A method for AGC response delay compensation control in thermal power units

Abstract

This invention discloses an AGC response delay compensation control method for thermal power units, relating to the field of thermal power generation control technology. The invention includes the following steps: collecting unit operating parameters and performing filtering preprocessing; triggering compensation when the power deviation exceeds the dead zone and the command change rate meets the standard, recording the spray reference frequency and historical fuel quantity and power; identifying the boiler's first-order inertia plus pure time delay model online using historical fuel quantity and power; inputting the AGC command into the model to generate the boiler's estimated power, and calculating the difference between the estimated power and the command to obtain the power deficit to be compensated; converting the power deficit into a change in the set exhaust pressure using a slight increase in the exhaust pressure output coefficient; constructing and inverting the spray frequency-exhaust pressure transfer function, applying it to the change in the set exhaust pressure to obtain the feedforward spray frequency increment; issuing a spray command after the frequency increment is limited, back pressure safety checked, and rate limited; and decaying the spray frequency to the reference at a fixed rate after the exit condition is met, resuming compensation if the deviation exceeds the limit during this period.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation control technology, and in particular relates to an AGC response delay compensation control method for thermal power units. Background Technology

[0002] When responding to automatic generation control commands issued by the power grid dispatch, thermal power units need to quickly and accurately track changes in load commands to meet the performance requirements of the power grid's secondary frequency regulation. However, there are two links in the power regulation of thermal power units with vastly different response speeds: the turbine regulating valve can adjust the output within seconds by changing the steam flow, while the boiler combustion system, limited by the pure lag and thermal inertia of pulverization, transportation, combustion, and steam-water processes, often requires tens of seconds or even minutes for the unit's electrical power to produce a substantial response after the fuel quantity command changes. This inherent contradiction leads to the boiler side being unable to provide matching output support in the initial stage of AGC commands that cause a step or continuous ramp-up, resulting in a significant tracking delay between the unit's actual power output and the dispatch command, which in turn causes deviations in the integral power assessment, affecting the unit's regulation performance and economic benefits in the ancillary services market.

[0003] To alleviate the aforementioned contradictions, conventional time-delay compensation methods mainly rely on turbine control valve throttling, condensate throttling, or thermal storage devices to provide short-term power support. Among these, turbine control valve throttling sacrifices some operational economy for rapid load response capability; condensate throttling utilizes changes in the water level of the low-pressure heater or deaerator to release the energy stored in the regenerative system to quickly change the unit output; thermal or energy storage devices achieve rapid power throughput through external energy buffering. However, in thermal power units equipped with indirect air-cooled tower variable frequency spray systems, the spray system itself has the ability to adjust the circulating water temperature at the outlet of the indirect air-cooled tower by changing the frequency of the spray water pump, thereby affecting the turbine exhaust pressure and ultimately changing the unit output. A small change in the turbine exhaust pressure can change the effective enthalpy drop of the last stage of the low-pressure cylinder within seconds, thus rapidly causing an increase or decrease in electrical power. This response speed is much faster than boiler combustion regulation, providing the physical basis for becoming a rapid power compensation resource.

[0004] However, in existing technologies, indirect air-cooled tower spray systems typically operate only as independent regulating loops to maintain design back pressure or optimize cold-end parameters, without being incorporated into the active compensation system for AGC response delay. Existing control strategies lack a systematic method for feedforward calculation of power compensation requirements using the turbine's micro-increase output characteristics and the air-cooled tower spray dynamic model, generating spray frequency commands with phase lead characteristics. This results in the rapid adjustment potential not being effectively utilized in the AGC response phase. Furthermore, directly using the spray system for power compensation faces multiple constraints, including the spray pump frequency range, the safety boundary of the air-cooled tube bundle exhaust pressure, and the thermal stress rate limit of the turbine's last-stage blades. Without corresponding constraint verification mechanisms, rapid back pressure regulation may lead to equipment operating parameters exceeding limits or component lifespan damage. Therefore, we propose an AGC response delay compensation control method for thermal power units. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] This invention relates to an AGC response delay compensation control method for thermal power units, comprising the following steps:

[0007] Step S1: Collect unit operating parameters and perform preprocessing;

[0008] Step S2: Based on the power deviation between the AGC load command and the actual generated power, as well as the command change rate, trigger the delay compensation logic and record the reference frequency and historical data of the sprinkler pump.

[0009] Step S3: Using the fuel quantity command and actual power generation data in the pre-trigger window, identify the nominal boiler response model online;

[0010] Step S4: Input the AGC load command into the nominal boiler response model to generate the estimated boiler power response, and calculate the difference between the AGC load command and the estimated boiler power response to generate the power compensation demand;

[0011] Step S5: Based on the characteristics of the turbine's slight increase in output, the power compensation requirement is converted into the change in the exhaust pressure setpoint.

[0012] Step S6: Construct the spray frequency-exhaust pressure increment transfer function, invert the transfer function and apply it to the change in exhaust pressure setpoint to generate the feedforward spray frequency increment;

[0013] Step S7: Perform multiple constraint checks on the feedforward spray frequency increment to obtain the final spray frequency command and issue it for execution;

[0014] Step S8: Monitor the proximity between the AGC load command and the boiler's estimated power response, as well as the deviation of the measured power. When the exit conditions are met, reduce the spray frequency command to the reference frequency at a fixed rate, and continuously monitor the power deviation during the exit period to determine whether to restore compensation.

