An array molten salt electric heating energy storage system

Abstract

The present invention relates to an array molten salt electro - heating energy storage system, which includes the first, the second to the Z - th molten salt electro - heating systems and a buffer system, where Z is a positive integer greater than 1. Among them, the heating systems at different levels have different responses to fluctuating power and heat the molten salt to different temperatures. The first, the second to the L - th molten salt electro - heating systems, where 1 ≤ L ≤ Z - 1, can quickly respond to new - energy fluctuations within a large operating condition range, enabling them to follow the changes in new - energy power, but there is also a certain fluctuation in the molten - salt outlet temperature; the molten salt output by the first L - th molten salt electro - heating systems enters the buffer system, facilitating further heating by the subsequent molten - salt electro - heating systems; the (L + 1) - th to the Z - th continuous molten - salt electro - heating systems perform electro - heating on the molten salt, and their heating power control can precisely control the outlet molten - salt temperature, so that the finally stored molten salt reaches a predetermined temperature. The present invention ensures that the faulty heating unit can be bypassed at any time without affecting the operation of the heating array.

Description

Technical Field

[0001] The present invention relates to the field of energy storage, and particularly to an array molten salt electro-heating energy storage system. Background Art

[0002] The randomness, volatility and intermittency of new energy make it difficult to balance the power and energy of the power grid. The use of molten salt electro-heating energy storage technology can achieve the functions of power shifting and smoothing. However, the existing single molten salt electro-heater has a small power, which cannot meet the needs of new energy consumption and energy storage. Secondly, the existing molten salt electro-heater has poor flexibility. In existing projects, in order to ensure the safety of the molten salt temperature, the outlet temperature of the molten salt is reduced at the cost, which will affect the energy release efficiency of the molten salt energy storage system.

[0003] Chinese Patent CN 22 1570537 U discloses a high-power molten salt electro-heating system, including a hot salt tank, a cold salt tank and a molten salt conveying pipeline connecting the hot salt tank and the cold salt tank. One side of the molten salt conveying pipeline connected to the cold salt tank is the low-temperature section, and one side connected to the hot salt tank is the high-temperature section; the molten salt electro-heaters in its high-temperature section are in series, and the molten salt electro-heaters in the low-temperature section are in parallel to achieve high-power electro-heating of molten salt. However, it has not considered the problem of the temperature change of molten salt caused by the rapid response of the electro-heating to the electric power, and at the same time, it cannot achieve the low-power operation of the molten salt electro-heating.

[0004] Chinese Patent CN 1 15693728B discloses a photovoltaic direct-current electro-heating molten salt heat storage system and its heat storage method, including a photovoltaic power generation device, a direct-current transmission and transformation device and an electro-heating device. Its electro-heating device uses high, medium and low molten salt heaters in series. It has not solved the problems such as too high or too low temperature caused by molten salt electro-heating under the condition of rapid fluctuation of photovoltaic.

[0005] Chinese Patent CN 207350797U discloses a molten salt heating device, including a plurality of vertical molten salt heaters, and the molten salt heaters are connected in series or in parallel through pipelines. It can achieve high-power molten salt heating, but does not consider problems such as low-power operation of the heater and rapid response to power changes.

[0006] The existing molten salt electro-heating methods mainly focus on the power scale, but ignore the performance of the molten salt electro-heating methods in terms of the temperature quality of the heated molten salt, wide-condition operation and rapid response to the fluctuation of the electric power. At the same time, key problems such as the system not shutting down for maintenance and salt drainage in case of a failure of the molten salt electro-heater are not considered. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides an array molten salt electro-heating energy storage system, which is composed of the first, second, continuous to the Zth molten salt electro-heating systems and a buffer system, where Z is a positive integer greater than 1. Among them, the heating systems at different levels have different responses to fluctuating power and heat the molten salt to different temperatures. The first, second, continuous to the Lth molten salt electro-heating systems, where 1 ≤ L ≤ Z - 1, can quickly respond to new energy fluctuations within a large operating condition range, enabling it to follow the changes in new energy power, but there is also a certain fluctuation in the molten salt outlet temperature; the molten salt output from the first L levels of molten salt electro-heating systems enters the buffer system, facilitating further heating by the subsequent molten salt electro-heating systems; the (L + 1)th to Zth molten salt electro-heating systems electrically heat the molten salt, and their heating power control can precisely control the outlet molten salt temperature, so that the finally stored molten salt reaches a predetermined temperature. Among them, the first L levels of molten salt electro-heating systems can include one or more heating arrays, and the subsequent (Z - L) levels of molten salt electro-heating systems can also include one or more heating arrays, with a buffer system arranged between the heating arrays at different levels. The heating arrays are connected in series and parallel, and a fluid control valve and a salt discharge valve are configured for each heating unit to ensure that a faulty heating unit can be bypassed at any time without affecting the operation of the heating array.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An array molten salt electro-heating energy storage system, comprising the first, second to Zth molten salt electro-heating systems, a buffer system, a pump, a power supply and a control system, where Z is a positive integer greater than 1; the first, second to Lth molten salt electro-heating systems have the same structure and include a cold tank, a molten salt pipeline, a pump, and a coarse adjustment molten salt electro-heating array, where 1 ≤ L ≤ Z - 1; the buffer system includes a molten salt pipeline and a buffer container; the (L + 1)th to Zth molten salt electro-heating systems have the same structure and include a hot tank, a molten salt pipeline, a pump, and a fine adjustment molten salt electro-heating array; the power supply and control system includes a control module and a power supply module; the first, second to Lth molten salt electro-heating systems are connected in series in sequence, the Lth molten salt electro-heating system, the buffer system, the pump, and the (L + 1)th molten salt electro-heating system are connected in series in sequence through the molten salt pipeline, and the (L + 1)th to Zth molten salt electro-heating systems are connected in series in sequence.

