Integrated Wind-Solar Energy Storage System with Coupled Thermochemical Heat Storage and Its Operation Method

Abstract

The present invention discloses an integrated wind-solar energy storage system coupled with thermochemical energy storage and its operation method, which relates to the technical fields of wind-solar power generation and thermal energy storage. The integrated wind-solar energy storage system includes an energy storage system and an energy release system; when solar energy and wind energy are sufficient, the solar energy is used to drive a thermochemical energy storage reactor to store wind energy and solar energy; when solar energy and wind energy are insufficient and the electricity consumption is at a low valley, the wind energy, solar energy, and the thermal energy supplemented by an electric heater are uniformly stored in the solar-driven thermochemical energy storage reactor; when solar energy and wind energy are insufficient and the electricity consumption is at a peak, the energy release system converts the heat released by the reaction in the solar-driven thermochemical energy storage reactor into electric energy to meet the demand of the grid load. The system of the present invention couples and converts solar energy and wind energy into stable and high-quality electric energy, solves the problem of large fluctuations when using solar energy and wind energy for grid connection, and is an effective method for consuming clean energy and stabilizing grid fluctuations.

Description

Technical Field

[0001] The present invention relates to the technical fields of wind and solar power generation and thermal energy storage, and particularly relates to an integrated wind-solar energy storage system coupled with thermochemical heat storage and an operation method thereof. Background Art

[0002] Among renewable energy sources, solar energy and wind energy are the most widely used. However, the power generation of wind energy and solar energy itself has large volatility and intermittency, and directly connecting to the grid on a large scale will bring a huge impact on the safety and stability of the power system. The integrated wind-solar Carnot battery energy storage technology, as a very promising method in thermal energy storage technology, can convert the highly volatile solar energy and wind energy into thermal energy for storage, and then convert the thermal energy into stable electrical energy output, effectively solving the problem of difficult grid connection of renewable energy. However, there is currently a lack of design and operation control methods for the configuration of the integrated system of wind-solar power generation and Carnot battery energy storage. Summary of the Invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide an integrated wind-solar energy storage system coupled with thermochemical heat storage and an operation method thereof, which can effectively solve the problem of large fluctuations in wind-solar power generation and difficult grid connection, effectively absorb new energy and maintain the stability of the power grid.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] An integrated wind-solar energy storage system coupled with thermochemical heat storage, comprising an energy storage system and an energy release system; wherein,

[0006] The energy storage system includes a power grid system 1, an electric heater 2, a wind power generation set 3, a multi-stage charging compressor 4, a solar-driven thermochemical energy storage reactor 5, a charging recuperator 6, a charging expander 7, a charging low-temperature heat exchanger 8, a low-temperature cold storage tank 9, a No. 1 cold storage medium pump 10, a first valve 4-1, a second valve 4-2, and a third valve 4-3. Among them, the wind power generation set 3 converts wind energy into mechanical energy to drive the multi-stage charging compressor 4 to work. The normal-temperature and low-pressure working medium generates a high-temperature and high-pressure working medium after passing through the multi-stage charging compressor 4. A part of the high-temperature and high-pressure working medium at the outlet of the multi-stage charging compressor 4 first flows through the second valve 4-2, and the working medium heated and raised in temperature by the electric heater 2 flows through the third valve 4-3 and then mixes with another part of the high-temperature and high-pressure working medium after passing through the first valve 4-1 and enters the solar-driven thermochemical energy storage reactor 5 to carry out a chemical reaction process under the drive of solar energy. The medium-temperature and high-pressure working medium at the outlet of the solar-driven thermochemical energy storage reactor 5 releases heat in the charging recuperator 6. The normal-temperature and high-pressure working medium at the outlet of the charging recuperator 6 continues to do work in the charging expander 7 to generate a low-temperature and low-pressure working medium. The low-temperature and low-pressure working medium first absorbs the heat of the low-temperature cold storage medium in the charging low-temperature heat exchanger 8, and then absorbs the heat of the high-temperature working medium on the hot side in the charging recuperator 6. The outlet of the cold side of the charging recuperator 6 is a normal-temperature and low-pressure working medium, and the normal-temperature and low-pressure working medium enters the multi-stage charging compressor 4 to repeat this process. At the same time, the high-temperature cold storage medium in the low-temperature cold storage tank 9 passes through the No. 1 cold storage medium pump 10, and then releases heat in the charging low-temperature heat exchanger 8 to form a low-temperature cold storage medium and enters the low-temperature cold storage tank 9 to repeat this process;

