Method for correcting parameters of single valve and sequence valve based on flow characteristics of deh valve

Abstract

The application relates to a method for correcting single-valve and sequence-valve parameters based on DEH valve flow characteristics, and belongs to the technical field of thermal automatic control of thermal power plants. The system comprises a data acquisition module, a data processing module, a parameter correction module of each branch high regulating valve in a single-valve control mode, and a parameter correction module of each branch high regulating valve in a sequence-valve control mode. The application provides turbine regulating valve nonlinear compensation data. After linearization correction of DEH control, the comprehensive valve position instruction change of the turbine under load, the generated steam flow and the unit load are linearly corresponding changes, the rapidity and stability of the unit load control are improved, the oscillation of the unit load control is prevented, the control quality of the unit AGC and primary frequency modulation is improved, and the safe, stable, economic and reliable operation of the thermal power unit is of great significance.

Description

Technical Field

[0001] This invention belongs to the field of thermal power plant thermal automation control technology, specifically relating to a method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics. Background Technology

[0002] With the introduction of the "dual carbon" target, a new power system based on wind and solar power is under construction. However, the large-scale grid connection of new energy sources has brought many problems due to the inherent volatility and uncertainty of wind and solar power, with frequency issues being particularly prominent. The frequency problem caused by wind and solar power grid connection stems from their inherent output characteristics; volatility and uncertainty are one aspect, but insufficient rotational inertia leads to drooping after regulation, further deteriorating the frequency. In contrast, thermal power units, as a superior frequency regulation resource, can respond within approximately 30 seconds and, relying on their larger rotational inertia, ensure high frequency regulation efficiency.

[0003] Thermal power units play a crucial "ballast" role in new power systems and are an indispensable part of their construction. However, most units continue to use the valve characteristic curves specified at the turbine's factory, failing to consider the changes in valve flow characteristics caused by valve overhauls and adjustments made by various power plants during overhauls. This lack of testing and correction of the characteristic curves leads to inconsistencies between the valve flow characteristics used in the DCS and the actual valve flow characteristics. The resulting nonlinearity in the overall valve position command changes, steam flow, and unit load significantly impacts the primary frequency regulation response rate and control effectiveness of thermal power units. Re-identifying the DEH valve flow characteristics and correcting the control parameters in single and sequential valves is crucial for improving the primary frequency regulation capability of thermal power units and ensuring the safe and stable operation of new power systems. Therefore, overcoming the shortcomings of existing technologies is a pressing issue in the field of thermal power plant automation control technology. Summary of the Invention

[0004] The valve flow characteristic curves used in the DCS are inconsistent with the actual valve flow characteristics. The changes in the unit's overall valve position command exhibit significant nonlinearity with the generated steam flow and unit load, greatly affecting the primary frequency regulation response rate and regulation effect of the thermal power unit. This problem has remained unresolved. The purpose of this invention is to address the shortcomings of existing technologies by providing a method for correcting single-valve and sequence valve parameters based on DEH valve flow characteristics. Through experimental analysis of the unit's DEH valve flow characteristics, valve flow characteristic curves are established, and the control parameters in single-valve and sequence valves are corrected to achieve a near-linear relationship between the changes in the unit's overall valve position command and the generated steam flow and unit load.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for correcting parameters of single valves and sequence valves based on the flow characteristics of DEH valves includes the following steps:

[0007] Step (1), Data Acquisition: Switch the unit to DEH valve control mode, disconnect the unit's primary frequency regulation control, disconnect the unit's AGC control, switch the boiler-turbine coordination control to manual, disconnect the unit's automatic fuel supply, disconnect the automatic air supply oxygen supply, and activate the unit's automatic main steam temperature, automatic feedwater, and automatic furnace pressure. Perform a single step disturbance of 5% from 100% to 0% and from 0% to 100% for a single high-pressure valve. When a certain valve is activated, all other valves are opened. After the single high-pressure valve is activated, keep all valves fully open. Then, according to the 5% step, gradually close the valves in the reverse order of the sequence valve activation until the last stage valve is fully open. Record the unit load, main steam pressure before the turbine, regulating stage pressure, main steam temperature, and regulating stage temperature during the entire regulation process.

[0008] Step (2), Flow characteristic curve calculation: Using the data obtained in step (1), the flow characteristic curve of each high-pressure valve is calculated according to the relative flow calculation formula;

[0009] Step (3), parameter correction of each high-pressure regulating valve in single-valve control mode: Under single-valve control mode, calculate the actual single-valve per-unit relative flow rate; use the actual single-valve per-unit relative flow rate as y, and fit it with the corresponding valve opening as x to obtain the high-order continuous function y=f(x); find the piecewise linear function used by the single valve of the current unit in DCS; use the high-order continuous function y=f(x) to correct the comprehensive valve position command or valve opening.

[0010] Step (4), parameter correction for each high-pressure regulating valve in the sequence valve control mode: Under the sequence valve control mode, there are a steps from fully closed to fully open for all regulating valves; when the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1, and the relative flow rate y corresponding to the inflection point is calculated. m ;

[0011] In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening.

[0012] By standardizing the relative flow rate of each high-regulation valve as y, and fitting the corresponding valve opening as x, we obtain the high-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate;

[0013] Based on the relative flow y corresponding to the inflection pointm The high-order continuous function y=f(x) and piecewise linear function of each high-adjustment valve are calculated to obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

[0014] Furthermore, preferably, in step (1), the recording sampling interval is 1 second.

[0015] Furthermore, preferably, step (2) specifically includes:

[0016] With the unit at the opening degree j of high-pressure regulating valve i, j∈[0, 100%], the steam pressure ratio ε before and after the high-pressure regulating valve is... ij :

[0017]

[0018] The steam pressure ratio ε′ is corrected based on the steam temperature before and after the high-pressure regulating valve. ij ;

[0019]

[0020] Let F Rij =f(PT) ij P1 ij TS ij T1 ij );

[0021] Among them, PT ij The main steam pressure in front of the turbine is when the opening degree of the high-pressure regulating valve i is j, in MPa;

[0022] P1 ij The regulating stage pressure is given when the opening degree of high-pressure regulating valve i is j, in MPa.

