Cross-season long-time energy storage system and method with sand as heat storage medium

Abstract

The invention discloses a cross-seasonal long-time energy storage system and method with sand as a heat storage medium, and belongs to the technical field of long-time energy storage.The sand is used as the energy storage medium, a photovoltaic system is coupled for energy storage, heat conduction oil heat exchange and steam Rankine cycle are used for energy adjustment and power generation, the activity of heat conduction oil can be kept, and the energy storage efficiency is improved. And meanwhile, the solar energy utilization efficiency is improved. The system cost is reduced, the influence on the environment is reduced, and cross-season long-time energy storage and heat supply of energy storage in summer and heat supply in winter can be achieved.

Description

Technical Field

[0001] The present application relates to a cross-seasonal long-term energy storage system, which belongs to the technical field of long-term energy storage, and in particular to a cross-seasonal long-term energy storage system and method using sand as a heat storage medium. Background Art

[0002] At present, the development of renewable energy is an important part of the global energy strategy. The use of renewable energy such as solar energy has become an important means to cope with the dual challenges of energy security and climate change. my country has very rich solar energy resources, with an annual total solar radiation of 3350-8370MJ / m 2 .

[0003] At present, with the continuous improvement of residents' living standards, the demand for electricity, heat and other energy is increasing. With the improvement of urbanization, the demand for centralized heating is increasing year by year. Traditional fossil energy power generation or heating has a great impact on the environment and is not in line with the current energy utilization strategy and is being gradually eliminated. The current new renewable energy cannot meet the continuous and stable energy supply due to its volatility. Therefore, the cross-seasonal long-term energy storage system can take advantage of the environmental pollution problem in the process of traditional fossil energy utilization, and on the other hand, it can solve the instability problem in the use of renewable energy.

[0004] Current energy storage systems mainly include physical energy storage and chemical energy storage. Physical energy storage has a short storage cycle and large energy loss, making it unsuitable as a long-term energy storage device. Chemical energy storage mainly uses some chemical substances to store electrical energy or thermal energy. These energy storage media are expensive, some will have an impact on the environment, and are not suitable for large-scale energy storage. Summary of the invention

[0005] According to one aspect of the present application, a cross-seasonal long-term energy storage system using sand as a heat storage medium is provided. Using sand as the heat storage medium, a steam Rankine cycle is used for energy regulation in the heat exchange link of the heat transfer oil, which not only avoids the over-temperature failure of the heat transfer oil, but also improves the efficiency of solar energy utilization, realizes cross-seasonal long-term energy storage and heating with energy storage in summer and heating in winter, reduces the heating pressure in the heating season, and supports temperature regulation.

[0006] The cross-seasonal long-term energy storage system using sand as a heat storage medium comprises a heat storage module, which is respectively connected to a photovoltaic power generation module, a steam power generation module and a heating module;

[0007] The photovoltaic power generation module is used to convert light energy into electrical energy to provide energy for the heat storage module;

[0008] The heat storage module is used to convert the electrical energy provided by the photovoltaic power generation module into thermal energy, and use sand as a heat storage medium to perform long-term energy storage across seasons, and use heat transfer oil to perform heat exchange with the steam power generation module and the heating module;

[0009] The steam power generation module is used to perform a steam Rankine cycle when the temperature of the heat transfer oil rises to a threshold percentage of the failure temperature;

[0010] The heating module is used to provide heating to heat users.

[0011] Optionally, the photovoltaic power generation module includes a photovoltaic assembly, a controller and an inverter connected in sequence;

[0012] The photovoltaic module is used to convert light energy into electrical energy;

[0013] The controller is used to regulate the direct current generated by the photovoltaic module and then transmit it to the inverter;

[0014] The inverter is used to convert the regulated direct current into alternating current to supply power to the electric heating device in the heat storage module.

