Method and device for steady-state dynamic discrimination and state estimation of initial state of supercritical thermal power unit frequency modulation

Abstract

The application discloses a steady-state dynamic discrimination and state estimation method and device for an initial state of frequency modulation of a supercritical thermal power unit, obtains a control parameter variation of a boiler-turbine coordinated control system, and judges whether the unit is in a steady state; when it is judged that the unit is in the steady state, mass conservation equations, momentum conservation equations, energy conservation equations and heat exchange equations of a subcooled liquid partition and a supercritical state partition are respectively established; the energy conservation equations and the heat exchange equations of the subcooled liquid partition and the supercritical state partition are solved iteratively to obtain heat absorption and length of the subcooled liquid partition and the supercritical state partition; based on the heat exchange equations, total heat transfer coefficients of each partition are solved; the subcooled liquid partition and the supercritical state partition are discretized into a plurality of space nodes respectively; temperature of each space node in each partition is recursively calculated respectively; and the temperature and density of each space node in each partition are utilized to construct a state estimation vector of the initial state of the unit, so that the initial state precision of primary frequency modulation simulation is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of frequency regulation simulation technology for thermal power units, and particularly relates to a method and device for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation of supercritical thermal power units. Background Technology

[0002] With the increasing proportion of new energy grid connection and the growing demand for grid regulation, supercritical and ultra-supercritical thermal power units are undertaking more frequent and in-depth peak shaving and frequency regulation tasks. Under deep regulation conditions, the coupling between the boiler-turbine-control system is stronger, and the main steam parameters, reheat parameters, and fuel-feedwater response exhibit more obvious nonlinearity and lag, resulting in a significant increase in the correlation between primary frequency regulation capability and the initial thermodynamic state of the unit.

[0003] Existing power system simulation tools and commonly used thermal power unit models in engineering calculations (such as the BPA model and the typical thermal power model used in the PSASP simulation program) typically simplify the boiler into two segments: the subcooling segment and the evaporation segment are combined into the first segment, and the superheating segment or supercritical segment is considered as the second segment. During the dynamic process, three main types of constraints are considered: first, the constraint of the main steam flow rate on the rate of change of the main steam pressure; second, the momentum conservation relationship between the two segments; and third, the mass conservation relationship between each segment. In this type of model, the initial pressure and flow rate are mainly determined by the conservation of momentum and mass.

[0004] However, in a primary frequency regulation simulation initiated near the deep peak-shaving steady state, the boiler's temperature difference along the flow path is often extremely large, especially at the spatial locations corresponding to heat exchange components such as water-cooled walls, superheaters, and reheaters, where the working fluid temperature, specific enthalpy, and density change significantly along the flow path. If initial values ​​are determined solely based on momentum and mass conservation, an initial state that satisfies the pressure-flow ratio but not the temperature distribution may be obtained. This can lead to unreasonable energy abrupt changes at the beginning of the simulation, resulting in short-term drift in main steam temperature / pressure, abnormal fuel command response, or deviations in the frequency regulation power response. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and apparatus for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in supercritical thermal power units. By introducing energy conservation constraints and adopting a block lumped and explicit solution strategy, the temperature and density distribution along the boiler are accurately reconstructed under complex operating conditions such as deep peak shaving. This significantly improves the accuracy of the initial state of primary frequency regulation simulation while effectively reducing computational complexity, thus balancing high fidelity and real-time performance.

[0006] The present invention adopts the following technical solution.

[0007] This invention proposes a method for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in supercritical thermal power units, including: Obtain the changes in control parameters of the boiler-turbine coordinated control system to determine whether the unit is in a steady state; When the unit is determined to be in a steady state, the boundary temperature is determined based on the boiler inlet pressure. Based on the boundary temperature, the working fluid inside the boiler is divided into a subcooled liquid state zone and a supercritical state zone. Mass conservation equations, momentum conservation equations, energy conservation equations, and heat transfer equations are established for the subcooled liquid state zone and the supercritical state zone, respectively. Using the actual operating data of the unit, the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone are established simultaneously. The heat absorption and length of the subcooled liquid state zone and the supercritical state zone are solved iteratively. Using the heat absorption and length of each zone, the total heat transfer coefficient of each zone is solved based on the heat transfer equation. The subcooled liquid state partition and the supercritical state partition are discretized into multiple spatial nodes; the temperature of each spatial node in each partition is calculated recursively; and the state estimation vector of the initial state of the unit is constructed using the temperature and density of each spatial node in each partition.

[0008] Preferably, the control parameters of the boiler-turbine coordinated control system include: power, main steam pressure, main steam temperature, fuel command, and feedwater command; Within the identification window, at least one of the following changes—power change, main steam pressure change, main steam temperature change, fuel command change, and feedwater command change—is compared with the corresponding change judgment condition. If all the changes involved in the judgment meet the corresponding change judgment condition, the unit is judged to be in a steady state; otherwise, the unit is judged to be in a dynamic state.

[0009] Preferably, determining the boundary temperature based on the boiler inlet pressure includes: When the boiler inlet pressure is less than or equal to the critical pressure, the saturation temperature corresponding to the boiler inlet pressure is determined as the boundary temperature. When the boiler inlet pressure is greater than the critical pressure, the pseudo-critical temperature corresponding to the boiler inlet pressure, or the equivalent boundary temperature used to divide the subcooled liquid state zone and the supercritical state zone based on historical data, is determined as the boundary temperature.

[0010] Preferably, the mass conservation equation, momentum conservation equation, energy conservation equation, and heat transfer equation for the subcooled liquid zone are established, including: The boiler inlet pressure is used as the subcooled liquid zone pressure, and the boundary temperature is used as the subcooled liquid zone outlet temperature. Establish the mass conservation equation for the supercooled liquid partition; Establish the momentum conservation equation for the supercooled liquid partition; In the subcooled liquid zone, the energy conservation equation for the subcooled liquid zone is established by replacing the saturation temperature at the boiler inlet pressure with the boundary temperature, as shown in the following equation:

[0011] In the formula, For the heat absorption of the supercooled liquid zone, For quality flow, The isobaric specific heat of the working fluid in the subcooled liquid zone. The dividing temperature, This refers to the boiler inlet temperature. Calculate the logarithmic mean temperature difference of the subcooled liquid zone; based on the logarithmic mean temperature difference, establish the heat transfer equation for the subcooled liquid zone, as shown in the following equation:

[0012] In the formula, The overall heat transfer coefficient of the subcooled liquid zone, To the length of the supercooled liquid partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercooled liquid zone.

[0013] Preferably, the mass conservation equation, momentum conservation equation, energy conservation equation, and heat transfer equation for the supercritical state partition are established, including: The average value of the boiler inlet pressure and outlet pressure is used as the supercritical zone pressure; Establish the mass conservation equation for the supercritical state partition; Establish the momentum conservation equation for the supercritical state partition; The energy conservation equation for the supercritical state partition is established as follows:

[0014] In the formula, The heat absorption of the supercritical state partition. For quality flow, The isobaric specific heat of the working fluid in the supercritical state partition. The boiler outlet temperature. The inlet temperature for the supercritical state partition; Calculate the logarithmic mean temperature difference of the supercritical zone; based on the logarithmic mean temperature difference, establish the heat transfer equation for the supercritical zone, as shown in the following equation:

[0015] In the formula, The total heat transfer coefficient of the supercritical state partition. To the length of the supercritical state partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercritical state partition.

[0016] Preferably, using actual operating data of the unit, the energy conservation equations and heat transfer equations for the subcooled liquid state zone and the supercritical state zone are simultaneously established. The heat absorption and length of the subcooled liquid state zone and the supercritical state zone are iteratively solved. Using the heat absorption and length of each zone, based on the heat transfer equations, the overall heat transfer coefficient of each zone is solved, including: In the initial solution, the heat absorption and length of the cold liquid state zone and the supercritical state zone are obtained based on the specific heat of the working fluid at constant pressure set for each zone. Then, the average temperature of each zone is corrected. Based on the corrected average temperature of each zone, the specific heat of the working fluid at constant pressure of each zone is corrected. Based on the corrected specific heat of the working fluid at constant pressure of each zone, the corrected heat absorption and length of the subcooled liquid state zone and the supercritical state zone are obtained. Using the corrected heat absorption and length of each zone, the overall heat transfer coefficient of each zone is solved based on the heat transfer equation.

[0017] Preferably, the heat absorption and length of the cold liquid state zone and the supercritical state zone are obtained based on the specific heat of the working fluid at constant pressure set for each zone during the initial solution, including: In the initial solution, the specific heat of the working fluid at constant pressure was set for the subcooled liquid zone. The heat absorption of the supercooled liquid zone is calculated based on the energy conservation equation of the supercooled liquid zone. The specific heat at constant pressure of the working fluid in the supercritical state partition is set. The heat absorption of the supercritical state partition can be directly calculated based on the energy conservation equation of the supercritical state partition. And obtain the total heat exchange. ; Based on total heat exchange Heat absorption of each zone , The proportion, and the equivalent total length of the boiler Through geometric relationships and The length of the supercooled liquid partition is obtained by solving. and supercritical state partition length .

[0018] Preferably, using the corrected heat absorption and length of each zone, the overall heat transfer coefficient of each zone is solved based on the heat transfer equation, including: The equivalent heat transfer area of ​​each zone is determined by using the corrected lengths of the subcooled liquid zone and the supercritical zone; the logarithmic mean temperature difference of each zone is determined by using the corrected average temperature of the subcooled liquid zone and the supercritical zone; and the overall heat transfer coefficient of the subcooled liquid zone and the supercritical zone is calculated by inversely using the heat transfer equation, based on the corrected heat absorption of the subcooled liquid zone and the supercritical zone.

