Fused salt heat storage and compressed air energy storage coupled coal power unit regulation and control method and system

Abstract

The invention discloses a coal power unit regulation and control method and system coupling fused salt heat storage and compressed air energy storage, and the method comprises the following steps: an energy storage stage: heating fused salt and compressed air energy storage by using redundant electric power of a coal power unit, and meanwhile, heating the fused salt by using compression heat generated in a high-temperature and high-pressure steam and compressed air energy storage process; in the energy release stage, the fused salt releases the stored heat, the heat is transferred to the coal power unit through the heat exchanger, and meanwhile, the compressed gas enters the expansion machine to do work after being heated by the heat exchanger to drive the coal power unit to generate power; and in the frequency modulation stage, a graded frequency modulation mode is determined based on the frequency difference between the real-time frequency and the rated frequency of the power grid, and the optimal power distribution scheme of the coal power unit, the fused salt heat storage and the compressed air energy storage in the frequency modulation process is determined by taking frequency modulation income maximization as an optimization target. The method can better adapt to the complex fluctuation of the power grid frequency, and the cooperation of the wide heat storage capacity and the high frequency modulation rate of the coal power unit is realized.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation unit coupled energy storage technology, and in particular to a coal-fired power generation unit control method and system that couples molten salt thermal storage and compressed air energy storage. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] The rapid development of new energy sources has had a significant impact on the safe and stable operation of the power grid, requiring the allocation of a large amount of flexible adjustment resources to achieve temporal and spatial decoupling of power supply and demand, and to ensure the security of power supply and demand.

[0004] Energy storage, as a flexible power regulation resource, utilizes media or devices to store excess energy in the form of electricity, heat, or chemical substances through chemical or physical means, and then releases it in a specific energy form according to application needs. On the power supply side, energy storage technology can work with thermal power units to regulate peak and frequency, smooth out fluctuations in renewable energy output, and has functions such as phase regulation, spinning reserve, and emergency response power generation. On the grid side, energy storage technology can support grid peak and frequency regulation, ensuring grid operation safety in the event of system failures or anomalies. On the user side, energy storage technology can provide users with comprehensive supply of cooling, heating, electricity, and gas while fully mobilizing the elasticity of load-side resources to support grid demand-side response.

[0005] Existing technologies disclose energy storage methods such as molten salt thermal energy storage and compressed air energy storage. However, while molten salt thermal energy storage has the advantage of strong peak-shaving capability, its frequency regulation capability is insufficient due to the thermal inertia of molten salt. Compressed air energy storage can directly store electrical energy, but its thermal storage capacity is limited. Therefore, coupling coal-fired power units with either molten salt thermal energy storage or compressed air energy storage alone presents the problem of difficulty in coordinating peak-shaving and frequency regulation. Even when coupling both energy storage methods simultaneously, the different response times and regulation rates of different energy storage systems raise the issue of how to optimize the allocation of frequency regulation tasks among the various energy storage systems during frequency regulation. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a coal-fired power unit regulation method and system that couples molten salt thermal storage and compressed air energy storage. By establishing a mathematical model to quantify frequency regulation benefits and operating costs, the optimal frequency regulation strategy that maximizes overall benefits and minimizes costs is found while meeting the grid frequency regulation requirements. At the same time, the hierarchical frequency regulation modes of the molten salt thermal storage system's individual response or its coordinated response with the compressed air energy storage system are clarified under different frequency difference ranges, thereby improving the economy and system stability of the frequency regulation process.

[0007] In some implementations, the following technical solutions are adopted: A method for regulating coal-fired power units that couples molten salt thermal storage with compressed air energy storage includes: During the energy storage phase, excess electricity from coal-fired power units is used to heat molten salt and compressed air for energy storage. At the same time, the heat of compression generated during the energy storage process of high-temperature and high-pressure steam and compressed air is also used to heat the molten salt. During the energy release phase, the molten salt releases the stored heat and transfers it to the coal-fired power unit through a heat exchanger. At the same time, the compressed gas is heated by the heat exchanger and enters the expander to do work, driving the coal-fired power unit to generate electricity. During the frequency regulation phase, the power grid frequency is monitored in real time. Based on the frequency difference between the real-time power grid frequency and the rated frequency, a tiered frequency regulation mode is determined. With the goal of maximizing frequency regulation benefits, an objective function is constructed. By solving the objective function, the optimal power allocation scheme for coal-fired power units, molten salt thermal storage, and compressed air energy storage during the frequency regulation process is determined.

