A real-time control method and system applied to circulating fluidized bed boiler combustion

Abstract

The application discloses a kind of real-time control method and system applied to circulating fluidized bed boiler combustion, it is related to circulating fluidized bed technical field, comprising: by arranging multiple temperature monitoring points in bed and installing thermocouple device, realize real-time monitoring and recording to bed temperature;Identify and analyze multiple indexes that influence bed temperature, utilize control variable method and least square method, respectively, fit out the influence function of each index increase and decrease to bed temperature and stabilization time;System real-time monitoring each point temperature change, compared with preset normal temperature range, for abnormal monitoring point, flexible single monitoring point or multiple monitoring point adjustment strategy is adopted;Single monitoring point strategy is determined by screening influence function Optimal adjustment scheme;Multiple monitoring point strategy focuses on finding common index and adjustment mode, combined with single point strategy to realize comprehensive optimization;Through intelligent decision-making to circulating fluidized bed temperature adjustment process, the precision, real-time control of circulating fluidized bed boiler combustion is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circulating fluidized bed, in particular to a real-time control method and system applied to the combustion of circulating fluidized bed boiler. BACKGROUND

[0002] As a kind of efficient and clean combustion technology, circulating fluidized bed boiler has been widely used in industrial production and energy utilization. Its unique combustion mode, i.e. the flow area formed by solid particles and fluid (usually gas), enables fuel to burn more fully, improving combustion efficiency and heat utilization rate; however, the combustion process of circulating fluidized bed boiler is complex and variable, affected by many factors, among which the control of bed temperature is the key to ensure the safe and stable operation of the boiler.

[0003] Bed temperature is an important parameter in the combustion process of circulating fluidized bed boiler, which directly affects the combustion efficiency of fuel, the thermal efficiency of boiler and the emission of pollutants; too high or too low bed temperature will lead to unstable combustion, decreased thermal efficiency and equipment damage, etc.; therefore, real-time monitoring and effective control of bed temperature is an important means to ensure the normal operation of circulating fluidized bed boiler.

[0004] There are many ways to adjust bed temperature, and traditional bed temperature control methods mostly only adjust bed temperature by adjusting coal supply, primary air volume and secondary air volume, ignoring other ways to adjust bed temperature; in addition, when bed temperature anomaly is detected, traditional bed temperature control methods mostly rely on manual experience and simple control logic to select bed temperature adjustment mode, which is difficult to adapt to various changes in boiler combustion process and difficult to accurately and quickly select the bed temperature adjustment mode that has the least impact on the combustion state of other positions from multiple bed temperature adjustment modes, which leads to low control precision of circulating fluidized bed. SUMMARY

[0005] (I) Technical problems solved

[0006] To solve the technical problems in the background art, the present application proposes a real-time control method and system applied to the combustion of circulating fluidized bed boiler, which considers the influence of multiple indicators such as coal supply, primary air volume, secondary air volume, fuel particle size, return material quantity and slag discharge quantity on bed temperature, and when bed temperature anomaly is detected, according to the number of abnormal monitoring points and temperature deviation, through priority determination strategy, calculation of comprehensive temperature influence index and comprehensive time influence index, the bed temperature adjustment mode that has the least impact on the combustion state of other positions is quickly and accurately selected from multiple adjustment modes; thus, the technical problems recorded in the background art are solved.

[0007] (II) Technical solutions

[0008] To achieve the above object, the present application is implemented by the following technical solutions:

[0009] A real-time control method applied to combustion of a circulating fluidized bed boiler, comprising:

[0010] A thermocouple device is placed at several temperature monitoring points in the circulating fluidized bed bed layer to monitor the bed temperature at each temperature monitoring point in real time when the circulating fluidized bed is running, and the obtained bed temperature data is preprocessed and recorded in a temperature fold line graph;

[0011] Several indexes affecting the bed temperature are obtained; based on the control variable method and the least square method, a bed temperature influence function for each index when increasing and decreasing is fitted for different temperature monitoring points; the stable time after each adjustment is recorded and accumulated, and a stable time function for each index when increasing and decreasing is fitted for different temperature monitoring points using the least square method;

[0012] The temperature changes of each temperature monitoring point of the circulating fluidized bed are monitored in real time and compared with the set normal temperature range; when an abnormal monitoring point is found, a single monitoring point or multiple monitoring point adjustment strategy is executed according to the number of abnormal monitoring points;

[0013] The single monitoring point adjustment strategy determines the adjustment mode and value by screening the bed temperature influence function, calculates a comprehensive temperature influence index and a comprehensive time influence index by a priority determination strategy, and comprehensively selects the best adjustment mode;

[0014] The multiple monitoring point adjustment strategy screens the common index and adjustment mode, judges whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment mode, and combines the single monitoring point adjustment strategy to comprehensively select the best adjustment mode.

[0015] Specifically, the height h of the dense phase zone in the circulating fluidized bed bed layer is obtained, and the dense phase zone and the height h are selected as the candidate layers of the temperature monitoring points; the four target points are randomly selected on the candidate layer at the height h as the temperature monitoring points of the candidate layer, and the following relationship is required between any one temperature monitoring point and the remaining three temperature monitoring points: among the remaining three temperature monitoring points, the distance between the selected temperature monitoring point and two temperature monitoring points is the same;

[0016] (1) the distance between the selected temperature monitoring point and two temperature monitoring points is the same;

[0017] (2) the connecting line between the selected temperature monitoring point and the temperature monitoring point other than the two temperature monitoring points in (1) passes through the center of the corresponding candidate layer;

[0018] The temperature monitoring points selected on the candidate layer at the height h are respectively translated upward by the height h and the height h; the temperature monitoring points selected on the candidate layer at the height h are respectively translated upward by the height h and the height h;​​ Height, respectively obtained Temperature monitoring points were selected at height h and on the candidate layers at height h.

[0019] Specifically, the several indicators affecting bed temperature include six indicators: coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume, and slag discharge volume, which are denoted as E1 to E6 in the above order.

