A method and system for coupling feedforward valve position control to thermal power AGC

Abstract

This invention discloses a method and system for coupled feedforward valve position control in thermal power AGC (Automatic Guided Vehicle) systems, belonging to the field of thermal power AGC control technology. Under the AGC activation state of the thermal power unit, this method collects operating data from the DCS (Distributed Control System) main control regulating loop. The model input data is then input into a pressure-load valve position coupled feedforward model. Through pressure-load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression, the method generates a valve-positioned main steam pressure feedforward quantity and an equivalent valve position channel quantity corresponding to load correction. These two quantities are then connected to the DCS main control integrated valve position summation loop, forming the main control integrated valve position control output quantity together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity. This invention addresses the problems of initial adjustment lag in AGC load response and insufficient valve position action accuracy under small deviation conditions, improving the timeliness of integrated valve position adjustment and the stability of AGC response.

Description

Technical Field

[0001] This invention belongs to the field of thermal power AGC control technology, and particularly relates to a method and system for controlling the position of a coupled feedforward valve in thermal power AGC. Background Technology

[0002] AGC control of thermal power units typically receives load commands from the grid dispatching side through the main control and regulation loop of the DCS (Distributed Control System), and adjusts the unit output by combining these with operating signals such as actual unit load, main steam pressure, and valve position feedback. Existing main control and regulation loops generally rely on existing coordinated control logic, load correction loops, main steam pressure deviation regulation, and related feedforward compensation to achieve load tracking.

[0003] During the operation of AGC, after the load command on the grid dispatch side changes, the actual generating load of the unit needs to cross the AGC response dead zone along the regulation direction within a specified time. For some thermal power units, the existing main control regulation loop has problems such as insufficient timeliness in the formation of regulation and insufficient matching between valve position action and load response in the initial stage of load command change, which can easily lead to a lag in the actual generating load response, resulting in a low AGC response time index.

[0004] When the deviation between the target load command and the load command after rate processing is small, the existing load correction method may suffer from inaccurate correction or ineffective disturbances, affecting the stability of the main control control loop under small deviation conditions. Therefore, it is necessary to improve the main control valve position control method of thermal power units under AGC conditions to improve the timeliness of adjustment in the initial stage of load response and the accuracy of operation under small deviation conditions. Summary of the Invention

[0005] The technical problem this invention aims to solve is to address the issues of insufficient timeliness in the initial response of the main control regulating loop to changes in AGC load commands during the existing AGC control process of thermal power units, excessively long time for the actual power generation load to cross the AGC response dead zone, and insufficient accuracy of load correction under small deviation conditions. This invention provides a thermal power AGC coupled feedforward valve position control method and system to improve the timeliness of AGC adjustment in the initial stage of load response and the stability of valve position action under small deviation conditions, while retaining the original DCS main control regulating loop control structure.

[0006] To address the aforementioned technical problems, this invention provides a method for controlling the position of a feedforward valve in a thermal power plant's AGC coupling system, comprising the following steps:

[0007] S1: When the thermal power unit is in AGC mode, collect the operating data of the DCS main control regulation loop. The operating data includes model input data and the basic integrated valve position of the main control unit. The model input data includes AGC target load command, rate-after-load command, load setpoint, actual power generation load, actual main steam pressure, main steam pressure setpoint, and integrated valve position feedback.

[0008] S2: Input the model input data into the pressure load valve position coupled feedforward model. The pressure load valve position coupled feedforward model performs pressure load quotient calculation, operating condition interval identification, valve position conversion and small deviation suppression.

[0009] S3: Pressure load quotient calculation: Generates the main steam pressure quotient feedforward based on the quotient relationship between the AGC adjustment direction, the actual main steam pressure value, and the load setpoint; Operating condition interval identification: Determines the current operating condition interval based on the load setpoint, the actual main steam pressure value, and the integrated valve position feedback. The current operating condition interval is the load main steam pressure valve position operating condition interval; Valve position conversion: Converts the main steam pressure quotient feedforward into a valve position-based main steam pressure feedforward based on the model parameter group corresponding to the current operating condition interval; Small deviation suppression: Generates the equivalent valve position channel quantity corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and suppresses the equivalent valve position channel quantity corresponding to the load correction when the deviation is within the preset small deviation interval;

[0010] S4: The valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction are connected to the DCS main control integrated valve position summation link, and together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity, they form the main control integrated valve position control output quantity. The main steam pressure deviation valve position adjustment quantity is formed by the deviation between the main steam pressure set value and the actual main steam pressure value through PID regulation.

[0011] In a preferred embodiment, inputting the model input data into the pressure load valve position coupled feedforward model includes:

[0012] The pressure load valve position coupling feedforward model is executed through the additional feedforward function block in the DCS main control regulation loop.

[0013] Add a feedforward function block to the signal corresponding to the model input data;

[0014] The additional feedforward function block outputs the valve position main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction, according to the control cycle of the DCS main control regulation loop.

[0015] In a preferred embodiment, the pressure load quotient calculation includes:

[0016] The direction of AGC adjustment is determined based on the relationship between the target load command and the actual power generation load.

[0017] Based on the AGC adjustment direction, the actual value of the main steam pressure, the setpoint of the main steam pressure, and the load setpoint, the feedforward amount of the main steam pressure quotient is generated according to the following model relationship:

[0018] ;

[0019] Directional coupling pressure margin limiting factor Determined according to the following relationship:

[0020] ;

[0021] In the formula, For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. For the first The direction of AGC adjustment in the control cycle of each DCS main control adjustment loop. For the first The actual value of the main steam pressure during the control cycle of the DCS main control regulating loop. For the first The main steam pressure setpoint for the control cycle of the DCS main control regulating loop. For the first The load setpoint of the control cycle of each DCS main control regulation loop. A load correction constant with the same dimensions as the load setpoint. A pressure correction constant with the same dimensions as the main steam pressure setpoint, and , , For the first The control cycle of each DCS main control regulation loop corresponds to the current operating condition interval number. The feedforward coefficient is the quotient value corresponding to the current operating condition interval. This is the main steam pressure margin correction factor corresponding to the current operating condition range. Adjust the lower limit of the pressure margin corresponding to the current operating condition range. Adjust the upper limit of the pressure margin corresponding to the current operating condition range, and satisfy the following conditions: ;

[0022] When the AGC target load command is greater than the actual power generation load Values When the AGC target load command is less than the actual power generation load, Values When the AGC target load command equals the actual power generation load, Values .

[0023] In a preferred embodiment, the operating condition range identification includes:

[0024] Based on historical AGC operation samples, multiple load main steam pressure valve position operating condition ranges are established. Each load main steam pressure valve position operating condition range is jointly defined by the load set value range, the actual main steam pressure value range, and the comprehensive valve position feedback range.

[0025] Based on the load setpoint, actual main steam pressure, and integrated valve position feedback within the control cycle of the current DCS main control regulating loop, the current operating condition range is determined from multiple load main steam pressure valve position operating condition ranges;

[0026] When the current operating point, formed by the load setpoint, the actual main steam pressure, and the integrated valve position feedback, is located within the boundary of two adjacent load main steam pressure valve position operating condition intervals, the model parameters of the two adjacent load main steam pressure valve position operating condition intervals are weighted and transitioned according to the relative position of the current operating point and the two adjacent load main steam pressure valve position operating condition intervals, and the weighted and transitioned model parameters are used as the model parameters of the current operating condition interval.

[0027] In a preferred embodiment, the valve position switching includes:

[0028] The main steam pressure quotient feedforward is converted into a valve position-based main steam pressure feedforward according to the dynamic valve position conversion relationship. The valve position-based main steam pressure feedforward is then used to access the DCS main control integrated valve position summation link.

[0029] The dynamic valve position switching relationship is as follows:

[0030] ;

[0031] In the formula, For the first The valve position-based main steam pressure feedforward of the control cycle of each DCS main control regulating loop. For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. This is the feedforward amount of the main steam pressure quotient for the control cycle of the previous DCS main control regulating loop. This is a comprehensive valve position feedback buffer for the control cycle of the previously completed DCS main control regulation loop. To further buffer the control cycle of the completed DCS main control regulation loop, the integrated valve position feedback is used. This represents the valve position transition slope coefficient corresponding to the current operating condition range. This is the valve position switching bias coefficient corresponding to the current operating condition range. This is the feedforward variation compensation coefficient corresponding to the current operating condition range. This is the valve position feedback change compensation coefficient corresponding to the current operating condition range. For the first The feedforward enable coefficient of the control cycle of the main control regulation loop of the DCS machine;

[0032] When the feedforward enable condition is met, When the feedforward enable condition is not met, The feedforward enable conditions are: AGC is in a valid state, the model input data is valid, and the AGC adjustment direction is not zero.

