Method for determining stable circulation working condition of gas storage device and electronic equipment

Abstract

The invention provides a method for determining the stable circulation working condition of an air storage device and electronic equipment. The method is applied to the air storage device of a compressed air energy storage power station. The method comprises the following steps: S1, collecting initial design parameters and initial operation parameters of the compressed air energy storage power station; s2, according to the type of the gas storage device, establishing an unsteady heat conduction model between the interior of the gas storage device and the external environment; s3, constructing a gas storage device unsteady-state flow energy equation coupled with the external environment unsteady-state heat conduction model, establishing a gas storage device operation condition parameter solving model, and determining boundary conditions; and S4, solving the gas storage device operation condition parameter solving model established in the step S3 by adopting a discretization method to obtain a first cycle of calculation from initial operation time, then iteratively calculating transient condition parameter change characteristics of subsequent time steps, and further determining a stable cycle condition by adopting time sequence analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and particularly to a method for determining the stable cycle condition of a gas storage device of a compressed air energy storage system, and an electronic device. Background Art

[0002] In the preliminary design stage of a compressed air energy storage power station, determining the stable cycle condition of the gas storage device of the compressed air energy storage power station is one of the prerequisites for realizing 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 stage, and release energy through air expansion work during the energy release stage. Therefore, the condition of the gas storage device during the stable cycle of the compressed air energy storage power station is of great significance for determining the power station system scheme and controlling the energy storage - energy release cycle. However, due to the influence of various factors such as environmental temperature changes, system design parameters, heat loss, and operating conditions, the rated condition of the gas storage device in the system scheme proposed in the preliminary design stage often cannot reflect the actual stable cycle condition of the system operation, which is not conducive to improving the overall performance and long-term stable operation of the compressed air energy storage power station. In addition, determining the stable cycle condition is also of great significance for the design, construction, and operation and maintenance of the gas storage device. In particular, the temperature range under the stable cycle condition involves the performance requirements of the wall material of the gas storage device. Summary of the Invention

[0003] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for determining the stable cycle condition of a gas storage device of a compressed air energy storage system, and an electronic device, which are used to determine the stable condition of the gas storage device of a compressed air energy storage power station from the initial state to the final realization of stable cycle operation, as a reference basis for the design, construction, and operation and maintenance of the compressed air energy storage power station.

[0004] To achieve the above purpose and other related purposes, the present invention provides a method for determining the stable cycle condition of a gas storage device, which is applied to the gas storage device of a compressed air energy storage power station; the steps are as follows:

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

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

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

[0008] S4: Solve the operating condition parameter solution model of the gas storage device established in step S3 by using a discretization method to obtain the transient condition parameter change characteristics of the first cycle calculated from the initial operating time and then iteratively calculate the subsequent individual time steps, and further use time series analysis to determine the stable cycle condition.

[0009] Preferably, the preliminary design parameters in step S1 include intake parameters, static duration, 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 pressure and temperature of the gas inside the gas storage device; among them, the intake parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; the environmental parameters include environmental 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, where 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 storage tanks; 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 wall material of the salt cavern is the rock of the cave inner wall, 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.

[0011] Preferably, the environmental parameters in the preliminary parameters of step S1 are related to the type of gas storage device; among them, 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 location obtained through geological exploration and the thermal conductivity of the surrounding rock at that location; the environmental parameters of the above-ground gas storage device are the historical average hourly temperature of the local ground, the hourly solar radiation intensity on the ground surface, the solar radiation absorption ratio of the above-ground gas storage device, and the air convective heat transfer coefficient.

[0012] Preferably, in step S2, a discretization method is used for grid division in the unsteady heat conduction model between the inside of the gas storage device and the external environment; only the convective heat transfer near the wall surface is considered for the air inside the gas storage device; the wall material of the gas storage device is divided into grids according to each layer of material: for the outer wall of the underground gas storage device, a rock layer with a specific normal length is taken for grid division, and the characteristic length is 0.2 - 0.3 times the radius of the sphere corresponding to the equivalent volume of the underground gas storage device; the outer wall of the above-ground gas storage device uses the average surface heat transfer coefficient of fluid flowing over a horizontal tube or a sphere.