[0010] Furthermore, the coarse adjustment molten salt electro-heating array in the first, second, continuous to the Lth molten salt electro-heating systems includes the first, second to Nth coarse adjustment molten salt electro-heater groups, where N is a positive integer greater than 1, and includes a molten salt bypass device and an interconnection device; the first, second to Nth coarse adjustment molten salt electro-heater groups are connected in series through the molten salt pipeline, and the first, second to Nth coarse adjustment molten salt electro-heater groups are arranged from high to low in the height difference direction.

[0011] Furthermore, the coarse adjustment molten salt electric heater group includes a first, second to Mth coarse adjustment self-locking molten salt electric heater group string, and is sequentially connected in parallel through the molten salt pipeline, M is a positive integer and greater than or equal to 1; the coarse adjustment self-locking molten salt electric heater group string includes a first, second to Pth coarse adjustment self-locking molten salt electric heater, wherein all coarse adjustment self-locking molten salt electric heaters are connected in series, P is a positive integer and greater than or equal to 1;

[0012] The coarse adjustment self-locking molten salt electric heater includes a first self-locking molten salt valve, a second self-locking molten salt valve, a salt discharge valve, a coarse adjustment molten salt electric heater and a temperature sensor, wherein the first self-locking molten salt valve, the coarse adjustment molten salt electric heater and the second self-locking molten salt valve are sequentially connected in series through a molten salt pipeline, and a temperature sensor is arranged after the second self-locking molten salt valve, and one end of the salt discharge valve is connected in parallel with the outlet of the coarse adjustment molten salt electric heater.

[0013] Furthermore, the interconnection device includes an interconnected molten salt valve, wherein the outlets of the first, second to pth coarse adjustment self-locking molten salt electric heaters in the mth group of coarse adjustment molten salt electric heaters are interconnected with the outlets of the first, second to pth coarse adjustment self-locking molten salt electric heaters in the m+1th coarse adjustment molten salt electric heater through the interconnected molten salt valve, wherein 1≤m≤M-1.

[0014] Furthermore, the molten salt bypass device includes a first molten salt valve, a second molten salt valve, a bypass molten salt valve, a bypass molten salt pipeline and a temperature sensor. The first molten salt valve and the second molten salt valve are connected in series in sequence through the bypass molten salt pipeline, and the bypass molten salt valve is connected in parallel with the outlets of the first, second to P-1 coarse adjustment self-locking molten salt electric heaters in all the coarse adjustment molten salt electric heater strings between the bypass molten salt pipeline sections determined by the series connection of the first and second molten salt valves, and a temperature sensor is arranged at the far end of the parallel point along the process.

[0015] Furthermore, the coarse-adjustment molten salt electric heater includes a molten salt cylinder, first, second, and continuous to Xth electric heating tubes, a junction box, a flange, a molten salt inlet, a molten salt outlet, a temperature sensor and a baffle; the electric heating tube is a U-shaped electric heating tube or a cylindrical electric heating tube; the first, second to Xth electric heating tubes are all inserted in the flange and the baffle, and are dispersedly arranged in the molten salt cylinder, and the flange and the baffle provide support for the electric heating tube; wherein the first, second to Xth electric heating tubes are connected in series through wires in the junction box; the baffles are evenly distributed on the molten salt electric heater process, and the molten salt inlet and outlet are located at the horizontal upper and lower ends of the molten salt cylinder respectively; the temperature sensor is located at the baffle.

[0016] Furthermore, the buffer container of the buffer system is at least one buffer tank or at least one pipe with a diameter larger than the connected molten salt pipe, or a series combination of a buffer tank and a large-diameter molten salt pipe.

