Primary frequency regulation dynamic simulation method and apparatus based on thermal power condensate water throttling strategy

Abstract

Provided in the present invention are a primary frequency regulation dynamic simulation method and apparatus based on a thermal power condensate water throttling strategy, which are used for analyzing the dynamic characteristics of a unit when a power plant executes a primary frequency regulation instruction by means of a condensate water throttling strategy after a power disturbance occurs in a power grid. The dynamic characteristics mainly comprise the characteristics of a steam turbine speed governor system, the characteristics of a variable-frequency condensate pump system, the dynamic heat exchange characteristics of a low-pressure heater and extraction steam, the flow characteristics of an extraction steam pipeline, and the output characteristics of a steam turbine body. A moving boundary method is mainly applied to a heat exchange process between condensate water (a cold fluid) and shell-side extraction steam (a hot fluid) in a low-pressure heater. The heat exchange process between the cold and hot fluids can be divided into a superheated section, a phase change section and a subcooled section on the basis of the aggregation state of the extraction steam. When the moving boundary method is applied to a steam turbine regenerative system, the dynamic variation laws of extraction steam temperature and pressure can be more accurately obtained, and the extraction steam pressure on a low-pressure heater side is a key factor in determining the extraction steam flow rate on a low-pressure cylinder side, and is also critical in determining the instantaneous power increment of a steam turbine. Moving boundary method-based frequency regulation dynamic simulation for thermal power condensate water throttling takes into account relatively comprehensive actual process factors, and only one-dimensional modeling along an axial main flow direction is taken into account, thus combining the advantages of fast and accurate simulation. A fast and accurate simulation method is a prerequisite for implementing power grid frequency security analysis. By mastering the dynamic process of power plant load response from the moment a frequency deviation exceeds a dead band to the moment same returns to the dead band, a foundation can be provided for the primary frequency regulation control of power plants and the frequency security analysis of power grids.

Description

Primary frequency regulation dynamic simulation method and device based on condensate throttling strategy of thermal power TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and in particular to a primary frequency regulation dynamic simulation method and device based on a condensate throttling strategy of thermal power. BACKGROUND

[0002] Thermal power units are positioned as regulatory power sources, which are the main providers of multi-time scale regulation capability of new power systems. Primary frequency is the process of restoring the grid frequency by adjusting the power of the power source when a disturbance (load disturbance, power shortage of generator units, power fluctuation of new energy) occurs. Frequency control is the basis for ensuring the safe and stable operation of a power system, and internal and external reasons determine that thermal power units need to improve primary frequency regulation capability. The condensate throttling primary frequency regulation strategy is a method for improving the rapid load change of thermal power units to provide primary frequency regulation capability for the power grid. The principle is to reduce the flow of condensate into each stage of the low-pressure heater, reduce the amount of steam extracted from the turbine into the low-pressure heater, and equivalently use the heat storage of the turbine to rapidly increase the expansion work of the turbine. The specific methods include two kinds: the first kind is to reduce the frequency of the condensate pump, which reduces the flow into each stage of the low-pressure heater, increases the outlet temperature and pressure of the low-pressure heater, and reduces the extraction flow into the low-pressure heater; the second kind is to directly adjust the extraction flow for the situation where there is a regulating valve on the extraction pipe, but most units have only on-off valves and do not have the function of adjusting the flow.

[0003] When condensate throttling is used for primary frequency regulation, both the power grid and the power plant lack a dynamic simulation method for evaluating the primary frequency regulation of this process. The power grid needs to master the primary frequency regulation capability under this strategy in order to pre-plan the number of units participating in frequency regulation for the entire grid in response to different disturbances. In terms of primary frequency regulation simulation, the power system already has a comprehensive primary frequency transient simulation model, including the governor system of thermal power units, boilers, steam turbines, and the governor system of hydroelectric units and water turbine models. However, the above-mentioned models are mainly developed for high-governor primary frequency regulation strategies and do not consider the extraction of steam between the turbine and the low-pressure heater, and the heat exchange process between the internal steam of the low-pressure heater and the condensate. Therefore, in order to evaluate the primary frequency regulation capability under the condensate throttling strategy, a joint model of the turbine governor system-turbine-extraction pipe-low-pressure heater-deaerator, etc. needs to be established.

[0004] The existing low-pressure heater heat exchange process has been considered in the three-dimensional simulation of the thermal system of a coal-fired power unit. However, the modeling method considering the three-dimensional model distributed parameters needs to gradually solve the energy conservation, mass conservation, momentum conservation equations and other equations of a large number of space nodes, and the simulation speed is too slow to be used for power grid transient simulation. Therefore, the one-dimensional modeling and solving method should be considered. The one-dimensional heat exchange model of the condensate throttling strategy is mainly composed of partial differential equations. Since the partial differential equations lack a unified analytical solution, the commonly used characteristic line method is to convert the partial differential into a common differential equation group by being a function of two independent variables. However, the initial condition and boundary condition requirements are very high. Usually, the dynamic heat exchange process still needs to be solved by using a numerical method. Since the simulation accuracy of the steam and condensate heat exchange in the low-pressure heater in the time scale of one minute directly determines the dynamic characteristics of the extraction flow reduction, and also determines the flow and power dynamic process of the steam turbine, the accuracy of the primary frequency modulation has a great influence on the high-precision transient simulation of the power grid. Therefore, in order to improve the primary frequency modulation dynamic characteristics of the thermal power when the condensate throttling strategy is adopted, the original partial differential equation group needs to be simplified appropriately, and a numerical solution method is used to solve it.

[0005] At present, the main simulation methods of the dynamic characteristics of the heat exchanger mainly include two types. One type is to regard the fluid in the phase change process as a whole, and assumes that the state parameters of the entire heat exchange section are the same in space. Since the heat exchange coefficient in the actual phase change section is much larger than that in the superheating section and the subcooling section, obviously, such a lumped parameter method has a large error and is difficult to achieve accurate modeling. The second type of method is the distributed parameter method, which considers the temperature difference of each point in space. A more accurate method is to divide the heat exchange section into three sections of subcooling, two-phase and superheating, and to separately discretize and numerically solve each section. However, the division of nodes is too dense, resulting in a very long calculation speed, and it is especially difficult to solve the equation group using an implicit format. In order to solve the above problems, the moving boundary method is introduced into the dynamic heat exchange of the condensate throttling frequency modulation simulation of the thermal power. The moving boundary method does not consider the state parameter difference of each space node after the three sections are discretized, but regards each section as a whole. However, the length of each section changes with time. This method actually considers the difference of the heat exchange coefficients of the three sections and the change of the length of each section, and the number of unknowns is less than that of the discretization of the entire heat exchange section. It meets the requirements of simulation accuracy and speed.

[0006] In summary, the existing technology has the problems of low simulation accuracy and slow simulation speed.

[0007] SUMMARY

[0008] The present application provides a kind of based on the primary frequency modulation dynamic simulation method and device of condensate throttling strategy of thermal power, to solve the defects of low simulation accuracy and slow simulation speed in prior art, realize the high-precision, fast frequency modulation dynamic simulation.

