A control method for a hydraulic dynamometer of the impeller type

Abstract

This invention relates to the field of prime mover calibration, specifically to a control method for a turbine-type hydraulic dynamometer, comprising the following steps: obtaining the optimal opening degree of the inlet valve for all speed segments through segmented speed trial adjustment; obtaining the specific operating condition speed value, speed adjustment range, and automatic adjustment closing value of the drain valve for each operating condition; performing weighted judgment based on the speed monitoring sequence; calculating the linear fitting degree as a correction coefficient, and obtaining the speed deviation and valve position correction amount. This invention matches a dedicated speed adjustment range and initial adjustment value of the drain valve for each preset operating condition, eliminating the need for blind trial and error in the gradient adjustment of the drain valve, enabling rapid adaptation to the operating condition switching requirements of the prime mover, shortening the convergence time of speed control, and improving the dynamometer's response speed to operating condition switching.

Description

Technical Field

[0001] This invention relates to the field of prime mover verification, and specifically to a control method for a turbine-type hydraulic dynamometer. Background Technology

[0002] The impeller-type hydraulic dynamometer is a commonly used device for power testing of power machinery. Its core principle is to absorb and measure the output power of the prime mover under test through water resistance. It is suitable for performance testing of power machinery such as internal combustion engines, electric motors, and hydraulic motors, covering scenarios including R&D, production quality inspection, and maintenance calibration. It meets the continuous testing needs of power machinery from low load to full load, and is particularly suitable for operating conditions requiring stable loads and rapid adjustments. With its advantages of simple structure, moderate cost, and convenient maintenance, it is widely used in power test benches in industries such as automobiles, ships, and construction machinery.

[0003] Impeller-type hydraulic dynamometers are mainly divided into two categories: remote control and automatic control, adapting to different testing scenarios. Remote control: The water flow is adjusted by remotely controlling the opening of the inlet and outlet valves, directly changing the water level inside the casing and thus adjusting the resistance load. The inlet and outlet valves operate under single-loop closed-loop automatic control according to a given valve position, while open-loop control is implemented for the torque parameter of the hydraulic dynamometer. Automatic control: The prime mover of the tested machine maintains the target speed. The hydraulic dynamometer achieves closed-loop feedback control with torque as the control target. It integrates force and speed sensors to collect test data in real time. After comparing the torque value with the set value, it automatically controls the inlet and outlet valve positions to control the water flow, ensuring load stability and meeting high-precision testing requirements.

[0004] However, the existing remote control methods for impeller-type hydraulic dynamometers mostly adopt simple command mapping control, which has the following technical pain points: In the remote operation mode, the valve positions of the inlet and outlet valves of the hydraulic dynamometer are fixed, resulting in slow convergence and long time during the speed control of the prime mover; even after stabilization, the speed fluctuation is still large. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing a control method for a turbine-type hydraulic dynamometer.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A control method for a turbine-type hydraulic dynamometer, comprising the following steps: S1. Based on multiple trial adjustments and multi-index monitoring, the opening degree of the impeller hydraulic dynamometer, the opening degree of the drain valve, and the optimal linear adjustment range of the drain valve are determined. Then, the optimal opening degree of the inlet valve in all speed ranges is obtained by segmented trial adjustments of the rotation speed and entered into the database to form the inlet valve operation library. S2. Based on the inlet valve operation library, retrieve the optimal opening value of the inlet valve in the impeller-type hydraulic dynamometer, perform gradient adjustment of the opening, obtain the inlet valve opening that meets the simulated operating index, and lock it as the fixed valve position of the inlet valve. Under the fixed valve position of the inlet valve of the impeller-type hydraulic dynamometer, according to the preset operating point of the prime mover under test, obtain the specific operating speed value, speed adjustment range and automatic adjustment closing value of the drain valve for each operating condition. S3. Perform operating condition switching control on the tested original machine, set the remote control given valve position value of the drain valve, and perform remote control open-loop control based on the drain valve to gradually adjust the opening of the drain valve in a gradient manner, keep the water inlet valve fixed in a fixed position, and collect data from the speed sensor to form a real-time speed monitoring sequence, and make weighted judgments based on the speed monitoring sequence. S4. Group the speed values ​​under different specific operating conditions, and obtain the speed deviation value and the corresponding drain valve opening adjustment amount by changing the actual speed of the prime mover under each specific operating condition speed value. Form a calibration dataset of speed values ​​under each specific operating condition, fit a linear trend line, calculate the linear fitting degree as the correction coefficient, and obtain the speed deviation and valve position correction amount.

