Flue gas denitration control method based on sliding integral and differential duration enablement

Abstract

The present application relates to flue gas denitration control method based on sliding integral and differential duration enablement, and relates to the field of automatic control technology. The method comprises: performing adaptive pretreatment on original concentration data to obtain nitrogen oxide smooth observation value and ammonia escape smooth observation value; then calculating sliding integral and differential duration; checking whether the flue gas denitration system is in a locked state, if not, judging whether the ammonia escape priority criterion is met based on the ammonia escape smooth observation value; if met, triggering the adjustment instruction; if not met, judging whether the nitrogen oxide regular adjustment criterion is met based on the sliding integral and differential duration, and if met, triggering the adjustment instruction; when the adjustment instruction is triggered, using an improved PID algorithm with ammonia escape constraint term to calculate the opening increment; after executing the valve opening adjustment according to the opening increment, activating the flue gas denitration system locked state and maintaining for a preset time length. The present application can ensure the precise control of ammonia injection amount.

Description

Technical Field

[0001] This invention relates to the field of automation control technology, and in particular to a flue gas denitrification control method based on the starting control of sliding integral and derivative duration. Background Technology

[0002] In the industrial production sector, flue gas denitrification systems (including types such as SCR selective catalytic reduction and SNCR selective non-catalytic reduction) in coal-fired power plants, industrial boilers, and waste incineration power plants are typical control objects with large time lag, strong disturbances, and nonlinear characteristics. Their stable and efficient operation is crucial to meeting environmental protection requirements.

[0003] Currently, PID control strategies are commonly used in industrial control sites. The concentration of nitrogen oxides (NOx) at the chimney outlet is collected by DCS and compared with the set value. After calculating the deviation, the PID algorithm outputs commands to adjust the opening of the ammonia or urea injection valve, thereby achieving denitrification control.

[0004] However, due to the high temperature and dust environment at the inlet of the denitrification reactor, the inlet NOx sensor is not only expensive, but also prone to clogging and damage, resulting in high maintenance costs. Therefore, most power plants only install NOx analyzers at the outlet of the denitrification reactor. This makes it impossible for the control system to obtain the real-time changes in the inlet NOx concentration, and it loses the basis for feedforward control. It can only rely on the outlet data for feedback control. Coupled with the large lag characteristics of the system itself, this greatly increases the difficulty of control.

[0005] When dealing with such systems, conventional PID control strategies, in pursuit of response speed, employ high-frequency fixed sampling and adjustment periods. This indiscriminately introduces transient disturbances from the signal into the control loop, making it difficult to accurately identify transient fluctuations and the true trend of changes in operating conditions. Consequently, the controller makes erroneous forced adjustments to high-frequency disturbances under steady-state conditions, causing system output oscillations and divergence. This also exacerbates ineffective reciprocating motions and mechanical wear of the control valve. Furthermore, the integral term of conventional PID control strategies is a linear accumulation of deviations across the entire time domain. In flue gas denitrification systems with large time lag, the controlled variable cannot respond within the time lag after the control action is issued. The integral term will continue to accumulate errors, leading to excessive expansion of the integral value. When the controlled variable finally responds, the excessively large integral action will cause severe overshoot, and the system will have difficulty recovering from saturation quickly, resulting in divergence in the adjustment process.

[0006] Existing technologies that use instantaneous differential to predict trends can capture extremely large rates of change under conditions of frequent NOx concentration fluctuations. However, these rates of change often reflect the amplitude of the disturbance rather than the trend, causing the differential term to lose its predictive function and instead become a source of interference for system oscillations due to overreaction to fluctuations. In addition, the calculation of control commands faces nonlinear constraints. Large-amplitude adjustments can easily lead to overshoot oscillations, while fine adjustments with small amplitudes are limited by the mechanical precision of the control valve, causing the actuator to fail. This makes it impossible to effectively implement the theoretically calculated control precision at the physical level. Furthermore, traditional single-variable control strategies only focus on NOx concentration control and lack real-time high-priority constraints on ammonia escape. In the process of pursuing rapid NOx compliance, excessive injection of reducing agent can easily lead to excessive ammonia escape concentration, causing secondary pollution and the risk of ammonium bisulfate blockage in the air preheater.

