How to correct single valve and sequence valve parameters based on DEH valve flow characteristics

Abstract

The present invention relates to a method for correcting single valve and sequence valve parameters according to the DEH valve flow characteristics, which belongs to the technical field of thermal automatic control of thermal power plant. The system is composed of a data collection module, a data processing module, a parameter correction module for each branch high pressure control valve in single valve control mode, and a parameter correction module for each branch high pressure control valve in sequence valve control mode. The present invention provides nonlinear compensation data for the control valve of a steam turbine, and after carrying out the DEH control linear correction, the change in the overall valve position command of the steam turbine after unit load is guaranteed to change linearly corresponding to the generated steam flow rate and unit load, which improves the promptness and stability of unit load control, prevents the occurrence of vibration in unit load control, and has a good promoting effect on improving the control quality of unit AGC and primary frequency modulation, which is of great significance to the safe, stable, economical and reliable operation of thermal power unit.

Description

[Technical field]

[0001] The present invention relates to the technical field of thermal automatic control of thermal power plants, and particularly to a method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics. [Background technology]

[0002] With the proposal of the "carbon peak and carbon neutral" goal, a new type of power system mainly based on wind and solar power generation is being built. Affected by the variability and uncertainty of wind and solar power generation, large-scale new energy grid connection brings many problems, especially the frequency problem. The frequency problems brought about by the grid connection of wind and solar power generation are caused by their respective output characteristics, variability and uncertainty on the one hand, and on the other hand, the lack of rotational inertia and the problem of sag adjustment after adjustment lead to further deterioration of frequency. Thermal power generation units, which are high-quality FM resources, can basically react on the spot in about 30 seconds, and can rely on the larger moment of inertia to ensure a higher FM effect.

[0003] Thermal power generation equipment not only plays a good role as the "ballast" of the new power system, but is also an indispensable part of the current new power system in construction. The valve characteristic curve of the majority of units is extended to the characteristic curve formulated when the turbine is shipped from the factory, and does not consider the unit overhaul to overhaul the valve of the turbine for each power generation enterprise, so the valve stroke is adjusted more or less, the valve flow characteristic changes, no experimental correction of the characteristic curve is made, and the original characteristic curve is still used, so the valve flow characteristic curve used in the DCS does not match the actual valve flow characteristic, and the integrated valve position command of the unit shows a large nonlinearity with the generated steam flow rate and unit load, which has a great impact on the response speed and adjustment effect of the primary FM of the thermal power generation unit. Rediscovering the flow characteristics of the DEH valve and modifying the control parameters of the single valve and sequence valve are of great significance to improve the primary FM capability of the thermal power generation unit and ensure the safe and stable operation of the new power system. Therefore, in the field of thermal power plant thermal automation control technology, how to overcome the shortcomings of existing technology is a problem to be solved. Summary of the Invention

[0004] The valve flow characteristic curve used in DCS does not match the actual valve flow characteristic, and the overall valve position command change of the unit shows a large nonlinear relationship with the generated steam flow rate and unit load, affecting the primary frequency modulation response speed and adjustment effect of the thermal power generation unit, and this problem has not been solved. The purpose of the present invention is to provide a method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics to solve the shortcomings of the prior art, by analyzing the unit DEH valve flow characteristics through testing, establishing the valve flow characteristic curve, and correcting the control parameters of the single valve and sequence valve, so that the overall valve position command change of the unit shows an approximately linear relationship with the generated steam flow rate and unit load.

[0005] In order to achieve the above objectives, the technical solutions adopted in the present invention are as follows:

[0006] The method to correct single valve and sequence valve parameters based on the DEH valve flow characteristics is Data collection: switch the unit to DEH valve control mode, switch the unit's primary frequency modulation control, switch the unit's AGC control, switch the machine and furnace coordinated control to manual, switch the unit fuel automatic, switch the intake oxygen automatic, turn on the unit main steam temperature automatic, feed water automatic, and furnace pressure automatic, perform single-step 5% step disturbance of the single high pressure control valve from 100 to 0% and 0 to 100%, when a control valve is working, all other control valves are open, and after the operation of the single high pressure control valve is completed, all control valves are kept fully open, and then the control valves are gradually closed in the reverse order of the sequence valve input in 5% steps until the control valve is kept fully open in the final stage, and record the unit load, main steam pressure before the machine, pressure regulator pressure, main steam temperature, and temperature after the pressure regulator during the entire adjustment process (1); Flow characteristic curve calculation: Step (2) of calculating the flow characteristic curve of each high pressure control valve according to the Flugel equation using the data obtained in step (1); Parameter correction of each branch high pressure control valve in single valve control mode: In single valve control mode, calculate the actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, and find the high order continuous function y = f (x), the polygon function currently used by the unit single valve in DCS, and use the high order continuous function y = f (x) to correct the overall valve position command or valve opening; (3) Parameter correction for each branch high pressure control valve in sequence valve control mode: In sequence valve control mode, there are a number of steps from full open to full closed for all control valves. When the valve is fully open, the valve is closed in sequence according to the closing order until the final stage is fully open. The number of inflection points that occurs during the process is a-1, and the relative flow rate corresponding to the inflection points is y m and (4) calculating In the DCS, in the sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; The actual normalized relative flow rate of each high-pressure control valve is y, the corresponding valve opening is x, and the high-pressure control valve high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point m And according to the high-order continuous function y=f(x) and polygon function of each high pressure control valve, the correlation between the overall valve position and the relative flow rate is calculated, and the overall valve position command or the valve opening is corrected according to the correlation.

[0007] Further, preferably, in step (1), the recording sampling interval during recording is 1 s.

[0008] Further, preferably, step (2) specifically comprises: When the unit is under the i-th high pressure regulating valve opening degree j, j ∈ [0, 100%], TIFF2025502588000002.tif21170 Corrected based on the steam temperature before and after the high pressure regulating valve, TIFF2025502588000003.tif31170, where PT ij is the main steam pressure before the machine when the i-th high pressure control valve is open to j, in units of MPa. P1 ij is the regulator pressure when the i-th high pressure control valve opening degree j, in MPa. TS ij is the main steam temperature before the machine when the i-th high pressure control valve is open at j, in °C. T1 ij is the temperature downstream of the pressure regulator when the i-th high pressure control valve is open at j, and is expressed in °C.

