A control method for improving the operating flexibility of coal-fired units by coordinating main and auxiliary power generation

Abstract

The present invention discloses a control method for improving the operational flexibility of coal-fired units by coordinating the main and auxiliary systems. The method optimizes the fuel instruction control loop of the pulverizing system, adds a variable load correction signal, couples it with the fuel quantity instruction of the pulverizing system in a feedforward manner, and utilizes heat storage utilization methods such as condensate throttling and high-pressure steam extraction throttling to decompose the unit load instruction at the initial stage of load variation. The power variation is borne by three parts: the coordinated control system, the condensate throttling subsystem, and the high-pressure steam extraction throttling subsystem, thereby improving the power control effect during the load variation process. By optimizing the main and auxiliary load instruction control strategy and making full use of the heat storage on the turbine side, the limitation of the large delay characteristic of the pulverizing system on the load variation rate of the unit is broken through, and the power deviation of the unit during the load variation process is effectively reduced. At the same time, the probability of the occurrence of phenomena such as overheating of the heating surface due to over-adjustment of the coal quantity during the rapid load variation process is reduced, thereby comprehensively improving the operational flexibility and safety of the coal-fired unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal-fired thermal control, and in particular relates to a control method for improving the operational flexibility of a coal-fired unit by coordinated matching of main and auxiliary units. Background Art

[0002] With the rapid development of new power systems, the grid's demand for flexibility from coal-fired units is increasing. However, the high latency and inertia of coal-fired unit pulverizing systems limit further increases in load-scaling rates during peak load regulation. Boiler load is primarily regulated by the amount of coal fed to the boiler. However, load-scaling commands for coal-fired units are generated by the load management and control center, transmitted to the boiler main controller, and then to the boiler control system at the basic control level before being passed to the pulverizing system. The conversion of raw coal into boiler input heat through grinding, transportation, and combustion takes a long time, resulting in a discrepancy between the unit's real-time power generation and the load command during load-scaling. Improving control strategies by considering the coordination of main and auxiliary equipment can enhance the operational flexibility of coal-fired power generation units. Boiler systems and regenerative heat recovery systems contain a large amount of available energy storage. During load-scaling, throttling of high-pressure heater extraction steam and condensate flow can improve the stability of the unit's output power. Furthermore, utilizing the unit's thermal energy output to generate work reduces the burden of coal-feed control, reduces the risk of heating surface overheating caused by overfeeding, and enhances unit operational safety. Therefore, during the load change process of the unit, the internal heat storage of the coal-fired unit is converted into work capacity, realizing the comprehensive utilization of multiple heat storages, effectively reducing the power deviation during the load change process, and thus improving the operating flexibility and safety of the unit. Summary of the Invention

[0003] To address the problem of boiler system fuel quantity changes failing to match load command changes during unit load changes due to the significant delay of the pulverizing system, this invention provides a control method for enhancing the operational flexibility of coal-fired units by coordinating the main and auxiliary engines. This method, based on the coordinated matching of the main and auxiliary engines, fully utilizes the unit's thermal storage to reduce power deviations during load changes, thereby comprehensively improving the unit's operational flexibility and safety.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A control method for improving the operational flexibility of a coal-fired unit by coordinated matching of main and auxiliary components. After receiving a load increase instruction from a load management control center, the coal-fired unit calculates the heat required for heating the steam-water side of the boiler system under the current load instruction of the coal-fired unit, divides the heat required by the heat input to the boiler system into a quotient, and uses the calculated heat as a variable load coal quantity correction signal. The calculated heat is then superimposed on the pulverizing system fuel instruction in a feedforward manner. At the same time, it is determined whether the value of the variable load coal quantity correction signal is 1. When the value is not 1 at the initial stage of variable load, two energy storage utilization modes are put into use, and decomposition is performed according to a load instruction decomposition model. The decomposition method is as follows: the condensate throttling power limit, the maximum condensate throttling duration, and the change in the high-pressure heater extraction throttling amount are calculated respectively. Within the maximum condensate throttling duration, the load instruction is decomposed into three items corresponding to the coordinated control system, the condensate throttling control subsystem, and the high-pressure heater extraction throttling control subsystem respectively. When the value of the variable load coal quantity correction signal is 1, the load instruction decomposition is terminated to restore the energy storage.