[0015] Further, step S1 includes the following steps:

[0016] Step S11: Obtain unit operating parameters through the distributed control system of the unit. The obtained parameters include AGC load commands issued by the grid dispatch center. Actual power generation of the unit Steam turbine exhaust pressure Inlet circulating water temperature of the indirect cooling tower Ambient temperature Ambient relative humidity Current operating frequency of the sprinkler pump and the fuel quantity command output by the boiler main control. ;

[0017] Step S12: Perform bad value limiting and first-order low-pass filtering on the original signal obtained in step S11 to filter out high-frequency noise. The filtering time constant is 0.5 seconds.

[0018] Furthermore, step S2 includes the following steps:

[0019] Step S21: Calculate power deviation in real time When both conditions are met and When a significant step or continuous ramp-up occurs in the AGC command and the boiler response lags, the delay compensation logic is triggered; whereby... The AGC adjustment dead zone is set at 0.3% of the unit's rated power. The threshold is set based on the lower limit of the power grid AGC assessment rate;

[0020] Step S22: Record the current spray pump frequency at the moment of triggering as the reference frequency. And store the fuel quantity commands from the 10 minutes prior to triggering. Compared with actual power The historical sequence is used for subsequent online model identification.

[0021] Furthermore, step S3 includes the following steps:

[0022] Step S31: Construct the nominal response model of the boiler The nominal boiler response model is used to describe the slow dynamic characteristics of the boiler from the change of fuel quantity command to the unit's electrical power output. It is in the form of a first-order inertial plus pure time delay transfer function, which can predict the power following trajectory of the boiler without spray intervention in subsequent steps. The calculation formula is:

[0023] ;

[0024] In the formula, The static gain of the boiler response is calculated by applying the steady-state relationship between fuel quantity and power and the boiler heat storage coefficient. This is the pure time delay; The inertial time constant; For the Laplace operator;

[0025] Step S32: Utilize the fuel quantity command in the pre-trigger window As input, actual generated power As output, the pure time delay is identified online using the augmented recursive least squares algorithm with an exponential forgetting factor. and inertial time constant .

[0026] Furthermore, step S4 includes the following steps:

[0027] Step S41: Transfer AGC load command Input the boiler nominal model identified in step S3 Generate the boiler's estimated power response The estimated power response of the boiler Used to reflect the power following value that the boiler can achieve due to inertia and lag under the assumption of no spray intervention, and as a benchmark for difference calculation; The iterative calculation method is as follows:

[0028] ;

[0029] Step S42: By passing the AGC load command Boiler Estimated Power Response Calculate the difference to generate power compensation requirements. The power compensation requirement Used to quantify the power deficit that cannot be provided temporarily due to boiler response lag, as the power target value that the rapid compensation device needs to undertake; The calculation method is as follows:

[0030] ;

[0031] In the formula, The value represents the power compensation amount that varies over time. A positive value indicates that the boiler output is lagging and the spray system needs to provide positive power compensation, while a negative value indicates that the boiler has started to over-adjust and the spray compensation needs to be withdrawn in a timely manner.

[0032] Furthermore, step S5 includes the following steps:

[0033] Step S51: Construct the exhaust pressure slight increase output coefficient The slight increase in exhaust pressure and output coefficient It is used to quantify the change in electrical power caused by a unit change in exhaust pressure, and to provide a basis for the conversion of power demand into pressure regulation command; The calculation method is as follows:

[0034] ;

[0035] In the formula, Always negative; The value depends on the current unit load. With exhaust pressure Based on the variable operating condition characteristic curve of the last stage of the low-pressure cylinder provided by the manufacturer and corrected by high-precision thermodynamic tests on site, a two-dimensional interpolation table is generated. The data is obtained online via table lookup within the control period;

[0036] Step S52: The change in exhaust pressure setpoint is generated by dividing the power compensation requirement by the exhaust pressure increment output coefficient and then inverting the result. The change in the exhaust pressure setpoint Used to convert power deficit into pressure regulation target commands on the air-cooled system side; The calculation method is as follows:

[0037] ;

[0038] In the formula, the negative reciprocal relationship ensures that positive power compensation corresponds to a decrease in exhaust pressure, i.e., the direction of enhanced spraying.

[0039] Furthermore, step S6 includes the following steps:

[0040] Step S61: Construct the spray frequency-exhaust steam pressure increment transfer function The spray frequency-exhaust steam pressure increment transfer function It is used to describe the forward dynamic process of the spray pump frequency change to the exhaust steam pressure response, and provides an object description for the inverse model; The expression is:

[0041] ;

[0042] In the formula, A negative gain indicates the static capability of reducing exhaust pressure as the frequency increases. The inertial time constant for evaporative cooling and circulating water temperature changes; and Using the small natural fluctuation data of the spray frequency during the current period when it is not compensated for, the data is updated in real time through the recursive augmented least squares algorithm.

