Methods and systems for dynamic optimization control of water and coal coordination in deep peak shaving of supercritical units

Abstract

This invention discloses a dynamic optimization control method and system for deep peak-shaving water-coal coordination in supercritical power units, comprising: acquiring unit load and boiler main control commands; obtaining fuel commands and feedwater commands based on the boiler main control commands; determining the stage of unit load; performing differential correction on the feedwater commands based on the lag time and inertia order corresponding to the stage of unit load to obtain corrected feedwater commands; controlling coal feed through fuel commands; and controlling feedwater through the corrected feedwater commands. Based on the unit load, the lag time and inertia order are determined, and then the feedwater commands are differentially corrected based on the lag time and inertia order to obtain corrected feedwater commands. The fuel commands and corrected feedwater commands are used to control fuel and feedwater respectively, making the rate of water action in the boiler more matched with the rate of fuel action in the boiler, thereby avoiding large fluctuations in main steam pressure and temperature.

Description

Technical Field

[0001] This invention relates to the field of water-coal coordination control technology for deep peak shaving in supercritical units, and particularly to a dynamic optimization control method and system for water-coal coordination for deep peak shaving in supercritical units. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] The new power system is based on new energy sources, but the intermittent and fluctuating nature of new energy power generation means that the construction of the new power system cannot be separated from the support of coal-fired power units. During the energy structure transformation process, the "ballast" role of coal-fired power units will become increasingly important. It is necessary to strengthen the guarantee of coal-fired power as a safety net and actively promote the transformation of coal-fired power from a primary power source to a basic power source providing reliable capacity, peak shaving, frequency regulation, and other ancillary services. The minimum technical output of existing coal-fired power units is generally 50% of rated load, and flexibility upgrades are needed to reduce the minimum technical output to 30% of rated load.

[0004] Thermal power units, especially supercritical units, have lower regulation capabilities under deep peak-shaving conditions than under conventional conditions (above 50% rated load). Furthermore, compared to subcritical units, supercritical units have lower heat storage capacity and lower thermal inertia. Therefore, the regulation capabilities of supercritical units under deep peak-shaving conditions are inferior to those of subcritical units. The poor regulation capabilities of supercritical units under deep peak-shaving conditions are mainly manifested in the following aspects:

[0005] (1) Poor primary frequency regulation and AGC regulation capabilities. The primary frequency regulation qualification rate of supercritical units decreases under deep peak shaving conditions, and the response is often weak. Under deep peak shaving conditions, the AGC regulation performance index of supercritical units decreases.

[0006] (2) Under deep peak shaving conditions, the main steam temperature and pressure of supercritical units fluctuate greatly, which is not conducive to the safe and stable operation of the unit and may lead to unit tripping in severe cases.

[0007] The mismatch in response speed between coal and water is the main reason for the poor regulation capacity of supercritical units under deep peak-shaving conditions. Supercritical units respond very quickly to feedwater changes; the feedwater pumps activate immediately after a change in feedwater command, and the actual feedwater volume changes instantly. In contrast, after a change in fuel command, the feedwater in a supercritical unit must pass through the coal feeder, the coal mill, the primary air carrying pulverized coal into the furnace, the pulverized coal combustion, and the water-cooled wall heat transfer stage. Therefore, the response speed of coal is slower than that of water.

[0008] Under steady-state conditions, the mismatch in response speed between coal and water does not have an adverse effect. However, the volatility of new energy power generation, coupled with the impact of extreme weather, causes thermal power units to frequently participate in load regulation under both deep peak-shaving and normal operating conditions. For example, when the unit load increases, the feedwater flow increases, and the heat from the coal takes a period of time to be conducted to the water-cooled walls. This causes aggravated fluctuations in main steam temperature and pressure. Fluctuations in main steam temperature affect unit safety, while fluctuations in main steam pressure not only reduce the unit's economic efficiency but also affect the unit's primary frequency regulation and AGC (Automatic Generation Control) regulation.

[0009] Under deep peak shaving conditions, the various actuators of a supercritical unit are in the nonlinear adjustment zone. The nonlinear adjustment of the actuators amplifies the mismatch between the response speeds of coal and water, resulting in poor regulation capability of the supercritical unit under deep peak shaving conditions. The primary frequency regulation and AGC regulation performance of the unit do not meet the requirements, causing the unit to be subject to assessment or reducing the unit's ancillary service revenue. Summary of the Invention

[0010] To address the aforementioned problems, this invention proposes a dynamic optimization control method and system for deep peak-shaving water-coal coordination in supercritical units. Based on the unit load, the lag time and inertia order are determined. Then, the feedwater command is differentially corrected based on the lag time and inertia order to obtain the corrected feedwater command. The fuel command and the corrected feedwater command are used to control the fuel and feedwater respectively, making the rate of water action in the boiler more closely match the rate of fuel action in the boiler. This avoids large fluctuations in main steam pressure and temperature, thereby improving the unit's regulation capability.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] Firstly, a dynamic optimization control method for deep peak-shaving water-coal coordination in supercritical units is proposed, including:

[0013] Obtain unit load and boiler main control commands;

[0014] Fuel and water supply commands are obtained based on the boiler master control commands;

[0015] Determine the stage of unit load;

[0016] Based on the lag time and inertia order corresponding to the stage of unit load, the feedwater command is differentially corrected to obtain the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; extract the matching effective data segments of fuel change and feedwater change... The outlet temperature of the steam-water separator is extracted from each segment. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater variation is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel variation to obtain the optimal lag time and optimal inertia order. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle.