[0008] As a further solution, a tiered frequency regulation mode is determined based on the frequency difference between the real-time frequency of the power grid and the rated frequency, specifically as follows: When the real-time frequency of the power grid deviates slightly from the rated frequency, that is, when the frequency difference between the real-time frequency of the power grid and the rated frequency is within the set first interval range, the molten salt thermal storage system is started and the compressed air energy storage is shut down, and the molten salt thermal storage system independently assists the coal-fired power unit in frequency regulation. When the real-time frequency of the power grid deviates significantly from the rated frequency, that is, when the frequency difference between the real-time frequency and the rated frequency falls within the set second interval range, the molten salt thermal storage system and the compressed air energy storage system are activated simultaneously, and the molten salt thermal storage system and the compressed air energy storage system jointly assist the coal-fired power unit in frequency regulation.

[0009] As a further option, the frequency difference range for frequency regulation of the independent auxiliary coal-fired power unit in the molten salt thermal storage system is (D, The frequency difference range for frequency regulation of coal-fired power units, jointly assisted by molten salt thermal storage system and compressed air energy storage system, is ( , Where D is the dead zone threshold corresponding to when the power grid frequency deviation exceeds the dead zone; and All are set values.

[0010] As a further approach, with maximizing frequency modulation revenue as the optimization objective, an objective function is constructed as follows: ; in, Frequency difference The moment when the dead zone threshold D is first exceeded is the frequency modulation start time; Frequency difference The moment when the frequency modulation ends is the moment when the frequency returns to the dead zone and remains stable within a set time. This refers to the change in active power during frequency regulation of coal-fired power units; This refers to the change in active power during the frequency regulation process of the molten salt thermal storage system. This refers to the change in active power during frequency regulation of the compressed air energy storage system. This is the frequency modulation revenue coefficient; This represents the corresponding operating cost penalty coefficient.

[0011] As a further embodiment, the objective function satisfies the hierarchical frequency modulation mode constraint, namely: when hour, ; when hour, .

[0012] As a further option, the molten salt thermal energy storage system can continuously provide industrial steam after the coal-fired power unit is shut down, serving as an emergency steam source and boiler start-up; the compressed air energy storage system can release air pressure and then extract heat from the turbine's regenerative system to obtain air with a set temperature and pressure that enters the turbine to expand and do work, thereby generating electricity and connecting to the grid.

[0013] As a further approach, the dynamic model of the coal-fired power unit is simplified to a combination of a governor and a turbine; wherein the transfer function of the governor is: ; The transfer function of the steam turbine component is: ; in, The gain of the speed controller; The time constant of the speed controller; The reheat time constant; The vapor volume time constant; This is the reheat coefficient; This represents the turbine gain coefficient.

[0014] In other embodiments, the following technical solutions are adopted: A coal-fired power unit control system coupling molten salt thermal storage and compressed air energy storage includes: The energy storage module is configured to use excess electricity from the coal-fired power unit to heat molten salt and compressed air for energy storage. At the same time, the heat of compression generated during the energy storage process of high-temperature and high-pressure steam and compressed air is also used to heat the molten salt. The energy storage module is configured to release the stored heat from the molten salt and transfer the heat to the coal-fired power unit through a heat exchanger. At the same time, the compressed gas is heated by the heat exchanger and enters the expander to do work, driving the coal-fired power unit to generate electricity. The frequency regulation module is configured to: monitor the grid frequency in real time, determine the graded frequency regulation mode based on the frequency difference between the real-time grid frequency and the rated frequency, construct an objective function with the goal of maximizing frequency regulation benefits, and determine the optimal power allocation scheme for coal-fired power units, molten salt thermal storage and compressed air energy storage during the frequency regulation process by solving the objective function.

[0015] In other embodiments, the following technical solutions are adopted: A terminal device includes a processor and a memory, the processor being used to implement instructions; the memory being used to store multiple instructions, the instructions being adapted to be loaded and executed by the processor to control the coal-fired power unit using the above-described method of coupled molten salt thermal storage and compressed air energy storage.

