Compressed air energy and gas storage capacity and inflation and deflation rate determination method and system based on thermodynamic response differential decomposition

Abstract

The invention provides a method and system for determining the storage capacity and the inflation and deflation rate of a compressed air energy storage gas storage based on thermodynamic response differential decomposition, and the method comprises the steps: building a gas storage thermodynamic response differential model, and determining the storage capacity and the inflation and deflation rate of the compressed air energy storage gas storage based on the gas storage thermodynamic response differential model; the maximum pressure which can be stored in the gas storage and the maximum pressure reached by air in the gas storage are obtained; isolines of the maximum pressure and the maximum pressure are drawn on a reservoir capacity-inflation and deflation rate two-dimensional plane, feasible design values of the reservoir capacity and the inflation and deflation rate meeting storage and pressure constraints at the same time are determined through the intersection point of the two isolines, and optimization design of the compressed air energy and gas storage reservoir is completed. According to the technical scheme, an efficient and accurate theoretical tool is provided for CAES gas storage design.

Description

Technical Field

[0001] This invention belongs to the field of compressed air energy storage (CAES) technology, specifically relating to a method and system for determining the storage capacity and inflation / deflation rate of a compressed air energy storage tank based on thermodynamic response differential decomposition. Background Technology

[0002] Compressed air energy storage (CAES) is a large-scale, long-term energy storage technology that plays a crucial role in mitigating the impact of new energy grid integration and enhancing grid stability. Underground gas storage facilities, such as rock-lined caverns or salt caverns, are the core components of a CAES system. During the preliminary design phase of a CAES power plant, rapidly and accurately estimating the required storage volume (storage capacity) and the charging / discharging rates (charging / discharging rates) is essential, as these directly affect the system's energy storage capacity, power output, economy, and safety.

[0003] In existing technologies, estimating storage capacity and gas filling / discharging rates largely relies on numerical simulation methods. Numerical simulation methods are computationally complex and time-consuming, and require a high level of expertise from the user, making them unsuitable for rapid engineering design and scheme comparison. Furthermore, existing methods lack a universal design tool that can intuitively and systematically link design objectives (such as rated storage capacity and maximum allowable operating pressure) directly to the two key design parameters: storage capacity and gas filling / discharging rate. Therefore, there is an urgent need for a method that considers actual thermodynamic processes (non-adiabatic conditions), is easy to apply in engineering, and can quickly and accurately determine the storage capacity and gas filling / discharging rate of a CAES gas storage facility. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention discloses a method and system for determining the capacity and inflation / deflation rate of compressed air energy storage (especially rock-lined caverns (LRCs) or salt caverns) based on thermodynamic response differential decomposition, providing an efficient and accurate theoretical tool for CAES storage design.

[0005] To achieve the above objectives, the present invention provides the following solution: A method for determining the storage capacity and inflation / deflation rate of a compressed air energy storage gas reservoir based on thermodynamic response difference decomposition includes: A differential thermodynamic response model for a gas storage facility is established, and based on the differential thermodynamic response model, the maximum pressure that the gas storage facility can store and the maximum pressure that the air inside the gas storage facility can reach are obtained. On the two-dimensional plane of storage capacity and inflation / deflation rate, contour lines of maximum pressure and maximum pressure are drawn respectively. Using the intersection of the two contour lines, feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy pressure and storage constraints are determined, thus completing the optimized design of the compressed air energy storage tank.

[0006] Preferred methods for establishing differential models of the thermodynamic response of gas storage facilities include: Based on the mass conservation equation, energy conservation equation and gas state equation, a set of control equations is established to describe the changes in air temperature, pressure, mass and surrounding rock temperature during the gas filling and releasing cycle of the gas storage tank. The time and space are discretized, and the control equations are solved using the finite difference method to obtain the dynamic response of the air pressure, temperature, and surrounding rock temperature field in the gas storage tank as a function of time under the input conditions of preset storage capacity and gas filling and releasing rate. This completes the construction of the thermodynamic response finite difference model of the gas storage tank.

