Instruction self-balancing control system and control method for master-slave feed pump of thermal power generating unit

Abstract

The invention relates to an instruction self-balancing control system and control method for master-slave feed pumps of a thermal power generating unit. The instruction self-balancing control system comprises a PID (Proportion Integration Differentiation) module, an instruction self-balancing calculation module, respective control modules of the feed pumps, corresponding bias modules and addition modules, an average output instruction of all actuators is calculated through a PID module; receiving the average output instruction through an instruction self-balancing calculation module, and dynamically calculating a reference output instruction of the automatic state actuator in combination with the state of the actuator, a manual instruction and an automatic offset value; setting corresponding to each actuator through a bias module, and tracking or setting a bias value according to the state of the actuator; superposing the reference output instruction and the offset value through an addition module to serve as a final control instruction of the automatic state actuator; multi-pump output rebalance after offset adjustment in an automatic mode or output change in a manual state is achieved, and the problems of hysteresis and system disturbance caused by traditional PID adjustment triggered through water supply amount deviation are solved.

Description

Technical Field

[0001] The invention relates to a master-slave type water supply pump instruction self-balancing control system and a control method for a thermal power unit. Background Art

[0002] Current thermal power unit feedwater control systems lack a universal design method for a self-balancing function that allows the output of feedwater pumps in other automatic modes to change without undergoing closed-loop PID calculations to maintain a constant total feedwater pump output when the offset value of any feedwater pump command changes in automatic control mode, or when the output value of a feedwater pump in manual control mode changes. Some control systems can implement this function through integrated modules developed independently by the manufacturer, but this functionality cannot be ported between different control systems. Units lacking this command self-balancing function must use a PID controller to calculate the feedwater flow deviation and output the feedwater flow deviation when a feedwater pump output change in the automatic mode causes a change in feedwater flow, thereby adjusting the feedwater pump commands in other automatic modes to achieve a balanced state in which the total feedwater pump output (i.e., the feedwater flow) remains constant. Compared with the adjustment process that can achieve command self-balancing (change in bias of water supply pump in single automatic mode → change in output instruction of water supply pump → change in water supply quantity → PID calculation of water supply flow → change in water supply pump instruction in automatic mode → change in water supply quantity, PID closed loop adjustment until the water supply quantity is consistent with the set water supply quantity), this adjustment process (change in bias of water supply pump in single automatic mode → change in output of instruction self-balancing calculation module → change in water supply pump instruction in automatic mode) has two defects: (1) the change in water supply quantity caused by the change in water supply pump output, which triggers the PID to calculate and output the water supply quantity deviation, brings unnecessary disturbance to the water supply system and increases the risk of water supply fluctuation; (2) the process links of water supply pump instruction adjustment are significantly increased, the adjustment time of water supply pump is increased, and the timeliness and stability are significantly reduced. In response to this deficiency, the present invention will realize the above-mentioned instruction self-balancing function design based on the functional modules currently available in widely used control systems. Summary of the Invention

[0003] In view of the above situation, in order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a master-slave water supply pump command self-balancing control system and control method for a thermal power unit, which realizes bias adjustment in automatic mode or multi-pump output rebalancing after output change in manual mode through a command self-balancing module (non-PID closed loop), eliminating the hysteresis and system disturbance problems of traditional PID adjustment triggered by water supply deviation.

[0004] The technical solution provided by the present invention is: A master-slave type feedwater pump command self-balancing control system for a thermal power unit is used for the coordinated control of multiple feedwater pumps in a thermal power plant. The control system comprises a PID module, a command self-balancing calculation module, a control module for each feedwater pump, and a bias module and an addition module corresponding to each control module of each feedwater pump. The signal output end of the PID module is connected to the input end of the command self-balancing calculation module, and the output end of the command self-balancing calculation module is connected to the control module of each feedwater pump in turn through the bias module and the addition module corresponding to each feedwater pump control module. PID module: used to calculate the average output command of all water pumps; Instruction self-balancing calculation module: Receives the average instruction output by the PID module, and calculates the self-balancing instruction based on the manual / automatic operation status of each water supply pump, the output instruction of the water supply pump in manual mode, and the bias value of the water supply pump in automatic mode, and dynamically outputs the benchmark output instruction of a single water supply pump in the automatic state; The bias module corresponding to each feed water pump control module: set up for each feed water pump, used to track or set the bias value according to the feed water pump status; The adding module corresponding to each water supply pump control module is used to superimpose the reference output instruction and the offset value as the final control instruction for the automatic state of the water supply pump; Each water supply pump has its own control module: in manual mode, its output instruction is determined by the input parameters received and generated by the interactive interface of the module; in automatic mode, it receives and outputs the output value of the addition module, that is, the sum of the single reference instruction and the bias value, and sends it to the water supply pump regulator terminal for execution.

