Coordinated control systems and methods for thermal power plant units, thermal power plant units and media

Abstract

This invention discloses a coordinated control system, method, unit, and medium for thermal power plant units. The system includes: a unit control command module for acquiring initial unit control signals and target unit control signals; a load change determination module for determining the change in control signals based on the initial and target unit control signals and generating a first control signal; a reference lag module for outputting the target unit control signal lagging behind the formation time of the boiler coal quantity command; a high-selection module for outputting the larger value between the unit control signal and the first control signal; and an air-coal ratio function module for generating a boiler air quantity command based on the larger value between the unit control signal and the first control signal. The boiler coal quantity command is obtained through PID calculation, and the time of generating the boiler air quantity command based on the first control signal is earlier than the formation time of the boiler coal quantity command. The coordinated control system of this invention enables better performance in rapid start-up and shutdown and rapid load increases and decreases.

Description

Technical Field

[0001] This invention relates to the field of power-related technologies, and in particular to a coordinated control system, method, thermal power plant unit, and medium for thermal power plant units. Background Technology

[0002] The core objective of domestic thermal power plant flexibility retrofitting is to fully respond to fluctuations in the power system and achieve three main goals: reducing minimum output, rapid start-up and shutdown, and rapid load scaling. Currently, conventional flexibility retrofitting of 660MW thermal power plant units to achieve deep peak shaving of 35%–100% of rated load is primarily accomplished by adding software logic configurations, such as adding the following logic:

[0003] (1) The output of the two coal feeders A and E at the bottom layer was set to a lower limit of 20t / h. When the fuel main control output is lower than 20, the load is locked down to ensure the combustion stability of the bottom layer.

[0004] (2) Plasma ignition is activated when the load is below 40%. Plasma ignition is beneficial to the stability of combustion in the furnace.

[0005] (3) When the load drops to 500MW, 330MW, and 280MW, the F, C, and D coal mills shall be shut down from top to bottom respectively. When the minimum load is 230MW, the three lower-level coal mills shall be kept running stably.

[0006] (4) When the load change is between 50% and 100%, the change rate is set to 10 MW / min. When the load change is between 30% and 50%, the load change rate is changed to 7.3 MW / min.

[0007] (5) Boiler main control variable load feedforward optimization.

[0008] However, the above measures do not achieve the desired effect of rapid start-up and rapid load increase / decrease in the deep peak shaving of the coordinated control configuration. Summary of the Invention

[0009] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a coordinated control system for thermal power plant units, which enables better performance in rapid start-up and shutdown, and rapid load increases and decreases.

[0010] The present invention also provides a coordinated control method for thermal power plant units, thermal power plant units, control devices, and computer-readable storage media.

[0011] A coordinated control system for a thermal power plant unit according to a first aspect of the present invention includes:

[0012] The unit control command module is used to acquire unit control signals, which include initial unit control signals and target unit control signals after changes in unit load.

[0013] The load change determination module has a control signal input terminal and a control signal output terminal. The control signal input terminal is connected to the unit control command module. The load change determination module is used to determine the control signal change amount based on the initial unit control signal and the target unit control signal, and generate a first control signal based on the target unit control signal and the control signal change amount. When the control signal change amount is positive, the first control signal is greater than the target unit control signal; when the control signal change amount is negative, the first control signal is less than the target unit control signal.

[0014] The reference lag module has a lag input terminal and a lag output terminal. The lag input terminal is connected to the unit control command module. The reference lag module is used to output the target unit control signal with a lag time after the formation time of the boiler coal quantity command.

[0015] The high-selection module has a first input terminal, a second input terminal, and a high-selection output terminal. The first input terminal is connected to the hysteresis output terminal, and the second input terminal is connected to the control signal output terminal. The high-selection module is used to output the larger value between the target unit control signal and the first control signal.

[0016] The air-coal ratio function module has its input end connected to the high-selection output end. The air-coal ratio function module is used to generate a boiler air volume command based on the larger value between the target unit control signal and the first control signal. The boiler coal volume command is obtained through PID calculation, and the time of generating the boiler air volume command based on the first control signal is earlier than the time of forming the boiler coal volume command.

[0017] The coordinated control system for thermal power plant units according to embodiments of the present invention has at least the following beneficial effects:

[0018] The unit control command module outputs a target unit control signal after a change in unit load. The load change determination module determines the change in control signal before and after the load change and generates a first control signal. The reference lag module outputs the target unit control signal with a lag time to the formation time of the boiler coal quantity command. The high-selection module outputs the larger value between the target unit control signal and the first control signal. When the control signal change is positive, it indicates an increase in unit load. In this case, the first control signal is greater than the target unit control signal, and the time to generate the boiler airflow command directly based on the first control signal is shorter than the formation time of the boiler coal quantity command obtained through PID calculation. When the control signal change is negative, it indicates a decrease in unit load. In this case, the first control signal is less than the target unit control signal, and the boiler airflow command is generated based on the target unit control signal lagging behind the formation time of the boiler coal quantity command. This allows for the addition of airflow before coal when the unit load increases, and the reduction of coal before airflow when the unit load decreases, enabling rapid tracking of load change requirements and achieving coordinated and rapid load changes. The coordinated control system for thermal power plant units in this embodiment of the invention can improve the efficiency of rapid start-up and shutdown and rapid load increase / decrease.

[0019] According to some embodiments of the present invention, the load change determination module includes:

[0020] The first lag module has its input terminal connected to the unit control command module and is used to lag the output of the initial unit control signal.

[0021] The subtractor module has a first subtraction input terminal, a second subtraction input terminal, and a subtraction output terminal. The first subtraction input terminal is used to input the target unit control signal, and the second subtraction input terminal is connected to the output terminal of the first hysteresis module.

[0022] The first adder module has a first adder input terminal, a second adder input terminal, and a first adder output terminal. The first adder input terminal is used to input the target unit control signal. The second adder input terminal is connected to the subtraction output terminal, and the first adder output terminal is connected to the second adder input terminal.

[0023] According to some embodiments of the present invention, it further includes:

[0024] The variable load air volume feedforward module is used to output dynamic addition and subtraction, which is used to compensate for the air volume command delay caused by the time difference between the boiler and the turbine during variable load.