[0007] Preferred methods for constructing the mass conservation equation, energy conservation equation, and gas law include: Based on the mass flow rate of air released and the mass flow rate of air injected into the gas storage facility, a mass conservation equation is constructed. Based on the cave wall area, the average heat transfer coefficient between the cave wall and the air, the air temperature inside the gas storage tank, and the gas storage tank wall temperature, a cave wall heat flow equation is constructed. The specific enthalpy of air is obtained based on the specific internal energy, the air pressure inside the gas storage, the volume of the gas storage, and the air mass inside the gas storage. An energy conservation equation is constructed based on the mass of air in the gas storage facility, the filling and releasing rate, the specific internal energy of the air, the heat flow equation of the cave wall, and the specific enthalpy of the air. Based on the air pressure, volume, specific gas constant, and temperature inside the gas storage facility, a gas state equation is constructed.

[0008] Preferably, the method for constructing the governing equations includes: Based on the mass conservation equation, the air specific enthalpy, and the cave wall heat flow equation, the differential forms of the energy conservation equation and the gas state equation are obtained. Based on the differential forms of the energy conservation equation and the gas state equation, the relationship between temperature and pressure changes in the gas storage tank is obtained. Based on rock mass density, rock mass specific heat capacity, rock mass thermal conductivity, gas storage tank wall radius, gas storage tank wall average heat transfer coefficient, gas storage tank air temperature, gas storage tank wall temperature, gas storage tank wall temperature and ambient temperature, a relationship between temperature change caused by heat conduction in the rock mass is constructed. Based on the relationship between temperature and pressure changes within the gas storage facility and the relationship between temperature changes caused by heat conduction in the rock mass, the governing equations were constructed.

[0009] Preferred methods for obtaining maximum force and maximum pressure include: Based on the specific gas storage site, relevant thermodynamic parameters were obtained; Based on the relevant thermodynamic parameters, a design parameter space is constructed; Based on the differential thermodynamic response model of the gas storage facility, a complete gas filling and releasing cycle is simulated by traversing different combinations of storage capacity and filling / releasing rates in the design parameter space to obtain the maximum pressure and maximum pressure.

[0010] Preferably, the relevant thermodynamic parameters include cave radius, rock density, rock thermal conductivity, rock specific heat, heat transfer coefficient, air gas constant, air specific heat ratio, initial air and rock temperature, cave initial pressure, maximum internal pressure design value, and maximum pressure design value.

[0011] This invention also provides a system for determining the storage capacity and filling / discharging rate of a compressed air energy storage tank based on thermodynamic response difference decomposition, used to implement the method, comprising: The differential model construction module is used to establish a differential model of the thermodynamic response of the gas storage tank, and based on the differential model of the thermodynamic response of the gas storage tank, to obtain the maximum pressure that the gas storage tank can store and the maximum pressure that the air inside the gas storage tank can reach. The feasible design value acquisition module is used to draw contour lines of maximum energy and maximum pressure on a two-dimensional plane of storage capacity and inflation / deflation rate. By using the intersection of the two contour lines, the feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy energy storage and pressure constraints are determined, thus completing the optimized design of the compressed air energy storage tank.

[0012] Preferably, the difference model construction module includes: The governing equations construction unit is used to establish a set of governing equations that describe the changes in air temperature, pressure, mass, and surrounding rock temperature during the gas filling and releasing cycle of a gas storage tank, based on the mass conservation equation, energy conservation equation, and gas state equation. The differential model construction unit is used to discretize time and space, solve the control equations using the differential method, and obtain the dynamic response of air pressure, temperature, and temperature field and surrounding rock temperature field in the gas storage tank as a function of time under the input conditions of preset storage capacity and gas filling and releasing rate, thus completing the construction of the differential model of the thermodynamic response of the gas storage tank.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: More realistic physical processes: The thermodynamic response difference model adopted in this invention can fully consider the non-adiabatic heat exchange between the gas storage tank and the surrounding rock, and can better reflect the actual operating conditions and has higher estimation accuracy than the traditional adiabatic or isothermal assumption model.