[0013] Preferably, in step S2, the unsteady heat conduction models between different types of gas storage devices and the external environment are as follows: The formula for the unsteady 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 is the temperature of rock formation grid i at the j-th time step; T i,j+1 is the temperature of rock formation grid i at the (j + 1)-th time step, T i-1,j is the temperature of rock formation grid i - 1 at the j-th time step, T i+1,j is the temperature of rock formation grid i + 1 at the j-th time step, d is the width of the rock formation grid, Δτ is the time step, r i-1 is the equivalent thermal resistance between rock formation grid i and rock formation grid i - 1, r i+1 is the equivalent thermal resistance between rock formation grid i and rock formation grid i + 1, h is the forced convection heat transfer coefficient of air; when i = 1, it means that this is the first layer of rock formation in contact with air inside the salt cavern;

[0017] The unsteady heat conduction model between the inside of the underground chamber gas storage device excavated manually and the external environment adopts the following formula:

[0018]

[0019]

[0020]

[0021] Among them, T i,j is the temperature of grid i of the wall material and the whole rock formation at the j-th time step; T i,j+1 is the temperature of grid i of the wall material and the whole rock formation at the (j + 1)-th time step, T i-1,j is the temperature of grid i - 1 of the wall material and the whole rock formation at the j-th time step, T i+1,j is the temperature of grid i + 1 of the wall material and the whole rock formation at the j-th time step, d is the width of the grid of the wall material and the whole rock formation, Δτ is the time step, r i-1 is the equivalent thermal resistance between grid i of the wall material and the whole rock formation and grid i - 1 of the wall material and the whole rock formation, r i+1 is the equivalent thermal resistance between grid i of the wall material and the whole rock formation and grid i + 1 of the wall material and the whole rock formation, h is the forced convection heat transfer coefficient of air; n is the number of wall materials, m is the sorting of a certain layer of wall materials from the inside to the outside, l k is the thickness of the k-th wall material, when i = 1, it means that this is the first layer of wall material in contact with air inside the underground chamber;

[0022] The unsteady heat conduction model between the inside of the pipeline steel and high-pressure gas storage tank gas storage device and the external environment adopts the following formula:

[0023]

[0024]

[0025]

[0026] Among them, T i,j is the temperature of the grid i of the wall material at the j-th time step; T i,j+1 is the temperature of the grid i of the wall material at the (j + 1)-th time step, T i-1,j is the temperature of the grid i - 1 of the wall material at the j-th time step, T i+1,j is the temperature of the grid i + 1 of the wall material at the j-th time step, d is the grid width of the wall material, Δτ is the time step, r i-1 is the equivalent thermal resistance between the grid i of the wall material and the grid i - 1 of the wall material, r i+1 is the equivalent thermal resistance between the grid i of the wall material and the grid i + 1 of the wall material, h is the forced convection heat transfer coefficient of air, h s is the average surface heat transfer coefficient of the outer wall surface according to the fluid flowing over a horizontal tube or a sphere; n is the number of wall materials, m is the sorting of the wall materials of a certain layer from the inside to the outside, l k is the thickness of the k-th wall material. When i = 1, it means that this is the first layer of wall material in the above-ground gas storage device in contact with air. α is the solar radiation absorptivity of the outer wall surface of the above-ground gas storage device, W s 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 is the specific thermodynamic energy of the air inside the gas storage device at the (j + 1)-th time step, m j is the mass of the air inside the gas storage device at the j-th time step, u j is the specific thermodynamic energy of the air inside the gas storage device at the j-th time step, q m,j is the gas mass flow rate, positive for charging and negative for discharging, h jis the specific enthalpy of the gas during charging / discharging at the j-th time step, A is the inner surface area of the energy storage device, T a,j is the internal air temperature of the energy storage device at the j-th time step, T i＝1,j is the temperature of the first layer of surrounding rock grid in contact with the wall of the energy storage device at the j-th time step, h is the forced convection heat transfer coefficient of the internal air in the energy storage device, d is the grid step, λ1 is the thermal conductivity of the wall material or rock formation 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 energy storage device at the j+1-th time step is solved according to formulas (9) to (11), and then used as a boundary condition. According to formulas (1) to (8), the influence of different external environments of the energy storage device at the j+1-th time step on the temperature of the first layer of grid on the inner wall surface of the energy storage device is analyzed, and the temperature of the inner wall surface of the energy storage device at the j+1-th time step is solved. The temperature of the inner wall surface of the energy storage device at the j+1-th time step is used as a boundary condition and input into formulas (9) to (11), and the state parameters of the gas inside the energy storage device at the j+2-th time step can be solved.