[0007] The energy release system includes a power grid system 1, a solar-driven thermochemical energy storage reactor 5, a low-temperature cold storage tank 9, a discharging compressor 11, a multi-stage discharging expander 12, a discharging recuperator 13, a working medium-air heat exchanger 14, a discharging low-temperature heat exchanger 15, a generator 16, and a No. 2 cold storage medium pump 17. Among them, the ultra-low-temperature and low-pressure working medium generates a normal-temperature and high-pressure working medium after passing through the discharging compressor 11. The normal-temperature and high-pressure working medium absorbs heat in the discharging recuperator 13. Then, the medium-temperature and high-pressure working medium enters the solar-driven thermochemical energy storage reactor 5 to absorb the heat released during the chemical reaction process to generate a high-temperature and high-pressure working medium. Then, the high-temperature and high-pressure working medium enters the multi-stage discharging expander 12 to do work, generating mechanical energy and converting it into electrical energy in the generator 16 and outputting it to the power grid system 1. The high-temperature and high-pressure working medium continues to release heat in the discharging recuperator 13 after passing through the multi-stage discharging expander 12 to form a low-temperature and low-pressure working medium. Then, the low-temperature and low-pressure working medium releases heat to the outside air in the working medium-air heat exchanger 14, and then the working medium enters the discharging low-temperature heat exchanger 15 to release heat to the low-temperature cold storage medium, and finally an ultra-low-temperature and low-pressure working medium is obtained. The ultra-low-temperature and low-pressure working medium enters the discharging compressor 11 to repeat this process. At the same time, the low-temperature cold storage medium in the low-temperature cold storage tank 9 sequentially passes through the No. 2 cold storage medium pump 17 and the discharging low-temperature heat exchanger 15 to form a high-temperature cold storage medium and enters the low-temperature cold storage tank 9 to repeat this process.

[0008] Further, the solar-driven thermochemical energy storage reactor 5 uses calcium oxide and water as the chemical reaction process, and the operating temperature range is 80 - 615 °C; the low-temperature cold storage tank 9 uses organic matter heptane as the cold storage medium, and the operating temperature range is -20 - 25 °C.

[0009] Further, the circulating working fluid used in the integrated wind-solar energy storage system is nitrogen, the circulation form is the Brayton cycle, the highest working temperature is 600 °C, and the lowest working temperature is -10 °C.

[0010] Further, the multi-stage charging compressor 4 is composed of at least 4 stages of compressors, adopts a centrifugal compressor, and the comprehensive pressure ratio at the inlet and outlet reaches 9.6; the multi-stage discharging expander 12 is composed of at least 3 stages of expanders, adopts an axial flow expander, and the expansion ratio at the inlet and outlet reaches 7.2.

[0011] Further, the charging regenerator 6, the discharging regenerator 13, the working fluid-air heat exchanger 14, the charging low-temperature heat exchanger 8, and the discharging low-temperature heat exchanger 15 all adopt shell-and-tube heat exchangers.

[0012] Further, the solar-driven thermochemical energy storage reactor 5 includes 3 inlets and 3 outlets, and the low-temperature cold storage tank 9 includes 2 inlets and 2 outlets.

[0013] Further, the wind power generator set 3, the multi-stage charging compressor 4, and the charging expander 7 are coaxially connected; the discharging compressor 11, the multi-stage discharging expander 12, and the generator 16 are coaxially connected.

[0014] The operation method of the integrated wind-solar energy storage system with coupled thermochemical heat storage,

[0015] 1) When solar energy and wind energy are sufficient, the electric heater 2 connected to the power grid system 1 stops working. The mechanical energy output by the wind power generator set 3 serves as the input energy source for the multi-stage charging compressor 4 in the energy storage system, and solar energy serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor 5. The integrated wind-solar energy storage system with coupled thermochemical heat storage is used to convert wind energy and solar energy into the chemical energy of chemical products for storage. Specifically, open the first valve 4-1, close the second valve 4-2 and the third valve 4-3. The wind power generator set 3 drives the multi-stage charging compressor 4 to work. The high-temperature and high-pressure working fluid generated enters the solar-driven thermochemical energy storage reactor 5 through the first valve 4-1 and releases heat. At this time, wind energy and solar energy are converted into the chemical energy of the products in the chemical reaction and are finally stored in the solar-driven thermochemical energy storage reactor 5;