[0016] In other embodiments, the following technical solutions are adopted: A computer-readable storage medium storing a plurality of instructions adapted for loading and execution by a processor of a terminal device of the above-described method for controlling coal-fired power units that couples molten salt thermal storage and compressed air energy storage.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention couples a molten salt thermal energy storage system with a compressed air energy storage system. By dynamically optimizing the allocation of frequency regulation tasks, it fully utilizes the high heat capacity of molten salt thermal energy storage and the rapid response capability of compressed air energy storage, thereby improving the frequency regulation efficiency and stability of the unit. It not only optimizes the utilization rate of the energy storage system, but also enhances the overall performance of the unit, enabling it to better adapt to the complex fluctuations of the power grid frequency, and realizes the synergy between the wide thermal energy storage capacity and high frequency regulation rate of the coal-fired power unit.

[0018] (2) Based on the frequency difference range between the real-time frequency and the rated frequency of the power grid, the present invention divides the frequency regulation process into a slow frequency regulation interval and a fast frequency regulation interval. In the slow frequency regulation interval, the molten salt thermal storage system independently assists the coal-fired power unit in frequency regulation. In the fast frequency regulation interval, the compressed air energy storage system and the molten salt thermal storage system jointly assist the coal-fired power unit in frequency regulation, thereby realizing the graded coupling frequency regulation of the coal-fired power unit. As a result, the valves of the coal-fired power unit no longer open and close abruptly, the number of energy storage cycles is greatly reduced, the main steam pressure fluctuation is reduced, and the frequency regulation qualification rate is improved.

[0019] (3) Under the constraint of hierarchical coupling frequency regulation, the present invention constructs an objective function with the goal of maximizing frequency regulation benefits; then solves the optimal power allocation scheme of the coal-fired power unit coupled with molten salt thermal storage and compressed air energy storage system in the frequency regulation process; ensures that the system can efficiently complete the grid frequency regulation task and bring maximum economic benefits in the dynamic frequency regulation process, thereby improving the economy and system stability of the frequency regulation process.

[0020] Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a coal-fired power unit system that couples molten salt thermal storage and compressed air energy storage in an embodiment of the present invention; Figure 2 This is a flowchart of the coal-fired power unit control method that couples molten salt thermal storage and compressed air energy storage in an embodiment of the present invention; Figure 3 This is a schematic diagram of a coal-fired power unit staged coupling frequency regulation strategy that couples molten salt thermal storage and compressed air energy storage in an embodiment of the present invention; Among them, 1. Boiler, 2. Steam turbine, 3. Coal-fired power generator, 4. Compressor, 5. Expander, 6. Compressed air energy storage system generator, 7. High temperature molten salt tank, 8. Low temperature molten salt tank, 9. First heat exchanger, 10. Second heat exchanger, 11. Gas storage device. Detailed Implementation

[0022] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Example 1 In one or more embodiments, a method for regulating coal-fired power units that couples molten salt thermal storage with compressed air energy storage is disclosed, combining... Figure 2 This includes the following processes: During the energy storage phase, excess electricity from coal-fired power units is used to heat molten salt and compressed air for energy storage. At the same time, the heat of compression generated during the energy storage process of high-temperature and high-pressure steam and compressed air is also used to heat the molten salt. During the energy release phase, the molten salt releases the stored heat and transfers it to the coal-fired power unit through a heat exchanger. At the same time, the compressed gas is heated by the heat exchanger and enters the expander to do work, driving the coal-fired power unit to generate electricity. During the frequency regulation phase, the power grid frequency is monitored in real time. Based on the frequency difference between the real-time power grid frequency and the rated frequency, a tiered frequency regulation mode is determined. With the goal of maximizing frequency regulation benefits, an objective function is constructed. By solving the objective function, the optimal power allocation scheme for coal-fired power units, molten salt thermal storage, and compressed air energy storage during the frequency regulation process is determined.

