Simulation method and device for drum boiler in subcritical thermal power unit primary frequency modulation analysis

Abstract

The application provides a drum boiler simulation method and device for primary frequency modulation analysis of a subcritical thermal power unit, comprising: dividing a to-be-modeled drum boiler into an evaporation zone and a superheating zone according to a pre-set zoning method; constructing an evaporation zone dynamic model according to volume conservation, mass conservation and energy conservation relations; constructing a superheating zone dynamic model according to an equation of the dynamic characteristics of the superheating zone; coupling the evaporation zone dynamic model and the superheating zone dynamic model to form a drum boiler dynamic model according to the coupling relation of the evaporation zone and the superheating zone; and solving based on the drum boiler dynamic model according to the obtained model input to obtain a simulation result of the main steam parameters of the to-be-modeled drum boiler. The application can more accurately describe the dynamic response characteristics of the main steam parameters of the drum boiler in the primary frequency modulation process of the subcritical thermal power unit, thereby improving the simulation accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system and thermal system analysis, and particularly relates to a simulation method and device for a drum boiler in subcritical thermal power unit primary frequency modulation analysis. BACKGROUND

[0002] The proportion of new energy and power electronic devices in the power system is gradually increasing, and the frequency stability problem of the power grid is increasingly prominent. Thermal power units are gradually transforming into basic support and system regulation power sources. In the new type of power system dominated by new energy, thermal power units will be the main frequency modulation resource on the power supply side. Accurate understanding of the primary frequency modulation capability of thermal power units is of great significance to the frequency safety of the new type of power system.

[0003] The primary frequency modulation capability of subcritical thermal power units is significantly affected by the dynamic characteristics of the drum boiler. However, the boiler model used by the power grid for frequency dynamic analysis cannot accurately reflect the dynamic characteristics of the boiler main steam parameters during primary frequency modulation. The boiler model commonly used in power grid simulation is the IEEE standard boiler model, and the determination method of its heat storage coefficient is relatively complex. At the same time, due to its oversimplification, it cannot guarantee the simulation accuracy under all working conditions. The existing boiler dynamic mathematical models are mostly not suitable for simulation analysis of the primary frequency modulation process, and cannot meet the requirements of model accuracy and simulation rapidity in power grid simulation. SUMMARY

[0004] The present application provides a simulation method and device for a drum boiler in subcritical thermal power unit primary frequency modulation analysis, to solve the defect that the boiler main steam parameter dynamic characteristics during primary frequency modulation cannot be accurately and quickly simulated in the prior art, and to realize the simulation of the drum boiler with accuracy, rapidity and universality.

[0005] The present application provides a simulation method for a drum boiler in subcritical thermal power unit primary frequency modulation analysis, comprising:

[0006] The to-be-modeled drum boiler is divided into an evaporation zone and a superheating zone according to a pre-set partition method;

[0007] An evaporation zone dynamic model is constructed according to the volume conservation, mass conservation and energy conservation relationship; a superheating zone dynamic model is constructed according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat transfer characteristics and flow characteristics;

[0008] The evaporation zone dynamic model and the superheating zone dynamic model are coupled to form a drum boiler dynamic model according to the coupling relationship of the evaporation zone and the superheating zone;

[0009] According to the obtained model input, the drum boiler dynamic model is solved based on the obtained model input, and the simulation result of the main steam parameters of the to-be-modeled drum boiler is obtained.

[0010] The simulation method of the drum boiler for primary frequency modulation analysis of a subcritical thermal power unit according to the present application, the evaporation zone comprises a drum, a downcomer and a water cooling wall; the superheating zone comprises superheaters at different levels, water injection desuperheaters at different levels and a main steam regulating valve.

[0011] The simulation method of the drum boiler for primary frequency modulation analysis of a subcritical thermal power unit according to the present application, the superheating zone dynamic model is constructed according to an equation of dynamic characteristics of the superheating zone, and specifically comprises:

[0012] The superheaters at different levels are simplified as tubular heat exchangers, all the parallel heat exchange tubes included in the superheaters are equivalent to one heat exchange tube, and the tubular heat exchanger is divided into multiple heat exchange units by using a piecewise method;

[0013] The heat exchange characteristic equation of the heat exchange unit is determined according to the energy conservation equation and the heat transfer equation of the working medium and the metal tube wall in the heat exchange unit, and the delay effect caused by the working medium flow;

[0014] Under preset conditions, the flow characteristic equation of the working medium in the superheating zone is obtained according to the mass conservation and momentum conservation equations;

[0015] Under the condition of ignoring the pressure loss and dynamic characteristics of the water injection desuperheating link, the desuperheating water characteristic equation of the water injection desuperheater is obtained according to the mass conservation and energy conservation equations;

[0016] The valve flow characteristic equation of the superheating zone is determined according to the relationship among the main steam pressure, the main steam flow and the comprehensive opening degree of the valve of the superheating zone;

[0017] The superheating zone dynamic model is obtained according to the heat exchange characteristic equation of the heat exchange unit, the flow characteristic equation, the desuperheating water characteristic equation and the valve flow characteristic equation.

