Photovoltaic energy storage system and photovoltaic energy storage method

Abstract

The present application relates to the technical field of energy storage, and discloses a photovoltaic energy storage system and a photovoltaic energy storage method, the photovoltaic energy storage system comprising a photovoltaic power generation unit, the photovoltaic power generation unit being connected with a power supply network, a gas compression unit being connected with the photovoltaic power generation unit, a heat and gas storage unit being communicated with the gas compression unit, a turbine expansion power generation unit comprising a turbine expansion generator, an air inlet of the turbine expansion generator being communicated with the heat and gas storage unit, and a power transmission side of the turbine expansion generator being communicated with the power supply network; a first heat exchanger low-temperature side inlet being communicated with a turbine expansion generator air outlet, and a cold storage unit comprising a cold storage tank, an inlet of the cold storage tank being communicated with a first heat exchanger high-temperature side outlet, an outlet of the cold storage tank being communicated with the photovoltaic power generation unit, and the cold storage tank being used for cooling the photovoltaic power generation unit. The present application solves the problems of the prior art, such as the temperature rise of the photovoltaic cell panel, the reduction of the photoelectric conversion efficiency of the photovoltaic cell panel, the insufficient energy storage of the energy storage unit, and the inability to release sufficient electric energy in time.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a photovoltaic energy storage system and a photovoltaic energy storage method. Background Technology

[0002] Photovoltaic energy storage systems are integrated energy systems combining photovoltaic power generation and energy storage. They offer advantages such as stable power supply and consistent power output, and have been widely used in new energy power supply systems. A photovoltaic energy storage system consists of a photovoltaic power generation unit and an energy storage unit. The photovoltaic power generation unit first utilizes the photovoltaic effect of semiconductor photovoltaic panels to directly convert solar radiation energy into direct current (DC), which is then converted into alternating current (AC) by an inverter and transmitted to the power grid. The energy storage unit stores excess energy generated by the photovoltaic power generation unit. When sunlight is insufficient or the electricity load increases, the pre-stored excess energy is released to the power grid, thus ensuring a continuous and stable power supply to the grid from the photovoltaic energy storage system.

[0003] However, when sunlight shines on the surface of photovoltaic panels, some solar radiation energy is converted into heat energy, causing the temperature of the photovoltaic panels to rise. This, in turn, alters the current-carrying characteristics inside the photovoltaic panels, leading to a decrease in the open-circuit voltage and output power, and consequently, a reduction in the photoelectric conversion efficiency. This decrease in photoelectric conversion efficiency reduces the electrical output of the photovoltaic power generation unit, resulting in insufficient energy storage in the energy storage unit. When sunlight is insufficient or the electrical load increases, the energy storage unit cannot release enough electrical energy in time, causing partial power outages in the grid. Summary of the Invention

[0004] The technical problem to be solved by this invention is to improve the photoelectric conversion efficiency of photovoltaic panels and increase the power output of photovoltaic power generation units.

[0005] To address the aforementioned technical problems, the present invention provides a photovoltaic energy storage system, comprising: A photovoltaic power generation unit is used to convert solar radiation energy into electrical energy. The photovoltaic power generation unit is connected to the power grid. A gas compression unit, connected to the photovoltaic power generation unit, is used to compress air. The thermal and gas storage unit is connected to the gas compression unit and is used to store the compressed air output by the gas compression unit. The turbine expansion power generation unit includes at least one turbine expansion generator. The air inlet of the turbine expansion generator is connected to the thermal and gas storage unit. The turbine expansion generator is used to receive compressed air output from the gas compression unit to generate electricity. The transmission side of the turbine expansion generator is connected to the power grid. The first heat exchanger has its low-temperature side inlet connected to the outlet of the turbine expansion generator, and is used to receive the cold air output by the turbine expansion generator unit. The high-temperature side inlet of the first heat exchanger is used to introduce the heat medium, and the heat medium and the cold air exchange heat to form the first cold medium. The cold storage unit includes at least one cold storage tank for storing a first refrigerant. The inlet of the cold storage tank is connected to the high-temperature side outlet of the first heat exchanger, and the outlet of the cold storage tank is connected to the photovoltaic power generation unit for cooling the photovoltaic power generation unit.

[0006] Preferably, the photovoltaic power generation unit includes a support plate, a photovoltaic panel, heat dissipation fins, and cooling pipes; Multiple photovoltaic panels are installed, and each photovoltaic panel is fixed to the top of the support plate and connected to the power grid. Multiple heat dissipation fins are provided, and the multiple heat dissipation fins are fixed to the bottom of the support plate; There are multiple cooling pipes, each fixed to the bottom of multiple heat dissipation fins, and each cooling pipe is connected to the outlet of the cold storage tank.

[0007] Preferably, multiple heat dissipation fins are arranged at intervals in the horizontal direction, and each heat dissipation fin is arranged vertically; Multiple cooling pipes are arranged at intervals along the length of the heat dissipation fins, and each cooling pipe extends along the interval direction of the heat dissipation fins. Each heat dissipation fin has a mounting groove at its bottom that matches each cooling pipe, and the cooling pipe is fixedly installed in the mounting groove.