[0015] Optionally, the heat storage module includes: an electric heating submodule, a sand energy storage submodule, and a heat transfer oil circulation submodule connected in sequence; the sand energy storage submodule and the heat transfer oil circulation submodule are respectively connected to a temperature measurement module I and a temperature measurement module II, and the temperature measurement module I is connected to a display alarm module;

[0016] The electric heating submodule is connected to the photovoltaic power generation module and is used to convert electrical energy into thermal energy;

[0017] The sand energy storage submodule contains sand for absorbing the heat provided by the electric heating submodule and raising the temperature;

[0018] The temperature measuring module I and the temperature measuring module II are used to monitor the temperature of the sand and the temperature of the heat transfer oil respectively;

[0019] The display alarm module is used to automatically alarm when the temperature of the sand rises to a threshold percentage of the failure temperature of the thermal oil;

[0020] The heat transfer oil circulation submodule is filled with heat transfer oil, which heats up along with the sand. When the temperature measurement module II detects that the temperature of the heat transfer oil rises to a threshold percentage of its failure temperature, it is used to control the heat transfer oil to circulate in the module, thereby exchanging heat with the steam power generation module and the heating module.

[0021] Optionally, the thermal oil circulation submodule includes a thermal oil heat exchange device, a heat exchanger I, and a heat exchanger II; the thermal oil heat exchange device is used to circulate the thermal oil under the control of the temperature measurement module II, the heat exchanger I is used to exchange heat with the circulating water of the steam power generation module, and the heat exchanger II is used to exchange heat with the circulating water of the heating module.

[0022] Optionally, the electric heating submodule adopts a serpentine design and is laid flat on the bottom of the sand energy storage submodule.

[0023] Optionally, the heat transfer oil heat exchange device comprises a serpentine heat exchange pipe, and the serpentine heat exchange pipe is further bent to form a serpentine heat exchange curved surface;

[0024] Optionally, the thermal oil heat exchange device is arranged in the sand energy storage submodule, and its heat exchange curved surface is arranged perpendicular to the electric heating submodule, and the thermal oil outlet and inlet of the thermal oil heat exchange device are located at the top of the sand energy storage submodule.

[0025] Optionally, the long sides of the heat exchange curved surface correspond to at least one long side of the electric heating submodule.

[0026] Optionally, a three-way valve I is provided on the pipeline between the outlet of the heat transfer oil heat exchange device and the heat exchanger I, which has three inlets and outlets, namely, interface I, interface II and interface III;

[0027] The interface I is connected to the outlet of the heat transfer oil heat exchange device via a heat transfer oil pipeline;

[0028] The interface III is connected to the inlet of the heat transfer oil side part of the heat exchanger I through the heat transfer oil pipeline;

[0029] The interface II is communicated with the inlet of the heat transfer oil side portion of the heat exchanger II via a heat transfer oil pipeline.

[0030] Optionally, a three-way valve II is provided on the pipeline connecting the outlet of the heat exchanger I back to the heat transfer oil heat exchange device, which has three inlets and outlets, namely, an interface IV, an interface V and an interface VI;

[0031] The interface IV is connected to the inlet of the thermal oil heat exchange device via a thermal oil pipeline;

[0032] The interface V is connected to the outlet of the heat transfer oil side portion of the heat exchanger I through the heat transfer oil pipeline;

[0033] The interface VI is connected to the outlet of the heat transfer oil side of the heat exchanger II through a heat transfer pipeline, and is also provided with a control valve III for controlling the flow rate of the heat transfer oil circulation so that the temperature of the heat transfer oil does not exceed the failure temperature.

[0034] Optionally, the steam power generation module comprises: a steam superheater, a steam turbine, and a condenser connected in sequence; the inlet of the steam superheater is connected to the heat exchanger I, and a control valve II is provided on the pipeline between the two; the outlet of the condenser is connected to the heat exchanger I, and a circulating water pump I is provided on the pipeline between the two; the steam turbine is connected to the engine through a coupling;

[0035] When the steam power generation module starts to run, the control valve II opens, and the circulating water pump I starts to run. The circulating water pump I is used to pump circulating water into the heat exchanger I to perform heat exchange with the heat transfer oil of the heat transfer oil circulation submodule. The control valve I controls the flow rate of the heat transfer oil so that the temperature of the heat transfer oil does not exceed the failure temperature, and at the same time, the heat of the heat exchange is kept smaller than the heat exchanged with the sand in the sand energy storage submodule;

[0036] The steam after heat exchange is superheated by the steam superheater and then enters the steam turbine. The steam turbine is used to convert the superheated steam into mechanical energy and transmit it to the engine to generate electrical energy.

