Method for determining limit load rate of coal-fired unit based on temperature change rate risk ratio

Abstract

The application discloses a kind of based on temperature change rate risk ratio's coal-fired unit limit variable load rate determination method, first determine the variable load interval and variable load direction to be evaluated, set multiple candidate variable load rates, and obtain the operating parameter, structural parameter and material parameter of thick-walled header of boiler under each candidate variable load rate;Then according to thick-walled header structural parameter, material parameter and operating parameter, calculate the allowable temperature change rate at each time, calculate actual temperature change rate according to metal wall temperature time sequence;Temperature change rate risk ratio is constructed, and the maximum temperature change rate risk ratio under each candidate variable load rate is obtained;Finally, with the maximum temperature change rate risk ratio is not greater than preset safety threshold as criterion, candidate variable load rate meeting temperature change rate safety constraint is screened, and the maximum value among them is determined as limit variable load rate under corresponding variable load interval and variable load direction.The method can quantitatively identify the safe variable load rate boundary in the process of coal-fired unit load increase and decrease, provide basis for depth peak shaving, fast variable load operation and variable load control instruction setting.

Description

Technical Field

[0001] This invention relates to the technical field of flexible operation of coal-fired power generating units and safety evaluation of thick-walled pressure-bearing components of boilers. Specifically, it relates to a method for determining the ultimate load change rate of a unit based on the risk ratio of temperature change rate. This method is applicable to determining the ultimate load change rate of a coal-fired power generating unit under the safety constraint of the temperature change rate of the boiler's thick-walled header during load increase, load decrease, deep peak shaving, rapid load change, and wide load operation. Background Technology

[0002] Against the backdrop of large-scale grid connection of new energy sources and increasing peak-shaving demands in the power system, coal-fired power units are gradually transforming from traditional baseload power sources to peak-shaving support power sources, requiring frequent participation in deep peak shaving and rapid load change operations. Increasing the load change rate of coal-fired power units helps enhance the grid's regulation capacity and the capacity for new energy absorption. However, rapid changes in unit load cause dynamic fluctuations in boiler-side steam temperature, steam pressure, flow rate, and metal wall temperature, subjecting the thick-walled pressure-bearing components of the boiler to stronger thermal and mechanical stress coupling effects.

[0003] Thick-walled pressure-bearing components of boilers, such as the high-temperature superheater outlet header, reheater header, main steam header, and steam-water separator, are subjected to high-temperature and high-pressure environments for extended periods. Due to their large wall thickness and high thermal inertia, they are prone to wall temperature response lag and transient temperature differences during load increases, decreases, and start-ups / shutdowns. When the rate of change in metal wall temperature is too high, the thermal stress induced by the rate of temperature change may superimpose with the internal mechanical stress, causing local stresses to approach or exceed the allowable stress of the material, thereby increasing the risk of thermal fatigue, crack initiation, and lifespan loss. Therefore, increasing the rate of change of load in coal-fired units cannot be based solely on main steam temperature control, load response speed, or system regulation capacity; the safety constraints of the rate of change of temperature for thick-walled pressure-bearing components of the boiler must also be considered.

[0004] Existing methods for setting the variable load rate of coal-fired power units are mostly based on operating experience, control system adjustment capabilities, or main steam temperature deviations, and typically lack quantitative evaluation of the safety boundary for the temperature change rate of thick-walled headers. Some methods can calculate the thermal stress or allowable temperature change rate of thick-walled pressure-bearing components, but these methods mostly remain at the level of safety verification under a single operating condition or at a single time point, making them difficult to directly apply to safety screening among different candidate variable load rates. For the same load range, the metal wall temperature change process, steam pressure change process, and thermal stress response all differ under different variable load rates, making it difficult to determine the safety of the entire variable load process based solely on the allowable temperature change rate at a single point.