[0018] The simulation method of the drum boiler for primary frequency modulation analysis of a subcritical thermal power unit according to the present application, the evaporation zone dynamic model specifically comprises:

[0019]

[0020]

[0021] Wherein, V, ρ and h respectively represent the volume, density and specific enthalpy of the working medium; the subscripts f and g respectively represent saturated water and saturated steam; D fw and D g are the feed water flow entering the drum from the economizer outlet and the saturated steam flow from the drum outlet, respectively; p s is the pressure of the working medium in the evaporation zone; V e is the volume of the evaporation zone; ktp dT s / dp s , T s is the metal wall temperature; k me is the effective metal coefficient of the boiler evaporation zone; c me is the specific heat capacity of the metal wall surface; M me is the mass of the metal wall surface; Q ge is the heat transfer amount of flue gas to the evaporation zone; h we is the specific enthalpy of the feed water at the economizer outlet; and t represents time.

[0022] The application provides a drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power unit, and the coupling relationship between the evaporation zone and the superheating zone comprises:

[0023]

[0024] wherein T sh,i , p sh,i and D sh,i are the temperature, pressure and mass flow of the superheating zone inlet steam respectively; f sh is the resistance coefficient of the superheating zone pipeline.

[0025] The application provides a drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power unit, and the model input comprises the feed water flow entering the drum at the economizer outlet during the primary frequency modulation, the specific enthalpy of the feed water entering the drum and the comprehensive valve opening value; and the simulation result of the main steam parameters of the drum boiler to be modeled comprises the main steam pressure, the main steam flow and the main steam temperature.

[0026] The application further provides a drum boiler simulation device for primary frequency modulation analysis of a subcritical thermal power unit, comprising:

[0027] a partition unit, configured to partition the drum boiler to be modeled into an evaporation zone and a superheating zone according to a pre-set partition method;

[0028] a construction unit, configured to construct an evaporation zone dynamic model according to the volume conservation, mass conservation and energy conservation relationship; and to construct a superheating zone dynamic model according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least comprise heat exchange characteristics and flow characteristics;

[0029] a coupling unit, configured to couple the evaporation zone dynamic model and the superheating zone dynamic model to form a drum boiler dynamic model according to the coupling relationship between the evaporation zone and the superheating zone;

[0030] a simulation unit, configured to solve based on the drum boiler dynamic model according to the obtained model input, and obtain the simulation result of the main steam parameters of the drum boiler to be modeled.

[0031] The application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the simulation method of the drum boiler in the primary frequency modulation analysis of the subcritical thermal power generating unit when executing the program.

[0032] The application further provides a non-transitory computer readable storage medium, which stores a computer program, wherein the computer program implements the simulation method of the drum boiler in the primary frequency modulation analysis of the subcritical thermal power generating unit when executed by a processor.

[0033] The application further provides a computer program product, which comprises a computer program, wherein the computer program implements the simulation method of the drum boiler in the primary frequency modulation analysis of the subcritical thermal power generating unit when executed by a processor.

[0034] The simulation method and device of the drum boiler in the primary frequency modulation analysis of the subcritical thermal power generating unit provided by the application, by dividing the to-be-modeled drum boiler into an evaporation zone and a superheating zone according to a pre-set zoning method; constructing an evaporation zone dynamic model according to the volume conservation, mass conservation and energy conservation relations; constructing a superheating zone dynamic model according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics; coupling the evaporation zone dynamic model and the superheating zone dynamic model to form a drum boiler dynamic model according to the coupling relation of the evaporation zone and the superheating zone; solving based on the drum boiler dynamic model according to the obtained model input, to obtain the simulation result of the main steam parameters of the to-be-modeled drum boiler. The application divides the drum boiler into an evaporation zone and a superheating zone, under the time scale of the primary frequency modulation, focuses on the heat exchange process inside the drum boiler and the flow process of the steam-water working medium when constructing the superheating zone dynamic model, and adopts the lumped parameter method to model when constructing the evaporation zone dynamic model, which can more accurately describe the dynamic response characteristics of the main steam parameters of the drum boiler in the primary frequency modulation process of the subcritical thermal power generating unit, can better balance the accuracy, rapidity and universality of the simulation, and provides an important model basis for accurately mastering the primary frequency modulation capability of the subcritical thermal power generating unit. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0036] Figure 1 is one of the flowcharts of the simulation method of the drum boiler in the primary frequency modulation analysis of the subcritical thermal power generating unit provided by the application.