[0043] Step S62: Generate the feedforward spray frequency increment by inverting the transfer function of spray frequency-exhaust pressure increment and applying it to the change in exhaust pressure setpoint. The feedforward spray frequency increment Used to output frequency compensation with phase lead characteristics to overcome the inertial delay of air-cooled towers and enable the exhaust pressure to quickly track set changes. The calculation method is as follows:

[0044] ;

[0045] In the formula, Used for phase lead to compensate for inertial delay. Used for static gain matching; during calculation, first... Implement low-pass filtering, with the filtering time constant set to... Then, the numerical derivative is calculated to suppress high-frequency noise amplification.

[0046] Furthermore, step S7 includes the following steps:

[0047] Step S71: Execute the frequency range limit for the spray pump inverter, and set the final command frequency. Limited to the minimum safe frequency With the rated frequency of the water pump between;

[0048] Step S72: Perform a safety limit check on the exhaust pressure of the air-cooled tube bundle. Based on the transfer function in step S61, predict the exhaust pressure response after frequency changes. If the predicted value may exceed the safety limit of the back pressure of the air-cooled system... or lower limit Then reduce according to the principle of proportionality. ;

[0049] Step S73: Implement exhaust pressure change rate limit, enforce constraint Among them, the maximum permissible limit for the rate of change of exhaust steam pressure. The frequency command is determined based on the life curve of the last stage blades of the steam turbine; after the above constraint processing. Instantly write to the frequency converter of the spray pump to perform rapid back pressure regulation.

[0050] Furthermore, step S8 includes the following steps:

[0051] Step S81: Continuously monitor AGC load commands Boiler Estimated Power Response The degree of closeness, when simultaneously satisfying the condition for 30 consecutive seconds And the measured power deviation When the exit condition is met, it is determined that the exit condition is satisfied.

[0052] Step S82: The exit process prohibits step recovery, and the current spray frequency command is changed at a fixed rate. Gradually decay to the pre-trigger reference frequency ,in, Pick 1 / 3 of.

[0053] Furthermore, in step S81, monitoring continues during the exit period. If the power deviation exceeds the dead zone again, the exit process will be terminated and the compensation logic calculation will be resumed immediately. The exit countdown will be restarted after the power stabilizes again.

[0054] The present invention has the following beneficial effects:

[0055] 1. This invention utilizes the existing variable frequency spray system of the indirect air-cooled tower as an independent rapid power compensation resource. By decoupling the pure lag and inertia of the boiler combustion response, it generates active positive power support in the early stage of AGC command changes, effectively shortening the delay in the actual power of the unit following the dispatch command, improving the loss of integral power assessment caused by the slow response on the boiler side, and enhancing the regulation performance of thermal power units in the ancillary service market.

[0056] 2. This invention adopts a feedforward calculation method based on the turbine exhaust pressure slight increase output coefficient and the air-cooled tower spray inverse model, which directly converts the power compensation demand into spray frequency command, avoiding the lag and oscillation of conventional feedback regulation. This allows the exhaust pressure adjustment to act on the unit output in a leading phase, thereby achieving precise delay power deficit cancellation without significantly changing the condensate system or turbine control valve design.

[0057] 3. By identifying the nominal response model of the boiler and the spray frequency-exhaust pressure transfer function online, the control parameters can be adaptively updated according to changes in operating conditions such as coal mill combination, fuel characteristics, and ambient temperature and humidity. This ensures that the compensation logic can be stably matched across the entire operating range, avoiding the problem of large deviations in compensation amount under non-design conditions caused by fixed parameter control strategies.

[0058] 4. The multi-constraint verification mechanism of this invention incorporates the frequency range of the spray pump, the safety boundary of the exhaust pressure of the air-cooled tube bundle, and the allowable stress rate limit of the last stage blade of the steam turbine into the command generation process. While performing rapid back pressure regulation, it prevents the equipment operating parameters from exceeding the limit and the thermal fatigue damage of components, so that the compensation process will not sacrifice operational safety and equipment life in pursuit of response speed.

[0059] 5. The present invention adopts a smooth attenuation and status monitoring closed loop for compensation exit. The spray frequency command gradually returns to the reference value after the boiler output recovers. During the exit process, the power deviation is continuously judged. Once the deviation exceeds the limit again, compensation is restored, avoiding secondary power disturbances caused by step exit and realizing a seamless connection between rapid compensation and conventional adjustment.

[0060] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying 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.

[0062] Figure 1 This is a flowchart illustrating an AGC response delay compensation control method for thermal power units according to the present invention. Detailed Implementation

[0063] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] Please see Figure 1 As shown, this invention provides an AGC response delay compensation control method for thermal power units, comprising the following steps:

[0065] Step S1: Collect unit operating parameters and perform preprocessing;

[0066] Step S2: Based on the power deviation between the AGC load command and the actual generated power, as well as the command change rate, trigger the delay compensation logic and record the reference frequency and historical data of the sprinkler pump.

[0067] Step S3: Using the fuel quantity command and actual power generation data in the pre-trigger window, identify the nominal boiler response model online;

[0068] Step S4: Input the AGC load command into the nominal boiler response model to generate the estimated boiler power response, and calculate the difference between the AGC load command and the estimated boiler power response to generate the power compensation demand;

[0069] Step S5: Based on the characteristics of the turbine's slight increase in output, the power compensation requirement is converted into the change in the exhaust pressure setpoint.