[0008] Preferably, the thermal and gas storage unit includes: The second heat exchanger has its high-temperature side inlet connected to the gas compression unit, and its low-temperature side inlet is used to introduce the second refrigerant. The high-temperature storage tank is connected to the low-temperature side outlet of the second heat exchanger; The gas storage tank is connected to the high-temperature side outlet of the second heat exchanger; The third heat exchanger has its high-temperature side inlet connected to the high-temperature storage tank, its low-temperature side inlet connected to the gas storage tank, and its low-temperature side outlet connected to the air inlet of the turbine expansion generator.

[0009] Preferably, the gas compression unit includes N compressors connected in sequence, where N is an integer greater than 1; The inlet of the first compressor is connected to air; The outlet of the a-th compressor is connected to the inlet of the (a+1)-th compressor, where a is an integer from 1 to N-1; The outlet of the Nth compressor is connected to the high-temperature side inlet of the second heat exchanger.

[0010] Preferably, the turbine expansion power generation unit includes M turbine expansion generators connected in sequence, where M is an integer greater than 1; The air inlet of the first turbine expander is connected to the low-temperature outlet of the third heat exchanger; The outlet of the b-th turbine expander is connected to the inlet of the (b+1)-th turbine expander, where b is an integer from 1 to M-1. The outlet of the Mth turbine expander is connected to the low-temperature side inlet of the first heat exchanger.

[0011] This invention provides a photovoltaic energy storage method, employing the aforementioned photovoltaic energy storage system, comprising the following steps: S1. Start the photovoltaic power generation unit to generate electricity; S2. When the power generation of the photovoltaic power generation unit exceeds the demand of the power grid, the gas compression unit is activated to compress air to consume the excess power generated by the photovoltaic power generation unit, and the compressed air is stored in the thermal storage and gas storage unit. S3. When the power generation of the photovoltaic power generation unit is less than the demand of the power grid, the gas in the thermal storage and gas storage unit is transported to the turbine expansion power generation unit to generate electricity in order to supplement the power shortage required by the power grid. S4. Input the cold air generated by the turbine expansion power generation unit into the first heat exchanger and deliver the heat medium into the first heat exchanger so that the heat medium and the cold air exchange heat to form the first cold medium, and store the first cold medium in the cold storage unit. S5. When the photovoltaic power generation unit reaches the preset temperature, the first refrigerant in the cold storage unit is delivered to the photovoltaic power generation unit for cooling.

[0012] Preferably, in step S2, when the power generation of the photovoltaic power generation unit exceeds the demand of the power grid, the gas compression unit is activated to compress air to consume the excess electricity generated by the photovoltaic power generation unit, specifically: The power generation of the photovoltaic power generation unit is monitored in real time, and the power demand of the power grid is the excess power. Then, the compressor is started to compress air and the operating power of the compressor is adjusted so that the total operating power of the gas compression unit is close to the excess power, until the power generation is less than the power demand.

[0013] Preferably, the high-temperature storage tank is connected to the high-temperature side inlet of the third heat exchanger through a first pipeline, and a first valve is provided on the first pipeline; the gas storage tank is connected to the low-temperature side inlet of the third heat exchanger through a second pipeline, and a second valve is provided on the second pipeline. In step S3, when the power generation of the photovoltaic power generation unit is less than the demand of the power grid, the turbine expansion power generation unit is activated to generate electricity to supplement the power shortage required by the power grid, specifically: The power generation of the photovoltaic power generation unit and the power demand of the power grid are monitored in real time. The difference between the power demand and the power generation is the power shortage. Then, the first valve and the second valve are opened to start each turbine expansion generator to generate electricity. The opening degree of the first valve and / or the second valve is adjusted so that the total power generation of the turbine expansion power generation unit is close to the power shortage until the power generation is greater than the power demand.

[0014] Preferably, a first temperature sensor is provided at the outlet of the turbine expansion power generation unit to detect the temperature of the cold air flowing out of the turbine expansion power generation unit; In step S4, when the cold air generated by the turbine expansion power generation unit is input into the first heat exchanger, the temperature of the cold air measured by the first temperature sensor is monitored in real time. When the temperature of the cold air is greater than the preset temperature of the photovoltaic power generation unit, the opening of the first valve and / or the second valve is adjusted so that the temperature of the cold air is less than the preset temperature of the photovoltaic power generation unit.

