User-side coupling power supply and energy storage system

Abstract

The utility model discloses a user-side coupling power supply energy storage system, which belongs to the technical field of energy storage and comprises a high-voltage cascade power storage unit and a high-voltage fused salt heat storage unit which are connected with a high-voltage alternating-current bus through a high-voltage switch cabinet. According to the user-side coupling power supply energy storage system adopting the structure, the high-voltage cascade type energy storage unit capable of being directly hung at high voltage and the high-voltage fused salt heat storage unit are coupled for use, an obvious cooperative and complementary effect is achieved on the user side, no transformer is needed, the step of voltage boosting and transformation of the transformer and high loss of a large-current line are reduced, and the power supply efficiency is improved. The system efficiency of electricity storage and heat storage at the user side is greatly improved, the energy conversion efficiency is improved, and the investment cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage, in particular to a user-side coupled power supply energy storage system. Background Art

[0002] Traditional electrochemical energy storage typically uses a low-voltage parallel connection method, where a large number of battery clusters are connected to the grid via a high-power energy storage inverter and a transformer to boost the voltage. Due to the large number of batteries connected in parallel, the charging current is unbalanced between multiple battery clusters in the low-voltage battery energy storage system, resulting in low battery utilization and energy storage efficiency. In addition, a large number of transformers and switchgear are required, which increases system costs.

[0003] Existing technologies using molten salt for user-side energy storage and power supply have a low electricity-to-heat-to-electricity conversion efficiency of approximately 40%. Using low-voltage electric heaters for molten salt heating reduces system efficiency due to transformer voltage step-up and losses in high-current circuits. Currently, the most commonly used heaters are electric heating tubes, which require a large number of them for high-power applications. Operating these heaters in high-temperature molten salt environments can lead to problems such as surface overheating, insulation failure, and insufficient reliability and corrosion resistance. Utility Model Content

[0004] The purpose of this utility model is to provide a user-side coupled power supply and energy storage system to solve the above problems.

[0005] To achieve the above objectives, the present invention provides a user-side coupled power supply and energy storage system, including a high-voltage cascade power storage unit and a high-voltage molten salt heat storage unit, both of which are connected to the high-voltage AC bus through a high-voltage switchgear.

[0006] Preferably, the high-voltage cascade power storage unit includes an AC connection device and several energy storage containers. The several energy storage containers are arranged in parallel and connected to the AC connection device. A PCS cabinet is arranged in the energy storage container. The PCS cabinet in each energy storage container is connected to the EMS cabinet and the main control container.

[0007] Preferably, the AC connection device includes a grid-connected reactor cabinet, a starting cabinet and an incoming line cabinet connected in sequence, and the incoming line cabinet is connected to the high-voltage switch cabinet.

[0008] Preferably, a plurality of energy storage mechanisms connected in series are provided in the energy storage container, and the energy storage mechanisms include a DC / AC power module and a battery cluster connected to the DC / AC power module.

[0009] Preferably, a liquid cooler and a fire extinguishing cabinet are provided in the energy storage container, the liquid cooler is connected to the main control container, a supporting wheel group is provided at the bottom of the fire extinguishing cabinet, and the supporting wheel group is provided on a slide rail in the energy storage container.

[0010] Preferably, the high-voltage molten salt heat storage unit includes a molten salt electrode boiler connected to the high-voltage switchgear, the molten salt electrode boiler is connected to a first molten salt pump and a second molten salt tank, the first molten salt pump is arranged in the first molten salt tank, the second molten salt pump is arranged in the second molten salt tank, and a heat exchanger is arranged between the second molten salt pump and the first molten salt tank.

[0011] Preferably, the water inlet of the heat exchanger is connected to a pipeline pump, which is connected to a softening water device; the water outlet of the heat exchanger is connected to a steam cylinder or a radiator, which is connected to the pipeline pump through a pipeline.

[0012] Therefore, the present invention adopts a user-side coupled power supply and energy storage system with the above structure, which has the following beneficial effects: the use of a high-voltage cascade energy storage unit that can be directly connected at high voltage and a high-voltage molten salt heat storage unit in coupling, has obvious synergistic and complementary effects on the user side, does not require the use of a transformer, reduces the transformer step-up and transformation link and the high loss of the high-current line, not only greatly improves the system efficiency of power and heat storage on the user side, improves the energy conversion efficiency, but also helps to reduce investment costs. The high-voltage cascade energy storage unit directly supplies power to the high-voltage molten salt heat storage unit through the high-voltage AC bus, further improving the system efficiency. The high electrical conductivity of the molten salt itself acts as a heating resistor, which can achieve high-voltage direct connection. Compared with the comprehensive efficiency of electricity-heat-electricity of 40%, the comprehensive efficiency of heat storage and heating on the user side can reach about 90%. Through the combined use of thermoelectric coupling energy storage, efficient and stable peak shaving and valley filling on the user side can be achieved, thereby improving the economic benefits on the user side.

