A circulating power generation system using sand heat storage

Abstract

The present invention discloses a circulating power generation system using sand to store heat, which belongs to the field of new energy storage and efficient power generation technology. It includes: an electric heating module for inputting photovoltaic electric heating thermal oil as high-temperature thermal oil; a sand heat storage module for storing the thermal energy of the thermal oil, and delivering the cooled low-temperature thermal oil to the electric heating module, and delivering the high-temperature heat to the supercritical CO2 power generation module; the supercritical CO2 power generation module for obtaining high-temperature heat from the sand heat storage module, implementing a working fluid cycle, and delivering the low-temperature thermal oil to the sand heat storage module; an intelligent control module for monitoring the working fluid cycle process and controlling the working fluid to maintain a supercritical state. The present invention utilizes the sand heat storage module to store the heat energy generated by the electric heating module, and delivers the heat energy to the supercritical CO2 power generation module when needed, thereby achieving efficient energy storage and utilization, achieving improved economic efficiency, and solving the problem of poor economic efficiency caused by the high cost of heat storage media in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy storage and high-efficiency power generation, and in particular to a circulating power generation system utilizing sand to store heat. Background Art

[0002] As the global energy mix accelerates its shift toward renewable energy, the intermittent nature of photovoltaic and wind power generation creates an urgent need for long-cycle, highly stable energy storage technologies. Against this backdrop, molten salt thermal storage coupled with steam power generation, a mainstream technology for concentrated solar thermal power plants, achieves spatial and temporal transfer of electrical energy through thermal energy, and has become a key infrastructure supporting grid peak regulation and clean energy consumption.

[0003] The existing molten salt heat storage system converts surplus electricity into thermal energy storage in high-temperature molten salt through an electric heating device, and then drives a traditional steam Rankine cycle unit to convert heat into work, ultimately achieving stable power output.

[0004] However, due to the high procurement cost of molten salt media and the risk of low-temperature solidification, the operating temperature range of the heat storage system is narrow and the volume energy density is low; the steam power generation link has low cycle efficiency, the supporting equipment occupies a large area and the power response is delayed; at the same time, the dynamic coordination ability between the three major subsystems of electric heating, heat storage tank and steam turbine is weak, the overall load regulation margin of the system is insufficient and the heat exchange temperature difference in the energy release process is significant. The core contradictions are concentrated in poor economy, limited efficiency and insufficient operational flexibility. Summary of the Invention

[0005] The embodiments of the present application provide a circulating power generation system that utilizes sand to store heat, thereby solving the problem of poor economic efficiency in the prior art due to the high cost of heat storage media and achieving improved economic efficiency.

[0006] The embodiment of the present application provides a cyclic power generation system using sand heat storage, comprising: an electric heating module, a sand heat storage module, a supercritical CO2 power generation module, and an intelligent control module;

[0007] The electric heating module is used to input high-temperature thermal oil for photovoltaic electric heating and transport the high-temperature thermal oil to the sand heat storage module, and is also used to receive low-temperature thermal oil transported from the sand heat storage module;

[0008] The sand heat storage module is used to store the thermal energy of the thermal oil and deliver the cooled low-temperature thermal oil to the electric heating module, and also to deliver the high-temperature heat to the supercritical CO2 power generation module;

[0009] The supercritical CO2 power generation module is used to obtain high-temperature heat from the sand heat storage module, implement working medium circulation, and transport low-temperature heat transfer oil to the sand heat storage module;

[0010] The intelligent control module is used to monitor the working medium circulation process, dynamically adjust the compressor speed and valve opening through PLC, and control the working medium to maintain a supercritical state;

[0011] Specifically, the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature are obtained and preprocessed, and a critical deviation value is calculated based on the preprocessed data;

[0012] Then, the speed correction amount and valve opening correction amount are obtained according to the critical deviation value to adjust the compressor speed and valve opening;

[0013] The critical deviation value is obtained as follows:

[0014] The critical deviation value is calculated by the formula using the pre-processed turbine inlet pressure, turbine inlet temperature, CO2 density, and corresponding critical parameters and weight coefficients;

[0015] The calculation formula of critical deviation value is:

[0016] ;

[0017] in, is the critical deviation value, 、 、 are the weight coefficients of pressure, temperature and density respectively, is the filtered turbine inlet pressure, is the critical pressure of CO2, is the filtered turbine inlet temperature, is the critical temperature of CO2, is the CO2 density, is the critical density of CO2.

