Array fused salt electric heating energy storage system

Abstract

The invention relates to an array fused salt electric heating energy storage system which comprises a first fused salt electric heating system, a second fused salt electric heating system, a third fused salt electric heating system, a fourth fused salt electric heating system, a fifth fused salt electric heating system and a sixth fused salt electric heating system. Wherein different stages of heating systems have different responses to fluctuating power, and the fused salt is heated to different temperatures. L is greater than or equal to 1 and less than or equal to Z-1, new energy fluctuation can be quickly responded in a relatively large working condition, the new energy fluctuation can be changed along with new energy power, but the temperature of a fused salt outlet also has certain fluctuation; fused salt output by the front L-stage fused salt electric heating systems enters the buffer system, so that the fused salt can be further heated by the rear-stage fused salt electric heating system; the fused salt is electrically heated by the (L + 1) th, (L + 1) th, (L + 1) th, (L + 1) th, (Z) th fused salt electric adding systems, and the temperature of outlet fused salt can be accurately controlled through heating power control, so that the finally stored fused salt reaches a preset temperature. The invention ensures that the faulty heating unit is bypassed at any time without affecting the operation of the heating array.

Description

Technical Field

[0001] This invention relates to the field of energy storage, and more specifically to an array molten salt electric heating energy storage system. Background Technology

[0002] The randomness, volatility, and intermittency of new energy sources make it difficult to balance power and energy in the power grid. Molten salt electric heating energy storage technology can achieve power shifting and smoothing. However, the power of existing molten salt electric heaters is relatively small, which cannot meet the needs of new energy consumption and energy storage. Secondly, existing molten salt electric heaters have poor flexibility. Some projects have sacrificed the molten salt outlet temperature to ensure the safety of the molten salt temperature, 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 electric heating system, including a hot salt tank, a cold salt tank, and a molten salt conveying pipeline connecting the hot and cold salt tanks. The side of the molten salt conveying pipeline connected to the cold salt tank is a low-temperature section, and the side connected to the hot salt tank is a high-temperature section. The high-temperature section molten salt electric heaters are connected in series, and the low-temperature section molten salt electric heaters are connected in parallel to achieve high-power electric heating of molten salt. However, it does not consider the problem of molten salt temperature changes caused by the rapid response of electric heating power, and it cannot achieve low-power operation of molten salt electric heating.

[0004] Chinese patent CN 1 15693728B discloses a photovoltaic DC electric heating molten salt thermal storage system and its thermal storage method, including a photovoltaic power generation device, a DC transmission and transformation device, and an electric heating device. The electric heating device uses high, medium, and low molten salt heaters connected in series. However, it does not solve the problems of excessively high or low temperatures caused by molten salt electric heating under rapidly fluctuating photovoltaic conditions.

[0005] Chinese patent CN 207350797U discloses a molten salt heating device, comprising several vertical molten salt heaters connected in series or parallel via pipelines. It can achieve high-power molten salt heating, but does not address issues such as low-power operation of the heaters and rapid response to power changes.

[0006] Existing molten salt electric heating methods primarily focus on power output, neglecting aspects such as the quality of molten salt heating temperature, wide operating range, and rapid response to power fluctuations. Furthermore, they fail to consider critical issues such as uninterrupted system maintenance in case of molten salt heater failure and salt removal. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides an array molten salt electric heating energy storage system, comprising a first, second, and Z-th continuous molten salt electric heating system and a buffer system, where Z is a positive integer greater than 1. The different stages of the heating system respond differently to power fluctuations and heat the molten salt to different temperatures. The first, second, and L-th continuous molten salt electric heating systems, 1≤L≤Z-1, can quickly respond to new energy fluctuations within a wide operating range, allowing them to follow changes in new energy power, although the molten salt outlet temperature also fluctuates somewhat. The molten salt output from the first L-th stage of the molten salt electric heating system enters the buffer system, facilitating further heating by subsequent stages. The L+1-th and Z-th continuous molten salt electric heating systems electrically heat the molten salt, and their heating power control can precisely control the outlet molten salt temperature, ensuring that the finally stored molten salt reaches a predetermined temperature. The first L-th stage of the molten salt electric heating system may include one or more heating arrays, and the subsequent ZL-th stage of the molten salt electric heating system may also include one or more heating arrays, with a buffer system positioned between the different stages of the heating arrays. The heating array uses a series-parallel connection, and each heating unit is equipped with a fluid control valve and a salt drain valve 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 objectives, the present invention adopts the following technical solution:

[0009] An array molten salt electric heating energy storage system includes first, second to Zth molten salt electric 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 electric heating systems have the same structure, including a cold tank, molten salt pipelines, a pump, 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+1th to Zth molten salt electric heating systems have the same structure, including a hot tank, molten salt pipelines, a pump, 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, the Lth molten salt electric heating system, the buffer system, the pump, and the L+1th molten salt electric heating system are connected in series via molten salt pipelines, and the L+1th to Zth molten salt electric heating systems are connected in series.

