Thermal power plant denitration ammonia spraying automatic control method, system and equipment and storage medium

Abstract

The invention discloses a thermal power plant denitration ammonia injection automatic control method, system and device and a storage medium, and relates to the field of thermal power plant denitration ammonia injection automatic control, and the method comprises the following steps: carrying out first deviation correction on a desulfurization outlet through a PID controller; based on the start-stop state of the coal mill, carrying out second control on the ammonia spraying amount; performing third adjustment on the ammonia spraying amount in combination with the differential deviation and the set value deviation; carrying out fourth adjustment on the NOx deviation of the denitration A side outlet and the denitration B side outlet; on the basis of output results of the first deviation correction, the second control, the third adjustment and the fourth adjustment, a final given value of the ammonia injection adjusting valve is calculated; the effects that the automation level of the unit is improved, the operation burden of operators is relieved, the unit has good dynamic response quality and ideal adjusting characteristics, the fluctuation of the nitrogen oxide content is reduced, the accuracy of environmental protection parameters is improved, and the equipment failure risk of the air pre-heater system is reduced are achieved.

Description

Technical Field

[0001] The present invention relates to the field of automatic control of denitration and ammonia injection in thermal power plants, and in particular to a method, system, equipment and storage medium for automatic control of denitration and ammonia injection in thermal power plants. Background Art

[0002] As the world pays more and more attention to environmental protection, thermal power plants, as an important part of energy production, have attracted much attention for their pollutant emissions. Nitrogen oxides (NOx) are one of the main pollutants produced during the combustion process of thermal power plants. It not only causes environmental problems such as acid rain and photochemical smog, but also has great harm to human health. Therefore, effectively controlling the emission of nitrogen oxides from thermal power plants has become a key task in the industry.

[0003] At present, thermal power plants generally use selective catalytic reduction (SCR) denitrification technology to reduce nitrogen oxide emissions. The core of this technology is to inject ammonia into the flue gas. Under the action of the catalyst, ammonia reacts chemically with nitrogen oxides to reduce them to harmless nitrogen and water. The denitrification ammonia injection control system plays a vital role in the entire denitrification process. It directly determines the amount of ammonia injection, which in turn affects the denitrification efficiency and the emission concentration of nitrogen oxides. However, the existing denitrification ammonia injection control system for general thermal power plants has obvious shortcomings. Usually, the system sets a denitrification ammonia injection valve operation interface on the centralized control DCS (distributed control system) system, and the operator controls the ammonia injection amount of the denitrification system by manually adjusting the valve opening. This manual control method has many disadvantages. Because the denitrification system has significant hysteresis, when the unit load changes, the manual adjustment of the ammonia injection amount often cannot respond in time. Moreover, there may be errors in the measurement data, which will mislead the operator and make it impossible to accurately control the ammonia injection amount. This makes the nitrogen oxide content fluctuate greatly, seriously affecting the accuracy of environmental protection parameters. In more serious cases, excessive or insufficient ammonia injection may also cause corrosion, scaling, or even pipe bursts in the air preheater system equipment, which not only greatly increases the workload of operators, but also poses a threat to the safety and stability of the unit. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is to overcome the problems that the manual adjustment of the ammonia injection amount in the existing thermal power plant denitrification and ammonia injection control system cannot respond to the unit load changes in time, the nitrogen oxide content fluctuates greatly due to the error in the measurement data, affects the accuracy of environmental protection parameters, and easily causes air preheater system equipment failures, so as to achieve efficient and accurate automatic control of denitrification and ammonia injection in thermal power plants.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, an embodiment of the present invention provides a method for automatically controlling denitration and ammonia injection in a thermal power plant, comprising: Perform the first deviation correction on the desulfurization outlet through the PID controller; Based on the start and stop status of the coal mill, a second control is performed on the amount of ammonia injection; The ammonia injection amount is adjusted for the third time based on the differential deviation of the NOx at the desulfurization outlet and the deviation of the NOx at the desulfurization outlet from its set value; Performing a fourth adjustment on the NOx deviation at the outlets of the A and B sides of denitration; Based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation, the final set value of the ammonia injection regulating valve is calculated.

