Electric heating fused salt heat storage-heat supply system for quickly absorbing wind and light output fluctuation

Abstract

The invention relates to an electric heating fused salt heat storage-heat supply system for quickly absorbing wind and light output fluctuation. The electric heating fused salt heat storage-heat supply system comprises a low-temperature fused salt tank, a high-temperature fused salt tank, a multi-stage electric heater array, a fused salt pump, a regulating valve, a switch valve, a temperature measuring point, a preheater, an evaporator, a superheater, a water supply pump, a water supply unit and a matched pipeline. The system adopts hierarchical control: a first-stage electric heater array operates at a constant flow within a set time so as to respond to power fluctuation from a second stage to a minute stage; and the second-stage electric heater array is used for coping with minute-level to hour-level power fluctuation by adjusting the flow of the molten salt and stabilizing the temperature of a molten salt outlet. In the occasion where the temperature of the high-temperature molten salt needs to be strictly controlled, the system can guarantee the temperature quality of the high-temperature molten salt by additionally arranging a molten salt loop. The heat sink effect of the molten salt in the low-temperature molten salt tank can effectively buffer temperature sudden change and stabilize a flow field. Qualified high-temperature fused salt can be continuously output under high-fluctuation electric energy input, and steam is stably supplied.

Description

Technical Field

[0001] This invention relates to the field of energy storage, specifically to an electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output. Background Technology

[0002] The output of new energy sources such as wind and solar power is random, fluctuating, and intermittent, posing significant challenges to grid power balance and leading to prominent issues of wind and solar curtailment. Meanwhile, end-user heat supply still relies heavily on fossil fuels, resulting in significant pressure to reduce carbon emissions. Converting new energy electricity into heat can alleviate the decarbonization pressure on the heating sector and improve the absorption capacity of new energy electricity. Therefore, promoting the on-site conversion of new energy into heat not only provides flexible loads for the power system and enhances its absorption capacity, but also reduces heating costs for industrial users, making it particularly suitable for industrial scenarios with stable and continuous heating needs.

[0003] However, a source-load mismatch exists between renewable energy output and industrial heat load. To achieve decoupling and time-of-use transfer of electrical and thermal energy, thermal storage systems become crucial. Among these, electrically heated molten salt thermal storage technology is one effective way to achieve energy transfer and power smoothing. Currently, this technology is mainly applied in scenarios supported by large power grids or stable power sources. With the increasing penetration of renewable energy and the development of new energy consumption models such as zero-carbon parks, off-grid systems, and isolated grid operation, the proportion of independent energy supply scenarios without large power grid support is gradually increasing. In such scenarios, electrically heated molten salt thermal storage systems need to cope with power fluctuations from renewable energy sources, placing higher demands on the system's dynamic response capability, robustness, and control precision. Due to the large fluctuation range of renewable energy output, existing electrically heated molten salt thermal storage systems in these scenarios cannot quickly absorb power surges ranging from seconds to minutes, easily leading to overheating damage of the electric heater or substandard molten salt temperature. Therefore, how to achieve rapid power response, flexible adjustment, and continuous stable heating of the thermal storage module under conditions of drastic power fluctuations at the source has become a key task. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output includes:

[0007] Low-temperature molten salt tanks are used to store low-temperature molten salt.

[0008] High-temperature molten salt tanks are used to store high-temperature molten salt.

[0009] A multi-stage heater array, including at least a first-stage electric heater array and a second-stage electric heater array, is used to absorb new energy output, convert electrical energy into heat energy and transfer it to molten salt;

[0010] The first and second cryogenic molten salt pumps are located inside the cryogenic molten salt tank and are used to pump cryogenic molten salt from the cryogenic molten salt tank.

[0011] A high-temperature molten salt pump, located inside a high-temperature molten salt tank, is used to pump high-temperature molten salt from the tank; a flow regulating device is used to regulate the fluid flow rate;

[0012] A switching valve, installed on the pipeline between the heater and the high-temperature molten salt tank, is used to control the flow direction of the molten salt;

[0013] The first and second temperature measuring points are used to feed back temperature signals to control the molten salt flow rate and the direction of the diverting valve.

[0014] A steam supply unit is used to produce high-temperature steam by utilizing the heat of high-temperature molten salt;

[0015] The control center is used to allocate power to each level of the electric heater array;

[0016] Matching piping is provided for connecting the aforementioned components;

[0017] When absorbing renewable energy output, the control center is configured to allocate the high-fluctuation electrical energy from the renewable energy output to the primary electric heater array and allocate the reference power component of the renewable energy output to the secondary electric heater array; the cryogenic molten salt in the cryogenic molten salt tank is pumped to the primary and secondary electric heater arrays for heating; the molten salt heated by the primary electric heater array returns to the cryogenic molten salt tank; the molten salt that reaches the required temperature after being heated by the secondary electric heater array enters the high-temperature molten salt tank; during heating, the high-temperature molten salt is pumped out from the high-temperature molten salt tank and flows through the steam generating unit, and returns to the cryogenic molten salt tank after releasing heat.

