CN118549060A - Online calculation method and system for air leakage of hydropower station braking air utilization system - Google Patents
Online calculation method and system for air leakage of hydropower station braking air utilization system Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/28—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds
- G01M3/2876—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/02—Fluid pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses an online calculation method and an online calculation system for air leakage of a gas system for hydroelectric power station braking, which relate to the technical field of operation and maintenance of hydroelectric power stations and comprise the steps of calculating the cavity volume when a mechanical braking device of a single unit is put in and out, judging the running state of an air compressor of the gas system for braking based on the cavity volume, and determining the starting condition of an air leakage calculation flow; calculating the starting interval time of the air compressor and the compressed air variable quantity of an air storage tank of a braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank; the pressure change is monitored, and the air leakage of the braking air system is calculated by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of each unit.
Description
Technical Field
The invention relates to the technical field of hydropower station operation and maintenance, in particular to an online calculation method for air leakage of a hydropower station braking air system.
Background
The hydraulic power station braking gas utilization system is composed of an air compressor, a gas storage tank, a drying device, pipeline accessories and the like, and is mainly used for providing a gas source for the switching of a mechanical braking device of a unit, reducing the time of the stopping process of the unit, avoiding damage to a thrust bearing caused by long-time sliding, and eliminating the risk of stopping peristaltic motion of the unit, wherein the gas leakage is an important index for evaluating the health condition of the braking gas utilization system.
At present, the air leakage condition of the air system for braking is mainly judged by manual inspection and comparison of the starting and stopping interval duration of the air compressor. The manual inspection method is mainly used for inspecting the air leakage condition of the braking system by periodically assigning technicians to inspect equipment and pipelines related to the braking air system and users, and judging whether the system has abnormal air leakage or not through obvious air leakage points found by inspection. The method for judging the air leakage condition of the braking air system by comparing the start-stop time intervals of the air compressors is mainly characterized in that whether the system has abnormal air leakage is reflected by calculating the duration time when all the air compressors of the braking air system are not started, namely the gas use time in a gas storage tank.
Disclosure of Invention
The present invention has been made in view of the above-described problems.
Therefore, the technical problems solved by the invention are as follows: the existing online calculation method of the air leakage amount has the problems that the air leakage amount change of the braking air system cannot be accurately judged due to the interference of the change of the start-stop frequency of the machine set, and how to monitor the air leakage condition of the braking system in real time.
In order to solve the technical problems, the invention provides the following technical scheme: an online calculation method for the air leakage of a gas system for hydropower station braking comprises the steps of calculating the cavity volume when a mechanical braking device of a single unit is put in and out, judging the running state of an air compressor of the gas system for braking based on the cavity volume, and determining the starting condition of an air leakage calculation flow; calculating the starting interval time of the air compressor and the compressed air variable quantity of an air storage tank of a braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank; and monitoring pressure change, and calculating the air leakage of the braking air system by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of all the units.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: calculating the cavity volume of the mechanical braking device of the single unit when the mechanical braking device is put into and out of the system comprises reflecting the relation with dynamic change in the braking process based on a fluid dynamic model, and simulating the flow and pressure change of air in the system by using a Navier-Stokes equation, wherein a calculation formula is expressed as follows:
；
；
；
wherein the pressure gradient is calculated by deriving the pressure distribution in the system Squaring the calculated pressure gradient along the length of the systemIntegrating to obtain internal integral result, and measuring the internal integral result along the cross-sectional areaIntegrating to obtain the volume of the cavity during the injection, and calculating the pressure along the length direction of the systemWith reference pressureTo obtain pressure difference and perform exponential operation along the length of the systemIntegrating to obtain the internal integral result and the internal integral result along the cross-sectional areaIntegrating to obtain the cavity volume when exiting,AndReflects the air volume requirement of a mechanical braking device of a single unit under different states, integrates the two volumes, reflects the total air requirement of the system in one complete operation process,、The volume of the cavity when the mechanical brake device of a single unit is put in and withdrawn respectively,In order to be able to take the total air demand,AndFor the range of cross-sectional area variation upon the brake device being thrown in and withdrawn,For the length of the braking system,For a pressure distribution along the length of the brake system,As a positional variable along the length of the brake system,AndParameters are adjusted for the system, for simulating the nonlinear characteristics of the compressed air behaviour,AndIs a constant that is adjusted according to the characteristics of the system.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the judging of the operation state of the air compressor of the brake air system and the starting condition of the air leakage calculation flow comprise that the operation state of the air compressor of the brake air system is reflected through a nonlinear model based on the calculated cavity volume result by combining the environmental parameters and the system load, and the operation state is expressed as follows:
；
；