[0015] Compared with the prior art, the photovoltaic energy storage system and photovoltaic energy storage method of the present invention have the following advantages: This invention discloses a photovoltaic energy storage system and method. A first heat exchanger exchanges heat between the cold air generated by a turbine expansion power generation unit and a heat transfer medium. The heat transfer medium becomes a first refrigerant, which is stored in a cold storage unit. When the photovoltaic power generation unit reaches a preset temperature, the first refrigerant in the cold storage unit is used to cool it down, effectively reducing the operating temperature of the photovoltaic panels, thereby improving photoelectric conversion efficiency, increasing the power output of the photovoltaic power generation unit, and avoiding the problem of insufficient energy storage due to insufficient power generation in the thermal and gas storage unit. When power generation is excessive, the gas compression unit converts the sufficient electrical energy into the potential energy and thermal energy of compressed air, which is stored in the thermal and gas storage unit. When power generation is insufficient, the stored energy is released through the turbine expansion power generation unit to supplement the power grid, ensuring that the thermal and gas storage unit can release sufficient electrical energy in a timely manner when there is insufficient sunlight or increased power load, thus avoiding partial power outages in the power grid.

[0016] Furthermore, the gas compression unit consumes excess electricity from the photovoltaic power generation unit to compress air, converting electrical energy into the potential and thermal energy of the compressed air and storing it in the thermal and gas storage unit, thus avoiding the waste of excess electrical energy. When the turbine expansion power generation unit is working, it can not only supplement the power grid with the power shortage, but the cold air it generates is not directly discharged. Instead, it exchanges heat between the heat medium and the cold air through the first heat exchanger to form the first refrigerant. The first refrigerant carries the cold energy and stores it in the cold storage unit and is used to cool the photovoltaic panels, thereby improving the energy utilization efficiency of the entire photovoltaic energy storage system and reducing energy loss.

[0017] This invention connects a photovoltaic power generation unit to the power grid, enabling real-time power supply. A gas compression unit, a thermal and gas storage unit, and a turbine expansion power generation unit form an energy storage and power replenishment circuit. A cold storage unit ensures the normal operation of the photovoltaic power generation unit. All units work together to ensure stable operation of the system under different lighting conditions and different power loads. This invention solves the technical problems in the prior art where the temperature of the photovoltaic panel rises, causing a decrease in the photoelectric conversion efficiency of the photovoltaic panel, and the energy storage unit is insufficient to store enough energy and cannot release enough electrical energy in time. Attached Figure Description

[0018] Figure 1 This is a system diagram of an embodiment of the present invention; Figure 2 This is a structural diagram of a photovoltaic power generation unit according to an embodiment of the present invention.

[0019] In the diagram, 1. Photovoltaic power generation unit; 11. Support plate; 12. Photovoltaic panel; 13. Heat dissipation fins; 14. Cooling pipe; 2. Gas compression unit; 3. Thermal and gas storage unit; 31. Second heat exchanger; 311. Third valve; 312. Fourth valve; 32. High-temperature storage tank; 321. First pipeline; 322. First valve; 33. Gas storage tank; 331. Second pipeline; 332. Second valve; 34. Third heat exchanger; 4. Turbine expansion power generation unit; 5. First heat exchanger; 6. Cooling unit; 61. Fifth valve; 62. Sixth valve; 7. Controller; 8. Power grid. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "bottom", "inner", "outer" and other terms used in this invention to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] It should be understood that the terms "first," "second," etc., are used in this invention to describe various types of information, but these terms are not limited to them; they are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] like Figure 1 and Figure 2 As shown, a photovoltaic energy storage system according to a preferred embodiment of the present invention includes a photovoltaic power generation unit 1, a gas compression unit 2, a thermal and gas storage unit 3, a turbine expansion power generation unit 4, a first heat exchanger 5, and a cold storage unit 6. The connection relationship between the units is shown in the figure. Figure 1 The solid line portion.

[0025] Specifically, such as Figure 1 and Figure 2 As shown, the photovoltaic power generation unit 1 is used to convert solar radiation energy into electrical energy, and the photovoltaic power generation unit 1 is connected to the power grid 8. In this embodiment of the invention, the photovoltaic power generation unit 1 includes a support plate 11, photovoltaic panels 12, heat dissipation fins 13, and cooling pipes 14. Multiple photovoltaic panels 12 are provided, and multiple photovoltaic panels 12 are fixed to the top of the support plate 11. Each photovoltaic panel 12 includes multiple monocrystalline silicon solar cells connected in series or in parallel. Each photovoltaic panel 12 is connected to the power grid 8. Since the photovoltaic panels 12 produce direct current (DC), while the power grid 8 requires alternating current (AC), the photovoltaic power generation unit 1 also includes an inverter connecting the photovoltaic panels 12 and the power grid 8 to convert the DC power produced by the photovoltaic panels 12 into AC power before inputting it into the power grid 8.