[0020] The circulating fluidized bed was operated according to the standard values ​​of six indicators; when combustion stabilized within the circulating fluidized bed, one indicator E was selected from the six indicators to fit the bed temperature influence function and the stabilization time function. i The values ​​of the other five indicators remain unchanged; within the allowable range, the selected indicator E is gradually increased or decreased. i The values ​​are recorded, and when combustion stabilizes again within the circulating fluidized bed, the bed temperature at each temperature monitoring point is recorded, as well as the time from the adjustment of the index to the re-stabilization of combustion within the bed; the allowable range is the reasonable range of the index value without affecting the safe and stable operation of the boiler, determined based on historical operating experience.

[0021] Furthermore, based on multiple independent increases or decreases in the selected indicator E i The values ​​of the temperature and the corresponding bed temperature T at each temperature monitoring point after each adjustment are used to fit the bed temperature influence function using the least squares method, resulting in... and These represent the selected indicator E respectively. i The value e i The influence function of bed temperature at each temperature monitoring point when increasing or decreasing, where P represents the temperature monitoring point, and u and d represent the selected index E, respectively. i The value e i The increase and decrease These represent the selected indicator E respectively. i The slope of the temperature influence function at temperature monitoring point P when the temperature increases or decreases. These represent the selected indicator E respectively. i The intercept of the temperature influence function at temperature monitoring point P when the temperature increases or decreases.

[0022] Specifically, based on multiple independent increases or decreases of the selected indicator E i The value is recorded, and the time required for combustion in the bed to stabilize again after each adjustment is recorded. The stabilization times after each adjustment are summed to obtain the total stabilization time t after multiple adjustments.

[0023] The steady-state time function was fitted using the least squares method to obtain... and These represent the selected indicator E respectively. i The value e i The influence function of bed temperature at each temperature monitoring point when the temperature increases and decreases, where, These represent the selected indicator E respectively. i The slope of the steady-state time function at temperature monitoring point P when the temperature increases or decreases. These represent the selected indicator E respectively. i The intercept of the steady-state time function at temperature monitoring point P when the temperature increases or decreases.

[0024] Specifically, during the operation of the circulating fluidized bed, the temperature changes at each temperature monitoring point in the line graph are monitored in real time; the real-time monitored temperatures at each temperature monitoring point are compared with the corresponding normal temperature range T. 1 T 2 T 3 Real-time comparison is performed, where T 1 T 2 T 3 Indicating the dense phase region And the normal temperature range at height h;

[0025] If the temperature at any temperature monitoring point other than the abnormal monitoring point exceeds the corresponding normal temperature range, the temperature monitoring point is marked as an abnormal monitoring point, and the judgment strategy is executed.

[0026] The judgment strategy is used to determine the number of abnormal monitoring points n at this time. If n=1, the single monitoring point adjustment strategy is executed; otherwise, the multi-monitoring point adjustment strategy is executed.

[0027] Specifically, the single monitoring point adjustment strategy is as follows:

[0028] Further analysis is conducted to determine the relationship between the temperature at the abnormal monitoring point and the corresponding normal temperature range. If the temperature at the abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is higher than the normal range. All slopes are then filtered out. or The index E corresponding to the bed temperature influence function less than 0 i If the temperature at the abnormal monitoring point is lower than the lower limit of the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is below the normal range; filter out all slopes. or The index E corresponding to the bed temperature influence function greater than 0 i Prioritize the selected indicators.

[0029] Specifically, the priority determination strategy is used to select the optimal adjustment method, including:

[0030] The adjustment mode and adjustment value of the screened index are determined in sequence; after the adjustment mode and adjustment value are determined, the temperature change of all the remaining temperature monitoring points after adjustment according to the adjustment mode and adjustment value is calculated; and it is judged whether the adjusted temperature at all the remaining temperature monitoring points exceeds the corresponding normal temperature range, if the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, the adjustment mode is deleted; otherwise, the adjustment mode is recorded in the set of candidate adjustment modes.

[0031] Further, the priority determination strategy further comprises:

[0032] Based on the relationship between the adjusted temperature at each of the remaining temperature monitoring points and the corresponding normal temperature range, the comprehensive temperature influence index of each adjustment mode in the set of candidate adjustment modes is calculated; based on the size relationship between the adjusted stable time at each of the remaining temperature monitoring points and the adjusted stable time at the abnormal monitoring point, the comprehensive time influence index of each adjustment mode in the set of candidate adjustment modes is calculated;

[0033] The comprehensive temperature influence index and the comprehensive time influence index of each adjustment mode in the set of candidate adjustment modes are added, and all the adjustment modes are sorted in descending order according to the sum, and the adjustment mode ranked first is selected to adjust the bed temperature.

[0034] Specifically, the multi-monitoring-point adjustment strategy specifically comprises:

[0035] Based on the single-monitoring-point adjustment strategy, the index for adjusting the bed temperature at each abnormal monitoring point is screened according to the size relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, and the adjustment mode and adjustment value of the screened index are determined;

[0036] The common index and adjustment mode of the multiple abnormal monitoring points are screened, and the adjustment value of each abnormal monitoring point under the adjustment mode is calculated; it is judged whether the temperature at all the abnormal monitoring points can be adjusted to the corresponding normal temperature range when the adjustment is made according to the maximum adjustment value; if so, it is further judged whether the adjusted temperature at all the remaining temperature monitoring points exceeds the corresponding normal temperature range under the adjustment mode and adjustment value, if the adjusted temperature at all the remaining temperature monitoring points does not exceed the corresponding normal temperature range, the bed temperature at each abnormal monitoring point is adjusted according to the adjustment mode and adjustment value; if the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, the single-monitoring-point adjustment strategy is performed in sequence according to the size of the value of the abnormal monitoring point exceeding the corresponding normal temperature range, to select the best adjustment mode.

[0037] A real-time control system applied to circulating fluidized bed boiler combustion, comprising:

[0038] The data acquisition module places thermocouple devices at several temperature monitoring points within the circulating fluidized bed to monitor the bed temperature at each monitoring point in real time during the operation of the circulating fluidized bed. The acquired bed temperature data is preprocessed and recorded in a temperature line graph.