[0014] Visualization and systematization of the design process: By plotting isopleths of pressure and pressure on the "capacity-inflation / expansion rate" plane, complex multi-parameter coupled design problems are transformed into intuitive graphical solutions. Designers can clearly see the performance corresponding to different combinations of design parameters and directly read the optimal or feasible solutions that simultaneously satisfy multiple design constraints.

[0015] High versatility: Based on fundamental principle equations, this method can adapt to different geological conditions, lining types and operating strategies by adjusting model parameters (surrounding rock characteristics, heat exchange coefficient, initial conditions, operating regime, etc.), providing a universal tool for the design of various CAES gas storage facilities.

[0016] Facilitates scheme comparison and optimization: Contour maps can be generated quickly, making it easy to compare multiple schemes and conduct sensitivity analysis in the early stages of design. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a general flowchart of the method according to an embodiment of the present invention; Figure 2 A schematic diagram of the spatiotemporal discretization of the gas storage facility and surrounding rock; Figure 3 Figure (a) shows an example of the dynamic response of gas storage tank pressure and pressure under different storage capacities and filling / discharging rates; where Figure (a) is... Time in 8 hours Schematic diagrams of pressure values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure (b) shows... Time in 8 hours Schematic diagrams of the γ values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure (c) shows... Time in 8 hours Schematic diagrams of pressure values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure (d) shows... Time in 8 hours Schematic diagrams of the sludge values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure 4 Figure 1 is a schematic diagram illustrating the plotting of contour lines for vortex and maximum pressure in the design parameter space and determining the design points. Figure (a) shows the contour lines for the parameter combinations of cave volume and air mass flow rate required to satisfy different constant maximum vortex values; Figure (b) shows the contour lines for the parameter combinations of cave volume and air mass flow rate required to satisfy different constant maximum pressures. Figure (c) illustrates the process of determining specific volume and flow rate design points through the intersection of contour lines for the Huntorf design constraint; Figure (d) shows that this method can be applied to different design constraints to obtain another set of feasible volume and flow rate parameters. Figure 5 A schematic diagram for determining the normalized pressure surface and design points in three-dimensional parameter space. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1: like Figure 1 As shown, a method for determining the storage capacity and filling / discharging rate of a compressed air energy storage gas tank based on thermodynamic response difference decomposition includes: S1: Establish a differential thermodynamic response model for the gas storage facility, and based on the differential thermodynamic response model, obtain the maximum pressure that the gas storage facility can store and the maximum pressure that the air inside the gas storage facility can reach.

[0022] 㶲 represents the maximum useful work that a system or energy flow can do to the outside world through a reversible process. For compressed gas energy storage power plants, 㶲 in the gas storage can be used to generate electricity.

[0023] A further implementation method is as follows: S11: The method for establishing a differential thermodynamic response model of a gas storage facility includes: S111: Based on the mass conservation equation, energy conservation equation, and gas state equation, establish a description of air temperature during the gas filling and discharging cycle of a gas storage tank. ,pressure ,quality and surrounding rock temperature The changing set of governing equations; A further implementation method involves constructing the mass conservation equation, energy conservation equation, and gas state equation by: constructing the mass conservation equation based on the mass flow rate of air released from the gas storage tank and the mass flow rate of air injected into the tank; and constructing the energy conservation equation based on the mass of air in the gas storage tank, the gas injection / release rate, the specific internal energy of the air, the heat flow equation of the tunnel wall, and the specific enthalpy of the air. Specifically, during the air filling and degassing stages, the mass conservation and energy conservation within the gas storage tank are expressed by equations (1) and (2), respectively: mass conservation equation: (1) Energy conservation equation: (2) In the formula, This refers to the rate of inflation and deflation. The specific internal energy of air, Release mass flow rate into the air. For the air inflation rate, The heat exchange rate of the gas storage tank wall. For air specific enthalpy, For time.