[0007] These problems together make it difficult for existing automatic control systems to meet increasingly stringent environmental protection requirements. The system has a low rate of automatic operation, and operators have to frequently intervene manually, or even be forced to switch to manual mode for a long time to adjust based on experience. This not only greatly increases the operating load, but also makes it difficult to ensure the accurate control of ammonia injection. Summary of the Invention

[0008] Therefore, it is necessary to provide a flue gas denitrification control method based on sliding integral and derivative duration control that can ensure precise control of ammonia injection and reduce the operational burden, in order to address the above-mentioned technical problems.

[0009] A flue gas denitrification control method based on sliding integral and derivative duration start-up control, the method comprising:

[0010] Step 1: Acquire raw concentration data in real time;

[0011] Step 2: Perform adaptive preprocessing on the original concentration data to obtain smoothed observations, which include smoothed observations of nitrogen oxides and smoothed observations of ammonia escape.

[0012] Step 3: Calculate the sliding integral based on the cumulative deviation between the smoothed nitrogen oxide observation value and the set target value within a preset time window; calculate the differential duration based on the net cumulative time of the smoothed nitrogen oxide observation value changing along the dominant trend direction.

[0013] Step 4: Verify whether the flue gas denitrification system is in a locked state. If not, determine whether the ammonia slip priority criterion is met based on the ammonia slip smoothing observation value in Step 2. If it is met, trigger the adjustment command. If it is not met, determine whether the nitrogen oxide conventional adjustment criterion is met based on the sliding integral and derivative duration in Step 3. If it is met, trigger the adjustment command. If neither is met or the flue gas denitrification system is in a locked state, return to Step 1.

[0014] Step 5: When the adjustment command is triggered, the improved PID algorithm with ammonia escape constraint term is used to calculate the opening increment of the ammonia injection or urea injection valve; after the valve opening is adjusted according to the opening increment, the flue gas denitrification system is activated and maintained for a preset time, and then the process returns to step 1.

[0015] Compared with existing technologies, the flue gas denitrification control method based on sliding integral and differential duration provided by this invention has the following advantages:

[0016] 1. Through adaptive preprocessing of the original concentration data, outliers in the data are effectively corrected and noise caused by field disturbances is smoothed out, avoiding interference of the original data fluctuations on the control logic, and providing stable and reliable basic data for the accurate calculation of subsequent control indicators.

[0017] 2. To address the large time lag characteristic commonly found in denitrification systems, the sliding integral is calculated using the accumulated deviation within a preset time window, replacing the full-time integral of traditional PID control. This fundamentally avoids the overshoot and excessive fluctuations caused by the continuous accumulation of integrals during conventional PID ammonia injection regulation in systems with large time lag. Simultaneously, by calculating the derivative duration using the net accumulated time in the dominant trend direction, transient disturbances and actual operating conditions can be accurately distinguished, reducing erroneous adjustments by the controller to invalid fluctuations, improving the anti-interference capability of the control logic, and ensuring that ammonia injection regulation is triggered only when the operating conditions of the system with large time lag undergo substantial changes, thus achieving precise matching of the ammonia injection quantity.

[0018] 3. By prioritizing ammonia escape as the pre-conditioning logic for regulation, equipment safety and secondary pollution risk control are given priority, effectively avoiding the problem of excessive ammonia injection in pursuit of NOx concentration compliance. Combined with the verification of system lockout status, frequent invalid valve actions are further reduced, mechanical wear of actuators is reduced, and equipment service life is extended. At the same time, the need for manual intervention due to frequent system fluctuations is reduced, significantly alleviating the operational burden on operators.

[0019] 4. An improved PID algorithm incorporating ammonia slip constraints was used to achieve multi-objective coordinated control of denitrification efficiency, equipment safety, and operational economy. The application of sliding integrals improved adjustment accuracy, while the conditional intervention of the ammonia slip constraint ensured denitrification performance while enhancing system safety and environmental compliance. Stable system operation can be maintained without frequent manual adjustments to ammonia injection parameters, guaranteeing precise control of ammonia injection volume and further reducing operational complexity. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention, and those skilled in the art can obtain other related drawings based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the flue gas denitrification control method based on sliding integral and derivative duration in Example 1.