[0007] In a preferred embodiment, S1 connects the impeller-type hydraulic dynamometer with the prime mover under test, switches to the remote control operation mode of the impeller-type hydraulic dynamometer, turns on the water supply system of the test bench, and monitors the water supply pressure and flow data in real time through the pressure transmitter and electromagnetic flow meter, and monitors the water ring thickness, load torque and equipment vibration amplitude in real time through the built-in sensor of the dynamometer. The inlet valve was manually adjusted step by step to increase the opening at a fixed gradient. At each opening, the vibration amplitude of the equipment and the actual water supply were recorded. The linear fit of the inlet valve at the corresponding opening was calculated, and the opening range that met the requirements of opening, load fluctuation and equipment vibration was selected. The linear fit degree is calculated at each opening degree to obtain the basic range of the opening degree of the drain valve in the whole operating range. The opening degree in the basic range is then subdivided into gradients, and the linear fit degree is calculated point by point. The continuous opening degree interval that meets the linear fit degree requirement, that is, the linear fit degree exceeding 0.95, is selected as the optimal linear adjustment interval of the drain valve.

[0008] In a preferred embodiment, in the remote control operation mode, the full speed range of the prime mover under test is divided into segments of 10 rpm from low to high to cover all working conditions of all loads, and the intermediate speed of each segment is extracted as the representative speed. The opening degree of the inlet valve for each speed range is set as the lower limit of the basic range of the inlet valve opening, and used as the initial opening degree. The opening degree of the inlet valve is gradually increased in a gradient. Real-time monitoring parameters including the water supply pressure of the test bench, water supply flow rate, water ring thickness, load fluctuation coefficient, equipment vibration amplitude, and actual water supply are obtained through a dynamometer until the opening degree is increased to the point that all real-time monitoring data are qualified. The test bench water supply pressure fluctuation is ≤0.02MPa and the water supply flow fluctuation is ≤5L / min. When the vibration amplitude and / or water supply flow are unqualified, the gradient increase is stopped and the opening degree at this point is taken as the optimal opening degree value of the inlet valve for the corresponding speed range. After the optimal opening values ​​of the inlet valves for all speed ranges are adjusted, the corresponding optimal opening values ​​of the inlet valves and the corresponding real-time monitoring parameters are entered into the database using the measured prime mover speed as an index, forming an inlet valve operation library covering the entire operating speed range of the prime mover.

[0009] In a preferred embodiment, S2 retrieves the optimal opening value of the inlet valve from the impeller-type hydraulic dynamometer from the inlet valve operation library, adjusts the inlet valve to the optimal opening value, increases the opening of the inlet valve in a 5% gradient, and performs full-condition simulation operation of the prime mover after each gradient increase, and obtains real-time monitoring parameters through the dynamometer. If the parameters of the prime mover are qualified during the simulation operation, and the gradient continues to increase, resulting in unqualified vibration amplitude and / or unqualified water supply flow, the gradient increase and inlet valve adjustment will stop. The control system of the impeller-type hydraulic dynamometer will lock the opening of the inlet valve to the fixed valve position at this time.

[0010] In a preferred embodiment, after locking the opening of the water inlet valve, S2 determines the specific operating speed value corresponding to each operating condition based on the preset operating condition point of the prime mover under test. The preset operating condition points are such as 60rpm, 80rpm, 100rpm, 150rpm, etc., and sets a corresponding speed adjustment range for each specific operating condition speed value. Here, the speed adjustment range refers to the speed control accuracy requirement of the prime mover under test, and the actual requirements are different under different specific implementation conditions. Then, the midpoint of the optimal linear adjustment range of the drain valve is selected as the automatic adjustment value of the drain valve.