[0024] Based on the cave wall area, the average heat transfer coefficient between the cave wall and the air, the air temperature inside the gas storage tank, and the gas storage tank wall temperature, a cave wall heat flow equation is constructed; the heat exchange rate satisfies equation (3), and the cave wall heat flow equation is: (3) In the formula, The area of ​​the cave wall. The average heat transfer coefficient between the cave wall and the air. The air temperature inside the gas storage facility. This refers to the temperature of the gas storage tank wall.

[0025] Construct the relationship between specific enthalpy and specific internal energy, air pressure inside the gas storage tank, gas storage tank volume, and air mass inside the gas storage tank; the relationship between specific enthalpy and specific internal energy, pressure, volume, and mass is as follows: (4) In the formula, The air pressure inside the gas storage facility. This refers to the volume of the gas storage tank.

[0026] Based on the air pressure, volume, specific gas constant, and temperature inside the gas storage facility, a gas state equation is constructed. Gas state equation: (5) In the formula, air is the gas constant. =287 J / (kg·K).

[0027] A further implementation method involves constructing a system of governing equations, including: Based on the mass conservation equation, air specific enthalpy, and cave wall heat flow equation, the differential forms of the energy conservation equation and the gas state equation are obtained; combining equations (1), (4), and (3), the differential forms of equations (2) and (4) can be derived as follows: (6) In the formula, The specific enthalpy of the incoming air.

[0028] Based on the differential forms of the energy conservation equation and the gas state equation, the relationship between temperature and pressure changes within the gas storage tank is obtained; specifically, for an isochoric air storage system, the storage tank volume remains constant. =0. Based on equation (6), if we assume that the heat capacity of air is constant, the relationship between the temperature and pressure changes in the gas storage tank can be expressed as: (7) In the formula The heat capacity ratio of air ( =1.4), The temperature of the injected air.

[0029] Based on the rock mass density, specific heat capacity, thermal conductivity, gas storage tank wall radius, average heat transfer coefficient of the gas storage tank wall, air temperature inside the gas storage tank, rock mass temperature at the gas storage tank wall, and ambient temperature, a relationship between temperature changes caused by heat conduction in the rock mass is constructed; specifically, the temperature change caused by heat conduction in the rock mass is represented by equation (8): (8) In the formula, For the density of the rock mass, The specific heat capacity of the rock mass. The thermal conductivity of the rock mass Radial coordinates, The radius of the gas storage wall is denoted as . The average heat transfer coefficient between the cave wall and the air. The air temperature inside the gas storage facility. The temperature of the rock mass at the wall of the gas storage facility. The ambient temperature.

[0030] Based on the relationship between temperature and pressure changes within the gas storage facility and the relationship between temperature changes caused by heat conduction in the rock mass, the governing equations were constructed.

[0031] S112: Discretize the time and space, and solve the governing equations using the finite difference method to obtain the results under a specific storage capacity. and inflation / deflation rate Under input conditions, the air pressure inside the gas storage tank ,temperature , , ( ... Over time The dynamic response of the gas storage facility is changed, and a differential model of its thermodynamic response is constructed.

[0032] As the temperature and pressure inside the cave change, the amount of gas stored in the cave can be given by equation (9): (9) In the formula, The specific heat capacity of air. The ambient pressure is taken as 0.103 MPa.

[0033] The thermodynamic response of the gas storage tank can be determined by equations (7) to (8). However, when considering the thermal convection between the gas storage tank and the surrounding rock, it is difficult to give an analytical solution. To solve this problem, numerical solutions are derived by discretizing time and space, as shown in equations (10) and (11). A schematic diagram of this discretization scheme is shown below. Figure 2 As shown.