[0022] Figure 2 This is a structural block diagram of the flue gas denitrification control device based on the sliding integral and differential duration in Example 2;

[0023] Figure 3 This is a diagram of the internal structure of the computer device in Example 3.

[0024] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that in this invention, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] It is understood that the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] Example 1

[0030] like Figure 1As shown, this embodiment provides a flue gas denitrification control method based on sliding integral and derivative duration control, including the following steps:

[0031] Step 1: Acquire raw concentration data in real time.

[0032] Step 2: Adaptive preprocessing is performed on the original concentration data to obtain smoothed observations, which include smoothed observations of nitrogen oxides and smoothed observations of ammonia escape.

[0033] Step 3: Calculate the sliding integral using the cumulative deviation between the smoothed nitrogen oxide observation and the set target value within a preset time window; calculate the differential duration using the net cumulative time of the smoothed nitrogen oxide observation changing along the dominant trend direction.

[0034] Step 4: Verify whether the flue gas denitrification system is in a locked state. If not, use the ammonia slip smoothing observation value in Step 2 as a basis to determine whether the ammonia slip priority criterion is met. If it is met, trigger the adjustment command. If it is not met, use the sliding integral and derivative duration in Step 3 as a basis to determine whether the nitrogen oxide conventional adjustment criterion is met. If it is met, trigger the adjustment command. If neither is met or the flue gas denitrification system is in a locked state, return to Step 1.

[0035] Step 5: When the adjustment command is triggered, the improved PID algorithm with ammonia escape constraint term is used to calculate the opening increment of the ammonia injection or urea injection valve; after the valve opening is adjusted according to the opening increment, the flue gas denitrification system is activated and maintained for a preset time, and then the process returns to step 1.

[0036] The flue gas denitrification control method based on sliding integral and derivative duration provided by this invention accurately distinguishes transient disturbances from real operating condition changes through a closed-loop process of adaptive data preprocessing, core control index calculation, hierarchical logic trigger arbitration, and improved PID regulation execution. This avoids the overshoot and malfunction problems of traditional PID control, while prioritizing the management of ammonia escape risk, thus achieving multiple unifications of denitrification efficiency, equipment safety, and operational economy.

[0037] In the specific implementation of step 1, the original concentration data are the nitrogen oxide (NOx) concentration data and ammonia slip concentration data at the outlet of the denitrification reactor. This data is collected in real time by an analyzer array installed at the outlet of the denitrification reactor. The method proposed in this invention operates entirely within a DCS or PLC controller.

[0038] In this step, the real-time nature of data acquisition provides a fundamental guarantee for subsequent control processes, avoiding inaccurate control decisions due to data lag and ensuring timely response to changes in operating conditions.

[0039] In the specific implementation of step 2, the core purpose of adaptive preprocessing is to eliminate outliers and spike noise in the field signal, including the following steps:

[0040] Step 201, preset the effective physical threshold range corresponding to the original concentration data as follows: This range is determined based on the actual operating conditions of the flue gas denitrification system and the measurement range of the instruments.

[0041] Step 202, set The original concentration data at time 1 is If the raw concentration data obtained in step 1 exceeds the corresponding effective physical threshold range, i.e. If so, the original concentration data is determined to be an outlier.

[0042] Step 203: For the identified outliers, a pre-set time window is used. The corrected data sequence is obtained by replacing the sliding median within the range. In the formula, In the pre-set time window The inner part represents the moving median, and the replaced part represents the corrected data sequence; This represents the index of the backtracking sampling point.

[0043] Step 204, according to the preset window length For the corrected data sequence The smoothed observations are obtained by performing a moving average calculation, expressed as follows:

[0044] ;

[0045] In the formula, express Smoothed observations at any given time; Indicates the preset window length; Indicates the index of the sampling point within the moving average window; express Backtracking to the index at any time The corresponding corrected data sequence.