[0025] As a specific implementation method. Figure 1 A schematic diagram of a coal-fired power unit system coupling molten salt thermal energy storage and compressed air energy storage is presented, specifically including: a coal-fired power unit, a molten salt thermal energy storage system, and a compressed air energy storage system. The coal-fired power unit mainly includes a boiler 1, a steam turbine 2, and a coal-fired power unit generator 3. The boiler generates high-temperature, high-pressure superheated steam, which is transported to the steam turbine through the main steam pipeline to perform work, thereby enabling the steam turbine to drive the generator to produce electricity. The molten salt thermal energy storage system includes a high-temperature molten salt tank 7, a low-temperature molten salt tank 8, a first heat exchanger 9, and a second heat exchanger 10. Both the first heat exchanger 9 and the second heat exchanger 10 are three-channel heat exchangers, capable of simultaneously accommodating the flow and heat exchange of three different media. The compressed air energy storage system includes a compressor 4, an expander 5, a compressed air energy storage system generator 6, an air storage device 11, and the molten salt thermal energy storage system; the molten salt thermal energy storage system replaces the heat exchange units in a traditional compressed air energy storage system.

[0026] (1) During the energy storage or peak-shaving phase, when the electricity demand is lower than the power generation of the coal-fired power units, the excess electricity can be used to heat the molten salt, or high-temperature and high-pressure steam can be used to heat the molten salt and store the heat. The molten salt maintains a stable heat storage state at high temperatures. At the same time, the compression heat generated during the compression process of the compressed air energy storage system can also enter the second heat exchanger to heat the molten salt. This part of the heat is stored in the high-temperature molten salt tank, and the compressed gas is stored in underground chambers, salt caverns, or gas storage tanks. The power used by the compressor can be directly taken from the plant's auxiliary power supply, which can further reduce the amount of electricity generated by the coal-fired power units.

[0027] Specifically, when renewable energy sources are abundant and the demand for grid power is low, coal-fired power units need to reduce their output. High-temperature, high-pressure steam (538℃, 3.8MPa) from the reheater outlet of boiler 1 transfers heat to low-temperature molten salt in the second heat exchanger 10. The low-temperature molten salt, at 200℃, absorbs heat energy at high temperature and stores it in the high-temperature molten salt tank 7. This portion of steam no longer enters the turbine 2 to perform work, thus reducing the power output of the coal-fired power unit's generator 3.

[0028] Meanwhile, in the compressed air energy storage system, after the expander stops working, the system's compressor 4 is started. The electricity consumed by the compressor can be counted as the plant's electricity consumption for the coal-fired power unit, further reducing the amount of electricity the coal-fired power unit generates to the grid. The compressor 4 compresses air into the air storage device 11 and transfers the heat of compression during the compression process to the low-temperature molten salt through the second heat exchanger 10.

[0029] The molten salt thermal storage temperature range is 200℃~400℃, and the storage time is 6 hours. In this specific implementation plan, a medium-temperature molten salt thermal storage system is selected.

[0030] (2) During the energy release / supply guarantee phase, when the electricity demand exceeds the power generation of the coal-fired power unit, the molten salt thermal storage system releases the stored heat and transfers it to the coal-fired power unit through a heat exchanger. The demineralized water from the deaerator outlet is heated by the first heat exchanger and then sent into the furnace to improve boiler efficiency. The coal-fired power unit can utilize this extra heat to increase power generation, thereby meeting the peak electricity demand. At the same time, the compressed gas in the gas storage device is heated by the three-channel heat exchanger and then enters the expander to do work, driving the generator to generate electricity, which can improve the system's supply guarantee capability.

[0031] Specifically, when the power grid needs additional electricity, the molten salt thermal storage system releases the stored heat energy. The high-temperature molten salt heats the condensate at the deaerator outlet through heat exchanger 9, increasing the feedwater temperature entering the furnace. This heat is then transferred to boiler 1, and the furnace feedwater temperature is raised to over 150°C after being heated by the heat exchanger.

[0032] Simultaneously, the compressed air in the compressed air energy storage system's storage device 11 also absorbs heat from the molten salt via the heat exchanger 9, raising its temperature from ambient temperature to over 100°C. It then enters the expander 5 to perform work, driving the compressed air energy storage system's generator 6 to generate electricity. This increases the overall power output of the coupled system. The heated compressed air can also be introduced into the furnace of the boiler 1 as primary or secondary air for combustion adjustment.

[0033] (3) During the frequency regulation phase, the grid frequency is monitored in real time and the unit output is dynamically adjusted. This embodiment adopts a graded coupling frequency regulation strategy. When the frequency deviates slightly from the set value, the molten salt thermal storage system independently assists the coal-fired power unit in frequency regulation; while when the frequency deviates significantly from the set value, the compressed air energy storage system and the molten salt thermal storage system jointly assist the coal-fired power unit in frequency regulation.