[0017] Further, the fine-tuning molten salt electric heating array is formed by replacing at least one and at most P coarse-tuning self-locking molten salt electric heaters in the string formed by all the coarse-tuning molten salt electric heaters in the coarse-tuning molten salt electric heating array with fine-tuning self-locking molten salt electric heaters; the fine-tuning self-locking molten salt electric heater includes a first self-locking molten salt valve, a second self-locking molten salt valve, a salt discharging valve, a fine-tuning molten salt electric heater, and a temperature sensor. Among them, the first self-locking molten salt valve, the fine-tuning molten salt electric heater, and the second self-locking molten salt valve are sequentially connected in series through a molten salt pipeline, and a temperature sensor is arranged behind the second self-locking molten salt valve. One end of the salt discharging valve is connected in parallel with the outlet of the coarse-tuning molten salt electric heater; the fine-tuning molten salt electric heater is a horizontal fine-tuning molten salt electric heater or a vertical fine-tuning molten salt electric heater, and the horizontal and vertical directions are defined according to whether the arrangement direction of the electric heating groups in the electric heater is the same as or perpendicular to the fluid flow direction.

[0018] Further, the horizontal fine-tuning molten salt electric heater includes a molten salt cylinder, the first, second, continuous to the i-th electric heating tubes, a wire collecting box, a flange, a molten salt inlet, a molten salt outlet, and a support bar, where i is a positive integer greater than or equal to 1. The electric heating tubes can be U-shaped electric heating tubes or cylindrical electric heating tubes. The first, second, continuous to the i-th electric heating tubes are all inserted on the flange and are arranged in a matrix and dispersed in the molten salt cylinder. The flange and the support bar provide support for the electric heating tubes, and the support bar is a thin-diameter steel bar. Among them, the electric heating tubes at the same horizontal plane in the molten salt cylinder are connected in series by wires in the wire collecting box to form a horizontal electric heating tube group, and mechanical support is provided between the horizontal electric heating tube groups and between the horizontal electric heating tube groups and the molten salt cylinder by the support bar. The molten salt inlet and outlet are respectively located at the upper and lower ends of the molten salt cylinder in the horizontal direction.

[0019] Further, the vertical fine-tuning molten salt electric heater includes a molten salt cylinder, the first, second to the Q vertical electric heating groups, a molten salt inlet, and a molten salt outlet, where Q is a positive integer greater than or equal to 1; the molten salt flows into the molten salt cylinder from the molten salt inlet and contacts the first, second to the Q vertical electric heating groups and then flows out from the molten salt outlet; the first, second to the Q vertical electric heating groups are arranged perpendicular to the molten salt cylinder. The vertical electric heating group includes a wire collecting box, the first, second to the i-th electric heating tubes, a flange, and a support bar; the first, second to the i-th electric heating tubes are all inserted on the flange, and the flange and the support bar provide support for the electric heating tubes.

[0020] Further, the control module obtains real-time fluctuation data of new energy through a power measurement sensor, calculates the required power, flow rate, and the opening degrees of each valve for the coarse and fine adjustment molten salt electroheating systems, and issues this instruction to the power supply module, pumps, and valves for execution; the power supply module is connected to the coarse and fine adjustment molten salt electroheaters; the power supply module is a plurality of reverse-parallel thyristor circuits or a plurality of converters. The reverse-parallel thyristor circuit includes at least two thyristors connected in parallel in opposite directions; if the power supply module is a reverse-parallel thyristor circuit, one end of it is connected to the high-voltage grid bus. When connected to the coarse adjustment molten salt electroheater, the other end is connected to the two ends formed by the series connection of the electric heating tubes in the coarse adjustment molten salt electroheater; when connected to the fine adjustment molten salt electroheater, the power supply module is connected to the two ends of the horizontal electric heating tube group in the horizontal fine adjustment molten salt electroheater or is respectively connected to the vertical electric heating groups in the vertical fine adjustment molten salt electroheater; the converter includes first, second to Y AC / DC / DC converters, and their output ports are connected in series or in parallel; each AC / DC / DC converter includes a transformer, an AC / DC module, a voltage stabilizing capacitor, and a DC / DC module; the positive pole formed by the output port of the AC / DC module is connected to the positive pole of the voltage stabilizing capacitor, and the positive pole of the voltage stabilizing capacitor is connected to the positive input port of the DC / DC module; the negative pole formed by the output port of the AC / DC module is connected to the negative pole of the voltage stabilizing capacitor, and the negative pole of the voltage stabilizing capacitor is connected to the negative input port of the DC / DC module.

[0021] Beneficial effects:

[0022] 1. In the present invention, the electric heaters are arranged in an array, enabling high-power deployment operation of molten salt electroheating.

[0023] 2. In the present invention, the coarse adjustment molten salt electroheating system and the fine adjustment molten salt electroheating system can absorb the fluctuating power of new energy within a large operating condition range.