[0010] Furthermore, the coarse-adjustment molten salt electric heating array in the first, second, and Lth molten salt electric heating systems includes 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 pipes, and the first, second to Nth coarse-adjustment molten salt electric heater groups are arranged from high to low in the direction of elevation difference.

[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, which are connected in parallel sequentially through molten salt pipes, where 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, where 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 drain valve, a coarse-adjustment molten salt electric heater, and a temperature sensor. 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 a molten salt pipeline. A temperature sensor is installed after the second self-locking molten salt valve. One end of the salt drain valve is connected in parallel with the outlet of the coarse-adjustment molten salt electric heater.

[0013] Furthermore, the interconnection device includes an interconnection 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+1)th group of coarse-adjustment molten salt electric heaters via the interconnection molten salt valve, where 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 through the bypass molten salt pipeline. Between the bypass molten salt pipeline sections determined by the series connection of the first and second molten salt valves, the bypass molten salt valves are connected in parallel to the outlets of the first, second to P-1 coarse-adjustment self-locking molten salt electric heaters in all coarse-adjustment molten salt electric heater strings. A temperature sensor is installed at the far end of the process along the parallel connection point.

[0015] Furthermore, the coarse-adjustment molten salt electric heater includes a molten salt cylinder, first, second, and Xth heating elements, a junction box, a flange, a molten salt inlet, a molten salt outlet, a temperature sensor, and baffles; the heating elements are U-shaped or cylindrical; the first, second, and Xth heating elements are all inserted through the flange and baffles, and are distributed dispersedly within the molten salt cylinder, with the flange and baffles providing support for the heating elements; wherein, the first, second, and Xth heating elements are connected in series by wires in the junction box; the baffles are evenly distributed along the flow path of the molten salt electric heater, with the molten salt inlet and outlet located at the upper and lower horizontal ends of the molten salt cylinder, respectively; the temperature sensor is located at the baffles.

[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 that of the connected molten salt pipe, or a series combination of a buffer tank and a large-diameter molten salt pipe.

[0017] Furthermore, 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 of all 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 drain valve, a fine-tuning molten salt electric heater, and a temperature sensor. The first self-locking molten salt valve, the fine-tuning molten salt electric heater, and the second self-locking molten salt valve are connected in series through molten salt pipes. A temperature sensor is installed after the second self-locking molten salt valve. One end of the salt drain valve is connected in parallel to the outlet of the coarse-tuning molten salt electric heater. The fine-tuning molten salt electric heater is either a horizontal fine-tuning molten salt electric heater or a vertical fine-tuning molten salt electric heater. The horizontal and vertical directions are defined according to whether the arrangement direction of the electric heating elements in the electric heater is the same as or perpendicular to the fluid flow direction.

[0018] Furthermore, the horizontally adjustable molten salt electric heater includes a molten salt cylinder, first, second, and i-th consecutive heating tubes, a junction box, a flange, a molten salt inlet, a molten salt outlet, and support bars, where i is a positive integer greater than or equal to 1. The heating tubes can be U-shaped or cylindrical. The first, second, and i-th consecutive heating tubes are all inserted onto the flange and arranged in a matrix within the molten salt cylinder. The flange and support bars provide support for the heating tubes, and the support bars are thin-diameter steel bars. Heating tubes at the same horizontal level within the molten salt cylinder are connected in series in the junction box via wires to form a horizontal heating tube group. Support bars provide mechanical support between horizontal heating tube groups and between the horizontal heating tube groups and the molten salt cylinder. The molten salt inlet and outlet are located at the upper and lower horizontal ends of the molten salt cylinder, respectively.