[0007] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The calculation of the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation includes: The output results of the first deviation correction, the second control, the third regulation and the fourth regulation are added together to obtain a final given value of the ammonia injection regulating valve; the ammonia injection amount is controlled according to the given value.

[0008] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The second control of the ammonia injection amount based on the start / stop state of the coal mill includes: The change of starting and stopping the coal mill represents the change of unit load, and the ammonia injection amount is controlled in advance; When a coal mill is started, the amount of ammonia injection is increased, and when it is stopped, the amount of ammonia injection is reduced, which is controlled by the pulse counting block.

[0009] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The first deviation correction of the desulfurization outlet by the PID controller includes: Use PID controller to correct the deviation between desulfurization outlet NOx and its set value; Continuously monitor the actual value of NOx at the desulfurization outlet actual1 , and compare it with the preset desulfurization outlet NOx setting value NOx set1 For comparison, calculate the deviation ΔNOx 1 = NOx actual1 - NOx set1 .

[0010] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The first deviation correction of the desulfurization outlet by the PID controller also includes: When ΔNOx 1 >0, the proportional P action and integral I action of the PID controller are activated, issuing a command to increase the output; when ΔNOx 1 When <0, an instruction to reduce output is issued.

[0011] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The third adjustment of the ammonia injection amount based on the differential deviation of the desulfurization outlet NOx and the deviation of the desulfurization outlet NOx from its set value includes: The differential deviation of NOx at the desulfurization outlet and its deviation from the set value are considered comprehensively to jointly adjust the ammonia injection amount; Analyze the differential deviation ΔNOx of desulfurization outlet NOx diff , when ΔNOx diff <C 1 And ΔNOx diff <C 2 When the trigger pulse count decreases, the amount of ammonia sprayed is reduced, where C 1 and C 2 is a pre-set threshold; When ΔNOx diff >C 1 And ΔNOx diff >C 2 When the trigger pulse count increases, the amount of ammonia sprayed increases.

[0012] As a preferred solution for the automatic control method of denitration and ammonia injection in thermal power plants, wherein: The fourth adjustment of the NOx deviation at the outlets of the denitration A and B sides includes: PID adjustment is performed on the deviation between the NOx at the outlet of the A side of denitrification and the NOx at the outlet of the B side; Monitor the actual value of NOx at the outlet of denitrification A side actualA and B side outlet NOx actual value NOx actualB , calculate the deviation ΔNOx 2 =NOx actualA -NOx actualB ; When ΔNOx 2 >0, the proportional P action and integral I action of the PID controller are activated, issuing a command to increase the output; when ΔNOx 2 When <0, a command to reduce output is issued.

[0013] In a second aspect, an embodiment of the present invention provides an automatic control system for denitration and ammonia injection in a thermal power plant, comprising: A first deviation correction module, used for performing a first deviation correction on the desulfurization outlet through a PID controller; A second control module is used to perform a second control on the ammonia injection amount based on the start and stop state of the coal mill; A third adjustment module is used to perform a third adjustment on the ammonia injection amount based on the differential deviation of the desulfurization outlet NOx and the deviation of the desulfurization outlet NOx from its set value; A fourth adjustment module, used for performing a fourth adjustment on the NOx deviation at the outlets of the denitration A and B sides; The given value calculation module is used to calculate the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation.

[0014] In a third aspect, an embodiment of the present invention provides an electronic device, including: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the one or more programs are executed by the one or more processors, the one or more processors implement the automatic control method for denitrification and ammonia injection in a thermal power plant as described in any embodiment of the present invention.

[0015] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, can implement the automatic control method for denitrification and ammonia injection in a thermal power plant.

