Method for determining stable cycle working condition of gas storage device, and electronic device

Abstract

The application provides a kind of gas storage device stable cycle condition determination method and electronic equipment, applied in compressed air energy storage power station gas storage device;Steps are as follows: S1: collect the preliminary design parameters and initial operating parameters of compressed air energy storage power station;S2: according to the type of gas storage device, establish the non-steady-state heat conduction model of the internal and external environment of gas storage device;S3: construct the non-steady-state flow energy equation of gas storage device coupled with the non-steady-state heat conduction model of external environment, establish the gas storage device operating condition parameter solving model, and determine the boundary condition;S4: the gas storage device operating condition parameter solving model established in step S3 is solved by using the discretization method, to obtain the first cycle from the initial running time calculation, then iteratively calculate the transient operating condition parameter variation characteristics of subsequent time steps one by one, and further determine the stable cycle condition by using time series analysis.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a method for determining the stable cyclic operating conditions of a compressed air energy storage system's storage device, as well as an electronic device thereof. Background Technology

[0002] In the preliminary design phase of a compressed air energy storage power station, determining the stable cycle operating conditions of the gas storage device is a prerequisite for achieving efficient and reliable energy conversion and storage. The working principle of a compressed air energy storage power station is to convert electrical energy into the thermodynamic energy of high-pressure air and a heat storage medium during the energy storage phase, and to release energy through air expansion during the energy release phase. Therefore, the operating conditions of the gas storage device during the stable cycle of a compressed air energy storage power station are crucial for determining the power station system scheme and controlling the energy storage-release cycle. However, due to the influence of various factors such as ambient temperature changes, system design parameters, heat loss, and operating conditions, the rated operating conditions of the gas storage device in the system scheme proposed in the preliminary design phase often fail to reflect the actual stable cycle operating conditions of the system, which is detrimental to the overall performance improvement and long-term stable operation of the compressed air energy storage power station. Furthermore, determining the stable cycle operating conditions is also important for the design, construction, and operation and maintenance of the gas storage device, especially since the temperature range under the stable cycle operating conditions relates to the performance requirements of the gas storage device's wall materials. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method and electronic equipment for determining the stable cyclic operating conditions of the gas storage device in a compressed air energy storage system, which is used to determine the stable operating conditions of the gas storage device in a compressed air energy storage power station from the initial state to the final stable cyclic operation, and serves as a reference for the design, construction and operation and maintenance of a compressed air energy storage power station.

[0004] To achieve the above and other related objectives, this invention provides a method for determining the stable cyclic operating conditions of a gas storage device, applicable to the gas storage device of a compressed air energy storage power station; the steps are as follows:

[0005] S1: Collect preliminary design parameters and initial operating parameters of the compressed air energy storage power station;

[0006] S2: Based on the type of gas storage device, establish an unsteady heat conduction model between the inside of the gas storage device and the external environment;

[0007] S3: Construct the unsteady flow energy equation of the gas storage device coupled with the unsteady heat conduction model of the external environment, establish the solution model of the operating condition parameters of the gas storage device, and determine the boundary conditions;

[0008] S4: The discretization method is used to solve the gas storage device operating condition parameter solution model established in step S3. The first cycle is calculated from the initial operating time. Then, the transient operating condition parameter change characteristics of each subsequent time step are iteratively calculated. Finally, time series analysis is used to determine the stable cycle operating condition.

[0009] Preferably, the preliminary design parameters in step S1 include inlet parameters, settling time, exhaust parameters, gas storage pressure limit, gas storage device volume, inner wall surface area, wall material parameters, and environmental parameters; the initial operating parameters include the initial gas pressure and temperature in the gas storage device; wherein the inlet parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; and the environmental parameters include ambient temperature, thermal conductivity, or convective heat transfer coefficient.

[0010] Preferably, the types of gas storage devices in step S2 include underground gas storage devices and above-ground gas storage devices. The underground gas storage devices include salt caverns and underground chambers, while the above-ground gas storage devices include pipeline steel and high-pressure gas tanks. The wall materials in the preliminary parameters of step S1 are determined according to the type of gas storage device and the preliminary actual plan. The wall material of the salt cavern is the rock inside the cave, and the wall material of the underground chamber is a steel lining and backfill concrete. The wall materials of the above-ground gas storage device are steel, composite materials, and anti-corrosion coatings.

[0011] Preferably, the environmental parameters in the preliminary parameters of step S1 are related to the type of gas storage device; the environmental parameters of the underground gas storage device are the annual average temperature of the surrounding rock at the designed underground gas storage device and the thermal conductivity of the surrounding rock obtained through geological survey; the environmental parameters of the above-ground gas storage device are the local hourly historical average temperature, hourly surface solar radiation intensity, solar radiation absorptivity of the above-ground gas storage device and air convection heat transfer coefficient.

[0012] Preferably, in step S2, the unsteady heat conduction model between the gas storage device and the external environment is meshed using a discretization method; the air inside the gas storage device only considers convective heat transfer near the wall; the wall material of the gas storage device is meshed according to the material of each layer: the outer side of the wall of the underground gas storage device is meshed using a rock layer of a specific length in the normal direction, with the characteristic length being 0.2-0.3 times the radius of the sphere corresponding to the equivalent volume of the underground gas storage device; the outer layer of the wall of the above-ground gas storage device adopts the average surface heat transfer coefficient of the fluid sweeping across the horizontal pipe or sphere.