[0037] Figure 2 is a structure schematic diagram of a drum boiler model of a drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power generating unit provided by the present application;

[0038] Figure 3 is a structure schematic diagram of a drum boiler simulation device for primary frequency modulation analysis of a subcritical thermal power generating unit provided by the present application;

[0039] Figure 4 is a structure schematic diagram of an electronic device provided by the present application. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0041] The present application will be described below with reference to the drawings. Figures 1-2 The present application provides a drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power generating unit, Figure 1 is one of flow schematic diagrams of the drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power generating unit provided by the present application, as shown in the figure, the method comprises the following steps. Figure 1

[0042] Step 110: Dividing the drum boiler to be modeled into an evaporation zone and a superheating zone according to a pre-set zoning method.

[0043] Specifically, the drum boiler to be modeled is divided into zones according to components. The pre-set zoning method comprises the component types included in each zone. In this step, the drum boiler to be modeled is divided into the evaporation zone and the superheating zone from the outlet of the economizer to the outlet of the superheater for modeling analysis, so that the modeling is more accurate and convenient.

[0044] In some embodiments, the evaporation zone comprises a drum, a downcomer and a water wall; and the superheating zone comprises superheaters at different levels, water spray desuperheaters at different levels and a main steam regulating valve.

[0045] Specifically, the evaporation zone of the drum boiler comprises three components, i.e., a drum, a downcomer and a water wall; and the superheating zone of the drum boiler comprises superheaters at different levels, water spray desuperheaters at different levels and a main steam regulating valve.

[0046] Further, in some embodiments, the superheaters at different levels comprise low-temperature superheaters, partition screen superheaters, rear screen superheaters and final-stage superheaters.

[0047] ​Step 120: a dynamic model of the evaporation zone is constructed according to volume conservation, mass conservation and energy conservation relations; a dynamic model of the superheating zone is constructed according to an equation of dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics.

[0048] For the evaporation zone, a lumped parameter model is used to describe the characteristics of the evaporation zone, it is assumed that the physical property parameters of the working medium in the entire evaporation zone are all saturated parameters, and the heat exchange dynamics of the working medium and part of the metal are considered as a whole.

[0049] In the specific implementation process, the volume conservation, mass conservation and energy conservation relations of the evaporation zone are analyzed, and a dynamic mathematical model of the evaporation zone is established.

[0050] In one specific embodiment, the dynamic model of the evaporation zone specifically includes:

[0051]

[0052] In the formula:

[0053]

[0054] Wherein, V, p and h respectively represent the volume, density and specific enthalpy of the working medium; the subscripts f and g respectively represent saturated water and saturated steam; D fw and D g are the feedwater flow rate entering the drum from the economizer outlet and the saturated steam flow rate from the drum outlet, respectively; p s is the pressure of the working medium in the evaporation zone; V e is the volume of the evaporation zone; k tp = dT s / dp s , T s is the metal wall temperature; k me is the effective metal coefficient of the evaporation zone of the boiler; c me is the specific heat capacity of the metal wall surface; M me is the mass of the metal wall surface; Q ge is the heat transfer amount from the flue gas to the evaporation zone; h we is the specific enthalpy of the feedwater from the economizer outlet; and t represents time.

[0055] It should be noted that T s is equal to the saturation temperature of the working medium, and during the primary frequency modulation, the pressure and the corresponding saturation temperature approximately form a linear relationship, so in some embodiments, it is assumed that k tp is constant within the time scale of the primary frequency modulation.

[0056] Further, for the convenience of analysis, in some embodiments, it is assumed that Q ge is constant within the time scale of the primary frequency modulation.

[0057] In the specific implementation process, for the superheating zone, the dynamic heat flow method is used to analyze the heat exchange characteristics of the working medium and the metal pipe wall in the superheating zone, the mass conservation and momentum conservation equations are used to analyze the flow characteristics of the working medium in the superheating zone, the influence of the water injection desuperheater on the thermodynamic parameters of the working medium and the flow characteristics of the valve are considered, and a dynamic mathematical model of the superheating zone is established.