[0016] Beneficial effects of the present invention: The present invention adopts a control strategy consisting of four parts, namely, PID control of the NOx at the desulfurization outlet and its set value deviation, early intervention control of the ammonia injection amount according to the start-stop state change of the coal mill, adjustment of the ammonia injection amount in combination with the NOx differential deviation at the desulfurization outlet and the set value deviation, and PID adjustment of the NOx deviation at the A and B side outlets of the denitrification, and the weighted addition of the output results of the four parts to form the final ammonia injection valve set value to control the ammonia injection amount, thereby improving the automation level of the unit, reducing the operating burden of the operating personnel, enabling the unit to have good dynamic response quality and ideal adjustment characteristics, reducing the fluctuation of nitrogen oxide content, improving the accuracy of environmental protection parameters, and reducing the risk of equipment failure in the air preheater system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0018] Figure 1 It is an overall flow chart of the automatic control method for denitration and ammonia injection in a thermal power plant according to the present invention. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0020] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a method for automatically controlling denitration and ammonia injection in a thermal power plant, comprising: S1: Perform the first deviation correction on the desulfurization outlet through the PID controller; S2: Based on the start and stop status of the coal mill, a second control is performed on the ammonia injection amount; S3: Combining the differential deviation and the set value deviation, a third adjustment is made to the ammonia injection amount; S4: Performing a fourth adjustment on the NOx deviation at the outlets of the denitration A and B sides; S5: Calculate the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation.

[0021] It should be noted that, through steps S1-S5, the control strategy is mainly composed of four parts. The first part is PID control, which mainly corrects the deviation between the NOx at the desulfurization outlet and the set value of the NOx at the desulfurization outlet; the second part is the start-stop mill control loop, which mainly represents the change of the unit load according to the change of the start-stop mill, thereby changing the amount of ammonia injection, intervening in control in advance, overcoming the delay of sampling, and ensuring the stability of the NOx at the desulfurization outlet; the third part is the differential deviation of the NOx at the desulfurization outlet and the deviation of the set value of the NOx at the desulfurization outlet; the fourth part is the PID adjustment of the deviation between the NOx at the outlet of the denitrification A side and the NOx at the outlet of the denitrification B side; the sum of these four parts constitutes the final set value of the ammonia injection regulating valve to control the ammonia injection amount.

[0022] Example 2, reference Figure 1 , which is an embodiment of the present invention, provides a method for automatically controlling denitration and ammonia injection in a thermal power plant based on the previous embodiment, comprising: In this embodiment, the first deviation correction of the desulfurization outlet by the PID controller in the above step S1 includes: The PID controller is used to correct the deviation between the desulfurization outlet NOx and its set value.

[0023] Specifically, when the denitrification system of a thermal power plant is running, the actual value of NOx at the desulfurization outlet is continuously monitored. actual1 , and compare it with the preset desulfurization outlet NOx setting value NOx set1 For comparison, calculate the deviation ΔNOx 1 = NOx actual1 -NOx set1 ; When ΔNOx 1 >0 (positive deviation), the proportional P action and integral I action of the PID controller are activated, and an instruction to increase the output of ammonia injection is issued; when ΔNOx 1 When <0 (negative deviation), a command to reduce the amount of ammonia spray output is issued. This part of the output is recorded as Output 1 This step is the main control link, the output coefficient K 1 =1.

[0024] In another possible implementation, in addition to monitoring the actual value of NOx at the desulfurization outlet, the first deviation correction can also introduce other relevant sensor data, such as flue gas flow, temperature, oxygen content, etc. These data are processed by a data fusion algorithm (such as Kalman filtering) to obtain more accurate NOx generation and emission information. Then, PID correction is performed based on the deviation between the fused data and the set value. For example, at high flue gas flow, even if the NOx concentration is the same, the actual NOx emission will be greater. At this time, the adjustment range of the ammonia injection amount can be appropriately increased.