[0016] 2) When solar energy and wind energy are insufficient and the electricity consumption is at a low ebb, the mechanical energy output by the wind power generation unit 3 serves as the input energy source for the multi-stage charging compressor 4 in the energy storage system. The power grid system 1 transmits electric energy to drive the electric heater 2 to participate in heating the working medium. The electric energy input from solar energy, wind energy, and the power grid together serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor 5. The integrated wind-solar energy storage system with coupled thermochemical energy storage converts wind energy, solar energy, and electric energy into chemical energy of chemical products for storage. Specifically, open the first valve 4-1, the second valve 4-2, and the third valve 4-3. The wind power generation unit 3 drives the multi-stage charging compressor 4 to work. The normal-temperature and low-pressure working medium is heated and pressurized in the multi-stage charging compressor 4 and then divided into two paths. One path of the working medium enters the solar-driven thermochemical energy storage reactor 5 through the first valve 4-1, and the other path of the working medium also enters the solar-driven thermochemical energy storage reactor 5 after passing through the second valve 4-2, the electric heater 2, and the third valve 4-3. At this time, the high-temperature and high-pressure working medium and the heat provided by solar energy serve as the energy source for the solar-driven thermochemical energy storage reactor 5, promoting the progress of the chemical reaction, converting wind energy, solar energy, and electric energy into chemical energy of the products in the chemical reaction, and finally storing it in the solar-driven thermochemical energy storage reactor 5;

[0017] 3) When solar energy and wind energy are insufficient and the electricity consumption is at a peak, the energy release system participates in the operation at this time. The ultra-low temperature and low-pressure working medium is heated and pressurized by the discharge compressor 11 and then absorbs heat in the discharge recuperator 13. After that, the medium-temperature and high-pressure working medium enters the solar-driven thermochemical energy storage reactor 5, absorbs the heat released during the chemical reaction process to generate high-temperature and high-pressure working medium, and then the high-temperature and high-pressure working medium enters the multi-stage discharge expander 12 to do work, generating mechanical energy and converting it into electric energy in the generator 16 for output to the power grid system 1, realizing the conversion process from chemical energy to electric energy.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) Through the integration of wind-solar power generation and Carnot battery energy storage, the problem of large fluctuations in wind-solar power generation and difficult grid connection can be effectively solved, effectively accommodating new energy and maintaining the stability of the power grid;

[0020] (2) By adopting the thermochemical energy storage method, the cycle efficiency is higher and the energy storage density is higher compared with the traditional sensible heat or latent heat energy storage method;

[0021] (3) The working medium adopted is nitrogen, which has the advantages of high safety and good economy compared with other working media. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the integrated wind-solar energy storage system with coupled thermochemical energy storage of the present invention. Detailed Embodiments

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] As Figure 1 shown, the present invention provides an integrated wind-solar energy storage system coupled with thermochemical energy storage, including an energy storage system and an energy release system; wherein,

[0025] The energy storage system includes a power grid system 1, an electric heater 2, a wind power generation set 3, a multi-stage charging compressor 4, a solar-driven thermochemical energy storage reactor 5, a charging regenerator 6, a charging expander 7, a charging low-temperature heat exchanger 8, a low-temperature cold storage tank 9, a No. 1 cold storage medium pump 10, a first valve 4-1, a second valve 4-2 and a third valve 4-3; wherein, the wind power generation set 3 converts wind energy into mechanical energy to drive the multi-stage charging compressor 4 to work; the normal-temperature and low-pressure working medium generates a high-temperature and high-pressure working medium after passing through the multi-stage charging compressor 4. A part of the high-temperature and high-pressure working medium at the outlet of the multi-stage charging compressor 4 first flows through the second valve 4-2, and the working medium heated and raised in temperature by the electric heater 2 flows through the third valve 4-3 and then mixes with another part of the high-temperature and high-pressure working medium after passing through the first valve 4-1 and enters the solar-driven thermochemical energy storage reactor 5, and undergoes a chemical reaction process under the drive of solar energy. The medium-temperature and high-pressure working medium at the outlet of the solar-driven thermochemical energy storage reactor 5 releases heat in the charging regenerator 6. The normal-temperature and high-pressure working medium at the outlet of the charging regenerator 6 continues to do work in the charging expander 7 to generate a low-temperature and low-pressure working medium. The low-temperature and low-pressure working medium first absorbs the heat of the low-temperature cold storage medium in the charging low-temperature heat exchanger 8, and then absorbs the heat of the high-temperature working medium on the hot side in the charging regenerator 6. The outlet of the cold side of the charging regenerator 6 is a normal-temperature and low-pressure working medium, and the normal-temperature and low-pressure working medium enters the multi-stage charging compressor 4 to repeat this process; at the same time, the high-temperature cold storage medium in the low-temperature cold storage tank 9 passes through the No. 1 cold storage medium pump 10, and then releases heat in the charging low-temperature heat exchanger 8 to form a low-temperature cold storage medium and enters the low-temperature cold storage tank 9 to repeat this process;