[0006] The calculation method of the variable load coal quantity correction signal is as follows:

[0007]

[0008] Among them, C b Q is the variable load coal quantity correction signal; w is the heat required for heating the steam-water side of the boiler system under the current load instruction, in kJ; B is the fuel quantity at the current moment, in kg / s; q L The lower calorific value of the coal used, in kJ / kg;

[0009] The heat required for heating the steam and water sides of the boiler system under the current load instruction is obtained through the heat balance diagram; in the initial stage of variable load operation, due to the large delay characteristics of the pulverizing system, the heat input to the boiler system is less than the heat required for heating the steam and water sides, so at this time the variable load coal quantity correction signal value is greater than 1. As the load variable process proceeds, the heat input to the boiler system gradually approaches and becomes equal to the heat required for steam and water heating.

[0010] The load instruction decomposition method is as follows: the change of the original load instruction over time is:

[0011]

[0012] Wherein, N is the real-time load, in MW; N0 is the initial load, in MW; v0 is the original load change rate, in MW / min; t is the unit load change operation time, in seconds;

[0013] When the load instruction is decomposed, the calculation method of the variable load instruction undertaken by the coordinated control system is:

[0014]

[0015] Among them, N ccs It is the variable load instruction undertaken by the coordinated control system after the load instruction is decomposed, and the unit is MW; R ccs The load rate limit value of the coordinated control system, in MW / min;

[0016] The calculation method of the load instruction borne by the condensate throttling control subsystem is:

[0017]

[0018] Among them, N ct It is the variable load instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed, in MW; R ct Condensate throttling load rate limit value, unit is MW / min; t max The maximum duration of condensate throttling, in seconds;

[0019] At the same time, it is necessary to limit the load instruction borne by the condensate throttling control subsystem. The limiting method is:

[0020]

[0021] Among them, N ct,m The power limit value of the condensate throttling control subsystem, in MW;

[0022] The calculation method for the load instruction borne by the HV heater extraction throttling control subsystem is:

[0023] N he =NN ccs -N ct

[0024] Among them, N he It is the variable load instruction undertaken by the high-pressure heater extraction throttling control subsystem after the load instruction is decomposed, in MW;

[0025] At the beginning of load variation, a load variation coal quantity correction signal is generated and added to the pulverizing system fuel instruction in a feedforward manner to accelerate the boiler system input energy to follow the load instruction change; at the same time, the coordinated control system load variation rate limit value is input to obtain the load variation instruction undertaken by the coordinated control system after the load instruction is decomposed; the condensate throttling load variation rate limit value is input, and after the duration limit of the condensate throttling control subsystem and the load instruction power limit are applied, the load variation instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed is obtained, the condensate throttling sub-control system is put into operation, the corresponding condensate throttling amount is calculated, and the condensate flow is changed by changing the water gate opening of the deaerator, thereby realizing power variation; the deviation between the target load instruction and the current load is calculated, and the deviation value is input into the PID controller to control the high-pressure heater extraction pipe valve, and the power is controlled by changing the valve opening;

[0026] As the load variation process progresses, the pulverizing system responds so that the heat input to the boiler system gradually matches the heat required for heating the steam and water side. When the two are equal, the coal quantity correction signal value is 1, and the condensate throttling control subsystem and the high-pressure heater extraction throttling control subsystem are decommissioned, allowing the energy storage to recover.

[0027] After the load instruction is decomposed, the relationship between the variable load instruction and the condensate throttling amount undertaken by the condensate throttling control subsystem is:

[0028] N ct =k ct ·Δm ct

[0029] Among them, k ct is the condensate throttling power gain, which has nothing to do with the condensate flow rate but is closely related to the current operating conditions. It is a function directly related to the load and is obtained by fitting the condensate throttling operation data of the unit; Δm ct is the condensate saving flow, unit is kg / s;

[0030] The calculation method for the power limit value of the condensate throttling control subsystem is as follows:

[0031] N ct,m =k ct ·Δm ct,m

[0032] To ensure safe operation, during the load increase process, the limit value of the condensate flow rate Δm ct,m 110% of the minimum protection flow of the condensate pump;

[0033] The calculation method of the maximum duration of condensate throttling is:

[0034]

[0035] Where ρ is the saturated water density in the deaerator, in kg / m 3 ; h0 is the initial water level of the deaerator, in m; h t is the deaerator water level at the end of throttling, in m; V is the available saturated water volume at the corresponding water level in the deaerator, in m 3 ;

[0036] The calculation method for the available saturated water volume at the corresponding water level in the deaerator is:

[0037]

[0038] Wherein, L is the total length of the deaerator, in m; r is the inner diameter of the deaerator, in m; h is the water level, in m.