[0025] The second adder module has a third adder input terminal, a fourth adder input terminal, and a second adder output terminal. The third adder input terminal is connected to the output terminal of the air-coal ratio function module, and the fourth adder input terminal is connected to the variable load air volume feedforward module. The second adder module is used to compensate the boiler air volume command through the dynamic addition and subtraction to compensate for the air volume command delay caused by the time difference between the boiler and the turbine during variable load.

[0026] According to some embodiments of the present invention, the unit control command module includes:

[0027] The total fuel command module is used to output total fuel control signals;

[0028] The boiler main control command module is used to output boiler main control signals;

[0029] The conversion module has a first selection terminal, a second selection terminal, and a selection output terminal. The first selection terminal is connected to the total fuel command module, the second selection terminal is connected to the boiler main control command module, and the selection output terminal is connected to the control signal input terminal and the hysteresis input terminal respectively. The conversion module is used to select one of the total fuel control signal and the boiler main control signal as the unit control signal and output it through the selection output terminal.

[0030] According to some embodiments of the present invention, a linear module is further included between the boiler main control command module and the conversion module, the linear module being used to perform amplitude limiting processing on the unit control signal.

[0031] According to some embodiments of the present invention, a second hysteresis module is further included between the total fuel command module and the conversion module.

[0032] According to some embodiments of the present invention, a third hysteresis module is further included between the high-selection module and the air-coal ratio function module.

[0033] According to a second aspect of the present invention, a coordinated control method for a thermal power plant unit is applied to a coordinated control system for a thermal power plant unit as described in the first aspect of the present invention. The coordinated control method for the thermal power plant unit includes the following steps:

[0034] Acquire the initial unit control signal and the target unit control signal after the unit load changes;

[0035] The change in control signal is determined based on the initial unit control signal and the target unit control signal;

[0036] A first control signal is generated based on the target unit control signal and the change in the control signal. When the change in the control signal is positive, the first control signal is greater than the target unit control signal. When the change in the control signal is negative, the first control signal is less than the target unit control signal.

[0037] The air volume command generation strategy is executed according to the target unit control signal and the first control signal. The air volume command generation strategy includes a load increase strategy and a load decrease strategy. The load increase strategy includes the following steps: generating a boiler air volume command according to the first control signal, wherein the boiler coal quantity command is obtained through PID calculation, and the time of generating the boiler air volume command according to the first control signal is earlier than the formation time of the boiler coal quantity command. The load decrease strategy includes the following steps: generating a boiler air volume command according to the target unit control signal after the formation time of the boiler coal quantity command, so that when the unit increases the load, air volume is increased first and then coal is added, and when the unit decreases the load, coal is reduced first and then air volume is reduced.

[0038] The coordinated control method for thermal power plant units according to embodiments of the present invention has at least the following beneficial effects:

[0039] By determining the sign of the control signal change after a load change, the load increase or decrease can be identified. A positive control signal change indicates a load increase, and the time to generate the boiler air volume command directly from the first control signal is shorter than the time to generate the boiler coal volume command obtained through PID calculation. Conversely, a negative control signal change indicates a load decrease, and the boiler air volume command is generated based on the target unit control signal lagging behind the boiler coal volume command. This allows for the prioritization of air volume before coal volume during load increases and the prioritization of coal volume before air volume reduction during load decreases, enabling rapid tracking of load change requirements and achieving coordinated and rapid load changes. The coordinated control method for thermal power plant units in this embodiment of the invention improves the effectiveness of rapid start-up and shutdown and rapid load increases and decreases.

[0040] According to some embodiments of the present invention, the step of executing the air volume command generation strategy based on the target unit control signal and the first control signal includes the following steps:

[0041] If the target unit control signal is less than the first control signal, the load increase strategy is executed.

[0042] If the target unit control signal is greater than the first control signal, the load reduction strategy is executed.

[0043] According to some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0044] In response to the mill start-up configuration signal, the preset mill start-up coal feed rate and preset mill start-up water feed rate are increased. The mill start-up configuration signal is used to characterize the start-up of the coal mill and the coal feeder.

[0045] In response to the mill shutdown configuration signal, the preset mill shutdown coal feed rate and preset mill shutdown water feed rate are reduced. The mill shutdown configuration signal is used to indicate that the coal mill or coal feeder has stopped working.

[0046] According to some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0047] Obtain the actual generator power of the unit;

[0048] A variable load feedforward common command is generated based on the preset target generator power and the actual generator power of the unit to correct the power deviation between the actual generator power and the target generator power.

[0049] According to some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0050] Obtain the actual main steam pressure of the unit;

[0051] Based on the preset target main steam pressure and the actual main steam pressure of the unit, a variable load feedforward common command is generated to correct the main steam pressure deviation between the actual main steam pressure and the target main steam pressure of the unit.

[0052] According to some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0053] Obtain the real-time actual temperature of the water-cooled wall;

[0054] If the rate of change of the highest actual temperature among all the water-cooled walls in the coordinated control system exceeds a preset normal threshold, a function relationship value is obtained according to the rate of change of the highest temperature based on a preset function relationship, and superimposed on the water supply main control command, so as to reduce the sudden rise in water-cooled wall temperature by adding water and prevent water-cooled wall tube rupture. The preset normal threshold indicates that the rate of change of water-cooled wall temperature exceeds the normal range.

[0055] According to some embodiments of the present invention, when the rate of change of the highest temperature among all the actual temperatures of the water-cooled walls in the coordinated control activation of automatic water supply exceeds a preset normal threshold, a function relationship value is obtained according to a preset function relationship based on the rate of change of the highest temperature and superimposed on the water supply main control command, and the following steps are also included:

[0056] The rate of temperature change is determined based on the actual temperature of the water-cooled wall.

[0057] If the rate of temperature change exceeds the preset normal rate of change range, the coordinated control is executed to activate the automatic water supply system. If the rate of change of the highest temperature among all the actual temperatures of the water-cooled walls exceeds the preset normal threshold, the function relationship value is obtained according to the rate of change of the highest temperature based on the preset function relationship, and is superimposed on the water supply main control command.

