Simulation method and system for realizing dynamic peak regulation simulation of thermal power generating unit

Abstract

The invention discloses a simulation method and system for realizing dynamic peak regulation simulation of a thermal power generating unit. The method comprises the following steps: building a simulation model of the thermal power generating unit in process simulation software; inputting a basic parameter of the thermal power generating unit in a steady state as a peak regulation basic value; the programming software reads root files of all unit assemblies of the thermal power generating unit in the process simulation software, constructs and trains a steam turbine stage rear output parameter prediction model, and predicts the outlet pressure and the outlet temperature of a corresponding steam turbine; the programming software returns the outlet pressure and the outlet temperature of each stage of steam turbine to the process simulation software to obtain the output power of the corresponding steam turbine so as to obtain the steam extraction amount required by the steam turbine and further obtain the steam flow input into the inlet of the next stage of steam turbine; and so on, until the output power of the thermal power generating unit reaches the target peak adjustment value. The simulation precision is improved, and the simulation difficulty is reduced.

Description

Technical Field

[0001] The present invention relates to the field of peak shaving simulation of thermal power units, and particularly to a simulation method and system for realizing dynamic peak shaving simulation of thermal power units. Background Art

[0002] With the transformation of the global energy structure and the improvement of environmental protection requirements, thermal power units, as an important part of the power system, have received unprecedented attention for their operating flexibility and peak shaving ability. In the power market, thermal power units not only need to ensure the stability of power supply, but also need to respond to the peak shaving demands of the power grid to adapt to the volatility of clean energy such as wind power and solar energy. The peak shaving ability of thermal power units is directly related to the operating safety and economy of the power grid. Therefore, improving the peak shaving efficiency and flexibility of thermal power units has become an important topic in the power industry.

[0003] In this context, the coupled molten salt system, as an efficient heat storage technology, has been introduced into thermal power units to enhance their peak shaving ability. The molten salt system can store thermal energy during the low-demand period of electricity and release thermal energy during the peak period, realizing the temporal and spatial transfer of thermal energy, thereby improving the operating flexibility of thermal power units. However, existing dynamic peak shaving process simulation methods often ignore the influence of the extraction process on the changes in the output parameters (steam temperature and pressure at the outlets of each stage) of the steam turbine during modeling, which results in inaccurate calculation of the output power of the steam turbine in previous studies.

[0004] The invention patent (CN 118822024 A) discloses a modeling and operation strategy optimization method for a heat supply unit coupled with molten salt heat storage. This method faces challenges in the exothermic efficiency fluctuation of the molten salt heat storage system and the maintenance of system stability during actual operation, and needs to be further optimized to improve the robustness of the system.

[0005] The invention patent (CN 118709349 A) discloses a refined modeling method and system for variable operating conditions of a heat supply unit, which involves constructing component models based on physical models, connecting components to build an overall thermal system model, obtaining a simulation model of the heat supply unit under rated conditions, and calculating the characteristic curves of important components under deep peak shaving conditions. This method requires a large amount of measured data support during actual application, and the determination of model parameters may be relatively complex, increasing the implementation difficulty.

[0006] The invention patent (CN 117031950 A) describes a method and device for modeling a deep peak shaving thermal power unit control system. This method obtains historical operation data from the plant-level monitoring information system of the unit, constructs a deep peak shaving thermal power unit system model based on data-driven and machine learning, and realizes short-term prediction of the data of the pressure after the regulating stage and the load within a certain period in the future. However, this method has the problem that the model prediction accuracy is limited by the quality of historical data, and in practical applications, the model may need to be updated frequently to adapt to the changes in the unit operation state.

[0007] In summary, the existing technologies have limitations in the dynamic peak shaving simulation of thermal power units. For example, they fail to fully consider the impact of extraction steam on the output parameters of steam turbines, rely on a large amount of measured data, and have frequent model updates. These problems limit the accuracy and practicality of the dynamic peak shaving simulation of thermal power units. Summary of the Invention

[0008] Aiming at the problems existing in the prior art, such as insufficient accuracy, strong dependence on measured data, complex determination of model parameters, and high cost of model update and maintenance, the present invention proposes a simulation method and system for realizing the dynamic peak shaving simulation of thermal power units. Using Aspen Plus and MATLAB software, a simulation system and method for dynamically peak shaving the coupled molten salt system of thermal power units are realized. This method can meet the prediction of the real-time output parameters of steam turbines after the change of the extraction steam volume during the operation of thermal power units, so as to correctly calculate the real-time output power of steam turbines, and can also incorporate the returned steam of the heat storage system back into the system iterative cycle for calculation, realizing the efficient coupling of thermal power units and molten salt systems.

[0009] The specific technical solutions are as follows:

[0010] A simulation method for realizing the dynamic peak shaving simulation of thermal power units, including the following steps:

[0011] S1: Build a simulation model of a thermal power unit in a process simulation software; the thermal power unit includes: a boiler, a steam turbine unit, a condenser, a high-pressure heater, and a low-pressure heater; the high-temperature and high-pressure steam output by the boiler is extracted and input into the steam turbine unit to drive the steam turbine to do work; the low-temperature and low-pressure steam discharged by the steam turbine unit is input into the condenser to become condensate, and the condensate is heated by the low-pressure heater and the high-pressure heater in sequence and then returned to the boiler, and the low-pressure heater and the high-pressure heater use the extraction steam of the steam turbine for heating;

[0012] S2: Input the basic parameters of the thermal power unit in the steady state in the process simulation software and use them as the peak shaving base value;

[0013] S3: The programming software reads the root files of each unit component of the thermal power unit in the process simulation software;

[0014] S4: Build and train a prediction model for the output parameters of the steam turbine stage in the programming software. The output parameters include the outlet pressure and outlet temperature. After training, based on the input data of each stage of the steam turbine in the thermal power unit after extraction, predict the outlet pressure and outlet temperature of the corresponding steam turbine.

[0015] S5: The programming software returns the outlet pressure and outlet temperature of each stage of the steam turbine to the process simulation software to obtain the output power of the corresponding steam turbine. Combine the terminal difference of the high-pressure heater or the terminal difference of the low-pressure heater in the basic parameters to calculate the internal steam extraction amount required for the thermal power unit of this steam turbine, so as to obtain the steam flow rate entering the inlet of the next stage of the steam turbine. According to the output power of each stage of the steam turbine, obtain the output power of the thermal power unit.

[0016] S6: Continuously change the external steam extraction amount of the thermal power unit, and then change the input data of each stage of the steam turbine in the thermal power unit after extraction until the output power of the thermal power unit reaches the target peak regulation value.