[0005] Furthermore, the temperature response characteristics during load increases and decreases are not entirely the same, and the rates of change of steam pressure, metal temperature, and wall temperature vary significantly across different load ranges. Therefore, the ultimate load change rate for coal-fired units needs to be determined separately based on the specific load range, the direction of load change, and the dynamic response process of the thick-walled header. Without an evaluation index that characterizes the margin between the actual temperature change rate and the allowable temperature change rate, it is difficult to determine whether a candidate load change rate carries a risk of exceeding the temperature change rate limit, and it is also difficult to determine the maximum feasible load change rate that meets safety constraints.

[0006] Therefore, it is necessary to propose a method for determining the ultimate load change rate of a unit based on the risk ratio of temperature change rate. This method involves obtaining the allowable temperature change rate of the boiler's thick-walled header, combining the metal wall temperature time series under different candidate load change rates, calculating the risk ratio between the actual temperature change rate and the allowable temperature change rate, and using the maximum risk ratio throughout the entire load change process as a safety criterion to screen candidate load change rates that meet the safety constraints of temperature change rate. This determines the ultimate load change rate for the corresponding load range and load change direction, providing a basis for deep peak shaving, rapid load change operation, and load change control command setting for coal-fired units. Summary of the Invention

[0007] To overcome the limitations of existing technologies where the load change rate of coal-fired power units relies primarily on operational experience or control system adjustment capabilities, and where it is difficult to quantitatively consider the safety constraints of the temperature change rate of thick-walled boiler headers, this invention aims to provide a method for determining the ultimate load change rate of coal-fired power units based on the temperature change rate risk ratio. This method evaluates the safety margin of the temperature change rate of thick-walled headers under different candidate load change rates by constructing a risk ratio between the actual temperature change rate and the allowable temperature change rate, and uses the maximum temperature change rate risk ratio as a screening criterion to determine the ultimate load change rate that meets the safety constraints.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate includes the following steps: S1: Determine the load variation range and load variation direction of the coal-fired power unit to be evaluated. The load variation range includes a low-load increase range, a low-load decrease range, or a wide-load change range; the load variation direction includes the load increase process and the load decrease process.

[0009] S2: Set multiple candidate variable load rates and obtain the operating parameters, structural parameters, and material parameters of the boiler thick-walled header under each candidate variable load rate. The operating parameters include steam pressure, steam temperature, metal wall temperature, and metal wall temperature time series; the structural parameters include the header's inner diameter, outer diameter, average diameter, and wall thickness; the material parameters include elastic modulus, Poisson's ratio, coefficient of linear expansion, thermal conductivity, density, specific heat capacity at constant pressure, thermal diffusivity, and allowable stress of the material.

[0010] S3: Based on the structural parameters, material parameters, and operating parameters of the boiler's thick-walled header, calculate the allowable temperature change rate of the thick-walled header at each moment under each candidate variable load rate. The allowable temperature change rate is determined based on the internal mechanical stress of the thick-walled header, the thermal stress induced by the temperature change rate, and the allowable stress of the material, or obtained by the method for determining the allowable temperature change rate of the boiler's thick-walled header, and is updated as the steam pressure, metal temperature, wall thickness, and material parameters change.

[0011] S4: Calculate the actual temperature change rate of the thick-walled header at each moment under each candidate variable load rate based on the time series of the boiler thick-walled header metal wall temperature. The actual temperature change rate is obtained from the temperature difference of the metal wall at adjacent moments.

[0012] S5: Calculate the temperature change rate risk ratio based on the actual temperature change rate and the allowable temperature change rate, and obtain the maximum temperature change rate risk ratio for each candidate load change rate throughout the entire load change process.

[0013] The candidate variable load rate set, the temperature change rate risk ratio, and the maximum temperature change rate risk ratio are as follows: In the formula, V For the set of candidate variable load rates, ν L,j For the first j One candidate variable load rate, n The number of candidate variable load rates; R j ( t i ) is the first j At time 1 candidate variable load rate t i The risk ratio of temperature change rate; v real,j ( t i () represents the actual rate of temperature change; v al,j ( t i () represents the allowable rate of temperature change; Rmax,j For the first j The risk ratio of the maximum temperature change rate during the entire load change process under each candidate load change rate.