[0017] Coal supply is controlled via fuel commands;

[0018] The water supply is controlled by modifying the water supply command.

[0019] Furthermore, the main steam pressure, steam enthalpy at the steam-water separator outlet, and unit load are obtained;

[0020] The energy signal is determined by the main steam pressure;

[0021] The energy requirement is determined by the enthalpy of the steam at the outlet of the steam-water separator;

[0022] Calculate the difference between the energy signal and the energy demand, and the rate of change of this difference;

[0023] The difference between the energy signal and the energy demand, and the rate of change of the difference, are input into the PID controller, which outputs the energy command.

[0024] The boiler main control command is obtained by multiplying the unit load by a set coefficient and then adding it to the energy command.

[0025] Furthermore, the first-stage pressure of the steam turbine is obtained;

[0026] The energy signal is obtained by dividing the first-stage pressure of the steam turbine by the main steam pressure and then multiplying it by the main steam pressure setpoint.

[0027] or,

[0028] The energy requirement is obtained by adding the differential of the first-stage pressure of the steam turbine and the enthalpy of the steam at the separator outlet.

[0029] or,

[0030] Obtain the main steam flow rate;

[0031] The first-stage pressure of the steam turbine is determined based on the main steam flow rate and the corresponding function between the main steam flow rate and the first-stage pressure of the steam turbine.

[0032] or,

[0033] Obtain the outlet steam temperature and pressure of the steam-water separator, and determine the outlet steam enthalpy value based on the steam thermodynamic properties table and the outlet steam temperature and pressure of the steam-water separator.

[0034] Furthermore, based on the obtained boiler main control command and the corresponding function between the boiler main control command and the feedwater, the feedwater command is obtained;

[0035] or,

[0036] By designing the ratio of the calorific value of coal type to the calorific value of boiler coal, the corresponding function between boiler main control command and fuel command is modified. Based on the modified function and the obtained boiler main control command, the fuel command is obtained.

[0037] Furthermore, fuel control output values ​​are obtained through fuel commands; the coal feeder is then controlled based on these fuel control output values.

[0038] or,

[0039] The water supply control output value is obtained by modifying the water supply command; the water pump is controlled according to the water supply control output value.

[0040] or,

[0041] The actual fuel quantity is controlled by PID control using fuel commands to obtain the fuel control output value;

[0042] or,

[0043] The actual water supply is controlled by PID control using the corrected water supply command to obtain the water supply control output value.

[0044] Furthermore, the stage it is in is the first stage, the second stage, or the third stage;

[0045] or,

[0046] When the unit load is greater than or equal to 30% of the rated load and less than or equal to 40% of the rated load, the unit load is in the first stage.

[0047] or,

[0048] When the unit load is greater than or equal to 50% of the rated load, the unit load is in the second stage.

[0049] or,

[0050] When the unit load is greater than 40% of the rated load but less than 50% of the rated load, the unit load is in the third stage.

[0051] Furthermore, the operating data of the unit in the previous operating cycle is obtained, including the steam temperature at the outlet of the steam-water separator, fuel command, feedwater command and unit load;

[0052] Based on the stage of unit load in the previous operating cycle, the operating data of the previous operating cycle is divided into stages to obtain operating data for multiple stages.

[0053] For each stage of operation data, acquire all valid data segments of fuel changes and all valid data segments of feedwater changes;

[0054] Select the matching valid data segments for fuel change and feedwater change from all valid data segments for fuel change and feedwater change.

[0055] Furthermore, when the unit load deviation in the effective data segment of fuel change and the effective data segment of feedwater change are within the set deviation; the ratio of the feedwater command in the effective data segment of feedwater change to the fuel command in the effective data segment of fuel change is within the set deviation range from the design value of the water-coal ratio; and the direction of change of the feedwater command in the effective data segment of feedwater change is opposite to the direction of change of the fuel command in the effective data segment of fuel change, it indicates that the effective data segment of fuel change and the effective data segment of feedwater change are matched.

[0056] or,

[0057] If the water supply command remains unchanged but the fuel command changes, extract the valid data segment of the fuel change from the operating data.