[0070] Step S6: Construct the spray frequency-exhaust pressure increment transfer function, invert the transfer function and apply it to the change in exhaust pressure setpoint to generate the feedforward spray frequency increment;

[0071] Step S7: Perform multiple constraint checks on the feedforward spray frequency increment to obtain the final spray frequency command and issue it for execution;

[0072] Step S8: Monitor the proximity between the AGC load command and the boiler's estimated power response, as well as the deviation of the measured power. When the exit conditions are met, reduce the spray frequency command to the reference frequency at a fixed rate, and continuously monitor the power deviation during the exit period to determine whether to restore compensation.

[0073] Step S1 includes the following steps:

[0074] Step S11: Obtain unit operating parameters through the distributed control system of the unit. The obtained parameters include AGC load commands issued by the grid dispatch center. Actual power generation of the unit Steam turbine exhaust pressure Inlet circulating water temperature of the indirect cooling tower Ambient temperature Ambient relative humidity Current operating frequency of the sprinkler pump and the fuel quantity command output by the boiler main control. ;

[0075] Step S12: Perform bad value limiting and first-order low-pass filtering on the original signal obtained in step S11 to filter out high-frequency noise. The filtering time constant is 0.5 seconds.

[0076] Step S2 includes the following steps:

[0077] Step S21: Calculate power deviation in real time When both conditions are met and When a significant step or continuous ramp-up occurs in the AGC command and the boiler response lags, the delay compensation logic is triggered; whereby... The AGC adjustment dead zone is set at 0.3% of the unit's rated power. The threshold is set based on the lower limit of the power grid AGC assessment rate;

[0078] Step S22: Record the current spray pump frequency at the moment of triggering as the reference frequency. And store the fuel quantity commands from the 10 minutes prior to triggering. Compared with actual power The historical sequence is used for subsequent online model identification.

[0079] Step S3 includes the following steps:

[0080] Step S31: Construct the nominal response model of the boiler The nominal response model of the boiler is used to describe the slow dynamic characteristics of the boiler from the change of fuel quantity command to the unit's electrical power output. It is in the form of a first-order inertial plus pure time delay transfer function, which can predict the power following trajectory of the boiler without spray intervention in subsequent steps. The calculation formula is:

[0081] ;

[0082] In the formula, The static gain of the boiler response is calculated by applying the steady-state relationship between fuel quantity and power and the boiler heat storage coefficient. This is the pure time delay; The inertial time constant; For the Laplace operator;

[0083] Step S32: Utilize the fuel quantity command in the pre-trigger window As input, actual generated power As output, the pure time delay is identified online using the augmented recursive least squares algorithm with an exponential forgetting factor. and inertial time constant .

[0084] Step S4 includes the following steps:

[0085] Step S41: Transfer AGC load command Input the boiler nominal model identified in step S3 Generate the boiler's estimated power response Boiler Estimated Power Response Used to reflect the power following value that the boiler can achieve due to inertia and lag under the assumption of no spray intervention, and as a benchmark for difference calculation; The iterative calculation method is as follows:

[0086] ;

[0087] Step S42: By passing the AGC load command Boiler Estimated Power Response Calculate the difference to generate power compensation requirements. Power compensation requirements Used to quantify the power deficit that cannot be provided temporarily due to boiler response lag, as the power target value that the rapid compensation device needs to undertake; The calculation method is as follows:

[0088] ;

[0089] In the formula, The value represents the power compensation amount that varies over time. A positive value indicates that the boiler output is lagging and the spray system needs to provide positive power compensation, while a negative value indicates that the boiler has started to over-adjust and the spray compensation needs to be withdrawn in a timely manner.

[0090] Step S5 includes the following steps:

[0091] Step S51: Construct the exhaust pressure slight increase output coefficient Slight increase in exhaust pressure and output coefficient It is used to quantify the change in electrical power caused by a unit change in exhaust pressure, and to provide a basis for the conversion of power demand into pressure regulation command; The calculation method is as follows:

[0092] ;

[0093] In the formula, Always negative; The value depends on the current unit load. With exhaust pressure Based on the variable operating condition characteristic curve of the last stage of the low-pressure cylinder provided by the manufacturer and corrected by high-precision thermodynamic tests on site, a two-dimensional interpolation table is generated. The data is obtained online via table lookup within the control period;

[0094] Step S52: The change in exhaust pressure setpoint is generated by dividing the power compensation requirement by the exhaust pressure increment output coefficient and then inverting the result. Change in exhaust pressure setpoint Used to convert power deficit into pressure regulation target commands on the air-cooled system side; The calculation method is as follows:

[0095] ;

[0096] In the formula, the negative reciprocal relationship ensures that positive power compensation corresponds to a decrease in exhaust pressure, i.e., the direction of enhanced spraying.

[0097] Step S6 includes the following steps:

[0098] Step S61: Construct the spray frequency-exhaust steam pressure increment transfer function Spray frequency-exhaust steam pressure increment transfer function It is used to describe the forward dynamic process of the spray pump frequency change to the exhaust steam pressure response, and provides an object description for the inverse model; The expression is:

[0099] ;

[0100] In the formula, A negative gain indicates the static capability of reducing exhaust pressure as the frequency increases. The inertial time constant for evaporative cooling and circulating water temperature changes; and Using the small natural fluctuation data of the spray frequency during the current period when it is not compensated for, the data is updated in real time through the recursive augmented least squares algorithm.