[0011] In a preferred embodiment, in the remote control operation mode of the impeller-type hydraulic dynamometer, according to the switching requirements of the prime mover from one working condition to the next working condition, the actual speed of the prime mover falls within the speed adjustment range of the specific working condition speed value, and the real-time monitoring parameters obtained by the dynamometer are qualified, and 10% of the middle value of the speed adjustment range falls within is taken as the remote control given valve position value of the drain valve. The drain valve is remotely controlled in an open-loop manner according to the given valve position value, and the opening of the drain valve is gradually adjusted until the impeller-type hydraulic dynamometer and the prime mover being tested meet the target operating conditions.

[0012] In a preferred embodiment, S3 further includes: The actual rotational speed of the prime mover under test is collected in real time by the speed sensor of the impeller-type hydraulic dynamometer, forming a real-time speed monitoring sequence. If the speed value in the real-time speed monitoring sequence falls within the set speed adjustment range for 30 consecutive seconds, it is determined that the first threshold is met; otherwise, it is not met, and the first weighting judgment is completed. The system detects whether the real-time monitoring parameters obtained by the dynamometer are qualified, and determines that there is no human intervention operation if there is no signal of manual operation of the inlet and outlet valves for 60 seconds. Otherwise, it is not qualified, and the second weighting judgment is completed. If both the first and second weighting criteria are met, the drain valve position is automatically corrected and compensated. If either criterion is not met, the drain valve is kept under remote open-loop control.

[0013] In a preferred embodiment, after triggering the automatic correction and compensation adjustment of the drain valve position, step S4 groups the components according to different specific operating condition speed values. Each group of different specific operating condition speed values ​​is calibrated. During the test, the inlet valve remains in the fixed position of step three, and all real-time collected parameters must be qualified. For all different specific operating condition speed value groups, the actual speed of the prime mover under test is stabilized at the corresponding specific operating condition speed value by manual adjustment. The remote control given valve position value of the drain valve at this time is obtained, which is 10% of the specific operating condition speed value. The actual speed of the prime mover under test is gradually changed. In this application, the change is ±1 rpm each time, and the changed actual speed is always within the speed adjustment range corresponding to the specific operating condition speed value. The gradient adjustment continues until the actual speed of the prime mover under test returns to the corresponding specific operating condition speed value. The drain valve opening adjustment amount corresponding to the speed deviation value at this time is recorded. It should be noted that the speed deviation value is the difference between the changed actual speed and the specific operating condition speed value, and the drain valve opening adjustment amount refers to the difference between the adjusted opening and the initial given valve position value.

[0014] In a preferred embodiment, step S4 collects the speed deviation values ​​and corresponding drain valve opening adjustment amounts corresponding to all different specific operating conditions to form the corresponding calibration dataset. Then, a scatter plot is drawn with the speed deviation value as the abscissa and the drain valve opening adjustment amount as the ordinate. A linear trend line is fitted using the least squares method, and the slope of the obtained linear trend line is used as the initial correction coefficient corresponding to the speed value of the specific operating condition. The linear fitting degree after fitting is calculated. The operation is repeated until the initial correction coefficients corresponding to the speed values ​​of all specific operating conditions are completed.

[0015] In a preferred embodiment, step S4 takes the difference between the actual speed of the prime mover and the speed under a specific operating condition as the speed deviation. A positive result indicates that the actual speed is higher than the target speed, and a negative result indicates that the actual speed is lower than the target speed. The product of the speed deviation and the correction coefficient is used as the valve position correction amount of the drain valve.

[0016] The beneficial effects of this invention are as follows: by monitoring multiple indicators to complete the screening of the optimal linear adjustment range of the drain valve, and then by performing segmented trial adjustments on the prime mover across the entire speed range and constructing an inlet valve operation library covering all working conditions, the determination of the fixed valve position of the inlet valve has a precise working condition basis; at the same time, a dedicated speed adjustment range and initial adjustment value of the drain valve are matched for each preset working condition, so that the gradient adjustment of the drain valve does not need to be blindly tested, and can quickly meet the working condition switching requirements of the prime mover, shortening the convergence time of speed control and improving the response speed of the dynamometer to the working condition switching. A dual weighting judgment mechanism was designed to strictly judge the speed monitoring status and manual intervention, ensuring that automatic correction compensation is triggered only when the operating conditions are stable, avoiding additional fluctuations caused by ineffective correction. At the same time, the correspondence between speed deviation and drain valve opening adjustment was obtained through calibration tests, and the correction coefficient was obtained through linear fitting, realizing precise valve position compensation based on speed deviation. It can correct small speed deviations in the prime mover operation in real time, eliminating the drawback of easy speed fluctuation in the existing fixed valve position mode from the control logic, greatly improving the stability of prime mover speed control, and thus improving the accuracy of dynamometer power testing of prime mover. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention; Figure 2 This is a comparison chart of the rotational speed fluctuations before and after the improvement of the hydraulic dynamometer according to the present invention. Detailed Implementation