[0058] According to some embodiments of the present invention, when the rate of change of the highest temperature among all the actual temperatures of the water-cooled walls in the coordinated control activation of automatic water supply exceeds a preset normal threshold, a function relationship value is obtained according to a preset function relationship based on the rate of change of the highest temperature and superimposed on the water supply main control command, and the following steps are also included:

[0059] The quality is judged based on the actual temperature of the water-cooled wall, and the quality judgment result is obtained.

[0060] If the quality judgment result indicates that the actual temperature of the water-cooled wall is good, the coordinated control is executed to put the water supply system into automatic operation. The rate of change of the highest temperature among all the actual temperatures of the water-cooled walls exceeds a preset normal threshold. The function relationship value is obtained according to the rate of change of the highest temperature based on a preset function relationship and is superimposed on the water supply main control command.

[0061] According to a third aspect embodiment of the present invention, a thermal power plant unit includes a coordinated control system for thermal power plant units as described in the first aspect embodiment above. Since the thermal power plant unit adopts all the technical solutions of the coordinated control system for thermal power plant units of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0062] A control device according to a fourth aspect embodiment of the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the coordinated control method for thermal power plant units as described in the second aspect embodiment above. Since the control device employs all the technical solutions of the coordinated control method for thermal power plant units described in the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0063] According to a fifth aspect embodiment of the present invention, a computer-readable storage medium stores computer-executable instructions for performing the coordinated control method for a thermal power plant unit as described in the second aspect embodiment above. Since the computer-readable storage medium employs all the technical solutions of the coordinated control method for a thermal power plant unit of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0064] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0065] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0066] Figure 1 This is a partial system block diagram of a coordinated control system for a thermal power plant unit according to an embodiment of the present invention;

[0067] Figure 2 This is a flowchart of a coordinated control method for a thermal power plant unit according to an embodiment of the present invention.

[0068] Figure label:

[0069] Total fuel command module 110, boiler main control command module 120, conversion module 130, linear module 140, second lag module 150;

[0070] First lag module 210, subtractor module 220, first adder module 230;

[0071] Reference hysteresis module 300;

[0072] High-selection module 400;

[0073] Wind-coal ratio function module 500;

[0074] Variable load air volume feedforward module 610, second adder module 620;

[0075] Third lagging module 700. Detailed Implementation

[0076] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0077] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0078] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0079] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0080] The following will combine Figure 1 and Figure 2 The coordinated control system of a thermal power plant unit according to the first aspect of the present invention will be clearly and completely described. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0081] According to a first aspect of the present invention, a coordinated control system for a thermal power plant unit includes a unit control command module, a load change determination module, a reference lag module 300, a high-speed selection module 400, and a wind-coal ratio function module 500.

[0082] The unit control command module is used to acquire unit control signals, which include initial unit control signals and target unit control signals after changes in unit load.

[0083] The load change determination module has a control signal input terminal and a control signal output terminal. The control signal input terminal is connected to the unit control command module. The load change determination module is used to determine the control signal change amount based on the initial unit control signal and the target unit control signal, and generate a first control signal based on the target unit control signal and the control signal change amount. When the control signal change amount is positive, the first control signal is greater than the target unit control signal; when the control signal change amount is negative, the first control signal is less than the target unit control signal.

[0084] The reference lag module 300 has a lag input terminal and a lag output terminal. The lag input terminal is connected to the unit control command module. The reference lag module 300 is used to output the target unit control signal with a lag time behind the formation time of the boiler coal quantity command.

[0085] The high-selection module 400 has a first input terminal, a second input terminal, and a high-selection output terminal. The first input terminal is connected to the hysteresis output terminal, and the second input terminal is connected to the control signal output terminal. The high-selection module 400 is used to output the larger value between the target unit control signal and the first control signal.

[0086] The air-coal ratio function module 500 has its input terminal connected to the high-selection output terminal. The air-coal ratio function module 500 is used to generate a boiler air volume command based on the larger value between the target unit control signal and the first control signal. The boiler coal volume command is obtained through PID calculation. The time of generating the boiler air volume command based on the first control signal is earlier than the time of forming the boiler coal volume command.

[0087] The unit control command module includes a total fuel command module 110, a boiler main control command module 120, and a conversion module 130. The total fuel command module 110 outputs a total fuel control signal; the boiler main control command module 120 outputs a boiler main control signal; the conversion module 130 has a first selection terminal, a second selection terminal, and a selection output terminal. The first selection terminal is connected to the total fuel command module 110, the second selection terminal is connected to the boiler main control command module 120, and the selection output terminal is connected to both the control signal input terminal and the hysteresis input terminal. The conversion module 130 selects one of the total fuel control signal and the boiler main control signal as the unit control signal and outputs it through the selection output terminal.

[0088] Changes in unit load will cause changes in both the total fuel control signal and the boiler main control signal. Both signals can generate boiler airflow commands, and either can be selected as the base signal for the boiler airflow command. The conversion module 130 is used to select whether to output the total fuel control signal or the boiler main control signal. Specifically, when the conversion module 130 is set to the OFF state, it outputs the boiler main control signal; conversely, when it is set to the ON state, it outputs the total fuel control signal.

[0089] The load change determination module includes a first lag module 210, a subtractor module 220, and a first adder module 230. The first lag module 210 has its input connected to the unit control command module and is used to delay the output of the initial unit control signal. The subtractor module 220 has a first subtraction input, a second subtraction input, and a subtraction output. The first subtraction input is used to input the target unit control signal, and the second subtraction input is connected to the output of the first lag module 210. The first adder module 230 has a first addition input, a second addition input, and a first addition output. The first addition input is used to input the target unit control signal, the second addition input is connected to the subtraction output, and the first addition output is connected to the second addition input.

[0090] When the unit load changes, the conversion module 130 outputs the target unit control signal to the first lag module 210 and the subtractor module 220. At this time, the first lag module 210 outputs the initial unit control signal stored before the unit load change with a lag, and stores the currently input target unit control signal. This lag means that the initial unit control signal stored before the unit load change is delayed until the current moment when the target unit control signal is input after the unit load change, and then outputs it to the subtractor module 220. If the unit load increases, and the initial unit control signal is less than the target unit control signal, the output value of the subtractor module 220 is the target unit control signal minus the initial unit control signal, which is a positive number. Then the output value of the first adder module 230 is the target unit control signal minus the initial unit control signal plus the target unit control signal. That is, the first control signal must be greater than the target unit control signal output by the reference lag module 300. At this time, the high-selection module 400 outputs the first control signal to the air-coal ratio function module 500 to generate the boiler air volume command. The boiler coal quantity command is obtained through PID calculation. The time for generating the boiler air volume command based on the first control signal must precede the time for generating the boiler coal quantity command, thus enabling the addition of air before coal when the unit increases load.