[0009] The present application provides a kind of based on the primary frequency modulation dynamic simulation method of condensate throttling strategy of thermal power, applied to thermal power unit, comprising:

[0010] According to the steam extraction aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, a steam heat release model and a condensate water heat absorption model are established along the flow direction of the cold and hot fluid by using a moving boundary method; a thermal power generating unit simulation model is obtained according to a pre-constructed steam extraction pipeline flow characteristic equation, a pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model and the condensate water heat absorption model.

[0011] In response to the voltage frequency difference exceeding a dead zone, a condensate water flow step signal is obtained, and the condensate water flow step signal is input to the pre-constructed thermal power generating unit simulation model for simulation calculation to obtain a steam turbine power increment dynamic value.

[0012] According to the steam extraction aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, a steam heat release model and a condensate water heat absorption model are established along the flow direction of the cold and hot fluid by using a moving boundary method, and specifically include:

[0013] According to the parameter changes of the cold and hot fluid along the flow direction in the heat exchange process, the heat exchange process is divided into a superheating section, a two-phase section and a subcooling section, and the lengths of the superheating section, the two-phase section and the subcooling section are set as variables with respect to time;

[0014] The energy conservation, mass conservation and property equation of steam heat release in the superheating section, the two-phase section and the subcooling section are sequentially constructed to obtain a steam heat release model; the energy conservation, mass conservation and property equation of condensate water heat absorption in the superheating section, the two-phase section and the subcooling section are sequentially constructed to obtain a condensate water heat absorption model.

[0015] According to the steam extraction aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, a steam heat release model and a condensate water heat absorption model are established along the flow direction of the cold and hot fluid by using a moving boundary method, and specifically include:

[0016] Initial parameters are obtained; wherein the initial parameters include an initial pressure of a steam extraction point, an initial temperature of a steam extraction point, a condensate water inlet temperature, a condensate water inlet pressure and a target load;

[0017] The initial parameters are input to the thermal power generating unit simulation model for solving to obtain steady-state parameters;

[0018] The steady-state parameters and the condensate water flow step signal are input to the thermal power generating unit simulation model for iterative solving to obtain a steam turbine power increment dynamic value.

[0019] According to the method, the steady state parameters and the condensate flow step signal are input into the thermal power unit simulation model for iterative solving to obtain a steam turbine power increment dynamic value, and the method specifically comprises the following steps:

[0020] S1: inputting the steady state parameters and the initial value of the condensate flow step signal into the thermal power unit simulation model to obtain parameter values at an initial time;

[0021] S2: inputting the parameter values at the initial time into the thermal power unit simulation model to obtain a target iteration formula; the target iteration formula comprises a steam turbine power iteration equation at a current time and a previous time;

[0022] S3: setting a steam turbine power at a current time step as a hypothetical value, solving a current solving equation according to the hypothetical value, verifying the solving result in a supercooling section property equation, recording the hypothetical value and jumping to step S4 if the equation is correct, and updating the hypothetical value according to a preset power value iteration rule and repeating step S3 if the equation is incorrect; wherein the current solving equation comprises a steam heat release model of a superheating section, a steam heat release model of the superheating section, a steam heat release model of a two-phase section and a steam heat release model of the two-phase section, and a mass conservation and energy conservation equation of the supercooling section;

[0023] S4: adding one to the current time step, repeating steps S3-S4 until a steam turbine power curve obtained according to the hypothetical value meets a preset ending condition, and obtaining a steam turbine power increment dynamic value according to the steam turbine power curve.

[0024] According to the method, the steam heat release model comprises:

[0025] a superheating section:

[0026] wherein, ρ h1s is a superheating section density average value, u h1s is a superheating section flow velocity average value, τ is time, x is a distance along a flow direction, h h1s is a superheating section enthalpy average value, P h1s is a superheating section pressure average value, k h1s is a superheating section heat transfer coefficient average value, T h1s is a superheating section temperature average value, T c,h1s is a condensate section average temperature corresponding to steam extraction of a two-phase section, D is a pipe diameter, A is a condensate and steam heat exchange area, ρ 1s is a superheating section density inlet value, u 1s is a superheating section flow velocity inlet value, h h1sis the enthalpy value of the superheating section, P 1s is the pressure value of the superheating section, T 1s is the temperature value of the superheating section;

[0027] Two-phase section:

[0028] wherein, ρ h2 is the density average value of the two-phase section, u h2 is the flow velocity average value of the two-phase section, τ is time, and x is distance along the flow direction, h h2 is the enthalpy average value of the two-phase section, P h2 is the pressure average value of the two-phase section, k h2 is the heat transfer coefficient average value of the two-phase section, T h2 is the temperature average value of the two-phase section, T c,h2 is the average temperature of the condensate section corresponding to the extraction steam of the superheating section, D is the pipe diameter, A is the heat exchange area of the condensate and the extraction steam, ρ sl is the density value of the saturated steam, λ is the dryness, ρ sv is the density value of the saturated water, h sl is the enthalpy value of the saturated steam;

[0029] Subcooling section:

[0030] wherein, ρ h1v is the density average value of the subcooling section, u h1v is the flow velocity average value of the subcooling section, τ is time, and x is distance along the flow direction, h h1v is the enthalpy average value of the subcooling section, P h1v is the pressure average value of the subcooling section, k h1v is the heat transfer coefficient average value of the subcooling section, T h1v is the temperature average value of the subcooling section, T c,h1v is the average temperature of the condensate section corresponding to the extraction steam of the subcooling section, D is the pipe diameter, and A is the heat exchange area of the condensate and the extraction steam.

[0031] According to the one-time frequency modulation dynamic simulation method based on the power plant condensate throttling strategy provided by the application, the condensate heat absorption model comprises:

[0032] wherein, ρ c is the density average value of the condensate corresponding to the extraction steam of the subcooling, two-phase, and superheating sections, u c is the flow velocity average value of the condensate corresponding to the extraction steam of the subcooling, two-phase, and superheating sections, τ is time, and x is distance along the flow direction, k c is the heat transfer coefficient average value of the condensate corresponding to the extraction steam of the subcooling, two-phase, and superheating sections, T c is the temperature average value of the condensate corresponding to the extraction steam of the subcooling, two-phase, and superheating sections, cp T is the average value of the specific heat capacity of the condensate water corresponding to the extraction steam of the supercooling, two-phase, and superheating sections, T h2 T is the average value of the temperature of the two-phase section, T h1v T is the average value of the temperature of the supercooling section, T h1s T is the average value of the temperature of the superheating section, D is the pipe diameter, and A is the heat exchange area of the condensate water and the extraction steam.

[0033] The application also provides a primary frequency modulation dynamic simulation device based on a power plant condensate water throttling strategy, which is applied to a power plant unit and includes:

[0034] A model unit is configured to establish a steam heat release model and a condensate water heat absorption model along the flow direction of the cold and hot fluids by using a moving boundary method according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the power plant unit, and to obtain a power plant simulation model according to a pre-constructed extraction steam pipeline flow characteristic equation, a pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model, and the condensate water heat absorption model.

