A heat and power cogeneration system and method with light and heat storage complementation

Abstract

This invention discloses a combined heat and power (CHP) system and method that integrates photovoltaic (PV) energy storage and thermal energy storage, comprising a compressed air energy storage unit, a photovoltaic (PV) unit, a molten salt energy storage unit, and a collaborative control unit. The compressed air energy storage unit includes a motor, a compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, an expander, a generator, and a gas storage tank. The PV unit includes photovoltaic panels and an inverter. The molten salt energy storage unit includes a high-temperature molten salt tank, a high-temperature molten salt pump, a fourth heat exchanger, a low-temperature molten salt tank, a low-temperature molten salt pump, and a deaerator. The collaborative control unit connects to an external power source and the motor; it also connects to the motor and the high-temperature molten salt tank, and connects to the electrical load and the thermal load. This invention effectively overcomes the intermittent nature of PV power generation through deep collaborative operation of compressed air energy storage, PV power generation, and molten salt energy storage, significantly reducing the curtailment rate. Furthermore, through a photovoltaic-thermal complementary scheduling mechanism, it ensures high stability of power and heat output, greatly improving the overall reliability of energy supply.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a combined heat and power system and method that integrates photovoltaic and thermal energy storage. Background Technology

[0002] With the large-scale grid connection of renewable energy (especially photovoltaic power generation), the inherent intermittency and volatility pose a severe challenge to the stable operation of the power grid. Energy storage technology, as a key means to smooth out fluctuations and ensure grid security, has attracted much attention. However, existing mainstream energy storage technologies each have their limitations: Compressed air energy storage (CAES), while possessing advantages such as large storage capacity and long lifespan, faces technical bottlenecks such as low energy conversion efficiency and insufficient heat replenishment during the energy release process. Furthermore, existing systems struggle to continuously provide high-quality thermal energy, and combined heat and power (CHP) lacks flexibility, making it difficult to dynamically and collaboratively respond to electricity / heat load demands. Solar photovoltaic (PV), as an abundant and clean renewable energy source, offers significant energy conservation, emission reduction, environmental, and social benefits, but its unstable output power and limited grid acceptance capacity lead to frequent "curtailment" phenomena, making it difficult to guarantee a continuous and stable power supply. Molten salt thermal energy storage (TES), on the other hand, excels in strong thermal storage capacity and good thermal stability, but its economic viability is highly dependent on combined heat and power or pure heating scenarios, limiting its application scope.

[0003] Therefore, there is an urgent need to develop a system and method that can organically integrate the advantages of compressed air energy storage, photovoltaic power generation and molten salt thermal energy storage, and achieve efficient synergistic operation, so as to comprehensively improve energy storage efficiency and system reliability, effectively solve the problem of photovoltaic curtailment, and enhance the dynamic response capability to diversified energy demands. Summary of the Invention

[0004] In view of the above-mentioned shortcomings and defects of the prior art, the purpose of this invention is to provide a combined heat and power system and method that integrates photovoltaic energy storage and thermal energy, and to solve the problem that there is no system in the prior art that can organically integrate the advantages of compressed air energy storage, photovoltaic power generation and molten salt thermal energy storage.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a photovoltaic-storage-thermal complementary cogeneration system, comprising a compressed air energy storage unit, a photovoltaic unit, a molten salt energy storage unit, and a collaborative control unit.

[0006] The compressed air energy storage unit includes an electric motor, a compressor, a first heat exchanger, a second heat exchanger, a third heat exchanger, an expander, and a generator connected in sequence.

[0007] It also includes a gas storage facility, which is connected between the second and third heat exchangers via a bypass.

[0008] The photovoltaic unit includes a photovoltaic panel and an inverter connected in sequence.

[0009] The molten salt energy storage unit includes a high-temperature molten salt tank, a high-temperature molten salt pump, a fourth heat exchanger, a low-temperature molten salt tank, a low-temperature molten salt pump, and a deaerator, all connected together.

[0010] The aforementioned collaborative control unit is connected to an external power source and a motor.

[0011] The aforementioned collaborative control unit is also connected to the electric motor and the high-temperature molten salt tank, respectively, for sending the electrical energy generated by the photovoltaic unit to the electric motor, the high-temperature molten salt tank, or directly outputting it.

[0012] Furthermore, the co-control unit connects to the electrical load and thermal load, and can provide feedback on the electrical load and thermal load requirements.

