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CN-121994053-A - Electric heating molten salt heat storage-supply system for rapidly absorbing wind-light output fluctuation

CN121994053ACN 121994053 ACN121994053 ACN 121994053ACN-121994053-A

Abstract

The invention relates to an electric heating molten salt heat storage-supply system for rapidly absorbing wind-solar output fluctuation, which comprises a low-temperature molten salt tank, a high-temperature molten salt tank, a multi-stage electric heater array, a molten salt pump, a regulating valve, a switching valve, a temperature measuring point, a preheater, an evaporator, a superheater, a water supply pump, a water supply unit and matched pipelines. The system adopts hierarchical control that a primary electric heater array runs at constant flow in set time to respond to power fluctuation from a second level to a minute level, and a secondary electric heater array responds to power fluctuation from the minute level to an hour level by adjusting molten salt flow and stabilizes the molten salt outlet temperature. In the occasion that needs the strict control high temperature fused salt temperature, the system can ensure the high temperature fused salt temperature quality through adding the fused salt return circuit. The heat sink effect of the molten salt in the low-temperature molten salt tank can effectively buffer temperature abrupt change and stabilize the flow field. The invention can continuously output qualified high-temperature molten salt under the input of high-fluctuation electric energy and stably supply steam.

Inventors

  • Chen Biduan
  • XIAO LIYE
  • LI XIN
  • ZHANG QIANGQIANG

Assignees

  • 中国科学院电工研究所

Dates

Publication Date
20260508
Application Date
20260126

Claims (10)