[0014] S6: Using the maximum temperature change rate risk ratio not exceeding the preset safety threshold as a safety criterion, candidate variable load rates that meet the temperature change rate safety constraints are selected.

[0015] S7: Select the maximum value among the candidate variable load rates that meet the safety constraints of temperature change rate as the ultimate variable load rate under strain load range and variable load direction: In the formula, v L,lim For the ultimate variable load rate, R lim For preset safety thresholds; when R lim When =1, it means that the actual temperature change rate does not exceed the allowable temperature change rate.

[0016] Furthermore, when the risk ratio of the maximum temperature change rate corresponding to two adjacent candidate load change rates is located on both sides of a preset safety threshold, an interpolation method can be used to determine the ultimate load change rate: In the formula, v L,a and v L,b These represent two adjacent candidate variable load rates. and These are the risk ratios of the maximum temperature change rate corresponding to two adjacent candidate load change rates, and R max,a ≤ R lim , R max,b > R lim .

[0017] Furthermore, the above steps S1 to S7 are performed on the load increase process and the load decrease process respectively to obtain the load increase limit change rate and the load decrease limit change rate.

[0018] Furthermore, the actual temperature change rate is obtained by time series difference of the boiler thick-walled header metal wall temperature, which includes the measured wall temperature, the simulated wall temperature, or the wall temperature calculated based on the steam temperature and the heat transfer model.

[0019] Furthermore, the variable load range includes 30%THA to 50%THA, 50%THA to 75%THA, 75%THA to 100%THA, or other load ranges.

[0020] Furthermore, the boiler thick-walled header includes a high-temperature superheater outlet header, a low-temperature superheater outlet header, a reheater outlet header, a main steam header, an economizer outlet header, a steam-water separator, or other boiler thick-walled pressure-bearing components.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention combines the allowable temperature change rate of thick-walled headers with the actual temperature change rate to construct a temperature change rate risk ratio, which can quantitatively characterize the margin of actual wall temperature change relative to the safety boundary during variable load process.

[0022] (2) The present invention uses the maximum temperature change rate risk ratio in the entire load change process as the safety criterion, which can avoid the shortcomings of judging the safety of the load change rate based on a single moment or experience value.

[0023] (3) The present invention can determine the limit load change rate under different load ranges and different load change directions, and is applicable to scenarios such as load increase, load decrease, deep peak shaving and wide load operation.

[0024] (4) This invention can be implemented based on simulation data, historical operation data or online monitoring data, and can provide a basis for setting the variable load rate of coal-fired units, verifying operation safety and correcting variable load control commands. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for determining the ultimate load rate based on the risk ratio of temperature change rate according to the present invention.

[0026] Figure 2 This is a schematic diagram illustrating the determination of the ultimate load rate based on the risk ratio of the maximum temperature change rate according to the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] This invention provides a method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate. This method is applicable to determining the ultimate load change rate of a coal-fired power unit during load increases, load decreases, deep peak shaving, rapid load changes, and wide-load operations, under the safety constraint of the temperature change rate of the boiler's thick-walled header. The method uses the allowable temperature change rate of the thick-walled header as the safety boundary and the risk ratio of the actual temperature change rate to the allowable temperature change rate as the evaluation index. By comparing the maximum temperature change rate risk ratio under different candidate load change rates, the maximum feasible load change rate that satisfies the safety constraint is determined.

[0029] In one specific implementation, such as Figure 1 As shown, the first step is to determine the load variation range and direction of the coal-fired power unit to be evaluated. The load variation range can be 30%THA–50%THA, 50%THA–75%THA, 75%THA–100%THA, or other load ranges. The load variation direction can be a load increase process or a load decrease process. For the same load range, the load increase process and the load decrease process are evaluated separately to obtain the corresponding load increase limit rate and load decrease limit rate.