[0058] In some embodiments, the superheating zone dynamic model is constructed according to the equation of the superheating zone dynamic characteristics, and specifically includes:

[0059] Each stage of the superheater is simplified as a tubular heat exchanger, all parallel heat exchange tubes included in the superheater are equivalent to one heat exchange tube, and the tubular heat exchanger is divided into multiple heat exchange units by using the segmentation method.

[0060] According to the energy conservation equation and the heat transfer equation of the working medium and the metal pipe wall in the heat exchange unit, and the delay effect caused by the working medium flow, the heat exchange characteristic equation of the heat exchange unit is determined.

[0061] Under the preset conditions, the flow characteristic equation of the working medium in the superheating zone is obtained according to the mass conservation and momentum conservation equations.

[0062] In the case of ignoring the pressure loss and dynamic characteristics of the water injection desuperheating link, the desuperheating water characteristic equation of the water injection desuperheater is obtained according to the mass conservation and energy conservation equations.

[0063] According to the relationship among the main steam pressure, the main steam flow and the comprehensive opening degree of the valve in the superheating zone, the valve flow characteristic equation of the superheating zone is determined.

[0064] The superheating zone dynamic model is obtained according to the heat exchange characteristic equation of the heat exchange unit, the flow characteristic equation, the desuperheating water characteristic equation and the valve flow characteristic equation.

[0065] Specifically, each stage of the superheater is simplified as a tubular heat exchanger for modeling, all parallel heat exchange tubes are equivalent to one heat exchange tube, the mass flow and the pipeline flow area of the working medium in the equivalent heat exchange tube are the sum of all parallel heat exchange tubes, and the pipeline length is the length of each parallel heat exchange tube. At the same time, if the pipeline length is long, the tubular heat exchanger can be divided into multiple heat exchange units for analysis by using the segmentation idea.

[0066] The energy conservation equation of the working medium and the metal pipe wall in the heat exchange unit is written, the dynamic heat flow method is used for equation solving, the delay effect caused by the fluid flow is considered, and the heat exchange characteristic equation of the heat exchange unit is determined.

[0067] In one specific embodiment, the heat exchange characteristic equation of the superheating zone heat exchange unit includes:

[0068]

[0069] where T ci and T co are the working fluid temperatures at the inlet and outlet of the heat exchange unit, respectively; T m is the metal wall temperature of the heat exchange unit; a c = k c A c / G c ; G c is the heat capacity flow of the working fluid in the tube, defined as the product of the mass flow and the constant-pressure specific heat capacity; k c is the heat transfer coefficient between the working fluid in the tube and the metal of the tube wall; A c is the heat exchange area between the working fluid in the tube and the metal of the tube wall; Q gm is the heat transfer amount from the flue gas to the metal tube wall in the heat exchange unit, which is assumed to be constant during the primary frequency modulation; R gm is the heat transfer thermal resistance between the working fluid in the tube and the metal of the tube wall of the heat exchange unit, τ c = R c C c , C m is the time constant of the heat exchange unit during the heat exchange process, C m is the heat capacity of the metal of the tube wall in the heat exchange unit; T m0 is the initial wall temperature of the heat exchange unit; t represents time; Δt = l / w, where l is the length of the heat exchange unit and w is the flow rate of the working fluid in the tube.

[0070] Under preset conditions, the flow characteristics equation of the working fluid in the superheated zone can be obtained by analyzing the mass conservation and momentum conservation equations. It should be noted that the preset conditions are that the flow resistance of the working fluid is assumed to be concentrated at the outlet of the heat exchange unit.

[0071] In one embodiment, the flow characteristics equation includes:

[0072]

[0073]

[0074] where F c is the flow area of the heat exchanger tube; p c is the density of the working fluid in the heat exchange unit; p ci and p co are the pressures of the working fluid at the inlet and outlet of the heat exchange unit, respectively; D ci and D co are the mass flow rates of the working fluid at the inlet and outlet of the heat exchange unit, respectively; and f sh is the resistance coefficient of the heat exchanger tube in the superheated zone.

[0075] For the water spray desuperheater, the pressure loss and dynamic characteristics of the water spray desuperheating link are ignored. Considering the influence of the water spray desuperheating link, a desuperheating water characteristic equation is obtained.

[0076] In one specific embodiment, the desuperheating water characteristic equation comprises:

[0077]

[0078] wherein D sa,o and h sa,o are the mass flow rate and specific enthalpy of the steam at the outlet of the desuperheater; D sa,i and h sa,i are the mass flow rate and specific enthalpy of the steam at the inlet of the desuperheater; D sw is the mass flow rate of the desuperheating water at each stage; and h sw is the specific enthalpy of the desuperheating water.

