Heat pump and steam energy storage combined energy storage system and energy storage method

Abstract

The invention discloses an energy storage system and method combining a heat pump and steam energy storage, and relates to the field of energy storage, the energy storage system comprises a heat pump subsystem used for being electrically connected with a renewable energy power generation system and capable of generating steam, and a steam energy storage subsystem used for being connected with the heat pump subsystem and storing steam heat energy generated by the heat pump subsystem, the power generation subsystem is connected with the steam energy storage subsystem, and the steam energy storage subsystem can release saturated steam and enter the power generation subsystem. In the energy storage mode, the renewable energy power generation system supplies power to electric parts of the heat pump subsystem, and the heat pump subsystem generates steam; the steam energy storage subsystem stores steam heat energy generated by the heat pump subsystem; in the energy release mode, the steam energy storage subsystem releases saturated steam, and the saturated steam enters the power generation subsystem and drives the power generation subsystem to generate power. The system is safe and environment-friendly, can provide rotational inertia for a power grid, and is long in mechanical life, high in response speed, flexible in system site selection, low in full-life-cycle cost and short in construction cycle.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to an energy storage system and method that combines heat pumps and steam energy storage. Background Technology

[0002] Fossil fuel combustion is a major source of pollutants such as carbon dioxide, nitrogen oxides, and particulate matter, and its cumulative effects pose a serious threat to the stability of the climate system. Among renewable energy power generation technologies, wind power and photovoltaic power generation have become one of the main directions of energy transition due to their advantages such as abundant resources, low carbon emission intensity throughout their life cycle, continuously declining cost per kilowatt-hour, and short construction period.

[0003] However, the inherent weather dependence of wind and solar energy leads to significant fluctuations in their power output. To ensure grid supply and demand balance in scenarios with a high proportion of renewable energy, it is urgent to configure large-scale, highly reliable energy storage systems to smooth power fluctuations and improve the absorption of new energy. Among the mainstream energy storage technologies currently applicable to wind and solar power bases, electrochemical energy storage technology is limited by the aging mechanism of electrode materials, resulting in problems such as limited cycle life, irreversible capacity decay, and high cost; compressed air energy storage technology depends on specific geological structures, has poor site selection flexibility, high initial investment, long construction period, and long dynamic response time, making it difficult to meet the needs of high-frequency power regulation; electrically heated molten salt thermal storage technology has the risk of freezing and blockage, and high-temperature molten salt is highly corrosive to metal materials, imposing stringent requirements on equipment sealing and material durability.

[0004] Therefore, there is an urgent need to develop a new type of long-term energy storage technology that is low in construction cost, high in operational safety, fast in response speed, and not constrained by geographical conditions, in order to support the large-scale and high-quality development of wind and solar power bases and accelerate the construction of a new power system based on new energy sources. Summary of the Invention

[0005] The purpose of this invention is to provide an energy storage system and method that combines heat pumps and steam energy storage to solve the problems existing in the prior art. The energy storage system proposed in this invention has the characteristics of being safe and environmentally friendly, having a long mechanical life, fast response speed, flexible system site selection, not being constrained by geographical conditions, low total life cycle cost, short construction period, and being able to provide rotational inertia for the power grid.

[0006] To achieve the above objectives, the present invention provides the following solution: This invention provides an energy storage system combining a heat pump and steam energy storage, comprising: A heat pump subsystem, which is electrically connected to a renewable energy power generation system and is capable of generating steam; A steam energy storage subsystem, which is used to connect to the heat pump subsystem and store the steam thermal energy generated by the heat pump subsystem; The system includes a power generation system that can be connected to the steam energy storage subsystem. The steam energy storage subsystem can release saturated steam, which can enter the power generation system and drive it to generate electricity.

[0007] Preferably, the system further includes a first isolation valve and a second isolation valve, wherein the first isolation valve is used to be installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; and the second isolation valve is used to be installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the power generation system.

[0008] Preferably, the system further includes a first regulating valve and a second regulating valve. The first regulating valve is used to be installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; the second regulating valve is used to be installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the power generation system.

[0009] Preferably, the system further includes a water storage tank, a condenser, a condensate pump, and a feedwater pump. The inlet and outlet of the water storage tank are connected to the outlet of the condensate pump and the inlet of the feedwater pump, respectively. The outlet of the feedwater pump is connected to the heat pump subsystem and can transport the water medium in the water storage tank to the heat pump subsystem. When the water medium flows through the heat pump subsystem, it can absorb heat and vaporize into steam. The condenser is used to connect to the power generation system. The exhaust steam generated by the power generation system after generating electricity under the action of the saturated steam can enter the condenser and be condensed into condensate by the condenser. The condensate pump is used to connect to the condenser and can transport the condensate in the condenser to the water storage tank.