[0058] or,

[0059] If the fuel command remains unchanged but the feedwater command changes, extract the valid data segment of the feedwater change from the operating data.

[0060] Secondly, a dynamic optimization control system for deep peak-shaving water-coal coordination in supercritical units is proposed, including:

[0061] The rapid boiler main control module is used to acquire unit load and boiler main control commands;

[0062] The instruction allocation module is used to obtain fuel instructions and feedwater instructions based on the boiler main control instructions;

[0063] The speed matching module is used to perform differential correction on the feedwater command based on the lag time and inertia order corresponding to the stage of unit load, thereby obtaining the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; and extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage. In the effective data segment of the feedwater variation, the outlet temperature of the steam-water separator is extracted. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater variation is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel variation to obtain the optimal lag time and optimal inertia order. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle.

[0064] A fuel controller is used to control the coal feed via fuel commands;

[0065] A water supply controller is used to control the water supply by means of a modified water supply command.

[0066] Thirdly, an electronic device is proposed, including a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When the computer instructions are executed by the processor, they complete the steps described in the method for deep peak shaving of supercritical units and coordinated dynamic optimization control of water and coal.

[0067] Fourthly, a computer-readable storage medium is proposed for storing computer instructions, which, when executed by a processor, complete the steps described in the method for deep peak shaving water-coal coordinated dynamic optimization control of supercritical units.

[0068] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0069] 1. This invention determines the corresponding lag time and inertia order based on the stage of unit load, and then performs differential correction on the feedwater command based on the lag time and inertia order to obtain the corrected feedwater command. The fuel command and the corrected feedwater command are used to control the fuel and feedwater respectively, so that the rate at which water acts in the boiler after feeding water and coal is more matched with the rate at which fuel acts in the boiler, thereby avoiding large fluctuations in main steam pressure and temperature, which is conducive to the safe and stable operation of the unit.

[0070] 2. When determining the boiler main control command, this invention takes into account the difference in calorific value between the daily coal used in the boiler and the designed coal type, and corrects the correspondence function between the boiler main control command and the fuel command. By correcting the correspondence function between the boiler main control command and the fuel command, more accurate fuel commands can be obtained, thereby ensuring the accuracy of unit fuel control and further avoiding large fluctuations in main steam pressure and temperature.

[0071] 3. This invention calculates energy signals and energy demands, and then uses these energy signals and energy demands as the controlled variable and setpoint of the PID controller to obtain the energy command output by the PID controller. Based on the energy command, the boiler main control command is obtained. When the unit is controlled through the boiler main control command, the energy coupling between the turbine and the boiler is realized, and the boiler adjustment speed is accelerated when the unit changes load rapidly.

[0072] 4. The method disclosed in this invention can improve the unit's flexible adjustment capabilities, such as primary frequency regulation and AGC, increase the unit's ancillary service revenue, and reduce the costs incurred in performance evaluations due to poor adjustment performance. It can also reduce large fluctuations in main steam pressure and temperature caused by frequent load adjustments, improving the unit's operating efficiency and economy, and lowering the risk of unit tripping due to steam temperature fluctuations. For the power grid, the application and promotion of this invention significantly enhances the flexible adjustment capabilities of thermal power units, such as frequency regulation, which is beneficial to the safe and stable operation of the power grid. Furthermore, this invention can promote the consumption of new energy sources and contribute to the construction of a new power system. In summary, this invention has good application and promotion value.

[0073] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0074] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0075] Figure 1 This is an overall flowchart of the method disclosed in the embodiment;

[0076] Figure 2 This is a flowchart of the boiler main control command acquisition process disclosed in the embodiment;

[0077] Figure 3 This is a schematic diagram illustrating the calculation of the enthalpy of the steam outlet of the steam-water separator as disclosed in the embodiment.

[0078] Figure 4 The flowchart for water instruction modification disclosed in the embodiment is shown below;

[0079] Figure 5This is a schematic diagram of the effective data segment marking disclosed in the embodiment;

[0080] Figure 6 The diagram shows the outlet temperature data of two steam-water separators disclosed in the embodiment. Detailed Implementation

[0081] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0082] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0083] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0084] Example 1

[0085] To effectively address the issue of poor regulation performance of supercritical units under deep peak shaving conditions, this embodiment discloses a dynamic optimization control method for water-coal coordination in deep peak shaving of supercritical units, which realizes dynamic optimization of supercritical units under different load sections and different operating conditions.

[0086] like Figures 1-6 As shown, the dynamic optimization control method for deep peak-shaving water-coal coordination in supercritical units includes:

[0087] Obtain unit load and boiler main control commands;

[0088] Fuel and water supply commands are obtained based on the boiler master control commands;

[0089] Determine the stage of unit load;

[0090] Based on the lag time and inertia order corresponding to the stage of unit load, the feedwater command is differentially corrected to obtain the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; extract the matching effective data segments of fuel change and feedwater change... The outlet temperature of the steam-water separator is extracted from each segment. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater variation is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel variation to obtain the optimal lag time and optimal inertia order. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle.