[0013] The present invention also has the following technical features:

[0014] The molten salt outlet of the high-temperature molten salt tank is connected to the first inlet of the fourth heat exchanger, the first outlet of the fourth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the molten salt outlet of the low-temperature molten salt tank is connected to the first inlet of the first heat exchanger, and the first outlet of the first heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank.

[0015] The molten salt outlet of the high-temperature molten salt tank is also connected to the first inlet of the third heat exchanger, and the first outlet of the third heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank.

[0016] The second inlet of the fourth heat exchanger is also connected to the outlet of the deaerator, the inlet of the deaerator is connected to the first outlet of the second heat exchanger, the first outlet of the second heat exchanger is connected to the inlet of the deaerator, and the first inlet of the second heat exchanger is connected to demineralized water.

[0017] A high-temperature molten salt pump and a first control valve are installed on the pipeline between the molten salt outlet of the high-temperature molten salt tank and the first inlet of the fourth heat exchanger.

[0018] A second control valve is installed on the first inlet pipe of the third heat exchanger.

[0019] A third control valve is installed on the pipeline between the first outlet of the fourth heat exchanger and the molten salt inlet of the cryogenic molten salt tank.

[0020] A cryogenic molten salt pump is installed on the pipeline between the molten salt outlet of the cryogenic molten salt tank and the first inlet of the first heat exchanger.

[0021] The high-temperature molten salt tank is equipped with an electric heating device, and the photovoltaic unit and the molten salt energy storage unit are connected to the electric heating device via a co-controller.

[0022] The air outlet of the compressor is connected to the second inlet of the first heat exchanger, the second outlet of the first heat exchanger is connected to the second inlet of the second heat exchanger, the second outlet of the second heat exchanger is connected to the second inlet of the third heat exchanger, the second outlet of the third heat exchanger is connected to the air inlet of the expander, and the air outlet of the expander is connected to the air inlet of the compressor.

[0023] The second outlet of the second heat exchanger is also connected to a gas storage tank, and the gas storage tank is also connected to the second inlet of the third heat exchanger.

[0024] A fourth control valve is installed on the pipeline between the second outlet of the second heat exchanger and the second inlet of the third heat exchanger.

[0025] A fifth control valve is installed on the pipeline between the second outlet of the second heat exchanger and the gas storage tank, and a sixth control valve is installed on the pipeline between the gas storage tank and the second inlet of the third heat exchanger.

[0026] A seventh control valve is installed on the pipeline between the air outlet of the expander and the air inlet of the compressor.

[0027] The present invention also provides a photoelectric storage and thermal complementary cogeneration method, which is implemented using the above-mentioned photoelectric storage and thermal complementary cogeneration system.

[0028] Compared with the prior art, the beneficial technical effects of this invention are: (I) The photoelectric storage and thermal complementary cogeneration system of the present invention effectively overcomes the intermittent challenge of photovoltaic power generation by deeply coordinating the operation of compressed air energy storage, photovoltaic power generation and molten salt energy storage, significantly reduces the curtailment rate (which can be controlled below 5%), and ensures the high stability of power and heat output through the photoelectric thermal complementary scheduling mechanism, thereby greatly improving the reliability of the overall energy supply.

[0029] (II) The photovoltaic-storage-thermal complementary cogeneration system of the present invention effectively improves the operating temperature of the molten salt energy storage unit by coupling the photovoltaic unit, and significantly improves the power generation efficiency of the compressed air energy storage unit. The system achieves a compressed air energy storage electro-electric conversion efficiency of 75-82%, which is 15-22% higher than that of a single compressed air energy storage system.

[0030] (III) The solar-storage-thermal complementary cogeneration system of the present invention can simultaneously and efficiently meet the user's demand for electricity and high-quality heat (industrial steam or high-temperature hot water), significantly improving the utilization value of energy and reducing waste. The unique "electricity-heat-storage" coordinated operation mode, combined with intelligent coordination control strategy, further optimizes the energy utilization efficiency of the entire system.

[0031] (IV) The solar-storage-thermal complementary cogeneration system of the present invention, through a core collaborative control unit, achieves complementary advantages of multiple energy technologies and optimized energy flow allocation and operation mode switching. This not only significantly improves the overall performance and operating efficiency of the energy storage system, but also enables the system's comprehensive energy utilization rate to exceed 85%, representing a 30%-40% increase in efficiency compared to a single-energy system. Simultaneously, through data-driven decision-making and multi-energy collaboration, it achieves the goals of "demand priority, complementary energy storage, and optimal efficiency."