[0046] It is worth noting that the preceding preset time window The length is determined based on the sampling cycle of the flue gas denitrification system and the frequency of on-site disturbances; the preset window length is... Less than the preset time window of the preceding sequence The window length setting ensures both the reliability of outlier replacement and the real-time smoothness of processing.

[0047] This step, through the processing methods of "threshold limiting, moving median filtering, and moving average filtering," not only removes extreme outliers caused by instrument malfunctions or soot blowing operations, but also smooths high-frequency random noise while preserving the true operating condition trend characteristics, providing a reliable data foundation for the accurate calculation of subsequent core control indicators.

[0048] In the specific implementation of step 3, the sliding integral and differential durations are calculated in parallel. Specifically, the sliding integral is calculated based on the cumulative deviation between the smoothed observation value of nitrogen oxides and the set target value within a preset time window. The calculation expression is as follows:

[0049] ;

[0050] In the formula, express Sliding integral at any time; The fixed time window length represents the sliding integral. Indicates the sampling time; express Smoothed observations at any given time; This indicates the target value for nitrogen oxides; This indicates the total number of sampling points included in the sliding time window; Indicates instantaneous deviation, ; Indicates the sampling period; This represents the step size index within the sliding integral window. This is different from the full-time integral of a traditional PID controller. Unlike other methods, the sliding integral proposed in this invention only focuses on the cumulative deviation within a recent fixed time window, thus avoiding the overshoot problem caused by integral saturation from the root.

[0051] The differential duration is calculated using the net cumulative time of the smoothed nitrogen oxide observations changing along the dominant trend direction, including:

[0052] Real-time monitoring of the differential sign of smoothed observations of nitrogen oxides ,in, for Time and The difference between smoothed observations of nitrogen oxides at time intervals, where the difference is normal. If the difference is negative, then At the same time, maintain the current dominant trend direction, that is The dominant trend direction at any moment and the peak accumulation time in the current dominant trend direction .

[0053] when and When consistent, net duration Positive accumulation and updating of peak accumulation time ;when and Conversely, then for Perform reverse deduction. The reversal determination is not based on a simple zero-crossing point, but on the ratio of the deduction amount to the peak value. Let... To determine the reversal threshold, the transient duration is first calculated based on the differential sign and the dominant trend direction, expressed as:

[0054] ;

[0055] In the formula, express The duration of the transient state at a given moment; express The net duration of nitrogen oxide emissions at any given time; The sampling period is matched with the control response speed of the flue gas denitrification system and can be flexibly adjusted according to the frequency of on-site disturbances to optimize the trend recognition accuracy. express The differential sign of the smoothed observation of nitrogen oxides at time; express The dominant trend direction at any given moment.

[0056] Subsequently, by comparing the transient duration with the peak accumulation time, it was verified whether the trend reversal condition, i.e., the reverse deduction amount, was met. Whether it exceeds a certain proportion of the cumulative peak value in the dominant direction is expressed as:

[0057] ;

[0058] In the formula, This indicates the result of the reverse condition check; express The cumulative time of peaks that dominate the trend direction at any given moment; This indicates the threshold for determining the trend reversal ratio.

[0059] Based on the inversion condition check results The truth value of the value is determined by combining the differential sign, transient duration, and dominant trend direction to calculate the differential duration, expressed as:

[0060] ;

[0061] In the formula, express The dominant trend direction at any given moment; express The net duration of nitrogen oxide emissions at any given time; express The cumulative time of peak values ​​in the direction of the dominant trend.

[0062] The differential duration calculation proposed in this invention quantifies the confidence level of operating condition changes by constructing a net time accumulation model based on the dominant trend. This method monitors the sign of the rate of change of the controlled variable in real time and maintains a time counter. When the sign of the rate of change is consistent with the direction of the dominant trend, the counter increments positively; when the sign is opposite, the counter decrements negatively. If the net time after the negative decrement remains within a certain range, it is considered an instantaneous disturbance; only when the accumulated amount of the negative decrement exceeds a certain proportion of the accumulated time in the dominant direction is it determined to be a trend reversal and the counter is reset. This is achieved through fault-tolerant processing of instantaneous negative disturbances (i.e., in...). (Retreats within the proportional range do not trigger reversals) effectively filter out high-frequency disturbances in the time dimension, thereby accurately extracting continuous trend characteristics that reflect the evolution of real working conditions and avoiding trend misjudgments caused by high-frequency fluctuations.