[0026] In this embodiment of the invention, the support plate 11 in the photovoltaic power generation unit 1 is an aluminum plate, used to support the photovoltaic panel 12 and conduct the heat of the photovoltaic panel 12 to the heat dissipation fins 13; there are multiple heat dissipation fins 13, each made of aluminum, fixed to the bottom of the support plate 11 and arranged at intervals in the horizontal direction, and arranged vertically, which can dissipate some of the heat of the photovoltaic panel 12 to the surrounding air and transfer some of the heat to the cooling pipes 14; there are multiple cooling pipes 14, each made of copper, arranged at intervals along the length of the heat dissipation fins 13, and extending along the interval direction of the heat dissipation fins 13; the bottom of each heat dissipation fin 13 is provided with a mounting groove that matches each cooling pipe 14, the cooling pipe 14 is fixedly installed in the mounting groove, and each cooling pipe 14 is connected to the outlet of the cold storage tank. Once the photovoltaic panel 12 reaches the preset temperature, the first refrigerant in the cold storage tank of the cold storage unit 6 flows through the cold transfer pipe 14. The first refrigerant absorbs the heat transferred from the photovoltaic panel 12 to the heat dissipation fins 13 and the cold transfer pipe 14, thereby cooling the photovoltaic panel 12. The support plate 11, photovoltaic panel 12, heat dissipation fins 13, and cold transfer pipe 14 are all fixed together with EVA (ethylene-vinyl acetate copolymer) adhesive.

[0027] Specifically, such as Figure 1 As shown, the gas compression unit 2 is connected to the photovoltaic power generation unit 1, and the gas compression unit 2 is used to compress air. In this embodiment of the invention, the gas compression unit 2 includes N compressors connected in sequence, where N is an integer greater than 1; the inlet of the first compressor is connected to air, the outlet of the a-th compressor is connected to the inlet of the (a+1)-th compressor, where a is an integer from 1 to N-1, and the outlet of the N-th compressor is connected to the high-temperature side inlet of the second heat exchanger 31. When the power generation of the photovoltaic power generation unit 1 is greater than the demand of the power grid 8, the compressors in the gas compression unit 2 are started. After the air is drawn in by the first compressor, it is compressed in sequence by multiple compressors to form high-temperature and high-pressure gas, so as to convert the electrical energy of the photovoltaic power generation unit 1 into the internal energy of the high-temperature and high-pressure gas, so as to use it for power generation of the turbine expansion power generation unit 4 during peak electricity consumption periods.

[0028] Specifically, such as Figure 1As shown, the heat and gas storage unit 3 is connected to the gas compression unit 2 and is used to store the compressed air output by the gas compression unit 2. The heat and gas storage unit 3 includes a second heat exchanger 31, a high-temperature storage tank 32, a gas storage tank 33, a third heat exchanger 34, and a low-temperature storage tank. In this embodiment of the invention, the second refrigerant is molten salt. The low-temperature storage tank is used to store the second refrigerant. The outlet of the low-temperature storage tank is connected to the low-temperature side inlet of the second heat exchanger 31, and the high-temperature storage tank 32 is connected to the low-temperature side outlet of the second heat exchanger 31. The high-temperature side inlet of the second heat exchanger 31 is connected to the outlet of the Nth compressor of the gas compression unit 2, and the high-temperature side outlet of the second heat exchanger 31 is connected to the gas storage tank 33. The high-temperature side inlet of the third heat exchanger 34 is connected to the high-temperature storage tank 32, the high-temperature side outlet of the third heat exchanger 34 is connected to the inlet of the low-temperature storage tank, the low-temperature side inlet of the third heat exchanger 34 is connected to the gas storage tank 33, and the low-temperature side outlet of the third heat exchanger 34 is connected to the air inlet of the turbine expander generator.

[0029] Specifically, the high-temperature storage tank 32 is connected to the high-temperature side inlet of the third heat exchanger 34 via a first pipeline 321, and a first valve 322 is provided on the first pipeline 321; the gas storage tank 33 is connected to the low-temperature side inlet of the second heat exchanger 31 via a second pipeline 331, and a second valve 332 is provided on the second pipeline 331; a third valve 311 is provided on the connecting pipeline between the high-temperature storage tank 32 and the low-temperature side outlet of the second heat exchanger 31; a fourth valve 312 is provided on the connecting pipeline between the gas storage tank 33 and the high-temperature side outlet of the second heat exchanger 31; and a seventh valve is provided on the connecting pipeline between the low-temperature storage tank and the low-temperature side inlet of the second heat exchanger 31.

[0030] When the power generation of photovoltaic power generation unit 1 exceeds the demand of power grid 8, the seventh valve, the third valve 311, and the fourth valve 312 are opened. The high-temperature and high-pressure gas generated by gas compression unit 2 passes through the high-temperature side of the second heat exchanger 31. Molten salt enters the second heat exchanger 31 from the low-temperature storage tank and exchanges heat with the high-temperature and high-pressure gas. The molten salt absorbs the heat from the high-temperature and high-pressure gas and enters the high-temperature storage tank 32 for storage, thus realizing the recovery of compression heat. At the same time, the high-temperature and high-pressure gas is cooled down to become high-pressure gas and enters the gas storage tank 33 for storage. Through the above process, the system not only avoids the waste of compression heat energy and improves the overall energy utilization efficiency, but also smooths the fluctuations in heat load and gas pressure through the buffering capacity of the heat storage and gas storage unit, enhancing the system's operational stability under varying operating conditions. Meanwhile, the recovered heat energy can be used for power generation or heating at any time, reducing the dependence on additional cooling or heating equipment and reducing operating costs.