[0091] Coal supply is controlled via fuel commands;

[0092] The water supply is controlled by modifying the water supply command.

[0093] According to the traditional control method of supercritical units, the turbine controls the power generation and the boiler controls the main steam pressure. This control method is prone to energy imbalance between the turbine and the boiler when the unit changes load rapidly, which in turn affects the unit's regulation capability.

[0094] This embodiment is equipped with a rapid boiler main control module. When the unit rapidly changes load, the energy demand of the steam turbine is transmitted to the boiler, and the air, coal and water are quickly adjusted to realize the energy coupling between the steam turbine and the boiler, which is beneficial to the control of the main steam pressure and main steam temperature of the unit.

[0095] The control scheme for the main control module of the rapid boiler is as follows: Figure 2 As shown, the rapid boiler main control module adopts a control method of main command open-loop control + PID closed-loop control. Energy demand ST and energy signal PV are fed into the PID controller after passing through a subtractor. The unit load L is multiplied by the set coefficient K to generate the main command. The main command plus the PID output constitutes the boiler main control command. Specifically:

[0096] Obtain the main steam pressure, steam enthalpy at the steam-water separator outlet, and unit load;

[0097] The energy signal is determined by the main steam pressure;

[0098] The energy requirement is determined by the enthalpy of the steam at the outlet of the steam-water separator;

[0099] Calculate the difference between the energy signal and the energy demand, and the rate of change of this difference;

[0100] The difference between the energy signal and the energy demand, and the rate of change of the difference, are input into the PID controller, which outputs the energy command.

[0101] The boiler main control command is obtained by multiplying the unit load by a set coefficient and then adding it to the energy command.

[0102] The calculation formula for the main instruction is as shown in equation (1), where L is the unit load, which is the unit load instruction that has been modified after being sent from the central dispatch to the power plant.

[0103] Main instruction = L × K (1)

[0104] K is a set coefficient, determined according to the stage of the unit load, which can be the first stage, the second stage, or the third stage. Preferably, when the unit load is greater than or equal to 30% of the rated load Pe and less than or equal to 40% of the rated load, the unit load is in the first stage; when the unit load is greater than or equal to 50% of the rated load, the unit load is in the second stage; when the unit load is greater than 40% of the rated load and less than 50% of the rated load, the unit load is in the third stage. Above 50% of the rated load, K is set to 1; below 50% of the rated load, the smaller the load, the smaller the value of K. The specific settings of K are shown in Table 1.

[0105] Table 1

[0106] K 1 0.9 0.8

[0107] Under deep peak shaving conditions, the linearity of the unit's actuators is poor, so it is necessary to reduce the role of the rapid boiler main command and enhance the role of PID closed-loop regulation.

[0108] In traditional PID controllers for supercritical units, the controlled variable and setpoint are the main steam pressure and the main steam pressure setpoint, respectively. In order to achieve energy coupling between the turbine and the boiler and accelerate the boiler's adjustment speed when the unit experiences rapid load changes, this embodiment sets the energy signal PV and the energy demand ST as the controlled variable and setpoint of the PID controller, respectively.

[0109] This embodiment obtains the first-stage pressure of the steam turbine; divides the first-stage pressure of the steam turbine by the main steam pressure, and then multiplies it by the main steam pressure setpoint to obtain the energy signal; wherein, the main steam flow rate is obtained; and the first-stage pressure of the steam turbine is determined according to the main steam flow rate and the corresponding function between the main steam flow rate and the first-stage pressure of the steam turbine.

[0110] The energy signal PV is calculated using equation (2):

[0111]

[0112] In the formula, p z It is the main steam pressure, p st It is the main steam pressure setpoint. f(x) is the corresponding function of main steam flow rate and turbine first-stage pressure, where x is the main steam flow rate and f is the turbine first-stage pressure. This function can be the turbine's factory design value.

[0113] In this embodiment, the energy demand signal is obtained by adding the differential of the first stage pressure of the steam turbine and the enthalpy of the steam at the outlet of the separator. The energy demand ST is calculated using equation (3).

[0114]

[0115] In the formula, h c is the enthalpy of the steam at the outlet of the steam-water separator, c is the differential time constant, and s is the Laplace operator.

[0116] The process involves obtaining the outlet steam temperature and pressure of the steam separator, and determining the outlet steam enthalpy based on the steam thermodynamic properties table and the outlet steam temperature and pressure of the steam separator.

[0117] In this embodiment, the water vapor thermodynamic property table is set in an external server. A control unit is set in the external server by writing a program. The function of the control unit is to automatically find the water vapor enthalpy h (KJ / Kg) according to the water vapor thermodynamic property table given the water vapor temperature t (°C) and pressure p (MPa).