[0032] (V) The method of this invention solves the problems of improving the power generation efficiency of compressed air energy storage units and the unique "electricity-heat-storage" coordinated operation mode, meeting diverse needs and synergistic efficiency. By predicting user electric and heat loads and photovoltaic output, and taking into account peak and off-peak electricity periods for coordinated control of compressed air energy storage and molten salt energy storage systems, it has the advantage of advance regulation.

[0033] Based on heat supply Q 供应 -Q 需求 ≤0 (or power supply P) 供应 -P 需求 The control strategy of ≤0 can make the solar-storage-thermal complementary cogeneration system and method provided by the present invention have a better energy-saving effect. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the combined heat and power system with photovoltaic and thermal energy storage that is complementary to the solar energy storage system of this application.

[0035] Figure 2 yes Figure 1 Enlarged view of a part Figure I .

[0036] Figure 3 yes Figure 1 Enlarged view of a part Figure II .

[0037] The meanings of the labels in the attached diagram are as follows: A - Electrical load, B - Thermal load, C - Solar energy, D - Off-peak electricity, E - Demineralized water, F - Air.

[0038] 1-Compressed air energy storage unit, 2-Photovoltaic unit, 3-Molten salt energy storage unit, 4-Cooperative control unit, 5-First control valve, 6-Second control valve, 7-Third control valve, 8-Fourth control valve, 9-Fifth control valve, 10-Sixth control valve, 11-Seventh control valve.

[0039] 1-1-Electric motor, 1-2-Compressor, 1-3-First heat exchanger, 1-4-Second heat exchanger, 1-5-Third heat exchanger, 1-6-Expander, 1-7-Generator, 1-8-Gas storage tank.

[0040] 2-1- Photovoltaic panel, 2-2- Inverter.

[0041] 3-1-High temperature molten salt tank, 3-2-High temperature molten salt pump, 3-3-Fourth heat exchanger, 3-4-Low temperature molten salt tank, 3-5-Low temperature molten salt pump, 3-6-Deaerator.

[0042] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the prior art.

[0044] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0045] Example 1: A solar-storage-thermal complementary cogeneration system, such as Figures 1-3 As shown, it includes a compressed air energy storage unit 1, a photovoltaic unit 2, a molten salt energy storage unit 3, and a collaborative control unit 4.

[0046] The compressed air energy storage unit 1 includes an electric motor 1-1, a compressor 1-2, a first heat exchanger 1-3, a second heat exchanger 1-4, a third heat exchanger 1-5, an expander 1-6, and a generator 1-7 connected in sequence.

[0047] It also includes gas storage tanks 1-8, which are connected between the second heat exchanger 1-4 and the third heat exchanger 1-5 via a bypass.

[0048] The photovoltaic unit 2 includes a photovoltaic panel 2-1 and an inverter 2-2 connected in sequence.

[0049] The molten salt energy storage unit 3 includes a high-temperature molten salt tank 3-1, a high-temperature molten salt pump 3-2, a fourth heat exchanger 3-3, a low-temperature molten salt tank 3-4, a low-temperature molten salt pump 3-5, and a deaerator 3-6 connected together.

[0050] The collaborative control unit 4 is connected to an external power source and a motor 1-1.

[0051] The collaborative control unit 4 is also connected to the motor 1-1 and the high-temperature molten salt tank 3-1, respectively, for sending the electrical energy generated by the photovoltaic unit 2 to the motor 1-1, the high-temperature molten salt tank 3-1 or directly outputting it.

[0052] Furthermore, the co-control unit 4 is connected to the electrical load A and the thermal load B, and can provide feedback on the electrical and thermal load requirements.

[0053] The air compression adopts multi-stage isothermal compression and interstage cooling technology. The heat of compression generated by the compressed air is transferred to the molten salt energy storage unit through the first heat exchanger 1-3 and the second heat exchanger 1-4. The compressed air energy storage unit adopts a high-pressure gas storage tank 1-8, which stores compressed air at a pressure ≥10MPa. During the energy release stage, the low-temperature high-pressure air in the gas storage tank 1-8 is heated into high-temperature high-pressure compressed air through the third heat exchanger 1-5 and enters the expander 1-6 to do work and drive the generator 1-7 to generate electricity.

[0054] Photovoltaic unit 2 is responsible for converting solar energy into electrical energy. The photovoltaic unit converts DC power into AC power through inverter 2-2. The output power is given priority to user loads, and the surplus power is provided to molten salt energy storage unit 3 and compressed air energy storage unit 1.

