A thermal flow modeling-based energy storage characterization method and system for thermal power generating units

Abstract

The application discloses a thermal energy storage characterization method and system for a thermal power generating unit based on heat flow modeling, and relates to the technical field of power systems.The method comprises the following steps: based on preset superheater working conditions, establishing a superheater energy flow model corresponding to the thermal power generating unit; determining the heat capacity flow parameters of each superheater in the superheater energy flow model; based on the heat capacity flow parameters of each superheater, calculating the equivalent thermal resistance data corresponding to each superheater; according to the heat capacity flow parameters of each superheater and the superheater energy flow model, determining the tube wall temperature of each superheater in the superheater energy flow model and the input temperature of each superheater; inputting the state variables into preset heat transfer state equations and preset heat transfer output equations respectively to obtain the output thermal energy of each superheater through simultaneous calculation; and based on the output thermal energy of each superheater, calculating the output thermal energy of the thermal power generating unit.The application can accurately characterize the real-time thermal storage capacity and real-time output of the boiler side of the thermal power generating unit.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method and system for characterizing the energy storage of thermal power units based on heat flow modeling. Background Technology

[0002] The development of renewable energy will play a crucial role in building new power systems, which is of great significance to China's carbon peaking and carbon neutrality strategies. With the development of sustainable energy systems over the past few decades, China's total installed capacity of wind and solar power will exceed 1.2 billion kilowatts by 2030. However, the high penetration rate of renewable energy, such as wind and solar power plants replacing traditional thermal energy, has significantly reduced frequency control capabilities. Furthermore, the intermittency and randomness of wind and solar power pose significant challenges to frequency stability, leading to increased frequency disturbances in the power grid. Therefore, frequency control, by minimizing the imbalance between load and generation and correcting system frequency deviations, is receiving increasing attention.

[0003] Frequency regulation performance is a crucial factor affecting power grid stability and security. The goal of frequency control is to maintain the frequency as close as possible to the rated value (50Hz in China) to avoid unnecessary low-frequency load shedding, low-frequency generator tripping, generator damage, and low-frequency cascading events. When power supply suddenly becomes insufficient, the frequency drops rapidly, reaching its minimum within 10 seconds. During this period, only primary frequency regulation can provide emergency frequency control services to suppress the system frequency drop. In summary, when demand deviates from generator supply, primary frequency regulation is the essential effect of the power system in suppressing frequency deviation. The generator side and the demand side are the two main components affecting primary frequency regulation capability.

[0004] Research on primary frequency control based on boiler energy storage has not yet seen further development. Dynamic simulation models are widely used to assess the impact of operational schemes and technological changes on components. Over the past few decades, various simulation tools have been further developed and applied to the modeling of conventional thermal power plants. Previous researchers dynamically modeled a simplified control system of a coal-fired power plant to assess the integration of additional thermal storage and possible load gradient changes. Since the assessment of the impact of load changes on components depends more on the outcome of meeting external demands, another application of dynamic simulation is to predict component behavior by modifying components based on simulation results. The transfer of modifications tested in the simulation model to the real plant is closely related to the daily operation of the plant. Considering all uncertainties that occur during data collection, model implementation, verification, and result transfer, this approach requires high model accuracy. Time-varying effects on real power plant behavior, such as fuel variations and mill degradation, are of paramount importance. These are models that take all components into account. Research on turbine models and governor system models, which play a crucial role in primary frequency regulation during dynamic processes, has been extensive. The turbine single decoupling model has high accuracy in primary frequency regulation. Therefore, it is essential to study a high-precision, linear boiler superheater model and predict its primary frequency regulation capability. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for characterizing the energy storage of thermal power units based on heat flow modeling, so as to accurately characterize the real-time heat storage capacity and real-time output of the boiler side of the thermal power unit.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for characterizing the energy storage of thermal power units based on heat flow modeling, wherein the thermal power unit includes multiple superheaters connected in sequence, and the method for characterizing the energy storage of thermal power units includes:

[0008] Based on the preset superheater operating conditions, a superheater energy flow model corresponding to the thermal power unit is established.