[0039] The index determination module obtains several indicators for adjusting bed temperature based on theoretical knowledge, specifically including six indicators: coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume, and slag discharge volume.

[0040] The function fitting module includes a bed temperature influence function fitting unit and a stabilization time function fitting unit. The bed temperature influence function fitting unit fits the bed temperature influence function at different temperature monitoring points when each index increases and decreases, based on the control variable method and the least squares method, respectively. The stabilization time function fitting unit records and accumulates the stabilization time after each adjustment, and uses the least squares method to fit the stabilization time function at different temperature monitoring points when each index increases and decreases.

[0041] The adjustment method determination module includes a single-monitoring-point adjustment unit and a multi-monitoring-point adjustment unit. The single-monitoring-point adjustment unit executes a single-monitoring-point adjustment strategy when the number of abnormal monitoring points is determined to be only one. It determines the adjustment method and value by filtering the bed temperature influence function, calculates the comprehensive temperature influence index and comprehensive time influence index through a priority determination strategy, and comprehensively selects the optimal adjustment method. The multi-monitoring-point adjustment unit, when the number of abnormal monitoring points is determined to be multiple, filters common indicators and adjustment methods to determine whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value of the common adjustment method. It then combines this with the single-monitoring-point adjustment strategy to comprehensively select the optimal adjustment method.

[0042] (III) Beneficial Effects

[0043] This invention provides a real-time control method and system for combustion in a circulating fluidized bed boiler, which has the following beneficial effects:

[0044] 1. By scientifically selecting temperature monitoring points, accurately placing thermocouple devices, strictly pre-processing bed temperature data, and drawing temperature line graphs in real time, comprehensive and accurate monitoring of the temperature in the dense phase zone of the circulating fluidized bed is achieved, providing strong data support for timely detection of combustion anomalies, optimization of the combustion process, and improvement of boiler operating efficiency;

[0045] 2、By systematically identifying a plurality of key indicators affecting bed temperature, and using the control variable method and the least squares method, the influence function of these indicators on the bed temperature of different temperature monitoring points when increasing and decreasing, and the corresponding stable time function are fitted respectively; this provides accurate mathematical model support for real-time adjustment of combustion parameters and optimization of the combustion process, helps to achieve rapid and stable control of bed temperature, and further improves the combustion efficiency and operating stability of the circulating fluidized bed boiler;

[0046] 3、The design can timely discover and handle bed temperature abnormalities by real-time monitoring of the temperature changes of each temperature monitoring point of the circulating fluidized bed and comparing with the set normal temperature range, effectively avoids the boiler operation problems caused by excessively high or low bed temperature; for abnormal monitoring points, the design proposes single monitoring point adjustment strategy and multi-monitoring point adjustment strategy, which can flexibly select adjustment mode and value according to different abnormal conditions, ensures rapid and accurate recovery of bed temperature to the normal range, and further improves the combustion efficiency of the boiler;

[0047] 4、In the development of the adjustment strategy, the bed temperature influence function, priority determination strategy, and comprehensive temperature influence index and comprehensive time influence index are fully considered; by screening the indicators corresponding to the bed temperature influence function and determining the adjustment mode and value, the design can accurately find the factor that has the greatest impact on the bed temperature and make targeted adjustment; by calculating the comprehensive temperature influence index and the comprehensive time influence index, the design can comprehensively evaluate the overall impact of different adjustment modes on the bed temperature, so as to select the best adjustment mode; such fine adjustment strategy not only improves the control accuracy of the boiler, but also enhances the adaptability of the boiler to different working conditions, ensuring stable operation of the boiler. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A step flow chart of a real-time control method applied to the combustion of a circulating fluidized bed boiler is provided for the present application;

[0049] Figure 2 An implementation flow chart of a real-time control system applied to the combustion of a circulating fluidized bed boiler is provided for the present application;

[0050] Figure 3 A structural schematic diagram of a real-time control system applied to the combustion of a circulating fluidized bed boiler is provided for the present application. DETAILED DESCRIPTION

[0051] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] refer to Figure 1 and Figure 2 This invention provides a real-time control method for combustion in a circulating fluidized bed boiler, comprising:

[0053] Step 1: Place thermocouple devices at several temperature monitoring points within the circulating fluidized bed to monitor the bed temperature at each monitoring point in real time during the operation of the circulating fluidized bed. After preprocessing the acquired bed temperature data, record it in a temperature line graph.

[0054] Step one includes the following steps:

[0055] Step 101: Select 12 temperature monitoring points within the circulating fluidized bed. The specific selection method is as follows: Obtain the height h of the dense phase region within the circulating fluidized bed, and then... And the candidate layer at height h as the temperature monitoring point; because the dense phase region in the circulating fluidized bed is cylindrical, the shape of each candidate layer is circular; in Four target points are randomly selected on the candidate layer at a certain height as temperature monitoring points of the candidate layer. The following relationship is required between any one temperature monitoring point and the other three temperature monitoring points: (1) there are two temperature monitoring points that are equidistant from the selected temperature monitoring point; (2) the line connecting the other two temperature monitoring points to the selected temperature monitoring point passes through the center of the corresponding candidate layer. The four selected temperature monitoring points are denoted as A1, B1, C1 and D1 respectively.

[0056] In Temperature monitoring points selected on the candidate layers at the specified heights were shifted upwards respectively. Height and Height, respectively obtained Temperature monitoring points selected at height h and on the candidate layers are denoted as A2, B2, C2, and D2, and A3, B3, C3, and D3, respectively. Temperature monitoring points with the same letter are arranged in a vertically shifted relationship, and the subscripts 1, 2, and 3 correspond to the dense phase region, respectively. Temperature monitoring point at height h;

[0057] A total of 12 temperature monitoring points were selected using the method described above;

[0058] In a circulating fluidized bed, the bed refers to the flow region formed by solid particles and fluid (usually gas). The solid particles are in a fluidized state under the action of the gas, mainly including two regions: a dense phase region and a dilute phase region. The dense phase region is located at the bottom of the bed, where the concentration of solid particles is high. It is the main site of combustion and chemical reaction, and also the region where heat release is more concentrated. Monitoring the temperature in this region can help detect and adjust abnormal situations in the combustion process in a timely manner.