[0034] (10) (11) In the formula, For discrete time, For time step, For the time span, Divide time into quantities; For discrete spatial coordinates, For spatial step size, Where N is the spatial span (radius of the surrounding rock calculation area), and N is the number of spatial divisions. The radius of the gas storage wall is denoted as . For time indexing, For spatial indexing, see Figure 2 .

[0035] At this time, the discrete pressure inside the gas storage tank is The discrete temperatures within the gas storage facility are The air quality inside the gas storage facility is The discrete temperature in the surrounding rock is .

[0036] The initial conditions are: (12) In the formula, The initial pressure inside the gas storage facility. Initial temperature , The initial air mass inside the gas storage facility is calculated using the following formula: (13) Based on equations (7) to (8), the increments in temperature and pressure inside the gas storage tank and the increments in temperature within the surrounding rock can be expressed as: (14) The incremental values ​​obtained using equation (14) can be used to continuously update the temperature, pressure, and air quality within the gas storage facility. The specific expression is as follows: (15) Equations (14) and (15) provide a framework for determining the thermodynamic response of the gas storage tank and the surrounding rock.

[0037] The specific calculation process is as follows: a: Obtain the initial state variables (Equation 12); b: Calculate the increment using equation (14) Calculation order: First calculate the air increment. and Then calculate the temperature increment of the surrounding rock. Note the wall nodes. and internal nodes and outer boundary nodes The difference scheme (usually set to constant temperature) is different.

[0038] c: Perform state update using equation (15).

[0039] Furthermore, it should be noted that the convergence of equation (14) must satisfy the following condition: (16) In the formula, The thermal diffusivity of the rock mass is defined as follows: is the thermal conductivity of the rock mass.

[0040] A further implementation method for obtaining the maximum pressure and maximum pressure includes: Based on the specific gas storage site, relevant thermodynamic parameters are obtained; a further implementation method involves that the relevant thermodynamic parameters include the radius of the cavity. Rock mass density thermal conductivity of rock mass Specific heat of rock mass heat transfer coefficient air gas constant air specific heat capacity ratio Initial air and rock mass temperature Initial pressure of the cave Maximum internal pressure design value Maximum design value wait.

[0041] Based on relevant thermodynamic parameters, a design parameter space is constructed. Using a differential thermodynamic response model of the gas storage facility, a complete filling and releasing cycle is simulated by traversing different combinations of storage capacity and filling / releasing rates within the design parameter space to obtain the maximum pressure and maximum pressure. Specifically, the design parameter space is defined, which consists of the gas storage capacity... and inflation / deflation rate It consists of two dimensions. Based on the difference model established in step one, it iterates through a series of discrete values ​​within the design parameter space. Combination points. For each combination point, run a differential model to simulate a complete charge-discharge cycle. Extract two key design parameters from the simulation results: (a) the maximum gas volume that the storage tank can store during this cycle. (b) The maximum pressure reached by the air in the gas storage tank during this cycle. Therefore, for each point in the design parameter space... Assign a pair of corresponding performance metrics ( ).

[0042] S2: On the two-dimensional plane of storage capacity and inflation / deflation rate, draw contour lines for maximum pressure and maximum pressure respectively. Using the intersection of the two contour lines, determine the feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy pressure and storage constraints, thus completing the optimized design of the compressed air energy storage tank. Figure 5 As shown.

[0043] Specifically, contour maps are drawn, and the reservoir capacity and air inflation / deflation rates are determined. (The text then abruptly shifts to a seemingly unrelated topic: "Based on the reservoir capacity...") and inflation / deflation rate On the two-dimensional design parameter planar diagram, draw: (a) maximum yoke Contour lines: connecting all contour lines that make Equal to a specific value (e.g., design target) )of The curve formed by the points. (b) Maximum pressure Contour lines: connecting all contour lines that make It equals a specific value (e.g., the maximum internal pressure design value). )of The curve formed by the points. The intersection of these two contour lines on the design parameter plane, that is, the point that simultaneously satisfies "maximum design value". "and "maximum internal pressure design value" "The feasible design point under the two constraints. The x-coordinate of the intersection point is the required gas storage capacity." The vertical axis represents the required air inflation / deflation rate. .

