Water turbine guide vane water leakage online calculation method and system

Abstract

The invention discloses an online calculation method and system for water leakage of a guide vane of a water turbine, and relates to the technical field of operation optimization and maintenance of a hydroelectric generating set. The relation between the unit angular velocity change rate and the water torque is constructed to output the unit guide vane water leakage amount; constructing a relational database of the water head, the water leakage and the speed reduction duration based on the water leakage effect; and outputting the water leakage amount of the unit through the water head value. According to the online calculation method for the water leakage of the guide vane of the water turbine, the water leakage of the guide vane of the water turbine is output by constructing the relation between the angular velocity change rate of the water turbine and the water torque, the high accuracy of performance analysis of the water turbine and the operation convenience are improved, and the monitoring and diagnosis capacity of the running state of the water turbine is improved; according to the water leakage monitoring and predicting method, better effects are achieved in the aspects of water leakage monitoring and predicting accuracy, reliability and monitoring efficiency.

Description

Technical Field

[0001] The 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 movable 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 leakage of guide vanes is of great significance.

[0003] At present, the measurement of movable guide vane leakage mostly adopts the volumetric method and the acoustic method. The volumetric method calculates the guide vane leakage by measuring the volume change rate of the fluid in the flow channel or vent when the upstream gate and guide vane of the unit are closed. It can only be carried out during the drainage and water filling stages of the unit maintenance, and it affects the maintenance period of the unit. The acoustic method requires the arrangement of an acoustic flow measurement probe in the unit flow channel to calculate the leakage by measuring the water flow velocity; in order to reduce the measurement error caused by the unstable water flow state, the length of the straight pipe section at the probe installation position should be 15 times or more of the pipe diameter. Under normal circumstances, when the movable guide vane is fully closed, the water flow velocity in the unit flow channel will be very low, resulting in a large error 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, and 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] In view of the technical problems existing in the current guide vane leakage measurement method, the present invention provides a method for online calculation of the guide vane leakage of a hydropower unit. Based on the unit design report, model test and type test data, the method constructs the functional relationship between the speed change rate and the water torque during the unit shutdown process, thereby online calculating and real-time monitoring the guide vane leakage of the unit. 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] In order to solve the above technical problems, the present invention provides the following technical solutions: an online calculation method for the guide vane leakage of a turbine, comprising collecting historical data during the shutdown process of the unit; constructing the relationship between the angular velocity change rate of the unit and the water torque to output the guide vane leakage of the unit; constructing a relationship database between the head, leakage and speed reduction time based on the leakage effect; and outputting the unit leakage through the head value.

[0009] As a preferred solution of the method for online calculation of water leakage of turbine guide vanes of the present invention, 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 rotation 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 the relationship data of water head, water leakage and speed reduction time and the speed reduction time record during the actual shutdown process.

[0010] As a preferred solution of the online calculation method 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 constructing a wind loss torque mathematical model, which is expressed as: , in, and To calculate the coefficient, is the wind resistance 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; Construct the mathematical model of bearing mechanical friction torque, which can be expressed as: , in, and are the initial friction moments of the guide bearing and thrust bearing, respectively, which can be measured and calculated through type tests. and They are the calculation coefficients of friction torque for guide bearing and thrust bearing respectively, usually taken as 2 and 1.5. is the bearing mechanical friction torque; Construct a mathematical model of mechanical braking torque, expressed as: , Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P qis the brake air 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.

[0011] 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.

[0012] The available formula is: , 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.

[0013] 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 hydraulic torque to output the unit guide vane leakage includes constructing a mathematical model of the unit angular velocity, which is expressed as: , in, is the initial angular velocity, is the angular acceleration, For time, is the angular velocity of the unit; Construct the mathematical model of the unit angular acceleration, expressed as: , in, is the unit's rotational inertia; The torque model and the angular velocity and acceleration models are combined and expressed as: , in, is the unit angular velocity.

[0014] As a preferred solution of the method for online calculation of water turbine guide vane leakage of the present invention, wherein: the relationship database of water head, water leakage and speed reduction time is constructed based on the effect of water leakage, including outputting the time dt when the speed of the unit drops from mechanical braking to the stop of the unit under the effect of water leakage at each water head, creating a relationship database of water head, water leakage and speed reduction time, and the speed reduction time is expressed as: , 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; The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, expressed as: , in, and is 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.

[0015] 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: , 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; The numerical method is used to output the predicted leakage, which is expressed as: , 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 Update through iteration , until satisfied Or the maximum number of iterations is reached, output The minimum value of , is the predicted value of water leakage.

[0016] 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.

[0017] As a preferred solution of the online calculation system for water 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, water head and leakage; the leakage prediction module is used to predict leakage.

[0018] A computer device comprises 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 turbine guide vane leakage.

[0019] 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.