[0033] The valve position switching slope coefficient and feedforward change compensation coefficient are used to convert the main steam pressure quotient feedforward amount and the single-cycle change amount of the main steam pressure quotient feedforward amount into the valve position channel equivalent amount with the same dimensions as the input quantity of the DCS main control integrated valve position summation link; the valve position switching bias coefficient is used to compensate for the valve position switching deviation under the current operating condition range; the valve position feedback change compensation coefficient is used to correct the valve position-based main steam pressure feedforward amount according to the integrated valve position feedback change amount between two adjacent completed control cycles.

[0034] When the feedforward enable condition is met for the first time, the difference term is initialized, so that... And make .

[0035] In a preferred embodiment, before the valve position conversion converts the main steam pressure quotient feedforward into a valve-positioned main steam pressure feedforward based on the model parameters of the current operating range, it further includes determining or updating the model parameter group corresponding to the current operating range. Determining or updating the model parameter group corresponding to the current operating range includes:

[0036] Based on historical AGC operation samples, a set of model parameters is determined for each load main steam pressure valve position operating condition range. The set of model parameters includes quotient feedforward coefficient, main steam pressure margin correction coefficient, pressure margin correction lower limit, pressure margin correction upper limit, valve position transition slope coefficient, valve position transition bias coefficient, feedforward change compensation coefficient, and valve position feedback change compensation coefficient.

[0037] When determining the model parameter set, the AGC response time, main steam pressure fluctuation, single-cycle change of integrated valve position, load overshoot, and the deviation between the valve-positioned main steam pressure feedforward and the integrated valve position feedback change are used as parameter evaluation quantities.

[0038] Before the pressure load valve position coupling feedforward model is put into use, the model parameter set is initially determined based on historical AGC operation samples;

[0039] After the pressure load valve position coupling feedforward model is put into use, the model parameter group is rolled over based on the newly added AGC operation samples.

[0040] In a preferred embodiment, before determining the model parameters corresponding to each load main steam pressure valve position operating condition range based on historical AGC operating samples, the historical AGC operating samples are screened, including:

[0041] Remove operating samples that are not in the AGC (Automatic Guided Vehicle) state;

[0042] Remove any operating samples with invalid data from the following: actual main steam pressure, set main steam pressure, load set value, actual power generation load, or integrated valve position feedback.

[0043] The start time of the response sample segment is taken as the moment when the AGC target load command changes, and the end time of the response sample segment is taken as the moment when the actual power generation load crosses the AGC response dead zone and a preset holding time has elapsed, thus obtaining the response time-related sample.

[0044] Calculate the AGC response time, main steam pressure fluctuation, single-cycle change of integrated valve position, and load overshoot based on relevant response time samples.

[0045] Based on the load main steam pressure valve position operating condition range to which the response time-related samples belong, the response time-related samples are assigned to the corresponding load main steam pressure valve position operating condition range.

[0046] In a preferred embodiment, the small deviation suppression includes:

[0047] The equivalent valve position channel quantity corresponding to the load correction is generated based on the deviation between the AGC target load command and the rate-based load command.

[0048] The first deviation threshold, the second deviation threshold, and the preset load correction upper limit are determined based on the current operating condition range, and the first deviation threshold is less than the second deviation threshold.

[0049] When the absolute value of the deviation is not greater than the first deviation threshold, the equivalent value of the valve position channel corresponding to the load correction is set to zero.

[0050] When the absolute value of the deviation is greater than the first deviation threshold and less than the second deviation threshold, the equivalent quantity of the valve position channel corresponding to the load correction is determined according to the monotonic piecewise mapping relationship corresponding to the current working condition interval. The direction of the equivalent quantity of the valve position channel corresponding to the load correction is determined by the sign of the deviation.

[0051] When the absolute value of the deviation is not less than the second deviation threshold, the absolute value of the equivalent quantity of the valve position channel corresponding to the load correction is limited to the preset load correction upper limit.

[0052] In a preferred embodiment, the step of connecting the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction to the DCS main control integrated valve position summation stage includes:

[0053] The original main steam pressure deviation PID branch in the DCS main control regulation loop is retained;

[0054] The valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction are used as additional feedforward quantities and input into the DCS main control integrated valve position summation link. The additional feedforward quantity does not replace the output of the original main steam pressure deviation PID branch.

[0055] Within the control cycle of each DCS main control regulation loop, the computer main control comprehensive valve position pre-output is calculated based on the main control basic comprehensive valve position quantity, the main steam pressure deviation valve position adjustment quantity, the valve position feedforward quantity of the main steam pressure, and the equivalent quantity of the valve position channel corresponding to the load correction.

[0056] When the feedforward enabling condition is not met, the additional feedforward quantity is locked out, and the original main steam pressure deviation PID branch participates in the main control integrated valve position control output.

[0057] When the pre-output quantity of the main control integrated valve position exceeds the preset allowable range of the integrated valve position, the equivalent quantity of the valve position channel corresponding to the valve position feedforward quantity and the load correction is subjected to grouped amplitude limiting processing according to the same amplitude limiting ratio that makes the pre-output quantity of the main control integrated valve position fall into the preset allowable range of the integrated valve position, and the basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity of the main control are not changed.

[0058] The valve position feedforward quantity of the main steam pressure after the lockout processing or group amplitude limiting processing, the equivalent quantity of the valve position channel corresponding to the load correction, together with the main engine control basic comprehensive valve position quantity and the main steam pressure deviation valve position adjustment quantity, form the main engine control comprehensive valve position control output quantity.

[0059] This invention also provides a thermal power AGC coupled feedforward valve position control system, applied to the aforementioned thermal power AGC coupled feedforward valve position control method, comprising:

[0060] The data acquisition module is used to collect the operating data of the DCS main control regulation loop when the AGC of the thermal power unit is in operation. The operating data includes model input data and the basic comprehensive valve position of the main control unit. The model input data includes AGC target load command, rate-after-load command, load setpoint, actual power generation load, actual value of main steam pressure, setpoint of main steam pressure and comprehensive valve position feedback.

[0061] The quotient calculation module is used to generate the main steam pressure quotient feedforward based on the quotient relationship between the AGC adjustment direction, the actual value of the main steam pressure and the load set value, and to correct the main steam pressure quotient feedforward based on the directional coupling pressure margin limiting factor.

[0062] The operating condition identification module is used to determine the current operating condition range based on the load setpoint, the actual main steam pressure, and the comprehensive valve position feedback. The current operating condition range is the load, main steam pressure, and valve position operating condition range.

[0063] The valve position conversion module is used to convert the main steam pressure quotient feedforward into a valve-positioned main steam pressure feedforward based on the model parameter group corresponding to the current operating condition range, and to control the output of the valve-positioned main steam pressure feedforward according to the feedforward enable coefficient.

[0064] The small deviation suppression module is used to generate the equivalent amount of the valve position channel corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and to suppress the equivalent amount of the valve position channel corresponding to the load correction when the deviation is within the preset small deviation range.

[0065] The valve position output module is used to input the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction into the DCS main control integrated valve position summation link, and together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity, it forms the main control integrated valve position control output quantity. The main steam pressure deviation valve position adjustment quantity is formed by the deviation between the main steam pressure set value and the actual main steam pressure value through PID regulation.

[0066] The quotient calculation module, operating condition identification module, valve position conversion module, and small deviation suppression module together constitute the pressure load valve position coupling feedforward model.

[0067] Compared with existing technologies, the beneficial effects of this invention are as follows: When the AGC (Automatic Guided Control) is engaged in a thermal power unit, this invention collects operating data from the DCS (Distributed Control System) main control circuit. It then generates a valve-positioned main steam pressure feedforward quantity and a corresponding equivalent quantity for the valve position channel based on a pressure-load-valve-position coupling feedforward model. These two quantities are then input into the DCS main control integrated valve position summation loop. This allows for the introduction of an additional feedforward adjustment quantity matching the current operating state into the integrated valve position control output while retaining the original main control logic, thereby improving the timeliness of valve position adjustment in the initial stages of load command changes.