[0055] During the energy storage phase, the high-temperature compression heat generated by the compressed air energy storage unit is stored in the high-temperature molten salt tank 3-1 through the first heat exchanger 1-3 (the temperature of this process is set to ~300℃). The low-temperature compression heat generated heats the demineralized water through the second heat exchanger 1-4, and then through the deaerator 3-6 and the fourth heat exchanger 3-3 to produce heat energy to the outside. This heat energy is industrial steam.

[0056] Meanwhile, the surplus electricity of photovoltaic unit 2 is stored as heat in high-temperature molten salt tank 3-1 through an electric heating device (the temperature of this process is set to ~500℃). According to the instructions of the coordinating control unit 4, the high-temperature molten salt tank 3-1 opens the first control valve 5 and releases heat through the fourth heat exchanger 3-3 to the demineralized water to produce heat energy.

[0057] During the energy release phase, the high-temperature molten salt is transported to the third heat exchanger 1-5 via the high-temperature molten salt pump 3-2 to heat the low-temperature high-pressure compressed air into high-temperature high-pressure compressed air. The released low-temperature molten salt is then stored in the low-temperature molten salt tank 3-1.

[0058] The collaborative control unit 4 includes a mode selection module, a data acquisition module, a prediction module, a decision-making module, an execution module, a security monitoring module, and a judgment module.

[0059] The collaborative control unit is used to monitor user demand and energy supply in real time, and automatically adjust the operating status of each unit according to demand.

[0060] The mode selection module is used to select between heat-driven power supply or power-driven heat supply operation modes.

[0061] The data acquisition module collects data in real time, such as the supply of electrical load and heat load, and the status of various devices in the energy storage system, through sensors.

[0062] The forecasting module predicts the demand and supply of thermal power loads for a future period based on historical and real-time data.

[0063] The decision-making module formulates a coordinated operation strategy for compressed air energy storage, photovoltaic and molten salt energy storage based on the coupling of the current peak and valley periods of heat supply Q supply - Q demand ≤ 0 (or power supply P supply - P demand ≤ 0).

[0064] The execution module outputs control commands to each unit according to the operation strategy, so as to realize the intelligent coordinated operation of the energy storage system.

[0065] The safety monitoring module monitors the system's operating status in real time and stores real-time data, control commands, and fault records in the database.

[0066] The judgment module makes judgments based on real-time monitoring data from the security monitoring module to ensure the system continues to run in a loop.

[0067] This application discloses a photovoltaic-thermal energy storage combined heat and power system and method. The compressed air energy storage unit 1, molten salt energy storage unit 3, and photovoltaic unit 2 operate collaboratively according to real-time energy supply and demand. A collaborative control unit 4 enables optimized energy allocation and efficient utilization, providing efficient electrical and thermal energy to external systems. As a preferred embodiment: The molten salt outlet of the high-temperature molten salt tank 3-1 is connected to the first inlet of the fourth heat exchanger 3-3, the first outlet of the fourth heat exchanger 3-3 is connected to the molten salt inlet of the low-temperature molten salt tank 3-4, the molten salt outlet of the low-temperature molten salt tank 3-4 is connected to the first inlet of the first heat exchanger 1-3, and the first outlet of the first heat exchanger 1-3 is connected to the molten salt inlet of the high-temperature molten salt tank 3-1.

[0068] The molten salt outlet of the high-temperature molten salt tank 3-1 is also connected to the first inlet of the third heat exchanger 1-5, and the first outlet of the third heat exchanger 1-5 is connected to the molten salt inlet of the low-temperature molten salt tank 3-4.

[0069] The second inlet of the fourth heat exchanger 3-3 is also connected to the outlet of the deaerator 3-6. The inlet of the deaerator 3-6 is connected to the first outlet of the second heat exchanger 1-4. The first outlet of the second heat exchanger 1-4 is connected to the inlet of the deaerator 3-6. The first inlet of the second heat exchanger 1-4 is connected to the demineralized water E.

[0070] As a preferred embodiment: A high-temperature molten salt pump 3-2 and a first control valve 5 are installed on the pipeline between the molten salt outlet of the high-temperature molten salt tank 3-1 and the first inlet of the fourth heat exchanger 3-3.

[0071] A second control valve 6 is installed on the first inlet pipe of the third heat exchanger 1-5.

[0072] A third control valve 7 is installed on the pipeline between the first outlet of the fourth heat exchanger 3-3 and the molten salt inlet of the cryogenic molten salt tank 3-4.