[0018] Furthermore, the control center is configured to decompose the renewable energy output into a high-fluctuation power component and a reference power component, and allocate the high-fluctuation power component to the primary electric heater array and the reference power component to the secondary electric heater array. The high-fluctuation power component exhibits rapid fluctuation characteristics and high-frequency variation features on the order of seconds to minutes (within 1 second to 20 minutes); the reference power component exhibits continuous characteristics and low-frequency variation features on the order of tens of minutes to hours. The time scale of power allocation can be set according to specific application scenarios. The power allocation method of the control center includes: based on historical operating data and wind and solar resource prediction, through power... The predictive signal decomposition algorithm, based on variational mode decomposition or empirical mode decomposition, decomposes the renewable energy output into the high-fluctuation power component and the baseline power component. The allocation strategy can be dynamically adjusted according to seasonal changes and the fluctuation characteristics of wind and solar resources. The power allocation method also includes dynamically adjusting the power allocation ratio of the primary and secondary electric heater arrays based on the output prediction results and the real-time operating status of the system, thereby achieving precise absorption of high-fluctuation electricity. The power allocation method is also coordinated with the power capacity of the primary and secondary electric heater arrays to ensure that the allocation strategy is effectively implemented within the safe operating range of the equipment.

[0019] Furthermore, the cryogenic molten salt tank, the first cryogenic molten salt pump, the first molten salt regulating valve in the flow regulating device, the primary electric heater array, and the corresponding pipelines and power supply constitute an instantaneous power absorption unit within 1 second to 20 minutes; the power capacity configuration of the primary electric heater array covers the maximum value of local renewable energy output fluctuations; the cryogenic molten salt tank is used to store cryogenic molten salt, and stores molten salt heated by the primary electric heater array and molten salt from the high-temperature molten salt circuit; the cryogenic molten salt tank is configured to rely on the stored heat capacity in the cryogenic molten salt tank to suppress temperature fluctuations inside the tank; molten salt is extracted from the bottom of the cryogenic molten salt tank; molten salt enters the tank from the top of the molten salt tank; The first cryogenic molten salt pump operates at the designed maximum molten salt flow rate for a set time, and the flow rate remains constant. The large flow rate ensures that the molten salt undergoes sufficient heat exchange within the electric heater, enabling the primary electric heater array to directly and quickly respond to high-frequency power fluctuations without relying on the response delay of flow regulation. This meets the fluctuation absorption requirements from seconds to several minutes (within 1 second to 20 minutes). The set time and maximum molten salt flow rate are matched with the typical high-frequency fluctuation cycle of local wind and solar power output, and can be periodically adjusted by the first cryogenic molten salt pump and the first molten salt regulating valve in the flow control device. The time scale of the power distribution can be set according to the specific application scenario.

[0020] Furthermore, the high-temperature molten salt tank, the second low-temperature molten salt pump, the second molten salt regulating valve in the flow regulating device, the secondary electric heater array, the first temperature measuring point and the second temperature measuring point, the main switch valve and the loop switch valve in the valve device, and the corresponding pipelines and power supply constitute a reference power absorption unit ranging from tens of minutes to hours. When the allocated power changes, the control center adjusts the molten salt flow rate by adjusting the second low-temperature molten salt pump and the second molten salt regulating valve in the flow control device based on the molten salt power-flow curve, so that the molten salt outlet temperature of the secondary electric heater array is stabilized within a preset range.

[0021] Furthermore, the primary and / or secondary electric heater arrays are configured in at least one of the following ways: consisting of N electric heaters connected in series; consisting of N electric heaters connected in parallel; consisting of N electric heaters in a hybrid series and parallel configuration; the electric heater arrays are powered by a supporting power supply system, which is directly connected to the new energy power generation system; in the parallel or hybrid connection configuration, the rated power of each electric heater branch can be configured independently, and may be the same or different from each other; each electric heater branch is equipped with an independent flow regulating valve to control the flow rate of molten salt flowing through each branch; by coordinating the control of the power and molten salt flow rate of each branch, the system can achieve rapid response and flexible adjustment to fluctuations in new energy output.

[0022] Furthermore, a high-temperature molten salt return pipeline is added between the downstream of the secondary electric heater array and the upstream of the high-temperature molten salt tank, extending from the outlet of the secondary electric heater array to the low-temperature molten salt tank. This pipeline is equipped with a first temperature measuring point and the main switch valve and loop switch valve in the valve device. In scenarios where strict control of the high-temperature molten salt temperature is required, the temperature of the molten salt flowing through this pipeline is monitored in real time through the first temperature measuring point. When the system experiences a sudden drop in power, causing the molten salt temperature to fall below the entry temperature of the high-temperature molten salt tank, the loop switch valve is opened and the main switch valve is closed simultaneously, allowing the molten salt that has not reached the required temperature to return directly to the low-temperature molten salt tank through the return pipeline, thereby ensuring that the molten salt temperature in the high-temperature molten salt tank remains stable within the required range.