[0035] A simulation unit is configured to obtain a condensate water flow step signal in response to a voltage frequency difference exceeding a dead zone, input the condensate water flow step signal to the pre-constructed power plant simulation model for simulation calculation, and obtain a steam turbine power increment dynamic value.

[0036] The application also provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the primary frequency modulation dynamic simulation method based on the power plant condensate water throttling strategy according to any one of the above.

[0037] The application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program is executable on a processor to implement the primary frequency modulation dynamic simulation method based on the power plant condensate water throttling strategy according to any one of the above.

[0038] The application also provides a computer program product including a computer program, and the computer program is executable on a processor to implement the primary frequency modulation dynamic simulation method based on the power plant condensate water throttling strategy according to any one of the above.

[0039] The application provides a primary frequency modulation dynamic simulation method and device based on a condensate throttling strategy of thermal power, and the method comprises the following steps: establishing a steam heat release model and a condensate heat absorption model along the flow direction of cold and hot fluids by using a moving boundary method according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the thermal power unit; obtaining a thermal power unit simulation model according to a pre-constructed extraction steam pipeline flow characteristic equation, a pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model and the condensate heat absorption model; obtaining a steam turbine power increment dynamic value by inputting a condensate flow step signal into the pre-constructed thermal power unit simulation model for simulation calculation in response to the voltage frequency difference exceeding a dead zone. The application uses the moving boundary method to model the dynamic heat exchange process of the thermal power unit, and only considers one-dimensional modeling along the axial main flow direction, so that the advantages of fast and accurate simulation are achieved, and the frequency modulation dynamic simulation with high precision and speed is realized. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the present application or 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 be obtained by those skilled in the art without creative effort.

[0041] Fig. 1 is a flowchart of the primary frequency modulation dynamic simulation method based on the condensate throttling strategy of thermal power provided by the present application;

[0042] Fig. 2 is a flowchart of the primary frequency modulation dynamic simulation method based on the condensate throttling strategy of thermal power provided by the present application;

[0043] Fig. 3 is a structural schematic diagram of the primary frequency modulation dynamic simulation device based on the condensate throttling strategy of thermal power provided by the present application;

[0044] Fig. 4 is a structural schematic diagram of the electronic device provided by the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions in the present application will be described clearly and completely in the following with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0046] The primary frequency modulation dynamic simulation method based on the condensate throttling strategy of thermal power provided by the present application will be described in the following with reference to Figs. 1-2, as shown in Fig. 1, the method comprises the following steps:

[0047] Step 110: according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, steam heat release models and condensate heat absorption models are established along the flow direction of the cold and hot fluid by using the moving boundary method; a thermal power generating unit simulation model is obtained according to the pre-constructed extraction steam pipeline flow characteristic equation, the pre-constructed steam turbine flow-power dynamic response equation, the steam heat release models and the condensate heat absorption models;

[0048] In the process of the thermal power generating unit primary frequency modulation dynamic simulation, after the power disturbance of the power grid, the analysis of the unit dynamic characteristics when the power plant executes the primary frequency modulation instruction through the condensate throttling strategy is the main content of the primary frequency modulation dynamic simulation. The dynamic characteristics mainly include the steam turbine governor system, the condensate pump frequency conversion system, the low-pressure heater and extraction dynamic heat exchange characteristics, the extraction steam pipeline flow characteristics and the steam turbine output characteristics.

[0049] That is, the construction of the simulation model needs to consider the restoration of the above-mentioned dynamic characteristics. The steam heat release models and the condensate heat absorption models are constructed for the low-pressure heater and extraction dynamic heat exchange characteristics by using the moving boundary method, and the thermal power generating unit simulation model is obtained in combination with the steam turbine flow-power dynamic response equation and the extraction steam pipeline flow characteristic equation. The thermal power generating unit simulation model obtained in this way can simultaneously consider the whole process of the governor system-condensate pump-condensate and steam three-stage heat exchange-extraction steam flow change-steam turbine power dynamics.

[0050] It needs to be noted that in the embodiment of the present application, the moving boundary method is mainly applied to the modeling of the condensate water (cold fluid) and the shell side extraction steam (hot fluid) heat exchange process in the low-pressure heater. That is, the moving boundary method is used for the modeling of the steam turbine regenerative system, so that the dynamic extraction steam temperature and pressure variation law can be obtained more accurately. It can be understood that the low-pressure heater side extraction steam pressure is the key to determining the low-pressure cylinder side extraction steam flow and the key to determining the instantaneous power increment of the steam turbine. The accurate modeling of the dynamic extraction steam temperature and pressure variation law can provide a solid foundation for the primary frequency modulation control of the power plant and the frequency safety analysis of the power grid.

[0051] In the actual operation process, the thermal power generating unit simulation model includes the extraction steam pipeline flow characteristic equation, the steam turbine flow-power dynamic response equation, the steam heat release models and the condensate heat absorption models. In the process of constructing the thermal power generating unit simulation model, the steam heat release models and the condensate heat absorption models are constructed along the flow direction of the cold and hot fluid by using the moving boundary method according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit.

[0052] In some embodiments, the steam extraction aggregation state of the heat exchange process of the thermal power unit is used to establish a steam heat release model and a condensed water heat absorption model along the flow direction of the cold and hot fluids by using a moving boundary method, and specifically comprises:

[0053] According to the parameter changes of the cold and hot fluids along the flow direction in the heat exchange process, the heat exchange process is divided into a superheating section, a two-phase section and a supercooling section, and the lengths of the superheating section, the two-phase section and the supercooling section are set as variables with respect to time.

[0054] The energy conservation, mass conservation and property equations of steam heat release in the superheating section, the two-phase section and the supercooling section are sequentially constructed to obtain a steam heat release model; and the energy conservation, mass conservation and property equations of condensed water heat absorption in the superheating section, the two-phase section and the supercooling section are sequentially constructed to obtain a condensed water heat absorption model.

[0055] Specifically, first of all, it needs to be pointed out that the steam extraction aggregation state refers to the process in which the internal steam of a thermodynamic system diffuses to the outside due to the effect of external steam extraction, so that the pressure of the internal steam is reduced. In this process, the state of matter changes under different temperature and pressure conditions, and thus can be divided into a superheating section, a two-phase section (phase change section) and a supercooling section. Among them, the superheating section refers to the part of a certain substance in the liquid state region whose temperature exceeds the normal boiling point. In the superheated state, although the inside of the liquid is already at a high temperature, the surface has not yet begun to evaporate significantly. If further heating is applied, the superheated liquid may suddenly boil, resulting in a violent release of steam. The two-phase section refers to the temperature and pressure region in which a substance exists in both liquid and gas phases. In this region, the substance can exist in the form of gas-liquid two-phase coexistence. The supercooling section refers to the part of a substance in the liquid state region whose temperature is lower than the normal boiling point. Supercooling usually occurs when a liquid is rapidly cooled to a temperature below its saturated vapor pressure. In the supercooled state, if a trigger factor appears in the liquid, such as the introduction of a gas bubble or stirring, the liquid will rapidly boil.