[0018] The present invention will now be further described with reference to the accompanying drawings.

[0019] As attached Figure 1-2 As shown, this embodiment provides a control method for a turbine-type hydraulic dynamometer, comprising the following steps: S1. Based on multiple trial adjustments and multi-index monitoring, the opening degree of the impeller hydraulic dynamometer, the opening degree of the drain valve, and the optimal linear adjustment range of the drain valve are determined. Then, the optimal opening degree of the inlet valve in all speed ranges is obtained by segmented trial adjustments of the rotation speed and entered into the database to form the inlet valve operation library. S2. Based on the inlet valve operation library, retrieve the optimal opening value of the inlet valve in the impeller-type hydraulic dynamometer, perform gradient adjustment of the opening, obtain the inlet valve opening that meets the simulated operating index, and lock it as the fixed valve position of the inlet valve. Under the fixed valve position of the inlet valve of the impeller-type hydraulic dynamometer, according to the preset operating point of the prime mover under test, obtain the specific operating speed value, speed adjustment range and automatic adjustment closing value of the drain valve for each operating condition. S3. Perform working condition switching control on the tested original machine, set the remote control given valve position value of the drain valve, and perform remote open-loop control on the drain valve to gradually adjust the opening of the drain valve in a gradient, while keeping the water inlet valve fixed in a fixed position. The data collected by the speed sensor forms a real-time speed monitoring sequence, and the speed monitoring sequence is used for weighted judgment. S4. Group the speed values ​​under different specific operating conditions, and obtain the speed deviation value and the corresponding drain valve opening adjustment amount by changing the actual speed of the prime mover under each specific operating condition speed value. Form a calibration dataset of speed values ​​under each specific operating condition, fit a linear trend line, calculate the linear fit degree as the correction coefficient, and obtain the speed deviation and valve position correction amount.

[0020] S1 connects the impeller-type hydraulic dynamometer with the prime mover under test, switches to the remote control operation mode of the impeller-type hydraulic dynamometer, turns on the water supply system of the test bench, and monitors the water supply pressure and flow data in real time through the pressure transmitter and electromagnetic flow meter, and monitors the water ring thickness, load torque and equipment vibration amplitude in real time through the built-in sensor of the dynamometer. The inlet valve was manually adjusted step by step to increase the opening at a fixed gradient. At each opening, the vibration amplitude of the equipment and the actual water supply were recorded. The linear fit of the inlet valve at the corresponding opening was calculated, and the opening range that met the requirements of opening, load fluctuation and equipment vibration was selected. It should be noted that, in this field, the thickness of the water ring inside the housing is detected in real time by a built-in water ring thickness detection device in the impeller-type hydraulic dynamometer. If the fluctuation range of the water ring thickness is ≤0.5 mm within a continuous 30-second detection cycle, the water ring thickness is considered stable. The load torque is detected in real time by a built-in load torque sensor in the impeller-type hydraulic dynamometer. The deviation between the instantaneous value and the average value of the load torque is the load fluctuation. A load fluctuation of less than or equal to 2% indicates no significant load fluctuation, while a fluctuation greater than 2% indicates the presence of load fluctuation. According to the Class A requirements of the industrial equipment vibration assessment standard, the vibration amplitude is detected by a vibration sensor installed in the dynamometer housing, and the vibration amplitude must be less than or equal to 2.8 mm / s. The water supply flow rate is detected by an electromagnetic flowmeter on the test bench. Under a certain load of the prime mover, the actual water supply of the dynamometer is greater than or equal to the minimum water demand of the dynamometer under that load, and less than or equal to the maximum safe water supply of the dynamometer under that load, to avoid excessive water flow causing equipment vibration. Therefore, it is necessary to screen valves with vibration amplitude ≤ 2.8 mm / s and valve linear fit R.2 ≥0.95, the opening range of the actual water supply within the range of minimum water demand - maximum safe water supply.