[0020] Beneficial effects of the present invention: The online calculation method for the guide vane leakage of a turbine provided by the present invention outputs the guide vane leakage of the unit by constructing the relationship between the angular velocity change rate 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 turbine performance analysis and the convenience of operation, improving the monitoring and diagnosis capabilities of the unit operating status, and improving the operating efficiency and reliability of the unit. A relationship database of head, leakage and speed reduction duration 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 unit leakage is output through the head value, which improves the timeliness and accuracy of turbine maintenance, reduces losses and maintenance costs caused by leakage, and increases the stability and safety of power generation. The present invention achieves better results in terms of accuracy, reliability and monitoring efficiency of leakage monitoring and prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 An overall flow chart of an online calculation method for water turbine guide vane leakage provided by the first embodiment of the present invention.

[0023] 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.

[0024] Figure 3 The present invention provides an overall flow chart of an online calculation system for water turbine guide vane leakage provided by the third embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0026] Example 1 Reference Figure 1-Figure 2 , which is an embodiment of the present invention, provides an online calculation method for water leakage of a turbine guide vane, comprising: S1: Collect historical data of the unit shutdown process.

[0027] Furthermore, torque data, water torque data, speed drop time data, database construction and water leakage prediction data are collected; The torque data includes rotation 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 the relationship data of water head, water leakage and speed reduction time and the speed reduction time record during the actual shutdown process.

[0028] 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.

[0029] Calculation coefficientsThese coefficients are crucial in determining the exact relationship between the windage moment and the mechanical friction moment.

[0030] The initial friction torque is the starting value for calculating the mechanical friction torque and can be obtained by type test measurement.

[0031] 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.

[0032] 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.

[0033] The model test and CFD analysis results, the data obtained through these analyses can help determine the relationship curve between hydraulic torque and water head, leakage and rotation speed.

[0034] The moment of inertia means that the calculation of angular acceleration requires the moment of inertia of the system.

[0035] The actual speed change data is the change of 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.

[0036] 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.

[0037] 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.

[0038] S2: Construct the relationship between the unit angular velocity change rate and the water torque to output the unit guide vane leakage.

[0039] Furthermore, a mathematical model of wind loss moment is constructed, which is expressed as: , in, and To calculate the coefficient, is the wind resistance 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; Construct the mathematical model of bearing mechanical friction torque, which can be expressed as: , in, and are the initial friction moments of the guide bearing and thrust bearing, respectively, which can be measured and calculated through type tests. and They are the calculation coefficients of friction torque for guide bearing and thrust bearing respectively, usually taken as 2 and 1.5. is the mechanical friction torque of the bearing.

[0040] Construct a mathematical model of mechanical braking torque, expressed as: , Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P q is the brake air 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.

[0041] It should be noted that the hydraulic 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: , 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.

[0042] It should also be noted that the mathematical model of the unit angular velocity is constructed as follows: , in, is the initial angular velocity, is the angular acceleration, For time, is the angular velocity of the unit; Construct the mathematical model of the unit angular acceleration, expressed as: , in, is the unit's rotational inertia; The torque model and the angular velocity and acceleration models are combined and expressed as: , in, is the unit angular velocity.

[0043] Since the amount of water leakage from the movable guide vanes will affect the amount of water 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 the duration and the amount of water leakage from the movable guide vanes, the current guide vane leakage status of the unit can be accurately evaluated.

[0044] S3: Construct a relational database of water head, leakage and speed reduction duration based on the effect of leakage.

[0045] 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.

[0046] 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: , 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; The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, expressed as: , in, and is 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.

[0047] S4: Output the unit leakage through the head value.

[0048] Furthermore, according to the time it takes for the rotation 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.

[0049] It should be noted that the mathematical model for predicting water leakage is constructed as follows: , 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; The numerical method is used to output the predicted leakage, which is expressed as: , 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 Update through iteration , until satisfied Or the maximum number of iterations is reached, output The minimum value of , is the predicted value of water leakage.

[0050] Example 2 An embodiment of the present invention provides an online calculation method for water turbine guide vane leakage. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0051] First, an experiment was designed to measure and convert the guide vane leakage under different water heads using traditional methods during the unit overhaul and water filling period, and calculate the real-time guide vane leakage online based on the historical data of the unit shutdown process within one week after the unit was repaired. Since the unit was put into operation very quickly after the repair, it can be assumed that the guide vane leakage after the repair is exactly the same as that during the unit overhaul and water filling period. The experiment was divided into a test group and a control group. The test group applied the proposed invention content, while the control group used the existing leakage monitoring technology.

[0052] Data collection: collect historical data of the unit shutdown process, including but not limited to parameters such as speed, water head, and water leakage.