[0037] Optionally, the heating module includes: a circulating water pump II and a control valve IV;

[0038] The circulating water pump II is arranged on the pipeline from the heat exchanger II to the heat user;

[0039] The control valve IV is arranged on the pipeline from the heat user back to the heat exchanger II, and is used to control the flow rate of circulating water, so as to realize the temperature regulation of the heat user when heating the system.

[0040] According to another aspect of the present application, a cross-seasonal long-term energy storage method using sand as a heat storage medium is provided, the method comprising two modes: a heat storage and power generation mode, and a heating mode.

[0041] Optionally, in the heat storage and power generation mode, the method comprises:

[0042] Interface I of the three-way valve I is connected to interface III, and interface IV of the three-way valve II is connected to interface V; the photovoltaic module, controller, inverter, electric heating device, temperature measurement module I, and display alarm module start to operate, so that the heat storage medium sand in the sand energy storage submodule starts to heat up;

[0043] Before the temperature measuring module II detects that the temperature of the heat transfer oil has risen to the threshold percentage of the failure temperature, the control valves I, II, III and IV are all in a closed state, and the heat transfer oil circulation pump, circulating water pump I and II stop running. When the temperature of the heat transfer oil rises to the threshold percentage of the failure temperature, the temperature measuring module I controls the display alarm module to sound an alarm, and at the same time, the temperature measuring module II controls the heat transfer oil heat exchange device to start circulating, the control valve I opens, the heat transfer oil circulation pump starts running, and the heat transfer oil enters the heat exchanger I for heat exchange;

[0044] When the steam power generation module starts to run, the control valve II is opened, the circulating water pump I starts to run, and the circulating water enters the heat exchanger I to exchange heat with the heat transfer oil. The flow rate of the heat transfer oil circulation submodule is controlled by the control valve I so that the temperature of the heat transfer oil does not exceed the failure temperature, while keeping the heat exchanged less than the heat exchanged with the sand in the sand energy storage submodule; the steam after heat exchange enters the steam superheater, obtains superheated steam and enters the steam turbine, performs work to generate mechanical energy, and transmits it to the generator to generate electrical energy.

[0045] Optionally, in the heating mode, the method comprises:

[0046] Interface I of the three-way valve I is connected to interface II, and interface IV of the three-way valve II is connected to interface VI. The photovoltaic module, controller, inverter, electric heating device, temperature measurement module I, and display alarm module continue to operate, so that the heat storage medium sand in the sand energy storage submodule continues to absorb heat;

[0047] Close control valve I and control valve II, and the circulating water pump I stops running. Open control valve III and control valve IV, and the thermal oil circulating pump and circulating water pump II start running.

[0048] The heat transfer oil in the heat transfer oil heat exchange device enters the heat exchanger II for heat exchange, and the circulating water of the heating module enters the heat exchanger II for heat exchange with the heat transfer oil, and then is sent to the heat user;

[0049] Heat users adjust control valve IV according to demand and achieve temperature control by changing the flow rate of circulating water.

[0050] The beneficial effects of this application include:

[0051] 1) The cross-seasonal long-term energy storage system using sand as the heat storage medium provided in the present application uses low-cost sand as the heat storage medium, and the sand has a large specific heat capacity and is suitable for large-scale long-term energy storage. By coupling the sand energy storage submodule with the photovoltaic module, the summer solar energy can be converted into thermal energy and stored in the sand for winter heating, realizing cross-seasonal long-term energy storage, effectively reducing the energy supply pressure caused by the surge in energy demand in winter, and there is no impact on the environment during the energy storage and release process.