[0063] In the specific implementation of step 4, the system is set to be in a monitoring lockout state by default. ), only when At that time, the NOx conventional adjustment criterion was used. Priority criterion for ammonia escape To determine when to unlock.

[0064] First, check if the flue gas denitrification system is currently in a locked state. If it is in a locked state ( If the data is in a non-locked state, the process returns directly to step 1 to re-collect data without performing any adjustments; If so, then the tiered arbitration logic will be entered:

[0065] The first level of arbitration is based on the ammonia escape priority criterion. It uses the smoothed ammonia escape observations from step 2 as the basis to determine whether the ammonia escape priority criterion is met. The criterion expression is:

[0066] ;

[0067] In the formula, This indicates the priority criterion for ammonia escape; express Smoothed ammonia escape observations at specific times; Indicates the upper limit of ammonia escape concentration; This indicates the target value for ammonia escape. express The duration of the rise in ammonia escape at any given moment; The threshold for determining the duration of ammonia escape; express The rate of change in ammonia slip at any given time. When this criterion is met, subsequent routine nitrogen oxide regulation criteria are ignored, and the regulation command is triggered directly, prioritizing equipment safety and environmental compliance.

[0068] The second level of arbitration involves determining the routine adjustment criterion for nitrogen oxides. This criterion is based on the duration of the sliding integral and differential in step 3 to determine whether the routine adjustment criterion for nitrogen oxides is met. The criterion expression is:

[0069] ;

[0070] In the formula, This indicates the criteria for routine adjustment of nitrogen oxides; express Sliding integral at any time; The threshold representing the sliding integral; A threshold representing the duration of the derivative; express The net duration of nitrogen oxide emissions at any given time. The normal adjustment criterion is satisfied only when the absolute values ​​of the sliding integral and derivative durations simultaneously exceed the corresponding thresholds, triggering an adjustment command to ensure that the adjustment action is only executed when a substantial drift in the operating condition occurs.

[0071] If neither of the above two levels of arbitration criteria is met, the current operating condition is determined to be stable or fluctuating as an invalid disturbance, and the process returns to step 1 to collect data again.

[0072] This step employs high-priority control of ammonia slip to avoid secondary pollution and equipment blockage risks caused by excessive ammonia injection. This ammonia slip-priority interruption mechanism establishes a high-priority safety channel independent of conventional NOx control logic. The flue gas denitrification system monitors ammonia slip concentration and its derivative duration in real time. When the ammonia slip concentration exceeds the safety upper limit threshold, or when ammonia slip shows a continuous upward trend and the current value deviates from the target value, the flue gas denitrification system immediately activates an interruption signal. This signal directly bypasses the conventional criteria for sliding integral and derivative duration, forcing the system into a regulation state and outputting an instruction to reduce the reductant injection amount, thereby prioritizing equipment safety and preventing catalyst blockage under any operating condition. This step calculates the sliding integral value and derivative duration of NOx concentration in real time and in parallel. The system only generates a regulation instruction when the absolute value of the sliding integral exceeds a preset threshold, indicating that recent deviations have accumulated, and simultaneously, the absolute value of the derivative duration exceeds a preset threshold, indicating that NOx changes exhibit monotonicity and trend stability. This mechanism completely changes the conventional PID control mode based on instantaneous values ​​and solves the problem of frequent valve operation caused by large system lag and strong disturbances.