[0068] This invention establishes a continuous processing flow through pressure load quotient calculation, operating condition range identification, valve position switching, and small deviation suppression. This allows additional feedforward and load correction quantities to participate in the main control's integrated valve position control output as equivalent quantities in the valve position channel. This method reduces ineffective correction actions under small deviation conditions, improving the accuracy of the main control's regulating loop and the stability of AGC response. Attached Figure Description

[0069] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1This is a flowchart of the method in an embodiment of the present invention; Figure 2 This is a schematic diagram of the modular structure of the system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the internal structure of the pressure load valve position coupling feedforward model in an embodiment of the present invention; Figure 4 This is a schematic diagram of the original DCS main control and regulation circuit; Figure 5 This is a schematic diagram of the connection relationship of the DCS main control regulation loop after adding the pressure load valve position coupling feedforward model in an embodiment of the present invention. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0071] In this embodiment, combined with Figure 3 , Figure 4 and Figure 5 This paper describes the coupling feedforward valve position control method for AGC in thermal power plants. Figure 3 The internal structure of the pressure-load valve-position coupling feedforward model is shown. This model includes a quotient calculation module, a working condition identification module, a valve position conversion module, and a small deviation suppression module. The quotient calculation module generates the main steam pressure quotient feedforward quantity based on the AGC adjustment direction and the quotient relationship between the actual main steam pressure and the load setpoint. The working condition identification module determines the current working condition range based on the load setpoint, the actual main steam pressure, and the comprehensive valve position feedback. The valve position conversion module converts the main steam pressure quotient feedforward quantity into a valve-positioned main steam pressure feedforward quantity based on the model parameter set corresponding to the current working condition range. The small deviation suppression module generates the valve position channel equivalent quantity corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command. Therefore, Figure 3 This corresponds to the explanation of the data flow and output relationship between the various processing modules within the pressure load valve position coupling feedforward model.

[0072] Figure 4 The basic structure of the original DCS main control and regulation loop is shown. The original DCS main control and regulation loop receives inputs such as load command setpoint, load correction, frequency regulation load, deviation between the main steam pressure setpoint and the actual main steam pressure, and unit load selection signal, and forms a comprehensive valve position through a summing stage and a PID control stage. Figure 4This describes the basic control structure that already existed in the original DCS main control regulation loop before the implementation of this invention, including the main steam pressure deviation PID branch, the main control basic integrated valve position quantity, and the DCS main control integrated valve position summation link.

[0073] Figure 5 This illustrates the connection relationships after adding a pressure load valve position coupling feedforward model to the original DCS main control regulation loop. Figure 4 compared to, Figure 5 The newly added pressure-load valve position coupling feedforward model generates valve position-based main steam pressure feedforward and load correction equivalent valve position channel quantity based on the model input data, and inputs the above two quantities as additional feedforward quantities into the DCS main control integrated valve position summation link. Figure 5 This also shows that the original main steam pressure deviation PID branch and the integrated valve position quantity of the main engine control system still participate in the formation of the integrated valve position control output of the main engine control system. Therefore, Figure 5 This invention is intended to illustrate that it does not replace the original DCS main control regulation loop, but rather, while retaining the original control structure, it connects the additional feedforward quantity output by the pressure load valve position coupling feedforward model to the comprehensive valve position summation loop.

[0074] The above Figure 3 , Figure 4 and Figure 5 The hardware / logic foundation and signal access methods of this embodiment are explained from the perspectives of the model's internal structure, the original DCS main control and regulation circuit, and the modified connection relationships. Combined with... Figure 1 The specific process of the thermal power AGC coupled feedforward valve position control method in this embodiment is further explained.

[0075] like Figure 1 As shown, one embodiment of the present invention provides a coupled feedforward valve position control method for thermal power AGC, which is applied to the main control and regulation loop of the DCS of a thermal power unit. This method, while retaining the original DCS main control and regulation loop, introduces a pressure-load valve position coupled feedforward model. Through pressure-load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression, it generates the valve position-based main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction. These two quantities are then connected to the DCS main control integrated valve position summation loop.

[0076] The method described in this embodiment includes the following steps.

[0077] S1: Collect operating data of the DCS main control and regulation circuit;

[0078] In this embodiment, S1 is used to collect operating data from the DCS main control control loop for subsequent feedforward calculations and integrated valve position output when the thermal power unit's AGC is engaged. The thermal power unit's AGC control receives AGC control information from the dispatching side via the RTU and sends it to the DCS. The DCS simultaneously feeds back the unit's AGC engagement / disengagement status to the dispatching side. When the unit's coordinated control system (CCS) is operating normally and stably and the AGC engagement status is valid, the DCS main control control loop enters the data acquisition process of this embodiment.

[0079] Specifically, within each control cycle of the DCS main control regulation loop, the data acquisition module collects operational data from the DCS real-time database, the main control logic page, or the corresponding signal channel. The operational data includes model input data and the basic integrated valve position values ​​of the main control system. Model input data includes AGC target load commands, rate-based load commands, load setpoints, actual power generation load, actual main steam pressure, main steam pressure setpoints, and integrated valve position feedback.

[0080] Among them, the AGC target load instruction is the target load signal after the dispatching side AGC load requirement enters the DCS; the rate-limited load instruction is the load instruction after the AGC target load instruction has been processed by the DCS rate limit; the load setpoint is the set value currently used for load control in the DCS main control regulating loop; the actual power generation load is the generator active power feedback value; the actual value of the main steam pressure is the feedback value of the main steam pressure measuring point; the main steam pressure setpoint is the set pressure used for pressure deviation calculation in the DCS main control regulating loop; and the integrated valve position feedback is the integrated opening feedback of the turbine regulating valve or the feedback value in the DCS representing the integrated valve position.

[0081] The basic integrated valve position quantity of the main engine control system is the basic output quantity of the integrated valve position formed by the original DCS main engine control regulation loop before the addition of the feedforward quantity in this embodiment. The original DCS main engine control regulation loop includes control logic such as load correction, frequency regulation load, deviation between main steam setpoint and actual value, PID regulation, SUM summation, and integrated valve position output. The purpose of collecting the basic integrated valve position quantity of the main engine control system in this embodiment is to retain the basic control function of the original main engine control regulation loop in subsequent steps.

[0082] To ensure that subsequent pressure load quotient calculations, operating condition range identification, valve position switching, and small deviation suppression use data from the same operating state, the data acquisition module synchronously samples the model input data and the integrated valve position quantities of the main control system within the control cycle of the same DCS main control control loop, and assigns the same control cycle identifier to the collected data. Load data uses a unified load dimension, pressure data uses a unified pressure dimension, and valve position data uses a unified valve position engineering quantity or percentage opening within the DCS. When there are differences in engineering quantity calibration between different signal channels, conversion is performed according to the DCS engineering quantity calibration relationship.

[0083] After data acquisition, the data acquisition module performs a validity check on the model input data. The validity check includes determining whether there are communication interruptions, dead pixels, over-range operations, or abnormal holding conditions in the AGC target load command, rate-followed load command, load setpoint, actual power generation load, actual main steam pressure, main steam pressure setpoint, and integrated valve position feedback. The model input data after validity checks is used to input the pressure-load-valve-position coupled feedforward model. The integrated valve position quantity of the main generator control system is then used, together with the valve-positioned main steam pressure feedforward quantity, the equivalent quantity of the valve position channel corresponding to the load correction, and the main steam pressure deviation valve position adjustment quantity, to form the integrated valve position control output quantity of the main generator control system.

[0084] S2: Input the model input data into the pressure load valve position coupled feedforward model;

[0085] In this embodiment, S2 is used to send the model input data obtained in S1 into the pressure-load valve position coupled feedforward model. This model then generates two output quantities according to the control cycle of the DCS main control control loop: a valve-positioned main steam pressure feedforward quantity and a valve position channel equivalent quantity corresponding to load correction. Specifically, a feedforward branch formed by the quotient of the main steam pressure and the load setpoint is added to the original main control control loop. The feedforward is corrected using a valve position conversion function. Simultaneously, the linear function of the deviation between the target load command and the rate-based load command is modified in the load correction loop. This embodiment unifies the above control logic into a pressure-load valve position coupled feedforward model so that it can be executed as additional feedforward logic in the DCS main control control loop.

[0086] The internal structure of the pressure load valve position coupled feedforward model is as follows: Figure 3 As shown, the pressure load valve position coupling feedforward model includes a quotient calculation module, a working condition identification module, a valve position conversion module, and a small deviation suppression module.

[0087] Specifically, the pressure load valve position coupling feedforward model is executed through an additional feedforward function block in the DCS main control control loop. This additional feedforward function block can be formed by combining analog quantity calculation blocks, multiplication blocks, division blocks, summation blocks, limiting blocks, function conversion blocks, delay buffer blocks, and enable judgment blocks in the DCS. Specifically, the modified main control control loop already shows the logic structures related to the newly added feedforward branch, such as main steam pressure, DIV, MUL, analog quantity coefficient A, and SUM. Therefore, this type of additional feedforward logic can be implemented in the original DCS main control control loop through function blocks.