[0024] 3. In the present invention, the coarse adjustment molten salt electroheating system can quickly respond to the power fluctuation of new energy.

[0025] 4. In the present invention, the buffer system and the fine adjustment molten salt electroheating system can ensure a constant outlet temperature of molten salt electroheating. Description of the drawings

[0026] Figure 1 Schematic diagram of an array molten salt electroheating system according to Embodiment 1 of the present invention;

[0027] Figure 2 Schematic diagram of a molten salt interconnection device that can be used in Embodiment 1 of the present invention;

[0028] Figure 3 Schematic diagram of the structure of the coarse adjustment molten salt electroheater used in Embodiment 1 of the present invention;

[0029] Figure 4Schematic diagram of the lateral fine-tuning molten salt electric heater used in Embodiment 1 of the present invention;

[0030] Figure 5 Schematic diagram of the longitudinal fine-tuning molten salt electric heater used in Embodiment 1 of the present invention;

[0031] Figure 6 Schematic diagram of the thyristor antiparallel circuit provided by Embodiment 1 of the present invention;

[0032] Figure 7 Schematic diagram of the current conversion device provided by Embodiment 1 of the present invention.

[0033] Among them, the reference numerals are: 1001 - cold tank, 1002 - pump, 1003 - molten salt pipeline, 1004-1 - first molten salt valve, 1004-2 - second molten salt valve, 1005-1 - first self-locking molten salt valve, 1005-2 - second self-locking molten salt valve, 1006 - interconnection molten salt valve, 1007 - bypass molten salt valve, 1008 - coarse-tuning molten salt electric heater, 1009 - first temperature sensor, 1010 - bypass molten salt pipeline, 1011 - coarse-tuning self-locking molten salt electric heater, 1012 - salt discharge valve, 2001 - buffer tank, 3001 - fine-tuning self-locking molten salt electric heater, 3003 - fine-tuning molten salt electric heater, 3002 - hot tank, 1008-1 molten salt cylinder, 1008-2 electric heating tube, 1008-3 wire collecting box, 1008-4 flange, 1008-5 molten salt inlet, 1008-6 molten salt outlet, 1008-7 baffle plate, 1008-8 second temperature sensor, 1008-9 support bar, 1008-10 horizontal electric heating tube group, 4001 - thyristor, 4002 - high-voltage power grid busbar, 4003 - transformer, 4004 - AC / DC module, 4005 - voltage stabilizing capacitor, 4007 - DC / DC module, 4006-1 - first AC / DC / DC converter, 4006-Y - the Yth AC / DC / DC converter. Detailed implementation manners

[0034] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] As Figure 1As shown in the figure, an array molten salt electro-heating energy storage system according to Embodiment 1 of the present invention includes a first molten salt electro-heating system, a second molten salt electro-heating system, a buffer system, a pump 1002, a power supply and a control system. The first molten salt electro-heating system includes a cold tank 1001, a molten salt pipeline 1003, a pump 1002, and a coarse-adjustment molten salt electro-heating array; the buffer system includes a molten salt pipeline 1003 and a buffer container; the second molten salt electro-heating system includes a hot tank 3002, a molten salt pipeline 1003, a pump 1002, and a fine-adjustment molten salt electro-heating array; the power supply and the control system include a control module and a power supply module. The first molten salt electro-heating system, the buffer system, the pump 1002, and the second molten salt electro-heating system are connected in series in sequence through the molten salt pipeline.

[0036] Further, the coarse-adjustment molten salt electro-heating array includes first, second to Nth coarse-adjustment molten salt electro-heater groups, and the coarse-adjustment molten salt electro-heater group refers to Figure 1 a group formed by a branch with 3 in series and then paralleled with two other loops with 3 in series. N is a positive integer greater than 1, and it may further include a molten salt bypass device and an interconnection device. The first, second to Nth coarse-adjustment molten salt electro-heater groups are connected in series through the molten salt pipeline 1003, and the first, second to Nth coarse-adjustment molten salt electro-heater groups are arranged from high to low in the horizontal height difference direction.

[0037] The coarse-adjustment molten salt electro-heater group includes first, second to Mth coarse-adjustment self-locking molten salt electro-heater group strings, and the first, second to Mth coarse-adjustment self-locking molten salt electro-heater group strings are connected in parallel in sequence through the molten salt pipeline 1003. M is a positive integer greater than or equal to 1. The coarse-adjustment self-locking molten salt electro-heater group string includes first, second to Pth coarse-adjustment self-locking molten salt electro-heaters 1011, where all the coarse-adjustment self-locking molten salt electro-heaters 1011 are connected in series. P is a positive integer greater than or equal to 1. The coarse-adjustment self-locking molten salt electro-heater 1011 includes a first self-locking molten salt valve 1005-1, a second self-locking molten salt valve 1005-2, a salt discharge valve 1012, a coarse-adjustment molten salt electro-heater 1008, and a first temperature sensor 1009. Among them, the first self-locking molten salt valve 1005-1, the coarse-adjustment molten salt electro-heater 1008, and the second self-locking molten salt valve 1005-2 are connected in series in sequence through the molten salt pipeline 1003. At the same time, a first temperature sensor 1009 is arranged behind the second self-locking molten salt valve 1005-2, and one end of the salt discharge valve 1012 is connected in parallel with the outlet of the coarse-adjustment molten salt electro-heater 1008.