[0013] Preferably, in step S2, the unsteady-state heat conduction models between different types of gas storage devices and the external environment are as follows: The formula for the unsteady-state heat conduction model between the inside of the salt cavern gas storage device and the external environment is as follows:

[0014]

[0015]

[0016] Among them, T i,j T is the temperature of rock mesh i at the j-th time step; i,j+1 T is the temperature of rock mesh i at time step j+1. i-1,j T is the temperature of rock stratum grid i-1 at the j-th time step. i+1,j The temperature of the rock layer grid i+1 at the j-th time step is d, where d is the width of the rock layer grid, Δτ is the time step, and r is the temperature of the rock layer grid i+1 at the j-th time step. i-1 It is the equivalent thermal resistance between rock layer grid i and rock layer grid i-1, r i+1 is the equivalent thermal resistance between rock layer grid i and rock layer grid i+1, and h is the forced convection heat transfer coefficient of air; when i=1, it indicates that this is the first rock layer in the salt cave that is in contact with air.

[0017] The unsteady-state heat transfer model between the interior and external environment of an artificially excavated underground gas storage device is based on the following formula:

[0018]

[0019]

[0020]

[0021] Among them, T i,j It is the temperature of the grid i of the wall material and the rock strata as a whole at the j-th time step; T i,j+1 T is the temperature of the grid i of the wall material and the rock strata at time step j+1. i-1,j The temperature of the grid i-1 of the wall material and the rock strata at the j-th time step is T. i+1,j d is the temperature of the overall grid of the wall material and rock strata at time step i+1, d is the grid width of the overall wall material and rock strata, Δτ is the time step, and r is the temperature of the overall grid of the wall material and rock strata at time step j. i-1 The equivalent thermal resistance r between grid i of the wall material and the rock strata as a whole and grid i-1 of the wall material and the rock strata as a whole is... i+1 is the equivalent thermal resistance between grid i of the wall material and the overall rock stratum and grid i+1 of the wall material and the overall rock stratum; h is the forced convection heat transfer coefficient of air; n is the amount of wall material; m is the order of the wall material in a certain layer from the inside to the outside; l k Let be the thickness of the k-th type of wall material. When i = 1, it indicates that this is the first layer of wall material in contact with the air inside the underground cavern.

[0022] The unsteady-state heat conduction model between the pipeline steel and the internal environment of the high-pressure gas storage tank and the external environment is adopted using the following formula:

[0023]

[0024]

[0025]

[0026] Among them, T i,j T is the temperature of the wall material mesh i at the j-th time step; i,j+1 T is the temperature of the wall material mesh i at time step j+1. i-1,j T is the temperature of the wall material mesh i-1 at the j-th time step. i+1,j The temperature of the wall material mesh i+1 at time step j is given by d, where d is the mesh width of the wall material, Δτ is the time step, and r is the temperature of the wall material mesh i+1 at time step j. i-1 It is the equivalent thermal resistance between mesh i and mesh i-1 of the wall material, r i+1 is the equivalent thermal resistance between grid i and grid i+1 of the wall material, and h is the forced convection heat transfer coefficient of the air. s It refers to the average surface heat transfer coefficient of the outer side of the wall based on the fluid flowing over the horizontal tube or sphere; n is the amount of wall material, m is the order of the wall material in a certain layer from the inside to the outside, and l k Let be the thickness of the k-th type of wall material. When i = 1, this indicates that it is the first layer of wall material in contact with air inside the above-ground gas storage device. α is the solar radiation absorptivity of the outer wall of the above-ground gas storage device, W... s It is the local solar radiation power.

[0027] Preferably, the unsteady flow energy equation of the gas storage device coupled with the unsteady heat conduction model of the external environment in step S3 is as follows:

[0028]

[0029] m j+1 =m j +q m,j ·Δτ (10)

[0030] v j+1 =V / m j+1 (11)

[0031] Among them, u j+1 It is the specific thermodynamic energy of the air inside the gas storage device at time step j+1, m j It is the air quality inside the gas storage device at time step j, u j q is the specific thermodynamic energy of the air inside the gas storage device at time step j. m,j It is the gas mass flow rate, positive for filling and negative for releasing, h jT is the specific enthalpy of the gas being charged / de-charged at time step j, A is the surface area of ​​the inner wall of the gas storage device, and T is the specific enthalpy of the gas being charged / de-charged at time step j. a,j T is the internal air temperature of the gas storage device at time step j. i＝1,j denoted as λ1, where λ1 is the temperature of the first layer of surrounding rock mesh in contact with the wall of the gas storage device at time step j; h is the forced convection heat transfer coefficient of the air inside the gas storage device; d is the mesh step size; λ1 is the thermal conductivity of the wall material or rock layer in contact with the air; and Δτ is the time step.

[0032] Preferably, in step S4, from the j-th time step to the (j+1)-th time step, the temperature of the gas inside the gas storage device at the (j+1)-th time step is calculated according to formulas (9) to (11). Then, as a boundary condition, the influence of different external environments of the gas storage device on the temperature of the first layer of grid on the inner wall of the gas storage device at the (j+1)-th time step is analyzed according to formulas (1) to (8), and the temperature of the inner wall of the gas storage device at the (j+1)-th time step is calculated. The temperature of the inner wall of the gas storage device at the (j+1)-th time step is used as a boundary condition and input into formulas (9) to (11) to obtain the state parameters of the gas inside the gas storage device at the (j+2)-th time step.

[0033] Preferably, in step S4, the initial cycle calculation step for the compressed air energy storage power station's gas storage device is as follows:

[0034] S4.1: When the compressed air energy storage power station is first charged to the rated maximum pressure, the time to reach the rated maximum pressure is calculated based on S2 and S3, the energy storage duration of the first cycle is determined, and the transient operating parameters of each time step within the energy storage duration are recorded, including the gas state parameters inside the gas storage device, the temperature distribution of the wall material and the external environment.