[0010] Preferably, the system further includes a third isolation valve and a fourth isolation valve, wherein the third isolation valve is used to install on the pipeline between the outlet of the condenser and the inlet of the water storage tank; and the fourth isolation valve is used to install on the pipeline between the outlet of the water storage tank and the water inlet of the heat pump subsystem.

[0011] Preferably, the system further includes a third regulating valve and a fourth regulating valve, wherein the third regulating valve is used to install on the pipeline between the outlet of the condenser and the inlet of the water storage tank; and the fourth regulating valve is used to install on the pipeline between the outlet of the water storage tank and the water inlet of the heat pump subsystem.

[0012] Preferably, the heat pump subsystem is a multi-stage heat pump subsystem.

[0013] Preferably, the heat pump subsystem includes an evaporator, an intermediate heat exchanger, a condenser, a first compressor, a second compressor, a first expansion valve, a second expansion valve, and a steam compressor. The first compressor, the second compressor, and the steam compressor are all electrically connected to the renewable energy power generation system. The evaporator has a first heat exchange channel and a second heat exchange channel, the intermediate heat exchanger has a third heat exchange channel and a fourth heat exchange channel, and the condenser has a fifth heat exchange channel and a sixth heat exchange channel. The outlet of the second heat exchange channel, the inlet of the first compressor, the outlet of the first compressor, the inlet of the third heat exchange channel, the outlet of the third heat exchange channel, the inlet of the first expansion valve, the outlet of the first expansion valve, and the inlet of the second heat exchange channel are sequentially connected to form a first circulation channel. The outlet of the fourth heat exchange channel and the second compressor... The inlet of the first heat exchanger, the outlet of the second compressor, the inlet of the fifth heat exchange channel, the outlet of the fifth heat exchange channel, the inlet of the second expansion valve, the outlet of the second expansion valve, and the inlet of the fourth heat exchange channel are sequentially connected to form a second circulation channel; the outlet of the water storage tank, the inlet of the sixth heat exchange channel, the outlet of the sixth heat exchange channel, and the steam inlet of the steam energy storage subsystem are sequentially connected; the first heat exchange channel is used to introduce ambient air; the lower-stage heat pump working fluid flowing through the second heat exchange channel can absorb the heat of the ambient air; the lower-stage heat pump working fluid flowing through the third heat exchange channel heats the upper-stage heat pump working fluid flowing through the fourth heat exchange channel; the upper-stage heat pump working fluid flowing through the fifth heat exchange channel can heat the water working fluid flowing through the sixth heat exchange channel and vaporize the water working fluid into steam.

[0014] Preferably, the steam energy storage subsystem includes a steam accumulator, a water supply valve, and a drain valve. The steam inlet of the steam accumulator is connected to the steam outlet of the heat pump subsystem, and the steam outlet of the steam accumulator is connected to the steam inlet of the power generation system. The water supply valve is installed at the water inlet end of the steam accumulator, and the drain valve is installed at the water outlet end of the steam accumulator. The power generation system includes a steam turbine and a generator. The steam inlet of the steam turbine is connected to the steam outlet of the steam storage subsystem. The output end of the steam turbine is connected to the input end of the generator. The exhaust steam outlet of the steam turbine is connected to the exhaust steam inlet of the condenser.

[0015] The present invention also provides an energy storage method based on the aforementioned energy storage system combining heat pump and steam energy storage, comprising the following steps: When the system is in energy storage mode, the renewable energy power generation system supplies power to the electrical components of the heat pump subsystem, and the heat pump subsystem generates steam; the steam energy storage subsystem stores the steam heat energy generated by the heat pump subsystem. When the system is in energy release mode, the steam energy storage subsystem releases saturated steam, which then enters the power generation system and drives the power generation system to generate electricity.

[0016] The present invention achieves the following technical effects compared to the prior art: This invention provides an energy storage system and method combining a heat pump and steam energy storage. The energy storage system includes: a heat pump subsystem, which is electrically connected to a renewable energy power generation system and capable of generating steam; a steam energy storage subsystem, which is connected to the heat pump subsystem and stores the steam thermal energy generated by the heat pump subsystem; and a power generation system, which is connected to the steam energy storage subsystem and capable of releasing saturated steam, which can then enter the power generation system and drive it to generate electricity. The energy storage method includes, when the system is in energy storage mode, supplying power to the electrical components of the heat pump subsystem through the renewable energy power generation system to generate steam through the heat pump subsystem; storing the steam thermal energy generated by the heat pump subsystem through the steam energy storage subsystem; and when the system is in energy release mode, causing the steam energy storage subsystem to release saturated steam, which then enters the power generation system and drives it to generate electricity.