[0019] Furthermore, the longitudinally fine-tuning molten salt electric heater includes a molten salt cylinder, first, second to Qth vertical heating elements, a molten salt inlet, and a molten salt outlet, where Q is a positive integer greater than or equal to 1. Molten salt flows into the molten salt cylinder from the molten salt inlet, contacts the first, second to Qth vertical heating elements, and flows out from the molten salt outlet. The first, second to Qth vertical heating elements are arranged perpendicularly to the molten salt cylinder. Each vertical heating element includes a junction box, first, second to ith heating tubes, a flange, and a support bar. The first, second to ith heating tubes are all inserted into the flange, and the flange and support bar provide support for the heating tubes.

[0020] Furthermore, the control module obtains real-time fluctuation data of the new energy source through a power measurement sensor, calculates the required power, flow rate, and valve opening of each component in the coarse and fine adjustment molten salt electric heating system, and sends this command to the power module, pump, and valves for execution. The power module is connected to the coarse and fine adjustment molten salt electric heaters. The power module is a multi-thyristor anti-parallel circuit or a multi-converter device. The thyristor anti-parallel circuit includes thyristors connected in parallel in at least two directions. If the power module is a thyristor anti-parallel circuit, one end is connected to the high-voltage grid bus. When connected to the coarse adjustment molten salt electric heater, the other end is connected to the two ends formed by the series connection of the heating tubes in the coarse adjustment molten salt electric heater. When connected to the fine adjustment molten salt electric heater, the power module is connected to the two ends of the horizontal heating tube group in the transverse fine adjustment molten salt electric heater or to the vertical heating tube group in the longitudinal fine adjustment molten salt electric heater. The converter device includes components from the first, second, to Yth... An AC / DC / DC converter has its output ports connected in series or parallel. Each AC / DC / DC converter includes a transformer, an AC / DC module, a voltage regulator capacitor, and a DC / DC module. The positive terminal formed by the output port of the AC / DC module is connected to the positive terminal of the voltage regulator capacitor, and the positive terminal of the voltage regulator capacitor is connected to the positive terminal of the input port of the DC / DC module. The negative terminal formed by the output port of the AC / DC module is connected to the negative terminal of the voltage regulator capacitor, and the negative terminal of the voltage regulator capacitor is connected to the negative terminal of the input port of the DC / DC module.

[0021] Beneficial effects:

[0022] 1. In this invention, the electric heaters are arranged in an array, which enables high-power deployment and operation of molten salt electric heating;

[0023] 2. In this invention, the coarse-adjustment molten salt electric heating system and the fine-adjustment molten salt electric heating system can absorb the fluctuating power of new energy sources within a wide operating range;

[0024] 3. In this invention, the coarse-adjustment molten salt electric heating system can quickly respond to fluctuations in new energy power.

[0025] 4. In this invention, the buffer system and the fine-tuning molten salt electric heating system can ensure that the outlet temperature of the molten salt electric heating is constant. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an array molten salt electric heating system according to Embodiment 1 of the present invention;

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

[0028] Figure 3 This is a schematic diagram of the coarse-adjustment molten salt electric heater used in Embodiment 1 of the present invention;

[0029] Figure 4This is a schematic diagram of the transverse fine-tuning molten salt electric heater structure used in Embodiment 1 of the present invention;

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

[0031] Figure 6 This is a schematic diagram of the anti-parallel thyristor circuit provided in Embodiment 1 of the present invention;

[0032] Figure 7 This is a schematic diagram of the converter device provided in Embodiment 1 of the present invention.

[0033] The attached figures are labeled as follows: 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-Interconnected molten salt valve, 1007-Bypass molten salt valve, 1008-Coarse adjustment molten salt electric heater, 1009-First temperature sensor, 1010-Bypass molten salt pipeline, 1011-Coarse adjustment self-locking molten salt electric heater, 1012-Drain valve, 2001-Buffer tank, 3001-Fine adjustment self-locking molten salt electric heater, 3003-Fine adjustment molten salt electric heater. 3002-Hot tank, 1008-1 Molten salt cylinder, 1008-2 Electric heating tube, 1008-3 Junction 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 assembly, 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-Yth AC / DC / DC converter. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

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

[0036] Furthermore, the coarse-adjustment molten salt electric heating array includes first, second to Nth coarse-adjustment molten salt electric heater groups, wherein the coarse-adjustment molten salt electric heater group refers to... Figure 1 A group is formed by connecting three branches in series with two other three-in-series loops in parallel, where N is a positive integer greater than 1. It may also include 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 via molten salt pipe 1003, and are arranged from high to low in the horizontal direction.