[0009] Determine the heat capacity and flow rate parameters of each section of the superheater in the superheater energy flow model;

[0010] Based on the heat capacity flow parameters of each superheater segment, calculate the equivalent thermal resistance data corresponding to each superheater segment.

[0011] Based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model, the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model are determined; the tube wall temperatures of multiple superheaters constitute state variables;

[0012] The state variables are input into the preset heat transfer state equation and the preset heat transfer output equation respectively, and the output heat energy of each superheater segment is calculated simultaneously. The preset heat transfer state equation is determined based on the equivalent thermal resistance data of each superheater segment and the input temperature of each superheater segment. The preset heat transfer output equation is determined based on the equivalent thermal resistance data of each superheater segment, the tube wall temperature of each superheater segment, and the input temperature of each superheater segment.

[0013] The output thermal energy of the thermal power unit is calculated based on the output thermal energy of each superheater segment.

[0014] Optionally, the thermal power unit includes a primary superheater, a screen-type superheater, and a final superheater connected in sequence; the equivalent thermal resistance data corresponding to each superheater segment includes the equivalent thermal resistance data of the cold fluid in the superheater and the equivalent thermal resistance data of the hot fluid in the superheater; the input temperature corresponding to each superheater segment includes the input temperature of the hot fluid in the superheater and the input temperature of the cold fluid in the superheater.

[0015] The preset heat transfer state equation is:

[0016]

[0017] in, x represents a state variable, x = [T] w1 T w2 T w3 ] T T wi c represents the tube wall temperature of the i-th superheater segment. p M represents the specific heat capacity of the metal tube wall. i R represents the metal mass of the i-th superheater segment. ih R represents the equivalent thermal resistance data of the hot fluid in the i-th segment of the superheater. ic T represents the equivalent thermal resistance data of the cold fluid in the i-th segment of the superheater. hi，in T represents the input temperature of the hot fluid in the i-th segment of the superheater. ci，in Let u represent the input temperature of the cold fluid in the i-th superheater segment, and let u represent the hidden variable; i∈[1,2,3], the first superheater segment is the primary superheater, the second superheater segment is the screen-type superheater, and the third superheater segment is the final superheater.

[0018] Optionally, the preset heat transfer output equation is:

[0019] y = g(x, u, t);

[0020] Where y = Cx + D,

[0021]

[0022] y represents the total heat storage of the thermal power unit, y = [Q1, Q2, Q3, Q4, Q5, Q6] T , Q1 represents the heat exchange of the cold fluid in the primary superheater, i.e., the output heat energy of the primary superheater; Q2 represents the heat exchange of the cold fluid in the screen superheater, i.e., the output heat energy of the screen superheater; Q3 represents the heat exchange of the cold fluid in the final superheater, i.e., the output heat energy of the final superheater; Q4 represents the heat storage of the metal in the primary superheater; Q5 represents the heat storage of the metal in the screen superheater; and Q6 represents the heat storage of the metal in the final superheater.

[0023] Optionally, establishing the superheater energy flow model corresponding to the thermal power unit based on preset superheater operating conditions specifically includes:

[0024] Based on the basic data of the thermal power unit, a physical model of the superheater is established. The basic data of the thermal power unit includes the number and connection sequence of the superheaters in the thermal power unit, the specific heat capacity of the metal tube wall, the metal mass of each superheater section, the thermal conductivity of the hot fluid inside the metal tube wall, and the thermal conductivity of the cold fluid inside the metal tube wall.

[0025] Based on the preset boiler superheater operating conditions and the superheater physical model, a superheater energy flow model corresponding to the thermal power unit is established.

[0026] Optionally, the heat capacity flow parameters of each superheater segment in the superheater energy flow model are determined, specifically including:

[0027] For each section of the superheater in the superheater energy flow model, obtain the cold fluid flow rate and the hot fluid flow rate in the superheater.

[0028] Based on the heat exchanger energy flow model, the specific heat capacity of the metal tube wall is obtained;

[0029] Calculate the cold fluid heat capacity flow rate based on the cold fluid flow rate and the specific heat capacity of the metal pipe wall;

[0030] The heat capacity flow rate of the hot fluid is calculated based on the flow rate of the hot fluid and the specific heat capacity of the metal tube wall; the heat capacity flow rate of the cold fluid and the heat capacity flow rate of the hot fluid constitute the heat capacity flow rate parameters of the superheater.