[0033] Preferably, in step S4, the first cycle calculation steps of the compressed air energy storage power station energy storage device are as follows:

[0034] S4.1: The compressed air energy storage power station is first charged to the rated maximum pressure. According to S2 and S3, calculate the time to reach the rated maximum pressure, determine the energy storage duration of the first cycle, and record the transient operating parameters at each time step during the energy storage duration, including the internal gas state parameters of the energy 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 conditions and boundary conditions for calculating the internal gas state parameters of the energy storage device during the static stage. Then, through S2 and S3, calculate the change of the internal gas state parameters of the energy storage device. The gas mass flow rate of the energy storage device during the static stage is 0, and record the transient operating parameters at each time step during the static duration.

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

[0037] S4.4: Calculate the transient condition parameters for each time step during the static stage after the end of the energy release stage according to step (2), and use them as the initial conditions and boundary conditions for the next cycle.

[0038] S4.5: Repeat steps S4.1 - S4.4 to calculate the transient condition parameters for multiple cycles, record the condition parameters such as energy storage duration, energy release duration, maximum temperature during the energy storage stage, minimum temperature during the energy storage stage, maximum temperature during the energy release stage, and minimum temperature during the energy release stage in each cycle. Use time series analysis to analyze the stability of each condition parameter and determine the stable cycle conditions.

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

[0040] As described above, a method for determining the stable cycle conditions of a gas storage device in a compressed air energy storage system and an electronic device according to the present invention have the following beneficial effects:

[0041] 1. Taking the initial conditions and boundary parameters of the first cycle as the input, the present invention establishes an unsteady flow energy equation of the gas storage device that couples the internal of the gas storage device and the external environment's unsteady heat conduction. Through multiple cycle iterations, it can more accurately determine the stable cycle conditions of the compressed air energy storage power station.

[0042] 2. For the long-term variable condition operation of the compressed air energy storage power station, compared with the rated condition, the determined stable cycle conditions can more accurately measure the capacity of the compressed air energy storage power station and characterize the energy storage - energy release characteristics of the normal operation of the power station.

[0043] 3. In the preliminary design stage, the parameter range of the stable cycle conditions of the energy storage power station can be initially determined, providing theoretical and data support for the power station design and material selection. Description of the Drawings

[0044] Figure 1 is a flowchart according to the specific implementation manner of the present application;

[0045] Figure 2 is a cycle condition diagram of the underground gas storage device starting from the first cycle in the specific implementation manner of the present application;

[0046] Figure 3 is a diagram of the maximum and minimum temperatures of the stable cycle of the underground gas storage device in the specific implementation manner of the present application;

[0047] Figure 4 is a stable cycle condition diagram of the above-ground gas storage device starting from the first cycle in the specific implementation manner of the present application;

[0048] Figure 5It is the graph of the highest and lowest temperatures during the stable cycle of the above-ground gas storage device in the specific implementation manner of this application. Specific implementation manner

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

[0050] It should be noted that the structures, proportions, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limited conditions under which the present invention can be implemented. Therefore, they do not have substantial technical significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration, and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope within which the present invention can be implemented.

[0051] As Figure 1 shown, the present invention provides a method for determining the stable cycle working conditions of a gas storage device, which is applied to the gas storage device in a compressed air energy storage power station; the steps are as follows:

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

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

[0054] S3: Construct an unsteady flow energy equation of the gas storage device that couples with the unsteady heat conduction model of the external environment, establish a solution model for the operation condition parameters of the gas storage device, and determine the boundary conditions;

[0055] S4: Solve the solution model for the operation condition parameters of the gas storage device established in step S3 by using a discretization method, obtain the change characteristics of the transient condition parameters from the initial operation time to calculate the first cycle, and then iteratively calculate the subsequent individual time steps, and further use time series analysis to determine the stable cycle working conditions.

[0056] The method for determining the stable cycling conditions of the gas storage device involved in the present invention first collects the preliminary design parameters and operating parameters of the compressed air energy storage power station, then constructs an unsteady heat conduction model between the interior of the gas storage device and the external environment, and then couples the unsteady heat conduction model into the energy flow equation of the gas storage device during 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 stable cycling condition parameters are determined through time series analysis of the condition parameters of the key nodes representing stable operation.

[0057] Preferably, in this embodiment, the preliminary design parameters in step S1 include intake parameters, static duration, 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 pressure and temperature of the gas inside the gas storage device; among them, the intake parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; the environmental parameters include environmental temperature, thermal conductivity, or convective heat transfer coefficient.

[0058] Preferably, in this embodiment, in the preliminary parameters of step S1, the wall material of the gas storage device is determined according to the type of the gas storage device and the preliminary actual scheme. The types of gas storage devices include underground gas storage devices and above-ground gas storage devices. Among them, 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 storage tanks; the wall material of the salt cavern is the rock on the inner wall of the cavern, and the wall material of the underground chamber is a steel lining and backfilled concrete; the wall material of the above-ground gas storage device is steel, composite material, and anti-corrosion coating.