[0059] Step 102: Place thermocouple devices at each selected temperature monitoring point to monitor the temperature changes at the corresponding locations in the dense phase region during the operation of the circulating fluidized bed;

[0060] The basic principle of a thermocouple is the thermoelectric effect, which means that when the temperature changes, the free electrons in a conductor or semiconductor are affected by heat energy, thus generating a potential difference. A thermocouple consists of two wires made of different materials, connected at one end to form the measuring end, and the other end is connected to a measuring instrument to form the reference end. When the temperature of the measuring end changes, a potential difference is generated due to the different thermoelectric properties of the two materials. This potential difference has a certain functional relationship with the temperature. By measuring this potential difference, the temperature value of the measuring end can be determined.

[0061] Step 103: Preprocess the real-time acquired bed temperature data, including data cleaning, data calibration, and data normalization. First, perform data cleaning to remove outliers or missing values ​​caused by thermocouple device malfunctions, data transmission errors, or external interference, ensuring the accuracy and completeness of the data. Second, perform data calibration by correcting the measured values ​​according to the thermocouple device calibration certificate to eliminate systematic errors and improve data accuracy. Finally, perform data normalization to convert the bed temperature data from each temperature monitoring point to a unified dimensional range, facilitating subsequent data analysis and comparison.

[0062] Step 104: Set up a temperature line graph. Each temperature monitoring point corresponds to a line graph. The horizontal axis of the line graph represents time, and the vertical axis represents temperature. Associate each line graph with the corresponding temperature monitoring point. From the start of the circulating fluidized bed operation, record the pre-treated bed temperature data in the temperature line graph in real time until the end of this operation.

[0063] The temperature line graph allows for a direct observation of the temperature change trends at various monitoring points in the dense phase zone during the operation of the circulating fluidized bed, as well as the temperature differences between different monitoring points.

[0064] Combining the content of steps 101 to 104:

[0065] By scientifically selecting temperature monitoring points, precisely placing thermocouple devices, rigorously preprocessing bed temperature data, and drawing real-time temperature line graphs, comprehensive and accurate monitoring of the temperature in the dense phase zone of the circulating fluidized bed was achieved, providing strong data support for timely detection of combustion anomalies, optimization of the combustion process, and improvement of boiler operating efficiency.

[0066] Step 2: Obtain several indicators affecting bed temperature; use the control variable method and the least squares method to fit the influence function of each indicator on bed temperature at different temperature monitoring points when it increases and decreases; record and accumulate the stabilization time after each adjustment, and use the least squares method to fit the stabilization time function of each indicator at different temperature monitoring points when it increases and decreases.

[0067] Step two includes the following steps:

[0068] Step 201: Based on theoretical knowledge, obtain several indicators for adjusting bed temperature, including coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume, and slag discharge volume, totaling 6 indicators; and record them as E1 to E6 in the above order.

[0069] The coal feed rate refers to the amount of fuel fed into the furnace per unit time. The amount of coal feed directly determines the amount of heat released during combustion in the dense phase zone. An increase in the coal feed rate increases the heat released during combustion, and the bed temperature will rise; conversely, a decrease in the coal feed rate will cause the bed temperature to fall. The effect of the coal feed rate on the bed temperature has a lag, because it takes a certain amount of time for the fuel particles to burn completely and release heat after they are added.

[0070] Primary air volume refers to the air volume delivered by the primary air fan to the air distribution plate at the bottom of the furnace. In circulating fluidized bed boilers, it has two main functions: first, as fluidizing air to maintain the natural fluidization state of the bed material; and second, as a source of oxygen required for combustion. Adjusting the primary air volume will simultaneously affect the fluidization state of the dense phase zone and the combustion efficiency. Increasing the air volume can provide more oxygen to support combustion, but it will also remove more heat, leading to a decrease in bed temperature. Conversely, decreasing the air volume may worsen the fluidization effect and affect the combustion efficiency, but the bed temperature will increase.

[0071] Secondary air volume refers to the air volume of the secondary air fan supplied to the upper combustion zone of the furnace. It is mainly used to enhance the disturbance and mixing in the upper part of the furnace, so that the fuel combustion is more complete and the furnace outlet temperature is reduced. After the secondary air volume is increased, the combustion and heat transfer in the upper part of the furnace are enhanced, which may remove more heat and cause the bed temperature in the dense phase zone to decrease. However, the increase in secondary air volume also helps to improve the combustion efficiency in the entire furnace, thereby stabilizing or increasing the bed temperature to a certain extent.

[0072] Fuel particle size refers to the size of fuel particles. When the particle size is too small, the coal will be blown to the dilute phase zone by primary air as soon as it enters the furnace, and will burn in the dilute phase zone or the horizontal flue heating surface without significantly increasing the bed temperature. When the particle size is too large, the operator often uses a larger operating air volume to maintain the fluidized state of the bed material, otherwise the bed material will be stratified, and the bed temperature will be locally or globally over-temperature coking, which will delay the combustion time and reduce the bed temperature;

[0073] The amount of returned material refers to the amount of material collected from the separator of the circulating fluidized bed and sent back to the furnace. These materials sent back to the furnace generally have a lower temperature than the materials in the furnace, thereby adjusting the bed temperature, that is, when the amount of returned material increases, the bed temperature in the dense phase zone will decrease, and when the amount of returned material decreases, the bed temperature in the dense phase zone will increase.

[0074] The amount of slag discharged refers to the amount of ash and slag discharged from the bottom of the furnace per unit time. The amount of slag discharged directly affects the bed thickness and the amount of bed material, and thus affects the bed temperature. If the amount of slag discharged is too large, the bed thickness will decrease, the combustion will be complete, and thus the bed temperature will rise. Conversely, if the amount of slag discharged is too small, the bed thickness will increase, the combustion will be incomplete, and thus the bed temperature will decrease.