[0005] A master-slave type water supply pump command self-balancing control method for multi-actuator coordinated control includes the following steps: S1. Calculate the average output command of all actuators through the PID module; S2 receives the average output command by the self-balancing calculation module, combined with the actuator state (manual / automatic), manual command and automatic bias value, dynamically calculates the automatic state actuator base output command; S3. Use the bias module to set each actuator, tracking or setting the bias value based on the actuator status; S4 by adding the module to the reference output command and the bias value superimposed as the final control command of the automatic state actuator; Among them, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the instruction self-balancing module recalculates the reference output instruction in real time, so that other automatic state actuators are adjusted synchronously to keep the total output unchanged.

[0006] Preferably, the reference output instruction of the command self-balancing module is calculated in the following manner: when a water supply pump is in automatic state, the reference output instruction = [PID output × total number of water supply pumps - Σ (bias value of water supply pump in automatic state) - Σ (output value of water supply pump in manual state)] / number of water supply pumps in automatic state.

[0007] All water supply pumps are in manual mode, and the base output command = PID output.

[0008] Preferably, in step S4, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the instruction self-balancing calculation module recalculates the benchmark output instruction, so that the final control instructions of other automatic state actuators are adjusted synchronously to keep the total output unchanged without the need for PID closed-loop adjustment.

[0009] Preferably, the actuator is a feed water pump of a thermal power unit, and the system or method is used for coordinated control of multiple feed water pumps of a thermal power unit.

[0010] In the water supply control system of a thermal power unit, there are two or more water supply pumps that jointly regulate the water supply flow. According to the operation mode of the water supply pump, the water supply control can be divided into three modes: First, all water supply pumps operate in automatic mode, and the water supply regulation PID (hereinafter referred to as the upper PID) will perform autonomous calculations based on the deviation between the actual water supply and the set water supply; the output instruction of a single water supply pump is the sum of the output of the upper PID plus the output of the instruction bias module of this pump. The instruction output by the instruction bias module is determined by the input parameters received and generated by the interactive interface of the module. The increase or decrease of the output instruction of this pump will affect the output of other pumps, and ultimately achieve a result where the upper PID regulation instruction remains unchanged. The purpose is to keep the sum of the pump outputs unchanged; secondly, all water supply pumps are running in manual mode, the upper PID exits autonomous operation, and tracks the average value of all water supply pump instructions; the output instruction of each water supply pump is determined by the input parameters received and generated by the interactive interface of each pump control module, and the output of the instruction bias module of each water supply pump tracks the difference between the output instruction of this pump and the upper PID instruction; thirdly, some water supply pumps are in automatic mode and other pumps are in manual mode. Under this working condition, the working mode of the upper PID, the working mode of a single water supply pump in automatic mode and the working mode of the bias module are the same as those in mode one; the working mode of a single water supply pump in manual mode and the working mode of the bias module are the same as those in mode two. The present invention has the anti-interference self-balancing ability of the water supply system when the water supply pump output bias is adjusted in the automatic state or the output changes in the manual state, and can reach a new water supply pump output balance state without the closed-loop control of the water supply PID, thereby reducing the risk of water supply fluctuations and the degree of dependence on the quality of PID closed-loop regulation; reducing the transition time for reaching a new water supply balance state after the water supply pump output bias is adjusted in the automatic state or the output changes in the manual state, thereby reducing the hidden danger of inducing secondary oscillation of the system due to being in an unstable working condition for a long time.

[0011] Compared with the prior art, the present invention has the following advantages: (1) Balancing mechanism to eliminate PID dependence The system is the first to achieve multi-pump output rebalancing after bias adjustment through the command self-balancing module (non-PID closed loop), eliminating the hysteresis and system disturbance caused by the traditional PID adjustment triggered by water supply deviation.

[0012] (2) State-adaptive bias tracking The bias module automatically switches the tracking mode according to the pump status, ensuring that the output command does not jump when switching between manual and automatic, thereby improving system stability.