[0056] On this basis, it can be understood that the condensed water and the steam extraction in the low-pressure heater are arranged in counterflow, and in the process of heat exchange between the cold and hot fluids, the steam extraction on the low-pressure heater side is divided into three sections according to the steam extraction aggregation state: a superheating section, a two-phase section (phase change section) and a supercooling section. According to the above segmentation results, a segmented lumped parameter model is established for the counterflow heat exchange process of the condensed water and the steam extraction, and the length of each section is a variable with respect to time. This partial differential equation solution method in which the boundary moves with time is called the moving boundary method.

[0057] It is also needed to point out that, for the lumped parameter model of the superheating section, two-phase section (phase change section) and subcooling section, in the specific modeling process, only the parameter change of the extraction steam and condensate along the flow direction is considered, the difference of the distribution parameters of the extraction steam and condensate in the pipe cross section is ignored, and it is assumed that the extraction steam and condensate temperature is the same in the pipe circumferential direction, so as to construct the energy conservation, mass conservation and property equation of the steam heat release in the extraction steam superheating section, two-phase section and subcooling section and the condensate heat exchange process, to obtain the steam heat release model, and also to construct the energy conservation, mass conservation and property equation of the condensate heat absorption in the extraction steam superheating section, two-phase section and subcooling section and the condensate heat exchange process, to obtain the condensate heat absorption model.

[0058] In addition, in the process of constructing the equation, the independent variable is time, that is, the functions involved in the steam heat release model and the condensate heat absorption model include: the functions of the average temperature and length of the superheating section, the functions of the average temperature and length of the phase change section, and the functions of the average temperature and length of the subcooling section with time.

[0059] It is needed to note that the way of constructing the steam heat release model and the condensate heat absorption model provided by the embodiment of the present application is one-dimensional modeling along the axial main flow direction, and the one-dimensional modeling is more suitable for the simulation of the transient part of the power grid than the three-dimensional modeling adopted in the prior art. For the simulation of the dynamic characteristics, the moving boundary method is introduced into the dynamic heat exchange of the thermal power condensate throttling frequency modulation simulation in the embodiment of the present application. The moving boundary method does not consider the difference of the state parameters of each space node in the three sections after being discretized, but each section is regarded as a whole, but the length of each section changes with time. This method actually considers the difference of the heat exchange coefficients of the three sections and the change of the length of each section, and the unknowns are less than the discretization of the whole heat exchange section, which meets the requirements of simulation accuracy and speed. The fast and accurate simulation method is the premise of realizing the frequency safety analysis of the power grid. By mastering the dynamic process of the power plant load response from the process that the frequency difference exceeds the dead zone to the process that the frequency difference returns to the dead zone, the power plant primary frequency modulation control and the power grid frequency safety analysis can be provided.

[0060] Further, in some embodiments, the steam heat release model comprises:

[0061] superheating section:

[0062] wherein, firstly, it is needed to point out that the subscript h1s is the average value of the superheating section, 1s is the inlet value of the superheating section, and the subscript c, h1s is the average temperature of the condensate section corresponding to the extraction steam of the two-phase section. On this basis, ρ h1s is the average density of the superheating section, u h1s is the average flow velocity of the superheating section, τ is time, x is the distance along the flow direction, h h1s is the average enthalpy of the superheating section, P h1s is the average pressure of the superheating section, k h1sis the average value of heat transfer coefficient of superheating section, T h1s is the average value of temperature of superheating section, T c,h1s is the average temperature of condensate section corresponding to extraction steam of two-phase section, D is the pipe diameter, A is the heat transfer area of condensate and extraction steam, ρ 1s is the density value of superheating section, u 1s is the flow velocity value of superheating section, h h1s is the enthalpy value of superheating section, P 1s is the pressure value of superheating section, T 1s is the temperature value of superheating section;

[0063] Two-phase section:

[0064] Wherein, firstly, it is needed to point out that subscript h2 indicates the average value of two-phase section, subscript sl indicates the value of saturated steam, subscript sv indicates the value of saturated water, and subscript c, h2 indicates the average temperature of condensate section corresponding to extraction steam of superheating section. On this basis, ρ h2 is the average value of density of two-phase section, u h2 is the average value of flow velocity of two-phase section, τ is time, and x is distance along the flow direction, h h2 is the average value of enthalpy of two-phase section, P h2 is the average value of pressure of two-phase section, k h2 is the average value of heat transfer coefficient of two-phase section, T h2 is the average value of temperature of two-phase section, T c,h2 is the average temperature of condensate section corresponding to extraction steam of superheating section, D is the pipe diameter, and A is the heat transfer area of condensate and extraction steam. sl is the density value of saturated steam, λ is dryness, ρ sv is the density value of saturated water, h sl is the enthalpy value of saturated steam;

[0065] Subcooling section:

[0066] Wherein, firstly, it is needed to point out that subscript h1v indicates the average value of subcooling section, and subscript c, h1v indicates the average temperature of condensate section corresponding to extraction steam of subcooling section. On this basis, ρ h1v is the average value of density of subcooling section, u h1v is the average value of flow velocity of subcooling section, τ is time, and x is distance along the flow direction, h h1v is the average value of enthalpy of subcooling section, P h1v is the average value of pressure of subcooling section, k h1v is the average value of heat transfer coefficient of subcooling section, T h1v is the average value of temperature of subcooling section, T c,h1v is the average temperature of condensate section corresponding to extraction steam of subcooling section, D is the pipe diameter, and A is the heat transfer area of condensate and extraction steam.

[0067] Further, in some embodiments, the condensate water heat absorption model comprises:

[0068] Wherein, subscript c represents the average value of the condensate water of the supercooling, two-phase, superheating extraction steam. On this basis, ρ c is the average value of the condensate water density of the supercooling, two-phase, superheating extraction steam, u c is the average value of the condensate water flow rate of the supercooling, two-phase, superheating extraction steam, τ is time, x is distance along the flow direction, k c is the average value of the condensate water heat transfer coefficient of the supercooling, two-phase, superheating extraction steam, T c is the average value of the condensate water temperature of the supercooling, two-phase, superheating extraction steam, c p is the average value of the condensate water specific heat capacity of the supercooling, two-phase, superheating extraction steam, T h2 is the average value of the two-phase section temperature, T h1v is the average value of the supercooling section temperature, T h1s is the average value of the superheating section temperature, D is the pipe diameter, and A is the heat exchange area of the condensate water and the extraction steam.

[0069] Further, the present application does not limit the construction method of the flow characteristic equation of the extraction steam pipeline and the flow-power dynamic response equation of the steam turbine, and the actual situation can be constructed according to the actual situation.