[0052] 2) The cross-seasonal long-term energy storage system provided in this application using sand as the heat storage medium uses efficient photovoltaic modules and electric heating devices to achieve higher solar energy utilization to meet the heat requirements of the energy storage system.

[0053] 3) The cross-seasonal long-term energy storage system provided in this application uses sand as the heat storage medium, designs a steam power generation module and corresponding pipelines, and uses the steam Rankine cycle to not only effectively avoid the over-temperature failure of the heat transfer oil, but also reasonably distributes energy and improves the efficiency of solar energy utilization.

[0054] 4) This application solves the problem of single energy output of the current renewable energy heating system, realizes multi-energy (electricity, heat) output, improves the utilization rate of solar energy, and realizes the scientific energy use principle of "temperature matching and cascade utilization". BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the heat storage and power generation operating conditions of a cross-seasonal long-term energy storage system using sand as a heat storage medium in one embodiment of the present application;

[0056] Figure 2 This is a schematic diagram of the heating working condition of a cross-seasonal long-term energy storage system using sand as a heat storage medium in one embodiment of the present application;

[0057] Figure 3 A three-dimensional schematic diagram of an electric heating device, a sand heat storage device, and a heat transfer oil heat exchange device of a cross-seasonal long-term energy storage system using sand as a heat storage medium in one embodiment of the present application;

[0058] Figure 4 A schematic top view of an electric heating device, a sand heat storage device, and a thermal oil heat exchange device of a cross-seasonal long-term energy storage system using sand as a heat storage medium in one embodiment of the present application.

[0059] List of parts and reference numerals:

[0060] 1. Photovoltaic module; 2. Controller; 3. Inverter; 4. Electric heating device; 5. Sand energy storage device; 6. Temperature measurement module I; 7. Display alarm module; 8. Thermal oil heat exchange device; 9. Temperature measurement module II; 10. Heat exchanger I; 11. Steam superheater; 12. Steam turbine; 13. Generator; 14. Condenser; 15. Heat exchanger II; 16. Heat user; 17. Thermal oil circulation pump; 18. Control valve I; 19. Control valve II; 20. Circulating water pump I; 21. Control valve III; 22. Control valve IV; 23. Circulating water pump II; 24. Three-way valve I; 25. Three-way valve II. DETAILED DESCRIPTION

[0061] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0062] A cross-seasonal long-term energy storage system using sand as a heat storage medium, comprising a heat storage module, which is respectively connected to a photovoltaic power generation module, a steam power generation module and a heating module;

[0063] The photovoltaic power generation module is used to convert light energy into electrical energy to provide energy for the heat storage module;

[0064] The heat storage module is used to convert the electrical energy provided by the photovoltaic power generation module into thermal energy, and use sand as a heat storage medium to perform long-term energy storage across seasons, and use heat transfer oil to perform heat exchange with the steam power generation module and the heating module;

[0065] The steam power generation module is used to perform a steam Rankine cycle when the temperature of the heat transfer oil rises to a threshold percentage of the failure temperature;

[0066] The heating module is used to provide heating to heat users.

[0067] See also Figure 1 , which shows a cross-seasonal long-term energy storage system using sand as a heat storage medium in an embodiment. The photovoltaic power generation module includes a photovoltaic assembly 1, a controller 2 and an inverter 3 connected in sequence.

[0068] The photovoltaic module 1 is used to convert light energy into electrical energy;

[0069] The controller 2 is used to regulate the direct current generated by the photovoltaic module and then transmit it to the inverter;

[0070] The inverter 3 is used to convert the regulated direct current into alternating current to supply power to the electric heating device 4 in the heat storage module.