[0075] In step 202, based on theoretical knowledge and expert experience, the standard values of the above six indicators are obtained, that is, the standard values of each indicator that can ensure the combustion efficiency in the bed during the normal operation of the circulating fluidized bed boiler. The fitting of the bed temperature influence function at each temperature monitoring point for each indicator is performed in turn, specifically as follows:

[0076] The circulating fluidized bed is operated according to the standard values of the six indicators. When the combustion in the bed of the circulating fluidized bed is stable (that is, the bed temperature at each temperature monitoring point fluctuates within a set range and does not have a large abnormal rise or fall within a period of time), one indicator E i is selected from the six indicators to fit the bed temperature influence function and the stable time function, and the values of the remaining five indicators remain unchanged. The value of the selected indicator E i is gradually increased or decreased within a permissible range, and when the combustion in the bed of the circulating fluidized bed is stable again, the bed temperature at each temperature monitoring point and the time from the adjustment of the indicator to the stable combustion in the bed are recorded. The permissible range is a reasonable interval in which the indicator can be changed without affecting the safe and stable operation of the boiler, which is determined based on historical operation experience (the maximum and minimum values of the indicator when a temperature anomaly occurs and the cause is determined to be the indicator);

[0077] Based on multiple independent increases or decreases in the value of the selected indicator E i and the corresponding bed temperature values T at each temperature monitoring point after each adjustment, a linear function, that is, the fitting of the bed temperature influence function, is performed using the least squares method, to obtain and respectively represent the selected index E i i respectively represent the bed temperature influence function at each temperature monitoring point when the value e i of the selected index E i increases and decreases, respectively, respectively represent the selected index E i increases and decreases, respectively, respectively represent the slope of the temperature influence function at the temperature monitoring point P when the selected index E i increases and decreases, respectively;

[0078] wherein the least squares fitting function is a mathematical optimization method that finds the best fitting parameters by minimizing the sum of squared residuals between the data points and the fitting function, thereby obtaining a function that can most accurately describe the trend of the data;

[0079] After fitting all the indexes with functions, the bed temperature influence functions of all the indexes are obtained and

[0080] Step 203, based on multiple independent increases or decreases in the value of the selected index E i , record the time required for the combustion in the bed to stabilize again after each adjustment; accumulate the stabilization times after these single adjustments to obtain the total stabilization time t after multiple adjustments; for example: when the value of the selected index E i is increased for the first time, the time t1 required for the combustion at a certain temperature monitoring point to stabilize again after this adjustment is obtained, when the value of the selected index E i is increased for the second time, the time t2 required for the combustion at a certain temperature monitoring point to stabilize again after this adjustment is obtained; then directly adjust the value of the selected index E i to the total stabilization time t required for the value after the second increase, t = t1 + t2;

[0081] Use the least squares method to fit a linear function, i.e. the stabilization time function, to obtain and respectively represent the selected index E i when the value e i increases and decreases, respectively, the bed temperature influence function at each temperature monitoring point, wherein, respectively represent the selected index E i increases and decreases, respectively, the slope of the stabilization time function at the temperature monitoring point P, respectively represent the selected index E i increases and decreases, respectively, the intercept of the stabilization time function at the temperature monitoring point P;​

[0082] After function fitting of all indexes, the stable time function of all indexes is obtained With

[0083] In combination with the content in steps 201 to 203:

[0084] By systematically identifying a plurality of key indexes affecting the bed temperature, and using the control variable method and the least square method, the influence functions of these indexes on the bed temperature of different temperature monitoring points when increasing and decreasing, and the corresponding stable time functions are fitted respectively; this provides accurate mathematical model support for real-time adjustment of combustion parameters and optimization of the combustion process, and helps to realize rapid and stable control of the bed temperature, and further improve the combustion efficiency and operation stability of the circulating fluidized bed boiler.

[0085] Step three, real-time monitoring of the temperature changes of each temperature monitoring point of the circulating fluidized bed, and comparison with the set normal temperature range; when an abnormal monitoring point is found, a single monitoring point or multiple monitoring point adjustment strategy is executed according to the number of abnormal monitoring points; the single monitoring point adjustment strategy determines the adjustment mode and value by screening the bed temperature influence function, and calculates the comprehensive temperature influence index and comprehensive time influence index by the priority determination strategy to comprehensively select the best adjustment mode; the multiple monitoring point adjustment strategy screens the common indexes and adjustment modes, judges whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment mode, and combines the single monitoring point adjustment strategy to comprehensively select the best adjustment mode;

[0086] The step three includes the following steps:

[0087] Step 301, during the operation of the circulating fluidized bed, real-time monitoring of the temperature changes of each temperature monitoring point in the line graph, and setting the normal temperature range T 1 , T 2 , T 3 of each bed layer (i.e. the normal temperature range of the four temperature monitoring points at the height of 1.5H, 2H, 2.5H and 3H in the dense phase zone) according to theoretical knowledge and expert experience; Step 302, real-time comparison of the real-time monitored temperature of each temperature monitoring point with the corresponding normal temperature range, wherein the temperature of the four temperature monitoring points at the height of 1.5H, 2H, 2.5H and 3H in the dense phase zone is compared with the normal temperature range T 1 , and so on;

[0088] If the temperature of any temperature monitoring point other than the abnormal monitoring point is found to be out of the corresponding normal temperature range, mark the temperature monitoring point as an abnormal monitoring point, and execute the judgment strategy;

[0089]

[0090] ​​​The judgment strategy is as follows: determine the number of abnormal monitoring points n at this time. If n = 1, execute the single monitoring point adjustment strategy; otherwise, execute the multi-monitoring point adjustment strategy.

[0091] The single-monitoring-point adjustment strategy involves further determining the relationship between the temperature at the abnormal monitoring point and the corresponding normal temperature range. If the temperature at the abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is higher than the normal range. All slopes are then filtered out. or The index E corresponding to the bed temperature influence function less than 0 i These bed temperature influence functions will change with the index E i An increase or decrease in the slope causes a decrease in bed temperature; if the temperature at the abnormal monitoring point is lower than the lower limit of the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is below the normal range; all slopes are filtered out. or The index E corresponding to the bed temperature influence function greater than 0 i These bed temperature influence functions will change with the index E i The increase or decrease of the index causes the bed temperature to rise; a priority determination strategy is applied to the screened indicators.