[0039] The control method of the high-pressure heater extraction steam throttling flow is as follows:

[0040] The deviation between the target load command and the current load is calculated, and the deviation value is input into the PID controller. The set value of the PID controller is set to 0, and the output acts on the extraction pipe valve of the high-pressure heater, and the valve opening is preset to 75%; when the load command is decomposed and input into the coordinated control system and the condensate throttling subsystem, the remaining load command part is borne by the high-pressure heater extraction throttling subsystem. When the deviation between the target load command and the current load occurs, it acts on the PID controller and controls the high-pressure heater extraction pipe throttling valve. The change in valve opening causes the high-pressure heater extraction throttling amount to change, and the turbine work also changes to follow the load command change.

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] 1. Optimize the fuel quantity command control loop of the pulverizing system. Due to the introduction of the variable load coal quantity correction signal, the response speed of the boiler inlet coal quantity is accelerated, and the response time of the coal quantity in the variable load process is reduced.

[0043] 2. By comprehensively using multiple heat storage and utilization methods and throttling the high-pressure steam extraction and condensate water at the initial stage of load change, the power deviation of the unit during load change is effectively reduced, breaking through the problem of limited load regulation rate caused by the long response time of the pulverizing system during load change.

[0044] 3. By orderly utilizing the internal energy storage of coal-fired units, the power control effect during variable load is improved while reducing the burden of coal feed control, reducing the probability of phenomena such as overheating of the heating surface due to over-adjustment of coal flow, and comprehensively improving the operational flexibility and safety of the units. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1Schematic diagram of the control method for improving the operating flexibility of coal-fired units by coordinating the main and auxiliary power units according to the present invention.

[0046] Figure 2 Schematic diagram of the overall configuration of the control method of the present invention

[0047] Figure 3 This is a schematic diagram of load instruction decomposition during the load ramp-up process of a 660MW unit. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] like Figure 1 As shown, the present invention provides a control method for improving the operational flexibility of a coal-fired unit by coordinating the main and auxiliary parts. After the coal-fired unit receives a load increase instruction from a load management control center, it calculates the heat required for heating the steam-water side of the boiler system under the current load instruction of the coal-fired unit, and divides the heat by the heat input into the boiler system as a variable load coal quantity correction signal and superimposes the signal with the fuel instruction of the pulverizing system in a feedforward manner; at the same time, it is judged whether the value of the variable load coal quantity correction signal is 1. When the value is not 1 at the initial stage of variable load, two energy storage utilization modes are put into use, and decomposition is performed according to a load instruction decomposition model. The decomposition method is as follows: the condensate throttling power limit and the maximum duration of condensate throttling and the change of the high-pressure steam extraction throttling amount are calculated respectively. Within the maximum duration of condensate throttling, the load instruction is decomposed into three items corresponding to the coordinated control system, the condensate throttling control subsystem and the high-pressure steam extraction throttling control subsystem respectively. When the value of the variable load coal quantity correction signal is 1, the load instruction decomposition is terminated to restore the energy storage.

[0050] The calculation method of the variable load coal quantity correction signal is as follows:

[0051]

[0052] Among them, C b Q is the variable load coal quantity correction signal; w is the heat required for heating the steam-water side of the boiler system under the current load instruction, in kJ; B is the fuel quantity at the current moment, in kg / s; q L The lower calorific value of the coal used, in kJ / kg;

[0053] The heat required for heating the steam and water sides of the boiler system under the current load instruction is obtained through the heat balance diagram; in the initial stage of variable load operation, due to the large delay characteristics of the pulverizing system, the heat input to the boiler system is less than the heat required for heating the steam and water sides, so at this time the variable load coal quantity correction signal value is greater than 1. As the load variable process proceeds, the heat input to the boiler system gradually approaches and becomes equal to the heat required for steam and water heating.