[0023] TS ij The main steam temperature before the turbine is when the opening degree of high-pressure valve i is j, in °C;

[0024] T1 ij The temperature after the regulating stage when the opening degree of the high-regulating gate i is j, in °C.

[0025] The relative flow rates within the test range were normalized to 0-100% per unit:

[0026] F Rij％ =(F Rij -F Ri0 ) / (F Ri100 -F Ri0 )

[0027] Among them, F Rij％ The relative flow rate is when the opening of high-pressure gate i is j;

[0028] F Ri0 The corrected steam pressure ratio for valve i when the valve opening is 0%;

[0029] F Ri100 The corrected steam pressure ratio for valve i when the valve opening is 100%;

[0030] Based on the obtained relative flow rate, plot the flow characteristic curve of valve i, which is a high-adjustment valve.

[0031] Furthermore, preferably, in step (3), the per-unit relative flow rate of the actual single valve is calculated as follows:

[0032]

[0033] Where F R单阀j % represents the actual per-unit relative flow rate of a single valve;

[0034] i represents the number of high-pressure regulating valves; j represents the opening degree of the high-pressure regulating valves (j∈[0, 100%]);

[0035] In the DCS, locate the piecewise linear function used by the current unit's single valve. In this function, Yn is the discrete integrated valve position command, and Xn is the valve opening corresponding to Yn. Then, normalize the actual single valve's per-unit relative flow rate F. R单阀j％ Let y be the valve opening, and let x be the valve opening, then fit the valve to obtain a higher-order continuous function y = f(x).

[0036] Substituting Xn from the piecewise linear function into the fitted higher-order continuous function yields the corrected integrated valve position command Yn'; or using the inverse function method x = f -1 (y), by substituting Yn from the piecewise linear function into the solution of the higher-order continuous function, we obtain the corrected valve opening Xn'.

[0037] Furthermore, preferably, the specific method of step (4) is as follows:

[0038] In the sequential valve control mode, there are a steps from all valves to fully closed to fully open. When the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1. The inflection point number corresponding to the first closed valve is m=1, the inflection point number corresponding to the second closed valve is m=2, and so on, with the last inflection point number being m=a-1.

[0039] Calculate the relative flow rate y corresponding to the inflection point m ;

[0040]

[0041] In the formula, P mLet P be the unit load corresponding to the m-th inflection point. e Unit load when valve is fully open

[0042] In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening.

[0043] The actual high-frequency gate per-unit relative flow F Rij％ Let y be the valve opening, and let x be the valve opening. Then, fit the valve to obtain the higher-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate;

[0044] Based on the relative flow y corresponding to the inflection point m And for each high-regulation valve, the higher-order continuous function y=f(x) and the piecewise linear function are used to calculate and obtain the correlation between the overall valve position and the relative flow rate; specifically:

[0045] (1) Determine the comprehensive valve position command and relative flow rate for each inflection point, that is, find the comprehensive valve position command for all inflection points from the piecewise linear function and match it with the calculated relative flow rate corresponding to the inflection point;

[0046] (2) If the integrated valve position is within the range of [0, integrated valve position command corresponding to the (a-1)th inflection point], then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment gate that needs to be opened within this range to obtain the corresponding y. i The value is then used to calculate the y-value of all high-adjustment valves that need to be opened within this range under the given integrated valve position. i The average value is multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0047] (3) If the integrated valve position is within the range of (the integrated valve position command corresponding to the (a-1)th inflection point, the integrated valve position command corresponding to the (a-2)th inflection point), then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment gate that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the (a-2)th inflection point - relative flow rate corresponding to the (a-1)th inflection point) + relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position; and so on.

[0048] (4) If the integrated valve position is within the range of (the integrated valve position command corresponding to the first inflection point, 1], then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the first inflection point - relative flow rate corresponding to the second inflection point) + relative flow rate corresponding to the second inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0049] Subsequently, based on this comparison relationship, the overall valve position command or valve opening degree is corrected.

[0050] Furthermore, preferably, the point in the control relationship that deviates the most from the theoretical curve is corrected.

[0051] This invention also provides a system for correcting single valve and sequence valve parameters based on DEH valve flow characteristics. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics includes:

[0052] The data acquisition module is used to collect data during the test, including unit load, main steam pressure before the turbine, regulating stage pressure, main steam flow rate, feedwater flow rate, main steam desuperheating water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and total turbine energy flow.

[0053] The data processing module is used to calculate the flow characteristic curve of each high-pressure valve based on the data collected by the data acquisition module and the relative flow calculation formula.

[0054] The parameter correction module for each high-pressure valve in the single-valve control mode is used to calculate the actual single-valve per-unit relative flow rate; the actual single-valve per-unit relative flow rate is y, and the corresponding valve opening is x, to obtain a high-order continuous function y=f(x); the piecewise linear function used by the single valve of the current unit is found in the DCS; the high-order continuous function y=f(x) is used to correct the integrated valve position command or valve opening.

[0055] The parameter correction module for each high-pressure valve in the sequence valve control method is used to calculate the relative flow rate y corresponding to the inflection point. m In the DCS, find the piecewise linear function used by each branch control valve under sequential valve control mode. In this function, Yqi is the discrete comprehensive valve position command, and Xqi is the corresponding valve opening. Standardize the actual relative flow rate of each high-pressure control valve to y, and fit it with the corresponding valve opening to x to obtain the high-order continuous function y for each high-pressure control valve. i =f i (x); i is the i-th high-pitched gate; based on the relative flow y corresponding to the inflection point. mThe high-order continuous function y=f(x) and piecewise linear function of each high-adjustment valve are calculated to obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

[0056] Compared with the prior art, the beneficial effects of this invention are as follows:

[0057] To address the issue that the valve flow characteristic curves used in current DCS (Distributed Control System) do not match the actual valve flow characteristics, resulting in significant nonlinearity in the overall valve position command changes, the generated steam flow, and the unit load, leading to severe overshoot or undershoot in primary frequency regulation, reverse regulation in the coordinated control system, and even low-frequency oscillations in the power grid, this invention proposes a method for correcting single-valve and sequence valve parameters based on the valve flow characteristics of a DEH (Digital Electro-Hydraulic) turbine control system.