wherein, the state function of each air compressor is weighted and summed and passed through the weight coefficient The air compressor is regulated to be in a dimensionless form, the intermediate value regulated by an exponential function ranges from 0 to 1, the possibility of starting the air compressors is represented, the final running state of the air compressors is judged by a step function, if at least one air compressor in the system needs to run, 1 is output, otherwise, 0 is output,Is the firstThe status function of the individual air compressors, if the cavity volume becomes large, requires more air volume to fill, the air compressors are started more frequently to maintain system pressure,AndThe running state and the environmental parameters of the air compressor are respectively,、、、Is a weight coefficient used for adjusting the influence of different factors on the state of the air compressor,To adjust parameters, the state of each air compressor to the total system is expressedIs used for the degree of contribution of (a),Is a system sensitivity parameter for adjusting the environment parameter and the air compressor state to the total state of the systemIs used for controlling the influence of the force,Is a step function and is used for determining whether the system is in an operating state according to the operating states of all the air compressors,When the air compressor is started,When the air compressor is not started, under the condition that the air compressor is not in operation, starting an air leakage calculation flow according to the opening state of the blowdown electromagnetic valve, wherein the air leakage calculation flow is expressed as follows:
；
wherein, For the state function of each blowdown solenoid valve, if the cavity volume becomes larger, the air demand increases, the opening frequency and duration of the solenoid valve increase, reflecting the system air leakage condition,、、The opening states of the electromagnetic valves, the influencing factors and the pressure change of the system are respectively,The weight parameter is used for representing the contribution of each blowdown solenoid valve to the overall judgment,For processing functions, for integrating information of all solenoid valves and generating a comprehensive judgment index,Is a threshold value for judging whether the condition for starting the calculation of the air leakage is satisfied,When the method is used, the calculation flow of the air leakage is started,And when the air leakage calculation flow is not started.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the calculated starting interval duration of the air compressor and the compressed air variable quantity of the air storage tank of the braking air system comprise a starting time interval and a compressed air variable quantity, and the starting interval duration of the air compressor is expressed as follows:
；
Wherein, calculate AndThe natural logarithm is taken as a comparison value, the air leakage in unit time of all air leakage paths is calculated and summarized, the air leakage coefficient is multiplied by the total air leakage in unit time, compared with the pressure ratio, the time interval between the starting and the stopping of the air compressor is obtained,As the air leakage amount of the air leakage path,AndThe pressure when the air compressor starts and stops respectively,The leakage coefficient is the leakage rate in each cube，For the time span of the air leakage process, through an ideal air state equation and combining a temperature correction factor and an actual air compression factor, the variation of compressed air of an air storage tank of the air system for braking is expressed as:
；
；
Wherein, the mole number of the initial state and the mole number of the final state are calculated, the mole number variation is calculated, the temperature correction treatment is carried out, the variation of the compressed air of the air storage tank is obtained, AndThe pressure in the reservoir at the beginning and end of the time period respectively,AndThe volume within the reservoir at the beginning and end of the time period respectively,AndAbsolute temperatures at the beginning and end of the time period respectively,AndAs a result of the gas compression factor,Is a gas constant, in joules per mole per kelvin,Is a temperature correction function for correcting the influence of temperature change on the change of gas mole number,Is a correction coefficient.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the method comprises the steps of collecting the input and the exit states of each unit mechanical braking device in a calculation period, multiplying the accumulated input and the exit time by the air consumption rate respectively when the air consumption of each unit is calculated, determining the air consumption rate according to the air consumption of the mechanical braking device in different states, adding the air consumption rate to obtain the total air consumption of each unit in the whole calculation period, obtaining the air consumption of a system in a time period based on the compressed air change of an air storage tank and the starting interval time of an air compressor, calculating the air consumption of each unit and the air consumption of the air storage tank in the starting interval of the air compressor, and obtaining the total air consumption of the system, wherein the total air consumption is expressed as:
；
wherein, For the total air consumption of all the mechanical braking devices of the machine set,AndRespectively the firstThe air consumption rate of the mechanical brake device of the unit in the input state and the exit state,AndRespectively the firstThe accumulated input and exit time of the mechanical brake device of each unit in the calculation period.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the monitoring of pressure changes comprises calculating average relative pressure change quantity, monitoring the pressure change of a brake gas system in real time, recording the current pressure of each time period, calculating the expected pressure of each time period according to the compressed air change quantity of a gas storage tank, the starting interval time of an air compressor and the mechanical brake gas quantity of a machine set, calculating the relative difference value between the current monitored pressure and the expected pressure of each time period, taking the average value of the relative pressure change quantity of all time periods, and obtaining the average relative pressure change quantity, wherein the average relative pressure change quantity is expressed as:
；
；
；
；
wherein, For the average relative pressure change monitored,Is the firstThe pressure is currently monitored for a period of time,Is the firstThe desired pressure for the respective time period,In order to obtain the initial number of moles of gas,AndThe initial pressure and the initial volume are respectively,As a result of the initial temperature being set,Is the firstThe total number of moles of gas for each time period,Is the firstThe variation of the compressed air in the air storage tank in each time period,Is the firstThe total air consumption of all the mechanical braking devices of the machine set in each time period,AndRespectively the firstTemperature and volume for each time period.