[0037] The coarse-adjustment molten salt electric heater group includes first, second to Mth coarse-adjustment self-locking molten salt electric heater strings, which are connected in parallel sequentially through molten salt pipe 1003, where M is a positive integer greater than or equal to 1. The coarse-adjustment self-locking molten salt electric heater string includes first, second to Pth coarse-adjustment self-locking molten salt electric heaters 1011, where all coarse-adjustment self-locking molten salt electric heaters 1011 are connected in series, where P is a positive integer greater than or equal to 1. The coarse-adjustment self-locking molten salt electric heater 1011 includes a first self-locking molten salt valve 1005-1, a second self-locking molten salt valve 1005-2, a salt drain valve 1012, a coarse-adjustment molten salt electric heater 1008, and a first temperature sensor 1009. The first self-locking molten salt valve 1005-1, the coarse-adjustment molten salt electric heater 1008, and the second self-locking molten salt valve 1005-2 are connected in series through a molten salt pipeline 1003. The first temperature sensor 1009 is installed after the second self-locking molten salt valve 1005-2. One end of the salt drain valve 1012 is connected in parallel with the outlet of the coarse-adjustment molten salt electric heater 1008.

[0038] like Figure 2As shown, the interconnection device includes an interconnection 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 coarse adjustment molten salt electric heater group are interconnected with the outlets of the first, second to pth coarse adjustment self-locking molten salt electric heaters 1011 in the (m+1)th coarse adjustment molten salt electric heater group through the interconnection molten salt valve 1006, where 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 through the bypass molten salt pipeline 1010. 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, 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 coarse adjustment molten salt electric heater strings through the bypass molten salt valve 1007. The first temperature sensor 1009 is installed at the far end of the process along the parallel connection point.

[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 heating elements 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 plate 1008-7. The heating elements 1008-2 can be U-shaped or cylindrical. The first, second, and Xth heating elements 1008-2 are all inserted into the flange 1008-4 and the baffle plate 1008-7, and are distributed within the molten salt cylinder 1008-1. The flange 1008-4 and the baffle plate 1008-7 provide support for the heating elements 1008-2. The first, second, and Xth heating elements 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, with the molten salt inlet 1008-5 and outlet 1008-6 located at the upper and lower horizontal ends of the molten salt cylinder 1008-1, respectively. The second temperature sensor 1008-8 is located at 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 coarse-tuning molten salt electric heater groups in the coarse-tuning molten salt electric heating array with fine-tuning self-locking molten salt electric heaters 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 drain valve 1012, the 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 connected in series through a molten salt pipe 1003. The first temperature sensor 1009 is installed after the second self-locking molten salt valve 1005-2. One end of the salt drain valve 1012 is connected in parallel with 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 transverse fine-tuning molten salt electric heater and a longitudinal fine-tuning molten salt electric heater. The transverse and longitudinal directions are defined based on whether the arrangement direction of the heating elements in the electric heater is the same as or perpendicular to the fluid flow direction. The transverse fine-tuning molten salt electric heater includes a molten salt cylinder 1008-1, first, second to i-th heating elements 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 support bar 1008-9, where i is a positive integer greater than or equal to 1. The heating element 1008-2 can be a U-shaped heating element or a cylindrical heating element. The first, second, and i-th heating elements 1008-2 are all inserted onto flange 1008-4, arranged in a matrix within the molten salt cylinder 1008-1. Flange 1008-4 and support bars 1008-9 provide support for the heating elements 1008-2; the support bars are thin-diameter steel bars. Heating elements 1008-2 at the same horizontal level within the molten salt cylinder are connected in series via wires in junction box 1008-3 to form a horizontal heating element group 1008-10. Support bars 1008-9 provide mechanical support between horizontal heating element groups and between horizontal heating element groups 1008-10 and the molten salt cylinder 1008-1. The molten salt inlet 1008-5 and outlet 1008-6 are located at the upper and lower horizontal ends of the molten salt cylinder 1008-1, respectively.

[0044] like Figure 5As shown, the longitudinally fine-tuning molten salt electric heater includes a molten salt cylinder 1008-1, first, second to Qth vertical heating elements, 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 Qth vertical heating elements, and flows out from the molten salt outlet 1008-6. The first, second to Qth vertical heating elements are arranged perpendicularly to the molten salt cylinder 1008-1. Each vertical heating element includes a junction box 1008-3, first, second to ith heating elements 1008-2, a flange 1008-4, and a support bar 1008-9. The heating element 1008-2 can be a U-shaped heating element or a cylindrical heating element. The first, second to i-th heating elements are all inserted into the flange 1008-4. The flange 1008-4 and the support bar 1008-9 provide support for the heating element 1008-2. Preferably, the support bar 1008-9 is a thin-diameter steel bar.