[0026] The energy release system includes a power grid system 1, a solar-driven thermochemical energy storage reactor 5, a low-temperature cold storage tank 9, a discharge compressor 11, a multi-stage discharge expander 12, a discharge recuperator 13, a working fluid-air heat exchanger 14, a discharge low-temperature heat exchanger 15, a generator 16, and a No. 2 cold storage medium pump 17. Among them, the ultra-low temperature and low-pressure working fluid generates a normal temperature and high-pressure working fluid after passing through the discharge compressor 11. The normal temperature and high-pressure working fluid absorbs heat in the discharge recuperator 13. Then, the medium temperature and high-pressure working fluid enters the solar-driven thermochemical energy storage reactor 5 to absorb the heat released during the chemical reaction process and generates a high temperature and high-pressure working fluid. Then, the high temperature and high-pressure working fluid enters the multi-stage discharge expander 12 to do work, generating mechanical energy and converting it into electrical energy in the generator 16, which is output to the power grid system 1. After passing through the multi-stage discharge expander 12, the high temperature and high-pressure working fluid continues to release heat in the discharge recuperator 13 to form a low temperature and low-pressure working fluid. Then, the low temperature and low-pressure working fluid releases heat to the outside air in the working fluid-air heat exchanger 14. After that, the working fluid enters the discharge low-temperature heat exchanger 15 to release heat to the low-temperature cold storage medium, and finally obtains an ultra-low temperature and low-pressure working fluid. The ultra-low temperature and low-pressure working fluid enters the discharge compressor 11, repeating this process. At the same time, the low-temperature cold storage medium in the low-temperature cold storage tank 9 sequentially passes through the No. 2 cold storage medium pump 17 and the discharge low-temperature heat exchanger 15 to form a high-temperature cold storage medium and enters the low-temperature cold storage tank 9, repeating this process.

[0027] Further, the solar-driven thermochemical energy storage reactor 5 uses calcium oxide and water as the chemical reaction process, and the operating temperature range is 80 - 615 °C. The low-temperature cold storage tank 9 uses organic matter heptane as the cold storage medium, and the operating temperature range is -20 - 25 °C. In this way, on the one hand, the potential of thermochemical heat storage can be fully utilized to improve the heat storage density; on the other hand, the working temperature range can be expanded as much as possible to ensure the high efficiency of the energy storage system.

[0028] Further, the circulating working fluid used in the wind-solar integrated energy storage system is nitrogen, and the circulation form adopts the Brayton cycle, with the highest working temperature of 600 °C and the lowest working temperature of -10 °C. This can fully adapt to the temperature ranges of thermochemical heat storage and cold storage, reduce irreversible losses, and ensure the efficient and economic operation of the system.

[0029] Further, the multi-stage charge compressor 4 is at least composed of 4-stage compressors, adopting centrifugal compressors, and the comprehensive pressure ratio at the inlet and outlet reaches 9.6. The multi-stage discharge expander 12 is at least composed of 3-stage expanders, adopting axial flow expanders, and the expansion ratio at the inlet and outlet reaches 7.2. This can reduce the investment in unnecessary steam turbine equipment, lower the investment cost, and ensure the economy of the system.

[0030] Further, the charge recuperator 6, the discharge recuperator 13, the working fluid-air heat exchanger 14, the charge low-temperature heat exchanger 8, and the discharge low-temperature heat exchanger 15 all adopt shell-and-tube heat exchangers. This can ensure the high efficiency of the heat exchange process and is convenient for equipment maintenance at the same time.