As a preferable scheme of the online calculation method for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the method for calculating the air leakage of the braking air system comprises the steps of calculating total air leakage, calculating the change of the mole number of air in time periods according to an air state equation by utilizing pressure, volume and temperature data, calculating the total air leakage of the whole system by calculating the difference between the initial pressure and the final pressure of each time period, calculating the sum of the net change of the mole number of air obtained by the difference between the change of the mole number of air in an air storage tank and the air consumption of mechanical braking in each time period, calculating the sum of the change of the mole number of air after temperature correction in each time period, and comprehensively calculating the total air leakage of the whole system, wherein the total air leakage is expressed as follows:
；
；
；
wherein, Is the firstThe air consumption of mechanical braking of the unit in each time period,AndRespectively the firstAnd (d)The number of moles of gas in each time period varies,AndRespectively the firstThe initial and end pressures of the respective time periods,AndRespectively the firstAnd (3) generating virtual measuring points according to the initial and ending pressures of the time periods, storing data into a bin, and automatically alarming when the air leakage exceeds a threshold value.
The invention also aims to provide an online calculation system for the air leakage of the hydraulic power station braking air system, which can calculate and judge the key state in the braking air system through a state judging module, and solves the problems that the system state cannot be accurately mastered in real time at present, and the air leakage problem is difficult to discover and treat in time.
As a preferable scheme of the online calculation system for the air leakage of the hydropower station braking air system, the invention comprises the following steps: the system comprises a state judging module, a collecting state module and an air leakage calculating module; the state judging module is used for calculating the cavity volume when the mechanical brake device of the single unit is put in and out, judging the running state of the air compressor of the brake air system based on the cavity volume, and determining the starting condition of the air leakage calculating flow; the acquisition state module is used for calculating the starting interval time of the air compressor and the compressed air variable quantity of the air storage tank of the braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank; the air leakage calculation module is used for monitoring pressure change, and calculating the air leakage of the braking air system by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of each unit.
A computer device comprising a memory and a processor, said memory storing a computer program, wherein execution of said computer program by said processor is a step of implementing an on-line calculation method of the air leakage of a hydropower station braking air system.
A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor realizes the steps of a method for online calculation of the air leakage of a hydropower station brake air system.
The invention has the beneficial effects that: the online calculation method for the air leakage of the hydropower station braking air system provided by the invention realizes online calculation of the air leakage, knows the health degree and the change trend of the braking air system in real time, obviously improves the efficiency of equipment state evaluation and state maintenance, ensures the accuracy of air leakage calculation, enables the system to generate a virtual measuring point according to real-time data, feeds back the system state in time, automatically alarms when the air leakage exceeds a preset threshold value, timely informs maintenance personnel to take corresponding measures, and enhances the accuracy and timeliness of equipment state evaluation.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without the need of creative efforts for a person of ordinary skill in the art.
Fig. 1 is an overall flowchart of an online calculation method for air leakage of a hydropower station braking air system according to a first embodiment of the present invention.