[0054] The load instruction decomposition method is as follows: the change of the original load instruction over time is:

[0055]

[0056] Wherein, N is the real-time load, in MW; N0 is the initial load, in MW; v0 is the original load change rate, in MW / min; t is the unit load change operation time, in seconds;

[0057] When the load instruction is decomposed, the calculation method of the variable load instruction undertaken by the coordinated control system is:

[0058]

[0059] Among them, N ccs It is the variable load instruction undertaken by the coordinated control system after the load instruction is decomposed, and the unit is MW; R ccs The load rate limit value of the coordinated control system, in MW / min;

[0060] The calculation method of the load instruction borne by the condensate throttling control subsystem is:

[0061]

[0062] Among them, N ct It is the variable load instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed, in MW; R ct Condensate throttling load rate limit value, unit is MW / min; t max The maximum duration of condensate throttling, in seconds;

[0063] At the same time, it is necessary to limit the load instruction borne by the condensate throttling control subsystem. The limiting method is:

[0064]

[0065] Among them, N ct,m The power limit value of the condensate throttling control subsystem, in MW;

[0066] The calculation method for the load instruction borne by the HV heater extraction throttling control subsystem is:

[0067] N he =NN ccs -N ct

[0068] Among them, N he It is the variable load instruction undertaken by the high-pressure heater extraction throttling control subsystem after the load instruction is decomposed, in MW;

[0069] At the beginning of load variation, a load variation coal quantity correction signal is generated and added to the pulverizing system fuel instruction in a feedforward manner to accelerate the boiler system input energy to follow the load instruction change; at the same time, the coordinated control system load variation rate limit value is input to obtain the load variation instruction undertaken by the coordinated control system after the load instruction is decomposed; the condensate throttling load variation rate limit value is input, and after the duration limit of the condensate throttling control subsystem and the load instruction power limit are applied, the load variation instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed is obtained, the condensate throttling control subsystem is put into operation, the corresponding condensate throttling amount is calculated, and the condensate flow is changed by changing the opening of the deaerator upper water gate, thereby realizing power variation; the deviation between the target load instruction and the current load is calculated, and the deviation value is input into the PID controller to control the high-pressure heater extraction pipe valve, and the power is controlled by changing the valve opening;

[0070] As the load variation process progresses, the pulverizing system responds so that the heat input to the boiler system gradually matches the heat required for heating the steam and water side. When the two are equal, the coal quantity correction signal value is 1, and the condensate throttling control subsystem and the high-pressure heater extraction throttling control subsystem are decommissioned, allowing the energy storage to recover.

[0071] After the load instruction is decomposed, the relationship between the variable load instruction and the condensate throttling amount undertaken by the condensate throttling control subsystem is:

[0072] N ct =k ct ·Δm ct

[0073] Among them, k ct is the condensate throttling power gain, which has nothing to do with the condensate flow rate but is closely related to the current operating conditions. It is a function directly related to the load and is obtained by fitting the condensate throttling operation data of the unit; Δm ct is the condensate saving flow, unit is kg / s;

[0074] The calculation method of the condensate throttling power control subsystem limit value is as follows:

[0075] N ct,m =k ct ·Δm ct,m

[0076] To ensure safe operation, during the load increase process, the limit value of the condensate flow rate Δm ct,m 110% of the minimum protection flow of the condensate pump;

[0077] The calculation method of the maximum duration of condensate throttling is:

[0078]

[0079] Where ρ is the saturated water density in the deaerator, in kg / m 3 ; h0 is the initial water level of the deaerator, in m; h t is the deaerator water level at the end of throttling, in m; V is the available saturated water volume at the corresponding water level in the deaerator, in m 3 ;

[0080] The calculation method for the available saturated water volume at the corresponding water level in the deaerator is:

[0081]

[0082] Wherein, L is the total length of the deaerator, in m; r is the inner diameter of the deaerator, in m; h is the water level, in m.