[0071] The heat storage module comprises: an electric heating device 4, a sand energy storage device 5, and a heat transfer oil circulation submodule connected in sequence; the sand energy storage submodule and the heat transfer oil circulation submodule are respectively connected to a temperature measurement module I 6 and a temperature measurement module II 9, and the temperature measurement module I is connected to a display alarm module;

[0072] The electric heating device 4 is connected to the inverter 3 and is used to convert electrical energy into thermal energy;

[0073] The sand energy storage device 5 contains sand for absorbing the heat provided by the electric heating device 4 and heating up;

[0074] The temperature measuring module I and the temperature measuring module II are used to monitor the temperature of the sand and the temperature of the heat transfer oil respectively;

[0075] The display alarm module 7 is used to automatically alarm when the temperature of the sand rises to a threshold percentage of the failure temperature of the thermal oil;

[0076] The heat transfer oil circulation submodule is filled with heat transfer oil, which heats up along with the sand. When the temperature measurement module II detects that the temperature of the heat transfer oil rises to a threshold percentage of its failure temperature, it is used to control the heat transfer oil to circulate in the module, thereby exchanging heat with the steam power generation module and the heating module.

[0077] The thermal oil circulation submodule includes a thermal oil heat exchange device 8, a heat exchanger I10, and a heat exchanger II 15; the thermal oil heat exchange device is used to circulate the thermal oil under the control of the temperature measurement module II, the heat exchanger I is used to exchange heat with the circulating water of the steam power generation module, and the heat exchanger II is used to exchange heat with the circulating water of the heating module.

[0078] like Figure 3 , 4 As shown, the electric heating device 4 adopts a serpentine design and is laid flat on the bottom of the sand energy storage device 5 to heat up the heat storage medium sand in the sand energy storage device 5. The heat transfer oil heat exchange device 8 is arranged inside the sand energy storage device 5, and its heat transfer oil outlet and inlet are located at the top of the sand energy storage device 5. The heat transfer oil outlet is connected to the heat exchanger I10, and the heat transfer oil inlet is connected to the heat exchanger II 15.

[0079] A three-dimensional rectangular coordinate system is established with the lower left corner of the sand energy storage device 5 as point O, the long side as the X axis, and the short side as the Y axis. The heat transfer oil heat exchange device 8 adopts a serpentine design on both the XOZ plane and the YOX plane. Specifically, on the XOZ plane, the heat transfer oil heat exchange device 8 adopts a serpentine heat exchange pipe, and heat transfer oil is stored in the pipe; on the YOX plane, the serpentine heat exchange pipe is bent to form a heat exchange surface with a serpentine distribution, and the heat exchange surface is perpendicular to the electric heating device 4, and the long sides of the heat exchange surface correspond to at least one long side of the electric heating device (see Figure 4 ) to absorb as much heat as possible and make the sand heat storage device have a better heat storage effect. When the sand heats up, the heat transfer oil will also heat up.

[0080] A three-way valve I 24 is provided on the pipeline between the outlet of the heat transfer oil heat exchange device and the heat exchanger I, which has three inlets and outlets, namely, interface I, interface II and interface III;

[0081] The interface I is connected to the outlet of the heat transfer oil heat exchange device via a heat transfer oil pipeline;

[0082] The interface III is connected to the inlet of the heat transfer oil side part of the heat exchanger I through the heat transfer oil pipeline;

[0083] The interface II is communicated with the inlet of the heat transfer oil side portion of the heat exchanger II via a heat transfer oil pipeline.

[0084] A three-way valve II 25 is provided on the pipeline connecting the outlet of the heat exchanger I back to the heat transfer oil heat exchange device, which has three inlets and outlets, namely, an interface IV, an interface V and an interface VI;

[0085] The interface IV is connected to the inlet of the thermal oil heat exchange device via a thermal oil pipeline;

[0086] The interface V is connected to the outlet of the heat transfer oil side portion of the heat exchanger I through the heat transfer oil pipeline;

[0087] The interface VI is connected to the outlet of the heat transfer oil side of the heat exchanger II through a heat transfer pipeline, and is also provided with a control valve III for controlling the flow rate of the heat transfer oil circulation so that the temperature of the heat transfer oil does not exceed the failure temperature.