[0017] Further, the thermal power unit is also coupled with a molten salt energy storage system, which includes: a hot salt tank, a cold salt tank, a steam-molten salt heat exchanger, a molten salt-steam heat exchanger, and a molten salt pump. The input steam end of the steam-molten salt heat exchanger is the extracted high-temperature and high-pressure steam output by the boiler. The molten salt inlet is connected to the cold salt tank through a molten salt pump, the molten salt outlet is connected to the hot salt tank, and the steam outlet outputs the heat-exchanged steam and returns it to the thermal power unit. The water inlet end of the molten salt-steam heat exchanger inputs part of the condensate water. The molten salt inlet is connected to the hot salt tank through a molten salt pump, the molten salt outlet is connected to the cold salt tank, and the steam outlet outputs the heat-exchanged steam and returns it to the thermal power unit. The connections of the steam-molten salt heat exchanger and the molten salt-steam heat exchanger to the thermal power unit are controlled by valves for on-off.

[0018] The S1 also includes building a simulation model of the steam-molten salt heat exchanger and a model of the molten salt-steam heat exchanger in the programming software to obtain the temperature changes of the molten salt and steam in the two heat exchangers during the heat exchange process. During the execution of S6, return the parameter information of the two heat exchangers under different peak regulation requirements to the process simulation software. The parameter information includes temperature parameters, steam flow rate, and outlet pressure.

[0019] Further, the process simulation software selects Aspen Plus, and the programming software selects MATLAB. Use Active X technology to build a data interface between Aspen Plus and MATLAB to achieve data transmission.

[0020] Further, the S1 is implemented through the following sub-steps:

[0021] (1) Selection of physical property methods: Input the components appearing in all input streams, including: fuel, air, water or steam; Select the PENG-ROB local physical property method for the components of fuel and air, and select the STEAM-TA global physical property method for the components involving water or steam;

[0022] (2) Select the corresponding unit components in Aspen Plus, and build its simulation model according to the heat balance diagram of the thermal power unit under the basic operating conditions.

[0023] Furthermore, in S2, the basic parameters include: the parameters of the high-temperature and high-pressure steam output by the boiler, the extraction steam pressures of each stage group of the steam turbine, the terminal differences of the high-pressure heaters, the terminal differences of the low-pressure heaters, the fuel input, and the makeup water; The parameters of the high-temperature and high-pressure steam output by the boiler include the outlet flow rate, pressure, and temperature; The basic parameters are obtained according to the heat balance diagram of the thermal power unit under the basic operating conditions.

[0024] Furthermore, in S4, the prediction model of the output parameters after the steam turbine stage uses a support vector regression model. The historical operation data of each stage of the steam turbine of the thermal power unit under various operating conditions are standardized and used as the training data set. The historical operation data include: the flow rate, inlet pressure and temperature, and outlet pressure and temperature of a single-stage steam turbine; Use the training data set to train the support vector regression model to realize the prediction of the outlet pressure and outlet temperature.

[0025] Furthermore, in the modeling process of the steam-salt heat exchanger simulation model and the salt-steam heat exchanger model, the following assumptions are made: (1) Assume that there is no heat transfer loss in the heat exchanger; (2) Assume that there is no temperature cross in the heat transfer process; (3) Assume that the flow states of steam and molten salt are uniform, and all parameters are consistent in space, that is, consistent on the cross-section of the pipeline.

[0026] Furthermore, when building the steam-salt heat exchanger simulation model, first calculate the velocity of steam using the steam flow rate and molten salt flow rate. The expression is as follows:

[0027]

[0028] In the formula, V steam represents the velocity of steam, m steam represents the mass flow rate of steam, ρ steam represents the density of steam, obtained by calling the Refprop material database, A steam represents the cross-sectional area of the pipeline; D represents the inner diameter of the pipeline;

[0029] Calculate the heat transfer coefficient U through the Reynolds number Re steam 、Prandtl number Pr steam and Nusselt number Nu steam The expression is as follows:

[0030]

[0031] Wherein, μ steam is the dynamic viscosity of steam, c steam is the specific heat capacity of steam, k steam is the thermal conductivity of steam, and all three are obtained by calling the Refprop material database;

[0032] The heat exchanger is discretized in space, and the heat release Q of steam in each small-section single tube and the heat absorption Q1 of molten salt in the corresponding small-section single tube during the heat exchange process are calculated. The expressions are as follows:

[0033] Q = U·D·π·dz·ΔT

[0034] Q1 = -n1·Q

[0035] ΔT = T steam -T salt

[0036] Wherein, dz is the space discretization step, ΔT is the heat exchange temperature difference between steam and molten salt, and n1 is the number of small-section single tubes in a single heat exchanger;

[0037] Time discretization is performed to calculate the changes in steam temperature T steam and molten salt temperature T salt during different moments in the heat exchange process. The temperature change expressions are as follows:

[0038]

[0039] Wherein, m salt is the mass flow rate of molten salt, c salt is the specific heat capacity of molten salt;

[0040] The integral calculation of the heat storage of molten salt is carried out to obtain the total heat storage Q salt-ex of molten salt flowing through the steam - molten salt heat exchanger at the corresponding time, so as to show the total heat that molten salt can store after extracting a specified amount of steam during the peak shaving process. The expression is as follows:

[0041] Q salt-ex = n2·∫0 end m salt ·c salt ·(T salt (i + 1)-T salt (i))dt

[0042] Wherein, n2 is the number of steam - molten salt heat exchangers;

[0043] If the molten salt after heat exchange is to be heated to a specified temperature, the molten salt is heated by an electric heater, and finally the total heat storage Q of the molten salt entering the hot salt tank is obtained. salt , and the expression is as follows:

[0044] Q E = m salt · c salt · [T salt-set - T salt (end)]

[0045] Q salt = Q salt-ex + Q E

[0046] In the formula, T salt-set represents the temperature of the molten salt after heat exchange, and T salt (end) represents the specified temperature of the molten salt;

[0047] When building the simulation model of the molten salt-steam heat exchanger, considering the phase change during the process of condensate to steam, the change in steam temperature is calculated using the enthalpy value. The change expression of the outlet enthalpy value of the steam-molten salt heat exchanger at different moments during the heat exchange process is as follows:

[0048]

[0049] In the formula, m water is the flow rate of water at the water inlet entering the steam-molten salt heat exchanger, h i+1 represents the outlet enthalpy value of the steam-molten salt heat exchanger during the (i + 1)-th step of iterative calculation, and h i represents the outlet enthalpy value of the steam-molten salt heat exchanger during the i-th step of iterative calculation.

[0050] According to the outlet enthalpy value and pressure of the molten salt-steam heat exchanger, the steam temperature at the steam outlet end of the molten salt-steam heat exchanger is obtained by calling the Refprop material database.

[0051] A simulation system for realizing the dynamic peak shaving simulation of a thermal power unit, which is used to realize the simulation method for realizing the dynamic peak shaving simulation of a thermal power unit, includes: process simulation software, and programming software that can be connected for data transmission with it; the process simulation software is used to construct the simulation model of the thermal power unit, and the programming software realizes the reading and writing of the operating parameters of the thermal power unit across platforms through the data transmission connection method, and predicts the output parameters of each stage of steam turbine of the thermal power unit through the read operating parameters, so as to complete the real-time scheduling and control of the simulation model of the thermal power unit and realize the dynamic peak shaving simulation.