[0031] Furthermore, the solar-driven thermochemical energy storage reactor 5 includes three inlets and three outlets, and the low-temperature cold storage tank 9 includes two inlets and two outlets. This can ensure that the same set of heat storage and cold storage equipment is shared during the heat storage and heat release processes, reducing costs.

[0032] Furthermore, the wind power generation unit 3, the multi-stage charging compressor 4, and the charging expander 7 are coaxially connected; the discharging compressor 11, the multi-stage discharging expander 12, and the generator 16 are coaxially connected. This can ensure the net input and output power, reduce unnecessary losses, and at the same time ensure that the equipment operates at the same frequency, and can also avoid unnecessary equipment investment, ensuring the technical economy of the system.

[0033] The operation method of the integrated wind-solar energy storage system with coupled thermochemical energy storage

[0034] 1) When solar energy and wind energy are sufficient, the electric heater 2 connected to the power grid system 1 stops working. The mechanical energy output by the wind power generation unit 3 serves as the input energy source for the multi-stage charging compressor 4 in the energy storage system, and solar energy serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor 5. The integrated wind-solar energy storage system with coupled thermochemical energy storage is used to convert wind energy and solar energy into the chemical energy of chemical products for storage; specifically, the first valve 4-1 is opened, the second valve 4-2 and the third valve 4-3 are closed, the wind power generation unit 3 drives the multi-stage charging compressor 4 to work, and the generated high-temperature and high-pressure working medium enters the solar-driven thermochemical energy storage reactor 5 through the first valve 4-1 to release heat. At this time, the wind energy and solar energy are converted into the chemical energy of the products in the chemical reaction and are finally stored in the solar-driven thermochemical energy storage reactor 5;

[0035] 2) When solar energy and wind energy are insufficient and the electricity consumption is at a low valley, the mechanical energy output by the wind power generating unit serves as the input energy source for the multi-stage charging compressor 4 in the energy storage system. The power grid system 1 transmits electric energy to drive the electric heater 2 to participate in heating the working medium. The electric energy input by solar energy, wind energy, and the power grid together serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor 5. The integrated wind-solar energy storage system with coupled thermochemical energy storage converts wind energy, solar energy, and electric energy into the chemical energy of chemical products for storage. Specifically, the first valve 4-1, the second valve 4-2, and the third valve 4-3 are opened. The wind power generating unit 3 drives the multi-stage charging compressor 4 to work. The normal-temperature and low-pressure working medium is heated and pressurized in the multi-stage charging compressor 4 and then divided into two paths. One path of the working medium enters the solar-driven thermochemical energy storage reactor 5 through the first valve 4-1, and the other path of the working medium also enters the solar-driven thermochemical energy storage reactor 5 after passing through the second valve 4-2, the electric heater 2, and the third valve 4-3. At this time, the high-temperature and high-pressure working medium and the heat provided by solar energy serve as the energy source for the solar-driven thermochemical energy storage reactor 5, promoting the progress of the chemical reaction, converting wind energy, solar energy, and electric energy into the chemical energy of the products in the chemical reaction, and finally storing it in the solar-driven thermochemical energy storage reactor 5;

[0036] 3) When solar energy and wind energy are insufficient and the electricity consumption is at a peak, the energy release system participates in the operation at this time. The ultra-low temperature and low-pressure working medium is heated and pressurized by the discharge compressor 11 and then absorbs heat in the discharge recuperator 13. After that, the medium-temperature and high-pressure working medium enters the solar-driven thermochemical energy storage reactor 5, absorbs the heat released during the chemical reaction process to generate high-temperature and high-pressure working medium, and then the high-temperature and high-pressure working medium enters the multi-stage discharge expander 12 to do work, generating mechanical energy and converting it into electric energy in the generator 16 for output to the power grid system 1, realizing the conversion process from chemical energy to electric energy.