[0073] A cryogenic molten salt pump 3-5 is installed on the pipeline between the molten salt outlet of the cryogenic molten salt tank 3-4 and the first inlet of the first heat exchanger 1-3.

[0074] The high-temperature molten salt tank 3-1 is equipped with an electric heating device 3-7, and the photovoltaic unit and molten salt energy storage unit co-controller 4-2 are connected to the electric heating device 3-7.

[0075] As a preferred embodiment: The air outlet of the compressor 1-2 is connected to the second inlet of the first heat exchanger 1-3, the second outlet of the first heat exchanger 1-3 is connected to the second inlet of the second heat exchanger 1-4, the second outlet of the second heat exchanger 1-4 is connected to the second inlet of the third heat exchanger 1-5, the second outlet of the third heat exchanger 1-5 is connected to the air inlet of the expander 1-6, and the air outlet of the expander 1-6 is connected to the air inlet of the compressor 1-2.

[0076] The second outlet of the second heat exchanger 1-4 is also connected to the gas storage tank 1-8, and the gas storage tank 1-8 is also connected to the second inlet of the third heat exchanger 1-5.

[0077] As a preferred embodiment: A fourth control valve 8 is installed on the pipeline between the second outlet of the second heat exchanger 1-4 and the second inlet of the third heat exchanger 1-5.

[0078] A fifth control valve 9 is installed on the pipeline between the second outlet of the second heat exchanger 1-4 and the gas storage tank 1-8, and a sixth control valve 10 is installed on the pipeline between the gas storage tank 1-8 and the second inlet of the third heat exchanger 1-5.

[0079] Example 2: A photoelectric-storage-thermal complementary cogeneration method is implemented using the photoelectric-storage-thermal complementary cogeneration system as described in Example 1.

[0080] When providing combined heat and power (CHP) with electricity as the main component, during the energy storage phase, when there is sufficient sunlight, the photovoltaic unit 2 prioritizes outputting electrical energy to the outside based on the demand for electrical load (A) and thermal load (B) fed back by the collaborative control unit 4.

[0081] When there is a surplus of electrical energy, the DC power is converted into AC power by the inverter 2-2 to supplement the molten salt energy storage unit 3 for energy storage.

[0082] Furthermore, when the high-temperature molten salt tank 3-1 of the molten salt energy storage unit 3 reaches the set temperature, the surplus electrical energy can be replenished to the compressed air energy storage unit 1. The compressed air energy storage unit 1 uses the surplus photovoltaic electrical energy to drive the motor 1-1 to drive the compressor 1-2 to compress the air and store it in the air storage tank 1-8. During this process, the second control valve 6 is opened, and the seventh control valve 11 and the first control valve 5 are closed.

[0083] The heat generated during compression is transferred to the molten salt energy storage unit 3 through the first heat exchanger 1-3 and the second heat exchanger 1-4.

[0084] When there is insufficient sunlight, the compressed air energy storage unit 1 uses off-peak electricity to drive the motor 1-1 to drive the compressor 1-2 to compress air and store it in the air storage tank 1-8. The heat generated during the compression process is transferred to the molten salt energy storage unit 3 for storage through the first heat exchanger 1-3 and the second heat exchanger 1-4.

[0085] During the energy release phase, the system releases compressed air energy from compressed air storage unit 1 and high thermal energy from molten salt storage unit 3, efficiently outputting electrical energy. In compressed air storage unit 1, the high-pressure air from storage tank 1-8 is heated by the third heat exchanger 1-5. During this process, the second control valve 6 opens, allowing the air to enter the expander 1-6 to drive the generator 1-7 and generate electricity. The heat in the third heat exchanger 1-5 comes from the molten salt storage unit 3. Simultaneously, the molten salt storage unit 3 releases heat through the fourth heat exchanger 3-3 to heat the demineralized water. During this process, the second control valve 6 and the first control valve 5 open, producing thermal energy (industrial steam or high-temperature hot water).

[0086] When the system provides cogeneration with heat energy as the main source, under sufficient sunlight, photovoltaic unit 2 prioritizes supplementing the molten salt energy storage unit 3 with electrical energy based on the demand of electrical load A and heat load B fed back by the collaborative control unit 4. When sunlight is insufficient, compressed air energy storage unit 1 uses off-peak electricity to compress air and generate compressed heat, which is stored in molten salt energy storage unit 3 through the first heat exchanger 1-3 and the second heat exchanger 1-4. Molten salt energy storage unit 3 releases heat to the outside through the fourth heat exchanger 3-3 as needed, transferring it to the demineralized water and producing heat energy (industrial steam or high-temperature hot water).