[0017] The renewable energy power generation system supplies power to the electrical equipment in the heat pump subsystem, converting the electrical energy of the renewable energy power generation system into steam heat energy, which is stored in the steam energy storage subsystem. When the system releases energy, the steam energy storage subsystem releases saturated steam to drive the power generation system. The core equipment of the heat pump subsystem, steam energy storage subsystem, and power generation system are all mature industrial products with long mechanical life. The steam energy storage subsystem has a large energy storage capacity, enabling long-term energy storage without capacity decay during use. The steam generated by the heat pump subsystem directly drives the power generation system, improving response speed. The system offers flexible site selection, is not constrained by geographical conditions, and can reduce construction investment costs and shorten the construction period. The system can use water / steam as the energy storage medium, is safe and environmentally friendly, has low requirements for equipment sealing and material durability, has low total life cycle cost, and can provide rotational inertia for grid operation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the energy storage system combining a heat pump and steam energy storage provided in Example 1; In the diagram: 100. Energy storage system combining heat pump and steam storage; 1. Evaporator; 2. Intermediate heat exchanger; 3. Condenser; 4. First compressor; 5. Second compressor; 6. First expansion valve; 7. Second expansion valve; 8. Water storage tank; 9. Steam compressor; 10. Steam accumulator; 11. Steam turbine; 12. Make-up water valve; 13. Drain valve; 14. Second isolation valve; 15. Second regulating valve; 16. First regulating valve; 17. First isolation valve; 18. Third isolation valve; 19. Third regulating valve; 20. Fourth isolation valve; 21. Fourth regulating valve; 22. Feed water pump; 23. Condensate pump; 24. Condenser; 25. Generator; 26. Renewable energy power generation system. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "center," "longitudinal," "transverse," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "clockwise," and "counterclockwise," etc., indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Additionally, it should be noted that in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] The purpose of this invention is to provide an energy storage system and method that combines heat pumps and steam energy storage to solve the problems existing in the prior art. It is safe and environmentally friendly, has a long mechanical life, fast response speed, flexible system site selection, is not constrained by geographical conditions, has low total life cycle cost, and short construction period.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1 like Figure 1 As shown, this embodiment provides an energy storage system 100 combining a heat pump and steam energy storage, including: A heat pump subsystem is used to be electrically connected to the renewable energy power generation system 26 and is capable of generating steam. The steam energy storage subsystem is used to connect to the heat pump subsystem and store the steam thermal energy generated by the heat pump subsystem. The power generation system can be connected to the steam energy storage subsystem. The steam energy storage subsystem can release saturated steam, which can then enter the power generation system and drive it to generate electricity.

[0025] The renewable energy power generation system 26 supplies power to the electrical equipment in the heat pump subsystem, converting the electrical energy of the renewable energy power generation system 26 into steam heat energy, which is then stored in the steam energy storage subsystem. When the system releases energy, the steam energy storage subsystem releases saturated steam to drive the power generation system. The core equipment of the heat pump subsystem, steam energy storage subsystem, and power generation system are all mature industrial products with long mechanical lifespans. The steam energy storage subsystem has a large energy storage capacity, enabling long-term energy storage without capacity decay during use. The steam generated by the heat pump subsystem directly drives the power generation system, improving response speed. The system offers flexible site selection, is not constrained by geographical conditions, and can reduce construction investment costs and shorten the construction period. The system can use water / steam as the energy storage medium, is safe and environmentally friendly, has low requirements for equipment sealing and material durability, low total life cycle cost, and can provide rotational inertia to the power grid.

[0026] In some implementations, the renewable energy generation system 26 includes a wind power generation system and a photovoltaic power generation system, wherein the surplus electricity from the wind power generation system and / or the photovoltaic power generation system is used to power a heat pump subsystem to convert electrical energy into steam heat energy, and is stably stored through a steam energy storage subsystem.

[0027] In some embodiments, a second isolation valve 14 and a first isolation valve 17 are also included. The first isolation valve 17 is installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; the second isolation valve 14 is installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the power generation system. The second isolation valve 14 and the first isolation valve 17 are used to control the on / off state of the corresponding pipelines, so that the system switches between energy storage mode and energy release mode.

[0028] In some embodiments, a first regulating valve 16 and a second regulating valve 15 are also included. The first regulating valve 16 is installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; the second regulating valve 15 is installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the generator system. The steam intake of the steam accumulator 10 is controlled by adjusting the opening of the first regulating valve 16; the output power of the generator 25 is controlled by adjusting the opening of the second regulating valve 15.