[0079] Considering the valve flow characteristics, it is considered that the valve flow function of the unit is designed reasonably and can better realize the linear control of the total valve position command on the main steam flow. A valve flow characteristic equation is obtained.

[0080] In one specific embodiment, the valve flow characteristic equation comprises:

[0081] D st = kv·cv·p st

[0082] wherein p st and D st are the main steam pressure and the main steam flow rate; cv is the total valve opening; and kv is the valve flow coefficient.

[0083] The heat exchange characteristic equation, the flow characteristic equation, the desuperheating water characteristic equation, and the valve flow characteristic equation of the heat exchange unit together constitute a superheating zone dynamic model.

[0084] Step 130: According to the coupling relationship of the evaporation zone and the superheating zone, the evaporation zone dynamic model and the superheating zone dynamic model are coupled to constitute a drum boiler dynamic model;

[0085] In some embodiments, the coupling relationship of the evaporation zone and the superheating zone comprises:

[0086]

[0087] wherein T sh,i , p sh,i and D sh,i are the temperature, pressure and mass flow rate of the steam at the inlet of the superheating zone; and f sh is the resistance coefficient of the superheating zone pipeline.

[0088] Step 140: according to the obtained model input, solving based on the drum boiler dynamic model, to obtain the simulation result of the main steam parameter of the to-be-modeled drum boiler.

[0089] After obtaining the overall drum boiler dynamic model, the main steam parameter simulation is performed by using the drum boiler dynamic model.

[0090] It can be understood that the main steam parameter includes the main steam pressure, the main steam flow and the main steam temperature.

[0091] In some embodiments, the model input includes the feed water flow entering the drum at the economizer outlet during the primary frequency modulation, the feed water specific enthalpy entering the drum and the comprehensive valve opening value; and the simulation result of the main steam parameter of the to-be-modeled drum boiler includes the main steam pressure, the main steam flow and the main steam temperature.

[0092] Specifically, in the simulation process, the drum boiler dynamic model input is the feed water flow entering the drum at the economizer outlet during the primary frequency modulation, the feed water specific enthalpy entering the drum and the comprehensive valve opening value, and the dynamic simulation result of the main steam parameter of the drum boiler during the primary frequency modulation can be obtained by solving the drum boiler dynamic model.

[0093] The simulation method of the drum boiler for the primary frequency modulation analysis of the subcritical thermal power unit provided by the present application divides the to-be-modeled drum boiler into an evaporation zone and a superheating zone according to a pre-set partition method; an evaporation zone dynamic model is constructed according to the volume conservation, the mass conservation and the energy conservation relationship; a superheating zone dynamic model is constructed according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include the heat exchange characteristics and the flow characteristics; the evaporation zone dynamic model and the superheating zone dynamic model are coupled to form a drum boiler dynamic model according to the coupling relationship of the evaporation zone and the superheating zone; and the simulation result of the main steam parameter of the to-be-modeled drum boiler is obtained by solving based on the drum boiler dynamic model according to the obtained model input. The present application divides the drum boiler into the evaporation zone and the superheating zone, focuses on the heat exchange process inside the drum boiler and the flow process of the steam-water working medium when constructing the superheating zone dynamic model under the time scale of the primary frequency modulation, and adopts the lumped parameter method to model when constructing the evaporation zone dynamic model, which can more accurately describe the dynamic response characteristics of the main steam parameter of the drum boiler in the primary frequency modulation process of the subcritical thermal power unit, can better balance the accuracy, the rapidity and the universality of the simulation, and provides an important model basis for accurately mastering the primary frequency modulation capability of the subcritical thermal power unit.

[0094] The simulation device of the drum boiler for the primary frequency modulation analysis of the subcritical thermal power unit provided by the present application is described below, and the simulation device of the drum boiler for the primary frequency modulation analysis of the subcritical thermal power unit described below can be correspondingly referred to the simulation method of the drum boiler for the primary frequency modulation analysis of the subcritical thermal power unit described above. Figure 3It is the structure schematic view of the simulation device for subcritical thermal power unit primary frequency modulation analysis of the drum boiler provided by the application, as shown in the figure, the device comprises: Figure 3

[0095] The partition unit 310 is used for dividing the drum boiler to be modeled into the evaporation zone and the superheating zone according to a pre-set partition method.

[0096] The construction unit 320 is used for constructing the evaporation zone dynamic model according to the volume conservation, the mass conservation and the energy conservation relationship; the superheating zone dynamic model is constructed according to the equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include the heat exchange characteristics and the flow characteristics.

[0097] The coupling unit 330 is used for coupling the evaporation zone dynamic model and the superheating zone dynamic model to constitute the drum boiler dynamic model according to the coupling relationship of the evaporation zone and the superheating zone.