[0025] In this embodiment, the second control of the ammonia injection amount based on the start / stop state of the coal mill in the above step S2 includes: The change of starting and stopping the coal mill represents the change of unit load, and the ammonia injection amount is controlled in advance; Specifically, when a coal mill is started, the amount of ammonia injection is increased, and when it is stopped, the amount of ammonia injection is reduced. The pulse counting block is used to control the output, and the output result is multiplied by the coefficient f corresponding to the actual load. 2 (L), L is the actual load, the coefficient is obtained through multiple tests, this part of the output is recorded as Output 2 , is the secondary control loop, output coefficient K 2 The value range is [0.2,0.5], and the specific value is determined through multiple tests based on actual conditions.

[0026] It should be noted that when a thermal power plant is in operation, the actual load L of the unit changes dynamically. Under different load conditions, the amount of nitrogen oxides produced by fuel combustion is different, and the working characteristics of the denitrification system are also different. Simply increasing or decreasing the amount of ammonia injection based on the start and stop of the coal mill may not accurately meet the denitrification needs under different loads. Introducing the coefficient f corresponding to the actual load L 2(L) is used to correct the ammonia injection adjustment output result calculated based on the start and stop status of the coal mill, so that the adjustment of the ammonia injection amount is more in line with the actual load of the current unit, thereby improving the accuracy of denitrification control.

[0027] In another possible implementation, f is determined 2 (L), the adjustment of ammonia injection amount when the coal mill is started and stopped and the corresponding denitrification effect data can be recorded under various unit load conditions. Then, these data are deeply analyzed and processed to find the corresponding law between the actual load L and the appropriate ammonia injection adjustment coefficient, so as to determine the function f 2 (L). This function reflects how to adjust the output result calculated based on the start and stop status of the coal mill in order to achieve the best denitrification effect under different loads.

[0028] According to the start and stop status of the coal mill, the pulse counting block is used to control and calculate the corresponding output result, and then multiply it by the coefficient f 2 (L), the output after load correction can be obtained 2 This corrected output will be used in the calculation of the final ammonia injection valve setpoint, making the control of ammonia injection more scientific and reasonable. For example, when the unit is running at high load, the amount of nitrogen oxides produced increases. 2 (L) may be a coefficient greater than 1, which will increase the adjustment range of the ammonia injection amount after multiplying the output result; when the unit is operating at low load, f 2 (L) may be less than 1, thereby reducing the adjustment range of the ammonia injection amount and avoiding waste caused by excessive ammonia injection or causing other problems.

[0029] Output coefficient K 2 The value range is [0.2,0.5], which further affects Output 2 Scaling is performed to determine the weight of this part of the control strategy in the final calculation of the ammonia injection valve set value. Since this part belongs to the secondary control loop, by adjusting K 2 The specific value of K can balance the influence of each control part on the final ammonia injection amount, making the entire denitrification ammonia injection automatic control system more stable and reliable. 2 The value needs to be determined based on actual conditions and through multiple tests to adapt to the specific operating conditions and denitrification requirements of different thermal power plants.

[0030] In another possible implementation, the second control can use load forecasting technology in addition to judging the unit load change according to the start-up and stop status of the coal mill. For example, the unit historical load data is analyzed and modeled using time series analysis (such as ARIMA model) to predict the unit load change in the future. The ammonia injection amount is adjusted in advance according to the prediction results, rather than waiting until the coal mill is started and stopped before reacting.

[0031] In this embodiment, the third adjustment of the ammonia injection amount in step S3 in combination with the differential deviation and the set value deviation includes: The differential deviation of NOx at the desulfurization outlet and its deviation from the set value are considered comprehensively to jointly adjust the ammonia injection amount; Specifically, the differential deviation ΔNOx of the desulfurization outlet NOx is analyzed. diff When ΔNOx diff <C 1 And ΔNOx diff <C 2 When (C 1 and C 2 is a preset threshold), triggering pulse counting to reduce the amount of ammonia injection; when ΔNOx diff >C 1 And ΔNOx diff >C 2 When ΔNOx diff Between C 1 and C 2 When the current ammonia injection amount is kept unchanged, the output of this regulation process is multiplied by the coefficient f corresponding to the actual load. 3 (L), and obtain the output result of the third adjustment; the output in this adjustment process refers to the pulse adjustment amount generated based on the comparison between the differential deviation ΔNOxdiff and the threshold value, which is a discrete ammonia injection adjustment instruction, and is essentially an adjustment amount embodied in the form of a pulse signal; where L is the actual load, the coefficient f 3 (L) Obtain the functional relationship through multiple experiments; record the output result of the third adjustment as Output 3 , is the secondary control loop, output coefficient K 3 The value range is [0.2,0.5], and the specific value is determined through multiple tests based on actual conditions.