[0035] S4.2: The transient operating parameters at the end of the first cycle energy storage stage are used as the initial and boundary conditions for calculating the gas state parameters inside the gas storage device during the resting stage. Then, the changes in the gas state parameters inside the gas storage device are calculated through S2 and S3. During the resting stage, the gas mass flow rate of the gas storage device is 0. The transient operating parameters at each time step of the resting time are recorded.

[0036] S4.3: The transient operating parameters at the end of the settling phase serve as the initial and boundary conditions for calculating the internal gas state parameters of the gas storage device during the energy release phase. During the calculation, the transient operating parameters of the gas storage device at each time step also synchronously affect the exhaust parameters of that transient phase. The end point of the energy release phase is the rated minimum pressure. When the gas pressure inside the gas storage device reaches the rated minimum pressure, the time to reach the rated minimum pressure is recorded to determine the energy release duration of the first cycle, and the transient operating parameters at each time step during the energy release phase are recorded.

[0037] S4.4: Calculate the transient operating parameters for each time step of the resting phase after the energy release phase ends, as in step (2), and use them as the initial and boundary conditions for the next cycle.

[0038] S4.5: Repeat steps S4.1 to S4.4 to calculate the transient operating parameters for multiple cycles. Record the operating parameters such as energy storage duration, energy release duration, highest temperature during the energy storage stage, lowest temperature during the energy storage stage, highest temperature during the energy release stage, and lowest temperature during the energy release stage in each cycle. Use time series analysis to determine the stable operating conditions of each operating parameter when they reach a steady state.

[0039] To achieve the above or other objectives, the present invention also discloses an electronic device that stores the method for determining the stable cyclic operating conditions of the gas storage device described above.

[0040] As described above, the present invention relates to a method for determining the stable cyclic operating condition of a compressed air energy storage system's gas storage device, and an electronic device thereof, which has the following beneficial effects:

[0041] 1. This invention takes the initial conditions and boundary parameters of the first cycle as input, establishes the unsteady flow energy equation of the gas storage device with unsteady heat conduction between the inside of the gas storage device and the external environment, and can determine the stable cycle operating condition of the compressed air energy storage power station more accurately through multiple iterative calculations.

[0042] 2. Compressed air energy storage power stations operate under varying conditions over long periods. Compared to rated conditions, a defined stable cyclic operating condition allows for more accurate calculation of the capacity of the compressed air energy storage power station and characterization of the energy storage-release features during normal operation.

[0043] 3. The parameter range of stable cycle operation of the energy storage power station can be preliminarily determined in the early preliminary design stage, providing theoretical and data support for power station design and material selection. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating a specific implementation method according to this application;

[0045] Figure 2 This is a circuit diagram of the underground gas storage device in the specific embodiment of this application, starting from the first cycle.

[0046] Figure 3 This is a diagram showing the highest and lowest stable circulation temperatures of the underground gas storage device in a specific embodiment of this application.

[0047] Figure 4 This is a stable cycle diagram of the above-ground gas storage device in the specific embodiment of this application, starting from the first cycle;

[0048] Figure 5This is a diagram showing the highest and lowest stable circulation temperatures of the above-ground gas storage device in a specific embodiment of this application. Detailed Implementation

[0049] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0050] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0051] like Figure 1 As shown, this invention provides a method for determining the stable cyclic operating condition of a gas storage device, applicable to the gas storage device of a compressed air energy storage power station; the steps are as follows:

[0052] S1: Collect preliminary design parameters and initial operating parameters of the compressed air energy storage power station;

[0053] S2: Based on the type of gas storage device, establish an unsteady heat conduction model between the inside of the gas storage device and the external environment;

[0054] S3: Construct the unsteady flow energy equation of the gas storage device coupled with the unsteady heat conduction model of the external environment, establish the solution model of the operating condition parameters of the gas storage device, and determine the boundary conditions;

[0055] S4: The discretization method is used to solve the gas storage device operating condition parameter solution model established in step S3. The first cycle is calculated from the initial operating time. Then, the transient operating condition parameter change characteristics of each subsequent time step are iteratively calculated. Finally, time series analysis is used to determine the stable cycle operating condition.

[0056] The method for determining the stable cycle operating conditions of a gas storage device involved in this invention first collects the preliminary design parameters and operating parameters of the compressed air energy storage power station, then constructs an unsteady-state heat conduction model between the gas storage device and the external environment, and then couples the unsteady-state heat conduction model into the energy flow equation of the gas storage device in the working cycle; based on the preliminary design parameters and operating parameters collected in the early stage, starting from the first cycle of the compressed air energy storage power station, the operating condition parameters of each subsequent cycle are iteratively calculated, and the operating condition parameters of the key nodes characterizing stable operation are determined by time series analysis.

[0057] Preferably, in this embodiment, the preliminary design parameters in step S1 include inlet parameters, settling time, exhaust parameters, gas storage pressure limit, gas storage device volume, inner wall surface area, wall material parameters, and environmental parameters; the initial operating parameters include the initial gas pressure and temperature in the gas storage device; wherein the inlet parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; and the environmental parameters include ambient temperature, thermal conductivity, or convective heat transfer coefficient.

[0058] Preferably, in this embodiment, the wall material in the preliminary parameters of step S1 is determined according to the type of gas storage device and the preliminary actual plan. The types of gas storage devices include underground gas storage devices and above-ground gas storage devices. The underground gas storage devices include salt caverns and underground chambers, and the above-ground gas storage devices include pipeline steel and high-pressure gas tanks. The wall material of the salt cavern is the rock inside the cave, and the wall material of the underground chamber is a steel lining and backfill concrete. The wall material of the above-ground gas storage device is steel, composite material and anti-corrosion coating.