[0029] In some embodiments, the system also includes a water storage tank 8, a condenser 24, a condensate pump 23, and a feedwater pump 22. The inlet and outlet of the water storage tank 8 are connected to the outlet of the condensate pump 23 and the inlet of the feedwater pump 22, respectively. The outlet of the feedwater pump 22 is connected to the heat pump subsystem and can transport the water working medium in the water storage tank 8 to the heat pump subsystem. When the water working medium flows through the heat pump subsystem, it can absorb heat and vaporize into steam. The condenser 24 is used to connect to the power generation system. The exhaust steam generated by the power generation system after generating electricity under the action of saturated steam can enter the condenser 24 and be condensed into condensate by the condenser 24. The condensate pump 23 is used to connect to the condenser 24 and can transport the condensate in the condenser 24 to the water storage tank 8.

[0030] In some embodiments, a third isolation valve 18 and a fourth isolation valve 20 are also included. The third isolation valve 18 is installed on the pipeline between the outlet of the condenser 24 and the inlet of the water storage tank 8; the fourth isolation valve 20 is installed on the pipeline between the outlet of the water storage tank 8 and the water inlet of the heat pump subsystem. The third isolation valve 18 and the fourth isolation valve 20 are used to control the on / off state of the corresponding pipelines.

[0031] In some embodiments, a third regulating valve 19 and a fourth regulating valve 21 are also included. The third regulating valve 19 is installed on the pipeline between the outlet of the condenser 24 and the inlet of the water storage tank 8; the fourth regulating valve 21 is installed on the pipeline between the outlet of the water storage tank 8 and the water inlet of the heat pump subsystem. The third regulating valve 19 and the fourth regulating valve 21 can regulate the pressure of the corresponding pipelines.

[0032] In some implementations, the heat pump subsystem is a multi-stage heat pump subsystem, ensuring that the water working fluid is completely vaporized before entering the steam accumulator 10, thereby significantly improving the utilization rate of the exhaust steam of the heat pump subsystem.

[0033] In some embodiments, the heat pump subsystem includes an evaporator 1, an intermediate heat exchanger 2, a condenser 3, a first compressor 4, a second compressor 5, a first expansion valve 6, a second expansion valve 7, and a steam compressor 9. The first compressor 4, the second compressor 5, and the steam compressor 9 are all electrically connected to the renewable energy power generation system 26. The evaporator 1 has a first heat exchange channel and a second heat exchange channel, the intermediate heat exchanger 2 has a third heat exchange channel and a fourth heat exchange channel, and the condenser 3 has a fifth heat exchange channel and a sixth heat exchange channel. The outlet of the second heat exchange channel, the inlet of the first compressor 4, the outlet of the first compressor 4, the inlet of the third heat exchange channel, the outlet of the third heat exchange channel, the inlet of the first expansion valve 6, the outlet of the first expansion valve 6, and the inlet of the second heat exchange channel are sequentially connected to form a first circulation channel. The outlet of the fourth heat exchange channel, the inlet of the second compressor 5, the outlet of the second compressor 5, the inlet of the fifth heat exchange channel, the outlet of the fifth heat exchange channel, the inlet of the second expansion valve 7, the outlet of the second expansion valve 7, and the inlet of the fourth heat exchange channel are connected in sequence to form the second circulation channel; the outlet of the water storage tank 8, the inlet of the sixth heat exchange channel, the outlet of the sixth heat exchange channel, and the steam inlet of the steam energy storage subsystem are connected in sequence; the first heat exchange channel is used to introduce ambient air; the lower-stage heat pump working fluid flowing through the second heat exchange channel can absorb heat from the ambient air; the lower-stage heat pump working fluid flowing through the third heat exchange channel heats the upper-stage heat pump working fluid flowing through the fourth heat exchange channel; the upper-stage heat pump working fluid flowing through the fifth heat exchange channel can heat the water working fluid flowing through the sixth heat exchange channel and vaporize the water working fluid into steam.

[0034] In some embodiments, the steam storage subsystem includes a steam accumulator 10, a water supply valve 12, and a drain valve 13. The steam inlet of the steam accumulator 10 is connected to the steam outlet of the heat pump subsystem, and the steam outlet of the steam accumulator 10 is connected to the steam inlet of the power generation system. The water supply valve 12 is installed at the inlet end of the steam accumulator 10, and the drain valve 13 is installed at the outlet end of the steam accumulator 10. The water supply valve 12 and the drain valve 13 are used to maintain water level and water quality.