[0009] Normalize the relative flow rate within the test range from 0 to 100%: TIFF2025502588000004.tif7170, where FRij% is the relative flow rate when the i-th high pressure control valve opening degree is j, F Ri0 is the corrected steam pressure ratio when the i-th high pressure control valve is opened to 0%, F Ri100 is the corrected steam pressure ratio when the i-th high pressure control valve is opened 100%, Based on the obtained relative flow rates, a flow rate characteristic curve of the i-th high pressure control valve is drawn.

[0010] Further, preferably, in step (3), calculating the actual single-valve normalized relative flow rate specifically includes: TIFF2025502588000005.tif13170, where TIFF2025502588000006.tif6170 is the actual single-valve normalized relative flow rate, i is the number of high-pressure regulating valves, j is the high-pressure regulating valve opening, j ∈ [0, 100%], Find the polygon function currently used by the unit single valve in the DCS, in which Yn is the discrete integrated valve position command, Xn is the valve opening corresponding to Yn, and the actual single valve normalized relative flow rate By fitting TIFF2025502588000007.tif7170 as y and the corresponding valve opening as x, a high-order continuous function y=f(x) is obtained. Substitute Xn in the polygon function into the high-order continuous function after the fitting to obtain the corrected overall valve position command Yn', or use the inverse function method x=f -1 Using (y), Yn in the polygon function is substituted into the solution of the high-order continuous function to obtain the corrected valve opening Xn'.

[0011] Further, preferably, the method of step (4) specifically comprises: In a sequence valve control mode, there are a number of steps from fully open to fully closed for all control valves, and when a valve is fully open, the number of inflection points that occurs during the process of sequentially closing the valves according to the closing order until the final stage is fully open is a-1, the inflection point number corresponding to the first valve that is closed is m=1, the inflection point number corresponding to the second valve that is closed is m=2, and so on until the final inflection point number is m=a-1; Relative flow rate y corresponding to the inflection point m Calculate In the TIFF2025502588000008.tif12170 formula, P m is the unit load corresponding to the m-th inflection point, and P e is the unit load when the valve is fully open, In the DCS, in the sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; Actual normalized relative flow rate F of each high pressure control valve Rij% The high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point m And each high pressure control valve high order continuous function y=f(x), according to the polygon function, calculate the correlation between the overall valve position and the relative flow rate to obtain, specifically, 1. Determine the overall valve position command and relative flow rate of each inflection point, that is, find the overall valve position command of all inflection points from the polygon function, and correspond to the relative flow rate corresponding to the calculated inflection points; 2. If the overall valve position is within the range of [0, a-1th inflection point corresponding to the overall valve position command], the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value of all high pressure control valves that need to be open within this range under that overall valve position. iThe average value of the values ​​is calculated, and multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the total valve position. 3. When the overall valve position is within the range of (the overall valve position command corresponding to the a-1th inflection point, the overall valve position command corresponding to the a-2th inflection point), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. i The average value of the values ​​is calculated, and multiplied by (the relative flow rate corresponding to the a-2th inflection point-the relative flow rate corresponding to the a-1th inflection point)+the relative flow rate corresponding to the a-1th inflection point to obtain the actual relative flow rate corresponding to the total valve position, and so on. 4. If the overall valve position is within the range of (the overall valve position command corresponding to the first inflection point, 1), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. i Average the values ​​and multiply them by (the relative flow rate corresponding to the first inflection point - the relative flow rate corresponding to the second inflection point) + the relative flow rate corresponding to the second inflection point to obtain an actual relative flow rate corresponding to the overall valve position; Then, the overall valve position command or the valve opening is corrected based on the correlation.

[0012] Additionally, the point in the control relationship where the deviation from the theoretical curve is greatest is preferably corrected.

[0013] The present invention also provides a system for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics, and adopts a method for correcting single valve and sequence valve parameters based on the above-mentioned DEH valve flow characteristics; a data collection module configured to collect, during the test process, unit load, main steam pressure before the machine, pressure regulator pressure, main steam flow rate, feedwater flow rate, main steam deheat water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and steam turbine total energy flow rate; a data processing module configured to calculate a flow characteristic curve of each high pressure control valve using the Flugel equation based on the data collected by the data collection module; a parameter correction module for each branch high-pressure control valve in the single valve control mode, configured to calculate an actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x to obtain a high-order continuous function y=f(x), find a polygon function currently used in the unit single valve in the DCS, and use the high-order continuous function y=f(x) to correct the overall valve position command or the valve opening; Relative flow rate y corresponding to the inflection point m Calculate the polygon function used by each control valve in sequence valve control mode in DCS, in which Yqi is the discrete integrated valve position command, Xqi is the corresponding valve opening, and the actual normalized relative flow rate of each high pressure control valve is y and the corresponding valve opening is x, and then fit each high pressure control valve with a high order continuous function y i =f i (x), where i is the i-th high pressure control valve, and the relative flow rate y corresponding to the inflection point is obtained. m and a parameter correction module for each branch high-pressure control valve in a sequence valve control mode, which is configured to calculate a correlation between the overall valve position and the relative flow rate based on a high-order continuous function y=f(x) and a polygon function of each high-pressure control valve, and correct the overall valve position command or the valve opening based on the correlation.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The valve flow characteristic curve currently used in DCS (Distributed Control System) does not match the actual valve flow characteristic, and the overall valve position command change of the unit has a large nonlinearity with respect to the generated steam flow and unit load, resulting in serious over-regulation or under-regulation of primary frequency modulation, and the coordinated control system will produce an adverse regulation effect, thus inducing system low-frequency oscillation. The present invention proposes a method for correcting single valve and sequence valve parameters based on DEH (Digital Electro-Hydraulic) valve flow characteristic.