[0052] Furthermore, the programming software is also used to construct models of the steam-salt heat exchanger and the salt-steam heat exchanger. The steam-salt heat exchanger is used to simulate the heat exchange process of "heating molten salt with steam extracted from a thermal power unit", and the salt-steam heat exchanger is used to simulate the heat exchange process of "heating condensate water extracted from a thermal power unit with molten salt", so as to realize the peak shaving simulation of the thermal power unit coupled with the molten salt energy storage system in combination.

[0053] The beneficial effects of the present invention are as follows:

[0054] (1) The proposal of the present invention can combine the professional chemical process simulation ability of the process simulation software with the powerful numerical calculation and regulation ability of the programming software, realizing the dynamic simulation process of using the programming software to mobilize the process simulation software to complete the extraction steam energy storage of the thermal power unit. Compared with the prior art, through this innovative means, the present invention expands the modeling scope of the thermal power unit and the molten salt energy storage system, improves the accuracy and efficiency of modeling, solves the limitations of single-software modeling in the traditional technology, and reduces the system maintenance cost and operation complexity.

[0055] (2) The present invention can predict the steam parameters after each stage of the steam turbine unit during the extraction steam change process. Compared with the prior art, by introducing a dynamic modeling and prediction mechanism, the present invention improves the response speed and accuracy to the change of steam parameters, solves the problem that it is difficult to predict the steam parameter fluctuation in real time in the traditional technology, and improves the efficiency and flexibility of the peak shaving decision-making.

[0056] (3) The present invention can monitor the output power of the thermal power unit in real time and realize the peak shaving of the thermal power unit by dynamically adjusting the extraction steam volume. Compared with the prior art, through more accurate PID regulation, the present invention solves the problem of poor regulation accuracy in the traditional technology, thereby improving the flexibility and operation efficiency of the unit. Description of the Drawings

[0057] Figure 1 is a schematic structural diagram of the thermal power unit and the molten salt energy storage coupling system in the embodiment of the present invention.

[0058] Figure 2 is a flow chart of the simulation system for realizing cross-platform control of the dynamic peak shaving simulation of the thermal power unit in the embodiment of the present invention.

[0059] Figure 3 is a comparison schematic diagram of the designed output power and the simulated output power of the thermal power unit in the embodiment of the present invention.

[0060] Figure 4 is a schematic diagram of the change of the output power during the peak shaving of the thermal power unit and the molten salt energy storage coupling system in the embodiment of the present invention.

[0061] In the figure, there are a hot salt tank 1, a cold salt tank 2, an electric heater 3, a steam-salt heat exchanger 4, a salt-steam heat exchanger 5, a boiler 6, a high-pressure steam turbine unit 7, an intermediate-pressure steam turbine unit 8, a low-pressure steam turbine unit 9, a condenser 10, a deaerator 11, a first high-pressure heater 12-1, a second high-pressure heater 12-2, a third high-pressure heater 12-3, a first low-pressure heater 13-1, a second low-pressure heater 13-2, a third low-pressure heater 13-3, a flow valve 14, a molten salt pump 15, a first steam extraction valve 16-1, a second steam extraction valve 16-2, a first condensate extraction valve 17-1, a second condensate extraction valve 17-2, a first steam return point 18-1, a second steam return point 18-2, a third steam return point 18-3, a fourth steam return point 18-4, and a water pump 19. Detailed implementation manners

[0062] The present invention will be described in detail below according to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become more apparent. The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0063] A simulation system for realizing dynamic peak shaving simulation of a thermal power unit includes process simulation software and programming software capable of data transmission connection with it. The process simulation software is used to construct a simulation model of the thermal power unit. The programming software reads and writes the operating parameters of the thermal power unit across platforms through data transmission connection, and predicts the output parameters of each stage of the steam turbine of the thermal power unit based on the read operating parameters, so as to complete the real-time scheduling and control of the simulation model of the thermal power unit and realize dynamic peak shaving simulation.

[0064] Furthermore, the programming software is also used to construct models of the steam-salt heat exchanger and the salt-steam heat exchanger. The steam-salt heat exchanger is used to simulate and simulate the heat exchange process of "heating molten salt with steam extracted from the thermal power unit", and the salt-steam heat exchanger is used to simulate and simulate the heat exchange process of "heating condensate water extracted from the thermal power unit with molten salt", combined with realizing the peak shaving simulation of the thermal power unit coupled with a molten salt energy storage system.

[0065] In this embodiment, the process simulation software is Aspen Plus, and the programming software capable of data transmission connection with it is the MATLAB platform. The data transmission between Aspen Plus and MATLAB adopts the Active X technology. Aspen Plus is a powerful chemical process simulation software that can model and analyze complex thermodynamic systems; while MATLAB, with its powerful numerical calculation and algorithm development capabilities, is widely used in system simulation and the implementation of optimization strategies. The present invention combines these two software to construct a simulation system for realizing the dynamic peak shaving simulation of a thermal power unit, combining the professional chemical process simulation ability of Aspen Plus with the powerful numerical calculation and regulation ability of MATLAB, and realizing the dynamic simulation process of using MATLAB to mobilize Aspen Plus to complete the extraction steam and heat storage of the thermal power unit, providing strong technical support for the operation optimization of the thermal power unit.

[0066] As Figure 1 shown, as the object to be simulated, the thermal power unit coupled with the molten salt heat storage system includes a thermal power unit part and a molten salt heat storage part. The thermal power unit part includes: a boiler 6, a high-pressure steam turbine unit 7, a medium-pressure steam turbine unit 8, a low-pressure steam turbine unit 9, a condenser 10, a deaerator 11, high-pressure heaters, low-pressure heaters, a flow valve 14, a first extraction steam valve 16-1, a second extraction steam valve 16-2, a first water extraction valve 17-1, a second water extraction valve 17-2, and a water pump 19. The molten salt heat storage part includes: a hot salt tank 1, a cold salt tank 2, an electric heater 3, a steam-molten salt heat exchanger 4, a molten salt-steam heat exchanger 5, and a molten salt pump 15. Among them, the generator is electrically connected to and supplies power to the electric heater 3, the high-pressure steam turbine unit 7, the medium-pressure steam turbine unit 8, and the low-pressure steam turbine unit 9 respectively; the hot salt tank 1 is used to store high-temperature molten salt, and the cold salt tank 2 is used to store low-temperature molten salt.

[0067] Fuel and air react in the boiler 6. The first output end of the boiler 6 is communicated with the steam inlet end of the high-pressure steam turbine unit 7 through a pipeline, and a first extraction steam valve 16-1 is arranged on this pipeline. The steam output from the first output end is denoted as the main steam; the first steam outlet end of the high-pressure steam turbine unit 7 is communicated with the first steam inlet end of the boiler 6 through a pipeline. The second output end of the boiler 6 is communicated with the steam inlet end of the medium-pressure steam turbine unit 8 through a pipeline, and a second extraction steam valve 16-2 is arranged on this pipeline. The steam output from the second output end is denoted as the reheated steam; the first steam outlet end of the medium-pressure steam turbine unit 8 is communicated with the steam inlet end of the low-pressure steam turbine unit 9 through a pipeline, and the first steam outlet end of the low-pressure steam turbine unit 9 is communicated with the input end of the condenser 10 through a pipeline.