[0058] The method of this invention is based on field test data, and the results obtained are more targeted and practical, and can be well matched with the actual situation of the unit. The test time of this invention is about 2 hours, the test process is simple and easy to operate, and the method used is relative flow calculation method and curve fitting, which is clearer, more intuitive and time-saving than other methods, and is applicable to different thermal power units, and has universality. Attached Figure Description

[0059] Figure 1 This is a diagram showing the arrangement of valves and nozzles in a steam turbine.

[0060] Figure 2 This is a diagram showing the theoretical and practical correspondence between the standardized integrated valve position command and the relative flow rate;

[0061] Figure 3 This is a schematic diagram of the system for correcting single valve and sequence valve parameters based on the DEH valve flow characteristics of the present invention; the arrows indicate the direction of data or signals. Detailed Implementation

[0062] The present invention will now be described in further detail with reference to the embodiments.

[0063] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product instructions. Materials or equipment whose manufacturers are not specified are all conventional products that can be obtained by purchase.

[0064] Example 1

[0065] A method for correcting parameters of single valves and sequence valves based on the flow characteristics of DEH valves includes the following steps:

[0066] Step (1), Data Acquisition: Switch the unit to DEH valve control mode, disconnect the unit's primary frequency regulation control, disconnect the unit's AGC control, switch the boiler-turbine coordination control to manual, disconnect the unit's automatic fuel supply, disconnect the automatic air supply oxygen supply, and activate the unit's automatic main steam temperature, automatic feedwater, and automatic furnace pressure. Perform a single step disturbance of 5% from 100% to 0% and from 0% to 100% for a single high-pressure valve. When a certain valve is activated, all other valves are opened. After the single high-pressure valve is activated, keep all valves fully open. Then, according to the 5% step, gradually close the valves in the reverse order of the sequence valve activation until the last stage valve is fully open. Record the unit load, main steam pressure before the turbine, regulating stage pressure, main steam temperature, and regulating stage temperature during the entire regulation process.

[0067] Step (2), Flow characteristic curve calculation: Using the data obtained in step (1), the flow characteristic curve of each high-pressure valve is calculated according to the relative flow calculation formula;

[0068] Step (3), parameter correction of each high-pressure regulating valve in single-valve control mode: Under single-valve control mode, calculate the actual single-valve per-unit relative flow rate; use the actual single-valve per-unit relative flow rate as y, and fit it with the corresponding valve opening as x to obtain the high-order continuous function y=f(x); find the piecewise linear function used by the single valve of the current unit in DCS; use the high-order continuous function y=f(x) to correct the comprehensive valve position command or valve opening.

[0069] Step (4), parameter correction for each high-pressure regulating valve in the sequence valve control mode: Under the sequence valve control mode, there are a steps from fully closed to fully open for all regulating valves; when the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1, and the relative flow rate y corresponding to the inflection point is calculated. m ;

[0070] In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening.

[0071] By standardizing the relative flow rate of each high-regulation valve as y, and fitting the corresponding valve opening as x, we obtain the high-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate;

[0072] Based on the relative flow y corresponding to the inflection point mThe high-order continuous function y=f(x) and piecewise linear function of each high-adjustment valve are calculated to obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

[0073] Example 2

[0074] A method for correcting parameters of single valves and sequence valves based on the flow characteristics of DEH valves includes the following steps:

[0075] Step (1), Data Acquisition: Switch the unit to DEH valve control mode, disconnect the unit's primary frequency regulation control, disconnect the unit's AGC control, switch the boiler-turbine coordination control to manual, disconnect the unit's automatic fuel supply, disconnect the automatic air supply oxygen supply, and activate the unit's automatic main steam temperature, automatic feedwater, and automatic furnace pressure. Perform a single step disturbance of 5% from 100% to 0% and from 0% to 100% for a single high-pressure valve. When a certain valve is activated, all other valves are opened. After the single high-pressure valve is activated, keep all valves fully open. Then, according to the 5% step, gradually close the valves in the reverse order of the sequence valve activation until the last stage valve is fully open. Record the unit load, main steam pressure before the turbine, regulating stage pressure, main steam temperature, and regulating stage temperature during the entire regulation process.

[0076] Step (2), Flow characteristic curve calculation: Using the data obtained in step (1), the flow characteristic curve of each high-pressure valve is calculated according to the relative flow calculation formula;

[0077] Step (3), parameter correction of each high-pressure regulating valve in single-valve control mode: Under single-valve control mode, calculate the actual single-valve per-unit relative flow rate; use the actual single-valve per-unit relative flow rate as y, and fit it with the corresponding valve opening as x to obtain the high-order continuous function y=f(x); find the piecewise linear function used by the single valve of the current unit in DCS; use the high-order continuous function y=f(x) to correct the comprehensive valve position command or valve opening.

[0078] Step (4), parameter correction for each high-pressure regulating valve in the sequence valve control mode: Under the sequence valve control mode, there are a steps from fully closed to fully open for all regulating valves; when the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1, and the relative flow rate y corresponding to the inflection point is calculated. m ;

[0079] In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening.

[0080] By standardizing the relative flow rate of each high-regulation valve as y, and fitting the corresponding valve opening as x, we obtain the high-order continuous function y for each high-regulation valve. i=f i (x); i is the i-th high-key gate;

[0081] Based on the relative flow y corresponding to the inflection point m The high-order continuous function y=f(x) and piecewise linear function of each high-adjustment valve are calculated to obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

[0082] In step (1), the recording sampling interval is 1 second.

[0083] Step (2) specifically involves:

[0084] With the unit at the opening degree j of high-pressure regulating valve i, j∈[0, 100%], the steam pressure ratio ε before and after the high-pressure regulating valve is... ij :

[0085]

[0086] The steam pressure ratio ε′ is corrected based on the steam temperature before and after the high-pressure regulating valve. ij ;

[0087]

[0088] Let FR ij =f(PT) ij P1 ij TS ij T1 ij );

[0089] Among them, PT ij The main steam pressure in front of the turbine is when the opening degree of the high-pressure regulating valve i is j, in MPa;

[0090] P1 ij The regulating stage pressure is given when the opening degree of high-pressure regulating valve i is j, in MPa.