[0016] The method of the present invention is based on field test data, and the results obtained are more targeted and practical, and can well adapt to the actual conditions of the unit. The test time of the method of the present invention is about 2 hours, the test process is simple and easy to operate, and the relative flowmeter algorithm and curve fitting method are clearer, more intuitive and time-saving compared with other methods, and can be applied to different thermal power generation units and can be universally applied. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing the arrangement of steam turbine valve nozzles. [Diagram 2] FIG. 13 is a diagram showing the theoretical and actual correspondence relationship between the normalized total valve position command and the relative flow rate. [Diagram 3] 1 is a schematic diagram showing the structure of a system for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics of the present invention. The arrow direction is the data or signal direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In the following the invention will be explained in more detail with reference to examples.

[0019] Those skilled in the art should understand that the following examples are used only for the purpose of illustrating the present invention, and are not intended to limit the scope of the present invention. In the examples, if no specific techniques or conditions are shown, they are in accordance with the techniques or conditions or product specifications described in the literature in this field. If the materials or equipment used do not have the manufacturer's name, they are conventional products available for purchase.

[0020] Example 1 The method to correct single valve and sequence valve parameters based on the DEH valve flow characteristics is Data collection: switch the unit to DEH valve control mode, switch the unit's primary frequency modulation control, switch the unit's AGC control, switch the machine and furnace coordinated control to manual, switch the unit fuel automatic, switch the intake oxygen automatic, turn on the unit main steam temperature automatic, feed water automatic, and furnace pressure automatic, perform single-step 5% step disturbance of the single high pressure control valve from 100 to 0% and 0 to 100%, when a control valve is working, all other control valves are open, and after the operation of the single high pressure control valve is completed, all control valves are kept fully open, and then the control valves are gradually closed in the reverse order of the sequence valve input in 5% steps until the control valve is kept fully open in the final stage, and record the unit load, main steam pressure before the machine, pressure regulator pressure, main steam temperature, and temperature after the pressure regulator during the entire adjustment process (1); Flow characteristic curve calculation: Step (2) of calculating the flow characteristic curve of each high pressure control valve according to the Flugel equation using the data obtained in step (1); Parameter correction of each branch high pressure control valve in single valve control mode: In single valve control mode, calculate the actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, and find the high order continuous function y = f (x), the polygon function currently used by the unit single valve in DCS, and use the high order continuous function y = f (x) to correct the overall valve position command or valve opening; (3) Parameter correction for each branch high pressure control valve in sequence valve control mode: In sequence valve control mode, there are a number of steps from full open to full closed for all control valves. When the valve is fully open, the valve is closed in sequence according to the closing order until the final stage is fully open. The number of inflection points that occurs during the process is a-1, and the relative flow rate corresponding to the inflection points is y m and (4) calculating In the DCS, in the sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; The actual normalized relative flow rate of each high-pressure control valve is y, the corresponding valve opening is x, and the high-pressure control valve high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point m And according to the high-order continuous function y=f(x) and polygon function of each high pressure control valve, the correlation between the overall valve position and the relative flow rate is calculated, and the overall valve position command or the valve opening is corrected according to the correlation.

[0021] Example 2 The method to correct single valve and sequence valve parameters based on the DEH valve flow characteristics is Data collection: switch the unit to DEH valve control mode, switch the unit's primary frequency modulation control, switch the unit's AGC control, switch the machine and furnace coordinated control to manual, switch the unit fuel automatic, switch the intake oxygen automatic, turn on the unit main steam temperature automatic, feed water automatic, and furnace pressure automatic, perform single-step 5% step disturbance of the single high pressure control valve from 100 to 0% and 0 to 100%, when a control valve is working, all other control valves are open, and after the operation of the single high pressure control valve is completed, all control valves are kept fully open, and then the control valves are gradually closed in the reverse order of the sequence valve input in 5% steps until the control valve is kept fully open in the final stage, and record the unit load, main steam pressure before the machine, pressure regulator pressure, main steam temperature, and temperature after the pressure regulator during the entire adjustment process (1); Flow characteristic curve calculation: Step (2) of calculating the flow characteristic curve of each high pressure control valve according to the Flugel equation using the data obtained in step (1); Parameter correction of each branch high pressure control valve in single valve control mode: In single valve control mode, calculate the actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, and find the high order continuous function y = f (x), the polygon function currently used by the unit single valve in DCS, and use the high order continuous function y = f (x) to correct the overall valve position command or valve opening; (3) Parameter correction for each branch high pressure control valve in sequence valve control mode: In sequence valve control mode, there are a number of steps from full open to full closed for all control valves. When the valve is fully open, the valve is closed in sequence according to the closing order until the final stage is fully open. The number of inflection points that occurs during the process is a-1, and the relative flow rate corresponding to the inflection points is y m and (4) calculating In the DCS, in the sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; The actual normalized relative flow rate of each high-pressure control valve is y, the corresponding valve opening is x, and the high-pressure control valve high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point m And according to the high-order continuous function y=f(x) and polygon function of each high pressure control valve, the correlation between the overall valve position and the relative flow rate is calculated, and the overall valve position command or the valve opening is corrected according to the correlation.

[0022] In step (1), the recording sampling interval is 1 s. The unit is under the i-th high pressure regulating valve opening degree j, j ∈ [0, 100%], before and after the high pressure regulating valve. TIFF2025502588000009.tif21170 Corrected based on the steam temperature before and after the high pressure regulating valve. TIFF2025502588000010.tif31170, where PT ij is the main steam pressure before the machine when the i-th high pressure control valve is open to j, in units of MPa. P1 ij is the regulator pressure when the i-th high pressure control valve opening degree j, in MPa. TS ij is the main steam temperature before the machine when the i-th high pressure control valve is open at j, in °C. T1 ij is the temperature downstream of the pressure regulator when the i-th high pressure control valve is open at j, and is expressed in °C.