[0092] The priority determination strategy involves sequentially determining the adjustment method (increase or decrease) and the adjustment value (increase or decrease value) for the selected indicators. For example, if decreasing indicator E1 can lower the bed temperature, then the adjustment value for indicator E1 needs to be determined. If the abnormal monitoring point is A1, then the adjustment value is determined based on the fitted bed temperature influence function: max The adjustment value e1 of indicator E1 can be obtained, that is, indicator E1 is reduced by e1;

[0093] After determining the adjustment method and adjustment value, calculate the temperature change at all other temperature monitoring points after adjustment according to the adjustment method and adjustment value; and determine whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, delete the adjustment method; otherwise, record the adjustment method in the set of candidate adjustment methods.

[0094] Based on the relationship between the adjusted temperature and the median of the corresponding normal temperature range at each of the remaining temperature monitoring points, the comprehensive temperature influence index of each adjustment method in the set of candidate adjustment methods is calculated. For example, for temperature monitoring point A2, the temperature after adjustment is: judge With the corresponding normal temperature range T 1 Median mid{T 1 The relationship between} and If then the adjustment mode has an exponential influence on the temperature of the temperature monitoring point A2 If then the adjustment mode has an exponential influence on the temperature of the temperature monitoring point A2 The exponential influence of the adjustment mode on the temperature of each of the remaining temperature monitoring points is accumulated to obtain the comprehensive temperature influence index of the adjustment mode; wherein max{T 1} represents the maximum value in the normal temperature range T 1 , i.e. the upper limit of the normal temperature range T 1 ; min{T 1} represents the minimum value in the normal temperature range T 1 , i.e. the lower limit of the normal temperature range T 1 ;

[0095] Based on the size relationship between the adjusted stable time at each of the remaining temperature monitoring points and the adjusted stable time at the abnormal monitoring point, the comprehensive time influence index of each adjustment mode in the set of candidate adjustment modes is calculated, such as: for the abnormal monitoring point A1, the adjusted stable time after adjustment by the adjustment mode is for the temperature monitoring point A2, the adjusted stable time is determine and , if then the adjustment mode has a time influence index on the temperature monitoring point A2 if then the adjustment mode has a time influence index on the temperature monitoring point A2 The time influence index of the adjustment mode on each of the remaining temperature monitoring points is accumulated to obtain the comprehensive time influence index of the adjustment mode.

[0096] The comprehensive temperature influence index and the comprehensive time influence index of each adjustment mode in the set of candidate adjustment modes are added, and all adjustment modes are sorted in descending order according to the added values, and the adjustment mode ranked first is selected to adjust the bed temperature;

[0097] Among them, the multi-monitoring-point adjustment strategy: based on the single-monitoring-point adjustment strategy, according to the size relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, the indicators for adjusting the bed temperature at each abnormal monitoring point are selected respectively, and the selected indicators are determined for adjustment mode and adjustment value.

[0098] A common indicator and adjustment method (with the same indicator and adjustment method) for multiple abnormal monitoring points are selected. The adjustment value for each abnormal monitoring point under this method is calculated. It is then determined whether the temperature at all abnormal monitoring points can be adjusted to the corresponding normal temperature range when the maximum adjustment value is applied. If so, it is further determined whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range under this method and value. If the adjusted temperature at all other temperature monitoring points does not exceed the corresponding normal temperature range, the bed temperature at each abnormal monitoring point is adjusted according to this method and value. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, a single-monitoring-point adjustment strategy is applied sequentially according to the magnitude of the deviation from the corresponding normal temperature range to select the optimal adjustment method.

[0099] Combining the content of steps 301 to 302:

[0100] This design monitors the temperature changes at various monitoring points in the circulating fluidized bed in real time and compares them with the set normal temperature range. This allows for timely detection and handling of abnormal bed temperatures, effectively preventing boiler operation problems caused by excessively high or low bed temperatures. For abnormal monitoring points, the design proposes single-monitoring-point adjustment strategies and multi-monitoring-point adjustment strategies. These two strategies can flexibly select adjustment methods and values ​​according to different abnormal situations, ensuring that the bed temperature quickly and accurately returns to the normal range, thereby improving the boiler's combustion efficiency.

[0101] In formulating the adjustment strategy, factors such as the bed temperature influence function, priority determination strategy, and comprehensive temperature influence index and comprehensive time influence index were fully considered. By screening the indicators corresponding to the bed temperature influence function and determining their adjustment methods and values, the design can accurately identify the factors with the greatest impact on the bed temperature and make targeted adjustments. By calculating the comprehensive temperature influence index and comprehensive time influence index, the design can comprehensively evaluate the overall impact of different adjustment methods on the bed temperature, thereby selecting the optimal adjustment method. This refined adjustment strategy not only improves the control accuracy of the boiler but also enhances the boiler's adaptability to different operating conditions, ensuring the stable operation of the boiler.

[0102] refer to Figure 3 The present invention also provides a real-time control system for combustion in a circulating fluidized bed boiler, comprising:

[0103] The data acquisition module places thermocouple devices at several temperature monitoring points within the circulating fluidized bed to monitor the bed temperature at each monitoring point in real time during the operation of the circulating fluidized bed. The acquired bed temperature data is preprocessed and recorded in a temperature line graph.

[0104] The index determination module obtains a plurality of indexes for adjusting the bed temperature based on theoretical knowledge, and the indexes specifically include six indexes of coal supply amount, primary air amount, secondary air amount, fuel particle size, return material amount, and slag discharge amount.