[0019] Preferably, the steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units further includes: Establish a linear constraint on the total heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition; when the total heat transfer coefficient of the subcooled liquid state partition and the supercritical state partition satisfies the linear constraint on the total heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition, it indicates that the consistency check has been passed. in, = × And linear coefficients The value range of is [2, 5]. The overall heat transfer coefficient of the subcooled liquid zone, The total heat transfer coefficient of the supercritical zone.

[0020] Preferably, the supercooled liquid state partition and the supercritical state partition are discretized into multiple spatial nodes; the temperature of each spatial node within each partition is recursively calculated, including: After consistency verification, the subcooled liquid state zone and the supercritical state zone are discretized into multiple spatial nodes. The temperature of each spatial node in each zone is calculated recursively. Based on the approximate pressure values ​​of each zone and the temperature of each spatial node, the density of each spatial node in each zone is calculated. Based on the momentum conservation equation, the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone are calculated. Using the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone that satisfy the interval theoretical pressure drop ratio constraint, the pressure friction linear distribution function of the subcooled liquid state zone and the pressure friction linear distribution function of the supercritical state zone are established to correct the density of each spatial node in each zone. Using the temperature of each spatial node in each zone and the corrected density, the state estimation vector of the unit's initial state is constructed.

[0021] Preferably, the temperature of each spatial node within each partition is calculated recursively, including: Based on the heat absorption rate per unit length of the subcooled liquid zone, the heat absorption rate per unit length of the supercritical zone, the corrected isobaric specific heat of the working fluid in the subcooled liquid zone, and the corrected isobaric specific heat of the working fluid in the supercritical zone, the temperature of each spatial node is recursively calculated based on the discrete form of the energy conservation equation.

[0022] Preferably, based on the momentum conservation equation, the pressure drop of the subcooled liquid zone and the equivalent pressure drop of the supercritical zone are calculated, including: Pressure drop at the inlet and outlet of the subcooled liquid zone As shown in the following formula:

[0023] In the formula, This represents the equivalent drag coefficient of the subcooled liquid zone. The working fluid density of the supercooled liquid zone, The working fluid flow rate for the subcooled liquid zone; Equivalent pressure drop at the inlet and outlet of the supercritical zone As shown in the following formula:

[0024] In the formula, This represents the equivalent drag coefficient for the supercritical state partition. The average density of the working fluid in the supercritical state region. The average flow velocity of the working fluid in the supercritical state region is denoted as .

[0025] Preferably, the steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units includes: distributing the total pressure drop of the boiler inlet and outlet according to the equivalent viscosity coefficient and length of each zone to obtain the theoretical pressure drop of the inlet and outlet of the subcooled liquid zone, the theoretical pressure drop of the inlet and outlet of the supercritical zone, and establishing the theoretical pressure drop ratio constraint between zones; The theoretical pressure drop ratio constraint between zones satisfies the following relationship:

[0026] In the formula, Theoretical pressure drop at the inlet and outlet of the subcooled liquid zone Theoretical pressure drop at the inlet and outlet of the supercritical zone The ratio, , The equivalent dynamic viscosity is denoted as the supercooled liquid state partition and the supercritical state partition, respectively. The equivalent diameter of the boiler. The corrected length for the supercooled liquid partition. This is the corrected length of the supercritical state partition.

[0027] Preferably, by utilizing the pressure drop of the subcooled liquid zone satisfying the theoretical pressure drop ratio constraint between zones and the equivalent pressure drop of the supercritical zone, a pressure friction linear distribution function within the subcooled liquid zone and a pressure friction linear distribution function within the supercritical zone are established, including: like and If the absolute value of the deviation is greater than the preset limit, then adjust the length of the subcooled liquid state partition and the supercritical state partition; if and If the absolute value of the deviation is not greater than the preset limit, then the pressure drop at the inlet and outlet of the subcooled liquid zone is used as the basis. A pressure friction linear distribution function is established within the subcooled liquid zone, based on the equivalent pressure drop at the inlet and outlet of the supercritical zone. Establish a pressure linear distribution function along the pressure path within the supercritical state partition.

[0028] Preferably, a state estimation vector for the initial state of the unit is constructed using the temperature and corrected density of each spatial node within each partition, including: The temperature of each spatial node within the supercooled liquid state partition constitutes the temperature sequence of the supercooled liquid state partition, and the temperature of each spatial node within the supercritical state partition constitutes the temperature sequence of the supercritical state partition. The corrected density of each spatial node in the supercooled liquid state partition constitutes the corrected density sequence of the supercooled liquid state partition, and the corrected density of each spatial node in the supercritical state partition constitutes the corrected density sequence of the supercritical state partition. The state estimation vector of the subcooled liquid zone is obtained by concatenating the temperature sequence and the corrected density sequence of the subcooled liquid zone after node completion; the state estimation vector of the supercritical zone is obtained by concatenating the temperature sequence and the corrected density sequence of the supercritical zone after node completion; the state estimation vector of the subcooled liquid zone and the state estimation vector of the supercritical zone are concatenated to obtain the state estimation vector of the unit's initial state.

[0029] In another aspect, this invention also proposes a steady-state dynamic discrimination and state estimation device for the initial state of frequency regulation in supercritical thermal power units, comprising: The steady-state dynamic discrimination module is used to acquire the changes in control parameters of the boiler-turbine coordinated control system and determine whether the unit is in a steady state. The model building module is used to determine the boundary temperature based on the boiler inlet pressure when the unit is determined to be in a steady state, and to divide the working fluid in the boiler into a subcooled liquid state zone and a supercritical state zone based on the boundary temperature; and to establish the mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation for the subcooled liquid state zone and the supercritical state zone respectively. The model solving module is used to use the actual operating data of the unit to simultaneously solve the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone, iteratively solve the heat absorption and length of the subcooled liquid state zone and the supercritical state zone, and use the heat absorption and length of each zone to solve the total heat transfer coefficient of each zone based on the heat transfer equation. The state estimation mode is used to discretize the subcooled liquid state partition and the supercritical state partition into multiple spatial nodes; the temperature of each spatial node in each partition is calculated recursively; and the state estimation vector of the initial state of the unit is constructed using the temperature and density of each spatial node in each partition.

[0030] The present invention is also a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the method.

[0031] The present invention is also a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0032] The present invention provides a method and apparatus for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in supercritical thermal power units. First, real-time operating data of the unit at the current moment is acquired, and steady-state dynamic discrimination is performed based on the changes in control parameters of the boiler-turbine coordinated control system (CCS), and a discrimination result is obtained. Then, if the discrimination result indicates that the unit is in a steady state, the boundary temperature for dividing the two zones is determined based on the boiler inlet pressure. Based on the boundary temperature, the working fluid inside the boiler is divided into an incompressible subcooled liquid zone and a compressible supercritical zone, and lumped parameter models for the two zones are established respectively. The lumped parameter model includes mass conservation equations, momentum conservation equations, energy conservation equations, and heat transfer equations based on the logarithmic mean temperature difference. Finally, based on the real-time operating data and the boundary temperature, the lumped parameter models of the two zones are solved simultaneously to obtain the zone length and total heat transfer of the two zones, as well as the initial temperature and initial density of each discrete node along the process. The zone length, total heat transfer, initial temperature, and initial density are used as initial state parameters for frequency regulation dynamic simulation. Thus, by introducing energy conservation constraints and adopting a block lumped and explicit solution strategy, the boiler temperature distribution along the process can be accurately reconstructed under complex operating conditions such as deep peak shaving. This significantly improves the accuracy of the initial state of the primary frequency regulation simulation while effectively reducing computational complexity, thus balancing high fidelity and real-time performance. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units provided by the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] This invention proposes a steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation in supercritical thermal power units, such as... Figure 1 As shown, it includes the following steps: Step 1: Obtain the changes in control parameters of the boiler-turbine coordinated control system to determine whether the unit is in a steady state.

[0036] Specifically, the real-time operating data of the unit at the current moment includes, but is not limited to: boiler inlet temperature, inlet pressure, outlet temperature, outlet pressure, mass flow rate, and metal wall temperature; the control parameters of the boiler-turbine coordinated control system (CCS) include, but are not limited to: power, main steam pressure, main steam temperature, fuel command, and feedwater command.

[0037] Furthermore, the collected real-time operating data undergoes time alignment, filtering, and outlier removal, including: ① Time alignment: Signals from different systems are aligned according to their timestamps, using nearest neighbor interpolation or linear interpolation to avoid misjudgments caused by phase differences. ② Filtering: First-order low-pass filtering or moving average can be used for temperature, pressure, and flow signals, with a filtering time constant of 5-20 seconds; the calculation of the controller output change rate should be performed after filtering. ③ Outlier removal: When a sampling point exceeds a reasonable physical range (e.g., a sudden pressure jump or a sudden temperature drop of tens of degrees), the previous value can be held or the windowed midpoint, and an alarm should be recorded.

[0038] Steady-state dynamic discrimination is performed based on the changes in control parameters of CCS, and the discrimination results are obtained. This includes: within the identification window, comparing at least one of the changes in power, main steam pressure, main steam temperature, fuel command, and feedwater command with the corresponding change judgment conditions; if all the changes involved in the discrimination meet the corresponding change judgment conditions, the controlled variables such as power, main steam pressure, and main steam temperature fluctuate within the allowable deviation range, and the control commands such as fuel command and feedwater command no longer change significantly, then the unit is judged to be in steady state; otherwise, the unit is judged to be in dynamic state.