[0087] When there is a high demand for heat load, the compressed air energy storage unit 1 closes the fifth control valve 9 and the sixth control valve 10 and opens the fourth control valve 8, so that the high-pressure low-temperature compressed air after passing through the second heat exchanger 1-4 does not enter or enters the air storage tank 1-8 in a small amount. Then, by closing the second control valve 6, the heat from the high-temperature molten salt pump 3-2 does not enter the third heat exchanger 1-5. The high-pressure low-temperature compressed air passes through the third heat exchanger 1-5 without being heated and directly enters the expander 1-6 to do work and drive the generator 1-7 to generate a small amount of electricity. The discharged air is led back to the compressor 1-2 for circulation through the opened seventh control valve 11.

[0088] An operational strategy for a combined heat and power system and method that integrates solar energy and thermal energy storage, operating under the "heat-driven power generation" mode.

[0089] First, the user-side thermal and power load and current data of each system and equipment are collected. Then, based on historical data, the solar-storage combined heat and power system predicts the user demand load and determines ΔQ=Q. 供应 -Q 需求 Check if the value ≤0 is less than or equal to zero, and also determine the current power period.

[0090] When ΔQ is less than or equal to zero: a. Peak electricity hours: The electricity from photovoltaic unit 2 is given priority to the grid. The surplus electricity from photovoltaic unit 2 heats the molten salt. At the same time, all the energy from expanders 1-6 is released and discharged. Meanwhile, the molten salt energy storage unit 3 releases heat to the first heat exchanger 1-3 to provide heat energy to the outside.

[0091] b. During off-peak hours: Off-peak electricity drives the compressor to store energy, and the waste heat from the compression heats the molten salt unit to store heat. At the same time, all the photovoltaic power heats the molten salt unit to store heat, and the molten salt unit releases heat to the first heat exchanger 1-3 to provide heat energy to the outside.

[0092] c. During normal power supply periods: Photovoltaic unit 3 prioritizes grid connection of electricity, and surplus photovoltaic unit 2 uses electricity to heat molten salt to store heat. The molten salt then provides heat to the outside through the first heat exchanger 1-3.

[0093] on the contrary: a. Peak electricity period: All the electricity generated by photovoltaic unit 2 is fed into the grid, while all the energy released by expanders 1-6 is discharged. Molten salt energy storage unit 3 outputs heat to expanders 1-6 to improve the efficiency of expanders. Molten salt provides a small amount of heat energy to the outside through the first heat exchanger 1-3.

[0094] b. During off-peak hours: The photovoltaic unit 2's electricity prioritizes driving the compressor's energy storage and simultaneously heats the molten salt to store heat; if the photovoltaic power is insufficient, the off-peak electricity D from the power grid is used, and the waste heat from the compressor 1-2 heats the second heat exchanger 1-4 to provide a small amount of heat energy to the outside.

[0095] c. During normal power supply periods: The electricity generated by photovoltaic unit 2 is given priority to the grid. The surplus electricity from photovoltaic unit 2 heats the molten salt to store heat. The molten salt then provides a small amount of heat to the outside through the first heat exchanger 1-3.

[0096] Furthermore, when ΔQ is less than or equal to zero, determine that ΔQ = Q. 供应 -Q 需求 ≤0 also determines the current power period: a. Peak and normal power periods: The photovoltaic unit 2 uses electricity to heat the molten salt first, while the molten salt energy storage unit 3 releases heat to the first heat exchanger 1-3, providing a large amount of heat energy to the outside.

[0097] b. During off-peak hours: Off-peak electricity D drives compressor 1-2, and the waste heat from compression directly heats molten salt energy storage unit 3 and the second heat exchanger 1-4. At the same time, all photovoltaic power heats molten salt energy storage unit 3 to store heat, and molten salt energy storage unit 3 releases heat to the first heat exchanger 1-3, providing a large amount of heat energy to the outside. Compressed air does not enter the gas storage 1-8 but directly drives expander 1-6 to generate a small amount of electricity.

[0098] Otherwise, it directly enters the execution module.

[0099] According to the operating strategy, the execution module outputs control commands to each unit, controlling compressors 1-2 (start / stop, power adjustment), expanders 1-6 (start / stop, discharge volume adjustment), and gas storage tanks 1-8 valve opening and closing; controlling electric heating (start / stop, power adjustment), controlling molten salt pump start / stop, controlling heat exchanger valve opening adjustment; controlling photovoltaic inverter start / stop; and controlling the grid-connected device output power.