[0045] like Figure 6 As shown, the control module obtains real-time fluctuation data of the new energy source through a power measurement sensor, calculates the required power, flow rate, and valve opening degree for both the coarse-adjustment and fine-adjustment molten salt electric heating systems, and sends these instructions to the power module, pump, and valves for execution. The power module is connected to both the coarse-adjustment and fine-adjustment molten salt electric heating systems. The power module can be multiple anti-parallel thyristor circuits or multiple converter devices. The anti-parallel thyristor circuit includes at least two thyristors 4001 connected in parallel in two directions. If the power module is a thyristor anti-parallel circuit, one end of it is connected to the high-voltage grid bus 4002. When connected to the coarse-adjustment molten salt electric heater 1008, the other end is connected to the two ends formed by the series connection of the heating tube 1008-2 in the coarse-adjustment molten salt electric heater 1008. When connected to the fine-adjustment molten salt electric heater 3003, the power module is connected to the two ends of the horizontal heating tube group 1008-10 in the fine-adjustment molten salt electric heater 3003 or to the vertical heating group in the longitudinal fine-adjustment molten salt electric heater respectively.

[0046] like Figure 7As shown, the converter device includes a first AC / DC / DC converter 4006-1, and second to Yth AC / DC / DC converters 4006-Y, whose output ports are connected in series or 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. The positive terminal formed by the output port of the AC / DC module 4004 is connected to the positive terminal of the voltage stabilizing capacitor 4005, and the positive terminal of the voltage stabilizing capacitor 4005 is connected to the positive terminal of the input port of the DC / DC module 4007; the negative terminal formed by the output port of the AC / DC module 4004 is connected to the negative terminal of the voltage stabilizing capacitor 4005, and the negative terminal of the voltage stabilizing capacitor 4005 is connected to the negative terminal of the input port of the DC / DC module 4007. 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] The technical approach of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An array molten salt electric heating energy storage system, characterized in that: It includes the first, second to Zth molten salt electric heating systems, a buffer system, a pump, a power supply and a control system, Z is a positive integer and is greater than 1; the first, second to Lth molten salt electric heating systems are of the same structure, comprising a cold tank, a molten salt pipeline, a pump, and a coarse-adjustment molten salt electric heating array, wherein 1≤L≤Z-1; the buffer system comprises a molten salt pipeline and a buffer container; the L+1th to Zth molten salt electric heating systems are of the same structure, comprising a hot tank, a molten salt pipeline, a pump, and a fine-adjustment molten salt electric heating array; the power supply and control system comprises 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 pump and the L+1th molten salt electric heating system are connected in series in sequence through the molten salt pipeline, and the L+1th to Zth molten salt electric heating systems are connected in series in sequence.

2. The array molten salt electric heating energy storage system according to claim 1 is characterized in that: The coarse adjustment molten salt electric heating arrays in the first, second, and consecutive to Lth molten salt electric heating systems include first, second to Nth coarse adjustment molten salt electric heater groups, N is a positive integer and 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.

3. The array molten salt electric heating energy storage system according to claim 2 is 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 group strings, and are sequentially connected in parallel through the molten salt pipeline, M is a positive integer and is greater than or equal to 1; the coarse adjustment self-locking molten salt electric heater group string includes the first, second to Pth coarse adjustment self-locking molten salt electric heaters, wherein all the coarse adjustment self-locking molten salt electric heaters are connected in series, P is a positive integer and is greater than or equal to 1; The coarse adjustment self-locking molten salt electric heater comprises 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.

4. The array molten salt electric heating energy storage system according to claim 2 is characterized in that: 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.

5. The array molten salt electric heating energy storage system according to claim 2 is characterized in that: The molten salt bypass device comprises 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 sequentially connected in series 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.

6. The array molten salt electric heating energy storage system according to claim 3 is characterized in that: The coarse-adjustment molten salt electric heater includes a molten salt cylinder, first, second, and consecutive 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 in the junction box through wires; the baffles are evenly distributed on the process of the molten salt electric heater, and the molten salt inlet and outlet are respectively located at the horizontal upper end and lower end of the molten salt cylinder; the temperature sensor is located at the baffle.

7. The array molten salt electric heating energy storage system according to claim 1, characterized in that: The buffer container of the buffer system is at least one buffer tank or at least one pipeline 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.