[0098] The simulation unit 340 is used for solving based on the drum boiler dynamic model according to the obtained model input, to obtain the simulation result of the main steam parameter of the drum boiler to be modeled.

[0099] According to the simulation device for subcritical thermal power unit primary frequency modulation analysis of the drum boiler provided by the application, the evaporation zone comprises the drum, the downcomer and the water cooling wall; the superheating zone comprises the superheater, the water spray desuperheater and the main steam regulating valve.

[0100] According to the simulation device for subcritical thermal power unit primary frequency modulation analysis of the drum boiler provided by the application, the superheating zone dynamic model is constructed according to the equation of the dynamic characteristics of the superheating zone, and specifically comprises:

[0101] The superheater is simplified as a tubular heat exchanger, all the parallel heat exchange tubes included in the superheater are equivalent to a heat exchange tube, and the tubular heat exchanger is divided into multiple heat exchange units by using the sectional method.

[0102] According to the energy conservation equation and the heat transfer equation of the working medium and the metal tube wall in the heat exchange unit, and the delay effect caused by the working medium flow, the heat exchange characteristic equation of the heat exchange unit is determined.

[0103] Under the preset condition, the flow characteristic equation of the working medium in the superheating zone is obtained according to the mass conservation and momentum conservation equations;

[0104] Under the condition of ignoring the pressure loss and the dynamic characteristics of the water spray desuperheating link, the desuperheating water characteristic equation of the water spray desuperheater is obtained according to the mass conservation and energy conservation equations.

[0105] According to the relationship among the main steam pressure, the main steam flow and the comprehensive opening degree of the valve of the superheating zone, the valve flow characteristic equation of the superheating zone is determined.​

[0106] The superheating zone dynamic model is obtained according to the heat exchange characteristic equation of the heat exchange unit, the flow characteristic equation, the desuperheating water characteristic equation and the valve flow characteristic equation.

[0107] According to the subcritical thermal power generating unit primary frequency modulation analysis steam drum boiler simulation device provided by the application, the evaporation zone dynamic model specifically comprises:

[0108]

[0109]

[0110] Wherein, V, ρ and h respectively represent the volume, density and specific enthalpy of the working medium; the subscripts f and g respectively represent saturated water and saturated steam; D fw and D g are the feed water flow rate entering the steam drum from the economizer outlet and the saturated steam flow rate from the steam drum outlet; p s is the pressure of the evaporation zone working medium; V e is the evaporation zone volume; k tp = dT s / dp s , T s is the metal wall temperature; k me is the effective metal coefficient of the boiler evaporation zone; c me is the specific heat capacity of the metal wall surface; M me is the mass of the metal wall surface; Q ge is the heat transfer amount from the flue gas to the evaporation zone; h we is the specific enthalpy of the feed water from the economizer outlet; and t represents time.

[0111] According to the subcritical thermal power generating unit primary frequency modulation analysis steam drum boiler simulation device provided by the application, the coupling relationship of the evaporation zone and the superheating zone comprises:

[0112]

[0113] Wherein, T sh,i , p sh,i and D sh,i are the temperature, pressure and mass flow rate of the steam entering the superheating zone; f sh is the resistance coefficient of the superheating zone pipeline.

[0114] According to the subcritical thermal power generating unit primary frequency modulation analysis steam drum boiler simulation device provided by the application, the model input comprises the feed water flow rate entering the steam drum from the economizer outlet during the primary frequency modulation, the specific enthalpy of the feed water entering the steam drum and the comprehensive valve opening degree value; and the simulation result of the main steam parameters of the to-be-modeled steam drum boiler comprises the main steam pressure, the main steam flow rate and the main steam temperature.

[0115] The application provides a drum boiler simulation device for primary frequency modulation analysis of a subcritical thermal power unit, which comprises the following steps: a to-be-modeled drum boiler is divided into an evaporation zone and a superheating zone according to a pre-set partition method; an evaporation zone dynamic model is constructed according to the volume conservation, mass conservation and energy conservation relationship; a superheating zone dynamic model is constructed according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics; the evaporation zone dynamic model and the superheating zone dynamic model are coupled to form a drum boiler dynamic model according to the coupling relationship between the evaporation zone and the superheating zone; and a simulation result of the main steam parameters of the to-be-modeled drum boiler is obtained by solving based on the drum boiler dynamic model according to the obtained model input. The drum boiler is divided into the evaporation zone and the superheating zone, the heat exchange process inside the drum boiler and the flow process of the steam-water working medium are focused on when the superheating zone dynamic model is constructed under the time scale of primary frequency modulation, the lumped parameter method is used for modeling when the evaporation zone dynamic model is constructed, the dynamic response characteristics of the main steam parameters of the drum boiler in the primary frequency modulation process of the subcritical thermal power unit can be accurately described, the accuracy, rapidity and universality of the simulation can be well balanced, and an important model basis for accurately mastering the primary frequency modulation capability of the subcritical thermal power unit is provided.