[0031] When the power generation of photovoltaic power generation unit 1 is less than the demand of power grid 8, the first valve 322 and the second valve 332 are opened, and the molten salt in the high-temperature storage tank 32 enters the third heat exchanger 34. At the same time, the high-pressure gas in the gas storage tank 33 enters the third heat exchanger 34 and exchanges heat with the molten salt. The high-temperature gas after absorbing heat becomes high-temperature and high-pressure gas. The high-temperature and high-pressure gas enters the turbine expansion generator in the turbine expansion power generation unit 4 to generate electricity, while the cooled molten salt returns to the low-temperature storage tank for recycling.

[0032] Specifically, such as Figure 1 As shown, the turbine expansion power generation unit 4 includes at least one turbine expansion generator. The air inlet of the turbine expansion generator is connected to the thermal energy storage unit 3. The turbine expansion generator is used to receive compressed air output from the gas compression unit 2 for power generation. The transmission side of the turbine expansion generator is connected to the power grid 8. In this embodiment of the invention, the turbine expansion power generation unit 4 includes M turbine expansion generators connected in sequence, where M is an integer greater than 1. The air inlet of the first turbine expansion generator is connected to the low-temperature side outlet of the third heat exchanger 34 in the thermal energy storage unit 3. The air outlet of the b-th turbine expansion generator is connected to the air inlet of the (b+1)-th turbine expansion generator, where b is an integer from 1 to M-1. The air outlet of the M-th turbine expansion generator is connected to the low-temperature side inlet of the first heat exchanger 5. The high-temperature, high-pressure gas flowing out of the third heat exchanger 34 enters the first turbine expander generator and is then used by multiple turbine expanders to convert the internal energy of the high-temperature, high-pressure gas into electrical energy and transmit it to the power grid 8. After absorbing heat, the high-temperature, high-pressure gas forms cold gas and enters the first heat exchanger 5.

[0033] Specifically, such as Figure 1As shown, the low-temperature inlet of the first heat exchanger 5 is connected to the outlet of the Mth turbine expander generator, and is used to receive the cold air output by the turbine expander generator unit 4. The high-temperature inlet of the first heat exchanger 5 is used to introduce a heat medium, which exchanges heat with the cold air to form a first refrigerant. The cold storage unit 6 includes at least one cold storage tank, which is used to store the first refrigerant. The inlet of the cold storage tank is connected to the high-temperature outlet of the first heat exchanger 5, and the outlet of the cold storage tank is connected to the cooling pipe 14 of the photovoltaic generator unit 1, for cooling the photovoltaic generator unit 1. A fifth valve 61 is provided on the connecting pipe between the cold storage tank and the first heat exchanger 5, and a sixth valve 62 is provided on the connecting pipe between the cold storage tank and the cooling pipe 14. In this embodiment of the invention, the photovoltaic energy storage system also includes a water storage tank containing a heat transfer medium, which is water. The outlet of the water storage tank is connected to the high-temperature side inlet of the first heat exchanger 5. An eighth valve is provided on the connecting pipeline. After the eighth valve is opened, water enters the first heat exchanger 5 from the water storage tank and exchanges heat with the cold air. After being cooled by the cold air, the water forms a first refrigerant that enters the cold storage tank for storage. When the photovoltaic power generation unit 1 reaches the preset temperature, the first refrigerant in the cold storage unit 6 is transported to the cold transmission pipe 14 to absorb the heat of the photovoltaic panel 12, thereby cooling the photovoltaic power generation unit 1.

[0034] Furthermore, in this embodiment of the invention, a second temperature sensor is provided on the photovoltaic panel 12 in the photovoltaic power generation unit 1 to detect the temperature of the photovoltaic panel 12; a first temperature sensor is provided at the outlet of the turbine expansion power generation unit 4 (i.e., at the outlet of the Mth turbine expansion generator) to detect the temperature of the cold air flowing out of the turbine expansion power generation unit 4.

[0035] Furthermore, in this embodiment of the invention, the photovoltaic energy storage system also includes a controller 7, which is electrically connected to a first temperature sensor, a second temperature sensor, a photovoltaic power generation unit 1, a power grid 8, a compressor, a turbine expander generator, a first valve 322, a second valve 332, a third valve 311, a fourth valve 312, a fifth valve 61, a sixth valve 62, a seventh valve, and an eighth valve.

[0036] like Figures 1 to 2 As shown, based on the photovoltaic energy storage system of the above-described embodiments, this invention provides a photovoltaic energy storage method, including the following steps: S1. Start photovoltaic power generation unit 1 to generate electricity; In step S1, sunlight shines on the photovoltaic panel 12, which converts solar radiation energy into electrical energy. After being converted into alternating current by an inverter, the electrical energy is input into the power grid 8.