[0068] The output end of the condenser 10 is successively communicated with the first input end of the first low-pressure heater 13-1 through the water pump 19 and the first extraction valve 17-1. The first output end of the first low-pressure heater 13-1 is communicated with the first input end of the second low-pressure heater 13-2, and the second output end is communicated with the input end of the condenser 10. The first output end of the second low-pressure heater 13-2 is communicated with the first input end of the third low-pressure heater 13-3, and the second output end is communicated with the second input end of the first low-pressure heater 13-1. The first output end of the third low-pressure heater 13-3 is communicated with the input end of the deaerator 11, and the second output end is communicated with the second input end of the second low-pressure heater 13-2. The steam outlet end of the first-stage steam turbine of the low-pressure steam turbine unit 9 is communicated with the hot-end inlet of the second low-pressure heater 13-2 through the flow valve 14, and the steam outlet end of the second-stage steam turbine is communicated with the hot-end inlet of the first low-pressure heater 13-1 through the flow valve 14. The steam outlet end of the third-stage steam turbine of the medium-pressure steam turbine unit 8 is communicated with the hot-end inlet of the third low-pressure heater 13-3 through the flow valve 14, and the steam outlet end of the second-stage steam turbine is communicated with the input end of the deaerator 11 through the flow valve 14. The second output ends of the first low-pressure heater 13-1, the second low-pressure heater 13-2, and the third low-pressure heater 13-3 are all used to return the water after heat exchange to the upper level, and finally return to the condenser 10.

[0069] The output end of the deaerator 11 is communicated with the first input end of the first high-pressure heater 12-1 through the second extraction valve 17-2. The first output end of the first high-pressure heater 12-1 is communicated with the first input end of the second high-pressure heater 12-2, and the second output end is communicated with the input end of the deaerator 11. The first output end of the second high-pressure heater 12-2 is communicated with the first input end of the third high-pressure heater 12-3, and the second output end is communicated with the second input end of the first high-pressure heater 12-1. The first output end of the third high-pressure heater 12-3 is communicated with the second steam inlet end of the boiler 6, and the second output end is communicated with the second input end of the second high-pressure heater 12-2. The steam outlet end of the first-stage steam turbine of the medium-pressure steam turbine unit 8 is communicated with the hot-end inlet of the first high-pressure heater 12-1 through the flow valve 14. The steam outlet end of the second-stage steam turbine of the high-pressure steam turbine unit 7 is communicated with the hot-end inlet of the second high-pressure heater 12-2 through the flow valve 14, and the steam outlet end of the first-stage steam turbine is communicated with the hot-end inlet of the third high-pressure heater 12-3 through the flow valve 14. The second output ends of the third high-pressure heater 12-3, the second high-pressure heater 12-2, and the third high-pressure heater 12-3 are all used to transfer the steam after heat exchange to the upper level, and finally return to the deaerator 11.

[0070] After the thermal power unit is coupled with the molten salt heat storage part, a part of the main steam is input into the steam inlet end of the steam-molten salt heat exchanger 4 through the first steam extraction valve 16-1, and a part of the reheated steam is also input into the steam inlet end of the steam-molten salt heat exchanger 4 through the second steam extraction valve 16-2. The specific steam extraction volume is controlled by the two steam extraction valves. The steam-molten salt heat exchanger 4 adopts a shell-and-tube heat exchanger, with steam entering the tube side and molten salt entering the shell side, for heating the low-temperature molten salt with hot steam. The output end of the cold salt tank 2 is connected to the molten salt inlet of the steam-molten salt heat exchanger 4 through the molten salt pump 15. The molten salt outlet of the steam-molten salt heat exchanger 4 is connected to the inlet of the electric heater 3, and the outlet of the electric heater 3 is connected to the input end of the hot salt tank 1. The electric heater 3 is used to heat the molten salt after heat exchange to the specified temperature. After the high-temperature steam input at the steam inlet end of the steam-molten salt heat exchanger 4 exchanges heat with the molten salt, low-temperature steam is output from the steam outlet end and re-input into the thermal power unit.

[0071] The condensate pumped out by the water pump 19 is input into the molten salt-steam heat exchanger 5 through the first water extraction valve 17-1, and the water output from the deaerator 11 is also input into the water inlet end of the molten salt-steam heat exchanger 5 through the second water extraction valve 17-2. The specific input volume is controlled by the two water extraction valves. The molten salt-steam heat exchanger 5 adopts a shell-and-tube heat exchanger, with condensate entering the tube side and molten salt entering the shell side, for heating the condensate or steam with hot molten salt. The output end of the hot salt tank 1 is connected to the molten salt inlet of the molten salt-steam heat exchanger 5 through the molten salt pump 15. The molten salt outlet of the molten salt-steam heat exchanger 5 is connected to the input end of the cold salt tank 2. After the condensate or steam input at the water inlet end of the molten salt-steam heat exchanger 5 exchanges heat with the high-temperature molten salt, heat exchange steam is output from the steam outlet end and re-input into the thermal power unit.

[0072] Specifically, a part of the heat exchange steam is input into the steam inlet end of the intermediate-pressure steam turbine unit 8 from the first steam return point 18-1, and the first steam return point 18-1 is located on the connecting pipeline between the second output end of the boiler 6 and the intake end of the intermediate-pressure steam turbine unit 8. The low-temperature return steam is mixed with another part of the heat exchange steam to obtain mixed steam. The first part of the mixed steam is input into the input end of the low-pressure steam turbine unit 9 from the second steam return point 18-2, and the second steam return point 18-2 is located on the connecting pipeline between the steam outlet end of the intermediate-pressure steam turbine unit 8 and the steam inlet end of the low-pressure steam turbine unit 9; the second part of the mixed steam is input into the water pump 19 from the third steam return point 18-3, and the third steam return point 18-3 is located on the connecting pipeline between the output end of the condenser 10 and the input end of the water pump 19; the third part of the mixed steam is input into the first input end of the first high-pressure heater 12-1 from the fourth steam return point 18-4, and the fourth steam return point 18-4 is located on the connecting pipeline between the second water extraction valve 17-2 and the first input end of the first high-pressure heater 12-1; the fourth part of the mixed steam is input into the second steam inlet end of the boiler 6 from the fifth steam return point 18-5, and the fifth steam return point 18-5 is located on the connecting pipeline between the first output end of the third high-pressure heater 12-3 and the second steam inlet end of the boiler 6.

[0073] During the actual operation process, the boiler 6 in the thermal power unit heats water to generate main steam, which enters the first stage of the high-pressure steam turbine unit 7. The system extracts part of the main steam after doing work and sends it into the hot-end inlet of the high-pressure heater to heat the system return water. The steam after heat exchange returns to the deaerator 11; the remaining main steam continues to enter the next stage of the high-pressure steam turbine to do work, and so on, continuously carrying out the process of extracting steam to heat the system return water. After the main steam finishes doing work in the high-pressure steam turbine unit 7, it returns to the boiler 6 and is then heated into reheated steam. The reheated steam successively enters the intermediate-pressure steam turbine unit 8 and the low-pressure steam turbine unit 9 to do work, and correspondingly extracts part of the steam and sends it into the hot-end inlet of the low-pressure heater to heat the system return water flowing out of the condenser 10. The outlet steam of the low-pressure steam turbine unit 9 is sent into the condenser 10 to be condensed into water, which is pressurized by the water pump 19 and sent through the low-pressure heater, deaerator 11, and high-pressure heater and then re-enters the boiler 6.