Fig. 2 is an overall block diagram of an online calculation system for air leakage of a hydropower station braking air system according to a third embodiment of the invention.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1
Referring to fig. 1, for an embodiment of the present invention, there is provided an online calculation method for air leakage of a gas system for hydropower station braking, including:
S1: and calculating the cavity volume when the mechanical brake device of the single unit is put into and withdrawn from, judging the running state of the air compressor of the brake air system based on the cavity volume, and determining the starting condition of the air leakage calculation flow.
Further, calculating the cavity volume as the unit mechanical brake is thrown in and withdrawn includes reflecting the relationship with dynamic changes during braking based on a fluid dynamic model.
It should be noted that the Navier-Stokes equation was used to simulate the flow and pressure changes of air in the system, and the calculation formula was expressed as:
；
；
；
wherein the pressure gradient is calculated by deriving the pressure distribution in the system Squaring the calculated pressure gradient along the length of the systemIntegrating to obtain internal integral result, and measuring the internal integral result along the cross-sectional areaIntegrating to obtain the volume of the cavity during the injection, and calculating the pressure along the length direction of the systemWith reference pressureTo obtain pressure difference and perform exponential operation along the length of the systemIntegrating to obtain the internal integral result and the internal integral result along the cross-sectional areaIntegrating to obtain the cavity volume when exiting,AndReflects the air volume requirement of a mechanical braking device of a single unit under different states, integrates the two volumes, reflects the total air requirement of the system in one complete operation process,、The volume of the cavity when the mechanical brake device of a single unit is put in and withdrawn respectively,In order to be able to take the total air demand,AndFor the range of cross-sectional area variation upon the brake device being thrown in and withdrawn,For the length of the braking system,For a pressure distribution along the length of the brake system,As a positional variable along the length of the brake system,AndParameters are adjusted for the system, for simulating the nonlinear characteristics of the compressed air behaviour,AndIs a constant that is adjusted according to the characteristics of the system.
Further, judging the operation state of the air compressor of the brake air system and the starting condition of the air leakage calculation flow comprises the operation state of the air compressor of the brake air system.
It should be noted that, based on the calculated cavity volume result, in combination with the environmental parameter and the system load, the operation state is reflected by the nonlinear model, expressed as:
；
；
wherein, the state function of each air compressor is weighted and summed and passed through the weight coefficient The air compressor is regulated to be in a dimensionless form, the intermediate value regulated by an exponential function ranges from 0 to 1, the possibility of starting the air compressors is represented, the final running state of the air compressors is judged by a step function, if at least one air compressor in the system needs to run, 1 is output, otherwise, 0 is output,Is the firstThe status function of the individual air compressors, if the cavity volume becomes large, requires more air volume to fill, the air compressors are started more frequently to maintain system pressure,AndThe running state and the environmental parameters of the air compressor are respectively,、、、Is a weight coefficient used for adjusting the influence of different factors on the state of the air compressor,To adjust parameters, the state of each air compressor to the total system is expressedIs used for the degree of contribution of (a),Is a system sensitivity parameter for adjusting the environment parameter and the air compressor state to the total state of the systemIs used for controlling the influence of the force,Is a step function and is used for determining whether the system is in an operating state according to the operating states of all the air compressors,When the air compressor is started,When the air compressor is not started, under the condition that the air compressor is not in operation, starting an air leakage calculation flow according to the opening state of the blowdown electromagnetic valve, wherein the air leakage calculation flow is expressed as follows:
；
wherein, For the state function of each blowdown solenoid valve, if the cavity volume becomes larger, the air demand increases, the opening frequency and duration of the solenoid valve increase, reflecting the system air leakage condition,、、The opening states of the electromagnetic valves, the influencing factors and the pressure change of the system are respectively,The weight parameter is used for representing the contribution of each blowdown solenoid valve to the overall judgment,For processing functions, for integrating information of all solenoid valves and generating a comprehensive judgment index,Is a threshold value for judging whether the condition for starting the calculation of the air leakage is satisfied,When the method is used, the calculation flow of the air leakage is started,And when the air leakage calculation flow is not started.
S2: and calculating the starting interval time of the air compressor and the compressed air variable quantity of the air storage tank of the braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank.
Further, calculating the starting interval time of the air compressor and the compressed air variation of the air storage tank of the air system for braking comprises starting time interval and compressed air variation.