[0038] As Figure 2As shown, the interconnection device includes an interconnected molten salt valve 1006, wherein the outlets of the first, second to pth coarse adjustment self-locking molten salt electric heaters 1011 in the mth group of coarse adjustment molten salt electric heaters are interconnected with the outlets of the first, second to pth coarse adjustment self-locking molten salt electric heaters 1011 in the m+1th coarse adjustment molten salt electric heater string through the interconnected molten salt valve 1006, wherein 1≤m≤M-1, 1≤p≤P.

[0039] The molten salt bypass device includes a first molten salt valve 1004-1, a second molten salt valve 1004-2, a bypass molten salt valve 1007, a bypass molten salt pipeline 1010 and a first temperature sensor 1009. The first molten salt valve 1004-1 and the second molten salt valve 1004-2 are connected in series in sequence through the bypass molten salt pipeline 1010, and the bypass molten salt valve 1007 is connected in parallel with the outlets of the first, second to P-1 coarse adjustment self-locking molten salt electric heaters 1011 in all the coarse adjustment molten salt electric heater strings in the bypass molten salt pipeline 1010 section determined by the series connection of the first molten salt valve 1004-1 and the second molten salt valve 1004-2, and the first temperature sensor 1009 is set at the far end of the parallel point along the process.

[0040] like Figure 3 As shown, the coarse-adjustment molten salt electric heater 1008 includes a molten salt cylinder 1008-1, first, second, and Xth electric heating pipes 1008-2, a junction box 1008-3, a flange 1008-4, a molten salt inlet 1008-5, a molten salt outlet 1008-6, a temperature sensor 1008-8, and a baffle 1008-7. The electric heating pipes 1008-2 can be U-shaped or cylindrical. The first, second, and Xth electric heating pipes 1008-2 are interspersed through the flange 1008-4 and baffle 1008-7, and are dispersedly arranged within the molten salt cylinder 1008-1. The flange 1008-4 and baffle 1008-7 provide support for the electric heating pipes 1008-2. The first, second, through Xth electric heating tubes 1008-2 are connected in series via wires in a junction box 1008-3. Baffles 1008-7 are evenly distributed along the flow path of the molten salt cylinder 1008-1. The molten salt inlet 1008-5 and outlet 1008-6 are located at the horizontal upper and lower ends of the molten salt cylinder 1008-1, respectively. A second temperature sensor 1008-8 is located on the baffle 1008-7.

[0041] Furthermore, the buffer container of the buffer system is a buffer tank 2001.

[0042] Furthermore, the fine-tuning molten salt electric heating array replaces at least one and at most P coarse-tuning self-locking molten salt electric heaters 1011 in all the coarse-tuning molten salt electric heater groups in the coarse-tuning molten salt electric heating array with a fine-tuning self-locking molten salt electric heater 3003. The fine-tuning self-locking molten salt electric heater 3001 includes a first self-locking molten salt valve 1005-1, a second self-locking molten salt valve 1005-2, a salt discharge valve 1012, a fine-tuning molten salt electric heater 3003, and a first temperature sensor 1009. The first self-locking molten salt valve 1005-1, the fine-tuning molten salt electric heater 3003, and the second self-locking molten salt valve 1005-2 are sequentially connected in series through a molten salt pipeline 1003. The first temperature sensor 1009 is disposed after the second self-locking molten salt valve 1005-2. One end of the salt discharge valve 1012 is connected in parallel to the outlet of the coarse-tuning molten salt electric heater 1008. The fine-tuning molten salt electric heater 3003 can be a horizontal fine-tuning molten salt electric heater or a vertical fine-tuning molten salt electric heater.