[0032] It should be noted that during the operation of a thermal power plant, the actual load L of the unit is constantly changing, and under different load conditions, the amount of nitrogen oxides produced in the flue gas and the working characteristics of the denitrification system will be different. Therefore, it may not be accurate to determine the adjustment range of the ammonia injection amount based solely on the differential deviation of the desulfurization outlet NOx and the set value deviation. By introducing the coefficient f corresponding to the actual load L 3(L) The output calculated based on the deviation can be corrected so that the adjustment of the ammonia injection amount is more in line with the actual demand under the current unit load, thereby improving the accuracy of denitrification control.

[0033] In another possible implementation, when determining f 3 (L), a large number of tests can be carried out under different unit load conditions to record the changes in NOx at the desulfurization outlet, the adjustment of the ammonia injection amount, and the final denitrification effect. Then, these data are analyzed and processed to find the corresponding relationship between the actual load L and the appropriate ammonia injection adjustment coefficient, thereby obtaining the function f 3 (L). This function reflects how to adjust the output calculated based on the deviation in order to achieve the best denitrification effect under different loads.

[0034] After generating the corresponding pulse adjustment amount according to the differential deviation of NOx at the desulfurization outlet and the set value deviation, multiply it by the coefficient f 3 (L), we can get the output result after load correction. 3 This corrected output will be incorporated into the calculation of the final ammonia injection valve setpoint, making the control of ammonia injection more scientific and reasonable. For example, when the unit is running at high load, the amount of nitrogen oxides produced may increase. 3 (L) may be a coefficient greater than 1, which will increase the adjustment range of ammonia injection amount when multiplied by the output; when the unit is running at low load, f 3 (L) may be less than 1, thereby reducing the adjustment range of the ammonia injection amount and avoiding waste or other adverse effects caused by excessive ammonia injection.

[0035] Output coefficient K 3 The value range is [0.2,0.5], which further affects Output 3 Scaling is performed to determine the weight of this part of the control strategy in the calculation of the final ammonia injection valve setpoint. Since this part is a secondary control loop, by adjusting K 3 The specific value of K can balance the influence of each control part on the final ammonia injection amount, making the entire denitrification ammonia injection automatic control system more stable and reliable. 3 The value is also determined based on actual conditions and through multiple tests to adapt to the specific operating conditions and denitrification requirements of different thermal power plants.

[0036] In another possible implementation, in addition to considering the differential deviation and set value deviation of NOx at the desulfurization outlet, the third adjustment may also introduce other deviation information, such as the cumulative deviation of NOx emissions, the comparison deviation with other similar units, etc. These deviations are weighted and integrated, and the ammonia injection amount is adjusted according to the integrated deviation. For example, when the cumulative deviation is large, the adjustment range of the ammonia injection amount is appropriately increased to reduce the cumulative error as soon as possible. The principal component analysis (PCA) and other methods can be used to reduce the dimensionality of multiple deviation variables, extract the main deviation information, and then adjust according to these main deviations to reduce the coupling effect between variables.

[0037] In this embodiment, the fourth adjustment of the NOx deviation at the outlets of the denitration A and B sides in the above step S4 includes: PID adjustment is performed on the deviation between the NOx at the outlet of the A side of denitrification and the NOx at the outlet of the B side.