[0044] Example 2: This embodiment provides an estimate of the volume and inflation / deflation rate of the famous German demonstration power plant, Huntorf.

[0045] Step 1: Establish and solve the differential thermodynamic response model of the gas storage tank The finite difference method is employed. The air inside the gas storage facility is considered as a lumped parameter (single node), and its state is determined by pressure. ,temperature and quality describe.

[0046] The surrounding rock mass is radially ( (Direction) Discretized into Layered concentric rings (e.g.: Each layer has a uniform temperature ,in( ( ) is the wall layer that is in contact with air.

[0047] The governing equations (mass conservation, energy conservation, gas state equation, and rock mass heat conduction equation) are discretized in time and space. Time step... The numerical stability condition (Equation (16)) must be met.

[0048] Step 2: For a specific gas storage site, provide the relevant thermodynamic parameters: Cave radius =20 m; rock mass density =2,100 kg / m 3 thermal conductivity of rock mass =4 W / ( ·K); Specific heat capacity of rock mass =840J / ( ·K); heat transfer coefficient =30 W / (m 2 ·K); air gas constant =287 J / ( ·K); specific heat ratio of air =1.4; Initial air and rock mass temperature =40℃; initial pressure of the cave =5.9 MPa; Maximum design value =580 MWh; operating pressure range of 4.6 to 6.6 MPa; rated output power of 290 MW; charging time and discharging time of 8 hours and 2 hours, respectively.

[0049] Meanwhile, the actual total cavern volume is known to be 300,000 cubic meters (m³), and the average inflation / deflation rate is 108 kg / s (kg / s), which will be used as a reference for the differential numerical results. Step 3: Traverse the parameter space for calculation. Set the library capacity. The investigation range is [200,000,500,000] m³, and the inflation / deflation mass flow rate is... The observation range is [50, 200] kg / s. The step size is [e.g., ...]. Step length 20,000 m³ (Step length 10kg / s) Traverse all Combination. For each combination, run the difference model from step one to simulate an "8-hour inflation + 2-hour deflation" cycle, and record the maximum pressure calculated during this cycle. and maximum pressure like Figure 3 As shown. Figure 3 (a) is Time in 8 hours A schematic diagram of the pressure values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure 3 (b) is Time in 8 hours Schematic diagrams of the sludge values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure 3 (c) is Time in 8 hours A schematic diagram of the pressure values ​​obtained at 80, 90, 100, 110, and 120 (kg / s); Figure 3 (d) is Time in 8 hours Schematic diagrams of the sludge values ​​obtained at 80, 90, 100, 110, and 120 (kg / s).

[0050] Step 4: Draw contour lines and determine design points. All the data obtained in Step 4... Data, in Drawing on a plane =580MWh contour lines and The contour line is 6.6 MPa. For example... Figure 4 As shown, Figure 4 (a) Contours of the cave volume and air mass flow rate required to satisfy different constant maximum values ​​were plotted. Figure 4 (b) Contours of the parameters required to satisfy different constant maximum pressures, namely cave volume and air mass flow rate, were plotted. Figure 4 (c) Demonstrates the process of determining the specific volume and flow design points based on the intersection of contour lines for the Huntorf design constraint. Two contour lines intersect at point A. The coordinates of intersection point A are read: ≈348400m³ ≈104.5kg / s. Figure 4 (d) demonstrates that this method can be applied to different design constraints to obtain another set of feasible volume and flow parameters.