[0039] Furthermore, in response to the unit's state transitioning from dynamic to steady state, steady-state identification is triggered after a preset time window delay. The length of the steady-state determination window is related to the sampling period. If the sampling period is 1 second, a window length of approximately 60 is recommended; if the sampling period is 2 seconds, a window length of 30-60 is recommended. A window that is too short is prone to misjudgment, while a window that is too long reduces the response speed. When determining the transition from dynamic to steady state, it is recommended to delay for several periods (e.g., 10-20 seconds) before triggering the identification to avoid the initial value being affected by the transition period immediately after entering steady state.

[0040] In this embodiment, based on the principle of retaining key quantities strongly correlated with the "steady-state determination" and "heat release trend determination" at the moment of initial frequency modulation start-up, the initial steady-state is identified. "Steady-state" refers to a state where, within the identification window (e.g., the most recent N sampling points, where N can be 30-120), the rate of change of both key thermodynamic parameters and key control outputs is less than a preset threshold, making the time term approximately zero. The steady-state determination can employ a combination of three criteria: "deviation amplitude + rate of change + consistency." The determination rules are as follows: 1) Power criterion: and In the formula, This is the unit's reference power. This represents the actual power output of the unit. The set threshold for power change. The set power change rate threshold.

[0041] 2) Main steam pressure criterion: In the formula, Main steam pressure The set threshold for the rate of change of main steam pressure.

[0042] 3) Main steam temperature criterion: In the formula, The main steam temperature is the boiler outlet working fluid temperature. The set threshold for the rate of change of main steam temperature is used to prevent the main steam temperature criterion from being mistakenly judged as steady state during the slow temperature rise phase.

[0043] 4) Fuel command criterion: The standard deviation of the fuel command within the recognition window is less than or equal to the set fuel command change threshold. Furthermore, the direction of change does not deviate continuously.

[0044] 5) Water supply command criteria: The standard deviation of the water supply command within the identification window is less than or equal to the set threshold for water supply command change. Furthermore, the direction of change does not deviate continuously.

[0045] When all of the above criteria are met, the state is determined to be steady; otherwise, it is determined to be dynamic.

[0046] In this embodiment, each threshold is set according to the actual unit capacity, signal noise, and sampling period of the project. The value is 0.1%-0.3% of the rated power. The value ranges from 0.05 to 0.2°C / s.

[0047] The judgment result also needs to be verified by the change in boiler heat release, that is, it is necessary to determine whether the primary frequency regulation process is accompanied by an increase in boiler heat release. This judgment can be determined comprehensively based on the direction and amplitude of the fuel command in CCS, the sign of the main steam pressure deviation, and the coordinated output of feedwater / fuel: if the primary frequency regulation causes an increase in valve opening, an increase in steam flow, and an upward trend in fuel command, it can be determined that the boiler heat release will increase over time; if the valve opening increases while the fuel command is restricted or decreases, there may be insufficient heat release in the short term, relying on the energy stored in the metal wall and the enthalpy drop of the working fluid for support. When the boiler heat release increases, the unit steady-state judgment is re-executed; when the boiler heat release does not increase, the unit is determined to be in steady state.

[0048] By using steady-state dynamic discrimination, dynamic transition states such as load adjustment, fuel / feedwater coordination not yet stable, and main steam parameters still rising are excluded. This avoids misidentifying dynamic processes as steady-state initial values, thereby improving the reliability of subsequent state estimation results and the consistency of initial conditions for frequency modulation simulation. It also provides more accurate model update trigger signals and key characteristic parameters for subsequent zoning modeling, thus improving the accuracy of zoning and modeling.

[0049] Step 2: When the unit is determined to be in steady state, the boundary temperature is determined based on the boiler inlet pressure. Based on the boundary temperature, the working fluid in the boiler is divided into a subcooled liquid state zone and a supercritical state zone. The mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation are established for the subcooled liquid state zone and the supercritical state zone, respectively.

[0050] Specifically, step 2 includes: Step 2.1, determine the boundary temperature for dividing the two zones based on the boiler inlet pressure, including: When the boiler inlet pressure in the real-time operating data is less than or equal to the critical pressure, the saturation temperature corresponding to the boiler inlet pressure is determined as the boundary temperature. When the boiler inlet pressure is greater than the critical pressure, the pseudo-critical temperature corresponding to the boiler inlet pressure, or the equivalent boundary temperature used to divide the subcooled liquid state zone and the supercritical state zone based on historical data, is determined as the boundary temperature.

[0051] It should be noted that when the boiler inlet pressure is less than or equal to the critical pressure At that time, the working fluid has a saturation temperature. When the boiler inlet pressure is greater than the critical pressure At that point, a strictly defined phase transition saturation line no longer exists. To make the method proposed in this invention applicable to supercritical and ultra-supercritical once-through boilers, the embodiments will... In a broader sense, this refers to the equivalent boundary temperature, calibrated based on historical data, used to delineate the subcooled liquid state and the supercritical state. .

[0052] Step 2.2: Based on the boundary temperature, the working fluid inside the boiler is divided into an incompressible subcooled liquid zone and a compressible supercritical zone.

[0053] The zoning designation allows the zoning boundaries to adaptively adjust with changes in operating pressure and working fluid properties, making it particularly suitable for scenarios with significant changes in working fluid density, specific heat, and heat transfer characteristics under deep peak shaving, sliding pressure operation, and supercritical conditions.

[0054] Under steady-state conditions, the working fluid flows along the boiler heating surface, satisfying the conservation of mass, momentum, and energy. To ensure real-time performance, this scheme lumps the continuously distributed equations by region and discretizes them in one dimension when nodes need to be filled in.

[0055] Step 2.3: Using the boiler inlet pressure as the subcooled liquid zone pressure and the boundary temperature as the subcooled liquid zone outlet temperature, establish a lumped model of the subcooled liquid zone, including: mass conservation equation, momentum conservation equation, energy conservation equation, and heat transfer equation.

[0056] Specifically, step 2.3 includes: Step 2.3.1: Establish the mass conservation equation for the supercooled liquid partition.

[0057] Under steady-state and leak-free conditions, the mass flow rate is constant throughout the friction path, and the mass conservation equation is as follows:

[0058] In the formula, For the journey Mass flow rate at the location, , These are the mass flow rates at the boiler inlet and outlet, respectively.

[0059] Step 2.3.2: Establish the momentum conservation equation for the subcooled liquid zone; calculate the pressure drop at the inlet and outlet of the subcooled liquid zone based on the momentum conservation equation.

[0060] The pressure drop along the pipe is related to frictional resistance, local resistance, and momentum change. For a one-dimensional equivalent pipe, the momentum conservation equation is as follows:

[0061] In the formula, For pressure drop along the process, This is the friction coefficient. This is the equivalent local drag coefficient. For the working fluid density, The equivalent diameter of the boiler. The equivalent total length of the boiler. The working fluid velocity.

[0062] The subcooled liquid zone is mainly the section from the water-cooled wall inlet to near the saturation temperature. The density change within the subcooled liquid zone is relatively small, and the velocity change along the path can be ignored. Therefore, the momentum conservation can be simplified to a viscous pressure drop model.

[0063] Increase the pressure of the supercooled liquid partition Given the boiler inlet pressure, the pressure drop at the inlet and outlet of the subcooled liquid zone is calculated using the following equivalent resistance model. :

[0064] In the formula, The equivalent drag coefficient for the subcooled liquid zone can be given by the design manual or identified offline through historical data; The working fluid density of the supercooled liquid zone, The working fluid flow rate is for the subcooled liquid zone.

[0065] When determining the initial value of the temperature distribution, the pressure drop determined by the equivalent resistance model can be used as a weak constraint.

[0066] Step 2.3.3: In the subcooled liquid zone, the boundary temperature is used to replace the saturation temperature under the boiler inlet pressure to establish the energy conservation equation for the subcooled liquid zone.

[0067] Considering viscous pressure drop but neglecting the effect of viscosity on physical properties, the outlet temperature of the subcooled liquid zone is determined. Approximately the saturation temperature at the boiler inlet pressure The approximate physical meaning is that the endpoint of the supercooled liquid zone is close to the saturation line and near the deep steady state. The temperature rise within the supercooled liquid zone is mainly determined by the heat absorption of the heated surface. The effect of pressure changes on the saturation temperature can be uniformly calculated by selecting the inlet pressure. The boundary temperature is used. Subsequently, the saturation temperature at the boiler inlet pressure can be uniformly replaced with the boundary temperature, thereby avoiding the inapplicability issues caused by using the concept of saturation temperature under supercritical pressure, while still maintaining the computational advantage of "explicitly solving for the boundary location". This compatibility processing is a refinement of the engineering implementation of this scheme and does not change the overall idea of ​​block-based lumped identification.

[0068] The energy conservation equation for the supercooled liquid partition is shown below:

[0069] In the formula, For the heat absorption of the supercooled liquid zone, For quality flow, The isobaric specific heat of the working fluid in the subcooled liquid zone. The dividing temperature, This refers to the boiler inlet temperature.

[0070] The energy conservation equation for the supercooled liquid partition adopts the engineering assumptions that the specific heat and pressure are approximately constant.

[0071] Step 2.3.4: Calculate the logarithmic mean temperature difference of the subcooled liquid zone; based on the logarithmic mean temperature difference, establish the heat transfer equation for the subcooled liquid zone.

[0072] Logarithmic mean temperature difference (LMTD) can be calculated according to engineering thermal standards in counter-current or parallel-current arrangements. Due to the complexity of actual boiler structures, the logarithmic mean temperature difference is replaced by an equivalent temperature difference constructed from the metal wall temperature and the working fluid temperature at the lumped-element level, or flue gas temperature is introduced when measuring / modeling on the flue gas side.