[0070] It should be noted that the extraction steam pipeline referred to in the embodiments of the present application is the extraction steam pipeline connecting the extraction steam point of the steam turbine and the low-pressure heater.

[0071] In some embodiments, the flow characteristic equation of the extraction steam pipeline comprises:

[0072] Wherein, f i is the characteristic coefficient of the extraction steam pipeline group, P h0s6 is the extraction steam point pressure on the steam turbine side, P hi,end is the extraction steam pressure on the low-pressure heater side; G h1s is the extraction steam mass flow rate entering the heat exchange of the low-pressure heater, A is the heat exchange area of the condensate water and the extraction steam, ρ h1s is the average value of the density, u h1s is the average value of the flow rate.

[0073] In some embodiments, the flow-power dynamic response equation of the steam turbine can directly adopt the IEEE standard model of the steam turbine in the primary frequency modulation process, and the present application does not make further description here.

[0074] Step 120: in response to the voltage frequency difference exceeding the dead zone, obtaining a condensate flow step signal, inputting the condensate flow step signal into a pre-constructed thermal power generating unit simulation model for simulation calculation to obtain a steam turbine power increment dynamic value.

[0075] After the simulation model is constructed, the simulation calculation of primary frequency modulation can be performed. In the actual calculation process, the steam heat release model and the condensate heat absorption model can jointly constitute a low-pressure heater condensate and extraction steam dynamic heat exchange model based on the moving boundary method, which is mainly used for calculating the low-pressure heater extraction steam inlet side pressure and the condensate temperature rising process. The functions involved in the calculation process include: functions of average temperature and length of the superheated section, functions of average temperature and length of the phase change section, and functions of average temperature and length of the subcooled section. The inputs are dynamic values of extraction steam flow and condensate flow (condensate flow step signal) and inlet temperature values of the two, and the outputs are extraction steam inlet pressure change curve and condensate outlet temperature.

[0076] On this basis, it needs to be noted that the input extraction steam flow dynamic value is determined by the steam turbine low-pressure cylinder extraction steam pressure, the low-pressure heater side extraction steam inlet pressure and the pipe resistance characteristic coefficient. The steam turbine low-pressure cylinder extraction steam pressure, the low-pressure heater side extraction steam inlet pressure and the pipe resistance characteristic coefficient are included in the flow characteristic equation of the extraction steam pipe. That is, the steam heat release model and the condensate heat absorption model (low-pressure heater condensate and extraction steam dynamic heat exchange model based on the moving boundary method) need to be coupled with the flow characteristic equation of the extraction steam pipe for solution.

[0077] In addition, the result of the frequency modulation simulation is the steam turbine power increment dynamic value, that is, the steam turbine transient work needs to be understood in terms of the extraction steam flow, that is, the steam turbine flow-power dynamic response equation needs to be involved in the joint solution.

[0078] In some embodiments, the inputting the condensate flow step signal into the pre-constructed thermal power generating unit simulation model for simulation calculation to obtain a steam turbine power increment dynamic value specifically includes:

[0079] obtaining initial parameters; wherein the initial parameters include extraction steam point initial pressure, extraction steam point initial temperature, condensate inlet temperature, condensate inlet pressure and target load;

[0080] inputting the initial parameters into the thermal power generating unit simulation model for solution to obtain steady-state parameters;

[0081] inputting the steady-state parameters and the condensate flow step signal into the thermal power generating unit simulation model for iterative solution to obtain a steam turbine power increment dynamic value.

[0082] Specifically, in the specific frequency modulation dynamic simulation process, the initial time is when the grid frequency difference exceeds the dead zone, and the end time is when the grid frequency difference returns to the dead zone. The input quantity of the simulation as a whole is the condensate flow step signal, and the output result is the dynamic value of the turbine power increment. The known quantities are the grid frequency difference curve of the entire frequency modulation process, the initial pressure and temperature of the extraction point, the condensate inlet temperature and pressure, etc.

[0083] In the solving process, the steady-state parameters are first solved. In this process, the focus is to find the equilibrium point, i.e., to make the non-steady-state terms of each equation of the thermal power unit simulation model zero. In the actual operation process, the initial parameters including the target load are input into the thermal power unit simulation model, and the steady-state parameters of each equation of the thermal power unit simulation model are solved. It should be pointed out that the target load can be any load value of the current thermal power unit, and the present application does not limit this.

[0084] Then, the dynamic process is solved. The steady-state parameters and the condensate flow step signal are input into each equation of the thermal power unit simulation model for iterative solving, and finally the dynamic value of the turbine power increment is obtained.

[0085] In some embodiments, the steady-state parameters and the condensate flow step signal are input into the thermal power unit simulation model for iterative solving to obtain the dynamic value of the turbine power increment, specifically including:

[0086] S1: input the steady-state parameters and the initial value of the condensate flow step signal into the thermal power unit simulation model to obtain the parameter value at the initial time;

[0087] S2: input the parameter value at the initial time into the thermal power unit simulation model to obtain a target iteration formula; the target iteration formula includes a turbine power iteration equation at the current time and the previous time;

[0088] S3: set the turbine power at the current time step as a hypothetical value, solve the current solving equation according to the hypothetical value, verify the solving result by substituting it into the property equation of the supercooling section, and if the equation is correct, record the hypothetical value and jump to step S4; if the equation is not correct, update the hypothetical value according to the pre-set power value iteration rule, and repeat step S3; wherein the current solving equation includes the steam heat release model of the superheating section, the steam heat release model, the steam heat release model of the two-phase section, and the mass and energy conservation equations of the supercooling section;

[0089] S4: add one to the current time step, repeat steps S3-S4, until the turbine power curve obtained according to the hypothetical value meets the pre-set ending condition, and obtain the dynamic value of the turbine power increment according to the turbine power curve.

[0090] Specifically, as shown in FIG. 2, the method includes the following steps:

[0091] In step S1, the condensate pump frequency change value (condensate flow step signal initial value) and the initial steady-state operation parameter value (steady-state parameter) are first input to the thermal power generating unit simulation model to determine the initial time parameter value, including the initial time node condensate temperature and pressure. It needs to be noted that the input condensate pump frequency change value is used as a boundary condition in the calculation.

[0092] In step S2, the initial time low-pressure heater node temperature and pressure value are input to the thermal power generating unit simulation model to obtain the target iteration formula of t and (t-1).

[0093] In step S3, the equation set at t1 time (current time step) is solved. First, the p value of the current step is assumed to be a hypothetical value, and the current solving equation is solved according to the assumed p value of the current step. The current solving equation includes all formulas in the superheated region, all formulas in the two-phase region, and the mass conservation and energy conservation formulas in the subcooled section. The solving result includes the average condensate temperature. The obtained average condensate temperature is substituted into the subcooled section heat exchange formula (and the condensate heat exchange formula) to determine whether it is correct. If it is correct, it enters the (t+1) step, otherwise, according to the power value iteration rule, the step S3 is repeated.