[0023] Furthermore, the fluctuation absorption method includes a power surge absorption strategy and a power drop absorption strategy: When there is a transient power surge: if the power fluctuation amplitude is within the rated power coverage range of the primary electric heater array and lasts for several seconds to several minutes (1 second to 20 minutes), the primary electric heater array absorbs the fluctuation quickly on its own; if the power fluctuation amplitude exceeds the rated power of the primary electric heater array and lasts for several seconds to several minutes (1 second to 20 minutes), within the safety threshold, power is preferentially allocated to the primary electric heater array, while simultaneously increasing the power allocation ratio of the secondary electric heater array to collaboratively absorb the excess fluctuation power, and immediately rapidly increasing the molten salt flow rate of the secondary electric heater array to a high value. During this stage, the flow rate adjustment focuses on rapidly absorbing the instantaneous power fluctuation; after the power fluctuation returns to the rated power range of the primary electric heater array, the control center reduces the molten salt flow rate of the secondary electric heater array to rematch it with the current reference power; during the fluctuation absorption period, In scenarios where strict control of the high-temperature molten salt temperature is not required, the molten salt heated by the secondary electric heater directly enters the high-temperature molten salt tank. In scenarios where strict control of the high-temperature molten salt temperature is required, molten salt that has not reached the set temperature after being heated by the secondary electric heater is returned to the low-temperature molten salt tank through the high-temperature molten salt return pipeline described in claim 6. When the overall power increases significantly and lasts for tens of minutes to several hours, the primary and secondary electric heater arrays are adjusted simultaneously: first, the power of the primary electric heater array is increased to its safe operating limit to maximize the absorption of transient fluctuation components; then, the control center reallocates the rated power share of the secondary electric heater array according to the baseline power demand after the power stabilizes, and adjusts its molten salt flow rate according to the preset molten salt power-flow curve to ensure that the molten salt temperature at the outlet of the secondary electric heater array is stable within the set range; at the same time, the power load of the primary electric heater array is reduced, ultimately allowing the primary electric heater array to return to the preset working state for high-frequency fluctuation absorption.

[0024] Furthermore, when the transient power drops sharply: if the power fluctuation is within the adjustment capability of the primary electric heater array and lasts for seconds to several minutes (1 second to 20 minutes), the primary electric heater array will quickly absorb the transient fluctuation by adjusting its own power; if the power drop is too large, causing the reference power component to drop synchronously and recover within a few minutes: the control center will maintain the current molten salt flow rate of the secondary electric heater array unchanged. In scenarios where strict control of the high-temperature molten salt temperature is not required, the molten salt heated by the secondary electric heater enters the high-temperature molten salt tank. In scenarios where strict control of the high-temperature molten salt temperature is required, molten salt that has not reached the set temperature after being heated by the secondary electric heater array returns to the low-temperature molten salt tank through the high-temperature molten salt return pipeline for reheating. When the power drops too drastically and lasts for tens of minutes to more than ten hours, the control center simultaneously reduces the electric heating power of the secondary electric heater array and correspondingly reduces the molten salt flow rate according to the preset molten salt power-flow curve, so that the system output and input power are rematched. When the power continues to drop to the point where wind and solar resources are completely interrupted, the control center shuts down the secondary electric heater array, leaving only the primary electric heater array in standby mode.

[0025] Furthermore, the steam supply unit comprises a high-temperature molten salt tank, a high-temperature molten salt pump in the flow regulation device, a steam superheater, a steam generator, a water preheater, a water supply pump in the flow regulation device, a water supply unit, a third molten salt regulating valve in the flow regulation device, a water regulating valve in the flow regulation device, and corresponding pipelines and a power supply. During heating, the high-temperature molten salt pump pumps high-temperature molten salt from the high-temperature molten salt tank. After passing through the steam superheater, steam generator, and water preheater, the cooled low-temperature molten salt flows back to the low-temperature molten salt tank. Water is pumped from the water supply unit by the water supply pump, flows through the water preheater, steam generator, and steam superheater, and absorbs the heat released by the molten salt to complete the preheating, vaporization, and superheating processes in sequence, ultimately forming high-temperature steam that meets the user's parameter requirements and is supplied to the user. Flexible control of the heating process can be achieved by adjusting the high-temperature molten salt pump, the third molten salt regulating valve, the water supply pump, and the water regulating valve.

[0026] Furthermore, the low-temperature molten salt tank is filled with inert solid particles as a heat sink. When these inert solid particles are filled, their core function is to suppress temperature fluctuations of the molten salt inside the tank through the heat capacity characteristics of the particles themselves, and to optimize the flow field distribution inside the tank through the spatial filling effect of the particles, thereby reducing molten salt flow disturbances. The inert solid particles must meet the requirements of being compatible with the molten salt used in the system within the operating temperature range, not undergoing chemical reactions, not producing toxic or harmful substances, and not undergoing significant phase changes or decompositions. The filling amount of the solid particles can be set according to the system's heat storage scale, fluctuation absorption requirements, and flow field optimization objectives.

[0027] The time scale of this invention, from seconds to several minutes, refers to a period of 1 second to 20 minutes, and several minutes refers to a period of 20 minutes; the time scale can be set according to the specific application scenario.

[0028] Beneficial effects:

[0029] 1. This invention constructs two-level power absorption units, instantaneous and reference, and coordinates multiple control mechanisms such as power decomposition and flow regulation to accurately match and classify the fluctuations in new energy output from the second level to the hour level, which can significantly improve the system's absorption capacity and response speed for highly volatile renewable energy.

[0030] 2. This invention, by adding a high-temperature molten salt return pipeline, returns molten salt that has not reached the required temperature to the low-temperature molten salt tank, thus ensuring the temperature quality of the molten salt in the high-temperature molten salt tank.

[0031] 3. This invention establishes a temperature buffer system by adopting a high-flow-rate operation strategy in the primary electric heater and coordinating the heat sink effect of the cold salt stock and / or solid particles in the low-temperature molten salt tank, thereby enhancing the system's operational robustness under complex operating conditions.

[0032] 4. This invention uses molten salt thermal storage and steam generation units to convert fluctuating electrical energy into stable and reliable thermal energy output, thereby decoupling the source-side fluctuation absorption and the user-side continuous heating, while ensuring the continuity and stability of energy supply quality. Attached Figure Description

[0033] Figure 1 This is a structural diagram of an electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to the present invention.