[0073] The logarithmic mean temperature difference in the heat transfer equation is an equivalent temperature difference constructed based on the metal wall temperature and the working fluid temperature. When there are multiple metal wall temperature measurement points, a weighted average method based on the proportion of heated area or length is used to construct the equivalent wall temperature for each zone. The temperature difference term in the heat transfer equation is the factor affecting... The stability of heat transfer coefficient calculation is crucial. This invention allows for various equivalent temperature difference construction methods to adapt to different measuring point configurations and boiler structural complexities, including: 1) Single-point wall temperature: When there are few temperature measurement points for water-cooled walls or superheater metal walls, the nearest measurement point can be directly taken as the average temperature of the zone. ; 2) Multi-point weighted average: When there are multiple wall temperature measuring points, the average temperature can be obtained by weighting the points according to the proportion of the heated area or length. The weights can be determined by the design heat exchange area distribution or obtained from historical data.

[0074] 3) Wall temperature field reconstruction: If a furnace heat load distribution model or flue gas side temperature field estimation is available, the wall temperature field within each zone can be estimated first, and then the equivalent logarithmic mean temperature difference of each zone can be calculated. This method offers higher accuracy but requires more computation.

[0075] 4) Flue gas side temperature introduction: When the flue gas inlet / outlet temperature is available or a furnace heat balance model is available, a counter-current LMTD of flue gas and working fluid can be constructed to further improve the temperature of each zone. Physical consistency of heat transfer coefficient.

[0076] Logarithmic mean temperature difference This can be expressed in the following form, with the metal wall temperature approximately constant or the average value taken within the partition. For example:

[0077] In the formula, The average temperature of the working fluid in the zone. The inlet working fluid temperature of the boiler. This refers to the working fluid temperature at the boiler outlet.

[0078] when - and - When the signs are inconsistent or close to 0, the logarithmic mean temperature difference Numerical instability may occur. In engineering implementations, a lower bound can be set, or a Taylor expansion approximation can be used to improve robustness.

[0079] The heat transfer equation based on the logarithmic mean temperature difference is as follows:

[0080] In the formula, The overall heat transfer coefficient of the subcooled liquid zone, To the length of the supercooled liquid partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercooled liquid zone.

[0081] in, and Association, for example = .

[0082] The energy conservation equation and the heat transfer equation are combined to solve for the heat absorption of the subcooled liquid zone. The overall heat transfer coefficient of the subcooled liquid zone .

[0083] Step 2.4: Using the average value of the boiler inlet pressure and outlet pressure as the supercritical state partition pressure, establish a lumped model of the supercritical state partition, including: mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation.

[0084] The supercritical state partition corresponds to the section where the working fluid temperature and specific enthalpy continuously increase and the density changes significantly. Under steady-state conditions, the mass flow rate remains constant along the flow path, but the flow velocity varies spatially due to density variations. In its rigorous form, momentum conservation requires simultaneous consideration of velocity, density, pressure variations along the flow path, and their coupling with the physical property equations. For real-time performance, a pressure-average assumption is adopted, weakening the influence of pressure on the working fluid's isobaric specific heat and temperature, while retaining the main nonlinearity of density variation with temperature.

[0085] Specifically, step 2.4 includes: Step 2.4.1: The average value of the boiler inlet pressure and outlet pressure is taken as the supercritical state zone pressure. ,Right now , This is the average pressure. , These are the boiler inlet pressure and outlet pressure, respectively.

[0086] Step 2.4.2: Establish the mass conservation equation for the supercritical state partition, as shown in the following equation:

[0087] In the formula, For the journey Mass flow rate at the location, , These are the mass flow rates at the boiler inlet and outlet, respectively.

[0088] Based on the mass conservation equation, the flow velocity is calculated as shown in the following formula:

[0089] In the formula, For the journey Flow velocity at that point For quality flow, For the journey The density of the working fluid at that location, The flow area is denoted as .

[0090] Step 2.4.3: Establish the momentum conservation equation for the supercritical state partition; calculate the equivalent pressure drop at the inlet and outlet of the supercritical state partition based on the momentum conservation equation.

[0091] Under the assumption of pressure mean distribution in the supercritical state, friction drag can be mainly used to determine the "qualitative pressure distribution" or for verification. The core is still determined by energy and heat transfer closure, and the equivalent pressure drop... As shown in the following formula:

[0092] In the formula, The equivalent drag coefficient for the supercritical state partition can be given by the design manual or identified offline through historical data; The average density of the working fluid in the supercritical state region. The average flow velocity of the working fluid in the supercritical state region is denoted as .

[0093] The above formula can be used as an auxiliary constraint for identifying the temperature distribution along the path.

[0094] Step 2.4.4: Establish the energy conservation equation for the supercritical state partition, as shown in the following equation:

[0095] In the formula, The heat absorption of the supercritical state partition. For quality flow, The isobaric specific heat of the working fluid in the supercritical state partition. The boiler outlet temperature. The inlet temperature of the supercritical state zone is theoretically equal to the outlet temperature of the supercooled liquid state zone. or in its vicinity.

[0096] Step 2.4.5: Calculate the logarithmic mean temperature difference of the supercritical state partition; based on the logarithmic mean temperature difference, establish the heat transfer equation of the supercritical state partition.

[0097] The heat transfer equation based on the logarithmic mean temperature difference for the supercritical state partition is shown below:

[0098] In the formula, The total heat transfer coefficient of the supercritical state partition. To the length of the supercritical state partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercritical state partition.

[0099] The energy conservation equation and the heat transfer equation are combined to solve for the heat absorption in the supercritical state region. The overall heat transfer coefficient of the supercritical state partition .

[0100] In existing technologies, the initialization of frequency regulation simulation for thermal power units typically relies on mass conservation, momentum conservation, and pressure-flow relationships to determine the initial boiler state. However, a unified closed-loop constraint is not formed between zoned heat absorption, working fluid temperature rise, and wall heat transfer. Specifically, zoned heat absorption is usually determined based on empirical proportions, average heat load, or simplified heat distribution methods; working fluid temperature rise is often obtained by interpolating inlet and outlet temperatures or empirical node temperatures; and wall heat transfer capacity is usually treated as an independent engineering verification quantity or equivalent parameter. This can lead to mismatches between zoned heat absorption and working fluid temperature rise, and inconsistencies between working fluid-side heat absorption and wall-side heat transfer. While the resulting initial state may satisfy pressure and flow constraints, it cannot accurately reflect the boiler's temperature, specific enthalpy, and density distribution along the flow path, resulting in energy imbalances during the start-up phase of frequency regulation dynamic simulation.

[0101] After determining that the unit is in a steady state in step 1, this invention uses the model provided in step 1 to update the trigger signal and key operating condition characteristic parameters, including the boiler inlet temperature, outlet temperature, inlet pressure, outlet pressure, mass flow rate, metal wall temperature, and the changing states of fuel command and feedwater command, to trigger the lumped-area modeling in step 2. Since the unit has been determined to be in a steady state, the time term in the sectional energy equation can be approximated as zero, and real-time operating parameters can be used as boundary conditions and heat transfer conditions. For each sectional, this invention simultaneously establishes the working fluid-side energy conservation equation and the wall heat transfer equation based on the logarithmic mean temperature difference, so that the heat absorption of the same sectional simultaneously satisfies: On the one hand, the heat absorption of each zone is equal to the product of the mass flow rate, the specific heat at constant pressure, and the temperature rise of the working fluid, which is determined by the temperature rise of the working fluid. On the other hand, the heat absorption of a zone is equal to the product of the total heat transfer coefficient, the heat transfer area related to the zone length, and the logarithmic mean temperature difference, which is determined by the heat transfer capacity of the wall.

[0102] Thus, a closed-loop relationship is formed between the heat absorption of each zone, the temperature rise of the working fluid, the equivalent temperature difference of the wall, the heat transfer area of ​​each zone, and the length of each zone. This closed-loop relationship means that the length of each zone and the heat absorption are no longer determined solely by empirical proportions or pressure-flow rates, but are simultaneously constrained by real-time boundary temperature, pressure, mass flow rate, metal wall temperature, and working fluid properties. This improves the physical consistency of the temperature and density distribution along the path and provides a definite thermodynamic basis for the explicit solution, single explicit correction, and initial state completion of discrete nodes in subsequent step 3.

[0103] Step 3: Using the actual operating data of the unit, the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone are established simultaneously. The heat absorption and length of the subcooled liquid state zone and the supercritical state zone are solved iteratively. Using the heat absorption and length of each zone, the total heat transfer coefficient of each zone is solved based on the heat transfer equation.

[0104] In the initial solution, the heat absorption and length of the cold liquid state zone and the supercritical state zone are obtained based on the specific heat of the working fluid at constant pressure set for each zone. Then, the average temperature of each zone is corrected. Based on the corrected average temperature of each zone, the specific heat of the working fluid at constant pressure of each zone is corrected. Based on the corrected specific heat of the working fluid at constant pressure of each zone, the corrected heat absorption and length of the subcooled liquid state zone and the supercritical state zone are obtained. Using the corrected heat absorption and length of each zone, the overall heat transfer coefficient of each zone is solved based on the heat transfer equation.

[0105] This invention, by dividing the subcooled liquid state into supercritical and supercooled states, preserves the main differences in thermodynamic properties while avoiding high-dimensional, strongly coupled solutions to the friction property equations of the entire boiler.