[0094] It needs to be noted that the power value iteration rule determines the direction. The p value is calculated step by step in the large and small directions. The direction is determined by which one is closer to 0. This is repeated 100 times until the heat exchange formula is less than 0.001.

[0095] In step S4, the (t+1) step is entered, and the dynamic curve p(i)-i and min(i)-i curve are finally obtained, and the steam turbine power curve and the steam turbine power increment dynamic value are obtained. Wherein, i is the time, p(i)-i curve is the change curve of pressure (p) with time at each time, and min(i)-i curve is the change curve of steam turbine inlet flow (min) with time at each time.

[0096] Based on the above embodiment, in some embodiments, the above solving process can also be simplified in combination of one or more of the following ways:

[0097] 1) Use interpolation method instead of refprop to realize mathematical formula solving instead of table lookup;

[0098] 2) Use mathematica to reduce numerical rounding error;

[0099] 3) Use explicit iteration format.

[0100] The application provides a primary frequency modulation dynamic simulation method based on a condensate throttling strategy of thermal power, which comprises the following steps: according to the extraction steam aggregation state of the heat exchange process of cold and hot fluids of the thermal power unit, a steam heat release model and a condensate heat absorption model are established along the flow direction of the cold and hot fluids by using a moving boundary method; a thermal power unit simulation model is obtained according to a flow characteristic equation of an extraction steam pipeline, a flow-power dynamic response equation of a steam turbine, the steam heat release model and the condensate heat absorption model; in response to the fact that the voltage frequency difference exceeds a dead zone, a condensate flow step signal is obtained, and the condensate flow step signal is input into the pre-constructed thermal power unit simulation model for simulation calculation to obtain a dynamic value of the power increment of the steam turbine. The application uses the moving boundary method to model the dynamic heat exchange process of the thermal power unit, and only considers one-dimensional modeling along the axial main flow direction, so that the advantages of fast and accurate simulation are achieved, and the primary frequency modulation dynamic simulation with high precision and high speed is realized.

[0101] The primary frequency modulation dynamic simulation device based on the condensate throttling strategy of thermal power provided by the application is described below, and the primary frequency modulation dynamic simulation device based on the condensate throttling strategy of thermal power described below can be correspondingly referred to the primary frequency modulation dynamic simulation method based on the condensate throttling strategy of thermal power described above. As shown in FIG. 3, the device comprises:

[0102] The model unit 310 is configured to: according to the extraction steam aggregation state of the heat exchange process of cold and hot fluids of the thermal power unit, establish a steam heat release model and a condensate heat absorption model along the flow direction of the cold and hot fluids by using a moving boundary method; and obtain a thermal power unit simulation model according to a flow characteristic equation of an extraction steam pipeline, a flow-power dynamic response equation of a steam turbine, the steam heat release model and the condensate heat absorption model.

[0103] The simulation unit 320 is configured to: in response to the fact that the voltage frequency difference exceeds a dead zone, obtain a condensate flow step signal, input the condensate flow step signal into the pre-constructed thermal power unit simulation model for simulation calculation, and obtain a dynamic value of the power increment of the steam turbine.

[0104] According to the primary frequency modulation dynamic simulation device based on the condensate throttling strategy of thermal power provided by the application, the extraction steam aggregation state of the heat exchange process of cold and hot fluids of the thermal power unit is used to establish a steam heat release model and a condensate heat absorption model along the flow direction of the cold and hot fluids by using a moving boundary method, and the modeling process specifically comprises the following steps:

[0105] According to the parameter changes of the cold and hot fluids along the flow direction in the heat exchange process, the heat exchange process is divided into a superheating section, a two-phase section and a subcooling section, and the lengths of the superheating section, the two-phase section and the subcooling section are set as variables related to time;

[0106] An energy conservation equation, a mass conservation equation and a property equation of steam heat release in the superheating section, the two-phase section and the supercooling section are sequentially constructed to obtain a steam heat release model; an energy conservation equation, a mass conservation equation and a property equation of condensate heat absorption in the superheating section, the two-phase section and the supercooling section are sequentially constructed to obtain a condensate heat absorption model.

[0107] According to the application, a dynamic simulation device for primary frequency modulation based on a condensate throttling strategy of thermal power is provided.

[0108] An initial parameter is obtained; the initial parameter includes an initial pressure of a steam extraction point, an initial temperature of the steam extraction point, an inlet temperature of condensate, an inlet pressure of the condensate and a target load;

[0109] The initial parameter is input into the thermal power unit simulation model for solving to obtain a steady-state parameter;

[0110] The steady-state parameter and the condensate flow step signal are input into the thermal power unit simulation model for iterative solving to obtain a dynamic value of steam turbine power increment.

[0111] According to the application, a dynamic simulation device for primary frequency modulation based on a condensate throttling strategy of thermal power is provided.

[0112] S1: the steady-state parameter and the initial value of the condensate flow step signal are input into the thermal power unit simulation model to obtain a parameter value at an initial time;

[0113] S2: the parameter value at the initial time is input into the thermal power unit simulation model to obtain a target iteration formula; the target iteration formula includes a steam turbine power iteration equation at a current time and a previous time;

[0114] S3: a steam turbine power at a current time step is set as a hypothetical value, the current solving equation is solved according to the hypothetical value, the solving result is substituted into a property equation of the supercooling section for verification, the equation is established to record the hypothetical value and jump to step S4; the equation is not established to update the hypothetical value according to a pre-set power value iteration rule and repeat step S3; the current solving equation includes the steam heat release model and the steam heat release model of the superheating section, the steam heat release model and the steam heat release model of the two-phase section, and the mass conservation and energy conservation equations of the supercooling section;

[0115] S4: add one to the current time step, repeat steps S3-S4 until a preset ending condition is met according to the steam turbine power curve obtained according to the assumed value, and obtain a steam turbine power increment dynamic value according to the steam turbine power curve.

[0116] According to the application, a dynamic simulation device for primary frequency modulation based on a condensate throttling strategy of thermal power is provided, and the steam heat release model comprises:

[0117] The superheating section comprises:

[0118] Wherein, p h1s is the average density of the superheating section, u h1s is the average flow velocity of the superheating section, t is time, x is the distance along the flow direction, h h1s is the average enthalpy of the superheating section, P h1s is the average pressure of the superheating section, k h1s is the average heat transfer coefficient of the superheating section, T h1s is the average temperature of the superheating section, T c,h1s is the average temperature of the condensate section corresponding to the extraction steam of the superheating section, D is the pipe diameter, A is the heat exchange area of the condensate and the extraction steam, p 1s is the density of the superheating section at the inlet, u 1s is the flow velocity of the superheating section at the inlet, h h1s is the enthalpy of the superheating section at the inlet, P 1s is the pressure of the superheating section at the inlet, T 1s is the temperature of the superheating section at the inlet.