[0088] In terms of input connectivity, the additional feedforward function block receives signals corresponding to the model input data. Specifically, this includes: AGC target load command, rate-following load command, load setpoint, actual power generation load, actual main steam pressure, main steam pressure setpoint, and integrated valve position feedback. Among these, the AGC target load command and actual power generation load are used to determine the AGC adjustment direction; the actual main steam pressure, main steam pressure setpoint, and load setpoint are used to perform pressure-load quotient calculation; the load setpoint, actual main steam pressure, and integrated valve position feedback are used to perform operating condition range identification; the main steam pressure quotient feedforward and integrated valve position feedback are used to perform valve position switching; and the AGC target load command and rate-following load command are used to perform small deviation suppression.

[0089] At the internal processing level of the model, the pressure-load-valve-position coupled feedforward model includes four processing stages: pressure-load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression. Pressure-load quotient calculation generates a main steam pressure quotient feedforward quantity based on the quotient relationship between the actual main steam pressure and the load setpoint. Operating condition interval identification determines the current operating condition interval based on the load setpoint, the actual main steam pressure, and the integrated valve position feedback. Valve position conversion converts the main steam pressure quotient feedforward quantity into a valve-positioned main steam pressure feedforward quantity based on the model parameter set corresponding to the current operating condition interval. Small deviation suppression generates the equivalent quantity of the valve position channel corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and suppresses this equivalent quantity of the valve position channel when the deviation is within a preset small deviation interval.

[0090] During DCS execution, the additional feedforward function block operates cyclically according to the control cycle of the DCS main control regulation loop. Within each control cycle, the additional feedforward function block first reads the model input data for the current cycle, then sequentially completes the pressure-load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression. Finally, it outputs the valve-positioned main steam pressure feedforward and the equivalent valve position channel quantity corresponding to the load correction. The valve-positioned main steam pressure feedforward represents the valve position channel feedforward obtained from the conversion between the main steam pressure and the load setpoint; the equivalent valve position channel quantity corresponding to the load correction represents the valve position channel correction obtained from the conversion between the target load command and the rate-followed load command.

[0091] Regarding the output connection, the valve-positioned main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction output of the additional feedforward function block serve as two additional feedforward quantities connected to the DCS main control integrated valve position summation stage in subsequent S4. These two quantities do not replace the basic control logic in the original DCS main control regulation loop, but rather participate as additional quantities in the formation of the main control integrated valve position control output quantity together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity.

[0092] S3: Performs pressure load quotient calculation, operating condition range identification, valve position switching, and small deviation suppression;

[0093] In this embodiment, S3 is used to process the model input data input by S2 within the pressure-load valve-position coupling feedforward model, and generate the valve-positioned main steam pressure feedforward and the equivalent valve-position channel quantity corresponding to the load correction. The pressure-load valve-position coupling feedforward model operates according to the control cycle of the DCS main control regulation loop, and sequentially executes pressure-load quotient calculation, operating condition interval identification, valve-position conversion, and small deviation suppression within each control cycle. There is a clear data connection relationship between the above four processing links: pressure-load quotient calculation generates the main steam pressure quotient feedforward; operating condition interval identification determines the current operating condition interval and the model parameter set corresponding to the current operating condition interval; valve-position conversion converts the main steam pressure quotient feedforward into the valve-positioned main steam pressure feedforward based on the model parameter set; and small deviation suppression generates the equivalent valve-position channel quantity corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command.

[0094] In the calculation of the pressure load quotient, the AGC adjustment direction is first determined based on the relationship between the AGC target load command and the actual power generation load. Specifically, the difference between the AGC target load command and the actual power generation load is defined as the load deviation, and both the preset upward dead zone threshold and the preset downward dead zone threshold are positive numbers. When the load deviation is greater than the preset upward dead zone threshold, the AGC adjustment direction is the load increase direction. When the load deviation is less than the negative of the preset downward dead zone threshold, the AGC adjustment direction is the load reduction direction. When the load deviation is between the negative of the preset downward dead zone threshold and the preset upward dead zone threshold, the AGC adjustment direction is set to no adjustment direction. By using the above-mentioned dead zone determination, the frequent switching of AGC adjustment direction caused by fluctuations in actual power generation load measurements can be reduced.

[0095] After determining the AGC adjustment direction, a main steam pressure quotient feedforward is generated based on the AGC adjustment direction, the actual main steam pressure value, the main steam pressure setpoint, and the load setpoint. The main steam pressure quotient feedforward is used to characterize the strength of the feedforward effect of the actual main steam pressure value relative to the current load demand. In one embodiment, the main steam pressure quotient feedforward is determined according to the following model relationship:

[0096] ;

[0097] Directional coupling pressure margin limiting factor Determined according to the following relationship:

[0098] ;

[0099] In the formula, For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. For the first The direction of AGC adjustment in the control cycle of each DCS main control adjustment loop. For the first The actual value of the main steam pressure during the control cycle of the DCS main control regulating loop. For the first The main steam pressure setpoint for the control cycle of the DCS main control regulating loop. For the first The load setpoint of the control cycle of each DCS main control regulation loop. A load correction constant with the same dimensions as the load setpoint. A pressure correction constant with the same dimensions as the main steam pressure setpoint, and , By setting and This can avoid the problem of an excessively small denominator when the load setpoint or main steam pressure setpoint is involved in division operations.

[0100] For the first The control cycle of each DCS main control regulation loop corresponds to the current operating condition interval number. This is the quotient feedforward coefficient corresponding to the current operating condition range, used to convert the quotient of the actual value of the main steam pressure and the load setpoint into the quotient feedforward amount of the main steam pressure. This is the main steam pressure margin correction coefficient corresponding to the current operating condition range, used to adjust the influence of the deviation of the actual main steam pressure value from the main steam pressure set value on the feedforward amplitude. Adjust the lower limit of the pressure margin corresponding to the current operating condition range. Adjust the upper limit of the pressure margin corresponding to the current operating condition range, and satisfy the following conditions: Directional coupling pressure margin limiting factor A positive dimensionless correction factor is used to correct the value without changing the value of the correction factor. Under the premise of the determined adjustment direction, the amplitude of the feedforward amount of the main steam pressure quotient is bounded to avoid abnormal amplification of the feedforward amount when the main steam pressure deviation is large.

[0101] When the AGC target load command is greater than the actual power generation load Values When the AGC target load command is less than the actual power generation load, Values When the AGC target load command equals the actual power generation load, Values .

[0102] In operating condition interval identification, the pressure-load valve position coupling feedforward model determines the current operating condition interval based on the load setpoint, the actual main steam pressure, and the integrated valve position feedback. Specifically, multiple load-main steam pressure valve position operating condition intervals can be established based on historical AGC operation samples. Each load-main steam pressure valve position operating condition interval is jointly defined by the load setpoint range, the actual main steam pressure range, and the integrated valve position feedback range. Historical AGC operation samples can be derived from the operation records of AGC in operation in the DCS historical database, including data such as load setpoint, actual main steam pressure, main steam pressure setpoint, actual power generation load, integrated valve position feedback, AGC target load command, and rate-based load command.

[0103] In the Within the control cycle of each DCS main control regulating loop, the operating condition interval identification is performed to form the current operating point based on the current load setpoint, the current actual main steam pressure, and the current integrated valve position feedback. The current operating condition interval is then determined from multiple load main steam pressure valve position operating condition intervals. When the current operating point falls within a load main steam pressure valve position operating condition interval, that interval is designated as the current operating condition interval. When the current operating point is located within the boundary of two adjacent load main steam pressure valve position operating condition intervals, the model parameters of the two adjacent intervals are weighted and transitioned based on their relative positions. The weighted and transitioned model parameters are then used as the model parameter set corresponding to the current operating condition interval. This weighted transition reduces the impact of sudden changes in model parameters on valve position control output when the current operating point switches between adjacent operating condition intervals.

[0104] Before valve position switching, the model parameter set corresponding to the current operating condition range can be determined or updated. The model parameter set includes the quotient feedforward coefficient, main steam pressure margin correction coefficient, lower limit of pressure margin correction, upper limit of pressure margin correction, valve position switching slope coefficient, valve position switching bias coefficient, feedforward change compensation coefficient, and valve position feedback change compensation coefficient. For each load main steam pressure valve position operating condition range, a separate set of model parameter sets can be set. The model parameter set can be initially calibrated based on historical AGC operation samples, analog coefficients in the original DCS main control regulation loop, field valve position switching function, and load correction function, or it can be corrected using trial operation data.