[0088] By adjusting the three-way valve I 24 and the three-way valve II 25, the system can be placed in two working modes: heat storage and power generation and heat supply.

[0089] The present application also provides a cross-seasonal long-term energy storage method using sand as a heat storage medium, including two modes: a heat storage and power generation mode and a heating mode.

[0090] like Figure 1As shown, in the heat storage and power generation mode, the interface I of the three-way valve I is connected to the interface III, the interface IV of the three-way valve II is connected to the interface V, the photovoltaic module 1, the controller 2, the inverter 3, the electric heating device 4, the temperature measurement module I6, and the display alarm module 7 start to operate, and the heat storage medium sand in the sand energy storage device 5 starts to heat up. Before the temperature of the thermal oil rises to 90% of the failure temperature, the control valve I18, the control valve II19, the control valve III21, and the control valve IV22 are in a closed state, the thermal oil circulation pump 17, the circulating water pump I20, and the circulating water pump II23 stop running, and the thermal oil in the thermal oil circulation device 8 is heated up together with the sand. When the temperature of the thermal oil rises to 90% of the failure temperature, the temperature measurement module 6 controls the display alarm module 7 to start an alarm, and at the same time, the temperature measurement module II9 controls the thermal oil heat exchange device to start circulating, the control valve I18 is opened, the thermal oil circulation pump 17 starts to operate, and the thermal oil enters the heat exchanger I10 for heat exchange. The steam power generation system starts to operate, the control valve 19 opens, the circulating water pump 20 starts to operate, the circulating water enters the heat exchanger I to exchange heat with the heat transfer oil, and the steam after heat exchange enters the steam superheater 11. The superheated steam enters the steam turbine 12 to perform work and is converted into mechanical energy. The steam turbine 12 is connected to the generator 13 through a coupling, and the mechanical energy generated by the steam in the steam turbine 13 is transferred to the generator 13 to generate electrical energy. In this mode, the flow rate of the heat transfer oil circulation device is controlled by the control valve 18 so that the temperature of the heat transfer oil does not exceed the failure temperature. At the same time, the heat exchanged with the circulating water of the steam power generation system in the heat exchanger I 10 is less than the heat exchanged with the sand in the sand energy storage device 5. The heat storage medium sand in the sand energy storage device 5 continues to absorb the heat of the electric heating device and continues to heat up to the system set temperature.

[0091] See also Figure 2 In the heating mode, the interface I of the three-way valve I is connected to the interface II, the interface IV of the three-way valve II is connected to the interface VI, the photovoltaic module 1, the controller 2, the inverter 3, the electric heating device 4, the temperature measurement module I6, and the display alarm module 7 continue to operate, and the heat storage medium sand in the sand energy storage device 5 continues to absorb heat. The control valve I18 and the control valve II19 are in the closed state, the circulating water pump I20 stops running, the control valve III21 and the control valve IV22 are opened, and the thermal oil circulating pump 17 and the circulating water pump II23 start running. The thermal oil in the thermal oil heat exchange device 8 enters the heat exchanger II15 for heat exchange, and the circulating water of the heating system enters the heat exchanger II15 to exchange heat with the thermal oil, and then is sent to the heat user. The heat user adjusts the flow rate of the circulating water by adjusting the control valve IV22 according to the demand to achieve temperature control.

[0092] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A cross-seasonal long-term energy storage system using sand as a heat storage medium, characterized in that: The system includes a heat storage module, which is respectively connected to a photovoltaic power generation module, a steam power generation module and a heating module; The photovoltaic power generation module is used to convert light energy into electrical energy to provide energy for the heat storage module; The heat storage module is used to convert the electrical energy provided by the photovoltaic power generation module into thermal energy, and use sand as a heat storage medium to perform long-term energy storage across seasons, and use heat transfer oil to perform heat exchange with the steam power generation module and the heating module; The steam power generation module is used to perform a steam Rankine cycle when the temperature of the heat transfer oil rises to a threshold percentage of the failure temperature; The heating module is used to provide heating to heat users.

2. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 1 is characterized in that: The photovoltaic power generation module includes a photovoltaic assembly, a controller and an inverter connected in sequence; The photovoltaic module is used to convert light energy into electrical energy; The controller is used to regulate the direct current generated by the photovoltaic module and then transmit it to the inverter; The inverter is used to convert the regulated direct current into alternating current to supply power to the electric heating device in the heat storage module.

3. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 1 is characterized in that: The heat storage module comprises: an electric heating submodule, a sand energy storage submodule, and a heat transfer oil circulation submodule connected in sequence; the sand energy storage submodule and the heat transfer oil circulation submodule are respectively connected to a temperature measurement module I and a temperature measurement module II, and the temperature measurement module I is connected to a display alarm module; The electric heating submodule is connected to the photovoltaic power generation module and is used to convert electrical energy into thermal energy; The sand energy storage submodule contains sand for absorbing the heat provided by the electric heating submodule and raising the temperature; The temperature measuring module I and the temperature measuring module II are used to monitor the temperature of the sand and the temperature of the heat transfer oil respectively; The display alarm module is used to automatically alarm when the temperature of the sand rises to a threshold percentage of the failure temperature of the thermal oil; The heat transfer oil circulation submodule is filled with heat transfer oil, which heats up along with the sand. When the temperature measurement module II detects that the temperature of the heat transfer oil rises to a threshold percentage of its failure temperature, it is used to control the heat transfer oil to circulate in the module, thereby exchanging heat with the steam power generation module and the heating module.

4. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 3 is characterized in that: The heat transfer oil circulation submodule includes a heat transfer oil heat exchange device, a heat exchanger I, and a heat exchanger II; the heat transfer oil heat exchange device is used to circulate the heat transfer oil under the control of the temperature measurement module II, the heat exchanger I is used to exchange heat with the circulating water of the steam power generation module, and the heat exchanger II is used to exchange heat with the circulating water of the heating module; Preferably, the electric heating submodule adopts a serpentine design and is laid flat on the bottom of the sand energy storage submodule; Preferably, the heat transfer oil heat exchange device comprises a serpentine heat exchange pipe, and the serpentine heat exchange pipe is further bent to form a serpentine heat exchange curved surface; Preferably, the heat transfer oil heat exchange device is arranged in the sand energy storage submodule, and its heat exchange curved surface is arranged vertically to the electric heating submodule, and the heat transfer oil outlet and inlet of the heat transfer oil heat exchange device are located at the top of the sand energy storage submodule; Preferably, the long sides of the heat exchange curved surface correspond to at least one long side of the electric heating submodule.

5. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 4 is characterized in that: A three-way valve I is provided on the pipeline between the outlet of the heat transfer oil heat exchange device and the heat exchanger I, which has three inlets and outlets, namely, interface I, interface II and interface III; The interface I is connected to the outlet of the heat transfer oil heat exchange device via a heat transfer oil pipeline; The interface III is connected to the inlet of the heat transfer oil side part of the heat exchanger I through the heat transfer oil pipeline; The interface II is communicated with the inlet of the heat transfer oil side portion of the heat exchanger II via a heat transfer oil pipeline.

6. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 4 is characterized in that: A three-way valve II is provided on the pipeline connecting the outlet of the heat exchanger I back to the heat transfer oil heat exchange device, which has three inlets and outlets, namely, an interface IV, an interface V and an interface VI; The interface IV is connected to the inlet of the thermal oil heat exchange device via a thermal oil pipeline; The interface V is connected to the outlet of the heat transfer oil side portion of the heat exchanger I through the heat transfer oil pipeline; The interface VI is connected to the outlet of the heat transfer oil side of the heat exchanger II through a heat transfer pipeline, and is also provided with a control valve III for controlling the flow rate of the heat transfer oil circulation so that the temperature of the heat transfer oil does not exceed the failure temperature.

7. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 5 is characterized in that: The steam power generation module comprises: a steam superheater, a steam turbine, and a condenser connected in sequence; the inlet of the steam superheater is connected to a heat exchanger I, and a control valve II is provided on the pipeline between the two; the outlet of the condenser is connected to the heat exchanger I, and a circulating water pump I is provided on the pipeline between the two; the steam turbine is connected to the engine through a coupling; When the steam power generation module starts to run, the control valve II opens, and the circulating water pump I starts to run. The circulating water pump I is used to pump circulating water into the heat exchanger I to perform heat exchange with the heat transfer oil of the heat transfer oil circulation submodule. The control valve I controls the flow rate of the heat transfer oil so that the temperature of the heat transfer oil does not exceed the failure temperature, and at the same time, the heat of the heat exchange is kept smaller than the heat exchanged with the sand in the sand energy storage submodule; The steam after heat exchange is superheated by the steam superheater and then enters the steam turbine. The steam turbine is used to convert the superheated steam into mechanical energy and transmit it to the engine to generate electrical energy.

8. The cross-seasonal long-term energy storage system using sand as the heat storage medium according to claim 6 is characterized in that: The heating module includes: a circulating water pump II and a control valve IV; The circulating water pump II is arranged on the pipeline from the heat exchanger II to the heat user; The control valve IV is arranged on the pipeline from the heat user back to the heat exchanger II, and is used to control the flow rate of circulating water, so as to realize the temperature regulation of the heat user when heating the system.

9. A method for long-term energy storage across seasons using sand as a heat storage medium, characterized in that: In the heat storage and power generation mode, the method comprises: Interface I of the three-way valve I is connected to interface III, and interface IV of the three-way valve II is connected to interface V; the photovoltaic module, controller, inverter, electric heating device, temperature measurement module I, and display alarm module start to operate, so that the heat storage medium sand in the sand energy storage submodule starts to heat up; Before the temperature measuring module II detects that the temperature of the heat transfer oil has risen to the threshold percentage of the failure temperature, the control valves I, II, III and IV are all in a closed state, and the heat transfer oil circulation pump, circulating water pump I and II stop running. When the temperature of the heat transfer oil rises to the threshold percentage of the failure temperature, the temperature measuring module I controls the display alarm module to sound an alarm, and at the same time, the temperature measuring module II controls the heat transfer oil heat exchange device to start circulating, the control valve I opens, the heat transfer oil circulation pump starts running, and the heat transfer oil enters the heat exchanger I for heat exchange; When the steam power generation module starts to run, the control valve II is opened, the circulating water pump I starts to run, and the circulating water enters the heat exchanger I to exchange heat with the heat transfer oil. The flow rate of the heat transfer oil circulation submodule is controlled by the control valve I so that the temperature of the heat transfer oil does not exceed the failure temperature, while keeping the heat exchanged less than the heat exchanged with the sand in the sand energy storage submodule; the steam after heat exchange enters the steam superheater, obtains superheated steam and enters the steam turbine, performs work to generate mechanical energy, and transmits it to the generator to generate electrical energy.

10. The method for long-term energy storage across seasons using sand as a heat storage medium according to claim 9, characterized in that: The method further includes: In the heating mode, the interface I of the three-way valve I is connected to the interface II, the interface IV of the three-way valve II is connected to the interface VI, the photovoltaic module, the controller, the inverter, the electric heating device, the temperature measurement module I, and the display alarm module continue to operate, so that the heat storage medium sand in the sand energy storage submodule continues to absorb heat; Close control valve I and control valve II, and the circulating water pump I stops running. Open control valve III and control valve IV, and the thermal oil circulating pump and circulating water pump II start running. The heat transfer oil in the heat transfer oil heat exchange device enters the heat exchanger II for heat exchange, and the circulating water of the heating module enters the heat exchanger II for heat exchange with the heat transfer oil, and then is sent to the heat user; Heat users adjust control valve IV according to demand and achieve temperature control by changing the flow rate of circulating water.

Images