[0037] S2. When the power generation of photovoltaic power generation unit 1 is greater than the demand of power grid 8, gas compression unit 2 is activated to compress air to consume the excess power generated by photovoltaic power generation unit 1, and the compressed air is stored in thermal storage and gas storage unit 3. In step S2, the power output of the photovoltaic power generation unit 1 is compared with the demand of the power grid 8, using power as the comparison parameter. The controller 7 monitors the power output of the photovoltaic power generation unit 1 and the demand power of the power grid 8 in real time. When the power output of the photovoltaic power generation unit 1 is greater than the demand power of the power grid 8 (generally during peak power generation and off-peak power consumption), the difference between the power output and the demand power is calculated as the excess power to be absorbed. This excess power is the aforementioned excess electricity. Then, the controller 7 controls the start of each compressor to compress air and adjusts the operating power of each compressor so that the total operating power of the gas compression unit 2 is close to the excess power until the power output is less than the demand power. At the same time, the controller 7 controls the opening of the third valve 311, the fourth valve 312 and the seventh valve so that the high-temperature and high-pressure gas generated by the gas compression unit 2 enters the high-temperature storage tank 32 and the gas storage tank 33 for storage after heat exchange in the second heat exchanger 31.

[0038] In other embodiments, when the power generation approaches the required power, i.e. when the excess power is sufficiently small, the compressors stop compressing air.

[0039] S3. When the power generation of photovoltaic power generation unit 1 is less than the demand of power grid 8, the gas in thermal storage and gas storage unit 3 is transported to turbine expansion power generation unit 4 to generate electricity in order to supplement the power shortage required by power grid 8. Similarly, in step S3, the power output of the photovoltaic power generation unit 1 is compared with the demand of the power grid 8, with power as the comparison parameter. The controller 7 monitors the power output of the photovoltaic power generation unit 1 and the demand power of the power grid 8 in real time. When the power output of the photovoltaic power generation unit 1 is less than the demand power of the power grid 8 (generally during the off-peak period of power generation and peak period of power consumption), the difference between the demand power and the power output is calculated as the shortage power that needs to be supplemented. This shortage power is the aforementioned shortage of electricity. Then, the controller 7 controls the opening of the first valve 322 and the second valve 332, and starts each turbine expansion generator to generate electricity. The controller 7 adjusts the opening of the first valve 322 and / or the second valve 332 to change the gas flow rate entering the turbine expansion generator, thereby making the total power output of the turbine expansion power generation unit 4 close to the shortage power, until the power output is greater than the demand power.

[0040] In other embodiments, when the generated power approaches the required power, i.e. when the power shortage is sufficiently small, the power generation of each turbine expander is stopped.

[0041] S4. Input the cold air generated by the turbine expansion power generation unit 4 into the first heat exchanger 5, and send the heat medium into the first heat exchanger 5 so that the heat medium and the cold air exchange heat to form the first cold medium, and store the first cold medium in the cold storage unit 6. In step S4, the controller 7 controls the opening of the eighth valve and the fifth valve 61 so that the heat medium enters the first heat exchanger 5 to exchange heat with the cold air. The cooled heat medium forms the first cold medium and enters the cold storage tank for storage.

[0042] When the cold air generated by the turbine expansion generator unit 4 is input into the first heat exchanger 5, the controller 7 monitors the cold air temperature measured by the first temperature sensor in real time. When the cold air temperature is greater than 30°C, the controller 7 adjusts the opening of the first valve 322 and / or the second valve 332 to change the power generation of each turbine expansion generator, thereby making the cold air temperature less than 30°C.

[0043] S5. When the photovoltaic power generation unit 1 reaches the preset temperature, the first refrigerant in the cold storage unit 6 is delivered to the photovoltaic power generation unit 1 for cooling.

[0044] In step S5, the controller 7 monitors the temperature detected by the second temperature sensor in real time. When the temperature reading of the second temperature sensor is greater than 30°C, the controller 7 controls the opening of the sixth valve 62 to input the first refrigerant into the cooling pipe 14. The first refrigerant absorbs the heat from the photovoltaic panel 12, achieving a cooling effect. During this process, the controller 7 can adjust the opening of the sixth valve 62 in real time according to the temperature change detected by the second temperature sensor, and control the amount of first refrigerant output in real time to achieve a rapid cooling effect, while also avoiding waste of the first refrigerant's cooling capacity.