[0034] Different energy storage systems have different frequency response characteristics. For example, molten salt thermal energy storage systems have a fast response speed, low cost, and no minimum power threshold, while compressed air energy storage systems have a relatively slow response speed and high cost. Therefore, in this embodiment, when the frequency deviates slightly from the set value (which often occurs at a high frequency and for a long duration), using only the molten salt thermal energy storage system to independently assist the coal-fired power unit for frequency regulation can meet the system's frequency regulation requirements at a low cost. However, when the frequency deviates significantly from the set value (which often occurs at a low frequency and for a short duration), adding a compressed air energy storage system for auxiliary frequency regulation can achieve better frequency regulation results. At the same time, it can avoid frequent start-stop and idling of the compressed air energy storage system, which would accelerate equipment fatigue. This achieves a better overall effect in terms of equipment life, energy consumption, and revenue.

[0035] Specifically, in the event of external disturbances In existence, the real-time frequency of the power grid This will cause fluctuations, which will then affect the rated frequency. Frequency difference between The frequency difference is expressed as: .

[0036] Given the different frequency modulation requirements, the frequency modulation process can be divided into a slow frequency modulation range and a fast frequency modulation range, which are represented by frequency modulation range 1 and frequency modulation range 2, respectively: FM band 1: ; FM band 2: ; Where D is the threshold corresponding to the frequency dead zone, that is, when the frequency difference exceeds the threshold D, frequency regulation is initiated. For coal-fired power units, the value of D is generally 0.033 Hz. The maximum threshold for the individual response of a molten salt thermal storage system; The maximum threshold for frequency regulation involving both compressed air energy storage systems and molten salt thermal energy storage systems. and These are all set values, which can be adjusted according to actual needs.

[0037] As a concrete example, the frequency difference threshold and We can take 0.2 Hz and 0.3 Hz respectively, then frequency modulation interval 1 and frequency modulation interval 2 can be expressed as: FM band 1: ; FM band 2: .

[0038] Figure 3 A schematic diagram of the transfer function of a staged coupled frequency regulation strategy for coal-fired power units that couples molten salt thermal storage and compressed air energy storage is presented.

[0039] For steam turbine equipment, if its dynamic characteristics are modeled using differential equations, a high-order differential equation system involving multiple coupled variables such as speed deviation, steam flow rate, and power output needs to be established. For example: ,in, For mechanical torque, Electromagnetic torque involves multiple state variables and parameters, making it too complex to analyze directly.

[0040] In this embodiment, considering the actual application scenario, the dynamic model of the coal-fired power unit was simplified: the transfer function of the coal-fired power unit was abstracted into a combination of the governor and the turbine, thereby reducing the complexity of the model while retaining the core dynamic characteristics.

[0041] The transfer function of the speed governor component is: ; The transfer function of the steam turbine component is: ; in, The gain of the speed controller; The time constant of the speed controller; The reheat time constant; The vapor volume time constant; This is the reheat coefficient; This represents the turbine gain coefficient.

[0042] The dynamic model of the molten salt thermal energy storage system is simplified to a combination of a molten salt heat exchanger, a molten salt pump, and a molten salt storage tank; the transfer function of the molten salt heat exchanger is: ; The transfer function of the molten salt pump is: ; The transfer function for the molten salt storage tank is: ; in, The time constant for heat transfer, The time constant of the molten salt pump. This refers to a molten salt storage tank, reflecting the impact of the amount of molten salt stored in the tank on the dynamic characteristics of the system.

[0043] The dynamic model of the compressed air energy storage system is simplified to a combination of a compressor, an expander, and an air storage unit; the transfer function of the compressor is: ; The transfer function of the expander is: ; The transfer function of the gas storage unit is: ; in, This is the load adjustment effect coefficient. The time constant of the expander This refers to the capacity of the gas storage unit.

[0044] Frequency modulation of the coupled system adopts a regional equivalent machine frequency modulation model, and its transfer function can be expressed as: ; in, This is the load adjustment effect coefficient; is the inertial time constant.