  1. 1. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and light output fluctuations, comprising: A low-temperature molten salt tank (1) for storing low-temperature molten salt; a high-temperature molten salt tank (2) for storing high-temperature molten salt; the multistage heater array comprises at least one stage of electric heater array (3) and a second stage of electric heater array (4) and is used for eliminating new energy output, converting electric energy into heat energy and transmitting the heat energy to molten salt; A first low-temperature molten salt pump (5) and a second low-temperature molten salt pump (6) which are positioned in the low-temperature molten salt tank and are used for pumping low-temperature molten salt from the low-temperature molten salt tank (1); a high-temperature molten salt pump (7) which is positioned in the high-temperature molten salt tank and is used for pumping high-temperature molten salt from the high-temperature molten salt tank (2); a flow rate adjusting device for adjusting the flow rate of the fluid; the switch valve is arranged on a pipeline between the heater and the high-temperature molten salt tank and is used for controlling the flow direction of molten salt; The first temperature measuring point (8) and the second temperature measuring point (9) are used for feeding back temperature signals to control molten salt flow and the direction of the steering valve; A steam supply unit for producing high temperature steam using heat of the high temperature molten salt; The control center (21) is used for distributing the power of the electric heater arrays at all levels; The matched pipeline is used for connecting the components; When new energy is consumed, the control center (21) is configured to distribute high fluctuation electric energy of new energy output to the first-stage electric heater array (3) and distribute reference power components of new energy output to the second-stage electric heater array (4), low-temperature molten salt in the low-temperature molten salt tank (1) is pumped to the first-stage electric heater array (3) and the second-stage electric heater array (4) for heating, the molten salt heated by the first-stage electric heater array (3) returns to the low-temperature molten salt tank (1), the molten salt heated by the second-stage electric heater array (4) enters the high-temperature molten salt tank (2), and when heat is supplied, the high-temperature molten salt is pumped 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 heat release.
  2. 2. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 1 wherein: The control center (21) is configured to decompose the new energy output into a high fluctuation power component and a reference power component, and distribute the high fluctuation power component to the primary electric heater array (3), and the reference power component to the secondary electric heater array (4); The high fluctuation power component has the characteristics of rapid fluctuation and high frequency change within 1 second to 20 minutes, the reference power component has the characteristics of continuous characteristic and low frequency change of tens of minutes to hours, and the time scale of power distribution can be set according to specific application scenes; The method for distributing power by the control center (21) comprises the steps of decomposing new energy output into the high fluctuation power component and the reference power component through power prediction and a signal decomposition algorithm based on variation mode decomposition or empirical mode decomposition based on historical operation data and wind-light resource prediction; The distribution strategy can be dynamically adjusted according to the quarterly change and the fluctuation characteristic of the wind and light resources; The power distribution method further comprises the steps of dynamically adjusting the power distribution proportion of the primary electric heater array and the secondary electric heater array according to the output prediction result and by combining the real-time running state of the system, so that accurate consumption of high-fluctuation electric energy is realized; The power distribution method is also coordinated with the power capacities of the primary and secondary electric heater arrays to ensure that the distribution strategy is effectively implemented within the operational safety range of the device.
  3. 3. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 1 wherein: The low-temperature molten salt tank (1), the first low-temperature molten salt pump (5), a first molten salt regulating valve (17) in the flow regulating device, the primary electric heater array (3) and corresponding pipelines and power supplies form an instantaneous power absorption unit within 1 second to 20 minutes, wherein the time scale of power distribution can be set according to specific application scenes; the power capacity configuration of the primary electric heater array covers the maximum value of the local new energy output fluctuation; the low-temperature molten salt tank (1) is used for storing low-temperature molten salt and storing the molten salt heated by the primary electric heater array and the molten salt from the high-temperature molten salt loop; The cryogenic molten salt tank (1) is configured to rely on the inventory heat capacity in the cryogenic molten salt tank to suppress in-tank temperature fluctuations; molten salt is pumped out from the bottom of the low-temperature molten salt tank, and enters the tank from the top of the molten salt tank; The high flow ensures that molten salt fully exchanges heat in the electric heater, so that the primary electric heater array can directly and quickly respond to high-frequency fluctuation power without depending on response delay of flow regulation, thereby meeting fluctuation absorption requirements in 1 second to 20 minutes, wherein the time scale of power distribution can be set according to specific application scenes; The set time and the maximum molten salt flow are matched with a typical high-frequency fluctuation period of local wind-solar power, and the periodic adjustment is carried out through a first low-temperature molten salt pump (5) and a first molten salt regulating valve (17) in the flow control device.
  4. 4. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 1 wherein: The high-temperature molten salt tank (2), the second low-temperature molten salt pump (6), a second molten salt regulating valve (18) in the flow regulating device, a secondary electric heater array (4), a first temperature measuring point (8) and a second temperature measuring point (9), a main circuit switching valve (10) and a loop switching valve (11), and corresponding pipelines and power supplies form a reference power absorption unit of tens of minutes to hours; When the distributed power changes, the control center (21) adjusts the molten salt flow 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 relation, so that the molten salt outlet temperature of the secondary electric heater array (4) is stabilized in a preset range.
  5. 5. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 1,3 or 4 wherein: the composition mode of the primary and/or secondary electric heater array comprises at least one of the following components: consists of N electric heaters which are connected in series, wherein N is more than or equal to 1, and N is an integer; consists of N electric heaters which are connected in parallel, wherein N is more than or equal to 1, and N is an integer; The electric heater is composed of N electric heaters in a series and parallel mixed mode, wherein N is more than or equal to 1, and N is an integer; The electric heater array is powered by a matched power supply system, and the matched power supply system is directly connected with the new energy power generation system; in the parallel or hybrid connection mode, rated powers of the electric heater branches can be independently configured and are identical or different from each other; each electric heating branch is correspondingly provided with an independent flow regulating valve for respectively controlling the flow of molten salt flowing through each branch; By coordinately controlling the power and the molten salt flow of each branch, the system can realize quick response and flexible adjustment on the fluctuation of the new energy output.