[0116] Figure 4 An example of a schematic diagram of a physical structure of an electronic device is shown in FIG. 1. Figure 4 As shown in FIG. 1, the electronic device can include a processor 410, a communications interface 420, a memory 430, and a communications bus 440, wherein the processor 410, the communications interface 420, and the memory 430 can communicate with each other through the communications bus 440. The processor 410 can invoke a logical instruction in the memory 430 to execute a drum boiler simulation method for primary frequency modulation analysis of a subcritical thermal power unit, which comprises the following steps: a to-be-modeled drum boiler is divided into an evaporation zone and a superheating zone according to a pre-set partition method; an evaporation zone dynamic model is constructed according to the volume conservation, mass conservation and energy conservation relationship; a superheating zone dynamic model is constructed according to an equation of the dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics; the evaporation zone dynamic model and the superheating zone dynamic model are coupled to form a drum boiler dynamic model according to the coupling relationship between the evaporation zone and the superheating zone; and a simulation result of the main steam parameters of the to-be-modeled drum boiler is obtained by solving based on the drum boiler dynamic model according to the obtained model input.

[0117] Further, the logic instructions in the memory 430 described above can be implemented in the form of software functional units and sold or used as standalone products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk, and various media that can store program codes.

[0118] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to execute the simulation method of the drum boiler for primary frequency modulation analysis of the subcritical thermal power generating unit provided by the above-mentioned methods. The method comprises: dividing a to-be-modeled drum boiler into an evaporation zone and a superheating zone according to a pre-set zoning method; constructing an evaporation zone dynamic model according to volume conservation, mass conservation and energy conservation relationships; constructing a superheating zone dynamic model according to an equation of dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics; coupling the evaporation zone dynamic model and the superheating zone dynamic model to form a drum boiler dynamic model according to a coupling relationship between the evaporation zone and the superheating zone; and solving based on the drum boiler dynamic model according to obtained model inputs to obtain a simulation result of main steam parameters of the to-be-modeled drum boiler.

[0119] In another aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the simulation method of the drum boiler for primary frequency modulation analysis of the subcritical thermal power generating unit provided by the above-mentioned methods. The method comprises: dividing a to-be-modeled drum boiler into an evaporation zone and a superheating zone according to a pre-set zoning method; constructing an evaporation zone dynamic model according to volume conservation, mass conservation and energy conservation relationships; constructing a superheating zone dynamic model according to an equation of dynamic characteristics of the superheating zone; the dynamic characteristics at least include heat exchange characteristics and flow characteristics; coupling the evaporation zone dynamic model and the superheating zone dynamic model to form a drum boiler dynamic model according to a coupling relationship between the evaporation zone and the superheating zone; and solving based on the drum boiler dynamic model according to obtained model inputs to obtain a simulation result of main steam parameters of the to-be-modeled drum boiler.

[0120] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0121] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0122] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A simulation method for primary frequency regulation analysis of subcritical thermal power units using a steam drum boiler, characterized in that, include: The boiler drum to be modeled is divided into an evaporation zone and a superheating zone according to the pre-set zoning method. A dynamic model of the evaporation zone is constructed based on the conservation of volume, mass, and energy; a dynamic model of the superheated zone is constructed based on the equations of the dynamic characteristics of the superheated zone; the dynamic characteristics include at least heat transfer characteristics and flow characteristics; Based on the connection relationship between the evaporation zone and the superheated zone, the dynamic model of the evaporation zone and the dynamic model of the superheated zone are coupled to form a dynamic model of the steam drum boiler; Based on the obtained model input, the simulation results of the main steam parameters of the boiler to be modeled are obtained by solving the dynamic model of the boiler drum. The evaporation zone includes a steam drum, downcomers, and water-cooled walls; The superheated zone includes superheaters of various stages, water spray desuperheaters of various stages, and main steam regulating valves; The connection relationship between the evaporation zone and the superheated zone includes: Among them, T sh,i p sh,i and D sh,i These are the temperature, pressure, and mass flow rate of the steam at the inlet of the superheated zone; f sh T is the resistance coefficient of the superheated zone pipeline. s For the metal wall temperature, p s D is the pressure of the working fluid in the evaporation zone. g ρ is the saturated steam flow rate at the steam drum outlet. g This is the density of saturated vapor.