[0105] In one specific embodiment, the determination of the model parameter set may include the following steps: First, divide the load main steam pressure valve position operating condition interval according to the load setpoint range, the actual main steam pressure range, and the integrated valve position feedback range; second, assign historical AGC operation samples to the corresponding load main steam pressure valve position operating condition intervals; third, use AGC response time, main steam pressure fluctuation, integrated valve position single-cycle change, load overshoot, and the deviation between the predicted integrated valve position change and the integrated valve position feedback change corresponding to the valve position-based main steam pressure feedforward as parameter evaluation quantities to determine the model parameter set within each load main steam pressure valve position operating condition interval; finally, after the pressure-load valve position coupled feedforward model is put into use, perform rolling correction on the model parameter set based on newly added AGC operation samples. The above parameter determination process is used to ensure that the quotient feedforward parameters and valve position conversion parameters under the same current operating condition interval are matched in a coordinated manner, thereby improving the accuracy of converting the main steam pressure quotient feedforward into the valve position-based main steam pressure feedforward.

[0106] Before determining the model parameter set, historical AGC operation samples can be screened. The screening process includes: removing operation samples from when AGC is not engaged; removing operation samples where any data in the actual main steam pressure, main steam pressure setpoint, load setpoint, actual power generation load, or integrated valve position feedback is invalid; using the moment when the AGC target load command changes as the start time of the response sample segment, and the moment when the actual power generation load crosses the AGC response dead zone and remains there for a preset duration as the end time of the response sample segment, resulting in response time-related samples; calculating the AGC response time, main steam pressure fluctuation, integrated valve position single-cycle change, and load overshoot based on the response time-related samples; and then assigning the response time-related samples to the corresponding load main steam pressure valve position operating condition intervals according to their respective load main steam pressure valve position operating condition intervals. Through this screening, the determination of the model parameter set is based on samples directly related to the AGC response process, rather than on irrelevant operation data.

[0107] In valve position conversion, the main steam pressure quotient feedforward is converted into a valve-positioned main steam pressure feedforward according to the dynamic valve position conversion relationship. The valve-positioned main steam pressure feedforward is used to input the DCS main control integrated valve position summation loop, and its dimensions are consistent with the input dimensions of the DCS main control integrated valve position summation loop. In one embodiment, the valve-positioned main steam pressure feedforward is determined according to the following dynamic valve position conversion relationship:

[0108] ;

[0109] In the formula, For the first The valve position-based main steam pressure feedforward of the control cycle of each DCS main control regulating loop. For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. This is the feedforward amount of the main steam pressure quotient for the control cycle of the previous DCS main control regulating loop. This is a comprehensive valve position feedback buffer for the control cycle of the previously completed DCS main control regulation loop. To further buffer the control cycle of the completed DCS main control regulation loop, the integrated valve position feedback is used. This represents the valve position transition slope coefficient corresponding to the current operating condition range. This is the valve position switching bias coefficient corresponding to the current operating condition range. This is the feedforward variation compensation coefficient corresponding to the current operating condition range. This is the valve position feedback change compensation coefficient corresponding to the current operating condition range. For the first The feedforward enable coefficient of the control cycle of the main control regulation loop of the DCS machine;

[0110] Among them, the valve position transition slope coefficient is used to convert the main steam pressure quotient feedforward into an equivalent valve position channel quantity; the valve position transition bias coefficient is used to compensate for the basic deviation of valve position transition under the current operating condition range; the feedforward change compensation coefficient is used to compensate for the impact of single-cycle changes in the main steam pressure quotient feedforward on the valve-positioned main steam pressure feedforward; and the valve position feedback change compensation coefficient is used to correct the valve-positioned main steam pressure feedforward based on the comprehensive valve position feedback change between two adjacent completed control cycles. Instead of using the current cycle's overall valve position feedback difference for calculation, it can utilize cached data from completed control cycles, avoiding the formation of an algebraic loop by relying on the current cycle's output calculation for current cycle feedback.

[0111] Feedforward enable coefficient Used to control the output of the main steam pressure feedforward for valve positioning. When the feedforward enable condition is met, The dynamic valve position switching relationship outputs the main steam pressure feedforward based on the current cycle data; when the feedforward enabling condition is not met... The output of the dynamic valve position switching relationship is zero, and the valve-positioned main steam pressure feedforward enters the lockout state with a zero value. Feedforward enabling conditions can include AGC activation being valid, model input data being valid, and the AGC adjustment direction not being zero. Conditions for valid model input data include: no communication interruptions, bad points, over-limits, freezes, or quality level anomalies in the AGC target load command, rate-after-load command, load setpoint, actual power generation load, actual main steam pressure, main steam pressure setpoint, and integrated valve position feedback. When any model input data is invalid, the model input data validity condition is not met, and the feedforward enabling coefficient is 0.

[0112] Within each control cycle of the DCS main control regulation loop, S3 can be executed according to the following timing sequence. At the beginning of the control cycle, the model input data of the current cycle, the main steam pressure quotient feedforward quantity buffered in the control cycle of the previous DCS main control regulation loop, the integrated valve position feedback buffered in the previous completed control cycle, and the integrated valve position feedback buffered in the control cycle before that are latched. During the control cycle, the pressure load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression are executed sequentially. At the end of the control cycle, the valve position-based main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction are output to the subsequent DCS main control integrated valve position summation stage. After the control cycle ends, the historical cache is updated. The current cycle's main steam pressure quotient feedforward is used as the main steam pressure quotient feedforward in the control cycle cache of the previous DCS main control regulating loop in the next control cycle. The currently collected integrated valve position feedback is used as the integrated valve position feedback in the control cycle cache of the previous completed DCS main control regulating loop in the next control cycle. The integrated valve position feedback in the control cycle cache of the previous completed DCS main control regulating loop is then shifted to the integrated valve position feedback in the control cycle cache of the next completed DCS main control regulating loop in the next control cycle.

[0113] When the feedforward enable condition is met for the first time, the difference term is initialized, so that... and make This initialization process is executed only in the first control cycle when the feedforward enable condition changes from false to true. This is to prevent sudden changes in the valve-positioned main steam pressure feedforward due to missing or discontinuous historical buffer values. In subsequent control cycles where the feedforward enable condition is continuously met, the normal buffer update process is followed. and .

[0114] In small deviation suppression, the equivalent value of the valve position channel corresponding to the load correction is generated based on the deviation between the AGC target load command and the rate-adjusted load command. Specifically, small deviation suppression determines a first deviation threshold, a second deviation threshold, and a preset load correction upper limit based on the current operating condition range, with the first deviation threshold being less than the second deviation threshold. When the absolute value of the deviation between the AGC target load command and the rate-adjusted load command is not greater than the first deviation threshold, the equivalent value of the valve position channel corresponding to the load correction is set to zero to reduce invalid valve position disturbances caused by small deviations. When the absolute value of the deviation is greater than the first deviation threshold but less than the second deviation threshold, the equivalent value of the valve position channel corresponding to the load correction is determined according to the monotonic piecewise mapping relationship corresponding to the current operating condition range, and the direction of the equivalent value of the valve position channel corresponding to the load correction is determined by the sign of the deviation. When the absolute value of the deviation is not less than the second deviation threshold, the absolute value of the equivalent value of the valve position channel corresponding to the load correction is limited to the preset load correction upper limit. The aforementioned first deviation threshold, second deviation threshold, preset load correction upper limit, and monotonic piecewise mapping relationship can be tuned based on the original linear function, the modified linear function of the load correction loop in the DCS, and field trial operation data.

[0115] After processing in S3, the pressure-load valve position coupling feedforward model outputs two quantities: the valve-positioned main steam pressure feedforward and the equivalent quantity of the valve position channel corresponding to the load correction. The valve-positioned main steam pressure feedforward is jointly determined by the AGC adjustment direction, the actual value of the main steam pressure, the main steam pressure setpoint, the load setpoint, the current operating range, and the model parameter set. The equivalent quantity of the valve position channel corresponding to the load correction is jointly determined by the deviation between the AGC target load command and the rate-adjusted load command, the current operating range, and the small deviation suppression rule. Both participate in the subsequent summation in a form consistent with the input dimensions of the DCS main control integrated valve position summation stage, providing input for S4 to form the main control integrated valve position control output.

[0116] S4: Connect to the DCS main control integrated valve position summation loop and form the main control integrated valve position control output;

[0117] In this embodiment, S4 is used to connect the valve-positioned main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction output from S3 into the DCS main control integrated valve position summation loop, and form the main control integrated valve position control output quantity while retaining the control function of the original DCS main control regulation loop. S4 does not cancel the original main control regulation loop, but adds an additional feedforward quantity to the original DCS main control integrated valve position summation loop, thereby realizing the engineering connection between the new feedforward logic and the original control logic.