[0073] In the specific implementation of step 5, an improved PID algorithm with an ammonia escape constraint term is used to calculate the opening increment of the ammonia or urea injection valve. The calculation expression is as follows:

[0074] ;

[0075] In the formula, This indicates the increment in the opening of the ammonia or urea injection valve; This represents the scaling factor of the PIDA algorithm; Represents the integral coefficients of the PIDA algorithm; These represent the differential coefficients of the PIDA algorithm; express Instantaneous deviation at a given moment; express The sliding integral over time is used to reflect the recent cumulative deviation; express The instantaneous derivative of the observation is smoothed at each moment to reflect the steepness of the current trend of change; Indicates the characteristic function, when the ammonia escape priority criterion is applied. The value is 1 if the condition is met, and 0 otherwise. This indicates ammonia escape penalty; This indicates the priority criterion for ammonia escape; This indicates the ammonia escape penalty weight, which is used to suppress valve opening in reverse when ammonia escape exceeds the limit; express Smoothed ammonia escape observations at specific times; This indicates the target value for ammonia slip. It's worth noting that... , , These three coefficients are determined based on the dynamic characteristics of the denitrification system.

[0076] When the regulation command is issued by the ammonia escape logic When triggered, a penalty term is applied during the calculation, significantly reducing the valve opening. This occurs during valve regulation. Afterwards, the flue gas denitrification system immediately enters the forced cooling lockout state (set). ), and continue to lock the time. ,in, express The valve opening at any given moment; express The valve opening at any given moment; The forced cooling duration, preset according to the system's hysteresis characteristics, is used to provide sufficient equilibrium time for the denitrification chemical reaction, avoiding repeated adjustments and overshoot due to the lack of apparent regulatory effect. During the lockout period, except for emergency adjustments triggered by the ammonia escape priority criterion, the flue gas denitrification system blocks all adjustment requests, waiting for the chemical reaction to reach a new equilibrium before releasing the lockout state (setting...). Then, return to step 1 to re-enter the next control cycle. This forced cooling lock-in mechanism is specifically designed for the large hysteresis characteristics of the denitrification reaction, giving the system sufficient reaction time to prevent repeated adjustments and overshoots caused by the adjustment effect not yet being reflected at the measurement end.

[0077] Furthermore, the system includes segmented limiting steps for valve positions: the flue gas denitrification system dynamically adjusts the allowable valve opening range (minimum and maximum positions) based on different NOx concentration ranges. For example, in low NOx concentration ranges, the system automatically limits the maximum valve opening to prevent excessive ammonia injection; in extremely high NOx concentration ranges, the system raises the minimum valve opening limit to ensure basic denitrification efficiency. This segmented limiting strategy constrains the controller output within a reasonable range, further improving the system's safety and robustness.

[0078] This step employs an improved PID algorithm incorporating an ammonia slip constraint term. Based on the conventional three-term PID control, a fourth dimension is introduced: the ammonia slip constraint term (term A). The weighting coefficient of the ammonia slip constraint term is set to negative and it only participates in the calculation when the ammonia slip logic is triggered. The final opening increment is a linear superposition of the proportional, integral, derivative, and ammonia slip terms. This algorithm enables the controller to dynamically suppress ammonia slip through a negative feedback mechanism while pursuing denitrification efficiency, achieving multi-objective coordinated control.

[0079] It should be understood that, although this embodiment Figure 1 The steps are shown sequentially as indicated by the arrows, but they are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order in which these steps are performed; they can be executed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0080] Example 2

[0081] Based on the flue gas denitrification control method based on the sliding integral and derivative duration control in Example 1, this embodiment discloses a flue gas denitrification control device based on the sliding integral and derivative duration control, such as... Figure 2 As shown, the flue gas denitrification control device based on sliding integral and derivative duration start-up control includes: a data acquisition module 701, a data preprocessing module 702, a control index calculation module 703, a regulation trigger arbitration module 704, and a regulation execution and interlocking module 705, wherein:

[0082] The data acquisition module 701 is used to acquire raw concentration data in real time.

[0083] The data preprocessing module 702 is used to perform adaptive preprocessing on the raw concentration data to obtain smoothed observations, which include smoothed observations of nitrogen oxides and smoothed observations of ammonia escape.

[0084] The control index calculation module 703 is used to calculate the sliding integral by the cumulative deviation between the smoothed observation value of nitrogen oxides and the set target value within a preset time window; and to calculate the differential duration by the net cumulative time of the smoothed observation value of nitrogen oxides changing along the dominant trend direction.