[0106] Specifically, step 3 includes: Step 3.1, during the initial solution, set the isobaric specific heat of the working fluid in the subcooled liquid zone. The heat absorption of the supercooled liquid zone is calculated based on the energy conservation equation of the supercooled liquid zone. The specific heat at constant pressure of the working fluid in the supercritical state partition is set. The heat absorption of the supercritical state partition can be directly calculated based on the energy conservation equation of the supercritical state partition. And obtain the total heat exchange. .

[0107] Step 3.2, based on total heat exchange Heat absorption of each zone , The proportion, and the equivalent total length of the boiler Through geometric relationships and The length of the supercooled liquid partition is obtained by explicit solution. and supercritical state partition length .

[0108] In this embodiment, under the partitioned aggregate framework, the core unknowns can be selected as { , , , }or{ , , , }.in + = .

[0109] Under the assumption that "the heat absorption rate per unit length is approximately constant", we can also introduce a relationship where the heat absorption of each zone is proportional to its length: = ×( / ), = ×( / ).

[0110] , Both the energy conservation equation and the heat transfer equation are satisfied. When the saturation temperature corresponding to the boiler inlet pressure is determined as the boundary temperature, the outlet temperature of the subcooled liquid zone is... Approximately the saturation temperature at the boiler inlet pressure Inlet temperature of supercritical zone The outlet temperature of the subcooled liquid zone is approximately equal to that of the subcooled liquid zone. The energy conservation equation is as follows:

[0111]

[0112] If further , If the value is constant or depends on the average temperature of the zone, then the right side of the above equation contains known quantities, and thus can be directly obtained. , Therefore, we can solve for... , , .

[0113] Step 3.3, based on the initial result , The average temperatures of the subcooled liquid state and the supercritical state are corrected. Based on the corrected average temperatures of the subcooled liquid state and the supercritical state, the corrected isobaric specific heat of the working fluid in the subcooled liquid state is obtained. Corrected working fluid isobaric specific heat of supercritical state partitioning ;At and Following steps 3.1 and 3.2, the corrected heat absorption of the supercooled liquid partition is obtained. and length Corrected heat absorption in supercritical state partitioning and length .

[0114] The energy conservation equation and the heat transfer equation based on the logarithmic mean temperature difference have already created a closed constraint between the heat absorption of the partition, the temperature rise of the working fluid, and the heat transfer at the wall. Therefore, the partition length and partition average temperature obtained from the first explicit solution can serve as the deterministic basis for updating the isobaric specific heat. In the explicit solution path of this invention, considering the significant temperature variation of the isobaric specific heat of the working fluid in the supercritical region in actual engineering, a "one-time correction" explicit solution strategy is proposed to balance accuracy and speed. By updating the isobaric specific heat once and then performing the explicit solution again, the main estimation error caused by the temperature variation of the isobaric specific heat in the supercritical region is compensated without performing multiple rounds of iterative solutions or increasing the complexity of solving high-dimensional nonlinear equations. This improves the accuracy of the estimation results for heat transfer, partition length, and node temperature, while also taking into account the real-time performance required for frequency modulation dynamic simulation initialization.

[0115] Step 3.4, using , , , Based on the heat transfer equation, solve , .

[0116] The equivalent heat transfer area of ​​each zone is determined using the corrected lengths of the subcooled liquid zone and the supercritical zone; the logarithmic mean temperature difference of each zone is determined using the corrected average temperatures of the subcooled liquid zone and the supercritical zone; and the heat transfer equation is used to inversely calculate the equivalent heat transfer area of ​​each zone, based on the corrected heat absorption of the subcooled liquid zone and the supercritical zone. , .

[0117] Corrected logarithmic mean temperature difference As shown in the following formula:

[0118] In the formula, The corrected average temperature of the working fluid for each zone. The inlet working fluid temperature of the boiler. This refers to the working fluid temperature at the boiler outlet.

[0119] The supercooled liquid partitioning is shown in the following formula:

[0120]

[0121] The supercritical state partitioning is shown in the following equation:

[0122]

[0123] Step 4: Establish a linear constraint on the overall heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition; , When the linear constraint on the overall heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition is satisfied, it indicates that the consistency check has been passed.

[0124] If the overall heat transfer coefficient is Approximately equal to the convective heat transfer coefficient The series coefficient, equivalent to the wall's thermal conductivity, can be expressed as follows:

[0125] In the formula, The thermal resistance of a metal wall can be calculated based on the material and its thickness. The equivalent heat transfer coefficient on the flue gas side can be considered a constant or incorporated into the equation. When flue gas side information is lacking, it can be directly used... The equivalent heat transfer coefficient to be identified.

[0126] To reduce unknowns, the overall heat transfer coefficient for the supercritical state partition is determined empirically. or convective heat transfer coefficient Overall heat transfer coefficient of the subcooled liquid zone or convective heat transfer coefficient Proportionally, in the examples, =3 ,or =3 Overall heat transfer coefficient in a supercritical partitioned lumped parameter model. Overall heat transfer coefficient in the lumped parameter model of subcooled liquid partition It satisfies the preset linear constraints; among which, = × And linear coefficients The value range is 2 to 5. The value range is derived from engineering experience. In supercritical states, changes in the working fluid properties lead to enhanced convective heat transfer, and the heat transfer intensity on the heat exchange surface and flue gas side is usually higher. This ratio is not unique and can be taken in the range of 2-5 for different units and different types of heat exchange surfaces; it is an adjustable parameter.

[0127] In the embodiments, when using =3 When applying constraints, this can be used as a basis for... or Consistency checks will be performed, and adjustments will be made as necessary. , or The construction method was modified.

[0128] Step 5: Discretize the subcooled liquid state partition and the supercritical state partition into multiple spatial nodes; recursively calculate the temperature of each spatial node in each partition; and construct the state estimation vector of the unit's initial state using the temperature and density of each spatial node in each partition.

[0129] Specifically, after consistency verification, the subcooled liquid state zone and the supercritical state zone are discretized into multiple spatial nodes; the temperature of each spatial node in each zone is calculated recursively; based on the approximate pressure values ​​of each zone and the temperature of each spatial node, the density of each spatial node in each zone is calculated; based on the momentum conservation equation, the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone are calculated; using the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone that satisfy the interval theoretical pressure drop ratio constraint, the pressure friction linear distribution function of the subcooled liquid state zone and the pressure friction linear distribution function of the supercritical state zone are established to correct the density of each spatial node in each zone; using the temperature of each spatial node in each zone and the corrected density, the state estimation vector of the unit's initial state is constructed.

[0130] Based on the known boiler inlet and outlet temperatures, pressures, mass flow rates, and boundary temperatures, the lengths of the subcooled section and supercritical section, the heat absorption of each zone, and the total heat transfer are explicitly obtained. Furthermore, the initial temperatures and densities of each discrete node along the process are recursively derived. Compared to initialization methods using average temperatures, empirical node values, or only satisfying the pressure-flow relationship, the output node initial states simultaneously satisfy zoned energy conservation, overall heat transfer constraints, and working fluid property relationships. This reduces energy imbalance during dynamic simulation startup and minimizes short-term drift in main steam temperature / pressure, abnormal fuel command responses, or frequency modulation power response deviations.

[0131] Specifically, step 5 includes: Step 5.1: Discretize the supercooled liquid state partition and the supercritical state partition into multiple spatial nodes; recursively calculate the temperature of each spatial node in the supercooled liquid state partition and the supercritical state partition respectively.

[0132] Based on the heat absorption rate per unit length of the subcooled liquid zone Heat absorption rate per unit length of supercritical zone Corrected specific heat at constant pressure of the working fluid in the subcooled liquid zone Corrected isobaric specific heat of working fluid in supercritical state partitioning Based on the discrete form of the energy conservation equation, the temperature of each spatial node is recursively calculated.

[0133] We assume that the heat flux is the same at all points in the space, meaning that the heat absorption rate per unit length within the partition is approximately constant. This assumption is reasonable under the following conditions: 1) Near the steady state of deep adjustment, the combustion conditions are relatively stable, and the furnace heat load changes slowly along the height distribution.

[0134] 2) The partition length does not cross the boundary of the component with a sudden change in heat transfer mechanism, or the sudden change component has been divided into different partitions through partitioning.

[0135] 3) When the number of online measurement points is limited and the heat flow distribution along the path cannot be reliably reconstructed, using a constant heat absorption rate per unit length can avoid ill-posed problems.

[0136] When higher accuracy is required, it can be extended to a "piecewise constant heat flux" or "linear heat flux" model. For example, the subcooled section can be further divided into two sections, and values ​​can be taken from each section. , Or let along the way Heat absorption rate per unit length This is the baseline value for heat absorption rate per unit length. This is a proportionality coefficient. The number of unknowns increases, but it can be obtained by introducing more measuring points (such as intermediate temperature measuring points or wall temperature measuring points) or through offline calibration. The above extension is an equivalent improvement to this scheme and still falls within the overall concept of "block-based lumped identification".

[0137] The temperatures of each spatial node within the supercooled liquid state region constitute the temperature sequence of the supercooled liquid state region, and the temperatures of each spatial node within the supercritical state region constitute the temperature sequence of the supercritical state region.

[0138] In this embodiment, to meet the initial values ​​of spatial nodes required by dynamic simulation, initial state estimation is necessary. Using the partition length and heat absorption after consistency verification, a state estimation vector representing the distribution of temperature, density, etc., along the path is constructed within each partition. Within each partition, the vectors are uniformly discretized according to their length. , Each spatial node is used to construct a temperature sequence for the supercooled liquid zone. , Supercritical state partitioned temperature sequence , .

[0139] The heat absorption rate per unit length of the subcooled liquid zone is Spatial node length Heat absorption rate per unit length of supercritical zone Spatial node length Then the heat absorbed by each spatial node within the supercooled liquid partition is The heat absorption of each spatial node within the supercritical state partition is .