[0059] Preferably, in this embodiment, the environmental parameters in the preliminary parameters of step S1 are the thermal properties of the environment in which the gas storage device is located. The environmental parameters are related to the type of gas storage device. For underground gas storage devices, the environment is a rock stratum at a certain depth underground, and the environmental parameters are the annual average temperature and thermal conductivity of the underground rock stratum at that depth, which are generally obtained through geological surveys. For above-ground gas storage devices, pipeline steel and high-pressure gas tanks are usually exposed to the air; therefore, their environmental parameters are the local hourly average ground temperature and the convective heat transfer coefficient of the air.

[0060] It should be explained that the above-ground gas storage device is deployed on the ground and is affected by solar radiation. The wall of the gas storage device will absorb some of the solar radiation energy. This part of the energy can be calculated by multiplying the absorptivity of the coating on the outer surface of the gas storage device with the local solar radiation power.

[0061] Preferably, in step S2, the unsteady-state heat conduction model between the inside of the gas storage device and the external environment is established using a discretization method for mesh generation. The heat exchange between the air inside the gas storage device and the external environment needs to consider three aspects: convective heat transfer from the air inside the gas storage device to the wall, thermal conductivity of the multilayer materials within the wall, and heat exchange between the wall and the external environment.

[0062] Furthermore, in establishing the unsteady heat conduction model between the internal and external environments of the gas storage device, a discretization method is used for mesh generation. When the compressed air energy storage power station is in operation, the valves of the gas storage device periodically open and close, and high-pressure air enters and exits at a high velocity and flow rate. The internal gas flow is relatively strong, and the air in different areas can be fully mixed in a short time. Therefore, it can be approximately assumed that the internal air convective heat transfer is sufficient and the temperature field is approximately uniform. Only the convective heat transfer near the wall needs to be considered, and there is no need to mesh the internal air.

[0063] Furthermore, in establishing the unsteady-state heat conduction model between the gas storage device and its external environment, a discretization method is used for mesh generation. Since the gas storage device is subjected to high pressure, the wall material has a certain thickness. A small length is taken along the thickness direction as the mesh step size to divide the heat transfer mesh within the wall material. The mesh step size is 0.1–0.2 cm, realizing the heat conduction calculation of the multi-layered material within the wall. Because the external environment of the underground gas storage device is rock strata, a specific length of rock strata needs to be taken along the normal direction of the gas storage device wall for mesh generation. This specific length is 0.2–0.3 times the radius of the sphere corresponding to the equivalent volume of the underground gas storage device.

[0064] Furthermore, in establishing the unsteady heat conduction model between the inside and outside environment of the gas storage device, a discretization method is used for mesh generation. When the gas storage device is an above-ground gas storage device (pipeline steel, high-pressure gas storage tank), the wall material of the gas storage device needs to be meshed. The average surface heat transfer coefficient of the fluid sweeping over the horizontal pipe or sphere is used on the outside of the wall.

[0065] Preferably, in step S2, the unsteady-state heat conduction models between different types of gas storage devices and the external environment are as follows:

[0066] First: When the gas storage device is a salt cavern, the unsteady heat conduction model formula between the inside of the salt cavern gas storage device and the external environment is as follows:

[0067]

[0068]

[0069] Among them, T i,j T is the temperature of rock mesh i at the j-th time step; i,j+1T is the temperature of rock mesh i at time step j+1. i-1,j T is the temperature of rock stratum grid i-1 at the j-th time step. i+1,j The temperature of the rock layer grid i+1 at the j-th time step is d, where d is the width of the rock layer grid, Δτ is the time step, and r is the temperature of the rock layer grid i+1 at the j-th time step. i-1 It is the equivalent thermal resistance between rock layer grid i and rock layer grid i-1, r i+1 is the equivalent thermal resistance between rock layer grid i and rock layer grid i+1, and h is the forced convection heat transfer coefficient of air; when i=1, it indicates that this is the first rock layer in the salt cave that is in contact with air.

[0070] Second: When the gas storage device is an underground chamber, the unsteady-state heat conduction model between the interior of the artificially excavated underground chamber gas storage device and the external environment adopts the following formula:

[0071]

[0072]

[0073]

[0074] Among them, T i,j T is the temperature of the grid i of the wall material and the rock strata as a whole at the j-th time step; i,j+1 T is the temperature of the grid i of the wall material and the rock strata at time step j+1. i-1,j The temperature of the grid i-1 of the wall material and the rock strata at the j-th time step is T. i+1,j d is the temperature of the overall grid of the wall material and rock strata at time step i+1, d is the grid width of the overall wall material and rock strata, Δτ is the time step, and r is the temperature of the overall grid of the wall material and rock strata at time step j. i-1 The equivalent thermal resistance r between grid i of the wall material and the rock strata as a whole and grid i-1 of the wall material and the rock strata as a whole is... i+1 is the equivalent thermal resistance between grid i of the wall material and the overall rock stratum and grid i+1 of the wall material and the overall rock stratum; h is the forced convection heat transfer coefficient of air; n is the amount of wall material; m is the order of the wall material in a certain layer from the inside to the outside; l k Let be the thickness of the k-th type of wall material. When i = 1, it indicates that this is the first layer of wall material in contact with the air inside the underground cavern.