  6. 6. The electric heating molten salt heat storage-supply system for rapidly absorbing wind-solar output fluctuation according to claim 4 is characterized in that the heated molten salt is directly conveyed to a high-temperature molten salt tank when the high-temperature molten salt temperature is not required to be strictly controlled, 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 additionally arranged on a pipeline between the downstream of the secondary electric heater array (4) and the upstream of the high-temperature molten salt tank (2) when the high-temperature molten salt temperature is required to be strictly controlled, and the pipeline is provided with a first temperature measuring point (8) and a main circuit switching valve (10) and a loop switching valve (11) in the valve device; When the high-temperature molten salt temperature needs to be strictly controlled, the molten salt temperature flowing through the pipeline is monitored in real time through the first temperature measuring point (8), and when the system encounters power dip to cause the molten salt temperature to be lower than the admission temperature of the high-temperature molten salt tank (2), the loop switch valve (11) is opened and the main switch valve (10) is synchronously closed, so that the molten salt which does not reach the temperature returns to the low-temperature molten salt tank (1) directly through the return pipeline, and the molten salt temperature in the high-temperature molten salt tank (2) is ensured to be stable within a required range.
  7. 7. The electric heating molten salt heat storage-supply system for rapidly absorbing wind-solar output fluctuation according to claim 1, wherein the fluctuation absorbing method comprises a power sudden rise absorbing strategy and a power sudden drop absorbing strategy: When transient power rises suddenly: when the power fluctuation range is within the rated power coverage range of the primary electric heater array and lasts for 1 second to 20 minutes, the power fluctuation range is singly and quickly absorbed by the primary electric heater array; When the power fluctuation amplitude exceeds the rated power of the primary electric heater array and lasts for 1 second to 20 minutes, in a safety threshold, preferentially distributing power to the primary electric heater array, synchronously increasing the power distribution proportion of the secondary electric heater array to cooperatively consume excessive fluctuation power, immediately rapidly increasing the molten salt flow of the secondary electric heater array to a high-level value, taking the rapid consumption instantaneous fluctuation power as a core target for flow regulation at the stage, after the power fluctuation falls back into the rated power range of the primary electric heater array, downwards regulating the molten salt flow of the secondary electric heater array by a control center to be matched with the current reference power again, and in a scene of needing to strictly control the temperature of high-temperature molten salt, closing a main switching valve (10) and opening a loop switching valve (11) through the high-temperature molten salt reflux pipeline of claim 6 during fluctuation, so that the molten salt returns from the pipeline to the low-temperature molten salt tank; When the power is greatly increased and lasts for tens of minutes to several hours, the primary electric heater array and the secondary electric heater array are simultaneously adjusted, namely, the power of the primary electric heater array is firstly increased to the safe operation upper limit of the primary electric heater array to maximally absorb transient fluctuation components, then the control center redistributes rated power share of the secondary electric heater array according to the reference power requirement after power stabilization, adjusts the fused salt flow according to a preset fused salt power-flow curve to ensure that the fused salt temperature at the outlet of the secondary electric heater array is stabilized in a set range, simultaneously reduces the power load of the primary electric heater array, and finally enables the primary electric heater array to return to a preset working state for absorbing high-frequency fluctuation.
  8. 8. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 7 wherein: when transient power dips: When the power fluctuation range is within the range of the adjusting capacity of the primary electric heater array and lasts for 1 second to 20 minutes, the transient fluctuation is quickly absorbed by the primary electric heater array by adjusting the power of the primary electric heater array, wherein the time scale of power distribution can be set according to specific application scenes; when the reference power component synchronously drops due to the power dip and recovers within 20 minutes, a control center (21) maintains the current molten salt flow of the secondary electric heater array unchanged, and for a scene with high molten salt outlet temperature requirement, molten salt which does not reach the set temperature after being heated by the secondary electric heater array (4) returns to the low-temperature molten salt tank (1) through the high-temperature molten salt return pipeline in claim 6 to be heated again; when the power dip amplitude is overlarge and lasts for tens of minutes to several hours, the control center (21) synchronously reduces the electric heating power of the secondary electric heater array, correspondingly reduces the molten salt flow according to a preset molten salt power-flow curve, and enables the output power and the input power of the system to be matched again; When the power continuously drops to the point that the wind and light resources are completely interrupted, the control center (21) turns off the secondary electric heater array, and only the primary electric heater array is kept in a standby state.
  9. 9. An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations as defined in claim 1 wherein: The steam supply unit is composed 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, corresponding pipelines and a matched power supply; When heating, the high-temperature molten salt pump (7) pumps out the high-temperature molten salt from the high-temperature molten salt tank (2), the high-temperature molten salt flows back to the low-temperature molten salt tank (1) after passing through the steam superheater (14), the steam generator (13) and the water preheater (12), and water is pumped out from the water supply unit (15) through the water supply pump (16) and flows through the water preheater (12), the steam generator (13) and the steam superheater (14) to absorb the heat released by the molten salt to sequentially complete the preheating, vaporizing and overheating processes, so that high-temperature steam meeting the requirements of user parameters is finally formed; The high-temperature molten salt pump (7), the third molten salt regulating valve (19), the water feeding pump (16) and the water regulating valve (20) are regulated, so that flexible control of the heating process is realized.
  10. 10. The electric heating fused salt heat storage-supply system for rapidly absorbing wind-solar output fluctuation is characterized in that the low-temperature fused salt tank (1) is used as a buffer unit for fluctuation power, fused salt in the tank is used for buffering fused salt temperature fluctuation entering the tank, and inert solid particles are filled in the low-temperature fused salt tank (1) to be used as heat sinks.