It should be noted that, the duration of the start interval of the air compressor is expressed as:
；
Wherein, calculate AndThe natural logarithm is taken as a comparison value, the air leakage in unit time of all air leakage paths is calculated and summarized, the air leakage coefficient is multiplied by the total air leakage in unit time, compared with the pressure ratio, the time interval between the starting and the stopping of the air compressor is obtained,As the air leakage amount of the air leakage path,AndThe pressure when the air compressor starts and stops respectively,The leakage coefficient is the leakage rate in each cube，For the time span of the air leakage process, through an ideal air state equation and combining a temperature correction factor and an actual air compression factor, the variation of compressed air of an air storage tank of the air system for braking is expressed as:
；
；
Wherein, the mole number of the initial state and the mole number of the final state are calculated, the mole number variation is calculated, the temperature correction treatment is carried out, the variation of the compressed air of the air storage tank is obtained, AndThe pressure in the reservoir at the beginning and end of the time period respectively,AndThe volume within the reservoir at the beginning and end of the time period respectively,AndAbsolute temperatures at the beginning and end of the time period respectively,AndAs a result of the gas compression factor,Is a gas constant, in joules per mole per kelvin,Is a temperature correction function for correcting the influence of temperature change on the change of gas mole number,Is a correction coefficient.
Further, calculating the total air consumption includes collecting the input and the output states of each unit mechanical brake device in a calculation period.
When the air consumption of each unit is calculated, the accumulated input time and the accumulated exit time are multiplied by the air consumption rate respectively, the air consumption rate is determined according to the air consumption of the mechanical braking device in different states, the air consumption rate is added to obtain the total air consumption of each unit in the whole calculation period, the air consumption of the system in the time period is obtained based on the compressed air change quantity of the air storage tank and the starting interval time of the air compressor, the air consumption of each unit and the air consumption of the air storage tank in the starting interval of the air compressor are calculated to obtain the total air consumption of the system, and the total air consumption of the system is expressed as:
；
wherein, For the total air consumption of all the mechanical braking devices of the machine set,AndRespectively the firstThe air consumption rate of the mechanical brake device of the unit in the input state and the exit state,AndRespectively the firstThe accumulated input and exit time of the mechanical brake device of each unit in the calculation period.
S3: and monitoring pressure change, and calculating the air leakage of the braking air system by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of all the units.
Still further, monitoring the pressure change includes calculating an average relative pressure change amount.
It should be noted that, the pressure change of the brake gas system is monitored in real time, the current pressure of each time period is recorded, the expected pressure of each time period is calculated according to the compressed air change quantity of the gas storage tank, the starting interval time of the air compressor and the mechanical brake gas consumption of the machine set, the relative difference value between the current monitored pressure and the expected pressure is calculated for each time period, the average value of the relative pressure change quantity of all time periods is taken, and the average relative pressure change quantity is obtained, and is expressed as:
；
；
；
；
wherein, For the average relative pressure change monitored,Is the firstThe pressure is currently monitored for a period of time,Is the firstThe desired pressure for the respective time period,In order to obtain the initial number of moles of gas,AndThe initial pressure and the initial volume are respectively,As a result of the initial temperature being set,Is the firstThe total number of moles of gas for each time period,Is the firstThe variation of the compressed air in the air storage tank in each time period,Is the firstThe total air consumption of all the mechanical braking devices of the machine set in each time period,AndRespectively the firstTemperature and volume for each time period.
Further, calculating the air leakage of the brake air system includes calculating a total air leakage.
It should be noted that, in each time zone, the change of the number of moles of gas in the time zone is calculated by using the pressure, volume and temperature data according to the gas state equation, the difference between the initial and end pressures of each time zone is calculated, the sum of the net change amounts of the number of moles of gas obtained by the difference between the change of the number of moles of gas in the gas tank and the amount of air used for mechanical braking in each time zone is calculated, the sum of the change amounts of the number of moles of gas after temperature correction in each time zone is calculated, and the total air leakage of the whole system is comprehensively calculated, expressed as:
；
；
；
wherein, Is the firstThe air consumption of mechanical braking of the unit in each time period,AndRespectively the firstAnd (d)The number of moles of gas in each time period varies,AndRespectively the firstThe initial and end pressures of the respective time periods,AndRespectively the firstAnd (3) generating virtual measuring points according to the initial and ending pressures of the time periods, storing data into a bin, and automatically alarming when the air leakage exceeds a threshold value.