[0043] like Figure 4 As shown, the fine-tuning molten salt electric heater includes a horizontal fine-tuning molten salt electric heater and a vertical fine-tuning molten salt electric heater. The horizontal and vertical directions are defined by the arrangement of the heating elements in the heater in the same direction as or perpendicular to the fluid flow direction. The horizontal fine-tuning molten salt electric heater includes a molten salt cylinder 1008-1, the first, second, through i-th heating tubes 1008-2, a junction box 1008-3, a flange 1008-4, a molten salt inlet 1008-5, a molten salt outlet 1008-6, and a brace 1008-9, where i is a positive integer greater than or equal to 1. The heating tubes 1008-2 can be U-shaped or cylindrical. The first, second, through the i-th electric heating tubes 1008-2 are inserted through flange 1008-4 and arranged in a matrix within molten salt cylinder 1008-1. Flange 1008-4 and support bars 1008-9, made of thin steel bars, provide support for the electric heating tubes 1008-2. Electric heating tubes 1008-2 on the same horizontal plane within the molten salt cylinder are connected in series via wires in junction box 1008-3 to form horizontal electric heating tube group 1008-10. Support bars 1008-9 provide mechanical support between the horizontal electric heating tube groups and between the horizontal electric heating tube group 1008-10 and the molten salt cylinder 1008-1. The molten salt inlet 1008-5 and outlet 1008-6 are located at the horizontal upper and lower ends of the molten salt cylinder 1008-1, respectively.

[0044] like Figure 5As shown, the longitudinal fine-tuning molten salt electric heater includes a molten salt cylinder 1008-1, first, second to Q vertical electric heating groups, a molten salt inlet 1008-5 and a molten salt outlet 1008-6, where Q is a positive integer greater than or equal to 1. Molten salt flows into the molten salt cylinder 1008-1 from the molten salt inlet 1008-5, contacts the first, second to Q vertical electric heating groups, and flows out from the molten salt outlet 1008-6. The first, second to Q vertical electric heating groups are vertically arranged with respect to the molten salt cylinder 1008-1. The vertical electric heating group includes a wire collecting box 1008-3, first, second to the i-th electric heating tubes 1008-2, a flange 1008-4 and a support bar 1008-9. The electric heating tube 1008-2 can be a U-shaped electric heating tube or a cylindrical electric heating tube. The first, second to the i-th electric heating tubes are all inserted through the flange 1008-4, and the flange 1008-4 and the support bar 1008-9 provide support for the electric heating tube 1008-2. Preferably, the support bar 1008-9 is a thin-diameter steel bar.

[0045] As Figure 6 As shown, the control module obtains the real-time fluctuation data of new energy through a power measurement sensor, calculates the required power, flow rate and the opening degrees of each valve for the coarse-tuning molten salt electric heating system and the fine-tuning molten salt electric heating system, and issues this instruction to the power supply module, the pump and the valve for execution. The power supply module is connected to the coarse-tuning molten salt electric heating system and the fine-tuning molten salt electric heater. The power supply module can be a plurality of thyristor anti-parallel circuits or a plurality of current conversion devices. The thyristor anti-parallel circuit includes at least two thyristors 4001 connected in parallel in opposite directions. If the power supply module is a thyristor anti-parallel circuit, one end of it is connected to the high-voltage grid bus 4002. When connecting to the coarse-tuning molten salt electric heater 1008, the other end is connected to the two ends formed by being connected in series with the electric heating tube 1008-2 in the coarse-tuning molten salt electric heater 1008. When connecting to the fine-tuning molten salt electric heater 3003, the power supply module is connected to the two ends of the horizontal electric heating tube group 1008-10 in the fine-tuning molten salt electric heater 3003 or is respectively connected to the vertical electric heating groups in the longitudinal fine-tuning molten salt electric heater.

[0046] As Figure 7As shown, the converter device includes a first AC / DC / DC converter 4006-1, a second AC / DC / DC converter to a Y-th AC / DC / DC converter 4006-Y, and their output ports are connected in series or in parallel. Further, each AC / DC / DC converter includes a transformer 4003, an AC / DC module 4004, a voltage stabilizing capacitor 4005, and a DC / DC module 4007. Among them, the positive pole formed by the output port of the AC / DC module 4004 is connected to the positive pole of the voltage stabilizing capacitor 4005, and the positive pole of the voltage stabilizing capacitor 4005 is connected to the positive input port of the DC / DC module 4007; the negative pole formed by the output port of the AC / DC module 4004 is connected to the negative pole of the voltage stabilizing capacitor 4005, and the negative pole of the voltage stabilizing capacitor 4005 is connected to the negative input port of the DC / DC module 4007. Among them, the AC / DC module 4004 is preferably a three-phase diode uncontrolled rectifier circuit, a three-phase thyristor phase-controlled rectifier circuit, or a three-phase IGBT PWM rectifier circuit; the DC / DC module 4007 is preferably a Buck circuit, a Boost circuit, or a Buck-Boost circuit.