[0045] In summary, this invention provides a photovoltaic energy storage system and method. The system uses a first heat exchanger 5 to exchange heat between the cold air generated by the turbine expansion power generation unit 4 and the heat transfer medium. The heat transfer medium becomes the first refrigerant and is stored in the cold storage unit 6. When the photovoltaic power generation unit 1 reaches a preset temperature, the first refrigerant in the cold storage unit 6 is used to cool it down, effectively reducing the operating temperature of the photovoltaic panel 12, thereby improving the photoelectric conversion efficiency and increasing the power output of the photovoltaic power generation unit 1. This avoids the problem of insufficient energy storage in the thermal and gas storage unit 3 due to insufficient power generation. When there is surplus power generation, the gas compression unit 2 converts the sufficient electrical energy into the potential energy and thermal energy of compressed air and stores it in the thermal and gas storage unit 3. When power generation is insufficient, the turbine expansion power generation unit 4 releases the stored energy to supplement the power grid, ensuring that the thermal and gas storage unit 3 can release sufficient electrical energy in a timely manner when there is insufficient sunlight or increased power load, thus avoiding partial power outages in the power grid.

[0046] Furthermore, the gas compression unit 2 consumes excess electricity from the photovoltaic power generation unit 1 to compress air, converting electrical energy into the potential energy and thermal energy of the compressed air and storing it in the thermal and gas storage unit 3, thus avoiding the waste of excess electrical energy. When the turbine expansion power generation unit 4 is working, it can not only supplement the power supply grid 8 with the power shortage, but the cold air it generates is not directly discharged. Instead, it exchanges heat between the heat medium and the cold air through the first heat exchanger 5 to form the first cold medium. The first cold medium carries cold energy and stores it in the cold storage unit 6 and is used to cool the photovoltaic panels, thereby improving the energy utilization efficiency of the entire photovoltaic energy storage system and reducing energy loss.

[0047] This invention connects the photovoltaic power generation unit 1 to the power grid 8, enabling it to supply power to the power grid 8 in real time. The gas compression unit 2, the thermal and gas storage unit 3, and the turbine expansion power generation unit 4 form an energy storage and power replenishment circuit. The cold storage unit 6 ensures the normal operation of the photovoltaic power generation unit 1. All units work together to ensure that the system can operate stably under different lighting conditions and different power loads. This invention solves the technical problem in the prior art where the temperature of the photovoltaic panel rises, causing a decrease in the photoelectric conversion efficiency of the photovoltaic panel and the energy storage unit cannot release enough electrical energy in time.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A photovoltaic energy storage system, characterized in that, include: A photovoltaic power generation unit (1) is used to convert solar radiation energy into electrical energy, and the photovoltaic power generation unit (1) is connected to the power grid (8); A gas compression unit (2) is connected to the photovoltaic power generation unit (1), and the gas compression unit (2) is used to compress air; The heat storage and gas storage unit (3) is connected to the gas compression unit (2) and is used to store the compressed air output by the gas compression unit (2); The turbine expansion power generation unit (4) includes at least one turbine expansion generator. The air inlet of the turbine expansion generator is connected to the thermal storage and gas storage unit (3). The turbine expansion generator is used to receive compressed air output by the gas compression unit (2) to generate electricity. The power transmission side of the turbine expansion generator is connected to the power grid (8). The first heat exchanger (5) has a low-temperature side inlet connected to the outlet of the turbine expansion generator, and is used to receive the cold air output by the turbine expansion generator unit (4). The high-temperature side inlet of the first heat exchanger (5) is used to introduce the heat medium, and the heat medium and the cold air exchange heat to form the first cold medium. The cold storage unit (6) includes at least one cold storage tank for storing the first refrigerant. The inlet of the cold storage tank is connected to the high-temperature side outlet of the first heat exchanger (5), and the outlet of the cold storage tank is connected to the photovoltaic power generation unit (1) for cooling the photovoltaic power generation unit (1).

2. The photovoltaic energy storage system according to claim 1, characterized in that, The photovoltaic power generation unit (1) includes a support plate (11), a photovoltaic panel (12), heat dissipation fins (13) and a cooling pipe (14). The photovoltaic panel (12) is provided in multiple ways. The multiple photovoltaic panels (12) are fixed to the top of the support plate (11). Each photovoltaic panel (12) is connected to the power grid (8). The heat dissipation fins (13) are provided in multiple quantities, and the multiple heat dissipation fins (13) are fixed to the bottom of the support plate (11); The cooling pipes (14) are provided in multiple ways. Each cooling pipe (14) is fixed to the bottom of the multiple heat dissipation fins (13). Each cooling pipe (14) is connected to the outlet of the cold storage tank.

3. The photovoltaic energy storage system according to claim 2, characterized in that, The plurality of heat dissipation fins (13) are arranged at intervals in the horizontal direction, and each heat dissipation fin (13) is arranged vertically; Multiple cooling pipes (14) are arranged at intervals along the length direction of the heat dissipation fins (13), and each cooling pipe (14) extends along the interval direction of the heat dissipation fins (13). Each of the heat dissipation fins (13) has a mounting groove at its bottom that matches each of the cooling pipes (14), and the cooling pipes (14) are fixedly installed in the mounting groove.