[0051] Results Analysis and Comparison: Storage capacity ( Calculated value 348,400 m³ > Actual value = 300,000 m³. The relative error is 16.133%. Inflation and deflation rates ( The calculated value of 104.5 kg / s and the actual value of 108 kg / s have a relative error of 3.24%. The analysis revealed an overestimation of the storage capacity, while the inflation / deflation rates were relatively accurate. This is primarily because the model calculated the volume of pure compressed air to account for the overestimation. In reality, the Huntorf power plant injects and burns fuel during deflation (secondary combustion), significantly increasing the output energy. Therefore, to achieve the same output power (290MW), the pure compressed air approach requires storing more volume (i.e., a larger volume). Consequently, in practical design, the storage capacity proposed by this method can be appropriately reduced according to specific design requirements. For example, considering a storage capacity reduction factor of 0.9 for the Huntorf power plant, a more accurate storage capacity estimate can be obtained.

[0052] The analysis indicates that the gas filling and venting rates are relatively accurate, and that they mainly depend on power requirements and operating conditions. No correction is needed, which also demonstrates the correctness of using a thermodynamic differential model of the gas storage facility that considers heat exchange with the surrounding rock to calculate the storage capacity and filling / venting rates.

[0053] Example 3: This invention also provides a system for determining the storage capacity and inflation / deflation rate of a compressed air energy storage gas tank based on thermodynamic response difference decomposition, used to implement the method of Embodiment 1, comprising: The differential model building module is used to establish a differential model of the thermodynamic response of the gas storage tank, and based on the differential model of the thermodynamic response of the gas storage tank, to obtain the maximum pressure that the gas storage tank can store and the maximum pressure that the air inside the gas storage tank can reach. The feasible design value acquisition module is used to draw contour lines of maximum energy and maximum pressure on a two-dimensional plane of storage capacity and inflation / deflation rate. By using the intersection of the two contour lines, the feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy energy storage and pressure constraints are determined, thus completing the optimized design of the compressed air energy storage tank.

[0054] A further implementation method is that the difference model construction module includes: The control equations construction unit is used to establish a set of control equations describing the changes in air temperature, pressure, mass, and surrounding rock temperature during the gas filling and releasing cycle of a gas storage tank, based on the mass conservation equation, energy conservation equation, and gas state equation. The differential model building unit is used to discretize time and space, solve the control equations using the differential method, and obtain the dynamic response of air pressure, temperature, and temperature field and surrounding rock temperature field in the gas storage tank as a function of time under the input conditions of preset storage capacity and gas filling and releasing rate, thus completing the construction of the differential model of the thermodynamic response of the gas storage tank.

[0055] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for determining the storage capacity and filling / discharging rate of a compressed air energy storage tank based on thermodynamic response difference decomposition, characterized in that, include: A differential thermodynamic response model for a gas storage facility is established, and based on the differential thermodynamic response model, the maximum pressure that the gas storage facility can store and the maximum pressure that the air inside the gas storage facility can reach are obtained. On the two-dimensional plane of storage capacity and inflation / deflation rate, contour lines of maximum pressure and maximum pressure are drawn respectively. Using the intersection of the two contour lines, feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy pressure and storage constraints are determined, thus completing the optimized design of the compressed air energy storage tank.

2. The method according to claim 1, characterized in that, Methods for establishing differential models of the thermodynamic response of gas storage facilities include: Based on the mass conservation equation, energy conservation equation and gas state equation, a set of control equations is established to describe the changes in air temperature, pressure, mass and surrounding rock temperature during the gas filling and releasing cycle of the gas storage tank. The time and space are discretized, and the control equations are solved using the finite difference method to obtain the dynamic response of the air pressure, temperature, and surrounding rock temperature field in the gas storage tank as a function of time under the input conditions of preset storage capacity and gas filling and releasing rate. This completes the construction of the thermodynamic response finite difference model of the gas storage tank.