[0035] In some embodiments, the steam accumulator 10 is an insulated pressure vessel with deoxygenation capabilities. It stores saturated water and stores both sensible and latent heat by injecting high-temperature, high-pressure steam, causing the water temperature and pressure inside the tank to rise synchronously. The steam accumulator 10 operates at a pressure of 3.0 MPa, corresponding to a saturated water temperature of 235°C. The usable steam ratio reaches 90%-95%, significantly improving energy storage efficiency.

[0036] In some embodiments, the power generation system includes a steam turbine 11 and a generator 25. The steam inlet of the steam turbine 11 is connected to the steam outlet of the steam storage subsystem, the output end of the steam turbine 11 is connected to the input end of the generator 25, and the exhaust steam outlet of the steam turbine 11 is connected to the exhaust steam inlet of the condenser 24.

[0037] In some embodiments, the steam turbine 11 is a saturated steam turbine 11. The saturated steam turbine 11 is a condensing unit, with saturated steam having a dryness fraction ≥ 0.95 as the inlet steam and an exhaust pressure of 9 kPa; the condenser 24 is air-cooled.

[0038] In some embodiments, the first isolation valve 17, the third isolation valve 18, and the fourth isolation valve 20 are all electrically operated shut-off valves.

[0039] In some embodiments, the outlet of the water pump 22 is connected to the inlet of the fourth isolation valve 20; the outlet of the fourth isolation valve 20 is connected to the inlet of the fourth regulating valve 21; and the outlet of the fourth regulating valve 21 is connected to the cold side inlet of the condenser 3 (the inlet of the sixth heat exchange channel).

[0040] In some embodiments, the inlet of the first isolation valve 17 is connected to the outlet of the steam compressor 9; the outlet of the first isolation valve 17 is connected to the inlet of the first regulating valve 16; the outlet of the first regulating valve 16 is connected to the steam inlet of the steam accumulator 10; the steam outlet of the steam accumulator 10 is connected to the inlet of the second isolation valve 14; the outlet of the second isolation valve 14 is connected to the inlet of the second regulating valve 15; a water supply valve 12 is provided on the water supply pipe of the steam accumulator 10; and a drain valve 13 is provided on the drain pipe of the steam accumulator 10.

[0041] In some embodiments, the steam inlet of the steam turbine 11 is connected to the outlet of the second regulating valve 15; the steam turbine 11 is coaxially connected to the generator 25; the exhaust steam outlet of the steam turbine 11 is connected to the exhaust steam inlet of the condenser 24; the outlet of the condenser 24 is connected to the inlet of the condensate pump 23; the outlet of the condensate pump 23 is connected to the inlet of the third isolation valve 18; the outlet of the third isolation valve 18 is connected to the inlet of the third regulating valve 19; and the outlet of the third regulating valve 19 is connected to the inlet of the water storage tank 8.

[0042] In some implementations, a heat pump working fluid with a high environmentally friendly critical temperature is used, such as: low GWP fluoroolefin (HFO / HCFO) R1233zd(E): critical temperature is 166°C, GWP = 1, and ODP is close to 0.

[0043] This embodiment aims to address the shortcomings of existing technologies in terms of cost, geographical adaptability, response speed, and long-term operational reliability. Specifically, this embodiment constructs an energy quality regulation path centered on heat pump heating and steam pressure enhancement, combined with a high-temperature, high-pressure saturated water / steam phase change latent heat storage mechanism, to achieve efficient capture and cross-period release of excess electrical energy from wind and solar power generation. Furthermore, through a heat-to-power conversion device, the stored thermal energy is converted into high-quality electrical energy on demand, thereby providing the power grid with stable power regulation support with minute-level response and several hours of continuous operation. The energy storage system of this embodiment possesses comprehensive advantages such as low construction and operation and maintenance costs, high operational safety, no special geological site selection requirements, rapid dynamic response, environmentally friendly throughout its entire life cycle, and the ability to provide rotational inertia to the power grid. It can provide an economically feasible technical path for the stable operation of high-proportion renewable energy power systems.

[0044] Example 2 This embodiment provides an energy storage method based on the energy storage system 100 combining heat pump and steam energy storage in Embodiment 1, including the following steps: When the system is in energy storage mode, the renewable energy power generation system 26 supplies power to the electrical components of the heat pump subsystem, and the heat pump subsystem generates steam; the steam heat energy generated by the heat pump subsystem is stored through the steam energy storage subsystem.

[0045] When the system is in energy release mode, the steam storage subsystem releases saturated steam, which then enters the power generation system and drives the power generation system to generate electricity.