[0030] Subsequently, a set of candidate load rate variations is established. These candidate load rates can be determined based on coal-fired unit operating experience, dispatching requirements, control system capabilities, or simulation test plans. For example, multiple candidate load rates can be set. v L,1 , v L,2 … v L,n For each candidate variable load rate, dynamic simulation, historical data extraction, or field operation tests were conducted to obtain the operating parameters, structural parameters, and material parameters of the boiler thick-walled header under strained load processes. The operating parameters include steam pressure, steam temperature, metal wall temperature, and metal wall temperature time series; the structural parameters include the header's inner diameter, outer diameter, average diameter, and wall thickness; and the material parameters include elastic modulus, Poisson's ratio, coefficient of linear expansion, thermal conductivity, density, specific heat capacity at constant pressure, thermal diffusivity, and allowable stress of the material.

[0031] For the j For each candidate load change rate, the allowable temperature change rate of the thick-walled header is calculated moment-by-moment according to the time series throughout the entire load change process. The allowable temperature change rate is determined based on the current steam pressure, metal temperature, wall thickness, and material parameters of the boiler's thick-walled header. Specifically, the internal pressure mechanical stress and the temperature change rate-induced thermal stress can be calculated first, and then the allowable temperature change rate can be derived by using the constraint that the total stress does not exceed the allowable stress of the material; alternatively, existing methods for determining the allowable temperature change rate of boiler thick-walled headers can be used directly. Since the steam pressure and metal temperature change with time during the load change process, the allowable temperature change rate is also dynamically updated over time.

[0032] Simultaneously, the first [time series] was calculated based on the metal wall temperature time series. jThe actual temperature change rate at each time step under each candidate variable load rate. The actual temperature change rate can be obtained by the difference in metal wall temperature between adjacent time steps. When the time unit of the wall temperature data is seconds, the difference result can be converted to K / min. The metal wall temperature can be obtained from on-site wall temperature measurement points, output results of dynamic simulation models, or calculated from steam temperature, steam pressure, flow rate, and heat transfer models. For wall temperature data with fluctuations or measurement noise, smoothing can be performed before calculating the actual temperature change rate to reduce the impact of accidental measurement errors on the risk assessment results.

[0033] like Figure 2 As shown, after obtaining the actual temperature change rate and the allowable temperature change rate, the temperature change rate risk ratio is calculated. For the ... j At time 1 candidate variable load rate t i The temperature change rate risk ratio is the ratio of the absolute value of the actual temperature change rate to the absolute value of the allowable temperature change rate. This risk ratio is used to characterize the proportion of the actual wall temperature change rate to the allowable temperature change rate at the current moment. When the risk ratio is closer to 1, it indicates that the safety margin of the temperature change rate under the current operating condition is smaller; when the risk ratio is greater than the preset safety threshold, it indicates that there is a risk of exceeding the temperature change rate limit under the corresponding candidate variable load rate.

[0034] Furthermore, take the first j The maximum temperature change rate risk ratio of a candidate load change rate throughout the entire load change process is used as the temperature change rate safety evaluation index for that candidate load change rate. Since the rates of change of steam pressure, metal temperature, and wall temperature all change over time during the load change process, the maximum temperature change rate risk ratio can reflect the most unfavorable moment in the entire load change process, thus avoiding the inadequacy of judging safety based solely on a single steady-state condition or average temperature change rate.

[0035] Then, the maximum temperature change rate risk ratio corresponding to each candidate variable load rate is compared with a preset safety threshold. When the maximum temperature change rate risk ratio corresponding to a candidate variable load rate is not greater than the preset safety threshold, the candidate variable load rate is determined to meet the temperature change rate safety constraint; when the maximum temperature change rate risk ratio is greater than the preset safety threshold, the candidate variable load rate is determined to have a risk of exceeding the temperature change rate limit. The preset safety threshold can be 1, or a value less than 1 can be taken according to the engineering safety margin requirements.

[0036] After selecting candidate load change rates that meet the safety constraints of temperature change rate, the maximum value among them is determined as the ultimate load change rate under the strain load range and load change direction. For the load increase and load decrease processes, the above steps are performed respectively to obtain the ultimate load change rate for load increase and load decrease. Since the steam temperature, steam pressure, flow rate, and metal wall temperature responses differ during load increase and load decrease processes, the corresponding ultimate load change rates may be different.