Example 2
In order to verify the beneficial effects of the invention, the invention provides an online calculation method for the air leakage of the hydropower station braking air system, and scientific demonstration is carried out through economic benefit calculation and simulation experiments.
The method comprises the steps of installing necessary monitoring equipment in a hydropower station, including a pressure sensor, a temperature sensor, a state detection device of an electromagnetic valve and the like, and a data processing unit matched with the method, ensuring that all monitoring equipment works normally, initializing the data processing unit, setting relevant parameters of air leakage calculation and an air leakage alarm threshold, collecting key parameters such as the running state of each air compressor, the pressure value of an air storage tank, the throwing and retreating state of a braking device and the like in real time, simultaneously carrying out traditional manual inspection, recording inspection time and found air leakage points, automatically calculating the air leakage in each monitoring period, comparing the air leakage with the result of the manual inspection, verifying the accuracy of calculation, analyzing the health state of a braking air system, evaluating the efficiency and accuracy of equipment state evaluation, comparing the air leakage detection time of the method with the traditional manual inspection and historical data comparison method in real time, counting and analyzing the performance of the two methods in terms of state evaluation efficiency and accuracy, and evaluating the air leakage difference of the two methods in time response to the air leakage detection method.
As shown in Table 1, the online computing capability of the invention is obviously improved, the real-time monitoring and the real-time assessment of the air leakage condition can be realized, the time for the equipment state assessment is obviously reduced from 12 hours to 0.5 hour, meanwhile, the accuracy of the air leakage calculation is obviously improved, the error rate is reduced from 15% to below 5%, the accuracy of the calculation result is ensured, and in terms of timeliness, the invention can give an alarm within 1 hour after the air leakage is detected, and compared with the 24-hour feedback period in the prior art, the invention greatly accelerates the discovery and processing speed of the problem, and improves the maintenance efficiency and the safety of the equipment operation.
Table 1 experiment comparison table
Example 3
Referring to fig. 2, for an embodiment of the present invention, there is provided an online calculation system for air leakage of a gas system for hydropower station braking, including: the state judging module is used for collecting the state module and the air leakage calculating module.
The state judging module is used for calculating the cavity volume when the mechanical braking device of the single unit is put in and out and judging the running state of the air compressor of the braking air system and the starting condition of the air leakage calculation flow; the acquisition state module is used for calculating the starting interval time of the air compressor and the compressed air variation of the air storage tank of the braking air system, and acquiring the switching state of the mechanical braking devices of each unit associated with the braking air system; the air leakage calculation module is used for obtaining the input times of the mechanical braking device of the unit and calculating the air consumption of the mechanical braking of the unit and the air leakage of the braking air consumption system.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method of the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium may even be paper or other suitable medium upon which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like. It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been 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 may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been 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 may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered in the scope of the claims of the present invention.
Claims (10)
1. An online calculation method for air leakage of a hydropower station braking air system is characterized by comprising the following steps:
calculating the cavity volume when the mechanical brake device of a single unit is put into and withdrawn from, judging the running state of the air compressor of the brake air system based on the cavity volume, and determining the starting condition of an air leakage calculation flow;
Calculating the starting interval time of the air compressor and the compressed air variable quantity of an air storage tank of a braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank;
And monitoring pressure change, and calculating the air leakage of the braking air system by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of all the units.
2. The on-line calculation method for the air leakage of a hydropower station braking air system as set forth in claim 1, wherein: calculating the cavity volume of the mechanical braking device of the single unit when the mechanical braking device is put into and out of the system comprises reflecting the relation with dynamic change in the braking process based on a fluid dynamic model, and simulating the flow and pressure change of air in the system by using a Navier-Stokes equation, wherein a calculation formula is expressed as follows:
；
；
；
wherein the pressure gradient is calculated by deriving the pressure distribution in the system Squaring the calculated pressure gradient along the length of the systemIntegrating to obtain internal integral result, and measuring the internal integral result along the cross-sectional areaIntegrating to obtain the volume of the cavity during the injection, and calculating the pressure along the length direction of the systemWith reference pressureTo obtain pressure difference and perform exponential operation along the length of the systemIntegrating to obtain the internal integral result and the internal integral result along the cross-sectional areaIntegrating to obtain the cavity volume when exiting,AndReflects the air volume requirement of a mechanical braking device of a single unit under different states, integrates the two volumes, reflects the total air requirement of the system in one complete operation process,、The volume of the cavity when the mechanical brake device of a single unit is put in and withdrawn respectively,In order to be able to take the total air demand,AndFor the range of cross-sectional area variation upon the brake device being thrown in and withdrawn,For the length of the braking system,For a pressure distribution along the length of the brake system,As a positional variable along the length of the brake system,AndParameters are adjusted for the system, for simulating the nonlinear characteristics of the compressed air behaviour,AndIs a constant that is adjusted according to the characteristics of the system.