Claims

1. A wind-solar integrated energy storage system coupled with thermochemical energy storage, characterized in that The described wind-solar integrated energy storage system includes an energy storage system and an energy release system; among them, The energy storage system includes a power grid system (1), an electric heater (2), a wind power generation set (3), a multi-stage charging compressor (4), a solar-driven thermochemical energy storage reactor (5), a charging recuperator (6), a charging expander (7), a charging low-temperature heat exchanger (8), a low-temperature cold storage tank (9), a No. 1 cold storage medium pump (10), a first valve (4-1), a second valve (4-2), and a third valve (4-3); among them, the wind power generation set (3) converts wind energy into mechanical energy to drive the multi-stage charging compressor (4) to work; the normal-temperature and low-pressure working medium generates a high-temperature and high-pressure working medium after passing through the multi-stage charging compressor (4). A part of the high-temperature and high-pressure working medium at the outlet of the multi-stage charging compressor (4) first flows through the second valve (4-2), and the working medium heated and raised in temperature by the electric heater (2) flows through the third valve (4-3) and then mixes with another part of the high-temperature and high-pressure working medium after passing through the first valve (4-1) and enters the solar-driven thermochemical energy storage reactor (5) to carry out a chemical reaction process under the drive of solar energy. The medium-temperature and high-pressure working medium at the outlet of the solar-driven thermochemical energy storage reactor (5) releases heat in the charging recuperator (6). The normal-temperature and high-pressure working medium at the outlet of the charging recuperator (6) continues to do work in the charging expander (7) to generate a low-temperature and low-pressure working medium. The low-temperature and low-pressure working medium first absorbs the heat of the low-temperature cold storage medium in the charging low-temperature heat exchanger (8), and then absorbs the heat of the high-temperature working medium on the hot side in the charging recuperator (6). The cold-side outlet of the charging recuperator (6) is a normal-temperature and low-pressure working medium, and the normal-temperature and low-pressure working medium enters the multi-stage charging compressor (4) to repeat this process; at the same time, the high-temperature cold storage medium in the low-temperature cold storage tank (9) passes through the No. 1 cold storage medium pump (10), and then releases heat in the charging low-temperature heat exchanger (8) to form a low-temperature cold storage medium and enters the low-temperature cold storage tank (9); The energy release system includes a power grid system (1), a solar-driven thermochemical energy storage reactor (5), a low-temperature cold storage tank (9), a discharge compressor (11), a multi-stage discharge expander (12), a discharge recuperator (13), a working fluid-air heat exchanger (14), a discharge low-temperature heat exchanger (15), a generator (16), and a No. 2 cold storage medium pump (17); among them, the ultra-low temperature and low-pressure working fluid generates a normal temperature and high-pressure working fluid after passing through the discharge compressor (11), the normal temperature and high-pressure working fluid absorbs heat in the discharge recuperator (13), and then the medium temperature and high-pressure working fluid enters the solar-driven thermochemical energy storage reactor (5) to absorb the heat released during the chemical reaction process to generate a high temperature and high-pressure working fluid. Then, the high temperature and high-pressure working fluid enters the multi-stage discharge expander (12) to do work, generating mechanical energy and converting it into electrical energy in the generator (16) and outputting it to the power grid system (1). After passing through the multi-stage discharge expander (12), the high temperature and high-pressure working fluid continues to release heat in the discharge recuperator (13) to form a low temperature and low-pressure working fluid. Then, the low temperature and low-pressure working fluid releases heat to the external air in the working fluid-air heat exchanger (14), and then the working fluid enters the discharge low-temperature heat exchanger (15) to release heat to the low-temperature cold storage medium, and finally an ultra-low temperature and low-pressure working fluid is obtained. The ultra-low temperature and low-pressure working fluid enters the discharge compressor (11) to repeat this process; at the same time, the low-temperature cold storage medium in the low-temperature cold storage tank (9) sequentially passes through the No. 2 cold storage medium pump (17) and the discharge low-temperature heat exchanger (15) to form a high-temperature cold storage medium and enter the low-temperature cold storage tank (9).

2. The integrated wind-solar energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The solar-driven thermochemical energy storage reactor (5) uses calcium oxide and water as the chemical reaction process, and the operating temperature range is 80 - 615 °C; the low-temperature cold storage tank (9) uses organic matter heptane as the cold storage medium, and the operating temperature range is -20 - 25 °C.

3. A wind-solar integrated energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The circulating working fluid used in the wind-solar integrated energy storage system is nitrogen, the circulation form adopts the Brayton cycle, the highest working temperature is 600 °C, and the lowest working temperature is -10 °C.