[0140] Based on the discrete form of the energy conservation equation, the temperature of each spatial node is calculated recursively, as shown in the following equation:

[0141]

[0142] In the formula, The first in the supercooled liquid zone The temperature of each spatial node The first supercritical state partition Temperature of each spatial node.

[0143] Step 5.2: Calculate the approximate pressure values ​​for the supercooled liquid state partition and the supercritical state partition; based on the approximate pressure values ​​for each partition and the temperature of each spatial node, calculate the density of each spatial node within each partition.

[0144] Since the outlet temperature of the subcooled liquid zone is approximated by the saturation temperature at the boiler inlet pressure, it is necessary to construct a function of saturation temperature versus pressure within the boiler inlet and outlet pressure range. In engineering implementation, one of the following methods can be adopted: 1) Table lookup and interpolation: Based on the tables of thermodynamic properties of water and water vapor, pre-establish the pressure and saturation temperature. Discrete tables are obtained using linear interpolation or cubic spline interpolation during online computation. The table lookup method is simple to implement and highly robust.

[0145] 2) Function fitting: Fitting the function using a polynomial / rational function within the target pressure range. Furthermore, the fitting accuracy is controlled by the maximum error constraint; function fitting can reduce online interpolation operations and facilitate embedded implementation.

[0146] 3) Standard property formulas: The saturation temperature can be directly calculated by calling property calculation modules that conform to standards such as IAPWS-IF97. This method has high accuracy but is more complex to implement.

[0147] This invention adopts a construction method based on actual engineering needs. In this approach, lookup table interpolation or function fitting are preferred to improve real-time calculation speed.

[0148] In this embodiment, the boiler inlet pressure is used as the subcooled liquid zone pressure, and the density of each spatial node within the subcooled liquid zone is... , Density function representing pressure and temperature, density sequence of supercooled liquid partitions , ; In this embodiment, the average value of the boiler inlet pressure and outlet pressure is used. As the partitioning pressure of the supercritical state, the density of each spatial node within the supercritical state partition. , Density function representing pressure and temperature, supercritical state partitioned density sequence , .

[0149] If the online system lacks a complete density function, a lookup table / piecewise linear fitting method can be used to achieve this.

[0150] Step 5.3: Based on the momentum conservation equation, calculate the pressure drop at the inlet and outlet of the subcooled liquid zone, and calculate the equivalent pressure drop at the inlet and outlet of the supercritical zone.

[0151] Supercooled liquid zone pressure The pressure drop between the boiler inlet pressure and the inlet and outlet of the subcooled liquid zone. As shown in the following formula:

[0152] In the formula, The equivalent drag coefficient for the subcooled liquid zone can be given by the design manual or identified offline through historical data; The working fluid density of the supercooled liquid zone, The working fluid flow rate is for the subcooled liquid zone.

[0153] Under the assumption of pressure mean, the equivalent pressure drop at the inlet and outlet of the supercritical state partition. As shown in the following formula:

[0154] In the formula, The equivalent drag coefficient for the supercritical state partition can be given by the design manual or identified offline through historical data; The average density of the working fluid in the supercritical state region. The average flow velocity of the working fluid in the supercritical state region is denoted as .

[0155] Step 5.4: Distribute the total pressure drop of the boiler inlet and outlet according to the equivalent viscosity coefficient and length of each zone to obtain the theoretical pressure drop of the inlet and outlet of the subcooled liquid zone and the theoretical pressure drop of the inlet and outlet of the supercritical zone, and establish the theoretical pressure drop ratio constraint between zones.

[0156] Total pressure drop at boiler inlet and outlet is , This refers to the boiler outlet pressure. The theoretical pressure drop ratio constraint between zones satisfies the following relationship:

[0157] In the formula, , These are the equivalent dynamic viscosities for the supercooled liquid state region and the supercritical state region, respectively. In this embodiment, the values ​​corresponding to the corrected average temperature of each region are used. This is the equivalent diameter of the boiler.

[0158] Step 5.5: Using the pressure drop of the subcooled liquid zone that satisfies the theoretical pressure drop ratio constraint between zones and the equivalent pressure drop of the supercritical zone, establish the pressure friction linear distribution function in the subcooled liquid zone and the pressure friction linear distribution function in the supercritical zone.

[0159] like and If the absolute value of the deviation is greater than the preset limit, then adjust the length of the subcooled liquid state partition and the supercritical state partition; if and If the absolute value of the deviation is not greater than the preset limit, then the pressure drop at the inlet and outlet of the subcooled liquid zone is used as the basis. A pressure friction linear distribution function is established within the subcooled liquid zone, based on the equivalent pressure drop at the inlet and outlet of the supercritical zone. Establish a pressure linear distribution function along the pressure path within the supercritical state partition.

[0160] In this invention, step 3.3 executes an active trigger correction strategy, while step 5.5 is a passive trigger correction strategy under the constraint of consistent pressure drop ratios in each partition, thereby improving the accuracy of temperature and density distribution estimation. However, compared to the active trigger correction in step 3.3, the correction proposed in step 5.5 is actually a weak constraint or auxiliary constraint. In the embodiment, the preset limit value is determined to be 0.05 based on multiple simulation test data.

[0161] The pressure distribution function along the friction path within the subcooled liquid zone is shown in the following equation:

[0162] In the formula, For the supercooled liquid zone along the path The pressure at the location.

[0163] The pressure linear distribution function along the friction zone within the supercritical state is shown in the following equation:

[0164] In the formula, For the supercritical state partition along the path The pressure at the location.

[0165] Step 5.6: Based on the pressure friction linear distribution function in the cold liquid state partition and the pressure friction linear distribution function in the supercritical state partition, correct the density of each spatial node in each partition.

[0166] The pressure along the friction linear distribution function within a zone can be used to improve density lookup tables or to verify the consistency of momentum constraints.

[0167] Step 5.7: The temperature of each spatial node in the supercooled liquid zone constitutes the temperature sequence of the supercooled liquid zone, and the temperature of each spatial node in the supercritical zone constitutes the temperature sequence of the supercritical zone; the corrected density of each spatial node in the supercooled liquid zone constitutes the corrected density sequence of the supercooled liquid zone, and the corrected density of each spatial node in the supercritical zone constitutes the corrected density sequence of the supercritical zone. The state estimation vector of the subcooled liquid zone is obtained by concatenating the temperature sequence and the corrected density sequence of the subcooled liquid zone after node completion; the state estimation vector of the supercritical zone is obtained by concatenating the temperature sequence and the corrected density sequence of the supercritical zone after node completion; the state estimation vector of the subcooled liquid zone and the state estimation vector of the supercritical zone are concatenated to obtain the state estimation vector of the unit's initial state.

[0168] By further converting the partition parameters into initial temperature and density sequences that correspond one-to-one with the nodes of the dynamic simulation model, the state vector required for frequency modulation dynamic simulation is directly generated, thus avoiding initial transient errors.

[0169] The initial state parameters output by this invention must be consistent with the subsequent frequency modulation dynamic simulation model in terms of "state variable definition, segmented structure, unit system, and sign direction".

[0170] In another aspect, this invention also proposes a steady-state dynamic discrimination and state estimation device for the initial state of frequency regulation in supercritical thermal power units, comprising: The steady-state dynamic discrimination module is used to acquire the changes in control parameters of the boiler-turbine coordinated control system and determine whether the unit is in a steady state. The model building module is used to determine the boundary temperature based on the boiler inlet pressure when the unit is determined to be in a steady state, and to divide the working fluid in the boiler into a subcooled liquid state zone and a supercritical state zone based on the boundary temperature; and to establish the mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation for the subcooled liquid state zone and the supercritical state zone respectively. The model solving module is used to use the actual operating data of the unit to simultaneously solve the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone, iteratively solve the heat absorption and length of the subcooled liquid state zone and the supercritical state zone, and use the heat absorption and length of each zone to solve the total heat transfer coefficient of each zone based on the heat transfer equation. The state estimation mode is used to discretize the subcooled liquid state partition and the supercritical state partition into multiple spatial nodes; the temperature of each spatial node in each partition is calculated recursively; and the state estimation vector of the initial state of the unit is constructed using the temperature and density of each spatial node in each partition.

[0171] To address the aforementioned technical problems in related technologies, this invention provides a method for determining the steady-state dynamics and estimating the initial state of frequency regulation in supercritical thermal power units. This method is based on boiler design parameters and real-time operational measurements. It uses key control variables from the CCS (Computer-Controlled System) to determine whether the initial state is steady-state or dynamic. Under steady-state conditions, it constructs a simultaneous equation set consisting of property equations, energy conservation equations, and overall heat transfer equations. Simultaneously, it divides the boiler working fluid into two regions: an incompressible subcooled liquid state and a compressible supercritical state. It performs partitioned lumped modeling to simplify the property coupling relationship and explicitly solves for the partition length, heat transfer, and thermodynamic state parameters along the friction nodes.

[0172] The implementation process of this scheme is illustrated using a supercritical once-through boiler unit with a rated capacity of 600MW as an example. The numerical values ​​mentioned are for illustrative purposes only and do not constitute a limitation on the scope of protection of this scheme.

[0173] (1) Input and boundary conditions: During the deep peak shaving steady-state operation, the following parameters were collected: feedwater inlet temperature 230℃, boiler inlet pressure 24.5MPa, boiler outlet main steam temperature 535℃, boiler outlet pressure 23.8MPa, and mass flow rate 1200kg / s. The weighted average of the metal wall temperature measuring points yielded an equivalent average temperature of 320℃ for the subcooled liquid zone. The equivalent average temperature of the supercritical zone is 620℃, the equivalent boiler length is 150m, and the equivalent heat transfer area is 52000. .