[0075] Third: When the gas storage device is an above-ground gas storage device, the unsteady-state heat conduction model between the pipeline steel and the inside of the high-pressure gas storage tank and the external environment is adopted using the following formula:

[0076]

[0077]

[0078]

[0079] Among them, T i,j T is the temperature of the wall material mesh i at the j-th time step; i,j+1 T is the temperature of the wall material mesh i at time step j+1. i-1,j T is the temperature of the wall material mesh i-1 at the j-th time step. i+1,j The temperature of the wall material mesh i+1 at time step j is given by d, where d is the mesh width of the wall material, Δτ is the time step, and r is the temperature of the wall material mesh i+1 at time step j. i-1 It is the equivalent thermal resistance between mesh i and mesh i-1 of the wall material, r i+1 is the equivalent thermal resistance between grid i and grid i+1 of the wall material, and h is the forced convection heat transfer coefficient of the air. s It refers to the average surface heat transfer coefficient of the outer side of the wall based on the fluid flowing over the horizontal tube or sphere; n is the amount of wall material, m is the order of the wall material in a certain layer from the inside to the outside, and l k Let be the thickness of the k-th type of wall material. When i = 1, it indicates that this is the first layer of wall material in contact with air inside the above-ground gas storage device; α is the solar radiation absorptivity of the outer wall of the above-ground gas storage device, W s It is the local solar radiation power.

[0080] Preferably, in step S3, the gas storage device exchanges heat with the outside world throughout the entire working cycle of the compressed air energy storage power station. The direction of heat transfer depends on the temperature of the gas inside the storage device and the temperature of the storage device wall. During energy storage, the energy entering the storage device equals the change in the internal thermodynamic energy of the storage device plus the heat exchange with the outside world. During the resting process, the change in the internal thermodynamic energy of the storage device equals the heat exchange with the outside world. During energy release, the change in the internal thermodynamic energy of the storage device equals the energy flowing out of the storage device plus the heat exchange with the outside world. The energy equations for each of the above processes are as follows:

[0081]

[0082] Where dU is the change in thermodynamic energy within the gas storage device within a certain time step, and h i It is the specific enthalpy of the gas exchanged between the i-th gas storage device and the outside environment within that time step, dm i δQ is the mass flow rate of the i-th gas stream at that time step, and δQ is the heat exchanged between the gas storage device and the outside environment at that time step. Typically, the number of channels for gas exchange between the gas storage device and the outside environment in a compressed air energy storage power station is 1. The energy equation can be simplified based on this, and subsequent embodiments will be shown in the simplified form.

[0083] Furthermore, based on relevant thermodynamic theories, the basic energy equation within the air storage device during the operation of a compressed air energy storage power station within a unit time step is obtained as follows:

[0084]

[0085] Among them, u τ+dτ dτ is the specific thermodynamic energy of the air inside the gas storage device at time τ+dτ; dτ is the time step; m τ The mass of air inside the gas storage device at time τ; u τ q is the specific thermodynamic energy of the air inside the gas storage device at time τ; m h is the intake / exhaust flow rate during the energy storage phase at time τ. τ T is the specific enthalpy of the intake / exhaust during the energy storage phase at time τ; A is the internal surface area of ​​the gas storage device, and T is the specific enthalpy of the intake / exhaust during the energy storage phase. s It refers to the ambient temperature, T. a R is the temperature of the air inside the gas storage device. eq It is the equivalent thermal resistance between the inside of the gas storage device and the external environment.

[0086] Applying the ideal gas law and related parameters and theorems to formula (10) will lead to a large error because the operating conditions of the gas inside the compressed air energy storage device do not conform to the application range of the ideal gas law. The ideal gas law can be applied to real gases under high temperature and low pressure conditions, but the pressure of the gas inside the storage device is generally tens to hundreds of atmospheres. Therefore, the air state parameters under different conditions are obtained using REFPROP property database data as input for solving formula (10).

[0087] In formula (10), the state parameters of air are functions of temperature and pressure, and there is no explicit functional relationship. Therefore, an analytical solution cannot be directly obtained from formula (10). To achieve a high-precision solution, formula (10) needs to be discretized, and a discretized unsteady flow energy equation for the internal unsteady flow of the gas storage device needs to be established, using the following formula:

[0088]

[0089] m j+1 =m j +q m,j ·Δτ (12)

[0090] v j+1 =V / m j+1 (13)

[0091] Among them, u j+1 It is the specific thermodynamic energy of the air inside the gas storage device at time step j+1, m j It is the air quality inside the gas storage device at time step j, uj q is the specific thermodynamic energy of the air inside the gas storage device at time step j. m,j It is the gas mass flow rate, positive for filling and negative for releasing, h j T is the specific enthalpy of the gas being charged / de-charged at time step j, A is the surface area of ​​the inner wall of the gas storage device, and T is the specific enthalpy of the gas being charged / de-charged at time step j. a,j T is the internal air temperature of the gas storage device at time step j. i＝1,j Let be the temperature of the first layer of surrounding rock mesh in contact with the wall of the gas storage device at time step j, h be the forced convection heat transfer coefficient of the air inside the gas storage device, d be the mesh step size, λ1 be the thermal conductivity of the wall material or rock layer in contact with the air, and Δτ be the time step. According to (11)~(13), the specific thermodynamic energy u of the air inside the gas storage device at time step j+1 can be calculated from the known parameters at time step j. j+1 and specific volume v j+1 Then, based on the REFPROP property database data, other state parameters of the air at the (j+1)th time step can be calculated, including temperature, pressure, etc.

[0092] It should be explained that the inputs of formulas (11) to (13) include the temperature of the external environment at the j-th time step, i.e., T. i＝1,j In order to solve T i＝1,j This requires calculations based on the unsteady-state heat transfer models of different types of gas storage devices and their external environments in S2. The mesh space begins at the fluid heat transfer boundary inside the gas storage device and ends at the steady-state temperature in the external environment. Solving for T... i＝1,j At time step j-1, starting from the first grid, calculate the heat exchange between each grid and its neighboring grids, and calculate the net heat exchange. Based on the thermophysical properties of the materials in the grid, calculate the temperature change of the corresponding grid. Specifically, the temperature of the i-th grid at time step j is T. i,j The temperature at time step j-1 is T i,j-1 The neighboring grids are the (i-1)th and (i+1)th grids, and their temperatures at time step j are T and T, respectively. i-1,j and T i+1,j .