[0034] Figure 2 This is a schematic diagram of an instantaneous power absorption unit;

[0035] Figure 3 Schematic diagram of the reference power absorption unit;

[0036] Figure 4 This is a schematic diagram of a steam supply unit.

[0037] The attached diagram is labeled as follows: 1-Low-temperature molten salt tank; 2-High-temperature molten salt tank; 3-First-stage electric heater array; 4-Second-stage electric heater array; 5-First low-temperature molten salt pump; 6-Second low-temperature molten salt pump; 7-High-temperature molten salt pump; 8-First temperature measuring point; 9-Second temperature measuring point; 10-Main circuit switch valve; 11-Circuit switch valve; 12-Water preheater; 13-Steam generator; 14-Steam superheater; 15-Feed water unit; 16-Feed water pump; 17-First molten salt regulating valve; 18-Second molten salt regulating valve; 19-Third molten salt regulating valve; 20-Water regulating valve; 21-Control center. Detailed Implementation

[0038] 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.

[0039] like Figure 1 As shown, the electrically heated molten salt thermal storage-heating system of the present invention for rapidly absorbing fluctuations in wind and solar power output includes:

[0040] The thermal storage unit includes a low-temperature molten salt tank 1 and a high-temperature molten salt tank 2. The low-temperature molten salt tank can be filled with inert solid particles compatible with the properties of molten salt as heat sinks to stabilize temperature fluctuations and flow field within the tank. The low-temperature molten salt tank 1 is used to store low-temperature molten salt and molten salt from the high-temperature molten salt circuit. The high-temperature molten salt tank 2 is used to store high-temperature molten salt.

[0041] A multi-stage heater array, including at least a primary electric heater array 3 and a secondary electric heater array 4, is used to absorb renewable energy output, converting electrical energy into heat energy and transferring it to molten salt. A first cryogenic molten salt pump 5 is located inside a cryogenic molten salt tank 1, used to pump cryogenic molten salt to the primary electric heater array 3; a second cryogenic molten salt pump 6 is located inside a cryogenic molten salt tank 1, used to pump cryogenic molten salt to the secondary electric heater array 4. Each stage of the electric heater array consists of multiple electric heaters connected in series, parallel, or in a hybrid manner. In the parallel or hybrid connection method, the rated power of each electric heater branch can be configured independently, and they can be the same or different from each other. The supporting power supply system is directly connected to the renewable energy power generation system to achieve efficient conversion of electrical energy into heat energy.

[0042] The conveying and regulating unit includes a low-temperature molten salt pump, a high-temperature molten salt pump, a flow regulating device (molten salt regulating valve, water regulating valve), a switching valve, and a temperature measuring point. A high-temperature molten salt pump 7 is located inside the high-temperature molten salt tank 2 and is used to pump high-temperature molten salt into the steam supply unit; a first molten salt regulating valve 17 is used to regulate the flow rate of low-temperature molten salt to the primary electric heater array 3; a second molten salt regulating valve 18 is used to regulate the flow rate of low-temperature molten salt to the secondary electric heater array 4; a third molten salt regulating valve 19 is used to regulate the flow rate of high-temperature molten salt entering the steam supply unit; a main circuit switch valve 10 and a loop switch valve 11 are installed on the pipeline between the heater and the high-temperature salt tank to control the direction of molten salt flow; a first temperature measuring point 8 is located downstream of the secondary electric heater and upstream of the main circuit switch valve 10 and the loop switch valve 11, and controls the direction of molten salt flow by monitoring the molten salt temperature at the outlet of the secondary electric heater array; a second temperature measuring point 9 is located downstream of the second low-temperature molten salt pump 6 and upstream of the secondary electric heater array 4, and controls the second low-temperature molten salt pump 6 and the second molten salt regulating valve 18 by monitoring the molten salt inlet temperature of the secondary electric heater array; and a water regulating valve 20 is used to control the water flow rate.

[0043] The steam generating unit consists of a steam superheater, a steam generator, a water preheater, a feedwater pump, and a feedwater unit. The water preheater 12 is used to preheat water. The steam generator 13 is used to generate saturated steam. The steam superheater 14 is used to generate superheated steam. The feedwater unit 15 is used to supplement the water supply unit. The feedwater pump 16 is used to pump water to the steam supply unit and control the flow rate.

[0044] Control center 21 is used to decompose the renewable energy output into a high-fluctuation power component and a reference power component. The high-fluctuation power component is allocated to the primary electric heater array, and the reference power component is allocated to the secondary electric heater array. Based on historical operating data, wind and solar resource prediction results, and real-time system status, control center 21 uses power prediction and signal decomposition algorithms (such as signal decomposition algorithms based on variational mode decomposition or empirical mode decomposition) to decompose the renewable energy output into a high-fluctuation power component lasting from seconds to minutes (1 second to 20 minutes) and a stable reference power component lasting from tens of minutes to hours. The high-fluctuation power component is allocated to the primary electric heater array 3, and the reference power component is allocated to the secondary electric heater array 4. The allocation ratio between the two can be dynamically adjusted according to seasonal changes and wind and solar fluctuation characteristics. The control center further combines the output prediction results with the real-time system operating status to dynamically adjust the power allocation ratio between the primary and secondary electric heater arrays to achieve precise absorption of high-fluctuation energy. Simultaneously, the power allocation method is also coordinated with the power capacity of the primary and secondary electric heater arrays to ensure that the allocation strategy is effectively implemented within the safe operating range of the equipment.