[0091] TS ij The main steam temperature before the turbine is when the opening degree of high-pressure valve i is j, in °C;

[0092] T1 ij The temperature after the regulating stage when the opening degree of the high-regulating gate i is j, in °C.

[0093] The relative flow rates within the test range were normalized to 0-100% per unit:

[0094] F Rij％ =(F Rij -F Ri0 ) / (F Ri100 -F Ri0 )

[0095] Among them, F Rij % represents the relative flow rate when the opening degree of high-pressure gate i is j;

[0096] F Ri0 The corrected steam pressure ratio for valve i when the valve opening is 0%;

[0097] F Ri100 The corrected steam pressure ratio for valve i when the valve opening is 100%;

[0098] Based on the obtained relative flow rate, plot the flow characteristic curve of valve i, which is a high-adjustment valve.

[0099] In step (3), the actual per-unit relative flow rate of a single valve is calculated, specifically as follows:

[0100]

[0101] Where F R单阀j％ This represents the per-unit relative flow rate of a single valve.

[0102] i represents the number of high-pressure regulating valves; j represents the opening degree of the high-pressure regulating valves (j∈[0, 100%]);

[0103] In the DCS, locate the piecewise linear function used by the current unit's single valve. In this function, Yn is the discrete integrated valve position command, and Xn is the valve opening corresponding to Yn. Then, normalize the actual single valve's per-unit relative flow rate F. R单阀j％ Let y be the valve opening, and let x be the valve opening, then fit the valve to obtain a higher-order continuous function y = f(x).

[0104] Substituting Xn from the piecewise linear function into the fitted higher-order continuous function yields the corrected integrated valve position command Yn'; or using the inverse function method x = f -1 (y), by substituting Yn from the piecewise linear function into the solution of the higher-order continuous function, we obtain the corrected valve opening Xn'.

[0105] The specific method for step (4) is as follows:

[0106] In the sequential valve control mode, there are a steps from all valves to fully closed to fully open. When the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1. The inflection point number corresponding to the first closed valve is m=1, the inflection point number corresponding to the second closed valve is m=2, and so on, with the last inflection point number being m=a-1.

[0107] Calculate the relative flow rate y corresponding to the inflection point m ;

[0108]

[0109] In the formula, P m Let P be the unit load corresponding to the m-th inflection point. e Unit load when valve is fully open

[0110] In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening.

[0111] The actual high-frequency gate per-unit relative flow F Rij％ Let y be the valve opening, and let x be the valve opening. Then, fit the valve to obtain the higher-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate;

[0112] Based on the relative flow y corresponding to the inflection point m And for each high-regulation valve, the higher-order continuous function y=f(x) and the piecewise linear function are used to calculate and obtain the correlation between the overall valve position and the relative flow rate; specifically:

[0113] 1. Determine the overall valve position command and relative flow rate for each inflection point, that is, find the overall valve position command for all inflection points from the piecewise linear function and match it with the calculated relative flow rate corresponding to the inflection point;

[0114] 2. If the integrated valve position is within the range of [0, integrated valve position command corresponding to the (a-1)th inflection point], then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i The value is then used to calculate the y-value of all high-adjustment valves that need to be opened within this range under the given integrated valve position. i The average value is multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0115] 3. If the integrated valve position is within the range of (the integrated valve position command corresponding to the (a-1)th inflection point, and the integrated valve position command corresponding to the (a-2)th inflection point), then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the (a-2)th inflection point - relative flow rate corresponding to the (a-1)th inflection point) + relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position; and so on.

[0116] 4. If the integrated valve position is within the range of (the integrated valve position command corresponding to the first inflection point, 1], then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the first inflection point - relative flow rate corresponding to the second inflection point) + relative flow rate corresponding to the second inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0117] Subsequently, based on this comparison relationship, the overall valve position command or valve opening degree is corrected.

[0118] Corrections are made for the points in the control relationship that deviate the most from the theoretical curve.

[0119] like Figure 3 As shown, a system for correcting single valve and sequence valve parameters based on DEH valve flow characteristics adopts the aforementioned method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics, including:

[0120] The data acquisition module 101 is used to collect data during the test, including unit load, main steam pressure before the turbine, regulating stage pressure, main steam flow rate, feedwater flow rate, main steam desuperheating water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and total turbine energy flow.

[0121] Data processing module 102 is used to calculate the flow characteristic curve of each high-pressure valve based on the data collected by the data acquisition module and the relative flow calculation formula.

[0122] The parameter correction module 103 for each high-pressure valve in the single-valve control mode is used to calculate the actual single-valve per-unit relative flow rate; the actual single-valve per-unit relative flow rate is y, and the corresponding valve opening is x, to obtain a high-order continuous function y=f(x); the piecewise linear function used by the current unit single valve is found in the DCS; the high-order continuous function y=f(x) is used to correct the comprehensive valve position command or valve opening.

[0123] The parameter correction module 104 for each high-pressure valve in the sequence valve control method is used to calculate the relative flow rate y corresponding to the inflection point. m In the DCS, find the piecewise linear function used by each branch control valve under sequential valve control mode. In this function, Yqi is the discrete comprehensive valve position command, and Xqi is the corresponding valve opening. Standardize the actual relative flow rate of each high-pressure control valve to y, and fit it with the corresponding valve opening to x to obtain the high-order continuous function y for each high-pressure control valve. i =f i (x); i is the i-th high-pitched gate; based on the relative flow y corresponding to the inflection point.m The high-order continuous function y=f(x) and piecewise linear function of each high-adjustment valve are calculated to obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

[0124] Example 3

[0125] A method for correcting parameters of single valves and sequence valves based on the flow characteristics of DEH valves includes the following steps:

[0126] (I) Conduct on-site tests. Bring the active power output of the test unit to a load of Pe when the valves are fully open. Switch the unit to DEH valve control mode, disconnect the unit's primary frequency regulation control, disconnect the unit's AGC control, switch the boiler-turbine coordination control to manual, disconnect the unit's automatic fuel supply control, disconnect the automatic air supply oxygen supply control, and activate the unit's automatic main steam temperature control, automatic feedwater control, and automatic furnace pressure control. Perform single-step 5% step disturbances of 100% to 0% and 0% to 100% for individual high-pressure regulating valves. When a certain regulating valve is activated, all other regulating valves are opened. After the single high-pressure regulating valve is activated, keep all regulating valves fully open. Then, gradually close the regulating valves in the reverse order of the sequential valve activation according to the 5% step, until the last stage of regulating valves is fully open. Record the important parameters such as unit load P, main steam pressure PT before the turbine, regulating stage pressure P1, main steam temperature TS, and regulating stage temperature T1 during the regulation process.