[0031] Optionally, based on the heat capacity flow rate parameters of each superheater segment, the equivalent thermal resistance data corresponding to each superheater segment is calculated, specifically including:

[0032] Based on the heat exchanger energy flow model, the thermal conductivity of the hot fluid inside the metal pipe wall and the thermal conductivity of the cold fluid inside the metal pipe wall are obtained.

[0033] For each section of the superheater in the superheater energy flow model, the equivalent cold fluid thermal resistance is calculated based on the cold fluid heat capacity flow and the thermal conductivity of the cold fluid inside the metal tube wall, and the equivalent hot fluid thermal resistance is calculated based on the hot fluid heat capacity flow and the thermal conductivity of the hot fluid inside the metal tube wall; the equivalent cold fluid thermal resistance and the equivalent hot fluid thermal resistance constitute the equivalent thermal resistance data of the superheater.

[0034] Optionally, the output thermal energy of the thermal power unit is calculated based on the output thermal energy of each superheater section, specifically including:

[0035] Obtain the input thermal energy of the thermal power unit;

[0036] The input thermal energy of the thermal power unit and the output thermal energy of each section of the superheater are added together to obtain the output thermal energy of the thermal power unit.

[0037] To achieve the above objectives, the present invention also provides the following technical solutions:

[0038] A thermal power unit energy storage characterization system based on heat flow modeling, wherein the thermal power unit includes multiple superheaters connected in sequence, and the thermal power unit energy storage characterization system includes:

[0039] The model building module is used to establish a superheater energy flow model corresponding to the thermal power unit based on preset superheater operating conditions.

[0040] The parameter determination module is used to determine the heat capacity flow parameters of each section of the superheater in the superheater energy flow model.

[0041] The equivalent thermal resistance calculation module is used to calculate the equivalent thermal resistance data corresponding to each segment of the superheater based on the heat capacity flow parameters of each segment of the superheater.

[0042] The temperature determination module is used to determine the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model; the tube wall temperatures of multiple superheaters constitute state variables;

[0043] The output heat energy calculation module is used to input the state variables into the preset heat transfer state equation and the preset heat transfer output equation respectively, so as to calculate the output heat energy of each superheater segment simultaneously; the preset heat transfer state equation is determined based on the equivalent thermal resistance data of each superheater segment and the input temperature of each superheater segment; the preset heat transfer output equation is determined based on the equivalent thermal resistance data of each superheater segment, the tube wall temperature of each superheater segment, and the input temperature of each superheater segment.

[0044] The unit output thermal energy determination module is used to calculate the output thermal energy of the thermal power unit based on the output thermal energy of each section of the superheater.

[0045] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0046] This invention discloses a method and system for characterizing the energy storage of thermal power units based on heat flow modeling. It establishes an energy flow model for the superheater corresponding to the thermal power unit. Based on this model, the heat capacity flow parameters, equivalent thermal resistance data, tube wall temperature, and input temperature of each superheater section are determined. A preset heat transfer state equation is determined based on the equivalent thermal resistance data and input temperature of each superheater section. Similarly, a preset heat transfer output equation is determined based on the equivalent thermal resistance data, tube wall temperature, and input temperature of each superheater section. Then, using the preset heat transfer state equation and preset heat transfer output equation, the accurate output heat energy of each superheater section is calculated in real time, thereby obtaining the accurate and real-time output heat energy of the thermal power unit, thus precisely characterizing the real-time heat storage capacity and real-time power output of the boiler side of the thermal power unit. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating the energy storage characterization method for thermal power units based on heat flow modeling according to the present invention.

[0049] Figure 2 For the physical model of the superheater;

[0050] Figure 3 For superheater energy flow model;

[0051] Figure 4 A comparison chart of the thermal energy stored in the working fluid under different operating conditions;

[0052] Figure 5 This is a schematic diagram of the structure of the thermal power unit energy storage characterization system based on heat flow modeling according to the present invention.