[0105] The function fitting module includes a bed temperature influence function fitting unit and a stable time function fitting unit; the bed temperature influence function fitting unit fits the bed temperature influence function of each index at increasing and decreasing times for different temperature monitoring points based on the control variable method and the least square method respectively; the stable time function fitting unit records and accumulates the stable time after each adjustment, and fits the stable time function of each index at increasing and decreasing times for different temperature monitoring points using the least square method;

[0106] The adjustment mode determination module includes a single monitoring point adjustment unit and a multiple monitoring point adjustment unit; the single monitoring point adjustment unit is used to execute a single monitoring point adjustment strategy when the number of abnormal monitoring points is determined to be one, to determine the adjustment mode and value by screening the bed temperature influence function, to calculate the comprehensive temperature influence index and the comprehensive time influence index by the priority determination strategy, and to comprehensively select the best adjustment mode; the multiple monitoring point adjustment unit is used to execute a multiple monitoring point adjustment strategy when the number of abnormal monitoring points is determined to be multiple, to determine the common adjustment mode and value by screening the common index and the adjustment mode, to determine whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment mode, and to comprehensively select the best adjustment mode in combination with the single monitoring point adjustment strategy.

[0107] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer storage medium or transmitted by a computer storage medium.

[0108] The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (for example, coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (for example, infrared, wireless, microwave, etc.) mode. The computer storage medium can be any available medium that the computer can access or a data storage device such as a server, data center, etc. containing one or more available media sets. The available media can be magnetic media (for example, floppy disk, hard disk, magnetic tape), optical media (for example, DVD), or semiconductor media (for example, solid state disk (SSD)) and the like.

[0109] The above description is only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for real-time control of combustion in a circulating fluidized bed boiler, characterized by: The application relates to a real-time control method for combustion of a circulating fluidized bed boiler. The method comprises the following steps: placing thermocouple devices at several temperature monitoring points in a circulating fluidized bed bed layer to monitor bed temperatures at each temperature monitoring point in real time when the circulating fluidized bed is running, recording the obtained bed temperature data in a temperature fold line graph after pretreatment, obtaining several indexes affecting the bed temperature, fitting bed temperature influence functions of different temperature monitoring points when each index is increased and decreased respectively based on a control variable method and a least square method, recording and accumulating stable time functions of different temperature monitoring points when each index is increased and decreased respectively, monitoring temperature changes of each temperature monitoring point of the circulating fluidized bed in real time and comparing the temperature changes with a set normal temperature range, executing a single monitoring point or multiple monitoring point adjustment strategy according to the number of abnormal monitoring points when an abnormal monitoring point is found, selecting a best adjustment mode through a single monitoring point adjustment strategy by screening bed temperature influence functions and then determining an adjustment mode and a value, and calculating a comprehensive temperature influence index and a comprehensive time influence index through a priority determination strategy. The method further comprises the following steps: screening common indexes and adjustment modes, judging whether all abnormal points can be adjusted to the normal temperature range under the maximum adjustment value in the common adjustment mode, and combining the single monitoring point adjustment strategy to comprehensively select the best adjustment mode.

2. The real-time control method for combustion of a circulating fluidized bed boiler according to claim 1, wherein: (1) the distance between two temperature monitoring points and the selected temperature monitoring point is the same; (2) a line connecting a temperature monitoring point other than the two temperature monitoring points in (1) and the selected temperature monitoring point passes through the center of the corresponding candidate layer; 3. The real-time control method for combustion of a circulating fluidized bed boiler according to claim 2, wherein:

4. The real-time control method for combustion of a circulating fluidized bed boiler according to claim 3, wherein: Obtain the height of the dense phase region within the circulating fluidized bed. Within the dense phase region , as well as The height is used as a candidate layer for temperature monitoring points; in Four target points are randomly selected on the candidate layer at a certain altitude as temperature monitoring points for that candidate layer. The following relationship must exist between any one temperature monitoring point and the other three temperature monitoring points: (The remaining three temperature monitoring points...) 5. The real-time control method for combustion of a circulating fluidized bed boiler according to claim 4, wherein:

6. The real-time control method for combustion of a circulating fluidized bed boiler according to claim 5, wherein: The temperature monitoring points selected on the alternative layer at the height of The temperature monitoring points selected on the alternative layer at the height of The height and The height, respectively, to obtain The temperature monitoring points selected on the alternative layer at the height of The temperature monitoring points selected on the alternative layer at the height of If the temperature of any temperature monitoring point other than the abnormal monitoring point is found to be out of the corresponding normal temperature range, the temperature monitoring point is marked as an abnormal monitoring point, and the judgment strategy is executed; The several indexes affecting the bed temperature include six indexes of coal supply amount, primary air amount, secondary air amount, fuel granularity, return material amount and slag discharge amount, and are sequentially recorded as to ; According to the standard value of the six indexes, the circulating fluidized bed is operated; when the combustion in the bed of the circulating fluidized bed is stable, one index is selected from the six indexes to fit the bed temperature influence function and the stable time function , the values of the remaining five indexes remain unchanged; the value of the selected index is gradually increased or decreased within an allowed range, and when the combustion in the bed of the circulating fluidized bed is stable again, the bed temperature at each temperature monitoring point is recorded, and the time from the adjustment index to the stable combustion in the bed is recorded again; wherein the allowed range is a reasonable interval of the index value under the premise of not affecting the safe and stable operation of the boiler, which is determined based on historical operation experience. ​ The single monitoring point adjustment strategy is as follows: Based on multiple independent increases or decreases of selected indicators The values, and the corresponding bed temperature values ​​at each temperature monitoring point after each adjustment. The bed temperature influence function was fitted using the least squares method to obtain... and , respectively representing the selected indicators numerical value The influence function of bed temperature at each temperature monitoring point when the temperature is increased or decreased, where, Indicates temperature monitoring point, and Each represents a selected indicator. numerical value The increase and decrease , Each represents a selected indicator. When increasing or decreasing, temperature monitoring points The slope of the function affecting bed temperature. , Each represents a selected indicator. When increasing or decreasing, temperature monitoring points The intercept of the function affecting bed temperature. The priority determination strategy is used to screen the best adjustment mode, and the priority determination strategy is as follows: Based on multiple independent increases or decreases in the value of a selected metric The time required for combustion to again stabilize within the bed after each adjustment is recorded. The stable time of these single adjustments is accumulated to obtain the total stable time of multiple adjustments ; The steady-state time function was fitted using the least squares method to obtain... and , respectively representing the selected indicators numerical value The settling-time function at each temperature monitoring point during both increasing and decreasing temperatures, where, , Each represents a selected indicator. When increasing or decreasing, temperature monitoring points The slope of the steady-state time function. , Each represents a selected indicator. When increasing or decreasing, temperature monitoring points The intercept of the steady-state time function. The indexes are adjusted in sequence, and after the adjustment mode and the adjustment value are determined, the temperature changes of all the remaining temperature monitoring points after adjustment are calculated; and it is judged whether the adjusted temperature of any temperature monitoring point is out of the corresponding normal temperature range, if yes, the adjustment mode is deleted; During the operation of the circulating fluidized bed, the temperature changes at each temperature monitoring point in the broken line graph are monitored in real time; the temperature at each temperature monitoring point monitored in real time is compared with the corresponding normal temperature range 、 、 in real time, wherein 、 、 the normal temperature range at the height of the dense phase zone 、 and ​ Otherwise, the adjustment mode is recorded in the candidate adjustment mode set. The judgment strategy is used to judge the number of abnormal monitoring points at this time , if , a single monitoring point adjustment strategy is executed; otherwise, a multiple monitoring point adjustment strategy is executed.