[0127] (ii) Select a numerical calculation method suitable for the flow characteristics of the DEH valve, taking the steam pressure ratio ε before and after the high-pressure regulating valve j (j∈[0, 100%)) as the unit is in the condition of the opening degree j of the i-th high-pressure regulating valve. ij :

[0128]

[0129] Different boundary conditions should be corrected according to the steam temperature before and after the high-pressure regulating valve. The corrected steam pressure ratio is ε'. ij .

[0130]

[0131] Let F Rij =f(PT) ij P1 ij ,TS ij T1 ij ).

[0132] Among them, PT ij The main steam pressure in front of the turbine is when the opening degree of the high-pressure regulating valve i is j, in MPa;

[0133] P1 ij The regulating stage pressure is given when the opening degree of high-pressure regulating valve i is j, in MPa.

[0134] TS ij The main steam temperature before the turbine is when the opening degree of high-pressure valve i is j, in °C;

[0135] T1 ij The temperature after the regulating stage when the opening degree of the high-regulating gate i is j, in °C.

[0136] The relative flow rates within the test range were normalized to 0-100% per unit:

[0137] F Rij％ =(F Rij -F Ri0 ) / (F Ri100 -F Ri0 )

[0138] Among them, F Rij％ The relative flow rate is when the opening of high-pressure gate i is j;

[0139] F Ri0 The corrected steam pressure ratio for valve i when the valve opening is 0%;

[0140] F Ri100 This is the corrected steam pressure ratio for valve i when the valve opening is 100%.

[0141] (III) Parameter correction for each high-pressure regulating valve in single-valve control mode. In single-valve operation, steam passes through the high-pressure regulating valve and nozzle chamber, entering the regulating stage blades at a full 360°C. The regulating stage blades are heated evenly, effectively improving stress distribution and allowing the unit to change load more quickly. At this time, all regulating valves are partially open with the same opening degree (e.g., in single-valve mode, all valves have the same opening degree, 50%). Under these conditions, the actual single-valve per-unit relative flow rate is:

[0142]

[0143] Where F R单阀j％ is the actual single-valve per-unit relative flow rate; i is the number of high-pressure regulating valves; j is the opening degree of the high-pressure regulating valve (j∈[0, 100%]);

[0144] In the DCS, find the piecewise linear function used by the single valve of the current unit. The important parameters in this function are the discrete integrated valve position command Yn and its corresponding valve opening Xn. Here, Yn and Xn are both normalized values.

[0145] In MATLAB, call the polyfit and polyval functions to convert discrete F... R单阀j％The function is fitted to a high-order continuous function y = f(x). Substituting the normalized Xn into the fitted function yields the corrected integrated valve position command Yn'. Alternatively, the inverse function method x = f -1 (y), by substituting Yn into the solution of higher-order continuous functions, the corrected valve opening Xn' can be obtained.

[0146] (iv) Correct the parameters of each high-pressure valve in the sequence valve control mode.

[0147] In sequential valve control, the regulating valves open sequentially according to the pre-set flow characteristic curves of each valve. For example, in a 300MW unit manufactured by Harbin Turbine Works with six high-pressure regulating valves: the opening sequence is GV4 and GV5 open simultaneously → GV6 → GV3 → GV2 → GV1 open one by one, and the closing sequence is the opposite. Definition: In sequential valve control, there are 'a' steps from fully closed to fully open for all regulating valves; in the example above, 'a' is 5. Based on field tests, with all valves fully open, closing them sequentially until the final stage of full opening results in a number of inflection points, a-1. Define the inflection point number as m; the first valve to close has an inflection point number of m=1, and the last inflection point has an inflection point number of m=a-1. Calculate using the following formula:

[0148]

[0149] In the formula, P m Let P be the unit load corresponding to the m-th inflection point. e Unit load when valve is fully open

[0150] In the DCS, find the piecewise linear function used by each branch valve under the forward valve control mode. The important parameters in this function are the discrete comprehensive valve position command Yqi and its corresponding valve opening Xqi. Here, Yqi and Xqi are both normalized values.

[0151] In MATLAB, the polyfit and polyval functions are called to convert the actual high-frequency gate per-unit relative flow F. Rij％ Let y be the valve opening, and let x be the valve opening. Then, fit the valve to obtain the higher-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate;

[0152] Based on the relative flow y corresponding to the inflection point m And for each high-regulation valve, the higher-order continuous function y=f(x) and the piecewise linear function are used to calculate and obtain the correlation between the overall valve position and the relative flow rate; specifically:

[0153] 1. Determine the overall valve position command and relative flow rate for each inflection point, that is, find the overall valve position command for all inflection points from the piecewise linear function and match it with the calculated relative flow rate corresponding to the inflection point;

[0154] 2. If the integrated valve position is within the range of [0, integrated valve position command corresponding to the (a-1)th inflection point], then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i The value is then used to calculate the y-value of all high-adjustment valves that need to be opened within this range under the given integrated valve position. i The average value is multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0155] 3. If the integrated valve position is within the range of (the integrated valve position command corresponding to the (a-1)th inflection point, and the integrated valve position command corresponding to the (a-2)th inflection point), then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the (a-2)th inflection point - relative flow rate corresponding to the (a-1)th inflection point) + relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position; and so on.

[0156] 4. If the integrated valve position is within the range of (the integrated valve position command corresponding to the first inflection point, 1], then substitute this integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the first inflection point - relative flow rate corresponding to the second inflection point) + relative flow rate corresponding to the second inflection point to obtain the actual relative flow rate corresponding to the integrated valve position.