[0074] In the case of only a thermal power unit, the main steam needs to extract steam through the steam extraction valve 16-1 during the process of entering the high-pressure steam turbine unit 7, and the reheated steam needs to extract steam through the steam extraction valve 16-2 to control the output power of the thermal power unit. In this case, these steams extracted to the outside of the thermal power unit have no other uses, and a large amount of energy is lost. Therefore, a method of coupling a molten salt thermal energy storage part is proposed. After coupling the molten salt thermal energy storage part, the extracted main steam and reheated steam are input into the steam inlet end of the steam-molten salt heat exchanger 4, and after heat exchange with the low-temperature molten salt, they are re-input into the thermal power unit through each steam return site, reducing the output power of the thermal power unit. Or part of the condensate water generated by the thermal power unit is input into the water inlet end of the molten salt-steam heat exchanger 5, heated to superheated steam after heat exchange with the hot molten salt, and then re-input into the intermediate-pressure steam turbine unit 8 and the low-pressure steam turbine unit 9 of the thermal power unit through each steam return site, increasing the output power of the thermal power unit.

[0075] Based on the above simulation system for realizing the dynamic peak shaving simulation of a thermal power unit, this embodiment also proposes a simulation method for realizing the dynamic peak shaving simulation of a thermal power unit, as Figure 2 shown, the method includes the following steps:

[0076] S1: In the process simulation software, build a simulation model of the thermal power unit.

[0077] In this embodiment, the process simulation software selects Aspen Plus. Building a simulation model of the thermal power unit specifically includes the following sub-steps:

[0078] (1) Selection of physical property methods: When performing process simulation, all components present in the input streams need to be input; the components present in the input streams of a thermal power unit include: fuel, air (79% N2, 21% O2), and water (steam). Further, the PENG-ROB local physical property method is selected for the components involving fuel and air, and the STEAM-TA global physical property method is selected for the components involving water (steam).

[0079] (2) Model establishment: Referring to the system composition of a 350 MW thermal power unit, corresponding unit components such as "Rstoic" (corresponding to boiler 6 in this embodiment), "Heater" (corresponding to boiler 6 in this embodiment), "HeatX" (corresponding to the high-pressure heater and low-pressure heater in this embodiment), "Compr" (corresponding to boiler 6 in this embodiment), "Pump", "Value" (corresponding to various valves in this embodiment), "Flash" (corresponding to deaerator 11 in this embodiment), etc. are selected on the Aspen Plus platform, and the entire system process is built according to the heat balance diagram of the thermal power unit under the basic operating conditions.

[0080] S2: Input the basic parameters (i.e., steady-state parameters) of the thermal power unit to obtain the output power of the thermal power unit and the operating parameters of each component at this time, and use these as the peak shaving base values. The basic parameters include: main steam parameters (including outlet flow, pressure, temperature), reheated steam parameters (including outlet flow, pressure, temperature), extraction steam pressures at all stages of the steam turbine, terminal differences of high-pressure heaters, terminal differences of low-pressure heaters, fuel input, make-up water volume, etc. These basic parameters can be obtained by referring to the heat balance diagram of the thermal power unit under the basic operating conditions.

[0081] S3: The programming software reads the root files of each unit component of the thermal power unit in the process simulation software to achieve cross-platform reading and writing of the operating parameters of the thermal power unit, thereby completing the subsequent real-time scheduling and control of the thermal power unit. In this embodiment, the programming software selects MATLAB, and uses Active X technology to build a data interface between Aspen Plus and MATLAB to achieve data transmission.

[0082] S4: In the programming software, build and train a prediction model for the output parameters after the steam turbine stage. The output parameters specifically refer to two parameters, namely the outlet pressure and outlet temperature of the steam turbine. Therefore, the prediction model for the output parameters after the steam turbine stage can be divided into an outlet pressure prediction model and an outlet temperature prediction model; the prediction model for the output parameters after the steam turbine stage only predicts the output parameters of one stage of the steam turbine in the steam turbine unit each time. Use the trained prediction model for the output parameters after the steam turbine stage to predict the corresponding outlet pressure and temperature of each stage of the steam turbine unit according to the new input data that changes for each stage of the steam turbine in the thermal power unit after extraction. This work can meet the requirement that the steam turbine can generate corresponding responses in real time when the extraction changes.

[0083] In this embodiment, both the outlet pressure prediction model and the outlet temperature prediction model use the Support Vector Regression (SVR) model to predict the outlet pressure and temperature of each stage of the steam turbine to adapt to the changing dynamic conditions after extraction. The specific implementation process is as follows: The historical operation data of each stage of the steam turbine in the thermal power unit under various conditions are standardized and used as the training data set. The standardization process is used to remove the dimensional differences and ensure the consistency of the data. The historical operation data include parameters such as the flow rate of a single-stage steam turbine (since the input and output flow rates are the same, the discussion is omitted), the inlet pressure and temperature, and the outlet pressure and temperature. Then, two SVR models are trained using different data from the training data set, which are respectively used to predict the outlet pressure and the outlet temperature. After standardizing the new input data of each stage of the steam turbine in the thermal power unit after extraction, they are respectively input into the two trained prediction models to predict the outlet pressure and temperature of the corresponding stages of the steam turbine.

[0084] S5: The programming software returns the outlet pressure and temperature of each stage of the steam turbine predicted by the steam turbine stage output parameter prediction model to the process simulation software through the data interface to obtain the output power of the corresponding single-stage steam turbine. Based on the terminal difference of the high-pressure heater or the terminal difference of the low-pressure heater in the basic parameters, the internal extraction steam volume of the thermal power unit required for this single-stage steam turbine is obtained (when the process simulation software is Aspen Plus, the extraction steam volume is calculated using the "design specification" function), so as to obtain the steam flow rate input to the inlet of the next stage of the steam turbine. Then, the output power and extraction steam volume of the next stage of the steam turbine are calculated, and so on. According to the output power of each stage of the steam turbine, the output power of the thermal power unit is obtained.

[0085] It should be noted that during the operation of the thermal power unit, there are two types of extraction: internal extraction of the thermal power unit and external extraction of the thermal power unit. The adjustment of the external extraction steam volume of the thermal power unit is used to affect the change of the output power of the thermal power unit; while the internal extraction of the thermal power unit has a relatively small extraction steam volume and is used to enter the high-pressure heater or the low-pressure heater to heat the feed water, which belongs to the basic working process of the thermal power unit.

[0086] S6: Continuously change the external extraction steam volume of the thermal power unit, and then change the input data of each stage of the steam turbine in the thermal power unit after extraction until the output power of the thermal power unit reaches the target peak regulation value, realizing the adjustment from one load to another load and from a certain operating condition to a specified condition.