[0100] The safety monitoring module monitors the compressor / expander operating status (current, voltage, temperature) and the upper limit of the gas storage pressure in real time; it also monitors the molten salt temperature and molten salt pump (current, voltage, temperature); whether the inverter is faulty; and the operating status of the heat exchanger (pressure, temperature). The module stores real-time data, control commands, and fault records in a database for subsequent analysis.

[0101] The judgment module makes a judgment based on the real-time monitoring data of the safety monitoring module. If the equipment fails, the protection mechanism is triggered and the operation ends; otherwise, the next cycle continues.

[0102] An operational strategy for a combined heat and power system and method that integrates solar energy and thermal energy storage, operating under the "electricity-driven heat" mode.

[0103] First, the user-side thermal and power load and current data of each system and equipment are collected. Then, based on historical data, the solar-storage combined heat and power system predicts the user demand load and determines ΔP=P. 供应 -P 需求 Check if the value ≤0 is less than or equal to zero, and also determine the current power period.

[0104] When ΔP is less than or equal to zero: During peak power periods: all the electricity generated by photovoltaic unit 2 is fed into the grid, while all the energy released by expanders 1-6 is discharged. Molten salt energy storage unit 3 outputs heat to expanders 1-6 to improve their efficiency. Molten salt provides a small amount of heat to the outside through the first heat exchanger 1-3.

[0105] b. During off-peak hours: The photovoltaic unit 2's electricity prioritizes driving the compressor's energy storage and simultaneously heats the molten salt to store heat; if the photovoltaic power is insufficient, the off-peak electricity D from the power grid is used, and the waste heat from the compressor 1-2 heats the second heat exchanger 1-4 to provide a small amount of heat energy to the outside.

[0106] c. During normal power supply periods: The photovoltaic unit 2 prioritizes grid connection for electricity, and the surplus heats the molten salt for storage. The molten salt then provides a small amount of heat to the outside through the first heat exchanger 1-3.

[0107] on the contrary: a. Peak electricity hours: The electricity from photovoltaic unit 2 is given priority to the grid. The surplus electricity from photovoltaic unit 2 heats the molten salt. At the same time, all the energy from expanders 1-6 is released and discharged. Meanwhile, the molten salt energy storage unit 3 releases heat to the first heat exchanger 1-3 to provide heat energy to the outside.

[0108] b. During off-peak hours: Off-peak electricity D drives the compressor to store energy, and the waste heat from the compression heats the molten salt energy storage unit 3 to store heat. At the same time, all the electricity from the photovoltaic unit 2 heats the molten salt energy storage unit 3 to store heat. The molten salt energy storage unit 3 releases heat to the first heat exchanger 1-3 to provide heat energy to the outside.

[0109] c. During normal power supply periods: The electricity generated by photovoltaic unit 2 is given priority to the grid. The surplus electricity from photovoltaic unit 2 heats the molten salt to store heat. The molten salt then provides heat to the outside through the first heat exchanger 1-3.

[0110] The subsequent execution module, security monitoring module, and judgment module are the same as those described above.

[0111] This invention innovatively proposes a judgment and control strategy based on the coupling of heat supply Q supply - Q demand ≤ 0 (or power supply P supply - P demand ≤ 0) with the current power period. This coordinated control strategy enables the solar-storage-thermal complementary cogeneration system and method provided by this invention to have a superior energy-saving effect.

[0112] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the scope of the technology disclosed in the present invention without creative effort are covered within the scope of protection of the present invention.

Claims

1. A combined heat and power system that integrates photovoltaic and thermal energy storage, characterized in that, It includes a compressed air energy storage unit (1), a photovoltaic unit (2), and a molten salt energy storage unit (3); The compressed air energy storage unit (1) includes an electric motor (1-1), a compressor (1-2), a first heat exchanger (1-3), a second heat exchanger (1-4), a third heat exchanger (1-5), an expander (1-6), and a generator (1-7) connected in sequence. It also includes a gas storage tank (1-8), which is connected between the second heat exchanger (1-4) and the third heat exchanger (1-5) via a bypass. The photovoltaic unit (2) includes a photovoltaic panel (2-1) and an inverter (2-2) connected in sequence. The molten salt energy storage unit (3) includes a high-temperature molten salt tank (3-1), a high-temperature molten salt pump (3-2), a fourth heat exchanger (3-3), a low-temperature molten salt tank (3-4), a low-temperature molten salt pump (3-5), and a deaerator (3-6) connected together.