[0021] It should be added that, in the specific calculation, the linear correspondence between valve opening and actual flow rate is determined by selecting five or more equally spaced valve opening points, detecting the actual flow rate at each opening point, plotting a scatter plot with opening as the x-axis and actual flow rate as the y-axis, fitting a linear trend line using the least squares method, and calculating the linear fit. In this field, a value greater than 0.95 indicates good valve linearity, while a value less than 0.95 indicates non-linear regulation. The higher the linearity, the better the accuracy of valve regulation. The linear fit degree is calculated at each opening degree to obtain the basic range of the opening degree of the drain valve in the whole operating range. The opening degree in the basic range is then subdivided into gradients, and the linear fit degree is calculated point by point. The continuous opening degree interval that meets the linear fit degree requirement, that is, the linear fit degree exceeding 0.95, is selected as the optimal linear adjustment interval of the drain valve.

[0022] In remote control mode, S1 divides the entire speed range of the prime mover under test into segments of 10 rpm from low to high, covering all load conditions and extracting the intermediate speed of each segment as the representative speed. The opening degree of the inlet valve for each speed range is set as the lower limit of the basic range of the inlet valve opening, and used as the initial opening degree. The opening degree of the inlet valve is gradually increased in a gradient. Real-time monitoring parameters including the water supply pressure of the test bench, water supply flow rate, water ring thickness, load fluctuation coefficient, equipment vibration amplitude, and actual water supply are obtained through a dynamometer until the opening degree is increased to the point that all real-time monitoring data are qualified. The test bench water supply pressure fluctuation is ≤0.02MPa and the water supply flow fluctuation is ≤5L / min. When the vibration amplitude and / or water supply flow are unqualified, the gradient increase is stopped and the opening degree at this point is taken as the optimal opening degree value of the inlet valve for the corresponding speed range. After the optimal opening values ​​of the inlet valves for all speed ranges are adjusted, the corresponding optimal opening values ​​of the inlet valves and the corresponding real-time monitoring parameters are entered into the database using the measured prime mover speed as an index, forming an inlet valve operation library covering the entire operating speed range of the prime mover.

[0023] S2 retrieves the optimal opening value of the inlet valve from the impeller-type hydraulic dynamometer in the inlet valve operation library, adjusts the inlet valve to the optimal opening value, and increases the opening of the inlet valve in a 5% gradient. After each gradient increase, it performs full-condition simulation operation of the prime mover and obtains real-time monitoring parameters through the dynamometer. If the parameters of the prime mover are qualified during the simulation operation, and the gradient continues to increase, resulting in unqualified vibration amplitude and / or unqualified water supply flow, the gradient increase and inlet valve adjustment will stop. The control system of the impeller-type hydraulic dynamometer will lock the opening of the inlet valve to the fixed valve position at this time.

[0024] After locking the water inlet valve opening, S2 determines the specific operating speed value corresponding to each operating condition based on the preset operating condition point of the prime mover under test. The preset operating condition points are such as 60rpm, 80rpm, 100rpm, 150rpm, etc., and sets the corresponding speed adjustment range for each specific operating condition speed value. The speed adjustment range here refers to the speed control accuracy requirement of the prime mover under test, and the actual requirements are different under different specific implementation conditions. Then, the midpoint of the optimal linear adjustment range of the drain valve is selected as the automatic adjustment value of the drain valve.

[0025] In the remote control operation mode of the impeller-type hydraulic dynamometer, according to the switching requirements of the prime mover from one working condition to the next, the actual speed of the prime mover falls within the speed adjustment range of the specific working condition speed value, and the real-time monitoring parameters obtained by the dynamometer are qualified. The middle value of the speed adjustment range that falls within is taken as 10% as the remote control given valve position value of the drain valve. The drain valve is remotely controlled in an open-loop manner according to the given valve position value, and the opening of the drain valve is gradually adjusted until the impeller-type hydraulic dynamometer and the prime mover being tested meet the target operating conditions.