[0047] So far, the technical route of the present invention has been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An array molten salt electrothermal energy storage system, characterized in that, It includes the first, second to Zth molten salt electric heating systems, a buffer system, pumps, a power supply and a control system, where Z is a positive integer greater than 1; the first, second to Lth molten salt electric heating systems have the same structure, including a cold tank, molten salt pipelines, pumps, and a coarse-adjustment molten salt electric heating array, where 1 ≤ L ≤ Z - 1; the buffer system includes molten salt pipelines and a buffer container; the (L + 1)th to Zth molten salt electric heating systems have the same structure, including a hot tank, molten salt pipelines, pumps, and a fine-adjustment molten salt electric heating array; the power supply and control system includes a control module and a power supply module; the first, second to Lth molten salt electric heating systems are connected in series in sequence, the Lth molten salt electric heating system, the buffer system, the pumps, and the (L + 1)th molten salt electric heating system are connected in series in sequence through molten salt pipelines, and the (L + 1)th to Zth molten salt electric heating systems are connected in series in sequence. The coarse-adjustment molten salt electric heating array in the first, second, continuously to Lth molten salt electric heating systems includes the first, second to Nth coarse-adjustment molten salt electric heater groups, where N is a positive integer greater than 1, and includes a molten salt bypass device and an interconnection device; the first, second to Nth coarse-adjustment molten salt electric heater groups are connected in series through molten salt pipelines, and the first, second to Nth coarse-adjustment molten salt electric heater groups are arranged from high to low in the height difference direction. The molten salt bypass device includes a first molten salt valve, a second molten salt valve, a bypass molten salt valve, a bypass molten salt pipeline, and a temperature sensor. The first molten salt valve and the second molten salt valve are connected in series through the bypass molten salt pipeline in sequence, and between the bypass molten salt pipeline segments determined by the series connection of the first and second molten salt valves, through the bypass molten salt valve, it is connected in parallel with the outlets of the first, second to (P - 1)th coarse-adjustment self-locking molten salt electric heaters in all the coarse-adjustment molten salt electric heater groups in series, and a temperature sensor is arranged at the far end along the process at the parallel connection point.

2. The array molten salt electrothermal energy storage system according to claim 1, characterized in that The coarse-adjustment molten salt electric heater group includes the first, second to Mth coarse-adjustment self-locking molten salt electric heater groups in series, and are connected in parallel through molten salt pipelines in sequence, where M is a positive integer greater than or equal to 1; the coarse-adjustment self-locking molten salt electric heater groups in series include the first, second to Pth coarse-adjustment self-locking molten salt electric heaters, where all the coarse-adjustment self-locking molten salt electric heaters are connected in series, and P is a positive integer greater than or equal to 1. The coarse-adjustment self-locking molten salt electric heater includes a first self-locking molten salt valve, a second self-locking molten salt valve, a salt discharge valve, a coarse-adjustment molten salt electric heater, and a temperature sensor. Among them, the first self-locking molten salt valve, the coarse-adjustment molten salt electric heater, and the second self-locking molten salt valve are connected in series through molten salt pipelines in sequence, and a temperature sensor is arranged behind the second self-locking molten salt valve, and one end of the salt discharge valve is connected in parallel with the outlet of the coarse-adjustment molten salt electric heater.

3. The array molten salt electrothermal energy storage system according to claim 2, wherein The interconnection device includes an interconnection molten salt valve. Among them, the outlets of the first, second to pth coarse-adjustment self-locking molten salt electric heaters in the mth group of coarse-adjustment molten salt electric heaters are interconnected with the outlets of the first, second to pth coarse-adjustment self-locking molten salt electric heaters in the (m + 1)th coarse-adjustment molten salt electric heater through the interconnection molten salt valve, where 1 ≤ m ≤ M - 1, and M is the number of the coarse-adjustment self-locking molten salt electric heater groups in series.

4. An array molten salt electrothermal energy storage system according to claim 2, characterized in that, The coarse - tuning molten salt electro - heater includes a molten salt cylinder, first, second, continuous to the Xth electric heating tubes, a wire - collecting box, a flange, a molten salt inlet, a molten salt outlet, a temperature sensor, and a baffle plate; the electric heating tubes are U - shaped electric heating tubes or cylindrical electric heating tubes; the first, second to the Xth electric heating tubes are all inserted through the flange and the baffle plate, and are dispersedly arranged in the molten salt cylinder. The flange and the baffle plate provide support for the electric heating tubes; among them, the first, second to the Xth electric heating tubes are connected in series by wires in the wire - collecting box; the baffle plates are evenly distributed on the flow path of the molten salt electro - heater, and the molten salt inlet and outlet are respectively located at the upper and lower horizontal ends of the molten salt cylinder; the temperature sensor is located at the baffle plate.

5. The array molten salt electrothermal energy storage system according to claim 1, wherein The buffer container of the buffer system is at least one buffer tank or at least one pipe with a diameter larger than the connected molten salt pipeline or a series combination of a buffer tank and a large - diameter molten salt pipeline.