[0053] Symbol explanation:

[0054] 1- Primary superheater, 2- Screen-type superheater, 3- Final superheater. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The purpose of this invention is to provide a method and system for characterizing the energy storage of thermal power units based on heat flow modeling, and a method for modeling the heat flow of superheaters and reheaters based on dynamic energy flow method, so as to accurately characterize the heat storage capacity and real-time output of thermal power units on the boiler side in real time.

[0057] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] Example 1

[0059] This embodiment provides a method for characterizing the energy storage of thermal power units based on heat flow modeling. The thermal power unit includes multiple superheaters connected in sequence. Specifically, the thermal power unit includes a primary superheater, a screen-type superheater, and a final superheater connected in sequence.

[0060] like Figure 1 As shown, the energy storage characterization methods for thermal power units include:

[0061] Step 100: Based on the preset superheater operating conditions, establish the superheater energy flow model corresponding to the thermal power unit.

[0062] Step 100 specifically includes:

[0063] 1) Based on the basic data of the thermal power unit, establish a physical model of the superheater. The basic data of the thermal power unit includes the number and connection sequence of superheaters in the unit, the specific heat capacity of the metal tube wall, the metal mass of each superheater section, the thermal conductivity of the hot fluid inside the metal tube wall, the thermal conductivity of the cold fluid inside the metal tube wall, and the length of each superheater section. In practical applications, the above basic data can be determined according to the boiler manual.

[0064] like Figure 2 As shown, the input end of the primary superheater 1 is connected to the steam-water separator, the output end of the primary superheater is connected to the input end of the screen-type superheater 2, and the output end of the screen-type superheater 2 is connected to the input end of the final stage superheater; and the pressure at the input end of the primary superheater is p. s The unit is MPa; the pressure at the output end of the final stage superheater is p. mA feedwater pump is installed between the primary superheater 1 and the screen-type superheater 2, with feedwater flow rates of D1 and D2 respectively. A feedwater pump is installed between the screen-type superheater 2 and the final superheater 3, with feedwater flow rates of D3 and D4 respectively. The unit of feedwater flow rate is t / h.

[0065] 2) Based on the preset boiler superheater operating conditions and the superheater physical model, establish the superheater energy flow model corresponding to the thermal power unit, such as... Figure 3 As shown.

[0066] Specifically, when evaluating the thermal storage performance and output capacity of a boiler, the energy stored on the metal wall of the superheater plays a crucial role in this process. Therefore, assumptions can be made to the model, namely, setting preset boiler superheater operating conditions, as follows:

[0067] 21) Flue gas flow rate and temperature remain constant over short timescales.

[0068] 22) The energy stored in the boiler is mainly from the superheated components; other components such as the economizer and steam-water separator can be ignored.

[0069] 23) The parallel tubes of the overheated components are equivalent to a heat exchanger with a certain length and thickness.

[0070] 24) Assume that the four water pumps are a water supply process with certain pressure, temperature and flow rate.

[0071] in addition, Figure 3 In the middle, T ci,out This represents the outlet temperature of the cold fluid in the i-th segment of the superheater, in K.

[0072] Step 200: Determine the heat capacity flow rate parameters of each superheater segment in the superheater energy flow model.

[0073] Step 200 specifically includes:

[0074] 1) For each superheater segment in the superheater energy flow model, obtain the cold fluid flow rate and hot fluid flow rate in the superheater. Specifically, the cold fluid flow rate and hot fluid flow rate in the superheater are acquired through the DCS components of the thermal power unit.

[0075] 2) Based on the heat exchanger energy flow model, obtain the specific heat capacity c of the metal tube wall. p .

[0076] 3) Calculate the cold fluid heat capacity flow rate based on the cold fluid flow rate and the specific heat capacity of the metal tube wall; calculate the hot fluid heat capacity flow rate based on the hot fluid flow rate and the specific heat capacity of the metal tube wall. The cold fluid heat capacity flow rate and the hot fluid heat capacity flow rate constitute the heat capacity flow rate parameters of the superheater. That is, the cold fluid heat capacity flow rate and the hot fluid heat capacity flow rate are calculated using the following formulas:

[0077]

[0078] Among them, G i,h This represents the heat capacity flow rate of the hot fluid in the i-th segment of the superheater, in kJ / K·s, G. i,c D represents the heat capacity flow of the cold fluid in the i-th segment of the superheater, in kJ / K·s. i,c D represents the flow rate of the cooling fluid in the i-th superheater segment, in t / h. i,h This represents the flow rate of the hot fluid in the i-th superheater segment, in t / h.