[0087] Furthermore, a limit is placed on the maximum extraction steam volume. For example, the extraction steam volume does not exceed 60% of the original steam flow rate, that is, the requirements for the safe operation of the thermal power unit need to be met.

[0088] Further, when simulating and emulating the thermal power unit coupled molten salt thermal energy storage system, while executing S1, the simulation models of the steam-molten salt heat exchanger and the molten salt-steam heat exchanger are built in the programming software. During the execution of S6, the parameter information of the two heat exchanger simulation models under different peak shaving demands is returned to the process simulation software. Since peak shaving is divided into two categories: increasing load peak shaving and decreasing load peak shaving, during increasing load peak shaving, the molten salt-steam heat exchanger 5 pumps water from the condenser and heats it into steam through molten salt, and the steam returns to the thermal power unit. The information returned to the process simulation software in this state is the flow rate and temperature parameters of the reflux steam; during decreasing load peak shaving, the steam of a certain stage group of the steam turbine is extracted to the steam-molten salt heat exchanger 4 to reduce the amount of steam entering the next-stage steam turbine, thereby achieving load reduction. At this time, the returned steam generally enters a lower steam turbine unit or high-pressure heater and low-pressure heater. The information returned to the process simulation software in this state: the flow rate, temperature parameter, and pressure of the reflux steam. In summary, the parameter information includes temperature parameters, steam flow rate, and outlet steam pressure; the process simulation software performs material balance calculations (steam-water balance calculations) based on the parameter information. If the component corresponding to the steam return point is a steam turbine, the output power of the steam turbine is calculated simultaneously to achieve the peak shaving simulation of the thermal power unit coupled molten salt thermal energy storage system. This design enables the present invention to not only evaluate the impact of the molten salt thermal energy storage part on the thermal power unit, but also assist in the selection of the molten salt thermal energy storage system and the formulation of peak shaving strategies. Compared with the prior art, the present invention provides a more accurate theoretical basis for the design and operation of the molten salt thermal energy storage system, can be widely applied to the field of peak shaving and thermal energy storage of thermal power units, and has important engineering application value.

[0089] The following assumptions are made during the modeling process of the two heat exchanger simulation models: (1) It is assumed that there is no heat transfer loss in the heat exchanger; (2) It is assumed that there is no temperature cross during the heat transfer process; (3) It is assumed that the flow states of the steam and molten salt are uniform, and each parameter is consistent in space (the cross-section of the pipeline).

[0090] When modeling the steam-molten salt heat exchanger simulation model based on the above assumptions, the time-stepping and space-discretization methods are adopted, and the key parameters such as the temperature change, flow rate, and heat exchange amount of the steam and molten salt in the steam-molten salt heat exchanger 4 are calculated according to the thermodynamic principle. Specifically, it is realized through the following sub-steps:

[0091] (1.1) First, the flow velocity of the steam is calculated using the steam flow rate and the molten salt flow rate, and the expression is as follows:

[0092]

[0093] In the formula, V steam represents the flow velocity of the steam, m steam represents the mass flow rate of the steam, ρ steamdenotes the density of steam, which can be obtained by calling the Refprop material database, A steam denotes the cross-sectional area of the pipe; D denotes the inner diameter of the pipe, which depends on the heat exchanger size and can be input by the user.

[0094] The Reynolds number Re of the steam flow steam , Prandtl number Pr steam and Nusselt number Nu steam Calculate the heat transfer coefficient U, and the expression is as follows:

[0095]

[0096]

[0097] In the formula, μ steam is the dynamic viscosity of steam, c steam is the specific heat capacity of steam, k steam is the thermal conductivity of steam, and the three can also be obtained by calling the Refprop material database.

[0098] (1.2) Discretize the heat exchanger in space, and calculate the heat release Q of the steam in each small section of the single pipe and the heat absorption Q1 of the molten salt in the corresponding small section of the single pipe during the heat exchange process. The expressions are as follows:

[0099] Q = U·D·π·dz·ΔT

[0100] Q1 = -n1·Q

[0101] ΔT = T steam -T salt

[0102] In the formula, dz is the space discretization step, ΔT is the heat exchange temperature difference between steam and molten salt, and n1 is the number of small sections of single pipes in a single heat exchanger.

[0103] (1.3) Perform time discretization to calculate the changes in steam temperature T steam and molten salt temperature T salt during the heat exchange process. The specific temperature change expressions are as follows:

[0104]

[0105] In the formula, m salt is the mass flow rate of the molten salt, c salt is the specific heat capacity of the molten salt.

[0106] (1.4) Integrate the heat storage of the molten salt to obtain the total heat storage Q of the molten salt flowing through the steam-molten salt heat exchanger 4 at the corresponding time salt-ex, to show the total heat that can be stored in the molten salt after extracting a specified amount of steam during the peak shaving process, the expression is as follows:

[0107] Q salt-ex = n2·∫0 end m salt ·c salt ·(T salt (i + 1)-T salt (i))dt

[0108] In the formula, n2 is the number of steam - molten salt heat exchangers 4 in the thermal power unit coupled with the molten salt heat storage system. In this embodiment, n2 = 1.

[0109] Furthermore, if the molten salt after heat exchange is to be heated to a specified temperature, the electric heater 3 can also be used to heat the molten salt, and finally the total heat storage Q of the molten salt entering the hot salt tank 1 is obtained salt , and the expression is as follows:

[0110] Q E = m salt ·c salt ·[T salt-set -T salt (end)]

[0111] Q salt = Q salt-ex +Q E

[0112] In the formula, T salt-set represents the temperature of the molten salt after heat exchange, and T salt (end) represents the specified temperature of the molten salt.

[0113] When modeling the molten salt - steam heat exchanger simulation model based on the above assumptions, since the heat exchange process of the molten salt - steam heat exchanger is similar to that of the steam - molten salt heat exchanger, the difference is that molten salt is used to heat the condensate. It should be emphasized that the phase change during the process from condensate to steam needs to be considered in this model. Therefore, the heating of water and the temperature change should be calculated using enthalpy values. In the molten salt - steam heat exchanger simulation model, the expression for the change in the outlet enthalpy value of the steam - molten salt heat exchanger 5 at different times during the heat exchange process is as follows:

[0114]

[0115] In the formula, m water is the flow rate of water at the water inlet entering the steam - molten salt heat exchanger, h i+1 represents the outlet enthalpy value of the steam - molten salt heat exchanger during the (i + 1)-th iterative calculation, and h i represents the outlet enthalpy value of the steam - molten salt heat exchanger during the i - th iterative calculation.

[0116] In this model, the temperature at the steam outlet of the molten salt-steam heat exchanger 5 is obtained by calling the Refprop material database according to the outlet enthalpy value and pressure of the molten salt-steam heat exchanger 5.

[0117] The following examples are given to specifically illustrate the present invention.