[0023] Normalize the relative flow rate within the test range from 0 to 100%: TIFF2025502588000011.tif7170, where F Rij% is the relative flow rate when the i-th high pressure control valve opening degree is j, F Ri0 is the corrected steam pressure ratio when the i-th high pressure control valve is opened to 0%, F Ri100 is the corrected steam pressure ratio when the i-th high pressure control valve is opened 100%, Based on the obtained relative flow rates, a flow rate characteristic curve of the i-th high pressure control valve is drawn.

[0024] In step (3), calculating the actual single-valve normalized relative flow rate specifically includes: TIFF2025502588000012.tif13170, where TIFF2025502588000013.tif7170 is the actual single-valve normalized relative flow rate, i is the number of high-pressure regulating valves, j is the high-pressure regulating valve opening, j ∈ [0, 100%], Find the polygon function currently used by the unit single valve in the DCS, in which Yn is the discrete integrated valve position command, Xn is the valve opening corresponding to Yn, and the actual single valve normalized relative flow rate By fitting TIFF2025502588000014.tif7170 as y and the corresponding valve opening as x, a high-order continuous function y=f(x) is obtained. Substitute Xn in the polygon function into the high-order continuous function after the fitting to obtain the corrected overall valve position command Yn', or use the inverse function method x=f -1 Using (y), Yn in the polygon function is substituted into the solution of the high-order continuous function to obtain the corrected valve opening Xn'.

[0025] Step (4) Specific method: In a sequence valve control mode, there are a number of steps from fully open to fully closed for all control valves, and when a valve is fully open, the number of inflection points that occurs during the process of sequentially closing the valves according to the closing order until the final stage is fully open is a-1, the inflection point number corresponding to the first valve that is closed is m=1, the inflection point number corresponding to the second valve that is closed is m=2, and so on until the final inflection point number is m=a-1; Relative flow rate y corresponding to the inflection point m Calculate In the TIFF2025502588000015.tif12170 formula, P m is the unit load corresponding to the m-th inflection point, and P e is the unit load when the valve is fully open, In the DCS, in the sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; Actual normalized relative flow rate F of each high pressure control valve Rij% The high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point m And each high pressure control valve high order continuous function y=f(x), according to the polygon function, calculate the correlation between the overall valve position and the relative flow rate to obtain, specifically, 1. Determine the overall valve position command and relative flow rate of each inflection point, that is, find the overall valve position command of all inflection points from the polygon function, and correspond to the relative flow rate corresponding to the calculated inflection points; 2. If the overall valve position is within the range of [0, a-1th inflection point corresponding to the overall valve position command], the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value of all high pressure control valves that need to be open within this range under that overall valve position. i The average value of the values ​​is calculated, and multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the total valve position. 3. When the overall valve position is within the range of (the overall valve position command corresponding to the a-1th inflection point, the overall valve position command corresponding to the a-2th inflection point), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. iThe average value of the values ​​is calculated, and multiplied by (the relative flow rate corresponding to the a-2th inflection point-the relative flow rate corresponding to the a-1th inflection point)+the relative flow rate corresponding to the a-1th inflection point to obtain the actual relative flow rate corresponding to the total valve position, and so on. 4. If the overall valve position is within the range of (the overall valve position command corresponding to the first inflection point, 1), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. i Average the values ​​and multiply them by (the relative flow rate corresponding to the first inflection point - the relative flow rate corresponding to the second inflection point) + the relative flow rate corresponding to the second inflection point to obtain an actual relative flow rate corresponding to the overall valve position; Then, the overall valve position command or the valve opening is corrected based on the correlation.

[0026] The point of greatest deviation from the theoretical curve in the control relationship is corrected.

[0027] As shown in FIG. 3, the system for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics adopts a method for correcting single valve and sequence valve parameters based on the above-mentioned DEH valve flow characteristics, a data collection module 101 configured to collect, during the test process, unit load, main steam pressure before the machine, pressure regulator pressure, main steam flow rate, feed water flow rate, main steam deheat water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and steam turbine total energy flow rate; a data processing module 102 configured to calculate a flow characteristic curve of each high pressure control valve using the Flugel equation based on the data collected by the data collection module; a parameter correction module 103 for each branch high-pressure control valve in the single valve control mode, configured to calculate an actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, obtain a high-order continuous function y=f(x), find a polygon function currently used in the unit single valve in the DCS, and use the high-order continuous function y=f(x) to correct the overall valve position command or the valve opening; Relative flow rate y corresponding to the inflection point m Calculate the polygon function used by each control valve in sequence valve control mode in DCS, in which Yqi is the discrete integrated valve position command, Xqi is the corresponding valve opening, and the actual normalized relative flow rate of each high pressure control valve is y and the corresponding valve opening is x, and then fit each high pressure control valve with a high order continuous function y i =f i (x), where i is the i-th high pressure control valve, and the relative flow rate y corresponding to the inflection point is obtained. m and a parameter correction module 104 for each branch high-pressure control valve in a sequence valve control mode, which is configured to calculate and obtain a correlation between the overall valve position and the relative flow rate based on a high-order continuous function y=f(x) and a polygon function of each high-pressure control valve, and to correct the overall valve position command or the valve opening based on the correlation.

[0028] Example 3 The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics includes the steps of: (1) On-site test. Set the effective output of the test unit to the load Pe when the valve is fully open, switch the unit to the DEH valve control mode, switch the unit's primary frequency modulation control, switch the unit's AGC control, switch the machine and furnace coordinated control to manual, switch the unit's fuel automatic, switch the intake oxygen automatic, turn on the unit's main steam temperature automatic, feedwater automatic, and furnace pressure automatic, perform single high pressure control valve 100-0% and 0-100% single step 5% step disturbance, when a control valve is working, the other control valves are all open, and after the operation of the single high pressure control valve is completed, all control valves are kept fully open, and then gradually close the control valve according to the reverse sequence of the sequence valve opening in 5% steps until the control valve is kept fully open in the final stage, and record the important parameters such as unit load P, main steam pressure before the machine PT, pressure regulator pressure P1, main steam temperature TS, and temperature after pressure regulator T1 during the adjustment process.