[0038] Specifically, monitor the actual value of NOx at the outlet of denitrification side A. actualA and B side outlet NOx actual value NOx actualB , calculate the deviation ΔNOx 2 =NOx actualA -NOx actualB When ΔNOx 2 >0 (positive deviation), the proportional P action and integral I action of the PID controller are activated, issuing a command to increase the output; when ΔNOx 2 When <0 (negative deviation), a command to reduce output is issued. This part of the output is recorded as Output 4 , is the secondary control loop, output coefficient K 4 The value range is [0.2,0.5], and the specific value is determined through multiple tests based on actual conditions.

[0039] In another possible implementation, the fourth adjustment can take into account the dynamic characteristic differences between the A and B sides of denitration, such as pipeline resistance, catalyst activity, etc. By establishing a dynamic compensation model, the concentration deviation between the outlet NOx of the A side of denitration and the outlet NOx of the B side is compensated in real time. For example, when the pipeline resistance of the A side is large, the NOx emission of the A side may be relatively high. At this time, the amount of ammonia injection on the A side can be appropriately increased for compensation. The dynamic characteristic parameters of the A and B sides can be estimated in real time by online identification technology, and the compensation amount can be adjusted in time according to the parameter changes to improve the accuracy of the adjustment.

[0040] In this embodiment, in the above step S5, based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation, calculating the final given value of the ammonia injection regulating valve includes: The output results of the first deviation correction, the second control, the third regulation and the fourth regulation are added together to obtain a final given value of the ammonia injection regulating valve.

[0041] Specifically, the final given value S of the ammonia injection regulating valve is calculated by the formula, which is expressed as: S=K 1 *Output 1 + K 2 *Output 2 + K 3 *Output 3 + K 4 *Output 4 The amount of ammonia injection is controlled according to a given value, thereby realizing automatic control of ammonia injection for denitrification in thermal power plants.

[0042] Embodiment 3, the above is a schematic scheme of the automatic control method for denitration and ammonia injection in a thermal power plant of this embodiment. It should be noted that the technical scheme of the automatic control system for denitration and ammonia injection in a thermal power plant and the technical scheme of the automatic control method for denitration and ammonia injection in a thermal power plant mentioned above belong to the same concept. For details not described in detail in the technical scheme of the automatic control system for denitration and ammonia injection in a thermal power plant of this embodiment, please refer to the description of the technical scheme of the automatic control method for denitration and ammonia injection in a thermal power plant mentioned above.

[0043] This embodiment also provides a thermal power plant denitrification and ammonia injection automatic control system, including: A first deviation correction module, used for performing a first deviation correction on the desulfurization outlet through a PID controller; A second control module is used to perform a second control on the ammonia injection amount based on the start and stop state of the coal mill; A third adjustment module is used to perform a third adjustment on the ammonia injection amount based on the differential deviation of the desulfurization outlet NOx and the deviation of the desulfurization outlet NOx from its set value; A fourth adjustment module, used for performing a fourth adjustment on the NOx deviation at the outlets of the denitration A and B sides; The given value calculation module is used to calculate the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation.

[0044] This embodiment also provides an electronic device, which is applicable to the automatic control method of denitration and ammonia injection in a thermal power plant, and includes: Memory and processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the automatic control method for denitrification and ammonia injection in a thermal power plant as proposed in the above embodiment.

[0045] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the automatic control method for denitrification and ammonia injection in a thermal power plant proposed in the above embodiment is implemented.

[0046] The storage medium proposed in this embodiment and the automatic control method for denitrification and ammonia injection in a thermal power plant proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for automatically controlling denitration and ammonia injection in a thermal power plant, characterized in that: include: Perform the first deviation correction on the desulfurization outlet through the PID controller; Based on the start and stop status of the coal mill, a second control is performed on the amount of ammonia injection; The ammonia injection amount is adjusted for the third time based on the differential deviation of the NOx at the desulfurization outlet and the deviation of the NOx at the desulfurization outlet from its set value; Performing a fourth adjustment on the NOx deviation at the outlets of the A and B sides of denitration; Based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation, the final set value of the ammonia injection regulating valve is calculated.