[0079] Step 300: Calculate the equivalent thermal resistance data for each segment of the superheater based on the heat capacity flow rate parameters of each segment of the superheater.

[0080] Step 300 specifically includes:

[0081] 1) Based on the superheater energy flow model, obtain the thermal conductivity of the hot fluid inside the metal tube wall and the thermal conductivity of the cold fluid inside the metal tube wall. Specifically, the thermal conductivity of the hot fluid inside the metal tube wall and the thermal conductivity of the cold fluid inside the metal tube wall are determined based on the mass and length of the superheater.

[0082] 2) For each section of the superheater in the superheater energy flow model, the equivalent cold fluid thermal resistance is calculated based on the cold fluid heat capacity flow and the thermal conductivity of the cold fluid inside the metal tube wall. The equivalent hot fluid thermal resistance is calculated based on the hot fluid heat capacity flow and the thermal conductivity of the hot fluid inside the metal tube wall. The equivalent cold fluid thermal resistance and the equivalent hot fluid thermal resistance constitute the equivalent thermal resistance data of the superheater. Specifically, the equivalent cold fluid thermal resistance and the equivalent hot fluid thermal resistance are calculated using the following formulas:

[0083]

[0084] Among them, R ih R represents the equivalent thermal resistance data of the hot fluid in the i-th segment of the superheater. ic This represents the equivalent thermal resistance data of the cold fluid in the i-th segment of the superheater, k. i，h A i，h Let k represent the thermal conductivity of the hot fluid in the i-th segment of the superheater. i，c A i，c This represents the thermal conductivity of the cold fluid in the i-th segment of the superheater.

[0085] Step 400: Based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model, determine the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model; the tube wall temperatures of multiple superheaters constitute state variables.

[0086] Specifically, once the heat capacity flow rate parameters of each superheater section are determined, they are input into the actual thermal power unit corresponding to the superheater energy flow model. The DCS component of the thermal power unit records the temperature data of multiple superheaters in the unit, including the input temperature and tube wall temperature of each superheater section, and stores this data in the DCS database. It is important to note that no clear linear relationship has yet been found between heat capacity flow rate and the thermal energy output of the thermal power unit. Therefore, by converting the heat capacity flow rate into the corresponding tube wall temperature, a linear relationship between the tube wall temperature and the thermal energy output of the thermal power unit can be determined, facilitating subsequent calculations and improving the accuracy of subsequent assessments of the thermal energy output of the thermal power unit.

[0087] That is, first determine the input variable u, u = [G 1，c G 2，c G 3，c G 1，h G 2，h G 3，h ] T , representing the heat capacity flow rate parameter of the hot and cold fluids in each superheater section; its corresponding state variable x is obtained from the DCS database of the thermal power unit, x = [T w1 T w2 T w3 ] T .

[0088] Step 500: Input the state variables into the preset heat transfer state equation and the preset heat transfer output equation respectively, and calculate the output heat energy of each superheater segment by combining the equations. The preset heat transfer state equation is determined based on the equivalent thermal resistance data of each superheater segment and the input temperature of each superheater segment. The preset heat transfer output equation is determined based on the equivalent thermal resistance data of each superheater segment, the tube wall temperature of each superheater segment, and the input temperature of each superheater segment.

[0089] First, a preset heat transfer state equation is used to simultaneously characterize the heat transfer of different heat exchangers, enabling iterative calculations to obtain a more accurate output. The preset heat transfer state equation is:

[0090] Where x represents the state variable, used to evaluate the heat storage capacity of each section of the superheater, x = [T w1 T w2 T w3 ] T T wi M represents the tube wall temperature of the i-th superheater segment. i T represents the metal mass of the i-th superheater segment. hi,in Indicates the first i The input temperature of the hot fluid in the superheater, T ci,inLet u represent the input temperature of the cold fluid in the i-th superheater segment, and let u represent the implicit variable; i∈[1,2,3], the first superheater segment is the primary superheater, the second superheater segment is the screen-type superheater, and the third superheater segment is the final superheater.