[0046] In some implementations, in energy storage mode, the surplus power from wind and solar power drives all compressors to operate in coordination, converting the input electrical energy into saturated steam at 380 ℃ / 3.0 MPa and storing it in the steam accumulator 10; in energy release mode, the second isolation valve 14 and the second regulating valve 15 are opened, and the saturated water in the steam accumulator 10 can flash evaporate into steam within the range of 0.5 MPa-1.2 MPa to directly drive the steam turbine 11, with a response time of ≤2 minutes.

[0047] In some implementations, the energy storage method includes: S1. During periods of surplus wind and solar power generation, the heat pump subsystem is activated to utilize the abandoned electricity to gradually increase the heat from the medium and low temperature heat source, generating high-temperature and high-pressure steam that is then injected into the steam storage unit. S2. Monitor power grid peak-shaving demand signals; S3. When it is necessary to provide regulating power, open the second isolation valve 14 and the second regulating valve 15 to control the outlet steam pressure of the steam accumulator 10 and drive the saturated steam turbine 11 to generate electricity; S4. The exhaust steam is condensed by condenser 24 and then returned to water storage tank 8 to complete the working fluid cycle; In step S3, the energy release power is continuously adjusted on a minute-by-minute basis by adjusting the opening of the second regulating valve 15.

[0048] The control system can automatically start and stop the first isolation valve 17, the third isolation valve 18, and the fourth isolation valve 20 based on the grid peak-shaving demand signal, thereby achieving automatic switching between energy storage and energy release modes. A pressure detection device monitors the pressure inside the steam accumulator 10, connecting the control system to the electric shut-off valve and the pressure detection device. The control system can dynamically adjust the opening of the first regulating valve 16 based on the real-time pressure inside the steam accumulator 10 to regulate the steam flow and ensure system operational stability.

[0049] In some implementations, the second isolation valve 14 is closed in an emergency to instantly cut off the steam supply and protect the unit.

[0050] In some implementations, the energy storage system 100 combining a heat pump and steam energy storage operates in the following modes: Energy storage mode: Excess electricity from the renewable energy power generation system 26 drives the first compressor 4, the second compressor 5, and the steam compressor 9. The first regulating valve 16, the first isolation valve 17, the fourth isolation valve 20, and the fourth regulating valve 21 are opened; the second isolation valve 14, the second regulating valve 15, the third isolation valve 18, and the third regulating valve 19 are closed. Ambient air enters from the hot-side inlet (first channel inlet) of the evaporator 1 and exits from the hot-side outlet (first channel outlet) of the evaporator 1. The lower-stage heat pump refrigerant enters from the cold-side inlet (second channel inlet) of the evaporator 1, absorbs heat from the air, and exits from the cold-side outlet (second channel outlet) of the evaporator 1, then enters the first compressor 4 to increase its pressure. The lower-stage heat pump refrigerant discharged from the first compressor 4 enters the hot-side inlet (third channel inlet) of the intermediate heat exchanger 2, releases heat, and exits from the hot-side outlet (third channel outlet) of the intermediate heat exchanger 2, then enters the first expansion valve 6 for expansion. The low-pressure refrigerant discharged from the first expansion valve 6 re-enters the cold-side inlet of the evaporator 1 to absorb heat from the air and vaporize. The upper-stage heat pump working fluid enters through the cold-side inlet (fourth channel inlet) of the intermediate heat exchanger 2, absorbs heat, and exits through the cold-side outlet (fourth channel outlet) of the intermediate heat exchanger 2. It then enters the second compressor 5 to increase its pressure. The working fluid discharged from the second compressor 5 enters the hot-side inlet (fifth channel inlet) of the condenser 3, releases heat, and exits through the hot-side outlet (fifth channel outlet) of the condenser 3, entering the second expansion valve 7 for expansion. The low-pressure working fluid discharged from the second expansion valve 7 re-enters the intermediate heat exchanger 2 through the cold-side inlet to absorb heat from the lower-stage heat pump working fluid and vaporize. Water from the storage tank 8 is pumped by the feed water pump 22 through the fourth isolation valve 20 and the fourth regulating valve 21 to the cold-side inlet of the condenser 3. The feed water flow is regulated by the fourth regulating valve 21. The water entering the condenser 3 absorbs heat from the upper-stage heat pump working fluid and exits through the cold-side outlet of the condenser 3, entering the steam compressor 9 to increase its pressure. The steam discharged from the steam compressor 9 flows through the first isolation valve 17 and then enters the first regulating valve 16 to regulate the steam volume. After that, it is injected into the steam accumulator 10 tank, where it comes into direct contact with the saturated water inside and condenses, releasing latent heat to cause the water temperature and system pressure to rise synchronously, thus completing the storage of thermal energy.