[0029] (2) Select an appropriate numerical calculation method for the DEH valve flow characteristics, and calculate the flow rate of the DEH valve before and after the i-th high pressure regulating valve opening degree j (j ∈ [0, 100%]). TIFF2025502588000016.tif21170Different boundary conditions are corrected based on the steam temperature before and after the high pressure regulating valve. It should be larger than TIFF2025502588000017.tif7170. TIFF2025502588000018.tif24170, where PT ij is the main steam pressure before the machine when the i-th high pressure control valve is open to j, in units of MPa. P1 ij is the regulator pressure when the i-th high pressure control valve opening degree j, in MPa. TS ij is the main steam temperature before the machine when the i-th high pressure control valve is open at j, in °C. T1 ij is the temperature downstream of the pressure regulator when the i-th high pressure control valve is open at j, and is expressed in °C.

[0030] Normalize the relative flow rate within the test range from 0 to 100%: TIFF2025502588000019.tif7170, where F Rij% is the relative flow rate when the i-th high pressure control valve opening degree is j, F Ri0 is the corrected steam pressure ratio when the i-th high pressure control valve is opened to 0%, F Ri100 is the corrected steam pressure ratio when the i-th high pressure control valve is 100% open.

[0031] (3) Correct the parameters of each branch high pressure control valve in single valve control mode. Under single valve operation mode, the steam passes through the high pressure regulating valve and the nozzle chamber, and enters the 360°C full circumference pressure regulating stage vane, which heats the pressure regulating stage vane evenly and effectively improves the stress distribution of the pressure regulating stage vane, allowing the unit to change load relatively quickly, at which time all the regulating valves are partially opened with the same opening (for example, each valve in single valve mode is opened with the same opening of 50%). In this case, the actual single valve normalized relative flow rate is: TIFF2025502588000020.tif13170, where: TIFF2025502588000021.tif6170 is the actual single-valve normalized relative flow rate, i is the number of high-pressure regulating valves, j is the high-pressure regulating valve opening, (j∈[0, 100%]), Find the polygon function currently used by the unit single valve in the DCS, in which the key parameters are the discrete integrated valve position command Yn and the corresponding valve opening Xn, where Yn and Xn are all normalized values.

[0032] In Matlab, call the polyfit and polyval functions to obtain the discretized TIFF2025502588000022.tif7170 is fitted to a high-order continuous function y=f(x). The normalized Xn can be substituted into the above fitted function to obtain the corrected total valve position command Yn'. Alternatively, the inverse function method x=f -1Through (y), Yn can be substituted into the solution of the high-order continuous function to obtain the corrected valve opening Xn'.

[0033] (4) Correct the parameters of each branch high pressure control valve in sequence valve control mode.

[0034] In sequence valve control mode, the regulating valves are opened sequentially according to the preset sequence valve flow characteristic curve of each valve, for example, a 300MW unit manufactured by Harbin Steam Turbine Factory with 6 high pressure regulating valves: the opening sequence is GV4 and GV5 open simultaneously → GV6 → GV3 → GV2 → GV1 open sequentially, and the closing sequence is reversed. Definition: In sequence valve control mode, there are a number of steps from full opening to full closing of all control valves, for example, a is 5 in the above example. In conjunction with the field test, when the valve is fully open, the valve is closed according to the closing sequence until the last stage is fully open, and the number of inflection points generated during this process is a-1. If the inflection point number is m, the inflection point number corresponding to the first closed valve is m=1, and the last inflection point number is m=a-1. The calculation formula is as follows: In the TIFF2025502588000023.tif12170 formula, P m is the unit load corresponding to the m-th inflection point, and P e is the unit load when the valve is fully open, In the DCS, in the sequence valve control mode, a polygon function is found to be used for each control valve, in which the key parameters are the discrete integrated valve position command Yqi and the corresponding valve opening Xqi, where Yqi and Xqi are all normalized values.

[0035] The polyfit and polyval functions were called in Matlab to calculate the normalized relative flow rate F of each high-pressure control valve. Rij% The high-order continuous function y i =f i (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point mAnd each high pressure control valve high order continuous function y=f(x), according to the polygon function, calculate the correlation between the overall valve position and the relative flow rate to obtain, specifically, 1. Determine the overall valve position command and relative flow rate of each inflection point, that is, find the overall valve position command of all inflection points from the polygon function, and correspond to the relative flow rate corresponding to the calculated inflection points; 2. If the overall valve position is within the range of [0, a-1th inflection point corresponding to the overall valve position command], the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value of all high pressure control valves that need to be open within this range under that overall valve position. i The average value of the values ​​is calculated, and multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the total valve position. 3. When the overall valve position is within the range of (the overall valve position command corresponding to the a-1th inflection point, the overall valve position command corresponding to the a-2th inflection point), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. i The average value of the values ​​is calculated, and multiplied by (the relative flow rate corresponding to the a-2th inflection point-the relative flow rate corresponding to the a-1th inflection point)+the relative flow rate corresponding to the a-1th inflection point to obtain the actual relative flow rate corresponding to the total valve position, and so on. 4. If the overall valve position is within the range of (the overall valve position command corresponding to the first inflection point, 1), the overall valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y i value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. iAverage the values ​​and multiply them by (the relative flow rate corresponding to the first inflection point - the relative flow rate corresponding to the second inflection point) + the relative flow rate corresponding to the second inflection point to obtain an actual relative flow rate corresponding to the overall valve position; Then, the overall valve position command or the valve opening is corrected based on the correlation.

[0036] Application examples The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics includes the steps of: (1) Field test is conducted on a 300MW coal-fired power generating unit as an example. The steam turbine manufacturing factory and model are Dongfang Steam Turbine Factory / N300-16.7 / 537 / 537. The steam turbine valve nozzle layout is as shown in Figure 1. There are a total of four high-pressure control valves. In the sequence valve mode, the opening order is GV1, GV2 open simultaneously → GV3 → GV4.