Description

Electric heating molten salt heat storage-supply system for rapidly absorbing wind-light output fluctuation Technical Field The invention relates to the field of energy storage, in particular to an electric heating molten salt heat storage-supply system for rapidly absorbing wind-light output fluctuation. Background The output of new energy sources such as wind power, photovoltaic and the like has randomness, volatility and intermittence, and brings remarkable challenges to the power balance of a power grid, so that the problems of wind abandoning and light abandoning are outstanding. Meanwhile, the terminal heat energy supply still mainly depends on fossil energy, and the carbon reduction pressure is high. The terminal heat energy supply still mainly depends on fossil energy sources, and the carbon reduction pressure is remarkable. The new energy power is converted into heat energy, so that the decarburization pressure of the thermodynamic department can be relieved, and the new energy power absorbing capacity can be improved. Therefore, the new energy is pushed to be converted into heat energy in situ, not only is the flexible load provided for the power system enhanced, but also the heat cost of industrial users can be reduced, and the method is particularly suitable for industrial scenes with stable and continuous heat requirements. However, there is a source-load mismatch between the new energy output and the industrial heat load. In order to realize decoupling and time period transfer of electric-thermal energy, a heat storage system becomes a key link. Among them, the electric heating molten salt heat storage technology is one of the effective modes for realizing energy translation and power smoothing. The technology is mainly applied to a scene with a large power grid or a stable power supply support at present. With the continuous improvement of the permeability of renewable energy sources and the development of novel energy consumption modes such as a zero-carbon park, an off-grid system, isolated grid operation and the like, the proportion of independent energy supply scenes without large grid support is gradually increased. In such a scenario, the electric heating molten salt heat storage system needs to cope with power fluctuation from new energy, and higher requirements are put on dynamic response capability, robustness and regulation precision of the system. Because the fluctuation range of new energy output is large, the electric heating fused salt heat storage system in the existing scene is difficult to rapidly eliminate the sudden change power from nanosecond level to minute level, and the overtemperature damage of the electric heater or the unqualified fused salt temperature are easy to cause. Therefore, how to realize rapid power response, flexible regulation and continuous stable heat supply of the heat storage module under the condition of severe fluctuation of source end power has become a current important task. Disclosure of Invention In order to solve the technical problems, the invention provides an electric heating molten salt heat storage-supply system for rapidly absorbing wind-light output fluctuation. In order to achieve the above purpose, the invention adopts the following technical scheme: An electrically heated molten salt heat storage-supply system for rapidly absorbing wind and solar power output fluctuations, comprising: the low-temperature molten salt tank is used for storing low-temperature molten salt; The high-temperature molten salt tank is used for storing high-temperature molten salt; the multi-stage heater array comprises at least one stage of electric heater array and at least one stage of electric heater array, and is used for eliminating new energy output, converting electric energy into heat energy and transmitting the heat energy to molten salt; the first low-temperature molten salt pump and the second low-temperature molten salt pump are positioned in the low-temperature molten salt tank and are used for pumping low-temperature molten salt from the low-temperature molten salt tank; The high-temperature molten salt pump is positioned in the high-temperature molten salt tank and is used for pumping high-temperature molten salt from the high-temperature molten salt tank; the switch valve is arranged on a pipeline between the heater and the high-temperature molten salt tank and is used for controlling the flow direction of molten salt; The first temperature measuring point and the second temperature measuring point are used for feeding back temperature signals to control molten salt flow and the direction of the steering valve; A steam supply unit for producing high temperature steam using heat of the high temperature molten salt; The control center is used for distributing the power of the electric heater arrays at all levels; The matched pipeline is used for connecting the components; When new energy is consumed, the control center is configured to distribu