[0091] To evaluate the heat transfer process, Q is selected. i (i = 1, 2, ..., 6) are used as output variables of the multi-stage segmented system to form the output vector (heat storage) y, where y represents the total heat storage of the thermal power unit.

[0092] y = [Q1, Q2, Q3, Q4, Q5, Q6] T ,

[0093] Wherein, Q1 represents the heat exchange of the cold fluid in the primary superheater, that is, the output heat energy of the primary superheater; Q2 represents the heat exchange of the cold fluid in the screen superheater, that is, the output heat energy of the screen superheater; Q3 represents the heat exchange of the cold fluid in the final superheater, that is, the output heat energy of the final superheater; Q4 represents the metal heat storage in the primary superheater; Q5 represents the metal heat storage in the screen superheater; and Q6 represents the metal heat storage in the final superheater.

[0094] The metal heat storage in the superheater is the main element for heat storage and reflecting the primary frequency regulation capability. The heat exchange of the cold fluid inside each section of the superheater and the heat storage of the tube wall are important parameters reflecting the unit's output capacity.

[0095] The formula for calculating the output vector y can be written as the output equation:

[0096] y = Cx + D

[0097] C and D describe the changes in the output variables caused by changes in the input and state variables.

[0098] In summary, the heat transfer system corresponding to a thermal power unit can be described by state equations and output equations, and can be simplified as follows:

[0099]

[0100] Based on the above equations, the heat storage capacity y can be accurately characterized. An important reason for establishing a state-space expression is that it can accurately characterize the boiler's heat storage capacity and be corrected based on historical data to obtain the precise heat energy at the outlet of each superheater in real time, that is, the output heat energy of each superheater.

[0101] Step 600: Calculate the output thermal energy of the thermal power unit based on the output thermal energy of each superheater segment.

[0102] Step 600 specifically includes:

[0103] 1) Obtain the input thermal energy of the thermal power unit; specifically, based on the outlet pressure p of the steam-water separator. s and temperature T c1,in Based on the preset enthalpy online calculation table, the enthalpy h entering the primary superheater is found and determined. in This serves as the energy input at the inlet side of the thermal power unit; then, the input thermal energy of the thermal power unit is calculated according to the following formula:

[0104] Q0 = h in *m in ; where h in and m in These are the inlet-side enthalpy and mass flow rate, respectively.

[0105] 2) Add the input thermal energy of the thermal power unit and the output thermal energy of each section of the superheater to obtain the output thermal energy of the thermal power unit. Specifically, the output thermal energy of the thermal power unit is calculated using the following formula:

[0106] Q = Q0 + Q1 + Q2 + Q3.

[0107] This invention accurately characterizes the Q-value heat transfer process, providing a precise characterization of energy storage under frequent operation of thermal power units at present. This is of great significance for maintaining the stability of the power grid and ensuring the safe and efficient operation of thermal power units.

[0108] In summary, this invention establishes heat transfer state equations and heat transfer output equations based on dynamic energy flow models of superheaters and reheaters under different processes, especially dynamic changes, and calculates the heat of the working fluid in dynamic processes, thereby improving the accuracy of the energy possessed by the working fluid. Figure 4 The figure shows a comparison of the calculated thermal energy stored in the working fluid under different operating conditions. Obviously, the present invention can achieve a more accurate and real-time characterization of the output thermal energy of thermal power units.

[0109] Example 2

[0110] like Figure 5 As shown, in order to implement the technical solution in Embodiment 1, this embodiment provides a thermal power unit energy storage characterization system based on heat flow modeling. The thermal power unit includes multiple superheaters connected in sequence. The thermal power unit energy storage characterization system includes:

[0111] The model building module 101 is used to establish a superheater energy flow model corresponding to the thermal power unit based on preset superheater operating conditions.

[0112] The parameter determination module 201 is used to determine the heat capacity flow parameters of each section of the superheater in the superheater energy flow model.

[0113] The equivalent thermal resistance calculation module 301 is used to calculate the equivalent thermal resistance data corresponding to each segment of the superheater based on the heat capacity flow parameters of each segment of the superheater.