[0037] Under the test conditions, the load when the valve is fully open is basically stable at about 250MW, the unit is switched to DEH valve control mode, the unit is switched to primary frequency modulation control, the unit is switched to AGC control, the machine and furnace coordinated control is switched to manual, the unit fuel automatic is switched, the intake oxygen automatic is switched, the unit main steam temperature automatic, feedwater automatic, and furnace pressure automatic are turned on, and the single high pressure control valve is operated from 100 to 0% and 0 to 100% with a single step of 5% step disturbance.

[0038] As a result of collecting data, PT 1=[11.899 11.8343 11.8025 11.7816 11.739 11.7289 11.7083 11.6877 11.6877 11.6701 11.6701 11.6701 11.6701 11.6814 11.7033 11.7558 11.8018 11.8805 11.9997 12.0799 12.2543、12.3165 12.3985 12.4289 12.4617 12.4929 12.5034 12.5518 12.5518 12.5518 12.5518 12.5518 12.5518 12.5518 12.5317 12.5216 12.501 12.48 12.4684 12.4578 12.3699 12.2543]。

[0039] P1 1 =[9.9086 9.8544 9.8207 9.7987 9.7775 9.7569 9.732 9.7196 9.7196 9.7013 9.691 9.691 9.68 9.6661 9.6434 9.6075 9.5255 9.3966 9.2201 9.2046 9.3225、10.2512 10.3149 10.353 10.375 10.4131 10.4131 10.4468 10.4468 10.4468 10.4468 10.4468 10.4321 10.4168 10.3809 10.3289 10.2249 10.0806 9.8572 9.5723 9.4273 9.3225]。

[0040] TS 1= [533.3653 533.1078 533.3224 533.3224 533.923 534.1805 534.9099 535.6393 536.4116 537.2269 537.5272 538.1709 538.5142 538.9861 539.2436 539.2865 539.2865 539.501 539.7156 539.9302, 529.847 526.8438 526.5863 526.3718 526.3718 526.8438 527.616 528.3025 529.5038 531.1342 532.4213 533.9659 535.5964 536.8836 538.2138 539.0291 539.501 539.9731 539.9731 539.9302 539.9302].

[0041] T1 1 = [510.0246 510.0246 510.282 510.282 510.6253 511.226 512.0842 512.7278 513.3286 513.8864 514.4442 514.7875 515.1307 515.1307 515.1307 514.6158 513.4144 511.3119 507.879 506.5057 505.8191, 506.8061 503.7591 503.4587 502.9866 502.9866 503.2441 503.7591 504.36 505.2612 506.377 507.8361 508.9518 510.2391 511.5693 512.17 512.213 511.3548 509.3809 506.8061 505.8191 505.8191].

[0042] The above is the data collected by taking the first high pressure control valve as an example, which is similar to the data collected by the other three high pressure control valves and will not be repeated.

[0043] When the sequence valve is closed according to the opposite direction of opening, the unit load change is 253.86 MW→237.35 MW→187.85 MW.

[0044] As a result of calculation using formula (2), F R1j% =[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.986 0.968 0.942 0.890 0.794 0.650 0.416 0.100 0.015 0.000], where j is (100%, 5%, 0), i.e., starting from 100 and decreasing to 0 in intervals of 5, there are 21 numbers such as: F R2j% =[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.995 0.984 0.945 0.888 0.794 0.639 0.413 0.105 0.023 0.000]. F R3j% =[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.993 0.983 0.959 0.918 0.849 0.697 0.488 0.213 0.032 0.000]. F R4j% =[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.993 0.984 0.962 0.926 0.860 0.756 0.586 0.360 0.094 0.032 0.000].

[0045] (3) Correct the single valve control parameters.

[0046] As a result of calculation from the formula, F R単一バルブj%=[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 0.998 0.990 0.974 0.943 0.889 0.798 0.643 0.419 0.128 0.026 0.000].

[0047] The original single-valve normalized control parameters found from the DCS are shown in Table 1. TIFF2025502588000024.tif83170By using the matlab fitting function, for example, a 5th order polynomial function is selected for fitting, and the obtained functional relationship is y=-285.1282x 5 +488.5315x 4 -303.2191x 3 +75.8579x 2 -3.3862x+0.007972.

[0048] For example, if the valve opening is 0.228, the corrected overall valve position command should be 0.73; if the overall valve position command is 0.829, the corrected valve opening should be 0.378; or after finding the functional relationship, the entire polygon function may be modified according to customization.

[0049] According to the above principles, the single valve control parameters can be corrected as necessary.

[0050] (4) Correct the sequence valve control parameters.

[0051] According to the test data, there are two inflection points, the first inflection point corresponds to y1=237.35 / 253.86=0.9349, and the second inflection point corresponds to y2=187.35 / 253.86=0.738.

[0052] The currently used sequence valve control normalization parameters found in the DCS are shown in Table 2. TIFF2025502588000025.tif161170In Table 2, the actual inflection points are 0.899 for the first and 0.712 for the second, which are close to the situation measured in the field test, where the first inflection point is 0.9349 and the second is 0.738, and the overlap requirements are also met. Therefore, they can continue to be used in accordance with the use of most of the parameters of the power plant, and the calculations in this specification can also be used directly, that is, 0.712 in the GV3 overall valve position command column in Table 2 can be replaced with 0.738, and 0.899 in GV4 can be replaced with 0.9349.

[0053] The result of fitting the discrete data obtained in step (2) using Matlab is as follows: y 1 =-323.0769x 1 5 +550.7925x 1 4 -339.4231x 1 3 +84.6501x 1 2 -4.1412x 1 +0.0095559 y 2 =-301.0256x 2 5 +510.1748x 2 4 -315.1288x 2 3 +79.1236x 2 2 -3.753x 2 +0.0095332 y 3 =-393.8462x 3 5 +621.958x 3 4 -354.9324x 3 3 +80.9211x 3 2 -2.862x 3 +0.0025245 y 4 =-123.5897x 45 +273.8345x 4 4 -205.2558x 4 3 +59.2105x 4 2 -2.8227x 4 +0.0099773 Referring to the above table and the inflection point data, each valve opening is substituted into the above formula to calculate the corresponding relative flow rate. Furthermore, the comparison table between the relative flow rate and the overall valve position command under the currently used sequence valve parameters is shown in Table 3.