[0093] Preferably, in step S4, the initial cycle calculation step for the compressed air energy storage power station's gas storage device is as follows:

[0094] S4.1: When the compressed air energy storage power station is first charged to the rated maximum pressure, the time to reach the rated maximum pressure is calculated according to steps S2 and S3, the energy storage duration of the first cycle is determined, and the transient operating parameters of each time step within the energy storage duration are recorded, including the gas state parameters inside the gas storage device, the temperature distribution of the wall material and the external environment.

[0095] S4.2: The transient operating parameters at the end of the first cycle energy storage stage are used as the initial and boundary conditions for calculating the gas state parameters inside the gas storage device during the resting stage. Then, the changes in the gas state parameters inside the gas storage device are calculated through S2 and S3. During the resting stage, the gas mass flow rate of the gas storage device is 0. The transient operating parameters at each time step of the resting time are recorded.

[0096] S4.3: The transient operating parameters at the end of the settling phase serve as the initial and boundary conditions for calculating the internal gas state parameters of the gas storage device during the energy release phase. During the calculation, the transient operating parameters of the gas storage device at each time step also synchronously affect the exhaust parameters of that transient phase. The end point of the energy release phase is the rated minimum pressure. When the gas pressure inside the gas storage device reaches the rated minimum pressure, the time to reach the rated minimum pressure is recorded to determine the energy release duration of the first cycle, and the transient operating parameters at each time step during the energy release phase are recorded.

[0097] S4.4: Calculate the transient operating parameters for each time step of the resting phase after the energy release phase ends, as in step (2), and use them as the initial and boundary conditions for the next cycle.

[0098] S4.5: Repeat steps S4.1 to S4.4 to calculate the transient operating parameters for multiple cycles. Record the operating parameters such as energy storage duration, energy release duration, highest temperature during the energy storage stage, lowest temperature during the energy storage stage, highest temperature during the energy release stage, and lowest temperature during the energy release stage in each cycle. Use time series analysis to determine the stable operating conditions of each operating parameter when they reach a steady state.

[0099] Specifically, in step S4, during the initial running time, the state parameters of the air inside the gas storage device are the same as those of the external environment. Starting from this time, iterative calculations are performed using the discretized solution model in S2 and S3. This calculation is the first cycle of the compressed air energy storage power station's gas storage device and does not represent the rated operating conditions of the power station. The calculation results of the first cycle are used as the initial conditions and boundary conditions for the next cycle calculation.

[0100] Specifically, from the j-th time step to the j+1-th time step, the temperature of the gas inside the gas storage device at the j+1-th time step is calculated according to formulas (11) to (13). Then, as a boundary condition, the influence of the external environment of different gas storage devices on the temperature of the first layer of grid on the inner wall of the gas storage device at the j+1-th time step is analyzed according to formulas (1) to (8), and the temperature of the inner wall of the gas storage device at the j+1-th time step is calculated.

[0101] Specifically, the temperature of the inner wall of the gas storage device at the (j+1)th time step is used as a boundary condition and input into formulas (9) to (11) to obtain the state parameters of the gas inside the gas storage device at the (j+2)th time step. Then, the iterative calculation is repeated to obtain the temperature of the inner wall of the gas storage device at the (j+2)th time step.

[0102] Specifically, in this embodiment, the method for determining the stable cyclic operation condition of a compressed air energy storage power station according to this application is applied, and the results are displayed using the preliminary design parameters of a compressed air energy storage power station project, such as... Figure 2-5 As shown.

[0103] The operating conditions of the underground gas storage unit change over time from the first cycle as follows: Figure 2 As shown, the trends of the highest and lowest stable circulation temperatures of the underground gas storage device over time are as follows: Figure 3 As shown.

[0104] Specifically, Figure 2 During the initial filling process of the underground gas storage device, the internal air temperature gradually increases. However, in the latter half of the filling process, the temperature increase slows down. This is mainly because, as the mass of gas inside the storage device gradually increases during the latter half of filling, the enthalpy of the air entering the storage device per unit time step remains constant. This means that the increase in thermodynamic energy per unit time step inside the storage device remains constant, but due to the increase in the mass of gas inside the storage device, the rate of increase in specific thermodynamic energy decreases, corresponding to a gradual decrease in temperature. During the settling phase, the internal temperature of the storage device decreases, indicating that there is significant heat exchange between the underground gas storage device and the surrounding rock strata. In subsequent cycles, the average temperature of the air inside the storage device gradually decreases and gradually approaches a steady state. Figure 3 In the analysis of the highest and lowest temperatures of each working cycle, the compressed air energy storage power station gradually stabilized after 10 working cycles, reaching a stable cyclic operation condition. Under this condition, the highest temperature inside the gas storage device was 310K and the lowest temperature was 290K.

[0105] The operating conditions of the above-ground gas storage unit change over time from the first cycle as follows: Figure 4 As shown, the trends of the highest and lowest stable circulation temperatures of the above-ground gas storage device over time are as follows: Figure 5 As shown.

[0106] Specifically, Figure 4 During the initial inflation process of the above-ground gas storage device, the internal air temperature rises rapidly, with a rate and magnitude higher than [previous events]. Figure 2The underground gas storage device operates on a near-adiabatic basis. This is primarily because, under normal conditions, the average surface heat transfer coefficient of the fluid flowing over the horizontal tube or sphere is relatively small. Consequently, the heat exchange between the gas storage device and the external environment is low throughout the entire energy storage process, and the temperature remains essentially unchanged during the static phase. In subsequent cycles, the average temperature of the air inside the gas storage device gradually decreases and approaches a stable state. Figure 5 In the analysis of the highest and lowest temperatures of each working cycle, the compressed air energy storage power station gradually stabilized after 20 working cycles, reaching a stable cyclic operation condition. Under this condition, the highest temperature inside the gas storage device was 325K and the lowest temperature was 300K.