[0091] If the unit load decreases, and the initial unit control signal is greater than the target unit control signal, the output value of the subtractor module 220 is the target unit control signal minus the initial unit control signal, which is a negative number. Then, the output value of the first adder module 230 is the target unit control signal minus the initial unit control signal plus the target unit control signal. That is, the first control signal is less than the target unit control signal output by the reference lag module 300. At this time, the high-selection module 400 outputs the target unit control signal output by the reference lag module 300 to the air-coal ratio function module 500 to generate the boiler air volume command. The reference lag module 300 outputs the target unit control signal after the formation time of the boiler coal volume command, so that the coal is reduced first and then the air volume is reduced when the unit load is reduced.

[0092] Conventional coal-air cross-limiting loops are implemented through coal-air cross-functions. A drawback of this design is that when the unit is under varying load conditions, improper cross-function settings can cause the unit's coal feed setpoints and airflow setpoints to fail to quickly adapt to the changing load requirements during coordinated control and significant load changes, affecting the speed of coordinated load changes. In contrast, the coordinated control system for thermal power plants in this invention allows for increasing airflow before coal flow when increasing load and decreasing coal flow before decreasing airflow when decreasing load. This enables rapid tracking of changing load requirements, achieving faster coordinated load changes and improving the effectiveness of rapid start-up, shutdown, and load increases / decreases.

[0093] It should be noted that the boiler coal quantity command is obtained through PID calculation, which takes longer than the time taken by the unit control command module, load change determination module, high-speed selection module 400, and air-coal ratio function module 500 to generate the boiler air quantity command. The specific time taken by both has been proven by experiments and has a basis in actual evidence. Moreover, the PID calculation process is more complex and takes longer, which is also known to those skilled in the art.

[0094] The process by which the air-coal ratio function module 500 generates boiler air volume instructions based on the first control signal or the target unit control signal will not be described in detail here. The working principle of the air-coal ratio function module 500 is existing technology known to those skilled in the art. The specific function processing can be implemented by selecting existing technology according to the actual situation, and is not limited here.

[0095] In the embodiments of the present invention, the specific modules mentioned above are all common modules in the DCS system of thermal power plant units, and the specific working principles are all existing technologies known to those skilled in the art, and will not be described in detail here.

[0096] According to the coordinated control system of a thermal power plant unit of the present invention, the unit control command module outputs a target unit control signal after the unit load changes. The load change determination module can determine the change in the control signal before and after the unit load change and generate a first control signal. The reference lag module 300 can output the target unit control signal with a lag time after the formation time of the boiler coal quantity command. The high selection module 400 can output the larger value between the target unit control signal and the first control signal. When the change in the control signal is positive, it indicates that the unit load has increased. At this time, the first control signal is greater than the target unit control signal, and the time to generate the boiler air volume command directly based on the first control signal is shorter than the formation time of the boiler coal quantity command obtained through PID calculation. When the change in the control signal is negative, it indicates that the unit load has decreased. At this time, the first control signal is less than the target unit control signal, and the boiler air volume command is generated based on the target unit control signal with a lag time after the formation time of the boiler coal quantity command. This allows for the addition of air volume before coal volume when the unit load increases, and the reduction of coal volume before air volume when the unit load decreases. This enables rapid tracking of the requirements of load change conditions and achieves rapid coordinated load change. The coordinated control system for thermal power plant units in this embodiment of the invention can improve the efficiency of rapid start-up and shutdown and rapid load increase / decrease.

[0097] In some embodiments of the present invention, reference is made to Figure 1The system also includes a variable load airflow feedforward module 610 and a second adder module 620. The variable load airflow feedforward module 610 outputs dynamic additions and subtractions to compensate for the airflow command delay caused by the time difference between the boiler and turbine's actions during variable load conditions. The second adder module 620 has a third adder input, a fourth adder input, and a second adder output. The third adder input is connected to the output of the air-coal ratio function module 500, and the fourth adder input is connected to the variable load airflow feedforward module 610. The second adder module 620 compensates for the boiler airflow command through dynamic additions and subtractions to compensate for the airflow command delay caused by the time difference between the boiler and turbine's actions during variable load conditions. The variable load airflow feedforward module 610 can compensate for the boiler airflow command through dynamic additions and subtractions, overcoming the airflow command delay caused by the time difference between the boiler and turbine's actions during variable load conditions.

[0098] In some embodiments of the present invention, reference is made to Figure 1 A linear module 140 is also included between the boiler main control command module 120 and the conversion module 130. The linear module 140 is used to limit the amplitude of the unit control signal. Limiting the amplitude of the unit control signal can prevent overload of the unit control signal and ensure the signal quality of the unit control signal. The working principle of the linear module 140 is prior art known to those skilled in the art and will not be described in detail here. The specific model of the linear module 140 can be selected according to actual needs and is not limited here.

[0099] In some embodiments of the present invention, reference is made to Figure 1 A second hysteresis module 150 is also included between the total fuel command module 110 and the conversion module 130. The second hysteresis module 150 is used to delay the output of the total fuel control signal, which can make the total fuel control signal smoother and ensure the signal quality of the total fuel control signal.

[0100] In some embodiments of the present invention, reference is made to Figure 1 Between the high-selection module 400 and the air-coal ratio function module 500, there is also a third lag module 700. The third lag module 700 is used to lag the output of the target unit control signal or the first control signal, which can make the target unit control signal or the first control signal smoother and ensure the signal quality of the target unit control signal or the first control signal.

[0101] In some embodiments of the present invention, an economizer feedwater bypass pipeline is installed near the feedwater pipeline. The economizer feedwater bypass pipeline is equipped with an electrically operated shut-off valve, an electrically operated regulating valve, a flow measuring device, a flow transmitter, and a thermocouple. The electrically operated shut-off valve allows the economizer feedwater bypass pipeline to be switched on or off under low load conditions. The electrically operated regulating valve allows the feedwater flow rate to be adjusted under low load conditions. The flow measuring device, flow transmitter, and thermocouple are used to detect the feedwater flow rate and temperature on the economizer feedwater bypass pipeline.