[0013] (3) Generalized modular architecture It adopts a combination of standardized functional modules (PID, self-balancing calculation, bias and addition modules) to support flexible expansion of different numbers of water pumps and realize cross-control system transplantation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of module connection according to an embodiment of the present invention.

[0015] Figure 2 Schematic diagram of the connection of the instruction self-balancing calculation module according to an embodiment of the present invention.

[0016] Figure 3 Schematic diagram of the calculation module of the TS0 pin and TP0 pin of the PID module according to an embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the bias module connection according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0019] like Figure 1-4 As shown, the present invention provides a master-slave type feedwater pump command self-balancing control system for a thermal power unit, which is used for the coordinated control of multiple feedwater pumps in a thermal power plant. The control system includes a PID module, a command self-balancing calculation module, a control module for each feedwater pump, and a bias module and an addition module corresponding to each control module of each feedwater pump. The signal output end of the PID module is connected to the input end of the command self-balancing calculation module, and the output end of the command self-balancing calculation module is connected to the control module of each feedwater pump through the bias module and the addition module corresponding to each feedwater pump control module. PID module: used to calculate the average output command of all water supply pumps; that is, based on the deviation between the set water supply and the actual water supply, the average output command of all water supply pumps is calculated through PID. When all water supply pumps are in manual state, the PID module tracks the average output command of all water supply pumps manually set; The hardware part of this module is existing technology. For example, the PID module adopts the "PIDI" module in the NT6000 control system produced by Nanjing Keyuan Smart Technology Group Co., Ltd.; the specific pin correspondence of the PID module in the subsequent steps is as follows: PID module PV SP TS0 TP0 OUT_PID "PIDI" module PV SP SELT Trak Op Instruction self-balancing calculation module: Receives the average instruction output by the PID module, and calculates the self-balancing instruction based on the manual / automatic operation status of each water supply pump, the output instruction of the water supply pump in manual mode, and the bias value of the water supply pump in automatic mode, and dynamically outputs the benchmark output instruction of a single water supply pump in the automatic state; The bias module corresponding to each feed water pump control module: set up for each feed water pump, used to track or set the bias value according to the feed water pump status; Specifically, when the corresponding water supply pump is in manual state, the bias module tracks the difference between the output instruction of the water supply pump and the benchmark instruction of the output of the single water supply pump in the automatic state (that is, the output value of the instruction self-balancing calculation module); when the corresponding water supply pump is in automatic state, the output value of the bias module is determined by the input parameters received and generated by the interactive interface of the module, and the output instruction of the corresponding water supply pump is the sum of the benchmark instruction of the single water supply pump and the output value of the bias block. This method can achieve that the output value of the bias module remains unchanged and the output instruction of the water supply pump remains unchanged during the manual and automatic switching process of the water supply pump; The hardware of this module is based on existing technology. For example, the bias module uses the "TRAK" module in the NT6000 control system produced by Nanjing Sciyon Smart Technology Group Co., Ltd. The specific pin correspondence of the bias module in the subsequent steps is as follows: Bias module TS1~TSN TP1~TPN OUT_B_1~OUT_B_N "TRAK" module S T Op The adding module corresponding to each water supply pump control module is used to superimpose the reference output instruction and the offset value as the final control instruction for the automatic state of the water supply pump; The hardware part of this module is existing technology. For example, the addition module adopts the "ADD" module in the NT6000 control system produced by Nanjing Keyuan Smart Technology Group Co., Ltd.; the specific pin correspondence of the addition module in the subsequent steps is as follows: Addition module Input 1 Input 2 Output "ADD" module IN1 IN2 OUT Each water supply pump has its own control module: in manual mode, its output instruction is determined by the input parameters received and generated by the interactive interface of the module; in automatic mode, it receives and outputs the output value of the addition module, that is, the sum of the single reference instruction and the bias value, and sends it to the water supply pump regulator terminal for execution.