[0026] S3 also includes: The actual rotational speed of the prime mover under test is collected in real time by the speed sensor of the impeller-type hydraulic dynamometer, forming a real-time speed monitoring sequence. If the speed value in the real-time speed monitoring sequence falls within the set speed adjustment range for 30 consecutive seconds, it is determined that the first threshold is met; otherwise, it is not met, and the first weighting judgment is completed. The system detects whether the real-time monitoring parameters obtained by the dynamometer are qualified, and determines that there is no human intervention operation if there is no signal of manual operation of the inlet and outlet valves for 60 seconds. Otherwise, it is not qualified, and the second weighting judgment is completed. If both the first and second weighting criteria are met, the drain valve position is automatically corrected and compensated. If either criterion is not met, the drain valve is kept under remote open-loop control.

[0027] S4 After triggering the automatic correction and compensation adjustment of the drain valve position, the speed is grouped according to different set specific operating conditions. Each group of different specific operating conditions speed values ​​is calibrated. During the test, the inlet valve remains in the fixed valve position of step three. All real-time parameters collected during operation must be qualified. For all different specific operating conditions speed value groups, the actual speed of the prime mover under test is stabilized at the corresponding specific operating condition speed value by manual adjustment. The remote control given valve position value of the drain valve at this time is obtained, which is 10% of the specific operating condition speed value. The actual speed of the prime mover under test is gradually changed. This application changes it by ±1 rpm each time, and the changed actual speed is always within the speed adjustment range corresponding to the specific operating condition speed value. Gradual adjustment is performed until the actual speed of the prime mover under test returns to the corresponding specific operating condition speed value. The drain valve opening adjustment amount corresponding to the speed deviation value at this time is recorded. It should be noted that the speed deviation value is the difference between the changed actual speed and the specific operating condition speed value. The drain valve opening adjustment amount refers to the difference between the adjusted opening and the initial given valve position value.

[0028] S4 collects the speed deviation values ​​and corresponding drain valve opening adjustment values ​​for all different specific operating conditions to form the corresponding calibration dataset. Then, it plots a scatter plot with the speed deviation value on the x-axis and the drain valve opening adjustment value on the y-axis. A linear trend line is fitted using the least squares method. The slope of the obtained linear trend line is used as the initial correction coefficient for the speed value of the specific operating condition, and the linear fit degree is calculated. The operation is repeated until the initial correction coefficients for the speed values ​​of all specific operating conditions are completed.

[0029] S4 takes the difference between the actual speed of the prime mover and the speed under a specific operating condition as the speed deviation. The result is in rpm and is kept to one decimal place. A positive result indicates that the actual speed is higher than the target speed, and a negative result indicates that the actual speed is lower than the target speed. The product of the speed deviation and the correction coefficient is used as the valve position correction amount of the drain valve.

[0030] Furthermore, this application also provides a method for judging speed deviation and valve position correction amount, specifically: multiple specific operating condition speed values ​​are set in ascending order of value, and each specific operating condition speed value is used as the center, combined with its corresponding final speed adjustment range, to divide non-overlapping speed intervals. The upper and lower limits of each interval are the specific operating condition speed value plus and minus the speed adjustment range, respectively; if the actual speed exceeds all the divided intervals, it is determined that there is no corresponding reference speed. Furthermore, the specific speed range to which the current actual speed of the prime mover belongs is determined, and the center value of this range is extracted as the reference speed. The valve position auxiliary amount is equal to the current actual speed of the prime mover minus the reference speed of its range. If the calculated value of the valve position auxiliary quantity is less than the negative speed adjustment range, that is, the actual speed is lower than the target speed by more than the set speed adjustment range, the speed deviation is determined to be an invalid deviation, the value of the valve position auxiliary quantity is set to 0, and it is not included in the subsequent compensation calculation. If the valve position auxiliary quantity is within the effective range, the calculated value is retained as the effective valve position auxiliary quantity.