[0118] like Figure 3 As shown, given the known steam temperature and pressure at the outlet of the steam-water separator, the enthalpy of the steam at the outlet of the steam-water separator can be calculated in real time according to control unit one.

[0119] In this embodiment, the feedwater command is obtained based on the acquired boiler main control command and the corresponding function between the boiler main control command and the feedwater command; the corresponding function between the designed boiler main control command and the fuel command is modified by the ratio of the designed coal calorific value to the boiler coal calorific value; and the fuel command is obtained based on the modified function and the acquired boiler main control command.

[0120] F2(x) is the correspondence function between the boiler main control command and the feedwater, which can be obtained from the boiler design specification.

[0121] F1(x) is the modified correspondence function between the boiler main control command and the fuel command. The coal used in the boiler is usually different from the designed coal type, and the calorific value of the coal used in the boiler differs from that of the designed coal. Therefore, F1(x) needs to be modified based on the design. 1设计(x) is the correspondence function between the designed boiler main control command and fuel. This function can be obtained from the boiler design specification. The correction formula is shown in equation (4).

[0122]

[0123] When the unit changes load rapidly, the response speed of the fuel is lagging, while the response speed of the water is faster than that of the fuel. The function of the speed matching module is to make the response speed of the feedwater better match the response speed of the fuel, prevent the imbalance between the heat absorption of the feedwater and the heat release of the fuel, and thus prevent pressure and temperature fluctuations.

[0124] The technical solution for the speed matching module is as follows: Figure 4 As shown in the figure, As an inertial lag element, through The correction coefficient for the feedwater command is obtained, and multiplied by the correction coefficient to correct the feedwater command, resulting in the corrected feedwater command. This corrected feedwater command is then used as the control command for the unit's feedwater system, allowing the speed at which water acts in the boiler to better match the speed at which fuel acts in the boiler, thereby avoiding large fluctuations in main steam pressure and temperature. In the above formula, T and n represent the lag time and inertia order, respectively. These are determined based on the stage of the unit load. In this embodiment, the unit load is divided into three stages: stage one, stage two, and stage three. Preferably, stage one is when the unit load is greater than or equal to 30% of the rated load Pe and less than or equal to 40% of the rated load; stage two is when the unit load is greater than or equal to 50% of the rated load; and stage three is when the unit load is greater than 40% of the rated load and less than 50% of the rated load. The lag time and inertia order differ for different load stages to accommodate the differences in the unit's regulation characteristics under different load stages. The lag time and inertia order are automatically and dynamically calculated and automatically adjusted as the unit's operating conditions change. The first stage has a lag time of T1 and an inertial order of n1; the second stage has a lag time of T2 and an inertial order of n2; and the third stage has a lag time of T3 and an inertial order of n3.

[0125] Figure 4 AXSEL is a selection block that selects the upper loop when the condition is true and selects the lower loop when the condition is false.

[0126] In this embodiment, to accurately correct the feedwater command based on the unit load, after generating the feedwater command, the stage of the unit load is determined. Based on the lag time and inertia order corresponding to the stage of the unit load, the feedwater command is differentially corrected to obtain the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: The operating data of the unit in the previous operating cycle is acquired; based on the stage of the unit load in the operating data of the previous operating cycle, the operating data of the previous operating cycle is divided into stages, acquiring operating data for multiple stages; for each stage, matching effective data segments of fuel change and feedwater change are extracted from the operating data of that stage. The steam-water separator outlet temperature is extracted from the matched effective data segments of fuel and feedwater changes, respectively. Based on the lag time and inertia order, the steam-water separator outlet temperature extracted from the effective data segment of feedwater changes is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the steam-water separator outlet temperature extracted from the effective data segment of fuel changes, and the optimal lag time and optimal inertia order are obtained. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle are used as the lag time and inertia order corresponding to the same stage of the current operating cycle.

[0127] The process of obtaining the valid data segments of fuel change and feedwater change that match the previous operating cycle of the unit is as follows:

[0128] Obtain the operating data of the unit in the previous operating cycle, including the steam temperature at the outlet of the steam-water separator, fuel command, feedwater command and unit load;

[0129] Based on the stage of unit load in the previous operating cycle, the operating data of the previous operating cycle is divided into stages to obtain operating data for multiple stages.

[0130] For each stage of operation data, acquire all valid data segments of fuel changes and all valid data segments of feedwater changes;

[0131] Select the matching valid data segments for fuel change and feedwater change from all valid data segments for fuel change and feedwater change.