[0051] Energy release mode: Open the second isolation valve 14, the second regulating valve 15, the third isolation valve 18, and the third regulating valve 19; close the first regulating valve 16, the first isolation valve 17, the fourth isolation valve 20, and the fourth regulating valve 21. High-pressure saturated water in the steam accumulator 10 flashes due to pressure reduction, generating saturated steam. This steam then flows through the second isolation valve 14, and the second regulating valve 15 controls the steam flow and pressure before entering the turbine 11 to expand and perform work. The exhaust steam after performing work is discharged into the condenser 24 and condensed into condensate, which is then pumped back to the water storage tank 8 by the condensate pump 23, completing the closed-loop circulation of the working fluid.

[0052] During the charging phase, the energy storage system utilizes abandoned wind and solar power to drive the compressor and increase the working fluid pressure and temperature. During the discharge and energy release phase, it controls the flash steam pressure and flow rate by adjusting the opening of the regulating valve, thereby achieving a minute-level grid power regulation response.

[0053] During peak electricity demand, the steam accumulator 10 releases saturated steam into the steam turbine 11 to generate electricity.

[0054] Water replenishment mode: Open the water replenishment valve 12 to replenish the steam accumulator 10 with water that meets the requirements. When sewage needs to be discharged, open the sewage discharge valve 13 to discharge the sewage in the tank.

[0055] In some implementations, the third isolation valve 18 can be used for maintenance isolation.

[0056] This invention, based on traditional electric-thermal energy storage systems, constructs an integrated architecture of multi-stage heat pump heating, steam compressor 9 pressurization, steam energy storage, and saturated steam power generation. This architecture can mitigate wind and solar power fluctuations and participate in grid peak shaving and frequency regulation. Under normal operating conditions, the system prioritizes utilizing off-peak electricity or wind and solar power curtailment to drive the multi-stage heat pump and steam compressor 9, progressively raising medium- and low-temperature thermal energy to a high-temperature, high-pressure saturated state. The thermal energy from the low-temperature heat source is synergistically converted into high-temperature, high-pressure steam with the input green electricity and stored in the steam accumulator 10. This efficiently converts wind and solar power curtailment and low-grade environmental heat into high-grade steam thermal energy. Compared to direct electric heating or single-stage heat pump subsystems, this significantly reduces irreversible thermodynamic losses and improves the electric-thermal conversion efficiency. When facing grid peak shaving demands, a second regulating valve 15 is used to control the steam outlet pressure, directly driving the steam turbine 11 to generate electricity, shortening the system response time and enabling rapid response to grid dispatch requirements. The energy storage system of this invention features low construction cost, high operational safety, environmental friendliness, fast response speed, and is simple and reliable, unrestricted by geographical conditions, thus helping to alleviate the phenomenon of "wind and solar curtailment." It can be widely applied to various high-proportion renewable energy bases, integrated energy systems in industrial parks, and integrated source-grid-load-storage projects, especially suitable for large-scale wind and solar bases in desert, Gobi, and arid regions with abundant land resources, urgent peak-shaving needs, and medium- and low-temperature waste heat conditions, demonstrating significant engineering applicability and promotional value.

[0057] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An energy storage system combining heat pump and steam energy storage, characterized in that: include: A heat pump subsystem, which is electrically connected to a renewable energy power generation system and is capable of generating steam; A steam energy storage subsystem, which is used to connect to the heat pump subsystem and store the steam thermal energy generated by the heat pump subsystem; The system includes a power generation system that can be connected to the steam energy storage subsystem. The steam energy storage subsystem can release saturated steam, which can enter the power generation system and drive it to generate electricity.

2. The energy storage system combining heat pump and steam energy storage according to claim 1, characterized in that: It also includes a first isolation valve and a second isolation valve. The first isolation valve is used to be installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; the second isolation valve is used to be installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the power generation system.

3. The energy storage system combining heat pump and steam energy storage according to claim 1, characterized in that: It also includes a first regulating valve and a second regulating valve. The first regulating valve is used to be installed on the pipeline between the steam outlet of the heat pump subsystem and the steam inlet of the steam energy storage subsystem; the second regulating valve is used to be installed on the pipeline between the steam outlet of the steam energy storage subsystem and the steam inlet of the power generation system.