[0037] In another specific implementation, when the interval between candidate variable load rates is large, and the maximum temperature change rate risk ratios corresponding to two adjacent candidate variable load rates are located on both sides of a preset safety threshold, an interpolation method can be used to determine a more precise ultimate variable load rate. Specifically, a lower candidate variable load rate that meets the safety threshold requirement and a higher candidate variable load rate that does not meet the safety threshold requirement are selected, and linear interpolation is performed based on their corresponding maximum temperature change rate risk ratios to obtain the ultimate variable load rate corresponding to the preset safety threshold. This method can reduce the impact of discrete values ​​of candidate variable load rates on the accuracy of determining the ultimate variable load rate.

[0038] In one embodiment, taking the outlet header of a high-temperature superheater in a coal-fired power unit as an example, the ultimate load change rate is determined for the load increase process from 30% THA to 50% THA. First, multiple candidate load increase rates are set, and the header steam pressure, steam temperature, metal wall temperature, and metal wall temperature time series are obtained for each candidate rate. Then, the allowable temperature change rate is calculated based on the header structural parameters, material parameters, and operating parameters at each time point, and the actual temperature change rate is calculated based on the metal wall temperature time series. Further, the temperature change rate risk ratio at each time point is calculated, and the maximum value during the entire load increase process is taken as the maximum temperature change rate risk ratio for that candidate load increase rate. If the maximum temperature change rate risk ratio corresponding to a certain candidate load increase rate is not greater than a preset safety threshold, then that candidate load increase rate meets the temperature change rate safety constraint. Finally, the maximum value among all candidate load increase rates that meet the safety constraint is selected as the ultimate load change rate for the 30% THA to 50% THA load increase process.

[0039] In another embodiment, the same calculation process is performed on the load reduction process from 50% THA to 30% THA to obtain the limit load change rate of the load reduction process. By comparing the limit load change rates of the load increase and decrease processes, a basis can be provided for setting load change control commands for coal-fired units in different directions. When the risk ratio of the maximum temperature change rate corresponding to a certain candidate load change rate is close to the preset safety threshold, the load change rate can be appropriately reduced or the safety margin can be increased in actual operation to avoid exceeding the limit of the temperature change rate of the thick-walled header.

[0040] The method described in this invention is applicable not only to high-temperature superheater outlet headers, but also to low-temperature superheater outlet headers, reheater outlet headers, main steam headers, economizer outlet headers, steam-water separators, or other thick-walled pressure-bearing components of boilers. For different thick-walled pressure-bearing components, simply by replacing the corresponding structural parameters, material parameters, and operating boundary conditions, the same risk ratio evaluation process can be used to determine the corresponding ultimate load variation rate.

[0041] This invention can be used in conjunction with a dynamic simulation platform for coal-fired power units, a historical operation database, or an online monitoring system. In offline analysis, the time series of steam pressure, steam temperature, and wall temperature under different candidate load change rates can be obtained through dynamic simulation, thereby determining the safe load change rate boundary of the unit. In online applications, the temperature change rate risk ratio of the current load change process can be calculated based on real-time monitoring data, providing a basis for operational safety verification and load change control command setting.

[0042] The above embodiments illustrate the basic principles and application process of the present invention. Those skilled in the art can adjust the candidate variable load rate set, preset safety threshold, wall temperature data source, wall temperature smoothing method, allowable temperature change rate calculation method, and interpolation method without departing from the core idea of ​​the present invention; all such adjustments should fall within the protection scope of the present invention.