[0018] Furthermore, the electric heating module includes: an electric input unit, an electric heater, a first heat transfer oil input unit and a first heat transfer oil output unit:

[0019] The electric input unit is used to connect to photovoltaic direct current to obtain electric energy;

[0020] The electric heater is used to convert input electrical energy into thermal energy to heat the thermal oil;

[0021] The first heat transfer oil input unit is used to receive the low-temperature heat transfer oil delivered by the sand heat storage module;

[0022] The first heat transfer oil output unit is used to deliver the heated high-temperature heat transfer oil to the sand heat storage module.

[0023] Furthermore, the sand heat storage module includes a sand heat storage tank, a second heat transfer oil input unit, and a second heat transfer oil output unit:

[0024] The sand heat storage tank is used to store the thermal energy of the thermal oil, store and release heat through the sand medium inside, and is also used to monitor the temperature distribution of the sand in real time;

[0025] The second heat transfer oil input unit is used to receive the high-temperature heat transfer oil delivered by the electric heating module, and is also used to receive the low-temperature heat transfer oil delivered by the supercritical CO2 power generation module;

[0026] The second heat transfer oil output unit is used to deliver high-temperature heat to the supercritical CO2 power generation module, and is also used to deliver low-temperature heat transfer oil to the electric heating module.

[0027] Furthermore, the supercritical CO2 power generation module includes a CO2 heater, a turbine, an electric motor, a compressor, a cooler, and a regenerator:

[0028] The CO2 heater is used to further heat the high-temperature and high-pressure CO2 working medium output from the regenerator to a supercritical state using the high-temperature heat, and then transmit it to the turbine;

[0029] The turbine is used to receive the supercritical CO2 working medium from the CO2 heater and convert its expansion work into mechanical energy to drive the generator to generate electricity, while at the same time transporting the low-temperature and low-pressure CO2 working medium after work to the regenerator;

[0030] The electric motor is used to convert the mechanical energy output by the turbine into electrical energy and transmit it to the outside. It is also used to provide electrical energy to drive the compressor during the system startup phase or when the compressor requires additional power.

[0031] The compressor is used to receive the low-temperature and low-pressure CO2 working medium from the cooler, compress it into high-temperature and high-pressure CO2 working medium, and then transport it to the regenerator;

[0032] The cooler is used to receive the high-temperature and high-pressure CO2 working medium from the regenerator, cool it to low-temperature and high-pressure CO2 working medium, and deliver it to the compressor;

[0033] The regenerator is used to receive low-temperature, low-pressure CO2 working fluid from the turbine and high-temperature, high-pressure CO2 working fluid from the compressor, recover the residual heat of the low-temperature, low-pressure CO2 working fluid through heat exchange to preheat the low-temperature, high-pressure CO2 working fluid, and then transport the preheated high-temperature, high-pressure CO2 working fluid to the turbine, and at the same time transport the further cooled low-temperature, low-pressure CO2 working fluid to the cooler.

[0034] Furthermore, the intelligent control module includes: a data monitoring and processing module, a deviation statistics module, a valve opening correction analysis module, and a speed correction analysis module;

[0035] The data monitoring and processing module is used to obtain the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature, perform preprocessing, and transmit the preprocessed data to the deviation statistics module;

[0036] The deviation statistics module is used to receive the pre-processed data, calculate and obtain the critical deviation value, and transmit the critical deviation value to the valve opening correction analysis module and the speed correction analysis module;

[0037] The valve opening correction value analysis module is used to receive the critical deviation value to calculate the valve opening correction value, and transmit the valve opening correction value to the electric heating module and the supercritical CO2 power generation module;

[0038] The speed correction value analysis module is used to receive the critical deviation value to calculate the speed correction value and transmit the speed correction value to the supercritical CO2 power generation module.

[0039] Furthermore, the pre-processing process is:

[0040] Outliers are removed from turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature. If the deviation between the data and the sliding mean is within N times the standard deviation, the original data is retained; otherwise, the sliding mean is used instead.