[0174] (2) Steady-state determination: Within the most recent 60s window, : If the power is less than 0.2% of the rated power, the main steam pressure change rate is less than 0.01 MPa / s, and the fuel / feed water command change rates are both less than the threshold, it is determined to be in steady state and enters steady state identification.

[0175] (3) Boundary temperature: Since the boiler inlet pressure is greater than the critical pressure, the pseudo-critical temperature corresponding to the boiler inlet pressure is the boundary temperature. In engineering implementation, the boundary temperature can be found to be 385°C by looking up a table. Therefore, the outlet temperature of the subcooled liquid zone and the inlet temperature of the supercritical zone are taken as the boundary temperature. By dividing the working fluid into incompressible subcooled liquid and compressible supercritical states for partitioning and lumping, the coupling degree of the physical property equations is reduced, significantly reducing computational complexity and improving online identification speed.

[0176] (4) Specific heat selection: The isobaric specific heat of the working fluid in the subcooled liquid zone is taken as 5.0. The isobaric specific heat of the working fluid in the supercritical state region is taken as 6.5. .

[0177] (5) Explicitly solve for the heat absorption and length of the subcooled liquid zone and the supercritical zone, since Usually greater than , The length is relatively longer, and the interface is located closer to the lower part of the furnace, which conforms to the heat absorption distribution characteristics of supercritical boilers under deep-tuning conditions. An explicit solution approach can output the length, heat absorption, and initial node values ​​within a finite number of steps, without requiring extensive iterations, making it suitable for deployment on unit real-time monitoring platforms or grid-side evaluation systems.

[0178] Explicitly incorporating energy conservation and overall heat transfer closure in the initial state identification process can reconstruct the boiler's temperature distribution along the flow path, avoiding sudden energy changes during the simulation startup phase and improving the reliability of primary frequency regulation simulation. Traditional methods typically determine the pressure-flow relationship through momentum equations and drag characteristics to match the initial main steam flow rate with the main steam pressure; however, due to the lack of energy conservation and overall heat transfer closure, the temperature distribution along the flow path may have multiple feasible solutions (ill-posed). A common approach is to average or take empirical values ​​for the zone temperatures. Thus, at the start of the dynamic simulation, when the energy equations begin to take effect, an "energy error correction" process occurs, manifested as a rapid drift in temperature or enthalpy. This scheme treats energy conservation as a constraint of equal importance to momentum and mass, and by clearly defining the boundary temperatures, ensures that the heat absorption in the subcooled and supercritical sections is closed in the initial stage; furthermore, by completing the nodes, a unique and continuous temperature distribution is obtained through recursion along the flow path, thereby significantly reducing the transient error during simulation startup.

[0179] (6) Inverse calculation of heat transfer coefficient , ,like With 3 If the deviation is large, a correction may be triggered.

[0180] (7) Node completion: take =10、 =20, the subcooled liquid state partition and the supercritical state partition are discretized respectively, and the node temperature is obtained by recursion; then the density is obtained by looking up the table, and then the initial vector of the boiler dynamic simulation is obtained.

[0181] (8) Result Check: When the initial values ​​of the nodes are input into the dynamic simulation model, under the condition of no external disturbance during the steady-state operation of deep peak shaving, the main steam temperature and pressure do not show non-physical jumps within a few seconds; when the primary frequency regulation is started, the trend of the main steam parameters is consistent with the field, indicating that the initial value identification meets the energy closure and the rationality of the temperature along the process. It can be connected with the CCS / DEH control model to provide a unified initial value generation mechanism for the evaluation of the primary frequency regulation capability of the unit under deep peak shaving, parameter tuning and simulation verification.

[0182] It should be noted that the method for steady-state dynamic discrimination and state estimation of the initial frequency regulation state of a supercritical thermal power unit provided in this embodiment of the invention can be executed by a device for steady-state dynamic discrimination and state estimation of the initial frequency regulation state of a supercritical thermal power unit, or by a control module within that device for executing the method. This embodiment of the invention uses the execution of the method by the device for steady-state dynamic discrimination and state estimation of the initial frequency regulation state of a supercritical thermal power unit as an example to illustrate the device provided in this embodiment of the invention.

[0183] It should be noted that, in the embodiments of the present invention, the methods shown in the accompanying drawings for the initial steady-state dynamic discrimination and state estimation of frequency regulation of supercritical thermal power units are all illustrated by way of example with reference to one accompanying drawing in the embodiments of the present invention. In specific implementation, the methods shown in the accompanying drawings for the initial steady-state dynamic discrimination and state estimation of frequency regulation of supercritical thermal power units can also be implemented in conjunction with any other accompanying drawings shown in the above embodiments, which will not be elaborated here.

[0184] In another aspect, this invention also proposes a steady-state dynamic discrimination and state estimation device for the initial state of frequency regulation in supercritical thermal power units, comprising: The steady-state dynamic discrimination module is used to acquire the changes in control parameters of the boiler-turbine coordinated control system and determine whether the unit is in a steady state. The model building module is used to determine the boundary temperature based on the boiler inlet pressure when the unit is determined to be in a steady state, and to divide the working fluid in the boiler into a subcooled liquid state zone and a supercritical state zone based on the boundary temperature; and to establish the mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation for the subcooled liquid state zone and the supercritical state zone respectively. The model solving module is used to use the actual operating data of the unit to simultaneously solve the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone, iteratively solve the heat absorption and length of the subcooled liquid state zone and the supercritical state zone, and use the heat absorption and length of each zone to solve the total heat transfer coefficient of each zone based on the heat transfer equation. The state estimation mode is used to discretize the subcooled liquid state partition and the supercritical state partition into multiple spatial nodes; the temperature of each spatial node in each partition is calculated recursively; and the state estimation vector of the initial state of the unit is constructed using the temperature and density of each spatial node in each partition.

[0185] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0186] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0187] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0188] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0189] 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 protection scope of the claims of the present invention.

Claims

1. A method for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in a supercritical thermal power unit, characterized in that, include: Obtain the changes in control parameters of the boiler-turbine coordinated control system to determine whether the unit is in a steady state; When the unit is determined to be in a steady state, the boundary temperature is determined based on the boiler inlet pressure. Based on the boundary temperature, the working fluid inside the boiler is divided into a subcooled liquid state zone and a supercritical state zone. Mass conservation equations, momentum conservation equations, energy conservation equations, and heat transfer equations are established for the subcooled liquid state zone and the supercritical state zone, respectively. Using the actual operating data of the unit, the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone are established simultaneously. The heat absorption and length of the subcooled liquid state zone and the supercritical state zone are solved iteratively. Using the heat absorption and length of each zone, the total heat transfer coefficient of each zone is solved based on the heat transfer equation. The subcooled liquid state partition and the supercritical state partition are discretized into multiple spatial nodes respectively; The temperature of each spatial node in each partition is calculated recursively; using the temperature and density of each spatial node in each partition, a state estimation vector of the unit's initial state is constructed.

2. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 1, characterized in that, The control parameters of the boiler-turbine coordinated control system include: power, main steam pressure, main steam temperature, fuel command, and feedwater command. Within the identification window, at least one of the following changes—power change, main steam pressure change, main steam temperature change, fuel command change, and feedwater command change—is compared with the corresponding change judgment condition. If all the changes involved in the judgment meet the corresponding change judgment condition, the unit is judged to be in a steady state; otherwise, the unit is judged to be in a dynamic state.

3. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 1, characterized in that, The determination of the boundary temperature based on the boiler inlet pressure includes: When the boiler inlet pressure is less than or equal to the critical pressure, the saturation temperature corresponding to the boiler inlet pressure is determined as the boundary temperature. When the boiler inlet pressure is greater than the critical pressure, the pseudo-critical temperature corresponding to the boiler inlet pressure, or the equivalent boundary temperature used to divide the subcooled liquid state zone and the supercritical state zone based on historical data, is determined as the boundary temperature.

4. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 1, characterized in that, The establishment of the mass conservation equation, momentum conservation equation, energy conservation equation, and heat transfer equation for the subcooled liquid zone includes: The boiler inlet pressure is used as the subcooled liquid zone pressure, and the boundary temperature is used as the subcooled liquid zone outlet temperature. Establish the mass conservation equation for the supercooled liquid partition; Establish the momentum conservation equation for the supercooled liquid partition; In the subcooled liquid zone, the energy conservation equation for the subcooled liquid zone is established by replacing the saturation temperature at the boiler inlet pressure with the boundary temperature, as shown in the following equation: In the formula, For the heat absorption of the supercooled liquid zone, For quality flow, The specific heat at constant pressure of the working fluid in the subcooled liquid zone. The dividing temperature, This refers to the boiler inlet temperature. Calculate the logarithmic mean temperature difference of the subcooled liquid zone; based on the logarithmic mean temperature difference, establish the heat transfer equation for the subcooled liquid zone, as shown in the following equation: In the formula, The overall heat transfer coefficient of the subcooled liquid zone, To the length of the supercooled liquid partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercooled liquid zone.

5. The method for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation of supercritical thermal power units according to claim 1, characterized in that, The mass conservation equation, momentum conservation equation, energy conservation equation, and heat transfer equation for establishing the supercritical state partitioning include: The average value of the boiler inlet pressure and outlet pressure is used as the supercritical zone pressure; Establish the mass conservation equation for the supercritical state partition; Establish the momentum conservation equations for the supercritical state partitions; The energy conservation equation for the supercritical state partition is established as follows: In the formula, The heat absorption of the supercritical state partition. For quality flow, The isobaric specific heat of the working fluid in the supercritical state partition. The boiler outlet temperature. The inlet temperature for the supercritical state partition; Calculate the logarithmic mean temperature difference of the supercritical zone; based on the logarithmic mean temperature difference, establish the heat transfer equation for the supercritical zone, as shown in the following equation: In the formula, The total heat transfer coefficient of the supercritical state partition. To the length of the supercritical state partition The relevant equivalent heat transfer area, This represents the logarithmic mean temperature difference of the supercritical state partition.