[0119] The two-phase section comprises:

[0120] Wherein, p h2 is the average density of the two-phase section, u h2 is the average flow velocity of the two-phase section, t is time, x is the distance along the flow direction, h h2 is the average enthalpy of the two-phase section, P h2 is the average pressure of the two-phase section, k h2 is the average heat transfer coefficient of the two-phase section, T h2 is the average temperature of the two-phase section, T c,h2 is the average temperature of the condensate section corresponding to the extraction steam of the superheating section, D is the pipe diameter, A is the heat exchange area of the condensate and the extraction steam, p sl is the density of the saturated steam, l is the dryness, p sv is the density of the saturated water, h sl is the enthalpy of the saturated steam.

[0121] The subcooling section comprises:

[0122] Wherein, p h1vis the average value of the density of the supercooling section, u h1v is the average value of the flow velocity of the supercooling section, τ is time, and x is the distance along the flow direction, k h1v is the average value of the enthalpy of the supercooling section, P h1v is the average value of the pressure of the supercooling section, k h1v is the average value of the heat exchange coefficient of the supercooling section, T h1v is the average value of the temperature of the supercooling section, T c,h1v is the average temperature of the condensate section corresponding to the extraction steam of the supercooling section, D is the pipe diameter, and A is the heat exchange area of the condensate and the extraction steam.

[0123] According to the power plant condensate throttling strategy-based primary frequency modulation dynamic simulation device provided in the application, the condensate heat absorption model comprises:

[0124] wherein ρ c is the average value of the density of the condensate corresponding to the extraction steam of the supercooling, two-phase and superheating sections, u c is the average value of the flow velocity of the condensate corresponding to the extraction steam of the supercooling, two-phase and superheating sections, τ is time, and x is the distance along the flow direction, k c is the average value of the heat exchange coefficient of the condensate corresponding to the extraction steam of the supercooling, two-phase and superheating sections, T c is the average value of the temperature of the condensate corresponding to the extraction steam of the supercooling, two-phase and superheating sections, c p is the average value of the specific heat capacity of the condensate corresponding to the extraction steam of the supercooling, two-phase and superheating sections, T h2 is the average value of the temperature of the two-phase section, T h1v is the average value of the temperature of the supercooling section, T h1s is the average value of the temperature of the superheating section, D is the pipe diameter, and A is the heat exchange area of the condensate and the extraction steam.

[0125] The power plant condensate throttling strategy-based primary frequency modulation dynamic simulation device provided in the application establishes a steam heat release model and a condensate heat absorption model along the flow direction of the cold and hot fluids by using the moving boundary method according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the power plant unit; obtains a power plant unit simulation model according to a pre-constructed extraction steam pipeline flow characteristic equation, a pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model and the condensate heat absorption model; obtains a steam turbine power increment dynamic value by inputting a condensate flow step signal to the pre-constructed power plant unit simulation model for simulation calculation in response to the voltage frequency difference exceeding a dead zone. The application models the dynamic heat exchange process of the power plant unit by using the moving boundary method, and only considers one-dimensional modeling along the axial main flow direction, has the advantages of fast and accurate simulation, and realizes high-precision and fast frequency modulation dynamic simulation.

[0126] Figure 4 illustrates an entity structure diagram of an electronic device, as shown in Figure 4, 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, the memory 430 complete the mutual communication through the communications bus 440. The processor 410 can call the logic instruction in the memory 430 to execute the dynamic simulation method of the primary frequency modulation based on the fire power condensate throttling strategy, the method comprises: according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the fire power unit, the steam heat release model and the condensate heat absorption model are established along the flow direction of the cold and hot fluid by using the moving boundary method; according to the pre-constructed flow characteristic equation of the extraction steam pipeline, the pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model and the condensate heat absorption model, the fire power unit simulation model is obtained; in response to the voltage frequency difference exceeding the dead zone, the condensate flow step signal is obtained, the condensate flow step signal is input to the pre-constructed fire power unit simulation model for simulation calculation, and the steam turbine power increment dynamic value is obtained.

[0127] In addition, the logic instruction in the memory 430 described above can be realized in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product stored in a storage medium includes a plurality of instructions for making a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk and various program code storage media.

[0128] In another aspect, the present application also provides a computer program product comprising a computer program, which 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 perform the method for dynamic simulation of primary frequency modulation based on the throttling strategy of condensate water of thermal power, which comprises: according to the extraction steam aggregation state of the heat exchange process of cold and hot fluids of the thermal power unit, establishing steam heat release models and condensate water heat absorption models along the flow direction of the cold and hot fluids by using the moving boundary method; obtaining a thermal power unit simulation model according to the pre-constructed flow characteristic equation of the extraction steam pipeline, the pre-constructed flow-power dynamic response equation of the steam turbine, the steam heat release models and the condensate water heat absorption models; in response to the voltage frequency difference exceeding the dead zone, obtaining a condensate water flow step signal, inputting the condensate water flow step signal into the pre-constructed thermal power unit simulation model for simulation calculation, and obtaining a dynamic value of the power increment of the steam turbine.

[0129] In another aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program can be executed by a processor to implement the method for dynamic simulation of primary frequency modulation based on the throttling strategy of condensate water of thermal power, which comprises: according to the extraction steam aggregation state of the heat exchange process of cold and hot fluids of the thermal power unit, establishing steam heat release models and condensate water heat absorption models along the flow direction of the cold and hot fluids by using the moving boundary method; obtaining a thermal power unit simulation model according to the pre-constructed flow characteristic equation of the extraction steam pipeline, the pre-constructed flow-power dynamic response equation of the steam turbine, the steam heat release models and the condensate water heat absorption models; in response to the voltage frequency difference exceeding the dead zone, obtaining a condensate water flow step signal, inputting the condensate water flow step signal into the pre-constructed thermal power unit simulation model for simulation calculation, and obtaining a dynamic value of the power increment of the steam turbine.

[0130] The device embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0131] Those skilled in the art can clearly understand the technical solutions of the various embodiments from the above description of the embodiments, and the various embodiments can be implemented by means of software with the necessary general hardware platforms, and of course can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, 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, and the like, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0132] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than 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 for some technical features therein; 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 method for dynamic simulation of primary frequency modulation based on throttling strategy of condensate water of thermal power, applied to thermal power unit, characterized in that, The method comprises the following steps: According to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, a steam heat release model and a condensate water heat absorption model are established along the flow direction of the cold and hot fluid by using a moving boundary method; a thermal power generating unit simulation model is obtained according to a pre-constructed flow characteristic equation of the extraction steam pipeline, a pre-constructed flow-power dynamic response equation of the steam turbine, the steam heat release model and the condensate water heat absorption model; In response to the voltage frequency difference exceeding a dead zone, a condensate water flow step signal is obtained, and the condensate water flow step signal is input into the pre-constructed thermal power generating unit simulation model for simulation calculation to obtain a steam turbine power increment dynamic value.