[0083] The control method of the high-pressure heater extraction steam throttling flow is as follows:

[0084] The deviation between the target load command and the current load is calculated, and the deviation value is input into the PID controller. The set value of the PID controller is set to 0, and the output acts on the extraction pipe valve of the high-pressure heater, and the valve opening is preset to 75%; when the load command is decomposed and input into the coordinated control system and the condensate throttling subsystem, the remaining load command part is borne by the high-pressure heater extraction throttling subsystem. When the deviation between the target load command and the current load occurs, it acts on the PID controller and controls the high-pressure heater extraction pipe throttling valve. The change in valve opening causes the high-pressure heater extraction throttling amount to change, and the turbine work also changes to follow the load command change.

[0085] The present invention takes the coordination of main and auxiliary machines into consideration and improves the control strategy. It optimizes the fuel quantity instruction control loop of the pulverizing system and reduces the burden of coal feed quantity control by utilizing heat storage of the unit such as high-pressure steam extraction throttling and condensate throttling. Its overall configuration is as follows: Figure 2 shown. Figure 3 The load command decomposition results for a 660MW unit during the load ramp-up process are presented. Taking a unidirectional step change in the unit's AGC command as an example, during the unit's load ramping process, the load ramp rate limit assumed by the coordinated control system remains unchanged. However, due to the introduction of a load ramp coal quantity correction signal, the coordinated control system's actual power response time is shortened. In the initial load ramping phase, sequential implementation of heat storage utilization methods such as high-pressure heater extraction throttling and condensate throttling significantly increases the load ramp rate. As the load ramping process progresses, the pulverizing system responds, gradually matching the boiler system input energy with the energy required for heating the steam and water sides. When the two are equal, the coal quantity correction signal is set to 1, and the condensate throttling subsystem and the high-pressure heater extraction throttling subsystem are decommissioned, allowing energy storage to recover. It can be seen that during the load ramping process, the unit's response speed becomes faster and power deviation is reduced, which helps improve the unit's operational flexibility and safety.

Claims

1. A control method for improving the operational flexibility of a coal-fired unit by coordinating the main and auxiliary power units, characterized by: After receiving the load increase instruction from the load management control center, the coal-fired unit calculates the heat required for heating the steam-water side of the boiler system under the current load instruction of the coal-fired unit, divides it by the heat input to the boiler system, and uses it as the variable load coal quantity correction signal. The signal is then superimposed on the pulverizing system fuel instruction in a feedforward manner. At the same time, it is determined whether the value of the variable load coal quantity correction signal is 1. When its value is not 1 at the initial stage of variable load, two energy storage utilization modes are put into use. The decomposition is performed according to the load instruction decomposition model. The decomposition method is as follows: the condensate throttling power limit and the maximum duration of condensate throttling and the change of the high-pressure heater extraction throttling amount are calculated respectively. Within the maximum duration of condensate throttling, the load instruction is decomposed into three items corresponding to the coordinated control system, the condensate throttling control subsystem and the high-pressure heater extraction throttling control subsystem respectively. When the value of the variable load coal quantity correction signal is 1, the load instruction decomposition is terminated to restore the energy storage. The calculation method of the variable load coal quantity correction signal is as follows: Among them, C b Q is the variable load coal quantity correction signal; w is the heat required for heating the steam-water side of the boiler system under the current load instruction, in kJ; B is the fuel quantity at the current moment, in kg / s; q L The lower calorific value of the coal used, in kJ / kg; The heat required for heating the steam and water sides of the boiler system under the current load instruction is obtained through the heat balance diagram; in the initial stage of variable load operation, due to the large delay characteristics of the pulverizing system, the heat input to the boiler system is less than the heat required for heating the steam and water sides, so at this time the variable load coal quantity correction signal value is greater than 1. As the load variable process proceeds, the heat input to the boiler system gradually approaches and becomes equal to the heat required for steam and water heating.