[0085] The adjustment trigger arbitration module 704 is used to verify whether the flue gas denitrification system is in a locked state. If not, it uses the ammonia slip smooth observation value as a basis to determine whether the ammonia slip priority criterion is met. If it is met, an adjustment command is triggered. If it is not met, it uses the sliding integral and derivative duration as a basis to determine whether the nitrogen oxide conventional adjustment criterion is met. If it is met, an adjustment command is triggered. If neither is met or the flue gas denitrification system is in a locked state, it returns to the data acquisition module 701.

[0086] The regulation execution and interlocking module 705 is used to calculate the opening increment of the ammonia injection or urea injection valve using an improved PID algorithm with an ammonia escape constraint term when a regulation command is triggered; after the valve opening is adjusted according to the opening increment, the flue gas denitrification system is activated and maintained for a preset time, and then the data is returned to the data acquisition module 701.

[0087] In this embodiment, the specific working process and working principle of the data acquisition module 701, data preprocessing module 702, control index calculation module 703, adjustment trigger arbitration module 704, and adjustment execution and locking module 705 are the same as those in Embodiment 1, and therefore will not be described again in this embodiment. Each unit module can be implemented entirely or partially through software, hardware, or a combination thereof. Each unit module can be embedded in the processor of the computer device in hardware form or independent of it, or it can be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above unit modules.

[0088] Example 3

[0089] like Figure 3 The diagram illustrates a terminal device disclosed in this embodiment, comprising a transmitter, a receiver, a memory, and a processor. The transmitter transmits instructions and data, the receiver receives instructions and data, the memory stores computer-executed instructions, and the processor executes the computer-executed instructions stored in the memory to implement the method described in Embodiment 1 above.

[0090] It is important to note that the aforementioned memory can be either standalone or integrated with the processor. When the memory is set up independently, the terminal device also includes a bus for connecting the memory and the processor.

[0091] Example 4

[0092] This embodiment discloses a computer-readable storage medium storing computer-executable instructions. When a processor executes the computer-executable instructions, it implements the method in Embodiment 1 above.

[0093] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0094] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A flue gas denitrification control method based on sliding integral and derivative duration start-up control, characterized in that, The method includes: Step 1: Acquire raw concentration data in real time; Step 2: Perform adaptive preprocessing on the original concentration data to obtain smoothed observations, which include smoothed observations of nitrogen oxides and smoothed observations of ammonia escape. Step 3: Calculate the sliding integral based on the cumulative deviation between the smoothed nitrogen oxide observation value and the set target value within a preset time window; calculate the differential duration based on the net cumulative time of the smoothed nitrogen oxide observation value changing along the dominant trend direction. Step 4: Verify whether the flue gas denitrification system is in a locked state. If not, determine whether the ammonia slip priority criterion is met based on the ammonia slip smoothing observation value in Step 2. If it is met, trigger the adjustment command. If it is not met, determine whether the nitrogen oxide conventional adjustment criterion is met based on the sliding integral and derivative duration in Step 3. If it is met, trigger the adjustment command. If neither is met or the flue gas denitrification system is in a locked state, return to Step 1. Step 5: When the adjustment command is triggered, the improved PID algorithm with ammonia escape constraint term is used to calculate the opening increment of the ammonia injection or urea injection valve; after the valve opening is adjusted according to the opening increment, the flue gas denitrification system is activated and maintained for a preset time, and then the process returns to step 1. In step 3, the differential duration is calculated using the net cumulative time of the change in the smoothed nitrogen oxide observations along the dominant trend direction, including: Real-time monitoring of the differential sign of smoothed observations of nitrogen oxides, and maintenance of the current dominant trend direction and the peak accumulation time in the current dominant trend direction; The transient duration is calculated based on the differential symbol and the dominant trend direction. By comparing the transient duration with the peak accumulation time, we can verify whether the trend reversal condition is met and obtain the reversal condition verification result. The differential duration is calculated based on the inversion condition verification result, the differential symbol, the transient duration, and the dominant trend direction.