[0054] The specific calculation process is as follows: 1. Determine the overall valve position command and the relative flow rate of the two inflection points, that is, when the overall valve position command is 0.712, the relative flow rate is 0.738, and when the overall valve position command is 0.712, the relative flow rate is 0.9349.

[0055] 2. When the total valve position is less than or equal to 0.712, take the total valve position command of 0.585 as an example. In the original parameter settings, the openings of GV1 and GV2 are all 0.319. The two y values ​​obtained by substituting them into the above functional relationships are 0.9207 and 0.923, respectively. The average value of the two values ​​is multiplied by 0.738 to calculate the actual relative flow rate under these parameters is 0.68. Other values ​​can be referred to the calculated values.

[0056] 3. When the total valve position is greater than 0.712 and less than or equal to 0.899, take the case where the total valve position is 0.835 as an example, in the original parameter setting, the opening of GV3 is 0.206, and the y value obtained by substituting into the above functional relationship is 0.718. In this case, GV1 and GV2 are fully open, so this value 0.718 is multiplied by (0.9349-0.738) and then 0.738 is added to calculate, and the actual relative flow rate under these parameters is 0.879. Other values ​​can be referred to the calculated values.

[0057] 4. When the total valve position is greater than 0.899, take the case where the total valve position is 0.960 as an example. In the original parameter setting, the opening of GV4 is 0.206, and the y value obtained by substituting it into the above functional relationship is 0.594. In this case, GV1, GV2, and GV3 are fully open, so this value 0.594 is multiplied by (1-0.9349) and then 0.9349 is added to calculate, and the actual relative flow rate under these parameters is 0.974. Other values ​​can be referred to the calculated values. TIFF2025502588000026.tif76170Theoretically, the total valve position command and relative flow rate after normalization are The relationship is TIFF2025502588000027.tif6170, and the theoretical function and the actual curve are plotted on the same graph, see Figure 2.

[0058] For example, after comparison, it is found that when the overall valve position is 0.585, the corresponding valve opening needs to be corrected. As can be seen from Table 3, the relative flow rate obtained by the parameter calculation currently used is 0.68. Theoretically, the relative flow rate and the overall valve position command should have a direct proportional relationship, so the theoretical value is 0.585 and needs to be corrected. As can be seen from Table 2, when the overall valve position command is 0.585, only the first and second high pressure control valves are in operation, so the first and second high pressure control valves need to be corrected. Using the inverse function method, the first and second high pressure control valve openings need to be corrected from 0.319 to 0.25. The correction methods for the valve openings corresponding to other overall valve position commands are similar.

[0059] Strictly speaking, correction can be made as long as all points are not on the theoretical curve, i.e., the curve of a direct proportional relationship. However, in the field, correction is generally made according to the minimum range, i.e., only points that deviate significantly from the theoretical curve are corrected. Therefore, in the embodiment, the point with the greatest deviation is described as an example.

[0060] So far, the method for correcting sequence valve control parameters has been described.

[0061] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the description in the specification are merely illustrative of the principles of the present invention, and that various modifications and improvements can be made to the present invention without departing from the spirit and scope of the present invention, and all such modifications and improvements are included within the scope of the present invention that is intended to be protected. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Data collection: switch the unit to DEH valve control mode, switch the unit's primary frequency modulation control, switch the unit's AGC control, switch the machine and furnace coordinated control to manual, switch the unit fuel automatic, switch the intake oxygen automatic, turn on the unit main steam temperature automatic, feed water automatic, and furnace pressure automatic, perform single high pressure control valve 100-0% and 0-100% single step 5% step disturbance, when a control valve is working, other control valves are all open, after the operation of the single high pressure control valve is completed, all control valves are kept fully open, and then gradually close the control valves according to the reverse sequence of sequence valve input in 5% steps until the control valve is kept fully open in the final stage, and record the unit load, main steam pressure before the machine, pressure regulator pressure, main steam temperature, and temperature after the pressure regulator during the entire adjustment process; (1); Flow characteristic curve calculation: using the data obtained in step (1), calculate the flow characteristic curve of each high pressure control valve according to the Flugel equation (2); Parameter correction of each branch high pressure control valve in single valve control mode: In single valve control mode, calculate the actual single valve normalized relative flow rate, and fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, and find the high order continuous function y = f (x), and find the polygon function currently used by the unit single valve in DCS, and use the high order continuous function y = f (x) to correct the overall valve position command or valve opening; Parameter correction of each branch high pressure control valve in sequence valve control mode: In sequence valve control mode, there are a number of steps from full open to full closed for all control valves. When the valve is fully open, the valve is closed in sequence according to the closing order until the final stage is fully open. The number of inflection points that occurs during the process is a-1, and the relative flow rate y corresponding to the inflection points is ｍ and (4) calculating In the DCS, in sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; The actual normalized relative flow rate of each high-pressure control valve is set to y, the corresponding valve opening is set to x, and a high-order continuous function y ｉ = f ｉ (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point ｍ and calculating a correlation between the overall valve position and the relative flow rate based on the high-pressure control valve high-order continuous function y=f(x) and polygon function to obtain a correlation between the overall valve position and the relative flow rate, and correcting the overall valve position command or the valve opening based on the correlation.

2. 2. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics as claimed in claim 1, wherein in step (1), the recording sampling interval is 1 s during recording.