[0102] When the unit operates at low load, to reduce the heat absorbed by the feedwater passing through the economizer, the electric shut-off valve on the main line is closed, while the electric shut-off valve on the economizer feedwater bypass pipeline is open. Simultaneously, the feedwater flow rate is controlled in real-time by the electric regulating valve on the economizer feedwater bypass pipeline. Flow measurement devices, flow transmitters, and thermocouples on the economizer feedwater bypass pipeline can monitor the feedwater flow rate and temperature in real-time. Most of the heat exchange between the feedwater and flue gas occurs through the economizer. When the feedwater does not pass through the economizer, most of the heat from the flue gas is not carried away by the feedwater. Therefore, the temperature of the flue gas at the denitrification inlet does not decrease with the load reduction, thus improving the denitrification effect.

[0103] In some embodiments, since the feedwater does not pass through the economizer, the low feedwater flow rate main fuel trip protection condition and setting value in the economizer inlet pipe are deleted, and the low feedwater flow rate main fuel trip protection in the economizer outlet pipe is added.

[0104] In some embodiments of the present invention, the boiler coal mill includes a dynamic and static coal separator, a coal mill separator lubricating oil pump motor, a coal mill separator motor cooling fan, and a coal mill dynamic and static separator frequency converter. The dynamic and static separator is a controllable centrifugal separator. The coal mill dynamic and static separator motor lubrication system consists of a dry oil pump, motor, oil tank, and pipelines, used to lubricate the bearings in the drive unit. The coal mill separator motor cooling fan is used to cool the coal mill separator lubricating oil pump motor. The coal mill dynamic and static separator drive unit is connected to the frequency converter motor via a belt to realize the rotation of the rotating impeller. The function of the coal mill dynamic and static separator frequency converter is to adjust the rotation speed of the rotating impeller. Throughout the operation, the impeller speed is adjustable, and the fineness of the coal powder has a functional relationship with the rotation speed of the separator blades. The optimal operating speed of the rotating impeller should be determined through performance experiments.

[0105] Raw coal is ground into pulverized coal by grinding rollers and dried by a single hot air cycle before being conveyed to the pulverized coal motorized static separator. Stationary blades, positioned outside the core pulverized coal separation area, evenly distribute the pulverized coal and gas mixture containing particles of different sizes, tangentially guiding it into the core pulverized coal separation area. The separator's rotating impeller, located inside the core pulverized coal separation area, rotates in the same direction as the tangential airflow, providing crucial centrifugal force for the pulverized coal motorized static separator to perform its separation function. The magnitude of this centrifugal force can be controlled by adjusting the frequency of the pulverized coal motorized static separator's inverter. Within the core pulverized coal separation area, pulverized coal particles of different sizes experience varying centrifugal forces due to their different masses (particle sizes). Larger particles move outwards under centrifugal force, impacting the stationary blades and returning to the grinding disc via the return cone under gravity for further grinding. Pulverized coal reaching the required fineness passes through the rotating impeller blades and, through the distributor's outlet pipe, enters the boiler for combustion via the pulverized coal pipeline.

[0106] To meet the requirements of stable combustion technology under low load, a dynamic static coal separator was added. The dynamic static separator produces more uniform and finer pulverized coal than the static separator, which is more conducive to the complete combustion of pulverized coal in the boiler furnace. This improves the boiler's combustion efficiency under low load and reduces NOx emissions. x This reduces CO2 emissions and is beneficial to environmental protection.

[0107] In some embodiments of the present invention, a three-stage extraction steam to heater inlet electric gate valve, a three-stage extraction steam to heater inlet regulating valve, a three-stage extraction steam to heater outlet electric gate valve, and a heater primary air inlet regulating electric gate are added to the primary air temperature equipment, which can increase the primary air temperature under low load and improve the combustion performance.

[0108] The function of the three-stage extraction steam to heater inlet electric gate valve is to control the flow of steam from the three-stage extraction steam to the heater by opening and closing the valve. The function of the three-stage extraction steam to heater inlet regulating valve is to control the amount of steam used from the three-stage extraction steam to the heater by adjusting the valve opening. The function of the three-stage extraction steam to heater outlet electric gate valve is to control the flow of steam returning from the heater to the three-stage extraction steam. The function of the heater primary air inlet regulating electric valve is to determine the amount of primary air from the heater by adjusting the valve size.

[0109] A heater is a device that uses hot steam to achieve heat exchange. When the unit is running at low load, the amount of steam entering the heater can be controlled by the three-stage extraction steam from the unit, through the electric gate valve at the inlet of the heater, and the regulating valve at the inlet of the heater. The amount of primary air can be adjusted by the electric regulating valve at the primary air inlet of the heater. The regulating valve at the inlet of the heater automatically adjusts the primary air temperature under low load.

[0110] In some embodiments of the present invention, a variable frequency vacuum pump is added to the original three vacuum pumps of the unit. The variable frequency vacuum pump corresponds to the original three vacuum pumps, including the main vacuum pump variable frequency, the secondary vacuum pump variable frequency, and the tertiary vacuum pump variable frequency, which enables the low-pressure cylinder to adjust the vacuum set value under low load.

[0111] In some embodiments of the present invention, when the unit experiences high superheat under varying loads, the desuperheating water flow is adjusted to correct the boiler main control feedforward, thereby reducing the boiler main control output while simultaneously opening the desuperheating water, thus maintaining the superheat within a reasonable range. It should be noted that the specific configuration can be set according to actual conditions and is not limited here.

[0112] The coordinated control system for thermal power plant units in this invention improves the effect of deep peak shaving by adding corresponding equipment. It applies all equipment as a whole to the same thermal power plant unit, which provides guidance for the flexible transformation of other thermal power plant units. It improves the denitrification effect under wide load on the boiler side, improves the stable combustion effect under low load on the boiler side, and improves the vacuum conditions under deep peak shaving on the turbine side. The effects of reducing minimum output, rapid start-up and shutdown, and rapid load increase and decrease under deep peak shaving are more obvious.