[0107] Other components and operations of the method for determining the stable cyclic operation condition of the compressed air energy storage power station's gas storage device according to an embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0108] To achieve the above or other objectives, the present invention also discloses an electronic device that stores the method for determining the stable cyclic operating conditions of the gas storage device described above.

[0109] The present invention relates to a method for determining the stable cyclic operating conditions of a compressed air energy storage system and an electronic device thereof. Taking the initial conditions and boundary parameters of the first cycle as input, an unsteady flow energy equation for the gas storage device is established, which couples the unsteady heat conduction between the internal and external environments of the gas storage device. Through multiple iterative calculations, the stable cyclic operating conditions of the compressed air energy storage power station can be determined relatively accurately. The parameter range of the stable cyclic operating conditions of the energy storage power station can be preliminarily determined in the early preliminary design stage, providing theoretical and data support for power station design and material selection.

[0110] This application adopts a thermodynamic simulation modeling method for the energy storage-release cycle of compressed air energy storage system gas storage device that takes into account environmental energy exchange and inlet parameter fluctuations. It proposes a method for determining the stable cycle operating conditions of the gas storage device, which is of great significance for improving the overall system performance and ensuring long-term stable operation.

[0111] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0112] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for determining the stable cyclic operating condition of a gas storage device, applied to the gas storage device of a compressed air energy storage power station; characterized in that: The steps are as follows: S1: Collect preliminary design parameters and initial operating parameters of the compressed air energy storage power station; S2: Based on the type of gas storage device, establish an unsteady heat conduction model between the inside of the gas storage device and the external environment; S3: Construct the unsteady flow energy equation of the gas storage device coupled with the unsteady heat conduction model of the external environment, establish the solution model of the operating condition parameters of the gas storage device, and determine the boundary conditions; The unsteady flow energy equation for the gas storage device coupled with the unsteady heat conduction model of the external environment in step S3 is as follows: （9） （10） （11） in, It is the specific thermodynamic energy of the air inside the gas storage device at time step j+1. It is the air quality inside the gas storage device at time step j. q is the specific thermodynamic energy of the air inside the gas storage device at time step j. m,j This is the gas mass flow rate; positive for filling and negative for releasing. T is the specific enthalpy of the gas being charged / discharged at time step j, A is the surface area of ​​the inner wall of the gas storage device, and T is the specific enthalpy of the gas being charged / discharged at time step j. a,j It is the internal air temperature of the gas storage device at time step j. Let be the temperature of the first layer of surrounding rock mesh in contact with the wall of the gas storage device at time step j, h be the forced convection heat transfer coefficient of the air inside the gas storage device, and d be the mesh step size. It is the thermal conductivity of the wall material or rock stratum that is in contact with air. It is the time step; S4: The discretization method is used to solve the gas storage device operating condition parameter solution model established in step S3. The first cycle is calculated from the initial operating time. Then, the transient operating condition parameter change characteristics of each subsequent time step are iteratively calculated. Time series analysis is then used to determine the stable cycle operating condition. In step S4, the initial cycle calculation steps for the compressed air energy storage power station's gas storage device are as follows: S4.1: When the compressed air energy storage power station is first charged to the rated maximum pressure, the time to reach the rated maximum pressure is calculated based on S2 and S3, the energy storage duration of the first cycle is determined, and the transient operating parameters of each time step within the energy storage duration are recorded, including the gas state parameters inside the gas storage device, the temperature distribution of the wall material and the external environment. S4.2: The transient operating parameters at the end of the first cycle energy storage stage are used as the initial and boundary conditions for calculating the gas state parameters inside the gas storage device during the resting stage. Then, the changes in the gas state parameters inside the gas storage device are calculated through S2 and S3. During the resting stage, the gas mass flow rate of the gas storage device is 0. The transient operating parameters at each time step of the resting time are recorded. S4.3: The transient operating parameters at the end of the settling phase serve as the initial and boundary conditions for calculating the gas state parameters inside the gas storage device during the energy release phase. During the calculation, the transient operating parameters of the gas storage device at each time step also synchronously affect the exhaust parameters of that transient phase. The end point of the energy release phase is the rated minimum pressure. When the gas pressure inside the gas storage device reaches the rated minimum pressure, the time to reach the rated minimum pressure is recorded to determine the energy release duration of the first cycle, and the transient operating parameters at each time step during the energy release phase are recorded. S4.4: Calculate the transient operating parameters for each time step of the resting phase after the energy release phase ends, as in step (2), and use them as the initial and boundary conditions for the next cycle. S4.5: Repeat steps S4.1 to S4.4 to calculate the transient operating parameters for multiple cycles. Record the operating parameters for each cycle, including energy storage duration, energy release duration, highest temperature during energy storage, lowest temperature during energy storage, highest temperature during energy release, and lowest temperature during energy release. Use time series analysis to determine the stable operating conditions of each operating parameter when they reach a steady state.

2. The method for determining the stable cyclic operating condition of the gas storage device according to claim 1, characterized in that: The preliminary design parameters in step S1 include air intake parameters, settling time, exhaust parameters, gas storage pressure limit, gas storage device volume, inner wall surface area, wall material parameters, and environmental parameters; the initial operating parameters include the initial gas pressure and temperature inside the gas storage device. The intake parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; and the environmental parameters include ambient temperature, thermal conductivity, or convective heat transfer coefficient.