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of Example 1 of a user-side coupled power supply and energy storage system of the utility model;

[0015] Figure 2 This is a schematic diagram of the structure of the support wheel group of the utility model;

[0016] Figure 3 This is a structural diagram of Example 2 of a user-side coupled power supply and energy storage system of the utility model.

[0017] Reference numerals

[0018] 1. High-voltage cascade power storage unit; 11. Energy storage container; 1101. DC / AC power module; 1102. Battery cluster; 1103. Liquid cooler; 1104. PCS cabinet; 1105. Slide rail; 1106. Fire cabinet; 1107. Support wheel assembly; 12. Grid-connected reactor cabinet; 13. Starter cabinet; 14. Incoming line cabinet; 15. Main control container; 16. EMS cabinet;

[0019] 2. High-pressure molten salt heat storage unit; 21. Molten salt electrode boiler; 22. First molten salt tank; 221. First molten salt pump; 23. Second molten salt tank; 231. Second molten salt pump; 24. Heat exchanger; 25. Steam distribution cylinder; 26. Softening water device; 27. Radiator; 28. Pipeline pump;

[0020] 3. High-voltage AC busbar; 4. High-voltage switchgear. DETAILED DESCRIPTION

[0021] Example

[0022] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the present invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as a limitation on the present invention.

[0023] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0024] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings.

[0025] Example 1

[0026] like Figure 1 As shown, a user-side coupled power supply and energy storage system includes a high-voltage cascade power storage unit 1 and a high-voltage molten salt heat storage unit 2. The high-voltage cascade power storage unit 1 and the high-voltage molten salt heat storage unit 2 are both connected to the high-voltage AC bus 3 through a high-voltage switchgear 4, and the voltage level is 6-35KV.

[0027] The high-voltage cascade power storage unit 1 includes an AC connection device and several energy storage containers 11. These containers 11 are connected in parallel to the AC connection device. A PCS cabinet 1104 is installed within each energy storage container 11. Each PCS cabinet 1104 in each energy storage container 11 is connected to an EMS cabinet 16 and a master control container 15. The AC connection device includes a grid-connected reactor cabinet 12, a starter cabinet 13, and an incoming line cabinet 14, which are connected in sequence. The incoming line cabinet 14 is connected to the high-voltage switch cabinet 4. The grid-connected reactor cabinet 12 can reduce transient overvoltage and current to ensure system stability. The energy storage container 11 is equipped with several series-connected energy storage mechanisms, including a DC / AC power module 1101 and a battery cluster 1102 connected to the DC / AC power module 1101. The energy storage container 11 is provided with a liquid cooler 1103 and a fire extinguisher cabinet 1106. The liquid cooler 1103 is connected to the main control container 15. The coolant can circulate to remove excess heat from the energy storage mechanism, thereby ensuring that the battery cluster 1102 operates within the optimal temperature range. Figure 2 As shown, a support wheel set 1107 is provided at the bottom of the fire cabinet 1106, and the support wheel set 1107 is set on the slide rail 1105 in the energy storage container 11 to facilitate the movement of the fire cabinet 1106.

[0028] The high-voltage molten salt heat storage unit 2 includes a molten salt electrode boiler 21 connected to the high-voltage switchgear 4. The molten salt electrode boiler 21 is connected to a first molten salt pump 221 and a second molten salt tank 23. The first molten salt pump 221 is disposed in the first molten salt tank 22, and the second molten salt tank 23 is disposed in the second molten salt tank 23. A heat exchanger 24 is disposed between the second molten salt pump 231 and the first molten salt tank 22. In this embodiment, the water outlet of the heat exchanger 24 is connected to a steam distribution cylinder 25, and the water inlet of the heat exchanger 24 is connected to a pipeline pump 28. The pipeline pump 28 is connected to a softening water device 26 to provide high-temperature steam.

[0029] The specific tasks are as follows:

[0030] During off-peak hours, high-voltage cascaded storage units 1 and high-voltage molten salt thermal storage units 2 are prioritized for energy storage. Both high-voltage cascaded storage units 1 and 2 are directly connected via high-voltage direct-hook technology. High-voltage cascaded storage units 1 utilize a cascaded topology, effectively resolving the problem of uneven charging current between multiple battery clusters 1102 in traditional low-voltage battery energy storage systems. While achieving synchronous conversion of high-voltage, large-capacity energy storage, this significantly reduces the energy loss of the energy storage system's charging and discharging. Battery clusters 1102 are dispersed throughout each energy storage mechanism. The DC / AC power modules 1101 within the energy storage mechanisms convert AC power into DC power, which is then stored in the battery clusters 1102. Each energy storage mechanism outputs several hundred volts of AC voltage. A three-phase star-connected cascaded H-bridge topology is employed, allowing for input of 6-35 kV three-phase AC voltage and transformerless access to the AC grid. Multiple energy storage containers 11, after passing through the grid-connected reactor cabinet 12, are sequentially connected to the starter cabinet 13, incoming line cabinet 14, high-voltage switchgear 4, and high-voltage AC busbar 3 to achieve charging.