[0113] The following will combine Figure 1 and Figure 2 The coordinated control method for thermal power plant units according to the second aspect of the present invention will be clearly and completely described. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0114] According to a second aspect of the present invention, a coordinated control method for thermal power plant units is applied to the coordinated control system for thermal power plant units described in the first aspect of the present invention. The coordinated control method for thermal power plant units includes the following steps:

[0115] Acquire the initial unit control signal and the target unit control signal after the unit load changes;

[0116] The change in control signal is determined based on the initial unit control signal and the target unit control signal;

[0117] A first control signal is generated based on the target unit control signal and the change in the control signal. When the change in the control signal is positive, the first control signal is greater than the target unit control signal, and when the change in the control signal is negative, the first control signal is less than the target unit control signal.

[0118] The air volume command generation strategy is executed based on the target unit control signal and the first control signal. The air volume command generation strategy includes a load increase strategy and a load decrease strategy. The load increase strategy includes the following steps: generating a boiler air volume command based on the first control signal, wherein the boiler coal quantity command is obtained through PID calculation, and the time of generating the boiler air volume command based on the first control signal is earlier than the formation time of the boiler coal quantity command. The load decrease strategy includes the following steps: generating a boiler air volume command based on the target unit control signal after the formation time of the boiler coal quantity command, so that when the unit increases the load, air volume is increased before coal is added, and when the unit decreases the load, coal is reduced before air volume is reduced.

[0119] The air volume command generation strategy is executed based on the target unit control signal and the first control signal, including the following steps: if the target unit control signal is less than the first control signal, the load increase strategy is executed; if the target unit control signal is greater than the first control signal, the load decrease strategy is executed.

[0120] When the unit load changes, the conversion module 130 outputs the target unit control signal to the first lag module 210 and the subtractor module 220. At this time, the first lag module 210 outputs the initial unit control signal stored before the unit load change with a lag, and stores the currently input target unit control signal. This lag means that the initial unit control signal stored before the unit load change is delayed until the current moment when the target unit control signal is input after the unit load change, and then outputs it to the subtractor module 220. If the unit load increases, and the initial unit control signal is less than the target unit control signal, the output value of the subtractor module 220 is the target unit control signal minus the initial unit control signal, which is a positive number. Then the output value of the first adder module 230 is the target unit control signal minus the initial unit control signal plus the target unit control signal. That is, the first control signal must be greater than the target unit control signal output by the reference lag module 300. At this time, the high-selection module 400 outputs the first control signal to the air-coal ratio function module 500 to generate the boiler air volume command. The boiler coal quantity command is obtained through PID calculation. The time for generating the boiler air volume command based on the first control signal must precede the time for generating the boiler coal quantity command, thus enabling the addition of air before coal when the unit increases load.

[0121] If the unit load decreases, and the initial unit control signal is greater than the target unit control signal, the output value of the subtractor module 220 is the target unit control signal minus the initial unit control signal, which is a negative number. Then, the output value of the first adder module 230 is the target unit control signal minus the initial unit control signal plus the target unit control signal. That is, the first control signal is less than the target unit control signal output by the reference lag module 300. At this time, the high-selection module 400 outputs the target unit control signal output by the reference lag module 300 to the air-coal ratio function module 500 to generate the boiler air volume command. The reference lag module 300 outputs the target unit control signal after the formation time of the boiler coal volume command, so that the coal is reduced first and then the air volume is reduced when the unit load is reduced.

[0122] Conventional coal-air cross-limiting loops are implemented through coal-air cross-functions. A drawback of this design is that when the unit is under varying load conditions, improper cross-function settings can cause the unit's coal feed setpoints and airflow setpoints to fail to quickly adapt to the changing load requirements during coordinated control and significant load changes, affecting the speed of coordinated load changes. In contrast, the coordinated control system for thermal power plants in this invention allows for increasing airflow before coal flow when increasing load and decreasing coal flow before decreasing airflow when decreasing load. This enables rapid tracking of changing load requirements, achieving faster coordinated load changes and improving the effectiveness of rapid start-up, shutdown, and load increases / decreases.

[0123] According to the coordinated control method for thermal power plant units of this invention, by determining the sign of the change in control signal after a change in unit load, the increase or decrease in unit load can be judged. When the change in control signal is positive, it indicates an increase in unit load. The time to generate the boiler air volume command directly based on the first control signal is shorter than the formation time of the boiler coal volume command obtained through PID calculation. When the change in control signal is negative, it indicates a decrease in unit load. The boiler air volume command is generated based on the time when the target unit control signal lags behind the formation time of the boiler coal volume command. This allows for the prioritization of air volume before coal volume when the unit load increases, and the prioritization of coal volume before air volume when the unit load decreases. This enables rapid tracking of the requirements of load change conditions and achieves rapid coordinated load change. The coordinated control method for thermal power plant units of this invention improves the effectiveness of rapid start-up and shutdown and rapid load increase / decrease.

[0124] In some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0125] In response to the mill start-up configuration signal, the preset mill start-up coal feed rate and preset mill start-up water feed rate are increased. The mill start-up configuration signal is used to characterize the start-up of the coal mill and coal feeder.

[0126] In response to the mill shutdown configuration signal, the preset mill shutdown coal feed rate and preset mill shutdown water feed rate are reduced. The mill shutdown configuration signal is used to indicate that the coal mill or coal feeder has stopped working.

[0127] During deep peak shaving and load adjustment in power plants, the rate of load change is influenced by the opening of the turbine control valve, but also significantly depends on changes in coal and water feed, specifically the changes in coal and water feed rates while maintaining a constant coal-water ratio, especially during the start-up and shutdown of coal mills for deep peak shaving. The simultaneous operation of the coal mill and feeder generates a start-up configuration signal. If either the coal mill or feeder's operating signal is absent, it cannot be considered a start-up. The shutdown configuration signal is the negation of the start-up configuration signal. By pre-increasing or decreasing the amount of coal and water feed when the coal mill and feeder start and stop, the coal feed can be rapidly adjusted, thus achieving rapid load adjustments.