[0157] Subsequently, based on this comparison relationship, the overall valve position command or valve opening degree is corrected.

[0158] Application Examples

[0159] A method for correcting parameters of single valves and sequence valves based on the flow characteristics of DEH valves includes the following steps:

[0160] (I) Conducting on-site tests, taking a 300MW coal-fired unit as an example, where the turbine manufacturer and model are Dongfang Turbine Factory / N300-16.7 / 537 / 537, and the turbine valve and nozzle arrangement is as follows. Figure 1 There are 4 high-pressure doors in total. In the sequential valve mode, the opening sequence is GV1 and GV2 open simultaneously → GV3 → GV4.

[0161] Under test conditions, the load was basically stable at around 250MW when the valves were fully open. The unit was switched to DEH valve control mode, the primary frequency regulation control of the unit was cut off, the AGC control of the unit was cut off, the boiler-turbine coordination control was switched to manual, the automatic fuel supply control and the automatic oxygen supply control were cut off, and the automatic main steam temperature control, automatic feedwater control and automatic furnace pressure control were put into operation. A single step disturbance of 5% was performed on the high-pressure regulating valve from 100% to 0% and from 0% to 100%.

[0162] The collected values ​​are PT1 = [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).

[0163] P11=[9.9086 9.8544 9.8207 9.7987 9.7775 9.7569 9.732 9.7196 9.71969.7013 9.691 9.691 9.68 9.6661 9.6434 9.6075 9.5255 9.3966 9.2201 9.20469.3225; 10.2512 10.3149 10.353 10.375 10.4131 10.4131 10.4468 10.4468 10.446810.4468 10.4468 10.4321 10.4168 10.3809 10.3289 10.2249 10.0806 9.8572 9.57239.42739.3225].

[0164] TS1=[533.3653 533.1078 533.3224 533.3224 533.923 534.1805 534.9099535.6393 536.4116 537.2269 537.5272 538.1709 538.5142 538.9861 539.2436539.2865 539.2865 539.2865 539.501 539.7156539.9302; 529.847 526.8438 526.5863526.3718 526.3718 526.8438 527.616 528.3025 529.5038 531.1342 532.4213533.9659 535.5964 536.8836 538.2138 539.0291 539.501 539.9731 539.9731 539.9302 539.9302].

[0165] T11=[510.0246 510.0246 510.282 510.282 510.6253 511.226 512.0842512.7278 513.3286 513.8864 514.4442 514.7875 515.1307 515.1307 515.1307514.6158 513.4144 511.3119 507.879 506.5057 505.8191; 506.8061 503.7591503.4587 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).

[0166] The above data was collected using high-pitched gate No. 1 as an example. The data collected from the other three high-pitched gates are similar and will not be described in detail here.

[0167] When the sequence valve closes in the reverse direction of its opening, the unit load change is 253.86MW →

[0168] 237.35MW→187.85MW.

[0169] (ii) F can be obtained by calculation using the formula. R1j％=[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 0.1000.015]

[0170] [0.000], where j is (100%; 5%; 0), that is, starting from 100 and decreasing by 5 to 0, for a total of 21 numbers, and so on below. F R2j％ = [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].

[0171] F R3j％ =[1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.0001.000 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 0.993 0.984 0.962 0.926 0.860 0.756 0.586 0.360 0.094 0.032 0.000].

[0172] (iii) Correct the control parameters of a single valve.

[0173] F is calculated using the formula. R单阀j％ = [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].

[0174] The per-unit control parameters of the original single valve in the DCS are shown in Table 1.

[0175] Table 1

[0176] Integrated valve position 0 0.002 0.172 0.668 0.829 0.901 0.936 0.958 0.984 0.998 Valve opening -0.03 0.08 0.138 0.228 0.274 0.319 0.365 0.41 0.637 0.818

[0177] By fitting a function using MATLAB, for example, a 5th-order polynomial function, the functional relationship is obtained as follows:

[0178] y = -285.1282x 5 +488.5315x 4 -303.2191x 3 +75.8579x 2 -3.3862x+0.007972.

[0179] For example, when the valve opening is 0.228, the corrected composite valve position command should be 0.73; or when the composite valve position command is 0.829, the corrected valve opening should be 0.378; or after finding the function relationship, the entire broken line function can also be modified according to the user's customization.

[0180] Based on the above principles, the control parameters of a single valve can be modified as needed.

[0181] (iv) Correction of control parameters for the forward valve.

[0182] According to the experimental 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.

[0183] Find the per-unit parameters of the current forward valve control in the DCS, as shown in Table 2.

[0184] Table 2

[0185]

[0186]

[0187] In Table 2, the first inflection point used in practice is 0.899, and the second is 0.712. These are close to the inflection points measured in the field test, which are 0.9349 and 0.738 respectively. They also meet the overlap requirements and can be continued. This also conforms to the parameter usage of most power plants. Alternatively, the values ​​calculated in this paper can be used directly, that is, replacing 0.712 in the GV3 integrated valve position command column in Table 2 with 0.738, and replacing 0.899 in GV4 with 0.9349.

[0188] The discrete data from step (II) is fitted using MATLAB to obtain:

[0189] y1 = -323.0769x1 5 +550.7925x1 4 -339.4231x1 3 +84.6501x1 2-4.1412x1+0.0095559

[0190] y² = -301.0256x² 5 +510.1748x2 4 -315.1288x2 3 +79.1236x2 2 -3.753x2+0.0095332

[0191] y3 = -393.8462x3 5 +621.958x3 4 -354.9324x3 3 +80.9211x3 2 -2.862x3+0.0025245

[0192] y4 = -123.5897x4 5 +273.8345x4 4 -205.2558x4 3 +59.2105x4 2 -2.8227x4+0.0099773

[0193] Referring to the table above and the inflection point data, by substituting the opening degree of each valve into the above formula, the corresponding relative flow rate can be calculated. Then, a comparison table between the relative flow rate and the comprehensive valve position command under the currently used sequence valve parameters can be obtained, as shown in Table 3.