[0132] This embodiment extracts valid data segments of fuel change from the operating data based on the assumption that the feedwater command remains unchanged while the fuel command changes; it also extracts valid data segments of feedwater change from the operating data based on the assumption that the fuel command remains unchanged while the feedwater command changes; when the unit load deviation in the valid data segments of fuel change and feedwater change is within the set deviation; when the ratio of the feedwater command in the valid data segment of feedwater change to the fuel command in the valid data segment of fuel change deviates from the design value of the water-coal ratio within the set deviation range; and when the direction of change of the feedwater command in the valid data segment of feedwater change is opposite to the direction of change of the fuel command in the valid data segment of fuel change, it indicates that the valid data segments of fuel change and feedwater change are matched.

[0133] The process of determining the lag time and inertia order for each stage is the same in this embodiment. Taking the lag time T2 and inertia order n2 corresponding to the second stage as an example, the explanation is as follows.

[0134] Step 1: Obtain unit operating data at 50% or higher rated load. This data includes the steam temperature at the steam-water separator outlet, fuel command, feedwater command, and unit load. Mark the validity of the operating data and name it the "Fuel Change Valid Data Segment," denoted by L. Figure 5 As shown, the validity marking trigger condition is: the water supply command remains unchanged, while the fuel command changes. Valid data segments of fuel changes are extracted and stored; these extracted valid data segments are labeled L1, L2, L3, L4…L… n Let P represent the set of valid data segments for fuel changes, P = [L1, L2, L3, L4, ..., L...]. n The valid data segment includes four types of data: steam temperature at the outlet of the steam-water separator, fuel command, feedwater command, and unit load.

[0135] Step Two: Similarly, for unit operating data above 50% rated load, validity markers are applied and named "Feedwater Change Valid Data Segment," denoted by M. The validity marker trigger condition is: fuel command remains unchanged, feedwater command changes. The extracted feedwater change valid data segments are stored; these segments are designated M1, M2, M3, M4…M… n Let Q represent the set of valid data segments for water supply changes, where Q = [M1, M2, M3, M4...M...]. n The valid data segment includes four types of data: steam temperature at the outlet of the steam-water separator, fuel command, feedwater command, and unit load.

[0136] Step 3: Match the data segment set P and the data segment set Q to obtain the matching L and M required in this embodiment. A match is successful when one set of L and M in data segment set P and data segment set Q satisfies the following condition:

[0137] Condition 1: The load deviation of units in L and M is within the set deviation, which is 1% of the rated load.

[0138] Condition 2: (Water supply instruction in M) / (Fuel instruction in L) = Design value of water-coal ratio, and the deviation between the two is within the set deviation range, which is: design value of water-coal ratio (1 ± 5%).

[0139] Condition 3: The direction of change of the feedwater command in M ​​is opposite to the direction of change of the fuel command in L. This is because the changes in the fuel command and the feedwater command have opposite effects on the outlet temperature of the steam-water separator, therefore the direction of change of the feedwater command must be opposite to the direction of change of the fuel command.

[0140] After successful matching, a set of L and M required by the present invention can be obtained. Then, the outlet temperature of the steam-water separator is extracted from L and M respectively. The extracted two segments of steam-water separator outlet temperature data are shown in Figure 6.

[0141] Figure 6 In the data, W represents the steam-water separator outlet temperature data in the effective data segment of feedwater variation, and F represents the steam-water separator outlet temperature data in the effective data segment of fuel variation.

[0142] The steam-water separator outlet is located in the middle of the boiler's steam-water system. The outlet temperature of the steam-water separator can quickly reflect changes in the boiler's combustion energy balance. Therefore, it is feasible to deduce the lag time of fuel relative to feedwater from the steam-water separator outlet temperature. Water acts faster in the boiler than fuel, so the steam-water separator outlet temperature responds to changes in feedwater commands faster than to changes in fuel commands.

[0143] Therefore, in this embodiment, based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater changes is differentially corrected to construct a corrected temperature model, which is as follows:

[0144]

[0145] With the objective of minimizing the error between the corrected temperature and the steam-water separator outlet temperature extracted from the effective data segment of fuel variation, the corrected temperature model is solved to obtain the optimal lag time T2 and the optimal inertia order n2.

[0146] Using the same method, T1, n1, T3, and n3 can be calculated.

[0147] The optimal lag time and optimal inertia order, determined by the operating data of each stage of the previous operating cycle, will be used as the lag time and inertia order for the same stage in the current operating cycle, and the water supply commands during the current operating cycle will be corrected.

[0148] Before calculating all lag times and inertial orders in the next optimization cycle, the velocity matching module continues to use the parameters calculated last time. After a successful calculation, it automatically enters the next optimization cycle. In the next optimization cycle, the process of collecting data, processing data, and calculating lag times and inertial orders is repeated, and the calculation process is continuously looped to achieve dynamic optimization.

[0149] In this embodiment, after obtaining the fuel command and the modified water supply command, the coal feed is controlled by the fuel command, and the water supply is controlled by the modified water supply command.

[0150] Specifically, fuel control output values ​​are obtained through fuel commands; and the coal feeder is controlled based on the fuel control output values.