[0128] The timing of coal and water feed can be set via the time constant pulse module. Preset coal and water feed rates for mill start-up can be output to the fuel control module via the adder module. It should be noted that the pulse timing and magnitude for coal and water feed are determined through actual field testing and are not specifically limited here.

[0129] In some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0130] Obtain the actual generator power and the actual main steam pressure of the unit;

[0131] Based on the preset target generator power and the actual generator power of the unit, as well as the preset target main steam pressure and the actual main steam pressure of the unit, a variable load feedforward common command is generated to correct the power deviation between the actual generator power and the target generator power, and the main steam pressure deviation between the actual main steam pressure and the target main steam pressure.

[0132] Variable load feedforward common command is a loop that sends commands to feedwater, fuel, total air volume, primary air pressure, and feedforwards to desuperheating water control valves and coal mill hot air control valves. Its function is to proactively adjust the control commands of feedwater, fuel, total air volume, primary air pressure, desuperheating water control valves, and coal mill hot air control valves after a change in unit commands, simultaneously coordinating actions to rapidly change boiler combustion efficiency and maintain the unit's dynamic energy balance. Conventional variable load feedforward common command configurations typically use the differential component of the load command as a reference quantity. The slope of the unit's target power and the load amplitude are processed through specific logic operations to derive the advance acceleration value for dynamic process regulation, but the accuracy is still not very high. The coordinated control method for thermal power plant units in this invention obtains a high accuracy rate for the variable load feedforward common command by correcting the power deviation between the actual generator power and the target generator power, and correcting the main steam pressure deviation between the actual main steam pressure and the target main steam pressure. This allows for better dynamic acceleration of boiler adaptation to different operating conditions, shortening the boiler output, pressure, and temperature response time, and better coordination with the turbine to achieve rapid load increases and decreases.

[0133] In some embodiments, if the power deviation is less than a preset normal power deviation range and the main steam pressure deviation is less than a preset normal main steam pressure range, then the output of the variable load feedforward common command is zero.

[0134] It should be noted that power deviation and main steam pressure deviation can be corrected using a multiplier module. The specific principle is existing technology known to those skilled in the art and will not be elaborated here. Furthermore, other function modules can also be used to correct power deviation and main steam pressure deviation, and this should not be considered a limitation of the present invention.

[0135] In some embodiments of the present invention, the coordinated control method for thermal power plant units further includes the following steps:

[0136] Obtain the real-time actual temperature of the water-cooled wall;

[0137] If the rate of change of the highest actual temperature among all water-cooled walls in the automatic water supply control exceeds the preset normal threshold, the function relationship value is obtained according to the preset function relationship based on the rate of change of the highest temperature, and superimposed on the water supply main control command, so as to reduce the sudden rise in water-cooled wall temperature by adding water and prevent water-cooled wall tube rupture. The preset normal threshold indicates that the rate of change of water-cooled wall temperature exceeds the normal range.

[0138] During load changes, boiler tube rupture may occur due to excessively high water-cooled wall temperatures. The coordinated control method for thermal power plant units in this invention reduces water-cooled wall temperatures by adding water, thereby improving the safety protection of water-cooled walls in deep peak shaving of coal-fired units and providing guidance for the safety protection of water-cooled walls in other coal-fired units.

[0139] In some embodiments of the present invention, when the rate of change of the highest temperature among the actual temperatures of all water-cooled walls in the coordinated control of automatic water supply exceeds a preset normal threshold, a function relationship value is obtained according to a preset function relationship based on the rate of change of the highest temperature and superimposed on the water supply main control command, and the following steps are also included:

[0140] The rate of temperature change is determined based on the actual temperature of the water-cooled wall.

[0141] If the rate of temperature change exceeds the preset normal rate of change range, the coordinated control is activated and the rate of change of the highest actual temperature among all water-cooled walls in the automatic water supply system exceeds the preset normal threshold. The function relationship value is obtained according to the rate of change of the highest temperature based on the preset function relationship and superimposed on the water supply main control command.

[0142] If the rate of temperature change is outside the preset normal rate of change range, it indicates that the temperature change is abnormal, and the thermal system may experience accidents such as pipe bursts, requiring timely adjustment of the water supply control.

[0143] In some embodiments of the present invention, when the rate of change of the highest temperature among the actual temperatures of all water-cooled walls in the coordinated control of automatic water supply exceeds a preset normal threshold, a function relationship value is obtained according to a preset function relationship based on the rate of change of the highest temperature and superimposed on the water supply main control command, and the following steps are also included:

[0144] The quality is judged based on the actual temperature of the water-cooled wall, and the quality judgment result is obtained.

[0145] If the quality judgment result indicates that the actual temperature of the water-cooled wall is good, the coordinated control is executed to activate the automatic water supply system. The rate of change of the highest actual temperature among all water-cooled walls exceeds the preset normal threshold. Based on the rate of change of the highest temperature, the function relationship value is obtained according to the preset function relationship and superimposed on the water supply main control command.

[0146] If the quality assessment result indicates that the actual temperature of the water-cooled wall is a bad point, it means that the temperature is abnormal and the thermal sensing element has malfunctioned. This point will not be included in the comparison of the highest temperature in the water-cooled wall temperature range. It should be noted that the quality assessment is implemented through a quality assessment module, and the specific working principle is existing technology known to those skilled in the art, and will not be elaborated here.

[0147] In some embodiments, the actual temperatures of all water-cooled walls are determined by temperature change rate judgment and quality judgment, and then the maximum value of the actual water-cooled wall temperature is obtained. During deep peak shaving, when the rate of change of the highest actual water-cooled wall temperature exceeds a preset normal threshold, the value is directly superimposed on the water supply main control command after being limited by a function. This ensures that if the rate of change of water-cooled wall temperature is too high, water is added to lower the water-cooled wall temperature, thereby achieving safety protection against overheating of the water-cooled wall under deep peak shaving.

[0148] The thermal power plant unit according to a third aspect embodiment of the present invention includes the coordination and control system of the thermal power plant unit described in the first aspect embodiment. Since the thermal power plant unit adopts all the technical solutions of the coordination and control system of the thermal power plant unit described in the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0149] Furthermore, a fourth aspect of the present invention provides a control device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor and the memory may be connected via a bus or other means.