[0045] This embodiment constructs a transfer function model for the coal-fired power unit, molten salt thermal storage, and compressed air energy storage system. This model provides a mathematical description of the "system response characteristics" for the "dynamic power allocation" during the frequency regulation phase. Specifically, it predicts the actual output response of each subsystem (coal-fired power unit, molten salt, and compressed air) under different power commands; it constrains the "power change rate" and "response lag" in the optimization solution process to avoid infeasible allocation schemes or overshoot; and it supports the implicit evaluation of "frequency regulation accuracy" and "response speed" in the objective function.

[0046] When performing specific frequency regulation tasks, dynamic allocation of regulation power is necessary to maximize benefits. Without optimized allocation, energy storage systems with slow response times, low accuracy, or low energy conversion efficiency may bear excessive frequency regulation tasks. This can lead to an inability to track grid frequency changes in a timely manner, failing to accurately meet grid frequency regulation needs, and resulting in ineffective suppression of grid frequency fluctuations, impacting grid stability and power quality. Furthermore, more energy may be wasted during conversion, reducing the overall energy utilization efficiency of the energy storage system and increasing operating costs. Additionally, some energy storage systems may operate under high load and high loss conditions for extended periods, while others are underutilized. This can cause premature aging and damage to some equipment due to overuse, increasing maintenance costs and replacement frequency, shortening the overall lifespan of the energy storage system, and reducing its economic efficiency and reliability.

[0047] Therefore, this embodiment takes maximizing frequency regulation benefits as the optimization objective, constructs an objective function, and determines the optimal power allocation scheme for coal-fired power units, molten salt thermal storage, and compressed air energy storage during the frequency regulation process by solving the objective function.

[0048] As a specific implementation method, the objective function is as follows: ; in, Frequency difference The moment when the dead zone threshold D is first exceeded is the frequency modulation start time; Frequency difference The moment when the frequency modulation ends is the moment when the frequency returns to the dead zone and remains stable within a set time. This refers to the change in active power during frequency regulation of coal-fired power units; This refers to the change in active power during the frequency regulation process of the molten salt thermal storage system. This refers to the change in active power during frequency regulation of the compressed air energy storage system. This is the frequency modulation revenue coefficient; This is the corresponding operating cost penalty coefficient; and These are all empirical coefficients, which are set values.

[0049] The specific constraints are as follows: (1) System frequency modulation characteristic constraints: ; in, This represents the change in active power during the overall frequency regulation process of the coupled system.

[0050] (2) Constraints of hierarchical frequency modulation mode: when hour, ; when hour, .

[0051] (3) Power change rate constraint: ; ; .

[0052] in, , , These are the active power during the frequency regulation process of coal-fired power units, molten salt thermal storage systems, and compressed air energy storage systems, respectively. This is the maximum power regulation rate of the coal-fired power unit itself; This is the maximum power regulation rate of the molten salt thermal storage system itself; This is the maximum power regulation rate of the compressed air energy storage system itself.

[0053] In solving the above objective function, the upper limit of the power change rate of each subsystem is... , and It can be derived by inversely from the time constant of its corresponding transfer function.

[0054] By solving the objective function, the optimal power allocation scheme of the coal-fired power unit coupled with molten salt thermal storage and compressed air energy storage system during frequency regulation is obtained. Under different grid frequency difference conditions (slight or severe deviation from the rated frequency), the required frequency regulation power of the coal-fired power unit, molten salt thermal storage system and compressed air energy storage system is determined to maximize frequency regulation benefits and minimize operating costs. At the same time, the constraints of the graded frequency regulation mode (such as the molten salt thermal storage system responding alone or in coordination with the compressed air energy storage system) are met, ensuring that the system can efficiently complete the grid frequency regulation task and bring maximum economic benefits during dynamic frequency regulation.

[0055] This embodiment quantifies the frequency regulation benefits and operating costs by establishing a mathematical model. Under the premise of meeting the grid frequency regulation requirements, it finds the optimal frequency regulation strategy that maximizes the overall benefits and minimizes the costs. At the same time, it clarifies the graded frequency regulation modes of the molten salt thermal storage system responding alone or in coordination with the compressed air energy storage system under different frequency difference ranges, thereby improving the economy and system stability of the frequency regulation process.