[0118] The connection relationships of the original DCS main control regulation circuit and the added pressure load valve position coupling feedforward model are as follows: Figure 4 and Figure 5 As shown; where, Figure 4This is used to explain the main steam pressure deviation PID branch, the main control basic integrated valve position quantity, and the integrated valve position output logic in the original DCS main control regulation loop. Figure 5 This is used to illustrate the connection relationship between the valve position main steam pressure feedforward and the equivalent valve position channel quantity corresponding to the load correction, which are used as additional feedforward quantities and connected to the DCS main control integrated valve position summation link.

[0119] Specifically, the DCS main control control loop retains the original main steam pressure deviation PID branch. This branch generates the main steam pressure deviation valve position adjustment based on the deviation between the main steam pressure setpoint and the actual main steam pressure. This adjustment still participates in the integrated valve position control according to the original DCS main control control loop's PID control logic, and is not replaced by the valve position feedforward or the equivalent valve position channel quantity corresponding to load correction. This setup aims to preserve the original closed-loop control capability, allowing the newly added feedforward logic to operate as an additional quantity on the original control structure, thus avoiding impacting the stability of the DCS main control control loop by directly replacing the original PID branch.

[0120] Within the control cycle of each DCS main control regulating loop, the main control basic integrated valve position quantity obtained in S1, the main steam pressure deviation valve position adjustment quantity output by the original main steam pressure deviation PID branch, the valve position-based main steam pressure feedforward quantity generated in S3, and the equivalent quantity of the valve position channel corresponding to the load correction generated in S3 are input into the DCS main control integrated valve position summation loop. All four quantities adopt valve position engineering quantities or percentage openings with the same dimensions as the input quantities in the DCS main control integrated valve position summation loop.

[0121] When adding additional feedforward, the valve position feedforward of the main steam pressure and the equivalent valve position channel corresponding to the load correction are used as additional feedforward and added to the DCS main control integrated valve position summation loop. The additional feedforward is only used to provide supplementary regulation in addition to the original main control basic integrated valve position and main steam pressure deviation valve position adjustment, and does not change the input, output and control parameters of the original main steam pressure deviation PID branch.

[0122] Within the control cycle of each DCS main control regulating loop, the DCS main control integrated valve position summation stage first calculates the computer main control integrated valve position pre-output based on the main control basic integrated valve position quantity, the main steam pressure deviation valve position adjustment quantity, the valve position feedforward quantity of the main steam pressure, and the equivalent quantity of the valve position channel corresponding to the load correction. The main control integrated valve position pre-output is used to determine whether the summation of newly added feedforward quantities exceeds the preset integrated valve position allowable range. The preset integrated valve position allowable range can be determined based on the allowable opening range of the turbine regulating valve, the upper and lower limits of the DCS integrated valve position, and the unit's operational safety constraints.

[0123] When the feedforward enabling condition is not met, the additional feedforward quantity is locked out. The feedforward enabling condition can be consistent with the feedforward enabling condition in S3, including AGC activation status being valid, model input data being valid, and AGC adjustment direction not being zero. The locking out process sets both the valve position feedforward quantity corresponding to the valve position correction and the equivalent quantity of the valve position channel to zero, so that the integrated valve position control output of the main engine control is still formed by the basic integrated valve position quantity of the main engine control and the valve position adjustment quantity of the main engine pressure deviation, thereby maintaining the control function of the original main engine pressure deviation PID branch.

[0124] When the feedforward enabling condition is met and the pre-output quantity of the main control integrated valve position is within the preset integrated valve position allowable range, the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction are not subjected to grouped amplitude limiting processing, and participate in the DCS main control integrated valve position summation process according to the value generated by S3.

[0125] When the feedforward enabling condition is met, but the pre-output quantity of the main control integrated valve position exceeds the preset allowable range of the integrated valve position, group limiting processing is applied to the valve-positioned main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction. Group limiting processing only adjusts the above two additional feedforward quantities, without changing the basic integrated valve position quantity of the main control and the main steam pressure deviation valve position adjustment quantity. Group limiting processing can simultaneously reduce the valve-positioned main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction using the same limiting ratio, so that the adjusted main control integrated valve position control output quantity falls within the preset allowable range of the integrated valve position, while maintaining the relative proportional relationship between the two additional feedforward quantities. The same limiting ratio can be determined based on the difference between the preset allowable range of the integrated valve position and the pre-output quantity of the main control integrated valve position.

[0126] When the base output formed by the main control system's basic integrated valve position and the main steam pressure deviation valve position adjustment exceeds the preset integrated valve position allowable range, or when the direction of the additional feedforward cannot bring the main control system's integrated valve position control output back to the preset integrated valve position allowable range, the two additional feedforwards can be locked out or the group limiting ratio can be set to zero, so that the additional feedforwards no longer amplify the risk of the original DCS main control system's control loop exceeding the output limit. In this case, the protection logic, valve position limiting logic, or operator intervention logic of the original DCS main control system's control loop will still be executed according to the original system settings. This embodiment only constrains the newly added additional feedforwards.

[0127] After interlocking or group limiting processing, the processed valve-positioned main steam pressure feedforward quantity and the processed load correction corresponding valve position channel equivalent quantity are sent together with the turbine main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity into the DCS turbine main control integrated valve position summation stage to form the turbine main control integrated valve position control output quantity. This turbine main control integrated valve position control output quantity is used to participate in the subsequent turbine regulating valve control.

[0128] Through the above steps S1 to S4, this embodiment, while retaining the original DCS main control regulating loop control structure, integrates the feedforward effect formed by the relationship between main steam pressure and load setpoint, the comprehensive valve position status, and the small deviation correction between the target load command and the rate-followed load command into the main control comprehensive valve position control output. Therefore, when the AGC load command changes, the DCS main control regulating loop can obtain an additional feedforward regulation amount that matches the current operating state, improving the timeliness of valve position regulation in the initial stage of load response. Simultaneously, it reduces ineffective disturbances and the risk of exceeding limits through small deviation suppression and grouped amplitude limiting processing.

[0129] like Figure 2 As shown, another embodiment of the present invention also provides a thermal power AGC coupled feedforward valve position control system. This system is applied to the above-mentioned thermal power AGC coupled feedforward valve position control method and can be deployed in the main control and regulation loop of the DCS of a thermal power unit, serving as an additional feedforward control logic execution for the original main control and regulation loop. The system includes a data acquisition module, a quotient calculation module, an operating condition identification module, a valve position conversion module, a small deviation suppression module, and a valve position output module. The quotient calculation module, operating condition identification module, valve position conversion module, and small deviation suppression module together constitute a pressure load valve position coupled feedforward model.

[0130] The data acquisition module is used to collect operating data of the DCS main control and regulation loop when the thermal power unit's AGC (Automatic Guided Vehicle) is engaged. The operating data includes model input data and the basic integrated valve position values ​​of the main control system. Model input data includes AGC target load commands, rate-following load commands, load setpoints, actual power generation load, actual main steam pressure, main steam pressure setpoints, and integrated valve position feedback. The data acquisition module also performs validity checks on the model input data and sends it to the quotient calculation module, operating condition identification module, and small deviation suppression module, respectively. It also sends the basic integrated valve position values ​​of the main control system to the valve position output module.

[0131] The quotient calculation module is used to determine the AGC adjustment direction based on the AGC target load command and the actual power generation load, and to generate the main steam pressure quotient feedforward quantity based on the quotient relationship between the AGC adjustment direction, the actual value of the main steam pressure and the load set value. The quotient calculation module is also used to correct the main steam pressure quotient feedforward quantity using the directional coupling pressure margin limiting factor based on the deviation between the actual value of the main steam pressure and the main steam pressure set value and the model parameter group corresponding to the current operating condition range.

[0132] The operating condition identification module is used to determine the current operating point based on the load setpoint, the actual main steam pressure, and the integrated valve position feedback, and to identify the current operating condition interval from multiple load, main steam pressure, and valve position operating condition intervals. The operating condition identification module also outputs the current operating condition interval number and the corresponding model parameter set to the quotient calculation module and the valve position conversion module.

[0133] The valve position conversion module is used to convert the main steam pressure quotient feedforward quantity output by the quotient calculation module into a valve-positioned main steam pressure feedforward quantity based on the model parameter group corresponding to the current operating condition range. The valve position conversion module is also used to determine the feedforward enable coefficient based on the validity of the AGC activation state, the validity of the model input data, and the fact that the AGC adjustment direction is not zero, and to control the output of the valve-positioned main steam pressure feedforward quantity according to the feedforward enable coefficient; when the feedforward enable condition is not met, the valve position conversion module sets the valve-positioned main steam pressure feedforward quantity to zero.