3. The method for determining the stable cyclic operating condition of the gas storage device according to claim 2, characterized in that: The types of gas storage devices in step S2 include underground gas storage devices and above-ground gas storage devices. Underground gas storage devices include salt caverns and underground chambers, while above-ground gas storage devices include pipeline steel and high-pressure gas tanks. In the preliminary parameters of step S1, the wall material is determined according to the type of gas storage device and the preliminary actual plan. The wall material of the salt cave is the rock inside the cave, and the wall material of the underground chamber is steel lining and backfill concrete. The wall material of the above-ground gas storage device is steel, composite material and anti-corrosion coating.

4. The method for determining the stable cyclic operating condition of the gas storage device according to claim 3, characterized in that: In the preliminary parameters of step S1, the environmental parameters are related to the type of gas storage device; the environmental parameters of the underground gas storage device are the annual average temperature of the surrounding rock at the design site of the underground gas storage device and the thermal conductivity of the surrounding rock obtained through geological survey; the environmental parameters of the above-ground gas storage device are the local hourly historical average temperature, hourly surface solar radiation intensity, solar radiation absorptivity of the above-ground gas storage device and air convection heat transfer coefficient.

5. The method for determining the stable cyclic operating condition of the gas storage device according to claim 4, characterized in that: In step S2, the unsteady heat conduction model between the gas storage device and the external environment is meshed using a discretization method; the air inside the gas storage device only considers convective heat transfer near the wall. The wall material of the gas storage device is divided into grids according to the material of each layer: the outer side of the wall of the underground gas storage device is divided into grids along a rock layer of a specific length in the normal direction, with the characteristic length being 0.2-0.3 times the radius of the sphere corresponding to the equivalent volume of the underground gas storage device; the outer layer of the wall of the above-ground gas storage device adopts the average surface heat transfer coefficient of the fluid sweeping across the horizontal pipe or sphere.

6. The method for determining the stable cyclic operating condition of the gas storage device according to claim 4, characterized in that: In step S2, the unsteady-state heat transfer models between different types of gas storage devices and the external environment are shown below: The formula for the unsteady heat conduction model between the inside of a salt cavern gas storage device and the external environment is as follows: （1） （2） in, It is the temperature of rock mesh i at the j-th time step; It is the temperature of rock mesh i at the (j+1)th time step. It is the temperature of rock stratum grid i-1 at the j-th time step. d is the temperature of the rock stratum grid i+1 at the j-th time step, and d is the width of the rock stratum grid. It is the time step. It is the equivalent thermal resistance between rock layer grid i and rock layer grid i-1. is the equivalent thermal resistance between rock layer grid i and rock layer grid i+1, and h is the forced convection heat transfer coefficient of air; when i=1, it indicates that this is the first rock layer in the salt cave that is in contact with air. The unsteady-state heat transfer model between the interior and external environment of an artificially excavated underground gas storage device is based on the following formula: （3） （4） （5） in, It is the temperature of the grid i of the wall material and the rock strata as a whole at the j-th time step; It represents the temperature of the grid i of the wall material and the rock strata at the (j+1)th time step. It is the temperature of the grid i-1 of the wall material and the rock strata at the j-th time step. d is the temperature of the overall grid of the wall material and rock strata at time step i+1, and d is the grid width of the overall grid of the wall material and rock strata. It is the time step. It is the equivalent thermal resistance between grid i of the wall material and the rock strata as a whole and grid i-1 of the wall material and the rock strata as a whole. is the equivalent thermal resistance between grid i of the wall material and the overall rock stratum and grid i+1 of the wall material and the overall rock stratum; h is the forced convection heat transfer coefficient of air; n is the amount of wall material; m is the order of the wall material in a certain layer from the inside to the outside; l k Let be the thickness of the k-th type of wall material. When i=1, it indicates that this is the first layer of wall material in contact with the air inside the underground cavern. The unsteady-state heat conduction model between the pipeline steel and the internal environment of the high-pressure gas storage tank and the external environment is adopted using the following formula: （6） （7） （8） in, It is the temperature of the wall material mesh i at the j-th time step; It is the temperature of the wall material mesh i at the (j+1)th time step. It is the temperature of the wall material mesh i-1 at the j-th time step. d is the temperature of the wall material mesh at time step i+1, and d is the width of the wall material mesh. It is the time step. It is the equivalent thermal resistance between grid i of the wall material and grid i-1 of the wall material. is the equivalent thermal resistance between grid i and grid i+1 of the wall material, and h is the forced convection heat transfer coefficient of the air. s It refers to the average surface heat transfer coefficient of the outer side of the wall based on the fluid flowing over the horizontal tube or sphere; n is the amount of wall material, m is the order of the wall material in a certain layer from the inside to the outside, and l k Let be the thickness of the k-th type of wall material. When i=1, it indicates that this is the first layer of wall material in contact with air inside the above-ground gas storage device. It is the solar radiation absorptivity of the outer wall of the above-ground gas storage device, W. s It is the local solar radiation power.

7. The method for determining the stable cyclic operating condition of the gas storage device according to claim 6, characterized in that: In step S4, from the j-th time step to the (j+1)-th time step, the temperature of the gas inside the gas storage device at the (j+1)-th time step is calculated according to formulas (9) to (11). Then, as a boundary condition, the influence of the external environment of the gas storage device on the temperature of the first layer of grid on the inner wall of the gas storage device at the (j+1)-th time step is analyzed according to formulas (1) to (8), and the temperature of the inner wall of the gas storage device at the (j+1)-th time step is calculated. The temperature of the inner wall of the gas storage device at the (j+1)-th time step is used as a boundary condition and input into formulas (9) to (11) to obtain the state parameters of the gas inside the gas storage device at the (j+2)-th time step.

8. An electronic device, characterized in that: The storage device contains a method for determining the stable cyclic operating conditions of the gas storage device according to any one of claims 1-7.

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