7. A method for real time control of combustion in a circulating fluidized bed boiler as claimed in claim 6, characterized in that ​ determining the size relationship between the temperature at the abnormal monitoring point and the corresponding normal temperature range, if the temperature at the abnormal monitoring point exceeds the upper limit of the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is higher than the normal range; screening out all the indexes corresponding to the bed temperature influence function or whose slope is less than 0 ; if the temperature at the abnormal monitoring point is lower than the lower limit in the corresponding normal temperature range, it indicates that the temperature at the abnormal monitoring point is lower than the normal range; screening out all the indexes corresponding to the bed temperature influence function or whose slope is greater than 0 ; performing priority determination strategy on the screened indexes.

8. A method for real time control of combustion in a circulating fluidized bed boiler as claimed in claim 7, characterized in that: ​ ​ ​ Based on the relationship between the adjusted temperature at each of the remaining temperature monitoring points and the median of the corresponding normal temperature range, the comprehensive temperature influence index of each adjustment method in the candidate adjustment method set is calculated; based on the relationship between the adjusted stabilization time at each of the remaining temperature monitoring points and the adjusted stabilization time at the abnormal monitoring points, the comprehensive time influence index of each adjustment method in the candidate adjustment method set is calculated. Add the comprehensive temperature influence index and comprehensive time influence index of each adjustment method in the pool of candidate adjustment methods, and sort all adjustment methods in descending order of the sum. Select the adjustment method ranked first to adjust the bed temperature.

9. A method for real time control of combustion in a circulating fluidized bed boiler as claimed in claim 8, characterized in that: The multi-monitoring point adjustment strategy is specifically as follows: Based on the single monitoring point adjustment strategy, according to the relationship between the temperature at each abnormal monitoring point and the corresponding normal temperature range, indicators for adjusting the bed temperature at each abnormal monitoring point are selected, and the adjustment method and adjustment value of the selected indicators are determined. The common indicators and adjustment methods of multiple abnormal monitoring points are screened out, and the adjustment value of each abnormal monitoring point is calculated under the adjustment method. It is then determined whether the temperature at all abnormal monitoring points can be adjusted to the corresponding normal temperature range when the adjustment is made according to the largest adjustment value. If possible, continue to determine whether the adjusted temperature at all other temperature monitoring points exceeds the corresponding normal temperature range under the adjustment method and adjustment value. If the adjusted temperature at all other temperature monitoring points does not exceed the corresponding normal temperature range, then adjust the bed temperature at each abnormal monitoring point according to the adjustment method and adjustment value. If the adjusted temperature at any temperature monitoring point exceeds the corresponding normal temperature range, then perform single monitoring point adjustment strategies sequentially according to the magnitude of the abnormal monitoring point's deviation from the corresponding normal temperature range to select the optimal adjustment method.

10. A real-time control system for use in circulating fluidized bed boiler combustion, characterized in that, include: The data acquisition module places thermocouple devices at several temperature monitoring points within the circulating fluidized bed to monitor the bed temperature at each monitoring point in real time during the operation of the circulating fluidized bed. The acquired bed temperature data is preprocessed and recorded in a temperature line graph. The index determination module obtains several indicators for adjusting bed temperature based on theoretical knowledge, specifically including six indicators: coal feed rate, primary air volume, secondary air volume, fuel particle size, return material volume, and slag discharge volume. The function fitting module includes a bed temperature influence function fitting unit and a stabilization time function fitting unit. The bed temperature influence function fitting unit fits the bed temperature influence function at different temperature monitoring points when each index increases and decreases, based on the control variable method and the least squares method, respectively. The stabilization time function fitting unit records and accumulates the stabilization time after each adjustment, and uses the least squares method to fit the stabilization time function at different temperature monitoring points when each index increases and decreases. The adjustment method determination module includes a single monitoring point adjustment unit and a multi-monitoring point adjustment unit; The single-monitoring-point adjustment unit is configured to execute a single-monitoring-point adjustment strategy when the number of abnormal monitoring points is determined to be one, to determine an adjustment mode and a value by screening a bed temperature influence function, to calculate a comprehensive temperature influence index and a comprehensive time influence index by using a priority determination strategy, and to comprehensively select an optimal adjustment mode. The multi-monitoring-point adjustment unit is configured to execute a multi-monitoring-point adjustment strategy when the number of abnormal monitoring points is determined to be multiple, to screen a common index and an adjustment mode, to determine whether all abnormal points can be adjusted to a normal temperature range under a maximum adjustment value in the common adjustment mode, and to comprehensively select an optimal adjustment mode in combination with the single-monitoring-point adjustment strategy.

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