4. The photovoltaic energy storage system according to claim 1, characterized in that, The thermal and gas storage unit (3) includes: The second heat exchanger (31) has its high-temperature side inlet connected to the gas compression unit (2), and the low-temperature side inlet of the second heat exchanger (31) is used to introduce the second refrigerant. The high-temperature storage tank (32) is connected to the low-temperature side outlet of the second heat exchanger (31); The gas storage tank (33) is connected to the high-temperature side outlet of the second heat exchanger (31); The third heat exchanger (34) has its high-temperature side inlet connected to the high-temperature storage tank (32), its low-temperature side inlet connected to the gas storage tank (33), and its low-temperature side outlet connected to the air inlet of the turbine expander.

5. The photovoltaic energy storage system according to claim 4, characterized in that, The gas compression unit (2) includes N compressors connected in sequence, where N is an integer greater than 1; The inlet of the first compressor is in communication with air; The outlet of the a-th compressor is connected to the inlet of the (a+1)-th compressor, where a is an integer from 1 to N-1; The outlet of the Nth compressor is connected to the high-temperature side inlet of the second heat exchanger (31).

6. The photovoltaic energy storage system according to claim 4, characterized in that, The turbine expansion power generation unit (4) includes M turbine expansion generators connected in sequence, where M is an integer greater than 1; The air inlet of the first turbine expander is connected to the low-temperature side outlet of the third heat exchanger (34); The outlet of the b-th turbine expander is connected to the inlet of the (b+1)-th turbine expander, where b is an integer from 1 to M-1; The outlet of the Mth turbine expander is connected to the low-temperature side inlet of the first heat exchanger (5).

7. A photovoltaic energy storage method, characterized in that, The photovoltaic energy storage system according to any one of claims 1 to 6 includes the following steps: S1. Start the photovoltaic power generation unit (1) to generate electricity; S2. When the power generation of the photovoltaic power generation unit (1) is greater than the demand of the power grid (8), the gas compression unit (2) is started to compress air to consume the excess power generated by the photovoltaic power generation unit (1) and the compressed air is stored in the heat storage and gas storage unit (3). S3. When the power generation of the photovoltaic power generation unit (1) is less than the demand of the power grid (8), the gas in the thermal storage and gas storage unit (3) is transported to the turbine expansion power generation unit (4) to generate electricity in order to supplement the power shortage required by the power grid (8). S4. The cold air generated by the turbine expansion power generation unit (4) is input into the first heat exchanger (5), and the heat medium is transported into the first heat exchanger (5) so that the heat medium and the cold air exchange heat to form the first cold medium, and the first cold medium is stored in the cold storage unit (6). S5. When the photovoltaic power generation unit (1) reaches the preset temperature, the first refrigerant in the cold storage unit (6) is delivered to the photovoltaic power generation unit (1) for cooling.

8. The photovoltaic energy storage method according to claim 7, characterized in that, In step S2, when the power generation of the photovoltaic power generation unit (1) exceeds the demand of the power grid (8), the gas compression unit (2) is activated to compress air to consume the excess power generated by the photovoltaic power generation unit (1), specifically: The power generation of the photovoltaic power generation unit (1) and the power demand of the power grid (8) are monitored in real time. The difference between the power generation and the power demand is the excess power. Then, the compressor is started to compress air and the operating power of the compressor is adjusted so that the total operating power of the gas compression unit (2) is close to the excess power until the power generation is less than the power demand.

9. The photovoltaic energy storage method according to claim 7, characterized in that, The high-temperature storage tank (32) is connected to the high-temperature side inlet of the third heat exchanger (34) through a first pipeline (321), and a first valve (322) is provided on the first pipeline (321). The gas storage tank (33) is connected to the low-temperature side inlet of the third heat exchanger (34) through a second pipeline (331), and a second valve (332) is provided on the second pipeline (331). In step S3, when the power generation of the photovoltaic power generation unit (1) is less than the demand of the power grid (8), the turbine expansion power generation unit (4) is activated to generate electricity to supplement the power shortage required by the power grid (8), specifically: The power generation of the photovoltaic power generation unit (1) and the power demand of the power grid (8) are monitored in real time. The difference between the power demand and the power generation is the power shortage. Then, the first valve (322) and the second valve (332) are opened to start each of the turbine expansion generators to generate electricity. The opening degree of the first valve (322) and / or the second valve (332) is adjusted so that the total power generation of the turbine expansion power generation unit (4) is close to the power shortage until the power generation is greater than the power demand.

10. The photovoltaic energy storage method according to claim 9, characterized in that, The turbine expansion power generation unit (4) is equipped with a first temperature sensor at its outlet to detect the temperature of the cold air flowing out of the turbine expansion power generation unit (4). In step S4, when the cold air generated by the turbine expansion power generation unit (4) is input into the first heat exchanger (5), the temperature of the cold air measured by the first temperature sensor is monitored in real time. When the temperature of the cold air is greater than the preset temperature of the photovoltaic power generation unit (1), the opening of the first valve (322) and / or the second valve (332) is adjusted so that the temperature of the cold air is less than the preset temperature of the photovoltaic power generation unit (1).

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