[0020] The hardware part of this module is existing technology. For example, the control module of each water pump adopts the "MSA" module in the NT6000 control system produced by Nanjing Keyuan Smart Technology Group Co., Ltd.; the specific pin correspondence of the control module in the subsequent steps is as follows: Control Module IN1~INN OUT_MA_1~OUT_MA_N S_MA_1~S_MA_N "MSA" module PV Op NotA A master-slave water pump command self-balancing control method for multi-actuator collaborative control includes the following steps: S1. Calculating the average output command of all actuators through a PID module; S2. Receive the average output command through a command self-balancing calculation module, and dynamically calculate the reference output command of the automatic state actuator in combination with the actuator state (manual / automatic), manual command and automatic bias value; S3. Set each actuator correspondingly through a bias module, and track or set the bias value according to the actuator state; S4. Superimpose the reference output command and the bias value through an addition module as the final control command of the automatic state actuator; wherein, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the command self-balancing module recalculates the reference output command in real time, so that other automatic state actuators are adjusted synchronously to keep the total output unchanged.

[0021] The TS0 pin and TP0 pin of the PID module are calculated as follows Figure 3 As shown in the figure, when all feedwater pumps are in manual mode, TS0 = 1; otherwise, TS0 = 0. The TP0 pin is connected to the average of the control commands output by all feedwater pumps. When TS0 = 1 (i.e., the tracking command is active), OUT_PID outputs the signal connected to the TP0 pin. Otherwise, the PID output automatically calculates the command based on the deviation between the PV and SP pin inputs. The PID module output value represents the average command output of all feedwater pumps.

[0022] The reference output command (BA_OUT) of the command self-balancing module is calculated as follows: when all water supply pumps are in automatic state, reference output command (BA_OUT) = [PID output × total number of water supply pumps - Σ (offset value of water supply pump in automatic state) - Σ (output value of water supply pump in manual state)] / number of water supply pumps in automatic state; All water supply pumps are in manual mode, and the base output command = PID output.

[0023] In step S4, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the instruction self-balancing calculation module recalculates the reference output instruction, so that the final control instructions of other automatic state actuators are adjusted synchronously to keep the total output unchanged without the need for PID closed-loop regulation.

[0024] The actuator is a water feed pump of a thermal power unit, and the system or method is used for coordinated control of multiple water feed pumps of a thermal power unit.

[0025] The command self-balancing module, bias module and addition module adopt a standardized functional module architecture and support flexible expansion of different numbers of actuators.

[0026] like Figure 1As shown, the PID module has four sets of input signals and one set of output signals relevant to this application. Input signals 1 and 2 are connected to the PV and SP pins, representing the actual water supply and the set water supply, respectively. Input signals 3 and 4 are connected to the TS0 and TP0 pins, representing the PID tracking command and tracking value, respectively. The output signal is connected to the OUT_PID pin, which is connected to the input pin BA_IN of the instruction self-balancing calculation module BALANCE, representing the input signal for the instruction self-balancing calculation.

[0027] The instruction self-balancing calculation module receives the PID instruction, calculates the self-balancing instruction according to the manual and automatic operation status of the water supply pump, and sends the output to the BA_OUT pin, which is linked to an input end of the addition module corresponding to each water supply pump.

[0028] Taking water supply pump 1 as an example, the bias module, addition module and single water supply pump control module corresponding to each water supply pump are explained.

[0029] The bias module (B_1) has two sets of input signals and one set of output signals. The input signals are connected to the TS1 and TP1 pins, representing the bias module's tracking command and tracking value, respectively. The output signal is connected to the OUT_B_1 pin and represents a component of the input control command for water pump 1.

[0030] The addition module adds the output of the B_1 module and the output of the instruction self-balancing calculation module as the input control instruction of the water supply pump 1.

[0031] A single water supply pump control module selects to receive the control instruction input from the IN1 pin or the input parameters received and generated through the module's interactive interface as the output control instruction according to its own automatic or manual status. At the same time, its manual or automatic status is output from the S_MA_1 pin as the second set of output signals.