[0151] The water supply control output value is obtained by modifying the water supply command; the water pump is controlled according to the water supply control output value.

[0152] Preferably, the actual fuel quantity is controlled by PID control through a fuel command to obtain a fuel control output value; the actual water supply quantity is controlled by PID control through a corrected water supply command to obtain a water supply control output value.

[0153] This embodiment discloses a dynamic optimization control method for deep peak-shaving water-coal coordination in supercritical units. The method uses a rapid boiler main control module to solve for the boiler main control command, which serves as the superior level for fuel and feedwater control. The boiler main control command generates fuel and feedwater commands through two functions. The speed matching module matches the response speed of the feedwater command to the response speed of the fuel command. After passing through the speed matching module, the feedwater command is corrected. Both the fuel controller and the feedwater controller employ closed-loop PID control. The actual coal feed rate and fuel command are processed by the fuel controller to generate a fuel control output value, which is then transmitted to the coal feeder to control the fuel quantity. The actual water feed rate and the corrected feedwater command are processed by the feedwater controller to generate a feedwater control output value, which is transmitted to the water pump to control the water supply. This reduces fluctuations in the main steam temperature and pressure of the supercritical unit, improving the unit's stability. It achieves dynamic optimization of the supercritical unit under different load ranges and operating conditions. For power plants, this invention enhances the unit's flexible adjustment capabilities, such as primary frequency regulation and AGC (Automatic Generation Control), increasing ancillary service revenue and reducing performance-related costs due to poor regulation. It also reduces significant fluctuations in main steam pressure and temperature caused by frequent load adjustments, improving operating efficiency and economy while mitigating the risk of unit tripping due to temperature fluctuations. For the power grid, the application and promotion of this invention significantly improves the flexible adjustment capabilities of thermal power units, contributing to the safe and stable operation of the grid. Furthermore, it promotes the integration of new energy sources and supports the construction of new power systems. In conclusion, this invention has significant application and promotion value.

[0154] Example 2

[0155] In this embodiment, a dynamic optimization control system for deep peak-shaving water-coal coordination in supercritical units is disclosed, including:

[0156] The rapid boiler main control module is used to acquire unit load and boiler main control commands;

[0157] The instruction allocation module is used to obtain fuel instructions and feedwater instructions based on the boiler main control instructions;

[0158] The speed matching module is used to perform differential correction on the feedwater command based on the lag time and inertia order corresponding to the stage of unit load, thereby obtaining the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; and extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage. In the effective data segment of the feedwater variation, the outlet temperature of the steam-water separator is extracted. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater variation is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel variation to obtain the optimal lag time and optimal inertia order. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle.

[0159] A fuel controller is used to control the coal feed via fuel commands;

[0160] A water supply controller is used to control the water supply by means of a modified water supply command.

[0161] Example 3

[0162] In this embodiment, an electronic device is disclosed, including a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When the processor executes the computer instructions, it completes the steps described in the supercritical unit deep peak shaving water-coal coordinated dynamic optimization control method disclosed in Embodiment 1.

[0163] Example 4

[0164] In this embodiment, a computer-readable storage medium is disclosed for storing computer instructions. When the computer instructions are executed by a processor, they complete the steps described in the supercritical unit deep peak-shaving water-coal coordinated dynamic optimization control method disclosed in Embodiment 1.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A dynamic optimization control method for deep peak-shaving water-coal coordination in supercritical units, characterized in that, include: Obtain unit load and boiler main control commands; Fuel and water supply commands are obtained based on the boiler master control commands; Determine the stage of unit load; Based on the lag time and inertia order corresponding to the stage of unit load, the feedwater command is differentially corrected to obtain the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle, including the steam temperature at the steam-water separator outlet, fuel command, feedwater command, and unit load; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; from the matching... The outlet temperature of the steam-water separator is extracted from the effective data segments of fuel change and feedwater change, respectively. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater change is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel change, and the optimal lag time and optimal inertia order are obtained. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle. Coal supply is controlled via fuel commands; The water supply is controlled by modifying the water supply command.

2. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 1, characterized in that, Obtain the main steam pressure, steam enthalpy at the steam-water separator outlet, and unit load; The energy signal is determined by the main steam pressure; The energy requirement is determined by the enthalpy of the steam at the outlet of the steam-water separator; Calculate the difference between the energy signal and the energy demand, and the rate of change of this difference; The difference between the energy signal and the energy demand, and the rate of change of the difference, are input into the PID controller, which outputs the energy command. The boiler main control command is obtained by multiplying the unit load by a set coefficient and then adding it to the energy command.

3. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 2, characterized in that, Obtain the first-stage pressure of the steam turbine; The energy signal is obtained by dividing the first-stage pressure of the steam turbine by the main steam pressure and then multiplying it by the main steam pressure setpoint. or, The energy requirement is obtained by adding the differential of the first-stage pressure of the steam turbine and the enthalpy of the steam at the outlet of the steam-water separator. Alternatively, obtain the main steam flow rate; The first-stage pressure of the steam turbine is determined based on the main steam flow rate and the corresponding function between the main steam flow rate and the first-stage pressure of the steam turbine. or, Obtain the outlet steam temperature and pressure of the steam-water separator, and determine the outlet steam enthalpy value based on the steam thermodynamic properties table and the outlet steam temperature and pressure of the steam-water separator.

4. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 1, characterized in that, Based on the obtained boiler main control command and the corresponding function between the boiler main control command and the feedwater, the feedwater command is obtained; Alternatively, by designing the ratio of the calorific value of the coal type to the calorific value of the boiler coal, the corresponding function between the boiler main control command and the fuel command can be modified, and the fuel command can be obtained based on the modified function and the obtained boiler main control command. Alternatively, fuel control output values ​​can be obtained through fuel commands; the coal feeder can then be controlled based on these fuel control output values. or, The water supply control output value is obtained by modifying the water supply command; the water pump is controlled according to the water supply control output value. or, The actual fuel quantity is controlled by PID control using fuel commands to obtain the fuel control output value; Alternatively, the actual water supply can be controlled using PID control based on the modified water supply command to obtain the water supply control output value.

5. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 1, characterized in that, The current stage is either the first stage, the second stage, or the third stage. Alternatively, when the unit load is greater than or equal to 30% of the rated load and less than or equal to 40% of the rated load, the unit load is in the first stage. Alternatively, when the unit load is greater than or equal to 50% of the rated load, the unit load is in the second stage; Alternatively, when the unit load is greater than 40% of the rated load but less than 50% of the rated load, the unit load is in the third stage.

6. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 1, characterized in that, Based on the stage of unit load in the previous operating cycle, the operating data of the previous operating cycle is divided into stages to obtain operating data for multiple stages. For each stage of operation data, acquire all valid data segments of fuel changes and all valid data segments of feedwater changes; Select the matching valid data segments for fuel change and feedwater change from all valid data segments for fuel change and feedwater change.

7. The method for deep peak-shaving water-coal coordinated dynamic optimization control of supercritical units as described in claim 1, characterized in that, When the unit load deviation in the effective data segments of fuel change and feedwater change is within the set deviation; the ratio of feedwater command in the effective data segment of feedwater change to fuel command in the effective data segment of fuel change is within the set deviation range; and the direction of change of feedwater command in the effective data segment of feedwater change is opposite to the direction of change of fuel command in the effective data segment of fuel change, it indicates that the effective data segments of fuel change and feedwater change are matched. Alternatively, if the water supply command remains unchanged but the fuel command changes, extract the valid data segment of the fuel change from the operating data; Alternatively, if the fuel command remains unchanged but the feedwater command changes, the valid data segment of the feedwater change can be extracted from the operating data.

8. A dynamic optimization control system for deep peak-shaving water-coal coordination in supercritical units, characterized in that: include: The rapid boiler main control module is used to acquire unit load and boiler main control commands; The instruction allocation module is used to obtain fuel instructions and feedwater instructions based on the boiler main control instructions; The speed matching module is used to perform differential correction on the feedwater command based on the lag time and inertia order corresponding to the stage of unit load, obtaining the corrected feedwater command. The process for determining the lag time and inertia order for each stage is as follows: Obtain the operating data of the unit from the previous operating cycle, including the steam temperature at the steam-water separator outlet, fuel command, feedwater command, and unit load; divide the operating data of the previous operating cycle into stages based on the stage of unit load in the operating data, obtaining operating data for multiple stages; for each stage, extract the matching effective data segments of fuel change and feedwater change from the operating data of that stage; from... The outlet temperature of the steam-water separator is extracted from the matching effective data segments of fuel change and feedwater change. Based on the lag time and inertia order, the outlet temperature of the steam-water separator extracted from the effective data segment of feedwater change is differentially corrected to construct a corrected temperature model. The corrected temperature model is solved with the objective of minimizing the error between the corrected temperature and the outlet temperature of the steam-water separator extracted from the effective data segment of fuel change, and the optimal lag time and optimal inertia order are obtained. The optimal lag time and optimal inertia order determined by the operating data of each stage of the previous operating cycle of the unit are used as the lag time and inertia order corresponding to the same stage of the current operating cycle. A fuel controller is used to control the coal feed via fuel commands; A water supply controller is used to control the water supply by means of a modified water supply command.

9. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When the processor executes the computer instructions, it completes the steps of the deep peak-shaving water-coal coordinated dynamic optimization control method for supercritical units as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, complete the steps of the deep peak-shaving water-coal coordinated dynamic optimization control method for supercritical units as described in any one of claims 1-7.

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