[0056] As an optional implementation, when coal-fired power units are shut down or cannot meet steam supply demands under low-load conditions, low-temperature steam can absorb heat from molten salt through a heat exchanger to increase temperature and pressure parameters, and then be transported out as steam for industrial or residential heating.

[0057] The control system monitors grid load and power generation demand, determines when to release stored energy, ensures coordinated operation with coal-fired power units, and improves system efficiency and response speed. By optimizing power generation efficiency, it reduces peak electricity purchase costs, lowers operating costs, and minimizes environmental impact. Through more efficient utilization of energy generated by coal-fired power units and energy storage systems, it reduces carbon emissions and enhances the sustainability of the power system. This embodiment effectively couples coal-fired power units with energy storage systems (molten salt thermal storage and compressed air energy storage) to improve energy utilization efficiency, reduce costs, and minimize environmental impact, meeting the high efficiency and environmental protection requirements of modern power networks.

[0058] Example 2 In one or more embodiments, a coal-fired power unit control system coupling molten salt thermal storage and compressed air energy storage is disclosed, comprising: The energy storage module is configured to use excess electricity from the coal-fired power unit to heat molten salt and compressed air for energy storage. At the same time, the heat of compression generated during the energy storage process of high-temperature and high-pressure steam and compressed air is also used to heat the molten salt. The energy storage module is configured to release the stored heat from the molten salt and transfer the heat to the coal-fired power unit through a heat exchanger. At the same time, the compressed gas is heated by the heat exchanger and enters the expander to do work, driving the coal-fired power unit to generate electricity. The frequency regulation module is configured to: monitor the grid frequency in real time, determine the graded frequency regulation mode based on the frequency difference between the real-time grid frequency and the rated frequency, construct an objective function with the goal of maximizing frequency regulation benefits, and determine the optimal power allocation scheme for coal-fired power units, molten salt thermal storage and compressed air energy storage during the frequency regulation process by solving the objective function.

[0059] The specific implementation methods of the above modules are the same as those in Example 1, and will not be described in detail again.

[0060] Example 3 In one or more embodiments, a terminal device is disclosed, comprising a processor and a memory, wherein the processor is used to implement instructions; and the memory is used to store multiple instructions adapted to be loaded by the processor and executed by the processor to control the coal-fired power unit using the coupled molten salt thermal storage and compressed air energy storage method of Embodiment 1.

[0061] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0062] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0063] In the implementation process, each step of the above method can be completed by the integrated logic circuits in the processor hardware or by software instructions.

[0064] Example 4 In one or more embodiments, a computer-readable storage medium is disclosed, wherein a plurality of instructions are stored, the instructions being adapted to be loaded by a processor of a terminal device and executed by the coal-fired power unit control method of coupled molten salt thermal storage and compressed air energy storage in Embodiment 1.

[0065] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A coal power unit regulation method coupling molten salt thermal energy storage and compressed air energy storage, characterized in that, The method comprises: a storage stage, in which the excess power of the coal-fired unit is used to heat molten salt and compressed air energy storage, and the compression heat generated in the high-temperature and high-pressure steam and compressed air energy storage process is also used to heat the molten salt; a release stage, in which the molten salt releases the stored heat, the heat is transferred to the coal-fired unit through a heat exchanger, and compressed gas heated by the heat exchanger enters an expander to do work and drive the coal-fired unit to generate electricity; a frequency regulation stage, in which the real-time frequency of the power grid is monitored, a hierarchical frequency regulation mode is determined based on the difference between the real-time frequency and the rated frequency of the power grid, a target function is constructed with the maximization of frequency regulation benefits as an optimization target, and the optimal power distribution scheme of the coal-fired unit, the molten salt heat storage and the compressed air energy storage in the frequency regulation process is determined by solving the target function.

2. The method for regulating a coal-fired power unit coupled with molten salt thermal storage and compressed air energy storage as described in claim 1, characterized in that, The hierarchical frequency regulation mode is determined based on the difference between the real-time frequency and the rated frequency of the power grid, and specifically: when the real-time frequency of the power grid slightly deviates from the rated frequency, i.e., when the difference between the real-time frequency and the rated frequency of the power grid belongs to a set first interval range, the molten salt heat storage system is started and the compressed air energy storage is turned off, and the molten salt heat storage system independently assists the coal-fired unit to regulate frequency; when the real-time frequency of the power grid seriously deviates from the rated frequency, i.e., when the difference between the real-time frequency and the rated frequency of the power grid belongs to a set second interval range, the molten salt heat storage system and the compressed air energy storage system are started at the same time, and the molten salt heat storage system and the compressed air energy storage system jointly assist the coal-fired unit to regulate frequency.