[0032] Instruction self-balancing calculation module such as Figure 2 As shown, the construction steps are as follows: Step 3-1: Build module ① for signal selection. When S_MA_1 = 1, module ① outputs the value of the OUT_MA_1 pin; otherwise, it outputs the value of the OUT_B_1 pin. The function implemented is: when water pump 1 is in manual mode (S_MA_1 = 1), module ① outputs the output control instruction (OUT_MA_1) of water pump 1; otherwise, it outputs the output value (OUT_B_1) of the bias module corresponding to the water pump 1 control module. Modules ② and ③ are built in the same way (if the number of water pumps is greater than 3, the module number is increased accordingly). Step 3-2: Build module ④ and add the outputs of modules ①-③ (if the number of water pumps is greater than 3, the module numbers will be postponed accordingly); Step 3-3: Build module ⑤ and invert the value of S_MA_1 before outputting it. This function inverts the manual / automatic state of water pump 1 and outputs it. That is, when water pump 1 is in manual state (S_MA_1=1), module ⑤ outputs 0. Modules ⑥ and ⑦ are built in the same way (if the number of water pumps is greater than 3, the module number is postponed accordingly). Step 3-4: Build module ⑧, send the value of the PID module output to the command self-balancing calculation module, multiply it by the total number of water supply pumps, and then send it out. The function achieved is: calculate the total output command of all water supply pumps; Step 3-5: Build module 9 and subtract the output of module 8 from the output of module 4. The function achieved is: output the total reference instruction of the water pump output in the automatic state; Step 3-6: Build module ⑩ and add the outputs of modules ⑤-⑦ (if the number of water supply pumps is greater than 3, the module number will be postponed). The function achieved is: calculate the number of water supply pumps in automatic state; Step 3-7: Build module ⑪ and compare the output of module ⑩ with 0.1 and take the larger value. The function implemented is: calculate the number of water supply pumps in automatic state while preventing the denominator from being zero in the division calculation; Step 3-8: Build module ⑫ and input the manual status signal of each water supply pump. If all input terminals are 1, that is, all water supply pumps are in manual state, module ⑫ outputs 1, otherwise it outputs 0; Step 3-9: Build module ⑬ and divide the output of module ⑨ (the total baseline command for the water supply pump output in the automatic state) by the output of module ⑪ (the number of water supply pumps in the automatic state). This function is to calculate the baseline command for the output of a single water supply pump in the automatic state. Step 3-10: Build module ⑭ and select the signal channel sent to the BA_OUT pin. When module ⑫ is set to 1, module ⑭ outputs the value of BA_IN to BA_OUT; otherwise, it outputs the value of module ⑬ to BA_OUT. This implements the following functionality: When all feedwater pumps are in manual mode, the self-balancing calculation module is instructed to directly output the signal from its input terminal (BA_IN). When at least one feedwater pump is in automatic mode, the self-balancing calculation module is instructed to output the calculated baseline output command for a single feedwater pump in the automatic state.

[0033] Taking water supply pump 1 as an example, the function of the bias module B_1 corresponding to a single water supply pump is: When TS_1 = 1, the bias module is in tracking state, and the output of OUT_B_1 is TP_1. When TS_1 = 0, the bias module is not tracking, and the output signal of OUT_B_1 is determined by the input parameters received and generated by the interactive interface of the module.

[0034] Taking water pump 1 as an example, the connection diagram of TS_1 and TP_1 in the bias module B_1 corresponding to a single water pump is as follows: Figure 4 As shown, the implementation process is: When S_MA_1 = 1, TS_1 is 1, otherwise it is 0; TP_1 is the output of OUT_MA_1 minus the output of BA_OUT. The implemented functionality is: when Feedwater Pump 1 is in manual mode, the bias module tracks the difference between the output of the Feedwater Pump 1 Control Module and the output of the Command Self-Balancing Calculation Module. When Feedwater Pump 1 is in automatic mode, the bias module's output value is determined by the input parameters received and generated by the module's interactive interface.

[0035] For the addition module, taking water pump 1 as an example, the function implemented by the addition module 1 corresponding to a single water pump is to add the output of the bias module and the output of the instruction self-balancing calculation module, and send them to the input terminal IN1 of the water pump 1 control module. The manual and automatic states of a single water pump control module are determined by the input of the module's interactive interface. When switched to manual, the output control instruction of water pump 1 (OUT_MA_1) is determined by the input parameters received and generated by the module's interactive interface, and the manual state of water pump 1 (S_MA_1) is output as 1. When switched to automatic, the output control instruction of water pump 1 is the input value of IN1, and the manual state of water pump 1 (S_MA_1) is output as 0.