[0041] Furthermore, the CO2 density is obtained as follows:

[0042] Obtain turbine inlet pressure and turbine inlet temperature data, use the Span-Wagner state equation, and calculate the CO2 density based on the CO2 density acquisition formula;

[0043] The formula for obtaining CO2 density is: ;

[0044] in, is the CO2 density, is the turbine inlet pressure, is the turbine inlet temperature, is the SpanWagner equation of state.

[0045] Furthermore, the valve opening correction amount is obtained in the following manner:

[0046] The valve opening correction amount is calculated by formula using the critical deviation value, turbine inlet pressure, CO2 critical pressure and valve opening control parameters;

[0047] The calculation formula for the valve opening correction is: ;

[0048] in, is the valve opening correction value, is the proportional gain.

[0049] Furthermore, the speed correction amount is obtained as follows:

[0050] The speed correction amount is calculated by the formula using the reference mass flow, actual CO2 mass flow, rated speed and speed control parameters;

[0051] The calculation formula of the speed correction is: ;

[0052] in, is the speed correction value, is the rated speed, is the speed control gain, is the reference mass flow rate, is the actual CO2 mass flow rate.

[0053] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0054] 1. By using the sand heat storage module to store the heat energy generated by the electric heating module and transferring the heat energy to the supercritical CO2 power generation module when needed, efficient energy storage and utilization are achieved, thereby realizing a technology that improves economic efficiency and effectively solves the problem of poor economy caused by the high cost of heat storage media in the existing technology.

[0055] 2. The supercritical CO2 power generation module realizes efficient conversion of thermal energy into electrical energy, thereby improving the heat-to-work conversion efficiency and further improving the conversion efficiency.

[0056] 3. The intelligent control module monitors the working fluid circulation process in real time and dynamically adjusts the compressor speed and valve opening to control the working fluid to maintain a supercritical state, thereby achieving rapid system response and load regulation, thereby improving operational flexibility.

[0057] 4. By monitoring the working fluid circulation process through the intelligent control module, dynamically adjusting the compressor speed and valve opening through PLC, controlling the working fluid to maintain a supercritical state, and accurately regulating the valve opening and compressor speed, the working fluid is ensured to circulate stably in the supercritical state, thereby achieving improvements in power generation efficiency and system response speed, and enhancing overall performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of sand heat storage coupled with supercritical CO2 cycle power generation and energy storage. DETAILED DESCRIPTION

[0059] The embodiment of the present application solves the problem of poor economy in the prior art caused by the high cost of heat storage media by providing a circulating power generation system that uses sand to store heat. By using the sand heat storage module to store the heat energy generated by the electric heating module and transmitting the heat energy to the supercritical CO2 power generation module when needed, efficient energy storage and utilization are achieved, thereby realizing improved economy.

[0060] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0061] like Figure 1 As shown, the embodiment of the present application provides a cyclic power generation system using sand heat storage, including: an electric heating module, a sand heat storage module, a supercritical CO2 power generation module, and an intelligent control module;

[0062] The electric heating module is used to input high-temperature thermal oil for photovoltaic electric heating and transport the high-temperature thermal oil to the sand heat storage module, and is also used to receive low-temperature thermal oil transported from the sand heat storage module;

[0063] The sand heat storage module is used to store the thermal energy of the thermal oil and deliver the cooled low-temperature thermal oil to the electric heating module, and also to deliver the high-temperature heat to the supercritical CO2 power generation module;

[0064] The supercritical CO2 power generation module is used to obtain high-temperature heat from the sand heat storage module, implement working medium circulation, and transport low-temperature heat transfer oil to the sand heat storage module;

[0065] The intelligent control module is used to monitor the working medium circulation process, dynamically adjust the compressor speed and valve opening through PLC, and control the working medium to maintain a supercritical state;

[0066] Specifically, the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature are obtained and preprocessed, and a critical deviation value is calculated based on the preprocessed data;

[0067] Then, the speed correction amount and valve opening correction amount are obtained according to the critical deviation value to adjust the compressor speed and valve opening;

[0068] The critical deviation value is obtained as follows:

[0069] The critical deviation value is calculated by the formula using the pre-processed turbine inlet pressure, turbine inlet temperature, CO2 density, and corresponding critical parameters and weight coefficients;

[0070] The calculation formula of critical deviation value is:

[0071] ;

[0072] in, is the critical deviation value, 、 、 are the weight coefficients of pressure, temperature and density respectively, is the filtered turbine inlet pressure, is the critical pressure of CO2, is the filtered turbine inlet temperature, is the critical temperature of CO2, is the CO2 density, is the critical density of CO2.