3. The on-line calculation method for the air leakage of the hydropower station braking air system as set forth in claim 2, wherein: the judging of the operation state of the air compressor of the brake air system and the starting condition of the air leakage calculation flow comprise that the operation state of the air compressor of the brake air system is reflected through a nonlinear model based on the calculated cavity volume result by combining the environmental parameters and the system load, and the operation state is expressed as follows:
；
；
wherein, the state function of each air compressor is weighted and summed and passed through the weight coefficient The air compressor is regulated to be in a dimensionless form, the intermediate value regulated by an exponential function ranges from 0 to 1, the possibility of starting the air compressors is represented, the final running state of the air compressors is judged by a step function, if at least one air compressor in the system needs to run, 1 is output, otherwise, 0 is output,Is the firstThe status function of the individual air compressors, if the cavity volume becomes large, requires more air volume to fill, the air compressors are started more frequently to maintain system pressure,AndThe running state and the environmental parameters of the air compressor are respectively,、、、Is a weight coefficient used for adjusting the influence of different factors on the state of the air compressor,To adjust parameters, the state of each air compressor to the total system is expressedIs used for the degree of contribution of (a),Is a system sensitivity parameter for adjusting the environment parameter and the air compressor state to the total state of the systemIs used for controlling the influence of the force,Is a step function and is used for determining whether the system is in an operating state according to the operating states of all the air compressors,When the air compressor is started,When the air compressor is not started, under the condition that the air compressor is not in operation, starting an air leakage calculation flow according to the opening state of the blowdown electromagnetic valve, wherein the air leakage calculation flow is expressed as follows:
；
wherein, For the state function of each blowdown solenoid valve, if the cavity volume becomes larger, the air demand increases, the opening frequency and duration of the solenoid valve increase, reflecting the system air leakage condition,、、The opening states of the electromagnetic valves, the influencing factors and the pressure change of the system are respectively,The weight parameter is used for representing the contribution of each blowdown solenoid valve to the overall judgment,For processing functions, for integrating information of all solenoid valves and generating a comprehensive judgment index,Is a threshold value for judging whether the condition for starting the calculation of the air leakage is satisfied,When the method is used, the calculation flow of the air leakage is started,And when the air leakage calculation flow is not started.
4. The on-line calculation method for the air leakage of a hydropower station braking air system as set forth in claim 3, wherein: the calculated starting interval duration of the air compressor and the compressed air variable quantity of the air storage tank of the braking air system comprise a starting time interval and a compressed air variable quantity, and the starting interval duration of the air compressor is expressed as follows:
；
Wherein, calculate AndThe natural logarithm is taken as a comparison value, the air leakage in unit time of all air leakage paths is calculated and summarized, the air leakage coefficient is multiplied by the total air leakage in unit time, compared with the pressure ratio, the time interval between the starting and the stopping of the air compressor is obtained,As the air leakage amount of the air leakage path,AndThe pressure when the air compressor starts and stops respectively,The leakage coefficient is the leakage rate in each cube，For the time span of the air leakage process, through an ideal air state equation and combining a temperature correction factor and an actual air compression factor, the variation of compressed air of an air storage tank of the air system for braking is expressed as:
；
；
Wherein, the mole number of the initial state and the mole number of the final state are calculated, the mole number variation is calculated, the temperature correction treatment is carried out, the variation of the compressed air of the air storage tank is obtained, AndThe pressure in the reservoir at the beginning and end of the time period respectively,AndThe volume within the reservoir at the beginning and end of the time period respectively,AndAbsolute temperatures at the beginning and end of the time period respectively,AndAs a result of the gas compression factor,Is a gas constant, in joules per mole per kelvin,Is a temperature correction function for correcting the influence of temperature change on the change of gas mole number,Is a correction coefficient.