2. The automatic control method for denitrification and ammonia injection in a thermal power plant according to claim 1, characterized in that: The calculation of the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation includes: The output results of the first deviation correction, the second control, the third regulation and the fourth regulation are added together to obtain a final given value of the ammonia injection regulating valve; the ammonia injection amount is controlled according to the given value.

3. The automatic control method for denitration and ammonia injection in a thermal power plant according to claim 2, characterized in that: The second control of the ammonia injection amount based on the start / stop state of the coal mill includes: The change of starting and stopping the coal mill represents the change of unit load, and the ammonia injection amount is controlled in advance; When a coal mill is started, the amount of ammonia injection is increased, and when it is stopped, the amount of ammonia injection is reduced, which is controlled by the pulse counting block.

4. The automatic control method for denitration and ammonia injection in a thermal power plant according to claim 3, characterized in that: The first deviation correction of the desulfurization outlet by the PID controller includes: Use PID controller to correct the deviation between desulfurization outlet NOx and its set value; Continuously monitor the actual value of NOx at the desulfurization outlet actual1 , and compare it with the preset desulfurization outlet NOx setting value NOx set1 For comparison, calculate the deviation ΔNOx1 = NOx actual1 - NOx set1 .

5. The automatic control method for denitration and ammonia injection in a thermal power plant according to claim 4, characterized in that: The first deviation correction of the desulfurization outlet by the PID controller also includes: When ΔNOx1>0, the proportional P action and integral I action of the PID controller are activated, and an instruction to increase the output is issued; when ΔNOx1<0, an instruction to reduce the output is issued.

6. The automatic control method for denitration and ammonia injection in a thermal power plant according to claim 5, characterized in that: The third adjustment of the ammonia injection amount based on the differential deviation of the desulfurization outlet NOx and the deviation of the desulfurization outlet NOx from its set value includes: The differential deviation of NOx at the desulfurization outlet and its deviation from the set value are considered comprehensively to jointly adjust the ammonia injection amount; Analyze the differential deviation ΔNOx of desulfurization outlet NOx diff , when ΔNOx diff <C1 and ΔNOx diff When <C2, the trigger pulse count reduces the amount of ammonia injection, where C1 and C2 are pre-set thresholds; When ΔNOx diff >C1 and ΔNOx diff >C2, the trigger pulse count increases the amount of ammonia sprayed.

7. The automatic control method for denitrification and ammonia injection in a thermal power plant according to claim 6, characterized in that: The fourth adjustment of the NOx deviation at the outlets of the denitration A and B sides includes: PID adjustment is performed on the deviation between the NOx at the outlet of the A side of denitrification and the NOx at the outlet of the B side; Monitor the actual value of NOx at the outlet of denitrification A side actualA and B side outlet NOx actual value NOx actualB , calculate the deviation ΔNOx2=NOx actualA -NOx actualB ; When ΔNOx2>0, the proportional P action and the integral I action of the PID controller are activated, and an instruction to increase the output is issued; when ΔNOx2<0, an instruction to reduce the output is issued.

8. An automatic control system for denitration and ammonia injection in a thermal power plant, using the method according to any one of claims 1 to 7, characterized in that: include: A first deviation correction module, used for performing a first deviation correction on the desulfurization outlet through a PID controller; A second control module is used to perform a second control on the ammonia injection amount based on the start and stop state of the coal mill; A third adjustment module is used to perform a third adjustment on the ammonia injection amount based on the differential deviation of the desulfurization outlet NOx and the deviation of the desulfurization outlet NOx from its set value; A fourth adjustment module, used for performing a fourth adjustment on the NOx deviation at the outlets of the denitration A and B sides; The given value calculation module is used to calculate the final given value of the ammonia injection regulating valve based on the output results of the first deviation correction, the second control, the third regulation and the fourth regulation.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions, when executed by a processor, implement the steps of the method according to any one of claims 1 to 7.

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