[0134] The small deviation suppression module is used to generate the equivalent value of the valve position channel corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and to suppress the equivalent value of the valve position channel corresponding to the load correction when the deviation is within the preset small deviation range based on the small deviation suppression parameters corresponding to the current operating condition range.

[0135] The valve position output module receives the overall valve position quantity from the receiver's main control system, the main steam pressure deviation valve position adjustment quantity output by the PID branch of the original DCS main control regulation loop, the valve-positioned main steam pressure feedforward quantity, and the equivalent quantity of the valve position channel corresponding to load correction. It then inputs the valve-positioned main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to load correction as additional feedforward quantities into the DCS main control system's overall valve position summation loop. This additional feedforward quantity does not replace the output of the original main steam pressure deviation PID branch.

[0136] When the pre-output quantity of the main control integrated valve position exceeds the preset allowable range of the integrated valve position, the valve position output module performs grouped amplitude limiting processing on the valve-positioned main steam pressure feedforward quantity and the valve position channel equivalent quantity corresponding to the load correction according to the same amplitude limiting ratio, without changing the basic integrated valve position quantity of the main control and the main steam pressure deviation valve position adjustment quantity. After the interlocking processing or group amplitude limiting processing, the valve-positioned main steam pressure feedforward quantity and the valve position channel equivalent quantity corresponding to the load correction, together with the basic integrated valve position quantity of the main control and the main steam pressure deviation valve position adjustment quantity, form the integrated valve position control output quantity of the main control.

[0137] In terms of module connections, the data acquisition module is connected to the quotient calculation module, operating condition identification module, small deviation suppression module, and valve position output module, respectively; the operating condition identification module is connected to the quotient calculation module and the valve position conversion module, respectively; the quotient calculation module is connected to the valve position conversion module; the valve position conversion module and the small deviation suppression module are connected to the valve position output module, respectively; and the valve position output module is connected to the DCS main control integrated valve position summation loop. Through this system structure, without altering the basic control logic of the original DCS main control regulation loop, the additional feedforward quantity output from the pressure load valve position coupling feedforward model can be incorporated into the main control integrated valve position control output process.

[0138] Therefore, this embodiment forms a continuous processing procedure through pressure load quotient calculation, operating condition interval identification, valve position conversion, and small deviation suppression. The generated valve-positioned main steam pressure feedforward and the equivalent valve position channel quantity corresponding to load correction are used as additional feedforward quantities and input into the DCS main control integrated valve position summation loop. Based on retaining the original main steam pressure deviation PID branch and the main control basic integrated valve position quantity, the main control integrated valve position control output is formed. Through this method, the main control integrated valve position control output can better adapt to AGC load command changes and small deviation operating conditions, thereby improving the timeliness of adjustment in the initial stage of load response and enhancing the accuracy of the main control regulation loop and the stability of AGC response.

[0139] In summary, this invention integrates the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction into the DCS main control integrated valve position summation loop, enabling the main control integrated valve position control output to better adapt to AGC load command changes and small deviation conditions. This improves the timeliness of adjustment in the initial stage of load response and enhances the accuracy of the main control adjustment loop and the stability of AGC response.

[0140] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., refer to specific features, structures, steps, parameters, or control logic described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. Without contradiction, those skilled in the art can combine the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0141] The control flow, functional modules, and DCS logical connection relationships described in this specification are used to illustrate the implementation of this application. Those skilled in the art can make equivalent adjustments to the sequence of steps, combination of functional modules, parameter configuration, or signal connection methods based on the specific configuration of the DCS system, control cycle, signal interfaces, and field operating constraints; as long as the technical solution described in this application can be implemented, it should not be construed as departing from the protection scope of this application.

[0142] The above description is merely a specific embodiment of this application and is not intended to limit the scope of protection of this application. All equivalent variations, substitutions, or combinations that can be conceived by those skilled in the art within the scope of the technical concept disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application is determined by the claims.

Claims

1. A method for coupling feedforward valve position control in thermal power AGC, characterized in that, Includes the following steps: When the thermal power unit is in AGC mode, the operating data of the DCS main control regulation loop is collected. The operating data includes model input data and the basic integrated valve position of the main control unit. The model input data includes AGC target load command, rate-after-load command, load setpoint, actual power generation load, actual main steam pressure, main steam pressure setpoint, and integrated valve position feedback. Input the model input data into the pressure load valve position coupled feedforward model. The pressure load valve position coupled feedforward model performs pressure load quotient calculation, operating condition interval identification, valve position conversion and small deviation suppression. The pressure load quotient calculation generates the main steam pressure quotient feedforward based on the AGC adjustment direction, the quotient relationship between the actual value of the main steam pressure and the load setpoint. Operating conditions The interval identification determines the current operating condition interval based on the load setpoint, the actual value of the main steam pressure, and the comprehensive valve position feedback. The current operating condition interval is the load, main steam pressure, and valve position operating condition interval. The valve position conversion converts the main steam pressure quotient feedforward into the valve position-based main steam pressure feedforward based on the model parameter group corresponding to the current operating condition interval. Small deviation suppression generates the valve position channel equivalent quantity corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and suppresses the valve position channel equivalent quantity corresponding to the load correction when the deviation is within the preset small deviation range. The valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction are connected to the DCS main control integrated valve position summation link, and together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity, they form the main control integrated valve position control output quantity. The main steam pressure deviation valve position adjustment quantity is formed by the deviation between the main steam pressure set value and the actual main steam pressure value through PID regulation.

2. The method for coupling feedforward valve position control in thermal power AGC according to claim 1, characterized in that, The step of inputting model input data into the pressure load valve position coupled feedforward model includes: The pressure load valve position coupling feedforward model is executed through the additional feedforward function block in the DCS main control regulation loop. Add a feedforward function block to the signal corresponding to the model input data; The additional feedforward function block outputs the valve position main steam pressure feedforward quantity and the equivalent quantity of the valve position channel corresponding to the load correction, according to the control cycle of the DCS main control regulation loop.

3. The method for coupling feedforward valve position control in thermal power AGC according to claim 1, characterized in that, The calculation of the pressure load quotient includes: The direction of AGC adjustment is determined based on the relationship between the target load command and the actual power generation load. Based on the AGC adjustment direction, the actual value of the main steam pressure, the setpoint of the main steam pressure, and the load setpoint, the feedforward amount of the main steam pressure quotient is generated according to the following model relationship: ； Directional coupling pressure margin limiting factor Determined according to the following relationship: ； In the formula, For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. For the first The direction of AGC adjustment in the control cycle of each DCS main control adjustment loop. For the first The actual value of the main steam pressure during the control cycle of the DCS main control regulating loop. For the first The main steam pressure setpoint for the control cycle of the DCS main control regulating loop. For the first The load setpoint of the control cycle of each DCS main control regulation loop. A load correction constant with the same dimensions as the load setpoint. A pressure correction constant with the same dimensions as the main steam pressure setpoint, and , , For the first The control cycle of each DCS main control regulation loop corresponds to the current operating condition interval number. The feedforward coefficient is the quotient value corresponding to the current operating condition interval. This is the main steam pressure margin correction factor corresponding to the current operating condition range. Adjust the lower limit of the pressure margin corresponding to the current operating condition range. Adjust the upper limit of the pressure margin corresponding to the current operating condition range, and satisfy the following conditions: ; When the AGC target load command is greater than the actual power generation load Values When the AGC target load command is less than the actual power generation load, Values When the AGC target load command equals the actual power generation load, Values .

4. The method for coupling feedforward valve position control in thermal power AGC according to claim 1, characterized in that, The identification of the operating condition range includes: Based on historical AGC operation samples, multiple load main steam pressure valve position operating condition ranges are established. Each load main steam pressure valve position operating condition range is jointly defined by the load set value range, the actual main steam pressure value range, and the comprehensive valve position feedback range. Based on the load setpoint, actual main steam pressure, and integrated valve position feedback within the control cycle of the current DCS main control regulating loop, the current operating condition range is determined from multiple load main steam pressure valve position operating condition ranges; When the current operating point, formed by the load setpoint, the actual main steam pressure, and the integrated valve position feedback, is located within the boundary of two adjacent load main steam pressure valve position operating condition intervals, the model parameters of the two adjacent load main steam pressure valve position operating condition intervals are weighted and transitioned according to the relative position of the current operating point and the two adjacent load main steam pressure valve position operating condition intervals, and the weighted and transitioned model parameters are used as the model parameters of the current operating condition interval.