[0073] In this embodiment, photovoltaic power is converted into thermal energy through an electric heating module and stored in a sand heat storage module. A supercritical CO2 power generation module is used to achieve efficient conversion of thermal energy into electrical energy. An intelligent control module ensures a stable and reliable power generation process. Low temperature refers to 100~150℃, high temperature refers to 400~600℃, less than 0.5MPa is low pressure, and greater than 20MPa is high pressure.

[0074] The sand heat storage module has the advantages of high heat storage density and low cost, and can effectively store the heat energy generated by the electric heating module; the supercritical CO2 power generation module is highly efficient, compact, and fast-responding, and can quickly respond to the peak-shaving needs of the power grid; the intelligent control module ensures the stable operation of the system and efficient energy conversion, improving the overall power generation efficiency.

[0075] Furthermore, the electric heating module includes: an electric input unit, an electric heater, a first heat transfer oil input unit and a first heat transfer oil output unit:

[0076] The electric input unit is used to connect to photovoltaic direct current to obtain electric energy;

[0077] The electric heater is used to convert input electrical energy into thermal energy to heat the thermal oil;

[0078] The first heat transfer oil input unit is used to receive the low-temperature heat transfer oil delivered by the sand heat storage module;

[0079] The first heat transfer oil output unit is used to deliver the heated high-temperature heat transfer oil to the sand heat storage module.

[0080] In this embodiment, the electric heating module efficiently transfers heat energy through thermal oil, connecting photovoltaic power to the sand heat storage module. The electric heater directly heats the thermal oil, enabling rapid conversion of photovoltaic power into thermal energy, providing a stable heat source for the sand heat storage module. The thermal oil delivery unit ensures efficient heat transfer, minimizing energy loss.

[0081] Furthermore, the sand heat storage module includes a sand heat storage tank, a second heat transfer oil input unit, and a second heat transfer oil output unit:

[0082] The sand heat storage tank is used to store the thermal energy of the thermal oil, store and release heat through the sand medium inside, and is also used to monitor the temperature distribution of the sand in real time;

[0083] The second heat transfer oil input unit is used to receive the high-temperature heat transfer oil delivered by the electric heating module, and is also used to receive the low-temperature heat transfer oil delivered by the supercritical CO2 power generation module;

[0084] The second heat transfer oil output unit is used to deliver high-temperature heat to the supercritical CO2 power generation module, and is also used to deliver low-temperature heat transfer oil to the electric heating module.

[0085] In this embodiment, the sand thermal storage module utilizes sand thermal storage tanks to efficiently store heat, ensuring even heat distribution and long-term heat preservation. Sand, as a low-cost heat storage medium with high heat density, can effectively store large amounts of heat. Combined with temperature monitoring devices and insulation, this ensures a stable supply of heat to the power generation module, improving the system's heat storage and release efficiency and reducing operating costs.

[0086] Furthermore, the supercritical CO2 power generation module includes a CO2 heater, a turbine, an electric motor, a compressor, a cooler, and a regenerator:

[0087] The CO2 heater is used to further heat the high-temperature and high-pressure CO2 working medium output from the regenerator to a supercritical state using the high-temperature heat, and then transmit it to the turbine;

[0088] The turbine is used to receive the supercritical CO2 working medium from the CO2 heater and convert its expansion work into mechanical energy to drive the generator to generate electricity, while at the same time transporting the low-temperature and low-pressure CO2 working medium after work to the regenerator;

[0089] The electric motor is used to convert the mechanical energy output by the turbine into electrical energy and transmit it to the outside. It is also used to provide electrical energy to drive the compressor during the system startup phase or when the compressor requires additional power.