[0118] Taking the load reduction process of a thermal power unit from the 40% THA (Turbine Heat Acceptance) operating condition to the 35% THA target condition as an example, the specific implementation process of the present invention is introduced:

[0119] First, input the basic operating parameters under the 40% THA operating condition into the simulation model of the thermal power unit built on the Aspen Plus software platform, such as: fuel input, make-up water volume, outlet flow rate, pressure, temperature, etc. of the main / reheat steam. Conduct steady-state modeling under the 40% THA operating condition, and obtain the output power of the thermal power unit and the operating parameters of each component at this time, and use this as the base value for peak shaving.

[0120] Then, through S3-S6 calculations, the extraction steam volume required for each stage of the steam turbine is obtained. Accordingly, the opening of the extraction steam valve 16-2 is adjusted through MATLAB software to change the flow rate of the extracted reheat steam, and then change the parameters such as the steam flow rate entering each steam turbine unit after the extraction steam valve 16-2; at the same time, open the connection valve between the steam-molten salt heat exchanger 4 and the thermal power unit to realize the heat exchange between steam and molten salt, thereby realizing the reduction of the output power of the thermal power unit.

[0121] Furthermore, the extraction steam parameters are sent to the steam-molten salt heat exchanger simulation model to realize the simulation of the heat exchange process of steam heating molten salt. In this model, the changes in the inlet and outlet temperatures of steam and molten salt, as well as the change in the heat storage capacity of the molten salt heat storage part, can be output within a certain heat storage time.

[0122] This method can reflect the influence of the heat storage time and the heat exchanger size on the peak shaving process and peak shaving capacity, which are reflected in Figure 4 as follows.

[0123] In this method, the peak shaving process of the output power of the thermal power unit is realized by implementing PID control on the extraction steam flow rate, that is, taking the output power of 35% THA as the target value and the extraction steam flow rate as the adjustment quantity, and finally completing the dynamic modeling of changing the extraction steam flow rate to realize the peak shaving of the unit.

[0124] In addition, if the method of the present invention is used to realize the load increase and peak shaving process of the unit, the following process can be referred to: Water is extracted through two pumping valves and enters the molten salt-steam heat exchanger 5 to be heated to superheated steam, and then returns to the thermal power unit through the steam return point 1 18-1 and the steam return point 2 18-2 from the intermediate-pressure steam turbine unit 8 and the low-pressure steam turbine unit 9 respectively. This part of the superheated steam will drive the steam turbine to do additional work to rapidly increase the output power of the thermal power unit.

[0125] As Figure 3 shown, by comparing the designed output power of a 350MW thermal power unit under five operating conditions of 30%, 40%, 50%, 75%, and 100% THA with the simulated output power values of the thermal power unit built by the above method, it can be found that the maximum difference does not exceed 0.8%. It can be concluded that the method of the present invention has high accuracy when applied to the prediction scenario of the output power of thermal power units.

[0126] From Figure 4 it can be seen that the present invention can excellently simulate the power change process of the thermal power unit during peak shaving after coupling the molten salt heat storage part. It can be observed that for the two operating conditions of extracting steam into the low-pressure steam turbine unit 9 and extracting steam into the condenser 10, the output power of the thermal power unit will show two peak shaving curves due to different steam return points. In summary, the present invention accurately simulates the influence of extraction steam on the peak shaving power change process of the thermal power unit.

[0127] The method of the present invention uses two conventional software for modeling, considers the influence of the simulated extraction steam process on the output parameters of the steam turbine, significantly improves the accuracy of predicting the real-time output power of the steam turbine, and effectively solves the problem of inaccurate calculation of the output power of the steam turbine in the prior art. In addition, the present invention can re-incorporate the steam returned from the molten salt heat storage part into the iterative cycle of the thermal power unit for calculation, realizes the efficient coupling of the thermal power unit and the molten salt heat storage part, and optimizes the peak shaving performance of the thermal power unit. This method not only reduces the dependence on measured data, simplifies the process of determining model parameters, but also reduces the frequency of model updates and the development and maintenance costs of the system. Therefore, the present invention has obvious advantages in improving simulation accuracy, reducing simulation difficulty and enhancing economic benefits, and provides more reliable and more economical technical support for the operation management and optimization of thermal power units.

[0128] Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not used to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, for those skilled in the art, they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims

1. A simulation method for realizing dynamic peak shaving simulation of thermal power units, characterized in that It includes the following steps: S1: Build a simulation model of a thermal power unit in a process simulation software; the thermal power unit includes: a boiler, a steam turbine unit, a condenser, a high-pressure heater, and a low-pressure heater; the high-temperature and high-pressure steam output by the boiler is extracted and input into the steam turbine unit to drive the steam turbine to do work; the low-temperature and low-pressure steam discharged from the steam turbine unit is input into the condenser to become condensate, and the condensate is heated by the low-pressure heater and the high-pressure heater in sequence and then returned to the boiler, and the low-pressure heater and the high-pressure heater use the steam extraction of the steam turbine for heating; S2: Input the basic parameters of the thermal power unit in the steady state into the process simulation software and use them as the peak shaving base value; S3: The programming software reads the root files of each unit component of the thermal power unit in the process simulation software; S4: Build and train a prediction model for the output parameters after the steam turbine stage in the programming software, and the output parameters include the outlet pressure and the outlet temperature; after the training is completed, based on the input data of each stage of the steam turbine of the thermal power unit after steam extraction, predict the outlet pressure and the outlet temperature of the corresponding steam turbine; S5: The programming software returns the outlet pressure and the outlet temperature of each stage of the steam turbine to the process simulation software to obtain the output power of the corresponding steam turbine; combined with the terminal difference of the high-pressure heater or the terminal difference of the low-pressure heater in the basic parameters, calculate the internal steam extraction amount of the thermal power unit required for this steam turbine, so as to obtain the steam flow rate input into the inlet of the next stage of the steam turbine; according to the output power of each stage of the steam turbine, obtain the output power of the thermal power unit; S6: Continuously change the external steam extraction amount of the thermal power unit, and then change the input data of each stage of the steam turbine of the thermal power unit after steam extraction until the output power of the thermal power unit reaches the target peak shaving value.

2. The simulation method for realizing dynamic peak shaving simulation of thermal power units according to claim 1, characterized in that, The thermal power unit is also coupled with a molten salt energy storage system, and the molten salt energy storage system includes: a hot salt tank, a cold salt tank, a steam-molten salt heat exchanger, a molten salt-steam heat exchanger, and a molten salt pump; the input steam inlet of the steam-molten salt heat exchanger is the high-temperature and high-pressure steam extracted from the output of the boiler, the molten salt inlet is connected to the cold salt tank through the molten salt pump, the molten salt outlet is connected to the hot salt tank, and the steam outlet outputs the heat-exchanged steam and returns it to the thermal power unit; the water inlet of the molten salt-steam heat exchanger inputs part of the condensate, the molten salt inlet is connected to the hot salt tank through the molten salt pump, the molten salt outlet is connected to the cold salt tank, and the steam outlet outputs the heat-exchanged steam and returns it to the thermal power unit; the connections of the steam-molten salt heat exchanger and the molten salt-steam heat exchanger to the thermal power unit are controlled by valves to be opened and closed; S1 also includes building a simulation model of the steam-molten salt heat exchanger and a model of the molten salt-steam heat exchanger in the programming software to obtain the temperature changes of the molten salt and the steam in the two heat exchangers during the heat exchange process; during the execution of S6, return the parameter information of the two heat exchangers under different peak shaving requirements to the process simulation software, and the parameter information includes temperature parameters, steam flow rate, and outlet pressure.

