interaction between water torque, rotation speed, water head and water leakage; The water leakage prediction module is used to predict the water leakage.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method for online calculation of water leakage of a turbine guide vane according to any one of claims 1 to 5 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for online calculation of water leakage of a turbine guide vane according to any one of claims 1 to 5 are implemented.

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