Claims

1. A control method for a turbine-type hydraulic dynamometer, characterized in that, Includes the following steps: S1. Based on multiple trial adjustments and multi-index monitoring, the opening degree of the impeller hydraulic dynamometer, the opening degree of the drain valve, and the optimal linear adjustment range of the drain valve are determined. Then, the optimal opening degree of the inlet valve in all speed ranges is obtained by segmented trial adjustments of the rotation speed and entered into the database to form the inlet valve operation library. S2. Based on the inlet valve operation library, retrieve the optimal opening value of the inlet valve in the impeller-type hydraulic dynamometer, perform gradient adjustment of the opening, obtain the inlet valve opening that meets the simulated operating index, and lock it as the fixed valve position of the inlet valve. Under the fixed valve position of the inlet valve of the impeller-type hydraulic dynamometer, according to the preset operating point of the prime mover under test, obtain the specific operating speed value, speed adjustment range and automatic adjustment closing value of the drain valve for each operating condition. S3. Perform working condition switching control on the tested original machine, set the remote control given valve position value of the drain valve, and perform remote open-loop control on the drain valve to gradually adjust the opening of the drain valve in a gradient, while keeping the water inlet valve fixed in a fixed position. The data collected by the speed sensor forms a real-time speed monitoring sequence, and the speed monitoring sequence is used for weighted judgment. S4. Group the speed values ​​under different specific operating conditions, and obtain the speed deviation value and the corresponding drain valve opening adjustment amount by changing the actual speed of the prime mover under each specific operating condition speed value. Form a calibration dataset of speed values ​​under each specific operating condition, fit a linear trend line, calculate the linear fit degree as the correction coefficient, and obtain the speed deviation and valve position correction amount.

2. The control method for a turbine-type hydraulic dynamometer according to claim 1, characterized in that, S1 connects the impeller-type hydraulic dynamometer to the prime mover under test, switches to the remote control operation mode of the impeller-type hydraulic dynamometer, turns on the water supply system of the test bench, and monitors the water supply pressure and flow data in real time through the pressure transmitter and electromagnetic flow meter, and monitors the water ring thickness, load torque and equipment vibration amplitude in real time through the built-in sensor of the dynamometer. The inlet valve was manually adjusted step by step to increase the opening at a fixed gradient. At each opening, the vibration amplitude of the equipment and the actual water supply were recorded. The linear fit of the inlet valve at the corresponding opening was calculated, and the opening range that met the requirements of opening, load fluctuation and equipment vibration was selected. The linear fit degree is calculated at each opening degree to obtain the basic range of the opening degree of the drain valve in the whole operating range. The opening degree in the basic range is then subdivided by gradient, and the linear fit degree is calculated point by point. The continuous opening degree interval that meets the linear fit degree requirement is selected as the optimal linear adjustment interval of the drain valve.

3. The control method for a turbine-type hydraulic dynamometer according to claim 2, characterized in that, In the remote control operation mode, S1 divides the entire speed range of the prime mover under test into segments from low to high in fixed units to cover all working conditions of all loads, and extracts the intermediate speed of each segment as the representative speed. The opening degree of the inlet valve for each speed range is set as the lower limit of the basic range of the inlet valve opening, and used as the initial opening degree. The opening degree of the inlet valve is gradually increased in a gradient. Real-time monitoring parameters including water supply pressure, water supply flow, water ring thickness, load fluctuation coefficient, equipment vibration amplitude, and actual water supply are obtained through a dynamometer until the opening degree is increased to the point where all real-time monitoring data are qualified. The gradual increase in gradient is stopped when the vibration amplitude and / or water supply flow are unqualified. The opening degree at this point is taken as the optimal opening degree value of the inlet valve for the corresponding speed range. After the optimal opening values ​​of the inlet valves for all speed ranges are adjusted, the corresponding optimal opening values ​​of the inlet valves and the corresponding real-time monitoring parameters are entered into the database using the measured prime mover speed as an index, forming an inlet valve operation library covering the entire operating speed range of the prime mover.