[0114] Temperature determination module 401 is used to determine the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model; the tube wall temperatures of multiple superheaters constitute state variables.

[0115] The output heat energy calculation module 501 is used to input the state variables into the preset heat transfer state equation and the preset heat transfer output equation respectively, so as to calculate the output heat energy of each segment of the superheater simultaneously; the preset heat transfer state equation is determined based on the equivalent thermal resistance data of each segment of the superheater and the input temperature of each segment of the superheater; the preset heat transfer output equation is determined based on the equivalent thermal resistance data of each segment of the superheater, the tube wall temperature of each segment of the superheater and the input temperature of each segment of the superheater.

[0116] The unit output thermal energy determination module 601 is used to calculate the output thermal energy of the thermal power unit based on the output thermal energy of each section of the superheater.

[0117] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0118] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for characterizing the energy storage of thermal power units based on heat flow modeling, wherein the thermal power unit comprises multiple superheaters connected in sequence, characterized in that, Energy storage characterization methods for thermal power units include: Based on the preset superheater operating conditions, a superheater energy flow model corresponding to the thermal power unit is established. Determine the heat capacity and flow rate parameters of each section of the superheater in the superheater energy flow model; Based on the heat capacity flow parameters of each superheater segment, calculate the equivalent thermal resistance data corresponding to each superheater segment. Based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model, the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model are determined; the tube wall temperatures of multiple superheaters constitute state variables; The state variables are input into the preset heat transfer state equation and the preset heat transfer output equation respectively, and the output heat energy of each superheater segment is calculated simultaneously. The preset heat transfer state equation is determined based on the equivalent thermal resistance data of each superheater segment and the input temperature of each superheater segment. The preset heat transfer output equation is determined based on the equivalent thermal resistance data of each superheater segment, the tube wall temperature of each superheater segment, and the input temperature of each superheater segment. The output thermal energy of the thermal power unit is calculated based on the output thermal energy of each superheater segment.

2. The method for characterizing the energy storage of thermal power units based on heat flow modeling according to claim 1, characterized in that, The thermal power unit includes a primary superheater, a screen-type superheater, and a final superheater connected in sequence; the equivalent thermal resistance data corresponding to each superheater segment includes the equivalent thermal resistance data of the cold fluid in the superheater and the equivalent thermal resistance data of the hot fluid in the superheater; the input temperature corresponding to each superheater segment includes the input temperature of the hot fluid in the superheater and the input temperature of the cold fluid in the superheater. The preset heat transfer state equation is: in, x represents a state variable, x = [T] w1 ,T w2 ,T w3 ] T T wi c represents the tube wall temperature of the i-th superheater segment. p M represents the specific heat capacity of the metal tube wall. i R represents the metal mass of the i-th superheater segment. ih R represents the equivalent thermal resistance data of the hot fluid in the i-th segment of the superheater. ic T represents the equivalent thermal resistance data of the cold fluid in the i-th segment of the superheater. hi,in Indicates the first i The input temperature of the hot fluid in the superheater, T ci,in Let u represent the input temperature of the cold fluid in the i-th superheater segment, and let u represent the implicit variable; i∈[1,2,3], the first superheater segment is the primary superheater, the second superheater segment is the screen-type superheater, and the third superheater segment is the final superheater.

3. The method for characterizing the energy storage of thermal power units based on heat flow modeling according to claim 2, characterized in that, The preset heat transfer output equation is: y = g(x, u, t); Where y = Cx + D, y represents the total heat storage of the thermal power unit, y = [Q1, Q2, Q3, Q4, Q5, Q6] T , Q1 represents the heat exchange of the cold fluid in the primary superheater, i.e., the output heat energy of the primary superheater; Q2 represents the heat exchange of the cold fluid in the screen superheater, i.e., the output heat energy of the screen superheater; Q3 represents the heat exchange of the cold fluid in the final superheater, i.e., the output heat energy of the final superheater; Q4 represents the heat storage of the metal in the primary superheater; Q5 represents the heat storage of the metal in the screen superheater; and Q6 represents the heat storage of the metal in the final superheater.