[0150] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0151] The non-transient software program and instructions required to implement the coordinated control method of the thermal power plant unit in the above embodiments are stored in the memory. When executed by the processor, the coordinated control method of the thermal power plant unit in the above embodiments is executed.

[0152] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0153] Furthermore, a fifth aspect embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller, for example, by the processor of the aforementioned control device, such that the processor performs the coordinated control method for thermal power plant units described in the above embodiments.

[0154] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0155] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A coordinated control system for a thermal power plant unit, characterized in that, Includes the following steps: The unit control command module is used to acquire unit control signals, which include initial unit control signals and target unit control signals after changes in unit load. The load change determination module has a control signal input terminal and a control signal output terminal. The control signal input terminal is connected to the unit control command module. The load change determination module is used to determine the control signal change amount based on the initial unit control signal and the target unit control signal, and to generate a first control signal based on the target unit control signal and the control signal change amount. When the control signal change amount is positive, the first control signal is greater than the target unit control signal; when the control signal change amount is negative, the first control signal is less than the target unit control signal. The reference lag module has a lag input terminal and a lag output terminal. The lag input terminal is connected to the unit control command module. The reference lag module is used to output the target unit control signal with a lag time after the formation time of the boiler coal quantity command. The high-selection module has a first input terminal, a second input terminal, and a high-selection output terminal. The first input terminal is connected to the hysteresis output terminal, and the second input terminal is connected to the control signal output terminal. The high-selection module is used to output the larger value between the target unit control signal and the first control signal. The air-coal ratio function module has its input end connected to the high-selection output end. The air-coal ratio function module is used to generate a boiler air volume command based on the larger value between the target unit control signal and the first control signal. The boiler coal volume command is obtained through PID calculation, and the time of generating the boiler air volume command based on the first control signal is earlier than the time of forming the boiler coal volume command. The load change determination module includes: The first lag module has its input terminal connected to the unit control command module and is used to lag the output of the initial unit control signal. The subtractor module has a first subtraction input terminal, a second subtraction input terminal, and a subtraction output terminal. The first subtraction input terminal is used to input the target unit control signal, and the second subtraction input terminal is connected to the output terminal of the first hysteresis module. The first adder module has a first adder input terminal, a second adder input terminal, and a first adder output terminal. The first adder input terminal is used to input the target unit control signal. The second adder input terminal is connected to the subtraction output terminal, and the first adder output terminal is connected to the second adder input terminal.

2. The coordinated control system for thermal power plant units according to claim 1, characterized in that, Also includes: The variable load air volume feedforward module is used to output dynamic addition and subtraction, which is used to compensate for the air volume command delay caused by the time difference between the boiler and the turbine during variable load. The second adder module has a third adder input terminal, a fourth adder input terminal, and a second adder output terminal. The third adder input terminal is connected to the output terminal of the air-coal ratio function module, and the fourth adder input terminal is connected to the variable load air volume feedforward module. The second adder module is used to compensate the boiler air volume command through the dynamic addition and subtraction to compensate for the air volume command delay caused by the time difference between the boiler and the turbine during variable load.

3. The coordinated control system for thermal power plant units according to claim 1, characterized in that, The unit control command module includes: The total fuel command module is used to output total fuel control signals; The boiler main control command module is used to output boiler main control signals; The conversion module has a first selection terminal, a second selection terminal, and a selection output terminal. The first selection terminal is connected to the total fuel command module, the second selection terminal is connected to the boiler main control command module, and the selection output terminal is connected to the control signal input terminal and the hysteresis input terminal respectively. The conversion module is used to select one of the total fuel control signal and the boiler main control signal as the unit control signal and output it through the selection output terminal.

4. A coordinated control method for thermal power plant units, characterized in that, The coordinated control system for a thermal power plant unit as described in any one of claims 1 to 3, wherein the coordinated control method for the thermal power plant unit comprises the following steps: Acquire the initial unit control signal and the target unit control signal after the unit load changes; The change in control signal is determined based on the initial unit control signal and the target unit control signal; A first control signal is generated based on the target unit control signal and the change in the control signal. When the change in the control signal is positive, the first control signal is greater than the target unit control signal. When the change in the control signal is negative, the first control signal is less than the target unit control signal. The air volume command generation strategy is executed according to the target unit control signal and the first control signal. The air volume command generation strategy includes a load increase strategy and a load decrease strategy. The load increase strategy includes the following steps: generating a boiler air volume command according to the first control signal, wherein the boiler coal quantity command is obtained through PID calculation, and the time of generating the boiler air volume command according to the first control signal is earlier than the formation time of the boiler coal quantity command. The load decrease strategy includes the following steps: generating a boiler air volume command according to the target unit control signal after the formation time of the boiler coal quantity command, so that when the unit increases the load, air volume is increased first and then coal is added, and when the unit decreases the load, coal is reduced first and then air volume is reduced.

5. The coordinated control method for thermal power plant units according to claim 4, characterized in that, The step of executing the air volume command generation strategy based on the target unit control signal and the first control signal includes the following steps: If the target unit control signal is less than the first control signal, the load increase strategy is executed. If the target unit control signal is greater than the first control signal, the load reduction strategy is executed.

6. The coordinated control method for thermal power plant units according to claim 4, characterized in that, The coordinated control method for thermal power plant units also includes the following steps: In response to the mill start-up configuration signal, the preset mill start-up coal feed rate and preset mill start-up water feed rate are increased. The mill start-up configuration signal is used to characterize the start-up of the coal mill and the coal feeder. In response to the mill shutdown configuration signal, the preset mill shutdown coal feed rate and preset mill shutdown water feed rate are reduced. The mill shutdown configuration signal is used to indicate that the coal mill or coal feeder has stopped working.

7. The coordinated control method for thermal power plant units according to claim 4, characterized in that, The coordinated control method for thermal power plant units also includes the following steps: Obtain the actual generator power of the unit; A variable load feedforward common command is generated based on the preset target generator power and the actual generator power of the unit to correct the power deviation between the actual generator power and the target generator power.

8. A thermal power plant unit, characterized in that, Includes the coordinated control system for thermal power plant units as described in any one of claims 1 to 3.

9. A computer-readable storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions are used to execute the coordinated control method for thermal power plant units as described in any one of claims 4 to 7.

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