2. The method of claim 1, wherein the method is based on a throttling strategy of thermal power condensate water. The method according to the extraction steam aggregation state of the cold and hot fluid heat exchange process of the thermal power generating unit, and the steam heat release model and the condensate water heat absorption model are established along the flow direction of the cold and hot fluid by using a moving boundary method, specifically comprising: According to the parameter changes of the cold and hot fluid along the flow direction in the heat exchange process, the heat exchange process is divided into a superheating section, a two-phase section and a subcooling section, and the lengths of the superheating section, the two-phase section and the subcooling section are set as variables with respect to time; The energy conservation, mass conservation and property equation of steam heat release in the superheating section, the two-phase section and the subcooling section are sequentially constructed to obtain a steam heat release model; the energy conservation, mass conservation and property equation of condensate water heat absorption in the superheating section, the two-phase section and the subcooling section are sequentially constructed to obtain a condensate water heat absorption model.

3. The method of claim 2, wherein the throttling strategy is based on condensate of thermal power. The method of inputting the condensate water flow step signal into the pre-constructed thermal power generating unit simulation model for simulation calculation to obtain a steam turbine power increment dynamic value, specifically comprising: Obtaining initial parameters; wherein the initial parameters include extraction steam point initial pressure, extraction steam point initial temperature, condensate water inlet temperature, condensate water inlet pressure and target load; Inputting the initial parameters into the thermal power generating unit simulation model for solving to obtain steady-state parameters; Inputting the steady-state parameters and the condensate water flow step signal into the thermal power generating unit simulation model for iterative solving to obtain a steam turbine power increment dynamic value. The method of inputting the steady-state parameters and the condensate water flow step signal into the thermal power generating unit simulation model for iterative solving to obtain a steam turbine power increment dynamic value, specifically comprising:

4. The method of claim 3, wherein the throttling strategy is based on condensate throttling of a thermal power plant. S1: inputting the steady-state parameters and the initial value of the condensate water flow step signal into the thermal power generating unit simulation model to obtain parameter values at an initial time; S2: inputting the parameter values at the initial time into the thermal power generating unit simulation model to obtain a target iteration formula; the target iteration formula comprises a steam turbine power iteration equation at a current time and a previous time. ​ S3: set the steam turbine power of the current time step as a hypothetical value, solve the current solving equation according to the hypothetical value, substitute the solving result into the property equation of the supercooling section to verify, if the equation is established, record the hypothetical value and jump to step S4; if the equation is not established, update the hypothetical value according to the pre-set power value iteration rule, and repeat step S3; wherein the current solving equation includes the steam heat release model and the steam heat release model of the superheating section, the steam heat release model and the steam heat release model of the two-phase section, and the mass conservation and energy conservation equation of the supercooling section; S4: add one to the current time step, repeat steps S3-S4, until the steam turbine power curve obtained according to the hypothetical value meets the pre-set ending condition, and obtain the steam turbine power increment dynamic value according to the steam turbine power curve.

5. The method of claim 1 or 2, wherein the method is characterized by, The steam heat release model includes: superheating section: where p h1s is the average value of the density in the superheating section, u h1s is the average value of the flow velocity in the superheating section, t is time, x is the distance along the flow direction, h h1s is the average value of the enthalpy in the superheating section, p h1s is the average value of the pressure in the superheating section, k h1s is the average value of the heat transfer coefficient in the superheating section, T h1s is the average value of the temperature in the superheating section, and T c,h1s The average temperature of the condensate section corresponding to the two-phase extraction steam, D is the pipe diameter, A is the heat exchange area of the condensate water and the extraction steam, and p 1s is the inlet value of the superheating section density, u 1s is the inlet value of the superheating section flow rate, h h1s is the inlet value of the superheating section enthalpy, P 1s is the inlet value of the superheating section pressure, T 1s is the inlet value of the superheating section temperature; Two-phase section: wherein p h2 is the average value of the density of the two-phase section, u h2 is the average value of the flow rate of the two-phase section, t is time, x is the distance along the flow direction, h h2 is the average value of the enthalpy of the two-phase section, p h2 is the average value of the pressure of the two-phase section, k h2 is the average value of the heat exchange coefficient of the two-phase section, T h2 is the average value of the temperature of the two-phase section, T c,h2 is the average temperature of the condensate section corresponding to the extraction steam of the superheating section, D is the pipe diameter, A is the heat exchange area of the condensate and the extraction steam, p sl is the density value of the saturated steam, l is the dryness, p sv is the density value of the saturated water, h sl is the enthalpy value of the saturated steam; Subcooling section: wherein p h1v is the average value of the subcooled section density, u h1v is the average value of the subcooled section flow rate, t is time, x is the distance along the flow direction, h h1v is the average value of the subcooled section enthalpy, P h1v is the average value of the subcooled section pressure, k h1v is the average value of the subcooled section heat exchange coefficient, T h1v is the average value of the subcooled section temperature, T c,h1v is the average value of the condensate section temperature corresponding to the subcooled section extraction, D is the pipe diameter, and A is the heat exchange area of the condensate and the extraction.

6. The method of claim 1 or 2, wherein the method is based on a throttling strategy of thermal power condensate water. The condensate absorption model includes: wherein, p c is the average value of the condensed water density corresponding to the supercooled, two-phase, and superheated extraction steam, u c is the average value of the condensed water flow rate corresponding to the supercooled, two-phase, and superheated extraction steam, t is time, x is the distance along the flow direction, k c is the average value of the condensed water heat transfer coefficient corresponding to the supercooled, two-phase, and superheated extraction steam, T c is the average value of the condensed water temperature corresponding to the supercooled, two-phase, and superheated extraction steam, c p is the average value of the specific heat capacity of the condensed water corresponding to the supercooled, two-phase, and superheated extraction steam, T h2 is the average value of the two-phase section temperature, T h1v is the average value of the supercooled section temperature, T h1s is the average value of the superheated section temperature, D is the pipe diameter, and A is the heat exchange area of the condensed water and the extraction steam.

7. A device for dynamic simulation of primary frequency modulation based on throttling strategy of condensate water of thermal power, applied to thermal power unit, characterized in that, including: The model unit is configured to: according to the steam extraction aggregation state of the heat exchange process of the thermal power generating unit, establish a steam heat release model and a condensate water heat absorption model along the flow direction of the cold and hot fluids by using a moving boundary method; and obtain a thermal power generating unit simulation model according to a pre-constructed steam extraction pipeline flow characteristic equation, a pre-constructed steam turbine flow-power dynamic response equation, the steam heat release model and the condensate water heat absorption model. The simulation unit is configured to: in response to the voltage frequency difference exceeding the dead zone, acquire a condensate water flow step signal, input the condensate water flow step signal into the pre-constructed thermal power generating unit simulation model to perform simulation calculation, and obtain a steam turbine power increment dynamic value.

8. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the primary frequency modulation dynamic simulation method based on the thermal power condensate water throttling strategy according to any one of claims 1 to 6. 9.A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the primary frequency modulation dynamic simulation method based on the thermal power condensate water throttling strategy according to any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to implement the primary frequency modulation dynamic simulation method based on the thermal power condensate water throttling strategy according to any one of claims 1 to 6.

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