[0194] The specific calculation process is as follows:

[0195] 1. Determine the combined valve position command and relative flow rate at the two inflection points. That is, when the combined valve position command is 0.712, the relative flow rate is 0.738, and when the combined valve position command is 0.712, the relative flow rate is 0.9349.

[0196] 2. When the overall valve position is less than or equal to 0.712, taking the overall valve position command as 0.585 as an example, in the original parameter settings, the opening degree of GV1 and GV2 is 0.319. Substituting them into the above function relationship, we obtain two y values ​​of 0.9207 and 0.923 respectively. After averaging the two values, multiply by 0.738 to calculate the actual relative flow rate of 0.68 under this parameter. The other values ​​are calculated accordingly.

[0197] 3. When the overall valve position is greater than 0.712 and less than or equal to 0.899, taking the overall valve position of 0.835 as an example, the opening degree of GV3 in the original parameter setting is 0.206. Substituting into the above function relationship, the value of y is 0.718. Under this condition, GV1 and GV2 are fully open. Therefore, multiply the value 0.718 by (0.9349-0.738) and add 0.738 to calculate the actual relative flow rate of 0.879 under this parameter. The other values ​​are calculated accordingly.

[0198] 4. When the overall valve position is greater than 0.899, taking the overall valve position as 0.960 as an example, the opening degree of GV4 in the original parameter setting is 0.206. Substituting into the above function relationship, the value of y is 0.594. Under this condition, GV1, GV2, and GV3 are fully open. Therefore, multiply the value 0.594 by (1-0.9349) and add 0.9349 to calculate the actual relative flow rate under this parameter as 0.974. The other values ​​are calculated accordingly.

[0199] Table 3

[0200] Integrated valve position 0 0.585 0.689 0.712 0.835 0.890 0.899 0.960 0.984 0.994 1 relative flow 0 0.68 0.725 0.738 0.879 0.923 0.9349 0.974 0.993 0.998 1

[0201] Theoretically, after standardization, the combined valve position command and relative flow rate should have a relationship of y = x, x ∈ [0,1]. The theoretical function and the actual curve can be plotted on the same graph. Figure 2 .

[0202] For example, after comparison, it was found that the valve opening corresponding to the overall valve position command of 0.585 needs to be corrected. Table 3 shows that the calculated relative flow rate from the currently used parameters is 0.68. Theoretically, the relative flow rate and the overall valve position command should be directly proportional, so theoretically it should be 0.585, requiring correction. Table 2 shows that when the overall valve position command is 0.585, only high-pressure valves 1 and 2 are activated. Therefore, both high-pressure valves 1 and 2 need correction. Using the inverse function method, the valve opening of both high-pressure valves 1 and 2 should be corrected from 0.319 to 0.25. The correction method for other overall valve position commands corresponding to valve openings is similar.

[0203] Strictly speaking, all points can be corrected as long as they are not on the theoretical curve, i.e., the curve of direct proportionality. However, in practice, corrections are generally made according to the minimum range, i.e., only when there is a significant deviation from the point on the theoretical curve. Therefore, in the example, the point with the largest deviation is used for demonstration.

[0204] This concludes the method for correcting the control parameters of a sequence valve.

[0205] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics, characterized in that, Includes the following steps: Step (1), Data Acquisition: Switch the unit to DEH valve control mode, disconnect the unit's primary frequency regulation control, disconnect the unit's AGC control, switch the boiler-turbine coordination control to manual, disconnect the unit's automatic fuel supply, disconnect the automatic air supply oxygen supply, and activate the unit's automatic main steam temperature, automatic feedwater, and automatic furnace pressure. Perform a single step disturbance of 5% from 100% to 0% and from 0% to 100% for a single high-pressure valve. When a certain valve is activated, all other valves are opened. After the single high-pressure valve is activated, keep all valves fully open. Then, according to the 5% step, gradually close the valves in the reverse order of the sequence valve activation until the last stage valve is fully open. Record the unit load, main steam pressure before the turbine, regulating stage pressure, main steam temperature, and regulating stage temperature during the entire regulation process. Step (2), Flow characteristic curve calculation: Using the data obtained in step (1), the flow characteristic curve of each high-pressure valve is calculated according to the relative flow calculation formula; Step (3), parameter correction of each high-pressure regulating valve in single-valve control mode: Under single-valve control mode, calculate the actual single-valve per-unit relative flow rate; use the actual single-valve per-unit relative flow rate as y, and fit it with the corresponding valve opening as x to obtain the high-order continuous function y=f(x); find the piecewise linear function used by the single valve of the current unit in DCS; use the high-order continuous function y=f(x) to correct the comprehensive valve position command or valve opening. Step (4), parameter correction for each high-pressure regulating valve in the sequence valve control mode: Under the sequence valve control mode, there are a steps from fully closed to fully open for all regulating valves; when the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1, and the relative flow rate y corresponding to the inflection point is calculated. m ; In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening. By standardizing the relative flow rate of each high-regulation valve as y, and fitting the corresponding valve opening as x, we obtain the high-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate; Based on the relative flow y corresponding to the inflection point m And each high-key gate high-order continuous function y i =f i (x) A piecewise linear function is used to calculate and obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected. Step (2) specifically involves: With the unit at the opening degree j of high-pressure regulating valve i, j∈[0, 100%], the steam pressure ratio ε before and after the high-pressure regulating valve is... ij : The steam pressure is corrected based on the steam temperature before and after the high-pressure regulating valve, resulting in a steam pressure ratio ε'. ij ; Let F Rij =f(PT) ij P1 ij ,TS ij T1 ij ); Among them, PT ij The main steam pressure in front of the turbine is when the opening degree of the high-pressure regulating valve i is j, in MPa; P1 ij The regulating stage pressure is given when the opening degree of high-pressure regulating valve i is j, in MPa. TS ij The main steam temperature before the turbine is when the opening degree of high-pressure valve i is j, in °C; T1 ij The temperature after the regulating stage when the opening of the high-pressure regulating gate i is j, in °C; The relative flow rates within the test range were normalized to 0-100% per unit: F Rij％ =(F Rij -F Ri0 ) / (F Ri100 -F Ri0 ) Among them, F Rij％ The relative flow rate is when the opening of high-pressure gate i is j; F Ri0 The corrected steam pressure ratio for valve i when the valve opening is 0%; F Ri100 The corrected steam pressure ratio for valve i when the valve opening is 100%; Based on the obtained relative flow rate, plot the flow characteristic curve of valve i, the high-adjustment valve. In step (3), the actual per-unit relative flow rate of a single valve is calculated, specifically as follows: Where F R单阀j％ is the actual single-valve per-unit relative flow rate; i is the number of high-pressure regulating valves; j is the opening degree of the high-pressure regulating valve, j∈[0, 100%]; In the DCS, locate the piecewise linear function used by the current unit's single valve. In this function, Yn is the discrete integrated valve position command, and Xn is the valve opening corresponding to Yn. Then, normalize the actual single valve's per-unit relative flow rate F. R单阀j％ Let y be the valve opening, and let x be the valve opening, then fit the valve to obtain a higher-order continuous function y = f(x). Substituting Xn from the piecewise linear function into the fitted higher-order continuous function yields the corrected integrated valve position command Yn'; or using the inverse function method x = f -1 (y), by substituting Yn from the piecewise linear function into the solution of the higher-order continuous function, we obtain the corrected valve opening Xn'.

2. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics according to claim 1, characterized in that, In step (1), the recording sampling interval is 1 second.

3. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics according to claim 1, characterized in that, The specific method for step (4) is as follows: In the sequential valve control mode, there are a steps from all valves to fully closed to fully open. When the valves are fully open, the number of inflection points generated during the process of closing the valves in the closing sequence until the last stage of full opening is a-1. The inflection point number corresponding to the first closed valve is m=1, the inflection point number corresponding to the second closed valve is m=2, and so on, with the last inflection point number being m=a-1. Calculate the relative flow rate y corresponding to the inflection point m ; In the formula, P m Let P be the unit load corresponding to the m-th inflection point. e Unit load when valve is fully open In the DCS, find the piecewise linear function used by each branch valve under the sequential valve control mode. In this function, Yqi is the discrete integrated valve position command and Xqi is the corresponding valve opening. The actual high-frequency gate per-unit relative flow F Rij％ Let y be the valve opening, and let x be the valve opening. Then, fit the valve to obtain the higher-order continuous function y for each high-regulation valve. i =f i (x); i is the i-th high-key gate; Based on the relative flow y corresponding to the inflection point m And each high-key gate high-order continuous function y i =f i (x) A piecewise linear function is used to calculate and obtain the relationship between the overall valve position and the relative flow rate; specifically: (1) Determine the comprehensive valve position command and relative flow rate for each inflection point, that is, find the comprehensive valve position command for all inflection points from the piecewise linear function and match it with the calculated relative flow rate corresponding to the inflection point; (2) If the integrated valve position is within the range of [0, integrated valve position command corresponding to the (a-1)th inflection point], then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment gate that needs to be opened within this range to obtain the corresponding y. i The value is then used to calculate the y-value of all high-adjustment valves that need to be opened within this range under the given integrated valve position. i The average value is multiplied by the relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position. (3) If the integrated valve position is within the range of (the integrated valve position command corresponding to the (a-1)th inflection point, the integrated valve position command corresponding to the (a-2)th inflection point), then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment gate that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the (a-2)th inflection point - relative flow rate corresponding to the (a-1)th inflection point) + relative flow rate corresponding to the (a-1)th inflection point to obtain the actual relative flow rate corresponding to the integrated valve position; and so on. (4) If the integrated valve position is within the range of (the integrated valve position command corresponding to the first inflection point, 1], then substitute the integrated valve position as x into the high-order continuous function of each high-adjustment valve that needs to be opened within this range to obtain the corresponding y. i Value; excluding high-pressure doors that are already fully open; then calculate the y-value of all high-pressure doors that need to be opened within this range under this overall valve position. i The average value is multiplied by (relative flow rate corresponding to the first inflection point - relative flow rate corresponding to the second inflection point) + relative flow rate corresponding to the second inflection point to obtain the actual relative flow rate corresponding to the integrated valve position. Subsequently, based on this comparison relationship, the overall valve position command or valve opening degree is corrected.

4. The method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics according to claim 3, characterized in that, Corrections are made for the points in the control relationship that deviate the most from the theoretical curve.

5. A system for correcting single valve and sequence valve parameters based on DEH valve flow characteristics, employing the method for correcting single valve and sequence valve parameters based on DEH valve flow characteristics as described in any one of claims 1 to 2, characterized in that, include: The data acquisition module is used to collect data during the test, including unit load, main steam pressure before the turbine, regulating stage pressure, main steam flow rate, feedwater flow rate, main steam desuperheating water flow rate, main steam temperature, reheat steam temperature, steam drum pressure, and total turbine energy flow. The data processing module is used to calculate the flow characteristic curve of each high-pressure valve based on the data collected by the data acquisition module and the relative flow calculation formula. The parameter correction module for each high-pressure valve in the single-valve control mode is used to calculate the actual single-valve per-unit relative flow rate; the actual single-valve per-unit relative flow rate is y, and the corresponding valve opening is x, to obtain a high-order continuous function y=f(x); the piecewise linear function used by the single valve of the current unit is found in the DCS; the high-order continuous function y=f(x) is used to correct the integrated valve position command or valve opening. The parameter correction module for each high-pressure valve in the sequence valve control method is used to calculate the relative flow rate y corresponding to the inflection point. m In the DCS, find the piecewise linear function used by each branch control valve under sequential valve control mode. In this function, Yqi is the discrete comprehensive valve position command, and Xqi is the corresponding valve opening. Standardize the actual relative flow rate of each high-pressure control valve to y, and fit it with the corresponding valve opening to x to obtain the high-order continuous function y for each high-pressure control valve. i =f i (x); i is the i-th high-pitched gate; based on the relative flow y corresponding to the inflection point. m And each high-key gate high-order continuous function y i =f i (x) A piecewise linear function is used to calculate and obtain the correlation between the overall valve position and the relative flow rate; based on this correlation, the overall valve position command or valve opening is corrected.

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