3. Specifically, step (2) is When the unit is under the i-th high pressure regulating valve opening degree j, j ∈ [0, 100%], Correction is made based on the steam temperature before and after the high pressure regulating valve. Here, P.T. ｉｊ is the main steam pressure before the machine when the i-th high pressure control valve opening degree j is reached, in units of MPa. P1 ｉｊ is the regulator pressure when the i-th high pressure control valve opening degree j, in units of MPa, T.S. ｉｊ is the main steam temperature before the machine when the i-th high pressure control valve is open to j, in °C. T1 ｉｊ is the temperature downstream of the pressure regulator when the i-th high pressure control valve opening degree j, and is expressed in °C. Normalize the relative flow rate within the test range from 0 to 100%: Here, F Ｒｉｊ％ is the relative flow rate when the i-th high pressure control valve opening degree j, F Ｒｉ０ is the corrected steam pressure ratio when the i-th high pressure control valve is opened to 0%, F Ｒｉ１００ is the corrected steam pressure ratio when the i-th high pressure control valve is opened 100%, 2. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics as claimed in claim 1, further comprising: drawing an i-th high pressure control valve flow characteristic curve based on the obtained relative flow rate.

4. In step (3), calculating the actual single-valve normalized relative flow rate specifically includes: Where: is the actual single-valve normalized relative flow rate, i is the number of high-pressure regulating valves, j is the high-pressure regulating valve opening, j ∈ [0, 100%], Find the polygon function currently used by the unit single valve in the DCS, in which Yn is the discrete integrated valve position command, Xn is the valve opening corresponding to Yn, and the actual single valve normalized relative flow rate is fitted with y and the corresponding valve opening degree x to obtain a high-order continuous function y = f(x), Substituting Xn in the polygon function into the high-order continuous function after the fitting to obtain the corrected overall valve position command Yn', or using the inverse function method x=f －１ The method for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics according to claim 3, characterized in that (y) is used to substitute Yn in the polygon function into solving a high-order continuous function to obtain the corrected valve opening Xn'.

5. The method of step (4) is specifically as follows: In the sequence valve control mode, there are a number of steps from fully open to fully closed for all control valves, and when the valves are fully open, the number of inflection points that occurs during the process of sequentially closing the valves according to the closing order until the final stage of fully opening is a-1, the inflection point number corresponding to the first valve closed is m=1, the inflection point number corresponding to the second valve closed is m=2, and so on until the final inflection point number is m=a-1, Relative flow rate y corresponding to the inflection point ｍ Calculate In the formula, P ｍ is the unit load corresponding to the m-th inflection point, and P ｅ is the unit load when the valve is fully open, In the DCS, in sequence valve control mode, find the polygon function used for each control valve, in which Yqi is the discrete integrated valve position command, and Xqi is the corresponding valve opening; Actual normalized relative flow rate F of each high pressure control valve Ｒｉｊ％ The high-pressure control valve is fitted with a high-order continuous function y ｉ = f ｉ (x), where i is the i-th high pressure control valve, Relative flow rate y corresponding to the inflection point ｍ And each high pressure control valve high order continuous function y = f (x), according to the polygon function, calculate the correlation between the overall valve position and the relative flow rate to obtain, specifically, 1. Determine the overall valve position command and the relative flow rate of each inflection point, i.e., find the overall valve position command of all inflection points from the polygon function, and correspond to the relative flow rate corresponding to the calculated inflection points; 2. If the total valve position is within the range of [total valve position command corresponding to 0, a-1th inflection point], the total valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y ｉ value of all high pressure control valves that need to be open within this range under that total valve position. ｉ The average value of the values ​​is calculated and multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the total valve position.

3. When the total valve position is within the range of (total valve position command corresponding to the a-1th inflection point, total valve position command corresponding to the a-2th inflection point), the total valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y ｉ value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. ｉ the average of the values ​​is calculated and multiplied by (the relative flow rate corresponding to the a-2 inflection point - the relative flow rate corresponding to the a-1 inflection point) + the relative flow rate corresponding to the a-1 inflection point to obtain the actual relative flow rate corresponding to the total valve position, and so on.

4. If the total valve position is within the range of (total valve position command corresponding to the first inflection point, 1), the total valve position is set as x and substituted into the high-order continuous function of each high-pressure control valve that needs to be opened within this range, and the corresponding y ｉ value, excluding the fully open high pressure control valve, and then y of all high pressure control valves that need to be open within this range under that total valve position. ｉ Average the values ​​and multiply them by (the relative flow rate corresponding to the first inflection point - the relative flow rate corresponding to the second inflection point) + the relative flow rate corresponding to the second inflection point to obtain an actual relative flow rate corresponding to the overall valve position; 4. The method for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics as claimed in claim 3, further comprising: correcting an overall valve position command or a valve opening degree based on the correlation.

6. 6. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics as claimed in claim 5, further comprising correcting the point where the deviation from the theoretical curve is the greatest in the contrast relationship.

7. A system for correcting single valve and sequence valve parameters based on DEH valve flow characteristics, the system employing the method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics according to any one of claims 1 to 4, comprising: a data collection module configured to collect, during the test process, unit load, main steam pressure before the machine, pressure regulator pressure, main steam flow rate, feedwater flow rate, main steam deheat water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and steam turbine total energy flow rate; a data processing module configured to calculate a flow characteristic curve of each high pressure control valve using the Flugel equation based on the data collected by the data collection module; a parameter correction module for each branch high pressure control valve in the single valve control mode, configured to calculate an actual single valve normalized relative flow rate, fit the actual single valve normalized relative flow rate as y and the corresponding valve opening as x, obtain a high order continuous function y=f(x), find a polygon function currently used in the unit single valve in the DCS, and use the high order continuous function y=f(x) to correct the overall valve position command or the valve opening; Relative flow rate y corresponding to the inflection point ｍ Calculate the polygon function used by each control valve in sequence valve control mode in DCS, in which Yqi is the discrete integrated valve position command, Xqi is the corresponding valve opening, and the actual normalized relative flow rate of each high pressure control valve is y and the corresponding valve opening is x, and fit each high pressure control valve with a high order continuous function y ｉ = f ｉ (x), where i is the i-th high pressure control valve, and the relative flow rate y corresponding to the inflection point is obtained. ｍ and a parameter correction module for each branch high-pressure control valve in a sequence valve control mode, the parameter correction module being configured to calculate a correlation between the overall valve position and the relative flow rate based on a high-order continuous function y=f(x) and a polygon function of each high-pressure control valve, and to correct an overall valve position command or a valve opening degree based on the correlation.

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