[0090] The compressor is used to receive the low-temperature and low-pressure CO2 working medium from the cooler, compress it into high-temperature and high-pressure CO2 working medium, and then transport it to the regenerator;

[0091] The cooler is used to receive the high-temperature and high-pressure CO2 working medium from the regenerator, cool it to low-temperature and high-pressure CO2 working medium, and deliver it to the compressor;

[0092] The regenerator is used to receive low-temperature, low-pressure CO2 working fluid from the turbine and high-temperature, high-pressure CO2 working fluid from the compressor, recover the residual heat of the low-temperature, low-pressure CO2 working fluid through heat exchange to preheat the low-temperature, high-pressure CO2 working fluid, and then transport the preheated high-temperature, high-pressure CO2 working fluid to the turbine, and at the same time transport the further cooled low-temperature, low-pressure CO2 working fluid to the cooler.

[0093] In this embodiment, the supercritical CO2 power generation module achieves efficient conversion of thermal energy into electrical energy through the coordinated operation of a CO2 heater, turbine, motor, compressor, regenerator, and cooler. The unique properties of supercritical CO2 allow it to accommodate more heat in a smaller volume, improving heat-to-work conversion efficiency and reducing equipment size and footprint. The regenerator recycles and reuses heat, further improving power generation efficiency. The cooler ensures stable CO2 circulation. The tight coordination of these components ensures efficient and stable operation of the power generation module, enabling rapid response to grid peak-shaving demands.

[0094] Furthermore, the intelligent control module includes: a data monitoring and processing module, a deviation statistics module, a valve opening correction analysis module, and a speed correction analysis module;

[0095] The data monitoring and processing module is used to obtain the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature, perform preprocessing, and transmit the preprocessed data to the deviation statistics module;

[0096] The deviation statistics module is used to receive the pre-processed data, calculate and obtain the critical deviation value, and transmit the critical deviation value to the valve opening correction analysis module and the speed correction analysis module;

[0097] The valve opening correction value analysis module is used to receive the critical deviation value to calculate the valve opening correction value, and transmit the valve opening correction value to the electric heating module and the supercritical CO2 power generation module;

[0098] The speed correction value analysis module is used to receive the critical deviation value to calculate the speed correction value and transmit the speed correction value to the supercritical CO2 power generation module.

[0099] In this embodiment, the intelligent control module precisely regulates valve opening and compressor speed by real-time monitoring and analysis of key operating parameters. This ensures stable circulation of the working fluid in the supercritical state, improving power generation efficiency and system response speed, ensuring stable system operation and efficient energy conversion, and enhancing overall performance and reliability.

[0100] Furthermore, the pre-processing process is:

[0101] Outliers are removed from turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature. If the deviation between the data and the sliding mean is within N times the standard deviation, the original data is retained; otherwise, the sliding mean is used instead.

[0102] In this embodiment, the preprocessing process ensures the accuracy and reliability of the data and improves the precision of subsequent calculations.

[0103] In this embodiment, the Span-Wagner state equation is used to calculate the CO2 density, which accurately describes the density change of CO2 at different pressures and temperatures, thereby improving power generation efficiency and system performance.

[0104] Furthermore, the CO2 density is obtained as follows:

[0105] Obtain turbine inlet pressure and turbine inlet temperature data, use the Span-Wagner state equation, and calculate the CO2 density based on the CO2 density acquisition formula;

[0106] The formula for obtaining CO2 density is: ;

[0107] in, is the CO2 density, is the turbine inlet pressure, is the turbine inlet temperature, is the SpanWagner equation of state.

[0108] In this embodiment, by calculating the critical deviation value, the system can monitor the critical state of the working fluid in real time, ensure its stable operation in the supercritical region, and prevent the working fluid from undergoing phase change when approaching the critical point, thereby avoiding system performance degradation or damage, and ensuring stable operation and efficient power generation of the system.

[0109] Furthermore, the valve opening correction amount is obtained in the following manner:

[0110] The valve opening correction amount is calculated by formula using the critical deviation value, turbine inlet pressure, CO2 critical pressure and valve opening control parameters;

[0111] The calculation formula for the valve opening correction is: ;

[0112] in, is the valve opening correction value, is the proportional gain.