[0101] Step S62: Generate the feedforward spray frequency increment by inverting the transfer function of spray frequency-exhaust pressure increment and applying it to the change in exhaust pressure setpoint. Feedforward spray frequency increment Used to output frequency compensation with phase lead characteristics to overcome the inertial delay of air-cooled towers and enable the exhaust pressure to quickly track set changes. The calculation method is as follows:

[0102] ;

[0103] In the formula, Used for phase lead to compensate for inertial delay. Used for static gain matching; during calculation, first... Implement low-pass filtering, with the filtering time constant set to... Then, the numerical derivative is calculated to suppress high-frequency noise amplification.

[0104] Step S7 includes the following steps:

[0105] Step S71: Execute the frequency range limit for the spray pump inverter, and set the final command frequency. Limited to the minimum safe frequency With the rated frequency of the water pump between;

[0106] Step S72: Perform a safety limit check on the exhaust pressure of the air-cooled tube bundle. Based on the transfer function in step S61, predict the exhaust pressure response after frequency changes. If the predicted value may exceed the safety limit of the back pressure of the air-cooled system... or lower limit Then reduce according to the principle of proportionality. ;

[0107] Step S73: Implement exhaust pressure change rate limit, enforce constraint Among them, the maximum permissible limit for the rate of change of exhaust steam pressure. The frequency command is determined based on the life curve of the last stage blades of the steam turbine; after the above constraint processing. Instantly write to the frequency converter of the spray pump to perform rapid back pressure regulation.

[0108] Step S8 includes the following steps:

[0109] Step S81: Continuously monitor AGC load commands Boiler Estimated Power Response The degree of closeness, when simultaneously satisfying the condition for 30 consecutive seconds And the measured power deviation When the exit condition is met, it is determined that the exit condition is satisfied.

[0110] Step S82: The exit process prohibits step recovery, and the current spray frequency command is changed at a fixed rate. Gradually decay to the pre-trigger reference frequency ,in, Pick 1 / 3 of.

[0111] In step S81, monitoring continues during the exit period. If the power deviation exceeds the dead zone again, the exit process will be terminated and the compensation logic calculation will be resumed immediately. The exit countdown will be restarted after the power stabilizes again.

[0112] One specific application of this embodiment is:

[0113] This embodiment discloses an AGC response delay compensation control method for thermal power units, applied to a 300MW indirect air-cooled condensing thermal power unit. The unit is equipped with an indirect cooling tower variable frequency spray system, with a rated spray pump frequency of 50Hz and a minimum safe operating frequency of 10Hz. The turbine's rated back pressure is 12kPa, and the safe operating range of back pressure is 5kPa to 25kPa. The grid AGC regulation dead zone is 0.3% of the unit's rated power (i.e., 0.9MW), and the lower limit of the grid AGC assessment rate is 2% of the rated power per minute (i.e., 6MW / min). The specific implementation steps of this embodiment are as follows:

[0114] Step S1: Collect unit operating parameters and perform preprocessing

[0115] Step S11: Collect runtime parameters

[0116] The unit's operating parameters are collected in real time through the distributed control system (DCS), with a sampling period set to 200ms. The collected parameters include:

[0117] AGC load instructions issued by the power grid dispatch center ;

[0118] Actual power generation of the unit ;

[0119] Steam turbine exhaust pressure ;

[0120] Inlet circulating water temperature of the indirect cooling tower ;

[0121] Ambient temperature ;

[0122] Ambient relative humidity ;

[0123] Current operating frequency of the sprinkler pump ;

[0124] Fuel quantity command output by boiler main control ;

[0125] Step S12: Signal preprocessing

[0126] The raw signal obtained in step S11 is subjected to outlier limiting and first-order low-pass filtering to remove high-frequency noise. Outlier limiting uses the 3σ criterion to eliminate outliers, and the transfer function of the first-order low-pass filter is:

[0127] ;

[0128] In the formula, the filtering time constant , For the Laplace operator.

[0129] Step S2: Trigger the delay compensation logic and record the reference frequency and historical data.

[0130] Step S21: Triggering the compensation logic

[0131] Real-time calculation of the power deviation between AGC load commands and actual generated power. The calculation formula is:

[0132] ;

[0133] When both conditions are met and When the AGC command is determined to have a significant step or continuous ramp-up and the boiler response is delayed, the delay compensation logic is triggered.

[0134] In this embodiment, The dead zone for AGC adjustment is set at 0.3% of the unit's rated power. ; To take the threshold set according to the lower limit of the power grid AGC assessment rate, .

[0135] The triggering scenario in this embodiment is: the AGC load command jumps from 200MW to 240MW, with an initial power deviation. Command change rate Once the triggering conditions are met, the delay compensation logic is officially triggered.

[0136] Step S22: Baseline parameters and historical data storage

[0137] The current frequency of the sprinkler pump is recorded at the moment of triggering and used as the reference frequency. In this embodiment, the instantaneous operating frequency of the sprinkler pump is 25Hz, i.e. Simultaneously store the fuel quantity commands from the 10 minutes prior to triggering. Compared with actual power The historical sequence, with a sampling interval of 1 second, totaled 600 sets of data, which were used for subsequent online model identification.