3. The method according to claim 2, characterized in that, The methods for constructing the mass conservation equation, energy conservation equation, and gas law include: Based on the mass flow rate of air released and the mass flow rate of air injected into the gas storage facility, a mass conservation equation is constructed. Based on the cave wall area, the average heat transfer coefficient between the cave wall and the air, the air temperature inside the gas storage tank, and the gas storage tank wall temperature, a cave wall heat flow equation is constructed. The specific enthalpy of air is obtained based on the specific internal energy, the air pressure inside the gas storage, the volume of the gas storage, and the air mass inside the gas storage. An energy conservation equation is constructed based on the mass of air in the gas storage facility, the filling and releasing rate, the specific internal energy of the air, the heat flow equation of the cave wall, and the specific enthalpy of the air. Based on the air pressure, volume, specific gas constant, and temperature inside the gas storage facility, a gas state equation is constructed.

4. The method according to claim 3, characterized in that, Methods for constructing a system of governing equations include: Based on the mass conservation equation, the air specific enthalpy, and the cave wall heat flow equation, the differential forms of the energy conservation equation and the gas state equation are obtained. Based on the differential forms of the energy conservation equation and the gas state equation, the relationship between temperature and pressure changes in the gas storage tank is obtained. Based on rock mass density, rock mass specific heat capacity, rock mass thermal conductivity, gas storage tank wall radius, gas storage tank wall average heat transfer coefficient, gas storage tank air temperature, gas storage tank wall temperature, gas storage tank wall temperature and ambient temperature, a relationship between temperature change caused by heat conduction in the rock mass is constructed. Based on the relationship between temperature and pressure changes within the gas storage facility and the relationship between temperature changes caused by heat conduction in the rock mass, the governing equations were constructed.

5. The method according to claim 2, characterized in that, Methods to obtain maximum pressure and maximum force include: Based on the specific gas storage site, relevant thermodynamic parameters were obtained; Based on the relevant thermodynamic parameters, a design parameter space is constructed; Based on the differential thermodynamic response model of the gas storage facility, a complete gas filling and releasing cycle is simulated by traversing different combinations of storage capacity and filling / releasing rates in the design parameter space to obtain the maximum pressure and maximum pressure.

6. The method according to claim 5, characterized in that, The relevant thermodynamic parameters include cave radius, rock density, rock thermal conductivity, rock specific heat, heat transfer coefficient, air gas constant, air specific heat ratio, initial air and rock temperatures, initial cave pressure, maximum internal pressure design value, and maximum design value.

7. A system for determining the storage capacity and inflation / deflation rate of a compressed air energy storage tank based on thermodynamic response difference decomposition, used to implement the method described in any one of claims 1-6, characterized in that, include: The differential model construction module is used to establish a differential model of the thermodynamic response of the gas storage tank, and based on the differential model of the thermodynamic response of the gas storage tank, to obtain the maximum pressure that the gas storage tank can store and the maximum pressure that the air inside the gas storage tank can reach. The feasible design value acquisition module is used to draw contour lines of maximum energy and maximum pressure on a two-dimensional plane of storage capacity and inflation / deflation rate. By using the intersection of the two contour lines, the feasible design values ​​of storage capacity and inflation / deflation rate that simultaneously satisfy energy storage and pressure constraints are determined, thus completing the optimized design of the compressed air energy storage tank.

8. The system according to claim 7, characterized in that, The difference model construction module includes: The governing equations construction unit is used to establish a set of governing equations that describe the changes in air temperature, pressure, mass, and surrounding rock temperature during the gas filling and releasing cycle of a gas storage tank, based on the mass conservation equation, energy conservation equation, and gas state equation. The differential model construction unit is used to discretize time and space, solve the control equations using the differential method, and obtain the dynamic response of air pressure, temperature, and temperature field and surrounding rock temperature field in the gas storage tank as a function of time under the input conditions of preset storage capacity and gas filling and releasing rate, thus completing the construction of the differential model of the thermodynamic response of the gas storage tank.

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