[0113] In this embodiment, by calculating the valve opening correction amount, the system can accurately adjust the valve opening to maintain the working fluid in a supercritical state, thereby improving the thermal efficiency and power generation efficiency of the system, reducing energy loss, and improving the response speed and stability of the system.

[0114] Furthermore, the speed correction amount is obtained as follows:

[0115] The speed correction amount is calculated by the formula using the reference mass flow, actual CO2 mass flow, rated speed and speed control parameters;

[0116] The calculation formula of the speed correction is: ;

[0117] in, is the speed correction value, is the rated speed, is the speed control gain, is the reference mass flow rate, is the actual CO2 mass flow rate.

[0118] In this embodiment, by calculating the speed correction amount, the system can accurately control the speed of the compressor to adapt to different working conditions, improve the operating efficiency and stability of the system, reduce energy consumption, and at the same time improve the response speed and adaptability of the system, ensuring efficient and stable operation under different working conditions.

[0119] In summary, the embodiment of the present application uses the sand heat storage module to store the heat energy generated by the electric heating module, and transmits the heat energy to the supercritical CO2 power generation module when needed, thereby achieving efficient energy storage and utilization and improving economic efficiency.

[0120] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CDROM, optical storage, etc.) containing computer-usable program code.

[0121] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0122] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0123] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0124] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0125] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A circulating power generation system utilizing sand heat storage, characterized in that: include: Electric heating module, sand heat storage module, supercritical CO2 power generation module, intelligent control module; The electric heating module is used to input high-temperature thermal oil for photovoltaic electric heating and transport the high-temperature thermal oil to the sand heat storage module, and is also used to receive low-temperature thermal oil transported from the sand heat storage module; The sand heat storage module is used to store the thermal energy of the thermal oil and deliver the cooled low-temperature thermal oil to the electric heating module, and also to deliver the high-temperature heat to the supercritical CO2 power generation module; The supercritical CO2 power generation module is used to obtain high-temperature heat from the sand heat storage module, implement working medium circulation, and transport low-temperature heat transfer oil to the sand heat storage module; The intelligent control module is used to monitor the working medium circulation process, dynamically adjust the compressor speed and valve opening through PLC, and control the working medium to maintain a supercritical state; Specifically, the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature are obtained and preprocessed, and a critical deviation value is calculated based on the preprocessed data; Then, the speed correction amount and valve opening correction amount are obtained according to the critical deviation value to adjust the compressor speed and valve opening; The critical deviation value is obtained as follows: The critical deviation value is calculated by the formula using the pre-processed turbine inlet pressure, turbine inlet temperature, CO2 density, and corresponding critical parameters and weight coefficients; The calculation formula of critical deviation value is: ； in, is the critical deviation value, 、 、 are the weight coefficients of pressure, temperature and density respectively, is the filtered turbine inlet pressure, is the critical pressure of CO2, is the filtered turbine inlet temperature, is the critical temperature of CO2, is the CO2 density, is the critical density of CO2.

2. A cyclic power generation system utilizing sand heat storage as claimed in claim 1, characterized in that: The electric heating module includes: an electric input unit, an electric heater, a first heat transfer oil input unit and a first heat transfer oil output unit: The electric input unit is used to connect to photovoltaic direct current to obtain electric energy; The electric heater is used to convert input electrical energy into thermal energy to heat the thermal oil; The first heat transfer oil input unit is used to receive the low-temperature heat transfer oil delivered by the sand heat storage module; The first heat transfer oil output unit is used to deliver the heated high-temperature heat transfer oil to the sand heat storage module.

3. A cyclic power generation system utilizing sand heat storage as claimed in claim 1, characterized in that: The sand heat storage module includes a sand heat storage tank, a second heat transfer oil input unit, and a second heat transfer oil output unit: The sand heat storage tank is used to store the thermal energy of the thermal oil, store and release heat through the sand medium inside, and is also used to monitor the temperature distribution of the sand in real time; The second heat transfer oil input unit is used to receive the high-temperature heat transfer oil delivered by the electric heating module, and is also used to receive the low-temperature heat transfer oil delivered by the supercritical CO2 power generation module; The second heat transfer oil output unit is used to deliver high-temperature heat to the supercritical CO2 power generation module, and is also used to deliver low-temperature heat transfer oil to the electric heating module.