[0045] The cryogenic molten salt tank 1, the first cryogenic molten salt pump 5, the first molten salt regulating valve 17, and the first-stage electric heater array 3 are connected by pipelines. The pipeline from the outlet of the first-stage electric heater array eventually returns to the cryogenic molten salt tank 1. Similarly, the high-temperature molten salt tank 2, the second cryogenic molten salt pump 6, the second molten salt regulating valve 18, and the second-stage electric heater array 4 are connected by pipelines. The pipeline from the outlet of the second-stage electric heater array 4 returns to the high-temperature molten salt tank 2. Furthermore, a separate pipeline from the outlet of the second-stage electric heater array 4 connects to the cryogenic molten salt tank 1, forming a high-temperature molten salt loop. The molten salt in the high-temperature molten salt tank 2 flows sequentially through the high-temperature molten salt pump 7, the high-temperature molten salt valve 19, the steam generator 13, the steam superheater 14, and the water preheater 12, finally returning to the cryogenic molten salt tank via the pipeline from the outlet of the water preheater, forming a complete molten salt circulation loop. When new energy power arrives, the control center 21 first uses a signal decomposition algorithm based on variational mode decomposition or empirical mode decomposition, combined with real-time monitoring data of wind and solar resources and short-term prediction results, to accurately decompose the new energy output into high-fluctuation power components at the level of seconds to several minutes (within 1 second to 20 minutes) and a reference power component at the level of tens of minutes to hours, and then prioritizes the allocation of the high-fluctuation power components to the primary electric heater array 3. Figure 2 The instantaneous power absorption unit is shown, comprising the cryogenic molten salt tank 1, a first cryogenic molten salt pump 5 (acting as the cryogenic molten salt pump), a first molten salt regulating valve 17 in the flow regulation device, a primary electric heater array 3, and corresponding piping and power supply, responsible for absorbing instantaneous power fluctuations ranging from seconds to minutes. The first cryogenic molten salt pump 5 pumps cryogenic molten salt from the bottom of the cryogenic molten salt tank 1, which then passes through the first molten salt regulating valve 17 and enters the primary electric heater array 3. The power capacity of the primary electric heater array 3 covers the maximum local renewable energy fluctuation value; the first and second cryogenic molten salt pumps operate at the designed maximum molten salt flow rate for a set time, and the flow rate remains constant; the set time and maximum molten salt flow rate match the typical high-frequency fluctuation cycle of local wind and solar power output and can be periodically adjusted. This unit adopts a high molten salt flow rate constant flow operation strategy. Even in the face of frequent and severe fluctuations in renewable energy power, the high flow rate design ensures sufficient heat exchange of the molten salt in the heating channel, avoiding local overheating of the molten salt and reducing the surface heat load of the electric heating wire, thus ensuring the safe operation of the electric heating element.

[0046] The specific flow rate can be set according to the local characteristics of renewable energy output. For example, the flow rate can be appropriately reduced in the summer when solar radiation is stable, and increased in the winter when wind power fluctuates greatly.

[0047] The molten salt, heated by the primary electric heater array 3, is fed into the cryogenic molten salt tank 1. This tank stores a large amount of cryogenic molten salt, forming a heat sink for the system and effectively mitigating temperature fluctuations, resulting in a more uniform and stable temperature at the bottom of the tank. This cryogenic molten salt, with its stable temperature and flow characteristics, enters the secondary electric heater array 4, reducing the frequency and amplitude of flow regulation on the secondary side. This lays the foundation for stable absorption of the reference power component and precise control of the outlet temperature.

[0048] Control center 21 allocates the reference power to the secondary electric heater array 4. Figure 3 The reference power absorption unit is shown, consisting of the high-temperature molten salt tank 2, the second low-temperature molten salt pump 6, the second molten salt regulating valve 18, the second-stage electric heater array 4, corresponding first and second temperature measuring points, the main circuit switch valve 10 and the loop switch valve 11, and corresponding pipelines and power supply branches. The second low-temperature molten salt pump 6 pumps low-temperature molten salt from the low-temperature molten salt tank 1, which then passes through the second molten salt regulating valve 18 and the second temperature measuring point 9 before entering the second-stage electric heater array 4. The system adjusts the flow rate of molten salt entering the second-stage electric heater array based on the monitoring data from the second temperature measuring point 9, the target high-temperature molten salt temperature, and the allocated reference power to ensure that the outlet molten salt temperature meets the requirements. The two-stage reference power absorption units operate in parallel through flow distribution and switching control of the conveying and regulating units, switching or cooperating according to the output of new energy sources to ensure the stability of the system's heating supply.

[0049] Figure 4 The steam supply unit is shown to consist of a high-temperature molten salt tank 2, a high-temperature molten salt pump 7 in the flow regulation device, a steam superheater 14, a steam generator 13, a water preheater 12, a water supply pump 16 in the flow regulation device, a water supply unit 15, a third molten salt regulating valve 19 in the flow regulation device, a water regulating valve 20 in the flow regulation device, and corresponding pipelines and a power supply. During heating, high-temperature molten salt is drawn from the high-temperature molten salt tank 2 by the high-temperature molten salt pump 7 and sent to the steam generator unit via the third molten salt regulating valve 19; it then flows sequentially through the steam superheater 14, the steam generator 13, and the water preheater 12, finally returning to the low-temperature molten salt tank 1. Water is pumped out from the water supply unit via the water supply pump, absorbing heat from the molten salt to complete preheating, vaporization, and superheating, forming high-temperature steam supplied to users; the cooled molten salt returns to the low-temperature molten salt tank, completing the cycle. Flexible heating can be achieved by adjusting the operating parameters of the molten salt pump and regulating valve.