[0138] Step S3: Online identification of the nominal model of boiler response

[0139] Step S31: Construction of Boiler Nominal Response Model

[0140] Constructing a nominal response model for boilers This describes the slow dynamic characteristics of a boiler from a change in fuel quantity command to the unit's electrical power output. It takes the form of a first-order inertial plus pure time-delay transfer function, expressed as:

[0141] ;

[0142] In the formula: The static gain of the boiler response is calculated in this embodiment using the steady-state relationship between fuel quantity and power and the boiler heat storage coefficient. ;

[0143] The time delay is the pure time lag, measured in seconds (s).

[0144] The inertial time constant is expressed in seconds (s).

[0145] For the Laplace operator.

[0146] Step S32: Online identification of model parameters

[0147] Utilize the fuel quantity command within the 10-minute window prior to triggering As input, actual generated power As output, an augmented recursive least squares algorithm with an exponential forgetting factor is used for online identification. In this embodiment, the forgetting factor is set to 0.98, and the pure time delay is finally identified. Inertial time constant .

[0148] Step S4: Generate the estimated power response and power compensation requirements for the boiler.

[0149] Step S41: Boiler Estimated Power Response Calculation

[0150] AGC load command Input the boiler nominal model identified in step S3 Generate the boiler's estimated power response The differential equation for its iterative calculation is:

[0151] ;

[0152] In this embodiment, substitution , , Discretized iterative calculations were performed using the forward Euler method, with the step size consistent with the control period at 200 ms, to obtain the power following trajectory of the boiler without spray intervention. .

[0153] Step S42: Calculation of power compensation requirements

[0154] via AGC load command Boiler Estimated Power Response Calculate the difference to generate power compensation requirements. The calculation formula is:

[0155] ;

[0156] In the formula, The value represents the power compensation amount that varies over time. A positive value indicates that the boiler output is lagging and the spray system needs to provide positive power compensation, while a negative value indicates that the boiler has started to over-adjust and the spray compensation needs to be withdrawn in a timely manner.

[0157] In this embodiment, the calculation is performed 5 seconds after the instruction step. This means that the sprinkler system needs to provide 32.5MW of positive power compensation.

[0158] Step S5: Convert the power compensation requirement into the change in exhaust pressure setpoint.

[0159] Step S51: Slight increase in exhaust pressure and construction of output coefficient

[0160] Constructing a slight increase in exhaust pressure output coefficient This is used to quantify the change in electrical power caused by a unit change in exhaust steam pressure, and its definition is:

[0161] ;

[0162] In the formula, The value is always negative. In this embodiment, the characteristic curve of the last stage of the low-pressure cylinder under variable operating conditions provided by the turbine manufacturer is corrected by high-precision thermodynamic testing on site to form a value based on the actual power output of the unit. Exhaust pressure Two-dimensional interpolation table for independent variables The value is obtained online by looking up a table within each 200ms control cycle.

[0163] In this embodiment, the current load of the unit after the command step jump Exhaust pressure The table can be consulted to obtain the result. That is, for every 1 kPa decrease in exhaust steam pressure, the actual power output of the unit can be increased by 8.2 MW.

[0164] Step S52: Calculation of the change in exhaust pressure setpoint

[0165] The change in exhaust pressure setpoint is generated by dividing the power compensation requirement by the exhaust pressure increment output coefficient and then inverting the result. The calculation formula is:

[0166] In the formula, the negative reciprocal relationship ensures that the positive power compensation corresponds to the reduction of exhaust pressure, i.e. the direction of spray enhancement.

[0167] In this embodiment, substitution , The calculation yields:

[0168] ;

[0169] This means that the exhaust pressure setpoint needs to be reduced by 3.96 kPa to achieve a power compensation of 32.5 MW.

[0170] Step S6: Generate feedforward spray frequency increment

[0171] Step S61: Construction of the spray frequency-exhaust pressure increment transfer function

[0172] Constructing the spray frequency-exhaust steam pressure increment transfer function This describes the positive dynamic process of the spray pump frequency changing to the exhaust steam pressure response, and its expression is:

[0173] ;

[0174] In the formula: Negative gain indicates the static capability of reducing exhaust pressure as frequency increases, measured in units of... ;

[0175] This is the inertial time constant for evaporative cooling and circulating water temperature changes, expressed in seconds.

[0176] In this embodiment, the small natural fluctuation data of the spray frequency during the uncompensated adjustment within the current time period are used to update the data in real time through a recursive augmented least squares algorithm, ultimately identifying the data. , That is, for every 1 Hz increase in the frequency of the spray pump, the steady-state exhaust pressure decreases by 0.32 kPa.

[0177] Step S62: Calculation of feedforward spray frequency increment

[0178] Transfer function of spray frequency-exhaust pressure increment Inverse the equation and apply it to the change in exhaust pressure setpoint. Generate feedforward spray frequency increment Its time-domain calculation formula is:

[0179] ;

[0180] In the formula, The term is used for phase lead to compensate for inertial delay. This term is used for static gain matching.

[0181] During the calculation, first... Implement low-pass filtering, with the filtering time constant set to... Then, the numerical derivative is calculated to suppress high-frequency noise amplification.

[0182] In this embodiment, substitution , , The initial differential term of the step instruction is taken as 0.21 kPa / s, and the calculation yields:

[0183] ;

[0184] The negative sign indicates that the spray frequency needs to be increased by 20.25Hz from the base frequency in order to achieve a rapid reduction in exhaust pressure.