[0053] Build a relationship model: Test group: Using the collected data, a mathematical model of the relationship between the unit's angular velocity change rate and the water torque was constructed, and the real-time water leakage of the unit's guide vanes was output.

[0054] Control group: The existing technology was applied, mainly relying on the traditional physical measurement method during unit maintenance, and failed to calculate the water leakage in real time.

[0055] Relational database construction: 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.

[0056] Control group: The existing data recording method was used, and no relational database was formed for rapid prediction of water leakage.

[0057] Water leakage prediction: Test group: Through the water head value, using the constructed database and model, the water leakage of the unit is output in real time.

[0058] Control group: Relying on traditional methods, it is impossible to estimate the real-time water leakage.

[0059] Table 1 Experimental results , From the above experiments, it can be seen that the invented method used by the test group is significantly better than the existing technology used by the control group in predicting water leakage. The error between the predicted results of the test group and the measured values ​​is very small, with the maximum deviation not exceeding 5%, while the control group cannot calculate the real-time water leakage, which shows that the proposed online calculation method has significant advantages in accuracy and real-time performance.

[0060] By building a relationship between the unit's angular velocity change rate and the hydraulic torque, and a database of the relationship between the head, leakage, and deceleration time based on the effect of leakage, the test team was able to accurately predict the leakage of the turbine guide vanes in real time. This not only improves monitoring efficiency, but also allows operation and maintenance personnel to make timely adjustment and maintenance decisions, avoiding unit shutdown difficulties and shutdown creep due to excessive leakage, leading to abnormal wear of the thrust bearing, and threatening the safe operation of the unit.

[0061] In contrast, the existing technology in the control group cannot predict the change of guide vane leakage during the operation of the unit due to the lack of accurate modeling and real-time data analysis capabilities for the dynamic relationship of the complex system. This gap illustrates the technical innovation and novelty of the invention content, as well as its significant beneficial effects in improving the accuracy, reliability and efficiency of turbine leakage monitoring and prediction.

[0062] In general, the present invention achieves better results in terms of accuracy, reliability and monitoring efficiency of water leakage monitoring and prediction.

[0063] Example 3 Reference Figure 3 , which is an embodiment of the present invention, provides an online calculation system for water turbine guide vane leakage, including an initialization module, a unit angular velocity model construction module, a water leakage relationship database construction module, and a water leakage prediction module.

[0064] 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, water head and leakage, and the leakage prediction module is used to predict the leakage. If the function is implemented in the form of 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 part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0065] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0066] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk case (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a 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, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0067] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logical function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 angular velocity change rate and the water torque to output the unit guide vane leakage; Based on the effect of water leakage, a relational database of water head, water leakage and speed reduction duration is constructed; The water leakage of the unit is output through the head value.

2. The method for online calculation of water 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 rotation 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 the relationship data of water head, water leakage and speed reduction time and the speed reduction time record during the 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: ， in, and To calculate the coefficient, is the wind resistance 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; Construct the mathematical model of bearing mechanical friction torque, which can be expressed as: ， in, and are the initial friction moments of the guide bearing and thrust bearing, respectively, which can be measured and calculated through type tests. and They are the calculation coefficients of friction torque for guide bearing and thrust bearing respectively, usually taken as 2 and 1.

5. is the bearing mechanical friction torque; Construct a mathematical model of mechanical braking torque, expressed as: ， Where Z is the number of mechanical brakes, μ is the braking friction coefficient, P q is the brake air 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 the model test and CFD analysis. rem The relationship curve between water head H, water leakage Q and speed n is expressed as: ， 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.

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: ， in, is the initial angular velocity, is the angular acceleration, For time, is the angular velocity of the unit; Construct the mathematical model of the unit angular acceleration, expressed as: ， in, is the unit's rotational inertia; The torque model and the angular velocity and acceleration models are combined and expressed as: ， in, is the unit angular velocity.

6. The method for online calculation of water turbine guide vane leakage according to claim 5, characterized in that: The construction of the 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 brake input to unit stop rotation 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, 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; The system dynamics reflects the interaction between hydraulic torque, speed, head and leakage, expressed as: ， in, and is 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.

7. The method for online calculation of water turbine guide vane leakage according to claim 6, characterized in that: 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: ， 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; The numerical method is used to output the predicted leakage, which is expressed as: ， 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 Update through iteration , until satisfied Or the maximum number of iterations is reached, output The minimum value of , is the predicted value of water leakage.

8. A system using the method for online calculation of water turbine guide vane leakage as claimed in any one of claims 1 to 7, characterized in that: It includes an initialization module, a unit angular velocity model building module, a water leakage relation database building module, and a 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 rotation speed change; The water leakage relation database construction module is used to reflect the interaction between hydraulic torque, rotation speed, water head and water leakage; The water leakage prediction module is used to predict the water leakage.

9. 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 7 are implemented.

10. 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 7 are implemented.

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