3. The simulation method for realizing the dynamic peak shaving simulation of a thermal power unit according to claim 1, wherein The process simulation software selects Aspen Plus, and the programming software selects MATLAB. The data interface between Aspen Plus and MATLAB is built using Active X technology to achieve data transmission.

4. The simulation method for realizing the dynamic peak shaving simulation of a thermal power unit according to claim 3, wherein S1 is realized through the following sub-steps: (1) Selection of physical property methods: Input the components appearing in all input streams, including: fuel, air, water or steam; select the PENG-ROB local physical property method for the components of fuel and air, and select the STEAM-TA global physical property method for the components involving water or steam; (2) Select the corresponding unit components in Aspen Plus, and build its simulation model according to the heat balance diagram of the thermal power unit under the basic operating conditions.

5. The simulation method for realizing dynamic peak shaving simulation of thermal power units according to claim 1, characterized in that, In S2, the basic parameters include: the parameters of the high-temperature and high-pressure steam output by the boiler, the extraction steam pressures of each stage group of the steam turbine, the terminal differences of the high-pressure heaters, the terminal differences of the low-pressure heaters, the fuel input, and the make-up water; the parameters of the high-temperature and high-pressure steam output by the boiler include the outlet flow rate, pressure, and temperature; the basic parameters are obtained according to the heat balance diagram of the thermal power unit under the basic operating conditions.

6. The simulation method for realizing dynamic peak shaving simulation of thermal power units according to claim 1, characterized in that In S4, the prediction model for the output parameters after the steam turbine stage uses a support vector regression model. The historical operation data of each stage of the steam turbine of the thermal power unit under various operating conditions are standardized and used as the training data set. The historical operation data include: the flow rate, inlet pressure and temperature, and outlet pressure and temperature of a single-stage steam turbine; use the training data set to train the support vector regression model to realize the prediction of the outlet pressure and outlet temperature.

7. The simulation method for realizing dynamic peak shaving simulation of thermal power units according to claim 2, characterized in that, During the modeling process of the steam-salt heat exchanger simulation model and the salt-steam heat exchanger model, the following assumptions are made: (1) Assume that there is no heat transfer loss in the heat exchanger; (2) Assume that there is no temperature cross during the heat transfer process; (3) Assume that the flow states of steam and molten salt are uniform, and all parameters are consistent in space, that is, consistent on the cross-section of the pipeline.

8. The simulation method for realizing the dynamic peak shaving simulation of a thermal power unit according to claim 7, characterized in that, When building the steam-salt heat exchanger simulation model, first calculate the steam flow velocity using the steam flow rate and the molten salt flow rate. The expression is as follows: where, V steam represents the flow velocity of steam, m steam represents the mass flow rate of steam, ρ steam represents the density of steam, obtained by calling the Refprop material database, A steam represents the cross-sectional area of the pipeline; D represents the inner diameter of the pipeline; Reynolds number Re of steam flow steam , Prandtl number Pr steam and Nusselt number Nu steam Calculate the heat transfer coefficient U, and the expression is as follows: where μ steam is the dynamic viscosity of the steam, c steam is the specific heat capacity of the steam, k steam is the thermal conductivity of the steam, and all three are obtained by calling the Refprop material database; Discretize the space of the heat exchanger, and calculate the heat release Q of the steam in each small section of the single pipe and the heat absorption Q1 of the molten salt in the corresponding small section of the single pipe during the heat transfer process. The expressions are as follows: Q = U·D·π·dz·ΔT Q1 = -n1·Q ΔT=T steam -T salt In the formula, dz is the space discretization step size, ΔT is the heat transfer temperature difference between steam and molten salt, and n1 is the number of small sections of single pipes in a single heat exchanger; Perform time discretization and calculate the steam temperature T steam and the molten salt temperature T salt at different times during the heat exchange process. The temperature change expression is as follows: where m salt is the mass flow rate of the molten salt, and c salt is the specific heat capacity of the molten salt; Integrate the heat storage capacity of the molten salt to obtain the total heat storage capacity Q of the molten salt flowing through the steam-molten salt heat exchanger at the corresponding time salt-ex , to show the total heat that the molten salt can store after extracting a specified amount of steam during the peak shaving process. The expression is as follows: In the formula, n2 is the number of steam-salt heat exchangers; If the molten salt after heat exchange needs to be heated to a certain specified temperature, the molten salt is heated by an electric heater, and finally the total heat storage Q of the molten salt entering the hot salt tank is obtained salt , and the expression is as follows: Q E = m salt · c salt · [T salt-set - T salt (end)] Q salt = Q salt-ex + Q E Where, T salt-set represents the molten salt temperature after the heat exchange ends, and T salt (end) represents the specified molten salt temperature; When building the salt-steam heat exchanger simulation model, consider the phase change during the process from condensate to steam, and calculate the change in steam temperature using the enthalpy value. The expression for the change in the outlet enthalpy value of the steam-salt heat exchanger at different times during the heat transfer process is as follows: where m water is the flow rate of the water at the water inlet of the steam-salt heat exchanger, h i+1 represents the outlet enthalpy value of the steam-salt heat exchanger during the (i + 1)-th iteration calculation, h i represents the outlet enthalpy value of the steam-salt heat exchanger during the i-th iteration calculation. According to the outlet enthalpy value and pressure of the salt-steam heat exchanger, call the Refprop material database to obtain the steam temperature at the steam outlet end of the salt-steam heat exchanger.

9. A simulation system for realizing the dynamic peak shaving simulation of a thermal power unit, which is used to realize the simulation method for realizing the dynamic peak shaving simulation of a thermal power unit according to any one of claims 1-8, characterized in that, Including: Process simulation software, and programming software that can be connected for data transmission; The process simulation software is used to build the simulation model of the thermal power unit. The programming software reads and writes the operating parameters of the thermal power unit across platforms through data transmission connection, and predicts the output parameters of each stage of the steam turbine of the thermal power unit based on the read operating parameters, so as to complete the real-time scheduling and control of the simulation model of the thermal power unit and realize the dynamic peak shaving simulation.

10. The simulation system for realizing dynamic peak shaving simulation of thermal power units according to claim 9, characterized in that The programming software is also used to construct models of a steam-salt heat exchanger and a salt-steam heat exchanger. The steam-salt heat exchanger is used to simulate the heat exchange process of "heating molten salt with steam extracted from a thermal power unit", and the salt-steam heat exchanger is used to simulate the heat exchange process of "heating condensate water extracted from a thermal power unit with molten salt", so as to jointly realize the peak shaving simulation of the molten salt energy storage system coupled with the thermal power unit.

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