[0185] Step S7: Multi-constraint verification and instruction issuance and execution

[0186] Step S71: Spray pump frequency range limitation

[0187] The initial formula for calculating the final instruction frequency is:

[0188] ;

[0189] In this embodiment, , Initial calculations yielded Limit it to the lowest safe frequency. With the rated frequency of the water pump In this embodiment, 45.25Hz is within a safe range and does not require amplitude limiting.

[0190] Step S72: Exhaust pressure safety limit check

[0191] Based on the transfer function in step S61 Predicting the exhaust pressure response after frequency changes, the back pressure safe operating range in this embodiment is: ~ The predicted steady-state value of the exhaust pressure after the frequency is increased to 45.25Hz is... It is within a safe range and does not require reduction. If the predicted value exceeds the upper and lower safety limits, the feedforward increment will be reduced proportionally.

[0192] Step S73: Frequency Change Rate Limitation and Command Issuance

[0193] The forced constraint rate of frequency change must satisfy:

[0194] ;

[0195] In this embodiment, the maximum permissible frequency variation rate is determined based on the life curve of the last stage blade of the steam turbine. In this embodiment, the calculated frequency change rate is 2.5 Hz / s, which meets the limit requirements; the frequency command after the above triple constraint processing The data is immediately written to the frequency converter of the spray pump to perform rapid back pressure regulation.

[0196] Step S8: Exit the compensation logic and perform closed-loop monitoring

[0197] Step S81: Exit condition determination and anomaly monitoring

[0198] Continuous monitoring of AGC load commands Boiler Estimated Power Response The degree of closeness, when simultaneously satisfying the condition for 30 consecutive seconds And the measured power deviation When the exit condition is met, it is determined that the exit condition is satisfied.

[0199] In this embodiment, Take 0.2% of the unit's rated power, that is , 142 seconds after the command step, the unit's actual power output stabilized at 239.5MW, and the boiler's estimated power response... Satisfying the requirement for 30 consecutive seconds ,and The exit conditions have been met.

[0200] Continuous monitoring during exit If the power deviation exceeds the dead zone again If the power level stabilizes again, the exit process will be terminated and the compensation logic calculation will be resumed immediately. The exit countdown will be restarted after the power level stabilizes again.

[0201] Step S82: Smoothly exit control

[0202] The exit process prohibits step recovery and will switch the current spray frequency command at a fixed rate. Gradually decay to the pre-trigger reference frequency In this embodiment Pick 1 / 3, that is The spray frequency gradually decreases from 45.25Hz to 25Hz at a rate of 1.67Hz / s without any step change, avoiding secondary power disturbances and achieving seamless connection between the compensation logic and conventional back pressure control.

[0203] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0204] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for compensating AGC response delay in thermal power units, characterized in that, Includes the following steps: Step S1: Collect unit operating parameters and perform preprocessing; Step S2: Based on the power deviation between the AGC load command and the actual generated power, as well as the command change rate, trigger the delay compensation logic and record the reference frequency and historical data of the sprinkler pump. Step S3: Using the fuel quantity command and actual power generation data in the pre-trigger window, identify the nominal boiler response model online; Step S4: Input the AGC load command into the nominal boiler response model to generate the estimated boiler power response, and calculate the difference between the AGC load command and the estimated boiler power response to generate the power compensation demand; Step S5: Based on the characteristics of the turbine's slight increase in output, the power compensation requirement is converted into the change in the exhaust pressure setpoint. Step S6: Construct the spray frequency-exhaust pressure increment transfer function, invert the transfer function and apply it to the change in exhaust pressure setpoint to generate the feedforward spray frequency increment; Step S7: Perform multiple constraint checks on the feedforward spray frequency increment to obtain the final spray frequency command and issue it for execution; Step S8: Monitor the proximity between the AGC load command and the boiler's estimated power response, as well as the deviation of the measured power. When the exit conditions are met, reduce the spray frequency command to the reference frequency at a fixed rate, and continuously monitor the power deviation during the exit period to determine whether to restore compensation.

2. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Obtain unit operating parameters through the distributed control system of the unit. The obtained parameters include AGC load commands issued by the grid dispatch center. Actual power generation of the unit Steam turbine exhaust pressure Inlet circulating water temperature of the indirect cooling tower Ambient temperature Ambient relative humidity Current operating frequency of the sprinkler pump and the fuel quantity command output by the boiler main control. ; Step S12: Perform bad value limiting and first-order low-pass filtering on the original signal obtained in step S11 to filter out high-frequency noise.

3. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Calculate power deviation in real time When both conditions are met and When a significant step or continuous ramp-up occurs in the AGC command and the boiler response lags, the delay compensation logic is triggered; among which, Adjust the dead zone for AGC. The threshold is set based on the lower limit of the power grid AGC assessment rate; Step S22: Record the current spray pump frequency at the moment of triggering as the reference frequency. And store the fuel quantity commands from the 10 minutes prior to triggering. Compared with actual power The historical sequence is used for subsequent online model identification.

4. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: Construct the nominal response model of the boiler The nominal boiler response model is used to describe the slow dynamic characteristics of the boiler from the change of fuel quantity command to the unit's electrical power output. It is in the form of a first-order inertial plus pure time delay transfer function, which can predict the power following trajectory of the boiler without spray intervention in subsequent steps. The calculation formula is: ， In the formula, The static gain of the boiler response is calculated by applying the steady-state relationship between fuel quantity and power and the boiler heat storage coefficient. This is the pure time delay; The inertial time constant; For the Laplace operator; Step S32: Utilize the fuel quantity command in the pre-trigger window As input, actual generated power As output, the pure time delay is identified online using the augmented recursive least squares algorithm with an exponential forgetting factor. and inertial time constant .

5. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S4 includes the following steps: Step S41: Transfer AGC load command Input the boiler nominal model identified in step S3 Generate the boiler's estimated power response The estimated power response of the boiler Used to reflect the power following value that the boiler can achieve due to inertia and lag under the assumption of no spray intervention, and as a benchmark for difference calculation; The iterative calculation method is as follows: ， Step S42: By passing the AGC load command Boiler Estimated Power Response Calculate the difference to generate power compensation requirements. The power compensation requirement Used to quantify the power deficit that cannot be provided temporarily due to boiler response lag, as the power target value that the rapid compensation device needs to undertake; The calculation method is as follows: ， In the formula, The value represents the power compensation amount that varies over time. A positive value indicates that the boiler output is lagging and the spray system needs to provide positive power compensation, while a negative value indicates that the boiler has started to over-adjust and the spray compensation needs to be withdrawn in a timely manner.

6. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S5 includes the following steps: Step S51: Construct the exhaust pressure slight increase output coefficient The slight increase in exhaust pressure and output coefficient It is used to quantify the change in electrical power caused by a unit change in exhaust pressure, and to provide a basis for the conversion of power demand into pressure regulation command; The calculation method is as follows: ， In the formula, Always negative; The value depends on the current unit load. With exhaust pressure Based on the variable operating condition characteristic curve of the last stage of the low-pressure cylinder provided by the manufacturer and corrected by high-precision thermodynamic tests on site, a two-dimensional interpolation table is generated. The data is obtained online via table lookup within the control period; Step S52: The change in exhaust pressure setpoint is generated by dividing the power compensation requirement by the exhaust pressure increment output coefficient and then inverting the result. The change in the exhaust pressure setpoint Used to convert power deficit into pressure regulation target commands on the air-cooled system side; The calculation method is as follows: ， In the formula, the negative reciprocal relationship ensures that positive power compensation corresponds to a decrease in exhaust pressure, i.e., the direction of enhanced spraying.

7. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S6 includes the following steps: Step S61: Construct the spray frequency-exhaust steam pressure increment transfer function The spray frequency-exhaust steam pressure increment transfer function It is used to describe the forward dynamic process of the spray pump frequency change to the exhaust steam pressure response, and provides an object description for the inverse model; The expression is: ， In the formula, A negative gain indicates the static capability of reducing exhaust pressure as the frequency increases. The inertial time constant for evaporative cooling and circulating water temperature changes; and Using the small natural fluctuation data of the spray frequency during the current period when it is not compensated for, the data is updated in real time through the recursive augmented least squares algorithm. Step S62: Generate the feedforward spray frequency increment by inverting the transfer function of spray frequency-exhaust pressure increment and applying it to the change in exhaust pressure setpoint. The feedforward spray frequency increment Used to output frequency compensation with phase lead characteristics to overcome the inertial delay of air-cooled towers and enable the exhaust pressure to quickly track set changes. The calculation method is as follows: ， In the formula, Used for phase lead to compensate for inertial delay. Used for static gain matching; during calculation, first... Implement low-pass filtering, with the filtering time constant set to... Then, the numerical derivative is calculated to suppress high-frequency noise amplification.

8. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S7 includes the following steps: Step S71: Execute the frequency range limit for the spray pump inverter, and set the final command frequency. Limited to the minimum safe frequency With the rated frequency of the water pump between; Step S72: Perform a safety limit check on the exhaust pressure of the air-cooled tube bundle. Based on the transfer function in step S61, predict the exhaust pressure response after frequency changes. If the predicted value may exceed the safety limit of the back pressure of the air-cooled system... or lower limit Then reduce according to the principle of proportionality. ; Step S73: Implement exhaust pressure change rate limit, enforce constraint Among them, the maximum permissible limit for the rate of change of exhaust steam pressure. The frequency command is determined based on the life curve of the last stage blades of the steam turbine; after the above constraint processing. Instantly write to the frequency converter of the spray pump to perform rapid back pressure regulation.

9. The AGC response delay compensation control method for thermal power units according to claim 1, characterized in that, Step S8 includes the following steps: Step S81: Continuously monitor AGC load commands Boiler Estimated Power Response The degree of closeness, when simultaneously satisfying the condition for 30 consecutive seconds And the measured power deviation When the exit condition is met, it is determined that the exit condition is satisfied. Step S82: The exit process prohibits step recovery, and the current spray frequency command is changed at a fixed rate. Gradually decay to the pre-trigger reference frequency ,in, Pick 1 / 3 of.

10. The AGC response delay compensation control method for thermal power units according to claim 9, characterized in that, In step S81, monitoring continues during the exit period. If the power deviation exceeds the dead zone again, the exit process will be terminated and the compensation logic calculation will be resumed immediately. The exit countdown will be restarted after the power stabilizes again.

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