6. The method for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation of supercritical thermal power units according to claim 1, characterized in that, The method utilizes actual operating data of the unit to simultaneously establish the energy conservation equations and heat transfer equations for the subcooled liquid state zone and the supercritical state zone. Iteratively, the heat absorption and length of the subcooled liquid state zone and the supercritical state zone are solved. Using the heat absorption and length of each zone, based on the heat transfer equations, the overall heat transfer coefficient of each zone is calculated, including: In the initial solution, the heat absorption and length of the cold liquid state zone and the supercritical state zone are obtained based on the specific heat of the working fluid at constant pressure set for each zone. Then, the average temperature of each zone is corrected. Based on the corrected average temperature of each zone, the specific heat of the working fluid at constant pressure of each zone is corrected. Based on the corrected specific heat of the working fluid at constant pressure of each zone, the corrected heat absorption and length of the subcooled liquid state zone and the supercritical state zone are obtained. Using the corrected heat absorption and length of each zone, the overall heat transfer coefficient of each zone is solved based on the heat transfer equation.

7. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 6, characterized in that, The initial solution, based on the specific heat of the working fluid at constant pressure set for each zone, yields the heat absorption and length of the cold liquid zone and the supercritical zone, including: In the initial solution, the specific heat of the working fluid at constant pressure was set for the subcooled liquid zone. The heat absorption of the supercooled liquid zone is calculated based on the energy conservation equation of the supercooled liquid zone. The specific heat at constant pressure of the working fluid in the supercritical state partition is set. The heat absorption of the supercritical state partition can be directly calculated based on the energy conservation equation of the supercritical state partition. And obtain the total heat exchange. ; Based on total heat exchange Heat absorption of each zone , The proportion, and the equivalent total length of the boiler Through geometric relationships and The length of the supercooled liquid partition is obtained by solving. and supercritical state partition length .

8. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 7, characterized in that, The process involves using the corrected heat absorption and length of each zone, and based on the heat transfer equation, to solve for the overall heat transfer coefficient of each zone, including: The equivalent heat transfer area of ​​each zone is determined by using the corrected lengths of the subcooled liquid zone and the supercritical zone; the logarithmic mean temperature difference of each zone is determined by using the corrected average temperature of the subcooled liquid zone and the supercritical zone; and the overall heat transfer coefficient of the subcooled liquid zone and the supercritical zone is calculated by inversely using the heat transfer equation, based on the corrected heat absorption of the subcooled liquid zone and the supercritical zone.

9. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 8, characterized in that, Also includes: Establish a linear constraint on the total heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition; when the total heat transfer coefficient of the subcooled liquid state partition and the supercritical state partition satisfies the linear constraint on the total heat transfer coefficient between the subcooled liquid state partition and the supercritical state partition, it indicates that the consistency check has been passed. in, = × And linear coefficients The value range of is [2, 5]. The overall heat transfer coefficient of the subcooled liquid zone, The total heat transfer coefficient of the supercritical zone.

10. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 9, characterized in that, The supercooled liquid state partition and the supercritical state partition are discretized into multiple spatial nodes respectively; The temperature of each spatial node within each partition is calculated recursively, including: After consistency verification, the subcooled liquid state zone and the supercritical state zone are discretized into multiple spatial nodes. The temperature of each spatial node in each zone is calculated recursively. Based on the approximate pressure values ​​of each zone and the temperature of each spatial node, the density of each spatial node in each zone is calculated. Based on the momentum conservation equation, the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone are calculated. Using the pressure drop of the subcooled liquid state zone and the equivalent pressure drop of the supercritical state zone that satisfy the interval theoretical pressure drop ratio constraint, the pressure friction linear distribution function of the subcooled liquid state zone and the pressure friction linear distribution function of the supercritical state zone are established to correct the density of each spatial node in each zone. Using the temperature of each spatial node in each zone and the corrected density, the state estimation vector of the unit's initial state is constructed.

11. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 10, characterized in that, The recursive calculation of the temperature of each spatial node within each partition includes: Based on the heat absorption rate per unit length of the subcooled liquid zone, the heat absorption rate per unit length of the supercritical zone, the corrected isobaric specific heat of the working fluid in the subcooled liquid zone, and the corrected isobaric specific heat of the working fluid in the supercritical zone, the temperature of each spatial node is recursively calculated based on the discrete form of the energy conservation equation.

12. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of supercritical thermal power units according to claim 11, characterized in that, The calculation of the pressure drop in the supercooled liquid zone and the equivalent pressure drop in the supercritical zone based on the momentum conservation equation includes: Pressure drop at the inlet and outlet of the subcooled liquid zone As shown in the following formula: In the formula, This represents the equivalent drag coefficient of the subcooled liquid zone. The working fluid density of the supercooled liquid zone, The working fluid flow rate for the subcooled liquid zone; Equivalent pressure drop at the inlet and outlet of the supercritical zone As shown in the following formula: In the formula, The equivalent drag coefficient for the supercritical state partition. The average density of the working fluid in the supercritical state region. The average flow velocity of the working fluid in the supercritical state region is denoted as .

13. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 12, characterized in that, The total pressure drop at the boiler inlet and outlet is distributed according to the equivalent viscosity coefficient and length of each zone to obtain the theoretical pressure drop at the inlet and outlet of the subcooled liquid zone and the theoretical pressure drop at the inlet and outlet of the supercritical zone, and to establish the theoretical pressure drop ratio constraint between zones. The theoretical pressure drop ratio constraint between zones satisfies the following relationship: In the formula, Theoretical pressure drop at the inlet and outlet of the subcooled liquid zone Theoretical pressure drop at the inlet and outlet of the supercritical zone The ratio, , The equivalent dynamic viscosity is denoted as the supercooled liquid state partition and the supercritical state partition, respectively. The equivalent diameter of the boiler. The corrected length for the supercooled liquid partition. This is the corrected length of the supercritical state partition.

14. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 13, characterized in that, The method utilizes the pressure drop of the subcooled liquid zone, which satisfies the theoretical pressure drop ratio constraint between zones, and the equivalent pressure drop of the supercritical zone to establish the pressure friction linear distribution function within the subcooled liquid zone and the pressure friction linear distribution function within the supercritical zone, including: like and If the absolute value of the deviation is greater than the preset limit, then adjust the length of the subcooled liquid state partition and the supercritical state partition; if and If the absolute value of the deviation is not greater than the preset limit, then the pressure drop at the inlet and outlet of the subcooled liquid zone is used as the basis. A pressure friction linear distribution function is established within the subcooled liquid zone, based on the equivalent pressure drop at the inlet and outlet of the supercritical zone. Establish a pressure linear distribution function along the pressure path within the supercritical state partition.

15. The steady-state dynamic discrimination and state estimation method for the initial state of frequency regulation of a supercritical thermal power unit according to claim 14, characterized in that, The process of constructing a state estimation vector for the initial state of the unit using the temperature and corrected density of each spatial node within each partition includes: The temperature of each spatial node within the supercooled liquid state partition constitutes the temperature sequence of the supercooled liquid state partition, and the temperature of each spatial node within the supercritical state partition constitutes the temperature sequence of the supercritical state partition. The corrected density of each spatial node in the supercooled liquid state partition constitutes the corrected density sequence of the supercooled liquid state partition, and the corrected density of each spatial node in the supercritical state partition constitutes the corrected density sequence of the supercritical state partition. The state estimation vector of the subcooled liquid zone is obtained by concatenating the temperature sequence and the corrected density sequence of the subcooled liquid zone after node completion; the state estimation vector of the supercritical zone is obtained by concatenating the temperature sequence and the corrected density sequence of the supercritical zone after node completion; the state estimation vector of the subcooled liquid zone and the state estimation vector of the supercritical zone are concatenated to obtain the state estimation vector of the unit's initial state.

16. A device for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in a supercritical thermal power unit, used to implement the method for steady-state dynamic discrimination and state estimation of the initial state of frequency regulation in a supercritical thermal power unit as described in any one of claims 1 to 15, characterized in that, include: The steady-state dynamic discrimination module is used to acquire the changes in control parameters of the boiler-turbine coordinated control system and determine whether the unit is in a steady state. The model building module is used to determine the boundary temperature based on the boiler inlet pressure when the unit is determined to be in a steady state, and to divide the working fluid in the boiler into a subcooled liquid state zone and a supercritical state zone based on the boundary temperature; and to establish the mass conservation equation, momentum conservation equation, energy conservation equation and heat transfer equation for the subcooled liquid state zone and the supercritical state zone respectively. The model solving module is used to use the actual operating data of the unit to simultaneously solve the energy conservation equations and heat transfer equations of the subcooled liquid state zone and the supercritical state zone, iteratively solve the heat absorption and length of the subcooled liquid state zone and the supercritical state zone, and use the heat absorption and length of each zone to solve the total heat transfer coefficient of each zone based on the heat transfer equation. State estimation modes are used to discretize the supercooled liquid state partition and the supercritical state partition into multiple spatial nodes, respectively. The temperature of each spatial node in each partition is calculated recursively; using the temperature and density of each spatial node in each partition, a state estimation vector of the unit's initial state is constructed.

17. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-15.

18. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-15.

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