4. The energy storage system combining heat pump and steam energy storage according to claim 1, characterized in that: It also includes a water storage tank, a condenser, a condensate pump, and a feedwater pump. The inlet and outlet of the water storage tank are connected to the outlet of the condensate pump and the inlet of the feedwater pump, respectively. The outlet of the feedwater pump is connected to the heat pump subsystem and can transport the water working medium in the water storage tank to the heat pump subsystem. When the water working medium flows through the heat pump subsystem, it can absorb heat and vaporize into steam. The condenser is used to connect to the power generation system. The exhaust steam generated by the power generation system after generating electricity under the action of the saturated steam can enter the condenser and be condensed into condensate by the condenser. The condensate pump is used to connect to the condenser and can transport the condensate in the condenser to the water storage tank.

5. The energy storage system combining heat pump and steam energy storage according to claim 4, characterized in that: It also includes a third isolation valve and a fourth isolation valve. The third isolation valve is used to install on the pipeline between the outlet of the condenser and the inlet of the water storage tank; the fourth isolation valve is used to install on the pipeline between the outlet of the water storage tank and the water inlet of the heat pump subsystem.

6. The energy storage system combining heat pump and steam energy storage according to claim 4, characterized in that: It also includes a third regulating valve and a fourth regulating valve. The third regulating valve is used to install on the pipeline between the outlet of the condenser and the inlet of the water storage tank; the fourth regulating valve is used to install on the pipeline between the outlet of the water storage tank and the water inlet of the heat pump subsystem.

7. The energy storage system combining heat pump and steam energy storage according to claim 4, characterized in that: The heat pump subsystem is a multi-stage heat pump subsystem.

8. The energy storage system combining heat pump and steam energy storage according to claim 7, characterized in that: The heat pump subsystem includes an evaporator, an intermediate heat exchanger, a condenser, a first compressor, a second compressor, a first expansion valve, a second expansion valve, and a steam compressor. The first compressor, the second compressor, and the steam compressor are all electrically connected to the renewable energy power generation system. The evaporator has a first heat exchange channel and a second heat exchange channel; the intermediate heat exchanger has a third heat exchange channel and a fourth heat exchange channel; and the condenser has a fifth heat exchange channel and a sixth heat exchange channel. The outlet of the second heat exchange channel, the inlet of the first compressor, the outlet of the first compressor, the inlet of the third heat exchange channel, the outlet of the third heat exchange channel, the inlet of the first expansion valve, the outlet of the first expansion valve, and the inlet of the second heat exchange channel are sequentially connected to form a first circulation channel. The outlet of the fourth heat exchange channel and the inlet of the second compressor... The outlet of the second compressor, the inlet of the fifth heat exchange channel, the outlet of the fifth heat exchange channel, the inlet of the second expansion valve, the outlet of the second expansion valve, and the inlet of the fourth heat exchange channel are sequentially connected to form a second circulation channel; the outlet of the water storage tank, the inlet of the sixth heat exchange channel, the outlet of the sixth heat exchange channel, and the steam inlet of the steam energy storage subsystem are sequentially connected; the first heat exchange channel is used to introduce ambient air; the lower-stage heat pump working fluid flowing through the second heat exchange channel can absorb the heat of the ambient air; the lower-stage heat pump working fluid flowing through the third heat exchange channel heats the upper-stage heat pump working fluid flowing through the fourth heat exchange channel; the upper-stage heat pump working fluid flowing through the fifth heat exchange channel can heat the water working fluid flowing through the sixth heat exchange channel and vaporize the water working fluid into steam.

9. The energy storage system combining heat pump and steam energy storage according to claim 4, characterized in that: The steam energy storage subsystem includes a steam accumulator, a water supply valve, and a drain valve. The steam inlet of the steam accumulator is connected to the steam outlet of the heat pump subsystem, and the steam outlet of the steam accumulator is connected to the steam inlet of the power generation system. The water supply valve is installed at the water inlet end of the steam accumulator, and the drain valve is installed at the water outlet end of the steam accumulator. The power generation system includes a steam turbine and a generator. The steam inlet of the steam turbine is connected to the steam outlet of the steam storage subsystem. The output end of the steam turbine is connected to the input end of the generator. The exhaust steam outlet of the steam turbine is connected to the exhaust steam inlet of the condenser.

10. An energy storage method based on an energy storage system combining a heat pump and steam energy storage as described in any one of claims 1 to 9, characterized in that: Includes the following steps: When the system is in energy storage mode, the renewable energy power generation system supplies power to the electrical components of the heat pump subsystem, and the heat pump subsystem generates steam; the steam energy storage subsystem stores the steam heat energy generated by the heat pump subsystem. When the system is in energy release mode, the steam energy storage subsystem releases saturated steam, which then enters the power generation system and drives the power generation system to generate electricity.

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