Claims

1. A method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate, characterized in that, A method for determining the ultimate load change rate under thermal stress safety constraints of thick-walled boiler headers during variable load operation of coal-fired power units includes the following steps: S1: Determine the load variation range and load variation direction of the coal-fired power unit to be evaluated. The load variation range includes a low-load load increase range, a low-load load decrease range, or a wide-load load variation range. The load variation direction includes the load increase process and the load decrease process. S2: Set multiple candidate variable load rates and obtain the operating parameters, structural parameters and material parameters of the boiler thick-walled header under each candidate variable load rate. The operating parameters include steam pressure, steam temperature, metal wall temperature and metal wall temperature time series. The structural parameters include header inner diameter, outer diameter, average diameter and wall thickness. The material parameters include elastic modulus, Poisson's ratio, coefficient of linear expansion, thermal conductivity, density, specific heat capacity at constant pressure, thermal diffusivity and allowable stress of the material. S3: Based on the structural parameters, material parameters and operating parameters of the boiler thick-walled header, calculate the allowable temperature change rate of the thick-walled header at each moment under each candidate variable load rate; S4: Calculate the actual temperature change rate of the thick-walled header at each moment under each candidate variable load rate based on the time series of the metal wall temperature of the thick-walled header in the boiler. S5: Calculate the temperature change rate risk ratio based on the actual temperature change rate and the allowable temperature change rate, and obtain the maximum temperature change rate risk ratio under each candidate variable load rate. S6: Using the maximum temperature change rate risk ratio not exceeding the preset safety threshold as a safety criterion, candidate variable load rates that meet the temperature change rate safety constraints are selected. S7: Select the maximum value among the candidate variable load rates that meet the safety constraints of temperature change rate as the ultimate variable load rate under strain load range and variable load direction.

2. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, The candidate variable load rate set in step S2 and the temperature change rate risk ratio and maximum temperature change rate risk ratio in step S5 are as follows: In the formula, V For the set of candidate variable load rates, ν L,j For the first j One candidate variable load rate, n The number of candidate variable load rates; R j ( t i ) is the first j At time 1 candidate variable load rate t i The risk ratio of temperature change rate; v real,j ( t i () represents the actual rate of temperature change; v al,j ( t i () represents the allowable rate of temperature change; R max,j For the first j The risk ratio of the maximum temperature change rate during the entire load change process under each candidate load change rate.

3. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, In step S7, the ultimate variable load rate is determined by the following formula: In the formula, v L,lim For the ultimate variable load rate, ν L,j For the first j One candidate variable load rate, R max,j For the first j The risk ratio of the maximum temperature change rate during the entire load change process under each candidate load change rate. R lim Preset safety threshold; when R lim When =1, it means that the actual temperature change rate does not exceed the allowable temperature change rate.

4. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 3, characterized in that, When the risk ratio of the maximum temperature change rate corresponding to two adjacent candidate load change rates is located on both sides of a preset safety threshold, the ultimate load change rate is determined by interpolation: In the formula, v L,a and v L,b These represent two adjacent candidate variable load rates. and These are the risk ratios of the maximum temperature change rate corresponding to two adjacent candidate load change rates, and R max,a ≤ R lim , R max,b > R lim .

5. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, In step S3, the allowable temperature change rate is determined based on the internal mechanical stress of the boiler thick-walled header, the thermal stress induced by the temperature change rate, and the allowable stress of the material, and is updated as the steam pressure, metal temperature, wall thickness, and material parameters change.

6. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, In step S4, the actual temperature change rate is obtained by the time series difference of the boiler thick-walled header metal wall temperature, which includes the measured wall temperature, the simulated wall temperature, or the wall temperature calculated based on the steam temperature and the heat transfer model.

7. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, Steps S1 to S7 are executed for the load increase process and the load decrease process respectively to obtain the load increase limit change rate and the load decrease limit change rate.

8. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, The variable load ranges include 30%THA to 50%THA, 50%THA to 75%THA, 75%THA to 100%THA, and a wide load range of 30%THA to 100%THA.

9. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, The boiler thick-walled header includes a high-temperature superheater outlet header, a low-temperature superheater outlet header, a reheater outlet header, a main steam header, an economizer outlet header, a steam-water separator, or a boiler thick-walled pressure-bearing component.

10. The method for determining the ultimate load change rate of a coal-fired power unit based on the risk ratio of temperature change rate according to claim 1, characterized in that, The method is used to determine the extreme load change rate during deep peak shaving, rapid load increase, rapid load decrease, start-up and shutdown processes, or wide load operation of coal-fired power units, and is also used for load change rate setting, operation safety verification, or control command correction.

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