4. The control method for a turbine-type hydraulic dynamometer according to claim 1, characterized in that, S2 retrieves the optimal opening value of the inlet valve from the impeller-type hydraulic dynamometer in the inlet valve operation library, adjusts the inlet valve to the optimal opening value, and increases the opening of the inlet valve in a 5% gradient. After each gradient increase, the prime mover is simulated under full working conditions, and real-time monitoring parameters are obtained through the dynamometer. When the parameters of the prime mover are monitored in real time during simulation and are within acceptable limits, the gradient continues to increase. If the vibration amplitude is unacceptable and / or the water supply flow is unacceptable, the gradient increase and the adjustment of the inlet valve will stop. The control system of the impeller-type hydraulic dynamometer will lock the opening of the inlet valve to the fixed position of the inlet valve at this time.

5. The control method for a turbine-type hydraulic dynamometer according to claim 4, characterized in that, After locking the opening of the inlet valve, S2 determines the specific operating speed value corresponding to each operating condition based on the preset operating condition point of the prime mover under test, and sets a corresponding speed adjustment range for each specific operating condition speed value. Then, the midpoint of the optimal linear adjustment range of the drain valve is selected as the automatic adjustment value of the drain valve.

6. The control method for a turbine-type hydraulic dynamometer according to claim 1, characterized in that, In the remote control operation mode of the impeller-type hydraulic dynamometer, according to the switching requirements of the prime mover from one working condition to the next working condition, the actual speed of the prime mover falls within the speed adjustment range of the specific working condition speed value, and the real-time monitoring parameters obtained by the dynamometer are qualified. The middle value of the speed adjustment range that falls within is taken as 10% as the remote control given valve position value of the drain valve. The drain valve is remotely controlled in an open-loop manner according to the given valve position value, and the opening of the drain valve is gradually adjusted until the impeller-type hydraulic dynamometer and the prime mover being tested meet the target operating conditions.

7. The control method for a turbine-type hydraulic dynamometer according to claim 6, characterized in that, S3 further includes: The actual rotational speed of the prime mover under test is collected in real time by the speed sensor of the impeller-type hydraulic dynamometer, forming a real-time speed monitoring sequence. If the speed value in the real-time speed monitoring sequence falls within the set speed adjustment range for 30 consecutive seconds, it is determined that the first threshold is met; otherwise, it is not met, and the first weighting judgment is completed. The system detects whether the real-time monitoring parameters obtained by the dynamometer are qualified, and determines that there is no human intervention operation if there is no signal of manual operation of the inlet and outlet valves for 60 seconds. Otherwise, it is not qualified, and the second weighting judgment is completed. If both the first and second weighting criteria are met, the drain valve position is automatically corrected and compensated. If either criterion is not met, the drain valve is kept under remote open-loop control.

8. The control method for a turbine-type hydraulic dynamometer according to claim 1, characterized in that, After triggering the automatic correction and compensation adjustment of the drain valve position, S4 groups the speed values ​​according to different specific operating conditions. Each group of different specific operating condition speed values ​​is calibrated. For all groups of different specific operating condition speed values, the actual speed of the prime mover under test is stabilized at the corresponding specific operating condition speed value by manual adjustment. The remote control given valve position value of the drain valve is obtained at this time. The actual speed of the prime mover under test is gradually changed, and the changed actual speed is always within the speed adjustment range corresponding to the specific operating condition speed value. The gradual adjustment is continued until the actual speed of the prime mover under test returns to the corresponding specific operating condition speed value. The drain valve opening adjustment amount corresponding to the speed deviation value at this time is recorded.

9. A control method for a turbine-type hydraulic dynamometer according to claim 8, characterized in that, S4 collects the speed deviation values ​​and corresponding drain valve opening adjustment amounts corresponding to all different specific operating conditions to form the corresponding calibration dataset. Then, a scatter plot is drawn with the speed deviation value as the abscissa and the drain valve opening adjustment amount as the ordinate. A linear trend line is fitted by the least squares method. The slope of the obtained linear trend line is used as the initial correction coefficient corresponding to the speed value of the specific operating condition, and the linear fit degree is calculated. The operation is repeated until the initial correction coefficients corresponding to the speed values ​​of all specific operating conditions are completed.

10. The control method for a turbine-type hydraulic dynamometer according to claim 1, characterized in that, S4 takes the difference between the actual speed of the prime mover and the speed under a specific operating condition as the speed deviation, and takes the product of the speed deviation and the correction coefficient as the valve position correction amount of the drain valve.

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