5. The on-line calculation method for the air leakage of the hydropower station braking air system as set forth in claim 4, wherein: the method comprises the steps of collecting the input and the exit states of each unit mechanical braking device in a calculation period, multiplying the accumulated input and the exit time by the air consumption rate respectively when the air consumption of each unit is calculated, determining the air consumption rate according to the air consumption of the mechanical braking device in different states, adding the air consumption rate to obtain the total air consumption of each unit in the whole calculation period, obtaining the air consumption of a system in a time period based on the compressed air change of an air storage tank and the starting interval time of an air compressor, calculating the air consumption of each unit and the air consumption of the air storage tank in the starting interval of the air compressor, and obtaining the total air consumption of the system, wherein the total air consumption is expressed as:
；
wherein, For the total air consumption of all the mechanical braking devices of the machine set,AndRespectively the firstThe air consumption rate of the mechanical brake device of the unit in the input state and the exit state,AndRespectively the firstThe accumulated input and exit time of the mechanical brake device of each unit in the calculation period.
6. The on-line calculation method for the air leakage of the hydropower station braking air system as set forth in claim 5, wherein: the monitoring of pressure changes comprises calculating average relative pressure change quantity, monitoring the pressure change of a brake gas system in real time, recording the current pressure of each time period, calculating the expected pressure of each time period according to the compressed air change quantity of a gas storage tank, the starting interval time of an air compressor and the mechanical brake gas quantity of a machine set, calculating the relative difference value between the current monitored pressure and the expected pressure of each time period, taking the average value of the relative pressure change quantity of all time periods, and obtaining the average relative pressure change quantity, wherein the average relative pressure change quantity is expressed as:
；
；
；
；
wherein, For the average relative pressure change monitored,Is the firstThe pressure is currently monitored for a period of time,Is the firstThe desired pressure for the respective time period,In order to obtain the initial number of moles of gas,AndThe initial pressure and the initial volume are respectively,As a result of the initial temperature being set,Is the firstThe total number of moles of gas for each time period,Is the firstThe variation of the compressed air in the air storage tank in each time period,Is the firstThe total air consumption of all the mechanical braking devices of the machine set in each time period,AndRespectively the firstTemperature and volume for each time period.
7. The on-line calculation method for the air leakage of the hydropower station braking air system as set forth in claim 6, wherein: the method for calculating the air leakage of the braking air system comprises the steps of calculating total air leakage, calculating the change of the mole number of air in time periods according to an air state equation by utilizing pressure, volume and temperature data, calculating the total air leakage of the whole system by calculating the difference between the initial pressure and the final pressure of each time period, calculating the sum of the net change of the mole number of air obtained by the difference between the change of the mole number of air in an air storage tank and the air consumption of mechanical braking in each time period, calculating the sum of the change of the mole number of air after temperature correction in each time period, and comprehensively calculating the total air leakage of the whole system, wherein the total air leakage is expressed as follows:
；
；
；
wherein, Is the firstThe air consumption of mechanical braking of the unit in each time period,AndRespectively the firstAnd (d)The number of moles of gas in each time period varies,AndRespectively the firstThe initial and end pressures of the respective time periods,AndRespectively the firstAnd (3) generating virtual measuring points according to the initial and ending pressures of the time periods, storing data into a bin, and automatically alarming when the air leakage exceeds a threshold value.
8. A system adopting the hydropower station braking gas leakage online calculation method according to any one of claims 1-7, which is characterized in that: the system comprises a state judging module, a collecting state module and an air leakage calculating module;
the state judging module is used for calculating the cavity volume when the mechanical brake device of the single unit is put in and out, judging the running state of the air compressor of the brake air system based on the cavity volume, and determining the starting condition of the air leakage calculating flow;
the acquisition state module is used for calculating the starting interval time of the air compressor and the compressed air variable quantity of the air storage tank of the braking air system, and calculating the mechanical braking air consumption of the unit by combining the starting interval of the air compressor and the compressed air variable quantity of the air storage tank;
The air leakage calculation module is used for monitoring pressure change, and calculating the air leakage of the braking air system by calculating the difference value between the expected pressure and the current pressure in each time period and combining the on-off state and the air consumption of the mechanical braking devices of each unit.
9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, performs the steps of the hydropower station braking gas system gas leakage online calculation method according to any one of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the hydropower station braking gas system gas leakage online calculation method according to any one of claims 1 to 7.
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