4. A cyclic power generation system utilizing sand heat storage as claimed in claim 1, characterized in that: The supercritical CO2 power generation module includes a CO2 heater, a turbine, an electric motor, a compressor, a cooler, and a regenerator: The CO2 heater is used to further heat the high-temperature and high-pressure CO2 working medium output from the regenerator to a supercritical state using the high-temperature heat, and then transmit it to the turbine; The turbine is used to receive the supercritical CO2 working medium from the CO2 heater and convert its expansion work into mechanical energy to drive the generator to generate electricity, while at the same time transporting the low-temperature and low-pressure CO2 working medium after work to the regenerator; The electric motor is used to convert the mechanical energy output by the turbine into electrical energy and transmit it to the outside. It is also used to provide electrical energy to drive the compressor during the system startup phase or when the compressor requires additional power. The compressor is used to receive the low-temperature and low-pressure CO2 working medium from the cooler, compress it into high-temperature and high-pressure CO2 working medium, and then transport it to the regenerator; The cooler is used to receive the high-temperature and high-pressure CO2 working medium from the regenerator, cool it to low-temperature and high-pressure CO2 working medium, and deliver it to the compressor; The regenerator is used to receive low-temperature, low-pressure CO2 working fluid from the turbine and high-temperature, high-pressure CO2 working fluid from the compressor, recover the residual heat of the low-temperature, low-pressure CO2 working fluid through heat exchange to preheat the low-temperature, high-pressure CO2 working fluid, and then transport the preheated high-temperature, high-pressure CO2 working fluid to the turbine, and at the same time transport the further cooled low-temperature, low-pressure CO2 working fluid to the cooler.

5. The cyclic power generation system utilizing sand heat storage as claimed in claim 1, characterized in that: The intelligent control module includes: a data monitoring and processing module, a deviation statistics module, a valve opening correction analysis module, and a speed correction analysis module; The data monitoring and processing module is used to obtain the turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature, perform preprocessing, and transmit the preprocessed data to the deviation statistics module; The deviation statistics module is used to receive the pre-processed data, calculate and obtain the critical deviation value, and transmit the critical deviation value to the valve opening correction analysis module and the speed correction analysis module; The valve opening correction value analysis module is used to receive the critical deviation value to calculate the valve opening correction value, and transmit the valve opening correction value to the electric heating module and the supercritical CO2 power generation module; The speed correction value analysis module is used to receive the critical deviation value to calculate the speed correction value and transmit the speed correction value to the supercritical CO2 power generation module.

6. A cyclic power generation system utilizing sand heat storage as claimed in claim 5, characterized in that: The pre-processing process is: Outliers are removed from turbine inlet pressure, turbine inlet temperature, CO2 mass flow rate, and thermal oil inlet temperature. If the deviation between the data and the sliding mean is within N times the standard deviation, the original data is retained; otherwise, the sliding mean is used instead.

7. The cyclic power generation system utilizing sand heat storage as claimed in claim 1, characterized in that: The CO2 density is obtained as follows: Obtain turbine inlet pressure and turbine inlet temperature data, use the Span-Wagner state equation, and calculate the CO2 density based on the CO2 density acquisition formula; The formula for obtaining CO2 density is: ; in, is the CO2 density, is the turbine inlet pressure, is the turbine inlet temperature, is the SpanWagner equation of state.

8. A cyclic power generation system utilizing sand heat storage as claimed in claim 7, characterized in that: The valve opening correction amount is obtained as follows: The valve opening correction amount is calculated by formula using the critical deviation value, turbine inlet pressure, CO2 critical pressure and valve opening control parameters; The calculation formula for the valve opening correction is: ; in, is the valve opening correction value, is the proportional gain.

9. A cyclic power generation system utilizing sand heat storage as claimed in claim 8, characterized in that: The speed correction value is obtained as follows: The speed correction amount is calculated by the formula using the reference mass flow, actual CO2 mass flow, rated speed and speed control parameters; The calculation formula of the speed correction is: ; in, is the speed correction value, is the rated speed, is the speed control gain, is the reference mass flow rate, is the actual CO2 mass flow rate.

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