[0031] The high-pressure molten salt thermal storage unit 2 is equipped with a first molten salt tank 22, a first molten salt pump 221, a molten salt electrode boiler 21, a second molten salt tank 23, a second molten salt pump 231, and a heat exchanger 24, which are connected in sequence via molten salt pipelines. During off-peak hours, the first molten salt pump 221 transports the low-temperature molten salt from the first molten salt tank 22 through pipelines to the molten salt electrode boiler 21. The molten salt electrode boiler 21 uses high-voltage electricity to drive the high-voltage electrode plates to discharge. Due to the high conductivity of the molten salt, the molten salt itself acts as a heating resistor, and after heating, it becomes high-temperature molten salt. The high-temperature molten salt is then transported and stored in the second molten salt tank 23. The molten salt electrode boiler 21 uses molten salt as a medium, converting off-peak electricity into thermal energy for storage via high-voltage, high-power high-voltage electrode plates.

[0032] During peak power periods, the electrical energy stored in the battery cluster 1102 is converted from direct current to alternating current. Each energy storage unit outputs an AC voltage of several hundred volts. A three-phase star-connected cascaded H-bridge topology is adopted to output a three-phase AC voltage of 6-35kV. Transformerless access to the AC grid is achieved. After passing through the grid-connected reactor cabinet 12, multiple energy storage containers 11 are sequentially connected to the starter cabinet 13, incoming line cabinet 14, high-voltage switch cabinet 4, and high-voltage AC busbar 3 to achieve the discharge function.

[0033] The second molten salt pump 231 transports the high-temperature molten salt to the heat exchanger 24 through a pipeline, and generates high-temperature steam after heat exchange with water. The high-temperature steam is transported to the steam cylinder 25 through a steam pipeline. The steam in the steam cylinder 25 is separated and transported to the process heat unit to meet the industrial steam demand. High-parameter steam can be output when using heat.

[0034] Example 2

[0035] like Figure 3As shown, this embodiment differs from Example 1 in that the water outlet of heat exchanger 24 is connected to radiator 27, which is connected to pipeline pump 28 via a pipe to provide heating. Pipe pump 28, heat exchanger 24, and radiator 27 form a circulation path. Softening water device 26 is connected to the water inlet of pipeline pump 28 via a water supply pipe. Heat exchanger 24 provides high-temperature hot water, which is transported to radiator 27 via pipeline pump 28 to provide heat to the building. This structural combination achieves heating for user-side buildings.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A user-side coupled power supply and energy storage system, characterized in that: It includes a high-voltage cascade power storage unit and a high-voltage molten salt heat storage unit, both of which are connected to the high-voltage AC bus through a high-voltage switch cabinet.

2. A user-side coupled power supply and energy storage system according to claim 1, characterized in that: The high-voltage cascade power storage unit includes an AC connection device and several energy storage containers. The several energy storage containers are arranged in parallel and connected to the AC connection device. A PCS cabinet is arranged in the energy storage container. The PCS cabinet in each energy storage container is connected to the EMS cabinet and the main control container.

3. A user-side coupled power supply and energy storage system according to claim 2, characterized in that: The AC connection device comprises a grid-connected reactor cabinet, a starter cabinet and an incoming line cabinet which are connected in sequence, and the incoming line cabinet is connected to the high-voltage switch cabinet.

4. A user-side coupled power supply and energy storage system according to claim 3, characterized in that: A plurality of series-connected energy storage mechanisms are arranged in the energy storage container, and the energy storage mechanisms include a DC / AC power module and a battery cluster connected to the DC / AC power module.

5. A user-side coupled power supply and energy storage system according to claim 4, characterized in that: A liquid cooler and a fire extinguishing cabinet are arranged in the energy storage container. The liquid cooler is connected to the main control container. A supporting wheel group is arranged at the bottom of the fire extinguishing cabinet. The supporting wheel group is arranged on a slide rail in the energy storage container.

6. A user-side coupled power supply and energy storage system according to claim 1, characterized in that: The high-voltage molten salt heat storage unit includes a molten salt electrode boiler connected to a high-voltage switch cabinet, the molten salt electrode boiler is connected to a first molten salt pump and a second molten salt tank, the first molten salt pump is arranged in the first molten salt tank, the second molten salt pump is arranged in the second molten salt tank, and a heat exchanger is arranged between the second molten salt pump and the first molten salt tank.

7. A user-side coupled power supply and energy storage system according to claim 6, characterized in that: The water inlet end of the heat exchanger is connected with a pipeline pump, which is connected with a softening water device; the water outlet end of the heat exchanger is connected with a sub-cylinder or a radiator, which is connected with the pipeline pump through a pipeline.

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