4. A wind-solar integrated energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The multi-stage charge compressor (4) is composed of at least 4 stages of compressors, adopts a centrifugal compressor, and the comprehensive pressure ratio at the inlet and outlet reaches 9.6; the multi-stage discharge expander (12) is composed of at least 3 stages of expanders, adopts an axial flow expander, and the expansion ratio at the inlet and outlet reaches 7.

2.

5. The integrated wind-solar energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The charge recuperator (6), the discharge recuperator (13), the working fluid-air heat exchanger (14), the charge low-temperature heat exchanger (8), and the discharge low-temperature heat exchanger (15) all adopt shell-and-tube heat exchangers.

6. The integrated wind-solar energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The solar-driven thermochemical energy storage reactor (5) includes 3 inlets and 3 outlets, and the low-temperature cold storage tank (9) includes 2 inlets and 2 outlets.

7. A wind-solar integrated energy storage system with coupled thermochemical energy storage according to claim 1, characterized in that: The wind power generating set (3), the multi-stage charge compressor (4), and the charge expander (7) are coaxially connected; the discharge compressor (11), the multi-stage discharge expander (12), and the generator (16) are coaxially connected.

8. The operation method of a wind-solar integrated energy storage system with coupled thermochemical heat storage according to any one of claims 1 to 7, characterized in that: 1) When solar energy and wind energy are sufficient, the electric heater (2) connected to the power grid system (1) stops working. The mechanical energy output by the wind power generation unit (3) serves as the input energy source for the multi-stage charging compressor (4) in the energy storage system, and solar energy serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor (5). The integrated wind-solar energy storage system with coupled thermochemical heat storage converts wind energy and solar energy into the chemical energy of chemical products for storage. Specifically, open the first valve (4-1), close the second valve (4-2) and the third valve (4-3). The wind power generation unit (3) drives the multi-stage charging compressor (4) to work. The high-temperature and high-pressure working medium generated enters the solar-driven thermochemical energy storage reactor (5) through the first valve (4-1) to release heat. At this time, the solar energy and wind energy are converted into the chemical energy of the products in the chemical reaction and finally stored in the solar-driven thermochemical energy storage reactor (5). 2) When solar energy and wind energy are insufficient and electricity consumption is at a low ebb, the mechanical energy output by the wind power generation unit (3) serves as the input energy source for the multi-stage charging compressor (4) in the energy storage system. The power grid system (1) transmits electric energy to drive the electric heater (2) to participate in heating the working medium. The electric energy input by solar energy, wind energy and the power grid together serves as the energy source for the chemical reaction in the solar-driven thermochemical energy storage reactor (5). The integrated wind-solar energy storage system with coupled thermochemical heat storage converts wind energy, solar energy and electric energy into the chemical energy of chemical products for storage. Specifically, open the first valve (4-1), the second valve (4-2) and the third valve (4-3). The wind power generation unit (3) drives the multi-stage charging compressor (4) to work. The normal-temperature and low-pressure working medium is heated and pressurized in the multi-stage charging compressor (4) and then divided into two paths. One path of the working medium enters the solar-driven thermochemical energy storage reactor (5) through the first valve (4-1), and the other path of the working medium also enters the solar-driven thermochemical energy storage reactor (5) after passing through the second valve (4-2), the electric heater (2) and the third valve (4-3). At this time, the high-temperature and high-pressure working medium and the heat provided by solar energy serve as the energy source of the solar-driven thermochemical energy storage reactor (5) to promote the chemical reaction, and convert wind energy, solar energy and electric energy into the chemical energy of the products in the chemical reaction and finally store it in the solar-driven thermochemical energy storage reactor (5). 3) When solar energy and wind energy are insufficient and electricity consumption is at a peak, the energy release system participates in the operation at this time. The ultra-low temperature and low-pressure working medium is heated and pressurized by the discharge compressor (11) and then absorbs heat in the discharge recuperator (13). Then the medium-temperature and high-pressure working medium enters the solar-driven thermochemical energy storage reactor (5), absorbs the heat released during the chemical reaction process to generate a high-temperature and high-pressure working medium. Then the high-temperature and high-pressure working medium enters the multi-stage discharge expander (12) to do work, generating mechanical energy and converting it into electric energy in the generator (16) and outputting it to the power grid system (1), realizing the conversion process from chemical energy to electric energy.

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