8. The array molten salt electric heating energy storage system according to claim 1, characterized in that: 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 composed of all coarse-tuning molten salt electric heaters in the coarse-tuning molten salt electric heating array with a fine-tuning self-locking molten salt electric heater; the fine-tuning self-locking molten salt electric heater comprises a first self-locking molten salt valve, a second self-locking molten salt valve, a salt discharge valve, a fine-tuning molten salt electric heater and a temperature sensor, wherein 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 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-tuning molten salt electric heater; the fine-tuning molten salt electric heater is a transverse fine-tuning molten salt electric heater or a longitudinal fine-tuning molten salt electric heater, and the transverse and longitudinal directions are defined according to the arrangement direction of the electric heating group in the electric heater being the same as or perpendicular to the fluid flow direction.

9. The array molten salt electric heating energy storage system according to claim 8, characterized in that: The horizontal fine-tuning molten salt electric heater comprises a molten salt cylinder, first, second, and i-th electric heating tubes, a junction box, a flange, a molten salt inlet, a molten salt outlet, and a support bar, i is a positive integer and is greater than or equal to 1; the electric heating tube is a U-shaped electric heating tube or a cylindrical electric heating tube; The first, second, and consecutively to the i-th electric heating tubes are all inserted on the flange and dispersedly arranged in the molten salt cylinder in a matrix. The flange and the support bars provide support for the electric heating tubes, and the support bars are thin-diameter steel bars. Among them, the electric heating tubes in the same horizontal plane in the molten salt cylinder are connected in series through wires in the junction box to form a horizontal electric heating tube group, and mechanical support is provided by the support bars between the horizontal electric heating tube groups and between the horizontal electric heating tube groups and the molten salt cylinder; the molten salt inlet and outlet are respectively located at the horizontal upper end and lower end of the molten salt cylinder.

10. The array molten salt electric heating energy storage system according to claim 9, characterized in that: The longitudinal fine-tuning molten salt electric heater comprises a molten salt cylinder, the first, second to Qth vertical electric heating groups, a molten salt inlet and a molten salt outlet, where Q is a positive integer and is greater than or equal to 1; the molten salt flows into the molten salt cylinder from the molten salt inlet, contacts the first, second to Qth vertical electric heating groups, and flows out from the molten salt outlet; the first, second to Qth vertical electric heating groups are arranged vertically to the molten salt cylinder; the vertical electric heating group comprises a junction box, the first, second to i-th electric heating tubes, a flange and a support bar; the first, second to i-th electric heating tubes are all inserted into the flange, and the flange and the support bar provide support for the electric heating tubes.

11. The array molten salt electric heating energy storage system according to claim 1, characterized in that: The control module obtains the real-time fluctuation data of new energy through the power measurement sensor, and calculates the required power, flow and opening of each valve of the coarse adjustment and fine adjustment molten salt electric heating system, and sends the instruction to the power module, pump and valve for execution; the power module is connected to the coarse adjustment and fine adjustment molten salt electric heater; the power module is a plurality of thyristor anti-parallel circuits or a plurality of current conversion devices, and the thyristor anti-parallel circuit includes thyristors connected in parallel in at least two directions; if the power module is a thyristor anti-parallel circuit, one end thereof is connected to the high-voltage power grid bus, and when the coarse adjustment molten salt electric heater is connected, the other end is connected to the two ends formed by the electric heating tubes in the coarse adjustment molten salt electric heater in series; when the fine adjustment molten salt electric heater is connected, the power module is connected to the two ends of the horizontal electric heating tube group in the horizontal fine adjustment molten salt electric heater or is respectively connected to the vertical electric heating group in the longitudinal fine adjustment molten salt electric heater; the current conversion device includes a first, a second to a Y The output ports of the AC / DC / DC converter are connected in series or in parallel; the AC / DC / DC converter includes a transformer, an AC / DC module, a voltage-stabilizing capacitor and a DC / DC module; the positive electrode formed by the output port of the AC / DC module is connected to the positive electrode of the voltage-stabilizing capacitor, and the positive electrode of the voltage-stabilizing capacitor is connected to the positive electrode of the input port of the DC / DC module; the negative electrode formed by the output port of the AC / DC module is connected to the negative electrode of the voltage-stabilizing capacitor, and the negative electrode of the voltage-stabilizing capacitor is connected to the negative electrode of the input port of the DC / DC module.

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