2. A control method for improving the operational flexibility of a coal-fired unit by coordinated matching of main and auxiliary power generation according to claim 1, characterized in that: The load instruction decomposition model is decomposed in the following way: the change of the original load instruction over time is: Wherein, N is the real-time load, in MW; N0 is the initial load, in MW; v0 is the original load change rate, in MW / min; t is the unit load change operation time, in seconds; When the load instruction is decomposed, the calculation method of the variable load instruction undertaken by the coordinated control system is: Among them, N ccs It is the variable load instruction undertaken by the coordinated control system after the load instruction is decomposed, and the unit is MW; R ccs The load rate limit value of the coordinated control system, in MW / min; The calculation method of the load instruction borne by the condensate throttling control subsystem is: Among them, N ct It is the variable load instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed, in MW; R ct Condensate throttling load rate limit value, unit is MW / min; t max The maximum duration of condensate throttling, in seconds; At the same time, it is necessary to limit the load instruction borne by the condensate throttling control subsystem. The limiting method is: Among them, N ct,m The power limit value of the condensate throttling control subsystem, in MW; The calculation method for the load instruction borne by the HV heater extraction throttling control subsystem is: N he =N-N ccs -N ct Among them, N he It is the variable load instruction undertaken by the high-pressure heater extraction throttling control subsystem after the load instruction is decomposed, in MW; At the beginning of load variation, a load variation coal quantity correction signal is generated and added to the pulverizing system fuel instruction in a feedforward manner to accelerate the boiler system input energy to follow the load instruction change; at the same time, the coordinated control system load variation rate limit value is input to obtain the load variation instruction undertaken by the coordinated control system after the load instruction is decomposed; the condensate throttling load variation rate limit value is input, and after the duration limit of the condensate throttling control subsystem and the load instruction power limit are applied, the load variation instruction undertaken by the condensate throttling control subsystem after the load instruction is decomposed is obtained, the condensate throttling control subsystem is put into operation, the corresponding condensate throttling amount is calculated, and the condensate flow is changed by changing the opening of the deaerator upper water gate, thereby realizing power variation; the deviation between the target load instruction and the current load is calculated, and the deviation value is input into the PID controller to control the high-pressure heater extraction pipe valve, and the power is controlled by changing the valve opening; As the load variation process progresses, the pulverizing system responds so that the heat input to the boiler system gradually matches the heat required for heating the steam and water side. When the two are equal, the coal quantity correction signal value is 1, and the condensate throttling control subsystem and the high-pressure heater extraction throttling control subsystem are decommissioned, allowing the energy storage to recover.

3. A control method for improving the operational flexibility of a coal-fired unit by coordinated matching of main and auxiliary power generation according to claim 2, characterized in that: After the load instruction is decomposed, the relationship between the variable load instruction and the condensate throttling amount undertaken by the condensate throttling control subsystem is: N ct =k ct ·Δm ct Among them, k ct is the condensate throttling power gain, which has nothing to do with the condensate flow rate but is closely related to the current operating conditions. It is a function directly related to the load and is obtained by fitting the condensate throttling operation data of the unit; Δm ct is the condensate saving flow, unit is kg / s; The calculation method for the power limit value of the condensate throttling control subsystem is as follows: N ct,m =k ct ·Δm ct,m To ensure safe operation, during the load increase process, the limit value of the condensate flow rate Δm ct,m 110% of the minimum protection flow of the condensate pump; The calculation method of the maximum duration of condensate throttling is: Where ρ is the saturated water density in the deaerator, in kg / m 3 ; h0 is the initial water level of the deaerator, in m; h t is the deaerator water level at the end of throttling, in m; V is the available saturated water volume at the corresponding water level in the deaerator, in m 3 ; The calculation method for the available saturated water volume at the corresponding water level in the deaerator is: Wherein, L is the total length of the deaerator, in m; r is the inner diameter of the deaerator, in m; h is the water level, in m.

4. The control method for improving the operational flexibility of a coal-fired unit by coordinated matching of main and auxiliary power generation according to claim 2 is characterized in that: The control method of the high-pressure heater extraction steam throttling flow is as follows: The deviation between the target load command and the current load is calculated, and the deviation value is input into the PID controller. The set value of the PID controller is set to 0, and the output acts on the extraction pipe valve of the high-pressure heater, and the valve opening is preset to 75%; when the load command is decomposed and input into the coordinated control system and the condensate throttling subsystem, the remaining load command part is borne by the high-pressure heater extraction throttling subsystem. When the deviation between the target load command and the current load occurs, it acts on the PID controller and controls the high-pressure heater extraction pipe throttling valve. The change in valve opening causes the high-pressure heater extraction throttling amount to change, and the turbine work also changes to follow the load command change.

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