[0050] The system formulates graded and coordinated response strategies for power drops of different magnitudes and durations, as follows:

[0051] When the output of new energy suddenly decreases for a short period of time (within 20 minutes) and the power fluctuation is within the adjustment capability range of the first-stage electric heater array 3, the power of the first-stage electric heater array 3 is reduced first to quickly absorb the transient fluctuation.

[0052] When the power drops too sharply, causing the reference power component to decrease synchronously and for a short period of time, the current molten salt flow rate of the secondary electric heater array 4 is kept constant to avoid system oscillations caused by frequent flow rate adjustments. The molten salt temperature is monitored through the first temperature measuring point 8. Since the molten salt flow rate is constant but the power decreases, the molten salt outlet temperature will be lower than the inlet temperature of the high-temperature molten salt tank in a short period of time. Therefore, the main circuit switch valve 10 is closed and the loop switch valve 11 is opened simultaneously, so that the molten salt returns to the low-temperature molten salt tank 1 through the high-temperature molten salt return pipeline for reheating.

[0053] When the power drops too much and lasts for a long time (tens of minutes to several hours), the power of the secondary electric heater array 4 is reduced simultaneously, and its molten salt flow rate is reduced accordingly according to the preset molten salt power-flow curve, so that the system output and input power are rematched; the power-flow curve is determined based on the energy balance relationship.

[0054] When the power continues to drop to near zero, the primary electric heater array is in standby mode, and the secondary electric heater array is turned off.

[0055] The system has also developed a graded and coordinated response strategy for power surges of different magnitudes and durations, as follows:

[0056] When the power fluctuation is within the rated power range of the primary electric heater array and the duration is short, it is quickly absorbed by the primary electric heater array alone. This is a common scenario for fluctuations in new energy output. Since the power capacity design of the primary electric heater array 3 has been pre-covered to cover the typical maximum fluctuation amplitude of local wind and solar power output, it can independently meet the needs of absorbing most transient fluctuations.

[0057] When the power fluctuation exceeds the rated power of the primary electric heater array 3 and the duration is short, this is considered an extreme fluctuation scenario. In this case, power is prioritized for allocation to the primary electric heater array 3, while the power allocation ratio of the secondary electric heater array is increased. The molten salt flow rate of the secondary electric heater array is quickly increased to a preset high level. During this stage, the flow rate is primarily aimed at quickly responding to and consuming power fluctuations. Once the power fluctuation subsides, the control center 21 lowers the molten salt flow rate of the secondary electric heater array to rematch it with the reference power. During the absorption process, molten salt that has not reached the set temperature after being heated by the secondary electric heater array 4 can be returned to the low-temperature molten salt tank 1 through the high-temperature molten salt return pipeline.

[0058] When the overall power increases significantly and lasts for a long time (tens of minutes to several hours), the primary and secondary electric heater arrays adjust simultaneously: first, the power of the primary electric heater array is increased to its safe operating limit to maximize the absorption of transient fluctuation components; then, the control center reallocates the rated power share of the secondary electric heater array according to the baseline power demand after the power stabilizes, and adjusts its molten salt flow rate according to the preset molten salt power-flow curve to ensure that the outlet molten salt temperature of the secondary electric heater array is stable within the set range; at the same time, the power load of the primary electric heater array is reduced, ultimately allowing the primary electric heater array to return to the preset operating state for high-frequency fluctuation absorption.

[0059] During heating, high-temperature molten salt is drawn from the high-temperature molten salt tank by the high-temperature molten salt pump and sent to the steam generation unit; the high-temperature molten salt releases heat as it flows through the steam generation unit, and returns to the low-temperature molten salt tank after cooling down; at the same time, the feedwater absorbs heat in the steam generation unit to generate qualified steam for supply to users.

[0060] Through the coordinated operation of a multi-stage electric heater array and a molten salt storage tank, the system can quickly absorb fluctuating power and maintain the molten salt temperature within a set range, thereby constructing a thermal storage-heating system with thermal storage as its core that can actively adapt to the characteristics of new energy output.

[0061] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output, characterized in that, include: Low-temperature molten salt tank (1), used for storing low-temperature molten salt; High-temperature molten salt tank (2) is used to store high-temperature molten salt; A multi-stage heater array, including at least a first-stage electric heater array (3) and a second-stage electric heater array (4), is used to absorb new energy output, convert electrical energy into heat energy and transfer it to molten salt; The first cryogenic molten salt pump (5) and the second cryogenic molten salt pump (6) are located inside the cryogenic molten salt tank and are used to pump cryogenic molten salt from the cryogenic molten salt tank (1). A high-temperature molten salt pump (7) is located inside a high-temperature molten salt tank and is used to pump high-temperature molten salt from the high-temperature molten salt tank (2); Flow regulating device, used to regulate fluid flow rate; A switching valve, installed on the pipeline between the heater and the high-temperature molten salt tank, is used to control the flow direction of the molten salt; The first temperature measuring point (8) and the second temperature measuring point (9) are used to feed back temperature signals to control the molten salt flow rate and the direction of the diverting valve; A steam supply unit is used to produce high-temperature steam by utilizing the heat of high-temperature molten salt; The control center (21) is used to allocate the power of each level of the electric heater array; Matching piping is provided for connecting the aforementioned components; When absorbing the output of new energy, the control center (21) is configured to allocate the high-fluctuation electrical energy of the new energy output to the primary electric heater array (3) and allocate the reference power component of the new energy output to the secondary electric heater array (4); the low-temperature molten salt in the low-temperature molten salt tank (1) is pumped to the primary electric heater array (3) and the secondary electric heater array (4) for heating; the molten salt heated by the primary electric heater array (3) returns to the low-temperature molten salt tank (1); the molten salt heated by the secondary electric heater array (4) enters the high-temperature molten salt tank (2); when supplying heat, the high-temperature molten salt is pumped out from the high-temperature molten salt tank (2) and flows through the steam generating unit, and returns to the low-temperature molten salt tank (1) after releasing heat.

2. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 1, characterized in that: The control center (21) is configured to decompose the new energy output into a high-fluctuation power component and a reference power component, and to allocate the high-fluctuation power component to the first-level electric heater array (3) and the reference power component to the second-level electric heater array (4). The high-fluctuation power component has rapid fluctuation characteristics and high-frequency change features within 1 second to 20 minutes; The reference power component has a continuous characteristic and low-frequency variation on the order of tens of minutes to hours; the time scale of power allocation can be set according to the specific application scenario. The power allocation method of the control center (21) includes: based on historical operating data and wind and solar resource prediction, the new energy output is decomposed into the high fluctuation power component and the reference power component through power prediction and signal decomposition algorithm based on variational mode decomposition or empirical mode decomposition. The allocation strategy can be dynamically adjusted based on seasonal changes and the fluctuating characteristics of wind and solar resources; The power allocation method also includes dynamically adjusting the power allocation ratio between the primary and secondary electric heater arrays based on the output prediction results and the real-time operating status of the system, thereby achieving precise absorption of highly fluctuating electrical energy. The power allocation method is also coordinated with the power capacity of the primary and secondary electric heater arrays to ensure that the allocation strategy is effectively implemented within the safe operating range of the equipment.

3. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 1, characterized in that: The cryogenic molten salt tank (1), the first cryogenic molten salt pump (5), the first molten salt regulating valve (17) in the flow regulating device, the first-stage electric heater array (3), and the corresponding pipes and power supply constitute an instantaneous power consumption unit within 1 second to 20 minutes. The time scale of power distribution can be set according to the specific application scenario. The power capacity configuration of the primary electric heater array covers the maximum value of local renewable energy output fluctuations; The cryogenic molten salt tank (1) is used to store cryogenic molten salt, and to store molten salt heated by the primary electric heater array and molten salt from the high-temperature molten salt circuit; The cryogenic molten salt tank (1) is configured to rely on the stored heat capacity in the cryogenic molten salt tank to suppress temperature fluctuations inside the tank; Molten salt is drawn from the bottom of the cryogenic molten salt tank; molten salt enters the tank from the top. The first cryogenic molten salt pump (5) operates at the designed maximum molten salt flow rate within a set time and the flow rate remains constant; the large flow rate ensures that the molten salt is fully heat-exchanged in the electric heater, enabling the first-stage electric heater array to directly and quickly respond to high-frequency fluctuation power without relying on the response delay of flow regulation, thereby meeting the fluctuation absorption requirements within 1 second to 20 minutes; wherein, the time scale of power distribution can be set according to the specific application scenario; The set time and maximum molten salt flow rate are matched with the typical high-frequency fluctuation cycle of local wind and solar power output, and are periodically adjusted by the first cryogenic molten salt pump (5) and the first molten salt regulating valve (17) in the flow control device.

4. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 1, characterized in that: The high-temperature molten salt tank (2), the second low-temperature molten salt pump (6), the second molten salt regulating valve (18) in the flow regulating device, the secondary electric heater array (4), the first temperature measuring point (8) and the second temperature measuring point (9), the main circuit switch valve (10) and the loop switch valve (11), as well as the corresponding pipelines and power supply, constitute a reference power absorption unit ranging from tens of minutes to hours. When the allocated power changes, the control center (21) adjusts the molten salt flow rate by adjusting the second low-temperature molten salt pump (6) and the second molten salt regulating valve (18) in the flow control device based on the molten salt power-flow curve obtained by the energy balance relationship, so that the molten salt outlet temperature of the secondary electric heater array (4) is stabilized within the preset range.

5. An electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output, as described in claim 1, 3, or 4, characterized in that: The primary and / or secondary electric heater array is configured in at least one of the following ways: It consists of N electric heaters connected in series, where N≥1 and N is an integer; It consists of N electric heaters connected in parallel, where N≥1 and N is an integer; It consists of N electric heaters connected in series and parallel, where N≥1 and N is an integer. The electric heater array is powered by a matching power system, which is directly connected to the new energy power generation system. In parallel or mixed connection methods, the rated power of each electric heater branch can be configured independently, and may be the same or different from each other; Each electric heating branch is equipped with an independent flow regulating valve to control the flow rate of molten salt through each branch. By coordinating and controlling the power and molten salt flow of each branch, the system can achieve rapid response and flexible adjustment to fluctuations in the output of new energy sources.

6. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 4, characterized in that: In cases where strict control of the high-temperature molten salt temperature is not required, the heated molten salt is directly transported to the high-temperature molten salt tank; in cases where strict control of the high-temperature molten salt temperature is required, a high-temperature molten salt return pipeline extending from the outlet end of the secondary electric heater array (4) to the low-temperature molten salt tank (1) is added to the pipeline between the downstream of the secondary electric heater array (4) and the upstream of the high-temperature molten salt tank (2). This pipeline is equipped with a first temperature measuring point (8) and the main switch valve (10) and the loop switch valve (11) in the valve device. In situations where strict control of the high-temperature molten salt temperature is required, the temperature of the molten salt flowing through the pipeline is monitored in real time by the first temperature measuring point (8). When the system experiences a sudden drop in power, causing the molten salt temperature to fall below the entry temperature of the high-temperature molten salt tank (2), the loop switch valve (11) is opened and the main switch valve (10) is closed simultaneously, so that the molten salt that has not reached the required temperature is returned directly to the low-temperature molten salt tank (1) through the return pipeline, thereby ensuring that the molten salt temperature in the high-temperature molten salt tank (2) remains stable within the required range.

7. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 1, characterized in that: Fluctuation mitigation methods include power surge mitigation strategies and power descent mitigation strategies: When transient power increases sharply: When the power fluctuation range is within the rated power coverage of the primary electric heater array and lasts for 1 second to 20 minutes, it is quickly absorbed by the primary electric heater array alone. When the power fluctuation exceeds the rated power of the primary electric heater array and lasts for 1 second to 20 minutes, within the safety threshold, the power is preferentially allocated to the primary electric heater array. At the same time, the power allocation ratio of the secondary electric heater array is simultaneously increased to jointly absorb the excess power fluctuation. The molten salt flow rate of the secondary electric heater array is immediately increased to a high value. During this stage, the flow rate adjustment is aimed at quickly absorbing the instantaneous power fluctuation. After the power fluctuation falls back to the rated power range of the primary electric heater array, the control center lowers the molten salt flow rate of the secondary electric heater array to match it with the current reference power. In scenarios where the high temperature molten salt temperature needs to be strictly controlled, during the fluctuation absorption period, the molten salt that has not reached the set temperature after being heated by the secondary electric heater is closed by the main switch valve (10) and the loop switch valve (11) is opened through the high temperature molten salt return pipeline as described in claim 6, so that the molten salt returns from the pipeline to the low temperature molten salt tank. When the overall power increases significantly and continues for tens of minutes to several hours, the primary and secondary electric heater arrays adjust simultaneously: First, the power of the primary electric heater array is increased to its safe operating limit to maximize the absorption of transient fluctuation components. Then, the control center reallocates the rated power share of the secondary electric heater array according to the baseline power demand after the power stabilizes, and adjusts its molten salt flow rate according to the preset molten salt power-flow curve to ensure that the outlet molten salt temperature of the secondary electric heater array is stable within the set range. At the same time, the power load of the primary electric heater array is reduced, ultimately allowing the primary electric heater array to return to the preset operating state for high-frequency fluctuation absorption.

8. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 7, characterized in that: When transient power drops sharply: When the power fluctuation is within the adjustment capability of the primary electric heater array and lasts for 1 second to 20 minutes, the primary electric heater array quickly absorbs the transient fluctuation by adjusting its own power; the time scale of power distribution can be set according to the specific application scenario. When the power drops suddenly, causing the reference power component to drop synchronously and recover within 20 minutes: the control center (21) maintains the current molten salt flow rate of the secondary electric heater array unchanged; for scenarios where the molten salt outlet temperature requirement is high, the molten salt that has not reached the set temperature after being heated by the secondary electric heater array (4) is returned to the low temperature molten salt tank (1) through the high temperature molten salt return pipeline described in claim 6, in order to be reheated; When the power drops too much and lasts for tens of minutes to several hours: the control center (21) simultaneously reduces the electric heating power of the secondary electric heater array and reduces its molten salt flow rate according to the preset molten salt power-flow curve, so that the system output and input power are rematched; When the power continues to drop to the point where wind and solar resources are completely interrupted, the control center (21) shuts down the secondary electric heater array and keeps only the primary electric heater array in standby mode.

9. The electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output according to claim 1, characterized in that: The steam supply unit consists of a high-temperature molten salt tank (2), a high-temperature molten salt pump (7) in the flow regulating device, a steam superheater (14), a steam generator (13), a water preheater (12), a water supply pump (16) in the flow regulating device, a water supply unit (15), a third molten salt regulating valve (19) in the flow regulating device, a water regulating valve (20) in the flow regulating device, and corresponding pipelines and power supply. During heating, the high-temperature molten salt pump (7) pumps high-temperature molten salt out of the high-temperature molten salt tank (2). After passing through the steam superheater (14), steam generator (13) and water preheater (12), the cooled low-temperature molten salt flows back to the low-temperature molten salt tank (1). Water is pumped out from the water supply unit (15) through the water supply pump (16), flows through the water preheater (12), steam generator (13) and steam superheater (14), absorbs the heat released by the molten salt and completes the preheating, vaporization and superheating processes in sequence, and finally forms high-temperature steam that meets the user's parameter requirements. Flexible control of the heating process can be achieved by adjusting the high-temperature molten salt pump (7), the third molten salt regulating valve (19), the water supply pump (16), and the water regulating valve (20).

10. An electrically heated molten salt thermal storage-heating system for rapidly absorbing fluctuations in wind and solar power output, as described in claim 1 or 3, characterized in that: The low-temperature molten salt tank (1) serves as a buffer unit for fluctuating power, using the molten salt inside the tank to buffer the temperature fluctuations of the molten salt entering the tank; the low-temperature molten salt tank (1) is filled with inert solid particles as a heat sink.

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