2. The simulation method for primary frequency regulation analysis of subcritical thermal power units using a steam drum boiler according to claim 1, characterized in that, The process of constructing a dynamic model of the superheated zone based on the equations governing the dynamic characteristics of the superheated zone specifically includes: The superheaters at each stage are simplified to tubular heat exchangers, and all parallel heat exchange tubes included in the superheater are equivalent to a single heat exchange tube. The tubular heat exchanger is divided into multiple heat exchange units using a segmentation method. Based on the energy conservation equation and heat transfer equation of the working fluid and metal tube wall in the heat exchange unit, as well as the delay effect caused by the flow of the working fluid, the heat transfer characteristic equation of the heat exchange unit is determined. Under preset conditions, the flow characteristic equation of the working fluid in the superheated zone is obtained based on the equations of mass conservation and momentum conservation. Ignoring the pressure loss and dynamic characteristics of the water spray desuperheating process, the desuperheating water characteristic equation of the water spray desuperheater is obtained based on the mass conservation and energy conservation equations. Based on the relationship between the main steam pressure, main steam flow rate, and overall valve opening in the superheated zone, the valve flow characteristic equation for the superheated zone is determined. The dynamic model of the superheated zone is obtained based on the heat transfer characteristic equation of the heat exchange unit, the flow characteristic equation, the desuperheating water characteristic equation, and the valve flow characteristic equation.

3. The simulation method for primary frequency regulation analysis of subcritical thermal power units using a steam drum boiler according to claim 1, characterized in that, The dynamic model of the evaporation zone specifically includes: Where V, ρ, and h represent the volume, density, and specific enthalpy of the working fluid, respectively; the subscripts f and g represent saturated water and saturated vapor, respectively; D fw V is the feedwater flow rate entering the steam drum from the economizer outlet. e k is the volume of the evaporation zone. tp =dT s / dp s ;k me c is the effective metal coefficient of the boiler evaporation zone; me M is the specific heat capacity of the metal wall surface; me Q represents the mass of the metal wall surface. ge For the heat transfer of flue gas to the evaporation zone; h we t represents the specific enthalpy of the feedwater at the economizer outlet; t represents time.

4. The simulation method for primary frequency regulation analysis of subcritical thermal power units using a steam drum boiler according to claim 1, characterized in that, The model inputs include the feedwater flow rate from the economizer outlet into the steam drum, the feedwater specific enthalpy into the steam drum, and the overall valve opening value during the primary frequency regulation period; the simulation results of the main steam parameters of the steam drum boiler to be modeled include the main steam pressure, main steam flow rate, and main steam temperature.

5. A simulation device for primary frequency regulation analysis of subcritical thermal power units using a steam drum boiler, characterized in that, include: The partitioning unit is used to divide the boiler drum to be modeled into an evaporation zone and a superheating zone according to a pre-set partitioning method. A construction unit is used to construct a dynamic model of the evaporation zone based on the conservation of volume, mass, and energy; and to construct a dynamic model of the superheated zone based on the equations of the dynamic characteristics of the superheated zone; the dynamic characteristics include at least heat transfer characteristics and flow characteristics. A coupling unit is used to couple the dynamic model of the evaporation zone and the dynamic model of the superheated zone to form a dynamic model of the steam drum boiler based on the connection relationship between the evaporation zone and the superheated zone. The simulation unit is used to solve the simulation results of the main steam parameters of the steam drum boiler to be modeled based on the acquired model input and the dynamic model of the steam drum boiler. The evaporation zone includes a steam drum, downcomers, and water-cooled walls; The superheated zone includes superheaters of various stages, water spray desuperheaters of various stages, and main steam regulating valves; The connection relationship between the evaporation zone and the superheated zone includes: Among them, T sh,i p sh,i and D sh,i These are the temperature, pressure, and mass flow rate of the steam at the inlet of the superheated zone; f sh T is the resistance coefficient of the superheated zone pipeline. s For the metal wall temperature, p s D is the pressure of the working fluid in the evaporation zone. g ρ is the saturated steam flow rate at the steam drum outlet. g This is the density of saturated vapor.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the boiler simulation method for primary frequency regulation analysis of subcritical thermal power units as described in any one of claims 1 to 4.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the boiler simulation method for primary frequency regulation analysis of subcritical thermal power units as described in any one of claims 1 to 4.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the boiler simulation method for primary frequency regulation analysis of subcritical thermal power units as described in any one of claims 1 to 4.

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