2. The solar-storage-thermal complementary cogeneration system as described in claim 1, characterized in that, The molten salt outlet of the high-temperature molten salt tank (3-1) is connected to the first inlet of the fourth heat exchanger (3-3), the first outlet of the fourth heat exchanger (3-3) is connected to the molten salt inlet of the low-temperature molten salt tank (3-4), the molten salt outlet of the low-temperature molten salt tank (3-4) is connected to the first inlet of the first heat exchanger (1-3), and the first outlet of the first heat exchanger (1-3) is connected to the molten salt inlet of the high-temperature molten salt tank (3-1). The molten salt outlet of the high-temperature molten salt tank (3-1) is also connected to the first inlet of the third heat exchanger (1-5), and the first outlet of the third heat exchanger (1-5) is connected to the molten salt inlet of the low-temperature molten salt tank (3-4). The second inlet of the fourth heat exchanger (3-3) is also connected to the outlet of the deaerator (3-6). The inlet of the deaerator (3-6) is connected to the first outlet of the second heat exchanger (1-4). The first outlet of the second heat exchanger (1-4) is connected to the inlet of the deaerator (3-6). The first inlet of the second heat exchanger (1-4) is connected to the demineralized water.

3. The solar-storage-thermal complementary cogeneration system as described in claim 2, characterized in that, A high-temperature molten salt pump (3-2) and a first control valve (5) are installed on the pipeline between the molten salt outlet of the high-temperature molten salt tank (3-1) and the first inlet of the fourth heat exchanger (3-3). A second control valve (6) is installed on the first inlet pipe of the third heat exchanger (1-5); A third control valve (7) is installed on the pipeline between the first outlet of the fourth heat exchanger (3-3) and the molten salt inlet of the cryogenic molten salt tank (3-4); A cryogenic molten salt pump (3-5) is installed on the pipeline between the molten salt outlet of the cryogenic molten salt tank (3-4) and the first inlet of the first heat exchanger (1-3). An electric heating device (3-7) is installed inside the high-temperature molten salt tank (3-1), and the photovoltaic unit and molten salt energy storage unit co-controller (4-2) is connected to the electric heating device (3-7).

4. The photovoltaic-storage-thermal complementary cogeneration system as described in claim 2, characterized in that, The air outlet of the compressor (1-2) is connected to the second inlet of the first heat exchanger (1-3), the second outlet of the first heat exchanger (1-3) is connected to the second inlet of the second heat exchanger (1-4), the second outlet of the second heat exchanger (1-4) is connected to the second inlet of the third heat exchanger (1-5), the second outlet of the third heat exchanger (1-5) is connected to the air inlet of the expander (1-6), and the air outlet of the expander (1-6) is connected to the air inlet of the compressor (1-2). The second outlet of the second heat exchanger (1-4) is also connected to the gas storage tank (1-8), and the gas storage tank (1-8) is also connected to the second inlet of the third heat exchanger (1-5).

5. The solar-storage-thermal complementary cogeneration system as described in claim 4, characterized in that, A fourth control valve (8) is installed on the pipeline between the second outlet of the second heat exchanger (1-4) and the second inlet of the third heat exchanger (1-5); A fifth control valve (9) is installed on the pipeline between the second outlet of the second heat exchanger (1-4) and the gas storage tank (1-8), and a sixth control valve (10) is installed on the pipeline between the gas storage tank (1-8) and the second inlet of the third heat exchanger (1-5). A seventh control valve (11) is installed on the pipeline between the air outlet of the expander (1-6) and the air inlet of the compressor (1-2).

6. The solar-storage-thermal complementary cogeneration system as described in claim 1, characterized in that, It also includes the aforementioned collaborative control unit (4); The aforementioned collaborative control unit (4) is connected to an external power source; The collaborative control unit (4) is also connected to the motor (1-1) and the high-temperature molten salt tank (3-1) respectively, for sending the electrical energy generated by the photovoltaic unit (2) to the motor (1-1), the high-temperature molten salt tank (3-1) or directly outputting it; Furthermore, the coordinating control unit (4) connects the electrical load and the thermal load, and can provide feedback on the electrical load and thermal load requirements.

7. A method for combined heat and power (CHP) that integrates photovoltaic and thermal energy storage, characterized in that, It is achieved using a combined heat and power system that combines solar energy and thermal energy storage as described in any one of claims 1-6.

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