2. The flue gas denitrification control method based on sliding integral and derivative duration control according to claim 1, characterized in that, Step 2 involves adaptive preprocessing of the original concentration data, including: Step 201: Preset the effective physical threshold range corresponding to the original concentration data; Step 202: If the original concentration data obtained in step 1 exceeds the corresponding valid physical threshold range, then the original concentration data is determined to be an outlier. Step 203: For the outliers, replace them with the sliding median within the previous preset time window to obtain the corrected data sequence; Step 204: Perform a moving average calculation on the corrected data sequence according to the preset window length to obtain smoothed observations.

3. The flue gas denitrification control method based on sliding integral and derivative duration control according to claim 1, characterized in that, In step 3, the sliding integral is calculated based on the cumulative deviation between the smoothed observed value of nitrogen oxides and the set target value within a preset time window. The calculation expression is as follows: ； In the formula, express Sliding integral at any time; The fixed time window length represents the sliding integral. Indicates the sampling time; express Smoothed observations at any given time; This indicates the target value for nitrogen oxides; This indicates the total number of sampling points included in the sliding time window; Indicates instantaneous deviation; Indicates the sampling period; This represents the distance index within the sliding integral window.

4. The flue gas denitrification control method based on sliding integral and differential duration control according to any one of claims 1 to 3, characterized in that, The transient duration is calculated based on the differential symbol and the dominant trend direction, and the expression is: ； In the formula, express The duration of the transient state at a given moment; express The net duration of nitrogen oxide emissions at any given time; Indicates the sampling period; express The differential sign of the smoothed observation of nitrogen oxides at time; express The dominant trend direction at any given moment.

5. The flue gas denitrification control method based on sliding integral and derivative duration start-up control according to claim 4, characterized in that, The transient duration and the peak accumulation time are used to verify whether the trend reversal condition is met. The expression is: ； In the formula, This indicates the result of the reverse condition check; express The cumulative time of peaks that dominate the trend direction at any given moment; This indicates the threshold for determining the trend reversal.

6. The flue gas denitrification control method based on sliding integral and derivative duration control according to claim 5, characterized in that, The differential duration is calculated based on the reversal condition verification result, the differential sign, the transient duration, and the dominant trend direction. The expression is: ； In the formula, express The dominant trend direction at any given moment; express The net duration of nitrogen oxide emissions at any given time; express The cumulative time of peak values ​​in the direction of the dominant trend.

7. The flue gas denitrification control method based on sliding integral and derivative duration start-up control according to claim 5 or 6, characterized in that, In step 4, the smoothed ammonia slip observations from step 2 are used as the basis to determine whether the ammonia slip priority criterion is met. The criterion expression is: ； In the formula, This indicates the priority criterion for ammonia escape; express Smoothed ammonia escape observations at specific times; Indicates the upper limit of ammonia escape concentration; This indicates the target value for ammonia slip. express The duration of the rise in ammonia escape at any given moment; The threshold for determining the duration of ammonia escape; express The rate of change of ammonia escape at any given time.

8. The flue gas denitrification control method based on sliding integral and derivative duration start-up control according to claim 5 or 6, characterized in that, In step 4, the duration of the sliding integral and derivative from step 3 is used as the basis to determine whether the routine adjustment criterion for nitrogen oxides is met. The criterion expression is: ； In the formula, This indicates the criteria for routine adjustment of nitrogen oxides; express Sliding integral at any time; The threshold representing the sliding integral; A threshold representing the duration of the derivative; express The net duration of nitrogen oxide emissions at any given time.

9. The flue gas denitrification control method based on sliding integral and derivative duration start-up control according to claim 5 or 6, characterized in that, In step 5, an improved PID algorithm with an ammonia escape constraint term is used to calculate the opening increment of the ammonia or urea injection valve. The calculation expression is as follows: ； In the formula, This indicates the increment in the opening of the ammonia or urea injection valve; This represents the scaling factor of the PIDA algorithm; Represents the integral coefficients of the PIDA algorithm; Represents the differential coefficients of the PIDA algorithm; express Instantaneous deviation at a given moment; express Sliding integral at any time; express The instantaneous derivative of the smoothed observation; Indicates characteristic functions; This indicates ammonia escape penalty; This indicates the priority criterion for ammonia escape; Indicates the weight of the ammonia escape penalty; express Smoothed ammonia escape observations at specific times; This indicates the target value for ammonia escape.

Images