5. The method for coupling feedforward valve position control in thermal power AGC according to claim 4, characterized in that, The valve position switching includes: The main steam pressure quotient feedforward is converted into a valve position-based main steam pressure feedforward according to the dynamic valve position conversion relationship. The valve position-based main steam pressure feedforward is then used to access the DCS main control integrated valve position summation link. The dynamic valve position switching relationship is as follows: ； In the formula, For the first The valve position-based main steam pressure feedforward of the control cycle of each DCS main control regulating loop. For the first The main steam pressure quotient feedforward of the control cycle of the DCS main control regulating loop. This is the feedforward amount of the main steam pressure quotient for the control cycle of the previous DCS main control regulating loop. This is a comprehensive valve position feedback buffer for the control cycle of the previously completed DCS main control regulation loop. To further buffer the control cycle of the completed DCS main control regulation loop, the integrated valve position feedback is used. This represents the valve position transition slope coefficient corresponding to the current operating condition range. This is the valve position switching bias coefficient corresponding to the current operating condition range. This is the feedforward variation compensation coefficient corresponding to the current operating condition range. This is the valve position feedback change compensation coefficient corresponding to the current operating condition range. For the first The feedforward enable coefficient of the control cycle of the main control regulation loop of the DCS machine; When the feedforward enable condition is met, When the feedforward enable condition is not met, The feedforward enable conditions are: AGC is in a valid state, the model input data is valid, and the AGC adjustment direction is not zero. The valve position switching slope coefficient and feedforward change compensation coefficient are used to convert the main steam pressure quotient feedforward amount and the single-cycle change amount of the main steam pressure quotient feedforward amount into the valve position channel equivalent amount with the same dimensions as the input quantity of the DCS main control integrated valve position summation link; the valve position switching bias coefficient is used to compensate for the valve position switching deviation under the current operating condition range; the valve position feedback change compensation coefficient is used to correct the valve position-based main steam pressure feedforward amount according to the integrated valve position feedback change amount between two adjacent completed control cycles. When the feedforward enable condition is met for the first time, the difference term is initialized, so that... And make .

6. The method for coupling feedforward valve position control in thermal power AGC according to claim 5, characterized in that, Before the valve position conversion converts the main steam pressure quotient feedforward into the valve-positioned main steam pressure feedforward based on the model parameters of the current operating range, it also includes determining or updating the model parameter group corresponding to the current operating range. Determining or updating the model parameter group corresponding to the current operating range includes: Based on historical AGC operation samples, a set of model parameters is determined for each load main steam pressure valve position operating condition range. The set of model parameters includes quotient feedforward coefficient, main steam pressure margin correction coefficient, pressure margin correction lower limit, pressure margin correction upper limit, valve position transition slope coefficient, valve position transition bias coefficient, feedforward change compensation coefficient, and valve position feedback change compensation coefficient. When determining the model parameter set, the AGC response time, main steam pressure fluctuation, single-cycle change of integrated valve position, load overshoot, and the deviation between the valve-positioned main steam pressure feedforward and the integrated valve position feedback change are used as parameter evaluation quantities. Before the pressure load valve position coupling feedforward model is put into use, the model parameter set is initially determined based on historical AGC operation samples; After the pressure load valve position coupling feedforward model is put into use, the model parameter group is rolled over based on the newly added AGC operation samples.

7. The method for coupling feedforward valve position control in thermal power AGC according to claim 6, characterized in that, Before determining the model parameters corresponding to each load main steam pressure valve position operating condition range based on historical AGC operation samples, the historical AGC operation samples are screened, including: Remove operating samples that are not in the AGC (Automatic Guided Vehicle) state; Remove any operating samples with invalid data from the following: actual main steam pressure, set main steam pressure, load set value, actual power generation load, or integrated valve position feedback. The start time of the response sample segment is taken as the moment when the AGC target load command changes, and the end time of the response sample segment is taken as the moment when the actual power generation load crosses the AGC response dead zone and a preset holding time has elapsed, thus obtaining the response time-related sample. Calculate the AGC response time, main steam pressure fluctuation, single-cycle change of integrated valve position, and load overshoot based on relevant response time samples. Based on the load main steam pressure valve position operating condition range to which the response time-related samples belong, the response time-related samples are assigned to the corresponding load main steam pressure valve position operating condition range.

8. The method for coupling feedforward valve position control in thermal power AGC according to claim 1, characterized in that, The small deviation suppression includes: The equivalent valve position channel quantity corresponding to the load correction is generated based on the deviation between the AGC target load command and the rate-based load command. The first deviation threshold, the second deviation threshold, and the preset load correction upper limit are determined based on the current operating condition range, and the first deviation threshold is less than the second deviation threshold. When the absolute value of the deviation is not greater than the first deviation threshold, the equivalent value of the valve position channel corresponding to the load correction is set to zero. When the absolute value of the deviation is greater than the first deviation threshold and less than the second deviation threshold, the equivalent quantity of the valve position channel corresponding to the load correction is determined according to the monotonic piecewise mapping relationship corresponding to the current working condition interval. The direction of the equivalent quantity of the valve position channel corresponding to the load correction is determined by the sign of the deviation. When the absolute value of the deviation is not less than the second deviation threshold, the absolute value of the equivalent quantity of the valve position channel corresponding to the load correction is limited to the preset load correction upper limit.

9. A method for controlling the position of a feedforward valve in a thermal power plant AGC system according to claim 5, characterized in that, The step of integrating the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction into the DCS main control integrated valve position summation process includes: The original main steam pressure deviation PID branch in the DCS main control regulation loop is retained; The valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction are used as additional feedforward quantities and input into the DCS main control integrated valve position summation link. The additional feedforward quantity does not replace the output of the original main steam pressure deviation PID branch. Within the control cycle of each DCS main control regulation loop, the computer main control comprehensive valve position pre-output is calculated based on the main control basic comprehensive valve position quantity, the main steam pressure deviation valve position adjustment quantity, the valve position feedforward quantity of the main steam pressure, and the equivalent quantity of the valve position channel corresponding to the load correction. When the feedforward enabling condition is not met, the additional feedforward quantity is locked out, and the original main steam pressure deviation PID branch participates in the main control integrated valve position control output. When the pre-output quantity of the main control integrated valve position exceeds the preset allowable range of the integrated valve position, the equivalent quantity of the valve position channel corresponding to the valve position feedforward quantity and the load correction is subjected to grouped amplitude limiting processing according to the same amplitude limiting ratio that makes the pre-output quantity of the main control integrated valve position fall into the preset allowable range of the integrated valve position, and the basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity of the main control are not changed. The valve position feedforward quantity of the main steam pressure after the lockout processing or group amplitude limiting processing, the equivalent quantity of the valve position channel corresponding to the load correction, together with the main engine control basic comprehensive valve position quantity and the main steam pressure deviation valve position adjustment quantity, form the main engine control comprehensive valve position control output quantity.

10. A thermal power plant AGC coupled feedforward valve position control system, used to execute a thermal power plant AGC coupled feedforward valve position control method as described in any one of claims 1-9, characterized in that, include: The data acquisition module is used to collect the operating data of the DCS main control regulation loop when the AGC of the thermal power unit is in operation. The operating data includes model input data and the basic comprehensive valve position of the main control unit. The model input data includes AGC target load command, rate-after-load command, load setpoint, actual power generation load, actual value of main steam pressure, setpoint of main steam pressure and comprehensive valve position feedback. The quotient calculation module is used to generate the main steam pressure quotient feedforward based on the quotient relationship between the AGC adjustment direction, the actual value of the main steam pressure and the load set value, and to correct the main steam pressure quotient feedforward based on the directional coupling pressure margin limiting factor. The operating condition identification module is used to determine the current operating condition range based on the load setpoint, the actual main steam pressure, and the comprehensive valve position feedback. The current operating condition range is the load, main steam pressure, and valve position operating condition range. The valve position conversion module is used to convert the main steam pressure quotient feedforward into a valve-positioned main steam pressure feedforward based on the model parameter group corresponding to the current operating condition range, and to control the output of the valve-positioned main steam pressure feedforward according to the feedforward enable coefficient. The small deviation suppression module is used to generate the equivalent amount of the valve position channel corresponding to the load correction based on the deviation between the AGC target load command and the rate-followed load command, and to suppress the equivalent amount of the valve position channel corresponding to the load correction when the deviation is within the preset small deviation range. The valve position output module is used to input the valve position feedforward quantity of the main steam pressure and the equivalent quantity of the valve position channel corresponding to the load correction into the DCS main control integrated valve position summation link, and together with the main control basic integrated valve position quantity and the main steam pressure deviation valve position adjustment quantity, it forms the main control integrated valve position control output quantity. The main steam pressure deviation valve position adjustment quantity is formed by the deviation between the main steam pressure set value and the actual main steam pressure value through PID regulation. The quotient calculation module, operating condition identification module, valve position conversion module, and small deviation suppression module together constitute the pressure load valve position coupling feedforward model.

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