6. The array molten salt electrothermal energy storage system according to claim 2, wherein The fine - tuning molten salt electro - heating array is formed by replacing at least one and at most P coarse - tuning self - locking molten salt electro - heaters in the string composed of all the coarse - tuning molten salt electro - heaters in the coarse - tuning molten salt electro - heating array with fine - tuning self - locking molten salt electro - heaters; the fine - tuning self - locking molten salt electro - heater includes a first self - locking molten salt valve, a second self - locking molten salt valve, a salt - discharging valve, a fine - tuning molten salt electro - heater, and a temperature sensor. Among them, the first self - locking molten salt valve, the fine - tuning molten salt electro - heater, and the second self - locking molten salt valve are connected in series through a molten salt pipeline in sequence. At the same time, a temperature sensor is arranged behind the second self - locking molten salt valve, and one end of the salt - discharging valve is connected in parallel with the outlet of the coarse - tuning molten salt electro - heater; the fine - tuning molten salt electro - heater is a horizontally fine - tuning molten salt electro - heater or a vertically fine - tuning molten salt electro - heater, and the horizontal and vertical directions are defined according to whether the arrangement direction of the electric heating groups in the electro - heater is the same as or perpendicular to the fluid flow direction.

7. The array molten salt electrothermal energy storage system according to claim 6, characterized in that, The horizontally fine - tuning molten salt electro - heater includes a molten salt cylinder, first, second, continuous to the ith electric heating tubes, a wire - collecting box, a flange, a molten salt inlet, a molten salt outlet, and a support bar, where i is a positive integer and i≥1; the electric heating tubes are U - shaped electric heating tubes or cylindrical electric heating tubes; The first, second, continuous to the ith electric heating tubes are all inserted through the flange and are arranged in a matrix - like and dispersed manner in the molten salt cylinder. The flange and the support bar provide support for the electric heating tubes, and the support bar is a thin - diameter steel bar; among them, the electric heating tubes at the same horizontal plane in the molten salt cylinder are connected in series by wires in the wire - collecting box to form a horizontal electric heating tube group. Mechanical support is provided between the horizontal electric heating tube groups and between the horizontal electric heating tube groups and the molten salt cylinder by the support bar; where the molten salt inlet and outlet are respectively located at the upper and lower horizontal ends of the molten salt cylinder.

8. An array molten salt electrothermal energy storage system according to claim 7, characterized in that, The vertically fine - tuning molten salt electro - heater includes a molten salt cylinder, first, second to the Qth vertical electric heating groups, a molten salt inlet, and a molten salt outlet, where Q is a positive integer and Q≥1; the molten salt flows into the molten salt cylinder from the molten salt inlet and contacts the first, second to the Qth vertical electric heating groups, and then flows out from the molten salt outlet; the first, second to the Qth vertical electric heating groups are arranged perpendicular to the molten salt cylinder; the vertical electric heating group includes a wire - collecting box, first, second to the ith electric heating tubes, a flange, and a support bar; the first, second to the ith electric heating tubes are all inserted through the flange, and the flange and the support bar provide support for the electric heating tubes.

9. The array molten salt electrothermal energy storage system according to claim 1, wherein The control module obtains real-time fluctuation data of new energy through a power measurement sensor, calculates the required power, flow rate, and the opening degrees of each valve for the coarse and fine-tuning molten salt electric heating arrays, and issues instructions to the power supply module, pumps, and valves for execution; the power supply module is connected to the coarse and fine-tuning molten salt electric heaters; the power supply module is a plurality of reverse-parallel thyristor circuits or a plurality of variable current devices, and the reverse-parallel thyristor circuit includes at least two thyristors connected in parallel in opposite directions; if the power supply module is a reverse-parallel thyristor circuit, one end of it is connected to the high-voltage grid busbar, and when connected to the coarse-tuning molten salt electric heater, the other end is connected to the two ends formed by the series connection of the electric heating tubes in the coarse-tuning molten salt electric heater; when connected to the fine-tuning molten salt electric heater, the power supply module is connected to the two ends of the horizontal electric heating tube group in the horizontal fine-tuning molten salt electric heater or is respectively connected to the vertical electric heating groups in the vertical fine-tuning molten salt electric heater; the variable current device includes first, second to Y AC / DC / DC converters, and their output ports are connected in series or in parallel; each AC / DC / DC converter includes a transformer, an AC / DC module, a voltage stabilizing capacitor, and a DC / DC module; the positive pole formed by the output port of the AC / DC module is connected to the positive pole of the voltage stabilizing capacitor, and the positive pole of the voltage stabilizing capacitor is connected to the positive input port of the DC / DC module; the negative pole formed by the output port of the AC / DC module is connected to the negative pole of the voltage stabilizing capacitor, and the negative pole of the voltage stabilizing capacitor is connected to the negative input port of the DC / DC module.

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