[0036] Take the water supply control system of a 300MW subcritical thermal power unit as an example: The unit is a subcritical drum boiler equipped with three electric speed-regulated feedwater pumps. When the rated load is above 80%, the three electric speed-regulated feedwater pumps work together to adjust the feedwater volume to achieve control of the drum water level. Each feedwater pump control module corresponds to a bias module. If the instruction self-balancing function described in the patent is not designed, if the bias output of a single feedwater pump in the automatic state is modified through the human-machine interface, the speed of the feedwater pump will change rapidly, thereby causing fluctuations in the total feedwater volume and the drum water level. Under the closed-loop regulation of the drum water level PID, the average feedwater pump speed instruction received by the three feedwater pumps changes. After a period of closed-loop adjustment, the drum water level returns to a stable state. After the optimized design, the bias output of a single feedwater pump in the automatic state is modified in the same way under the same working conditions. The main parameters of the dynamic process of the system before and after the optimized design are compared as follows: Table 1 Comparison of parameters before and after design of the water supply system command self-balancing function Maximum fluctuation range of water flow Maximum fluctuation amplitude of drum water level Time required for drum water level to stabilize Before optimization 56t / h 24mm 3min15s After optimization 25t / h 9mm 1min The data shows that the time required for the temperature of the optimized system is significantly shortened, the maximum fluctuation range of the feed water flow and the drum water level is less than 50% of the original system, and the stability maintenance ability of the feed water control loop is significantly improved, with good practicality, which is convenient for engineering implementation and promotion and application.

Claims

1. A master-slave type feedwater pump command self-balancing control system for thermal power units, used for the coordinated control of multiple feedwater pumps in thermal power plants, characterized by: It includes a PID module, a command self-balancing calculation module, a control module for each water feed pump, and a bias module and an addition module corresponding to each control module of each water feed pump; the signal output end of the PID module is connected to the input end of the command self-balancing calculation module, and the output end of the command self-balancing calculation module is connected to the control module of each water feed pump through the bias module and the addition module corresponding to each control module of each water feed pump, wherein: PID module: used to calculate the average output command of all water pumps; Instruction self-balancing calculation module: Receives the average instruction output by the PID module, and calculates the self-balancing instruction based on the manual / automatic operation status of each water supply pump, the output instruction of the water supply pump in manual mode, and the bias value of the water supply pump in automatic mode, and dynamically outputs the benchmark output instruction of a single water supply pump in the automatic state; The bias module corresponding to each feed water pump control module: set up for each feed water pump, used to track or set the bias value according to the feed water pump status; The adding module corresponding to each water supply pump control module is used to superimpose the reference output instruction and the offset value as the final control instruction for the automatic state of the water supply pump; Each water supply pump has its own control module: in manual mode, its output instruction is determined by the input parameters received and generated by the interactive interface of the module; in automatic mode, it receives and outputs the output value of the addition module, that is, the sum of the single reference instruction and the bias value, and sends it to the water supply pump regulator terminal for execution.

2. A master-slave water pump command self-balancing control method for multi-actuator coordinated control, characterized in that: The following steps are involved: S1. Calculate the average output command of all actuators through the PID module; S2 receives the average output command by the self-balancing calculation module, combined with the actuator state, manual command and automatic bias value, dynamically calculates the automatic state actuator base output command; S3. Use the bias module to set each actuator, tracking or setting the bias value based on the actuator status; S4 by adding the module to the reference output command and the bias value superimposed as the final control command of the automatic state actuator; Among them, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the instruction self-balancing module recalculates the reference output instruction in real time, so that other automatic state actuators are adjusted synchronously to keep the total output unchanged.

3. The master-slave type feedwater pump command self-balancing control system for thermal power generation units according to claim 1, characterized in that: The reference output command of the command self-balancing module is calculated as follows: when all water supply pumps are in automatic state, reference output command = [PID output × total number of water supply pumps - Σ (offset value of water supply pump in automatic state) - Σ (output value of water supply pump in manual state)] / number of water supply pumps in automatic state; When all water supply pumps are in manual mode, the base output command = PID output.

4. The master-slave water pump instruction self-balancing control method according to claim 2, characterized in that: In step S4, when the bias value of any automatic state actuator changes or the output value of the manual state actuator changes, the instruction self-balancing calculation module recalculates the reference output instruction, so that the final control instructions of other automatic state actuators are adjusted synchronously to keep the total output unchanged without the need for PID closed-loop regulation.

5. The master-slave water pump instruction self-balancing control method according to claim 2 or 4, characterized in that: The actuator is a water feed pump of a thermal power unit, and the system or method is used for coordinated control of multiple water feed pumps of a thermal power unit.

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