3. The method of claim 1, wherein the coal power unit is coupled with a molten salt thermal storage and compressed air energy storage system. The frequency difference range of the molten salt heat storage system independently assisting the coal-fired power unit for frequency modulation is (D, ] The frequency difference range of the molten salt heat storage system and the compressed air energy storage system jointly assisting the coal-fired power unit for frequency modulation is (D , ] wherein D is a dead zone threshold corresponding to when the grid frequency deviation exceeds the dead zone, and are set values.

4. The method of claim 1, wherein the coal power unit is coupled with a molten salt thermal storage and compressed air energy storage system. The target function is constructed with the maximization of frequency regulation benefits as an optimization target, and specifically: ； wherein, is the frequency difference is the time when the frequency modulation starts, which is the time when the frequency first exceeds the dead-band threshold D; is the frequency difference is the time when the frequency modulation ends, which is the time when the frequency returns to the dead-band range and remains stable within the set time; is the active power variation during the frequency modulation of the coal-fired unit; is the active power variation during the frequency modulation of the molten salt thermal storage system; is the active power variation during the frequency modulation of the compressed air energy storage system; is the frequency modulation benefit coefficient; is the corresponding operation cost penalty coefficient.

5. The method for regulating a coal-fired power unit coupled with molten salt thermal storage and compressed air energy storage as described in claim 4, characterized in that, The target function satisfies the hierarchical frequency regulation mode constraint, i.e.: When Time, ; When time, .

6. The method of claim 1, wherein the coal power plant is coupled with a molten salt thermal storage and compressed air energy storage system. The molten salt heat storage system can continuously provide industrial steam after the coal-fired unit is shut down, as an emergency steam source and a starting boiler; the compressed air energy storage system can release air pressure, take heat from a steam turbine heat recovery system, obtain air with a set temperature and pressure, and enter a turbine to expand and do work to realize power generation and grid connection.

7. The method of claim 1, wherein the coal power plant is coupled with a molten salt thermal storage and compressed air energy storage system. The dynamic model of the coal-fired unit is simplified as a combination of a speed regulator link and a steam turbine link; the transfer function of the speed regulator link is: ； The transfer function of the steam turbine link is: ； wherein, is the gain of the governor; is the time constant of the governor; is the reheat time constant; is the steam volume time constant; is the reheat factor; is the gain factor of the steam turbine.

8. A coal power unit regulation system coupled with molten salt thermal storage and compressed air energy storage, characterized in that, The method comprises: a storage module configured to heat molten salt and compressed air energy storage using excess power of the coal-fired unit, and the compression heat generated in the high-temperature and high-pressure steam and compressed air energy storage process is also used to heat the molten salt; a storage module configured to release the heat stored by the molten salt, transfer the heat to the coal-fired unit through a heat exchanger, and heat compressed gas through the heat exchanger, and then the compressed gas enters an expander to do work and drive the coal-fired unit to generate electricity; a frequency regulation module configured to monitor the real-time frequency of the power grid, determine a hierarchical frequency regulation mode based on the difference between the real-time frequency and the rated frequency of the power grid, construct a target function with the maximization of frequency regulation benefits as an optimization target, and determine the optimal power distribution scheme of the coal-fired unit, the molten salt heat storage and the compressed air energy storage in the frequency regulation process by solving the target function. 9.A terminal device comprising a processor and a memory, the processor configured to implement instructions; the memory configured to store a plurality of instructions, the terminal device characterized in that, The instructions are suitable for being loaded and executed by the processor to perform the coal-fired unit regulation and control method coupling molten salt heat storage and compressed air energy storage according to any one of claims 1-7.

10. A computer-readable storage medium having stored therein a plurality of instructions, wherein the instructions, when executed by a processor, cause the processor to perform operations comprising: The instructions are adapted to be loaded and executed by a processor of a terminal device to perform the coal power unit regulation method coupling molten salt heat storage and compressed air energy storage according to any one of claims 1-7.

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