4. The method for characterizing the energy storage of thermal power units based on heat flow modeling according to claim 1, characterized in that, The establishment of the superheater energy flow model corresponding to the thermal power unit based on preset superheater operating conditions specifically includes: Based on the basic data of the thermal power unit, a physical model of the superheater is established. The basic data of the thermal power unit includes the number and connection sequence of the superheaters in the thermal power unit, the specific heat capacity of the metal tube wall, the metal mass of each superheater section, the thermal conductivity of the hot fluid inside the metal tube wall, and the thermal conductivity of the cold fluid inside the metal tube wall. Based on the preset boiler superheater operating conditions and the superheater physical model, a superheater energy flow model corresponding to the thermal power unit is established.

5. The method for modeling thermal power units based on dynamic energy flow according to claim 1, characterized in that, Determining the heat capacity flow parameters of each superheater segment in the superheater energy flow model specifically includes: For each section of the superheater in the superheater energy flow model, obtain the cold fluid flow rate and the hot fluid flow rate in the superheater. Based on the heat exchanger energy flow model, the specific heat capacity of the metal tube wall is obtained; Calculate the cold fluid heat capacity flow rate based on the cold fluid flow rate and the specific heat capacity of the metal pipe wall; The heat capacity flow rate of the hot fluid is calculated based on the flow rate of the hot fluid and the specific heat capacity of the metal tube wall; the heat capacity flow rate of the cold fluid and the heat capacity flow rate of the hot fluid constitute the heat capacity flow rate parameters of the superheater.

6. The method for modeling thermal power units based on dynamic energy flow according to claim 5, characterized in that, Based on the heat capacity flow rate parameters of each superheater segment, the equivalent thermal resistance data corresponding to each superheater segment is calculated, specifically including: Based on the heat exchanger energy flow model, the thermal conductivity of the hot fluid inside the metal pipe wall and the thermal conductivity of the cold fluid inside the metal pipe wall are obtained. For each section of the superheater in the superheater energy flow model, the equivalent cold fluid thermal resistance is calculated based on the cold fluid heat capacity flow and the thermal conductivity of the cold fluid inside the metal tube wall, and the equivalent hot fluid thermal resistance is calculated based on the hot fluid heat capacity flow and the thermal conductivity of the hot fluid inside the metal tube wall; the equivalent cold fluid thermal resistance and the equivalent hot fluid thermal resistance constitute the equivalent thermal resistance data of the superheater.

7. The method for modeling thermal power units based on dynamic energy flow according to claim 1, characterized in that, Based on the output thermal energy of each superheater segment, the output thermal energy of the thermal power unit is calculated, specifically including: Obtain the input thermal energy of the thermal power unit; The input thermal energy of the thermal power unit and the output thermal energy of each section of the superheater are added together to obtain the output thermal energy of the thermal power unit.

8. A thermal power unit energy storage characterization system based on heat flow modeling, wherein the thermal power unit comprises multiple superheaters connected in sequence, characterized in that, The energy storage characterization system for thermal power units includes: The model building module is used to establish a superheater energy flow model corresponding to the thermal power unit based on preset superheater operating conditions. The parameter determination module is used to determine the heat capacity flow parameters of each section of the superheater in the superheater energy flow model. The equivalent thermal resistance calculation module is used to calculate the equivalent thermal resistance data corresponding to each segment of the superheater based on the heat capacity flow parameters of each segment of the superheater. The temperature determination module is used to determine the tube wall temperature of each superheater segment and the input temperature of each superheater segment in the superheater energy flow model based on the heat capacity flow parameters of each superheater segment and the superheater energy flow model; the tube wall temperatures of multiple superheaters constitute state variables; The output heat energy calculation module is used to input the state variables into the preset heat transfer state equation and the preset heat transfer output equation respectively, so as to calculate the output heat energy of each superheater segment simultaneously; the preset heat transfer state equation is determined based on the equivalent thermal resistance data of each superheater segment and the input temperature of each superheater segment; the preset heat transfer output equation is determined based on the equivalent thermal resistance data of each superheater segment, the tube wall temperature of each superheater segment, and the input temperature of each superheater segment. The unit output thermal energy determination module is used to calculate the output thermal energy of the thermal power unit based on the output thermal energy of each section of the superheater.

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