[0059] Preferably, in this embodiment, in the preliminary parameters of step S1, the environmental parameters are the thermophysical parameters of the environment where the gas storage device is located. The environmental parameters are related to the type of the gas storage device. Among them, the environment where the underground gas storage device is located is the rock formation at a certain depth underground, and the environmental parameters are the annual average temperature and thermal conductivity of the underground rock formation at this depth, which are generally obtained through geological exploration methods. For above-ground gas storage devices, pipeline steel and high-pressure gas storage tanks are usually exposed to the air, so their environmental parameters are the average hourly ground temperature of the local area 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 surface of the gas storage device will absorb part of the solar radiation energy, and this part of the energy can be calculated by multiplying the absorptivity of the coating on the outer surface of the gas storage device by the local solar radiation power.

[0061] Preferably, in step S2, a discretization method is adopted for grid division in establishing the unsteady heat conduction model between the inside of the gas storage device and the external environment. For the heat exchange between the air inside the gas storage device and the external environment, three aspects need to be considered: the convective heat transfer from the air inside the gas storage device to the wall surface, the heat conduction through multiple layers of materials inside the wall surface, and the heat exchange between the wall surface and the external environment.

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

[0063] Furthermore, a discretization method is adopted for grid division in establishing the unsteady heat conduction model between the inside of the gas storage device and the external environment. Since the inside of the gas storage device bears high pressure, the wall material of the gas storage device has a certain thickness. A small length along the thickness direction is taken as the grid step size to divide the grid for heat transfer inside the wall material. The grid step size is 0.1 - 0.2 cm to achieve the heat conduction calculation of multiple layers of materials inside the wall surface. Since the external environment of the underground gas storage device is rock strata, when dividing the grid for the underground gas storage device, a specific length of rock strata needs to be taken along the normal direction of the wall surface of the gas storage device for grid division. The 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, a discretization method is adopted for grid division in establishing the unsteady heat conduction model between the inside of the gas storage device and the external environment. When the gas storage device is an above-ground gas storage device (pipeline steel, high-pressure gas storage tank), the grid needs to be divided for the wall material of the gas storage device. The average surface heat transfer coefficient outside the wall surface is based on the fluid flowing over a horizontal tube or a sphere.

[0065] Preferably, in step S2, the unsteady 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 formula for the unsteady heat conduction model between the inside of the salt cavern gas storage device and the external environment is as follows:

[0067]

[0068]

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

[0070] Second: When the gas storage device is an underground chamber, the unsteady heat conduction model between the inside 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 is the temperature of the grid i of the wall material and the whole rock formation at the j-th time step; T i,j+1 is the temperature of the grid i of the wall material and the whole rock formation at the (j + 1)-th time step, T i-1,j is the temperature of the grid i - 1 of the wall material and the whole rock formation at the j-th time step, T i+1,j is the temperature of the grid i + 1 of the wall material and the whole rock formation at the j-th time step, d is the width of the grid of the wall material and the whole rock formation, Δτ is the time step, r i-1 is the equivalent thermal resistance between the grid i of the wall material and the whole rock formation and the grid i - 1 of the wall material and the whole rock formation, r i+1 is the equivalent thermal resistance between the grid i of the wall material and the whole rock formation and the grid i + 1 of the wall material and the whole rock formation, h is the forced convection heat transfer coefficient of air; n is the number of wall materials, m is the sorting of a certain layer of wall materials from the inside out, l k is the thickness of the k-th wall material, when i = 1, it means that this is the first layer of wall material in the underground chamber in contact with air.

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

[0076]

[0077]

[0078]

[0079] wherein, T i,j is the temperature of grid i of the wall material at the j-th time step; T i,j+1 is the temperature of grid i of the wall material at the (j + 1)-th time step, T i-1,j is the temperature of grid i - 1 of the wall material at the j-th time step, T i+1,j is the temperature of grid i + 1 of the wall material at the j-th time step, d is the grid width of the wall material, Δτ is the time step, r i-1 is the equivalent thermal resistance between grid i of the wall material and grid i - 1 of the wall material, r i+1 is the equivalent thermal resistance between grid i of the wall material and grid i + 1 of the wall material, h is the forced convection heat transfer coefficient of air, h s is the average surface heat transfer coefficient of the outside of the wall according to the fluid flowing over a horizontal tube or a sphere; n is the number of wall materials, m is the sorting of a certain layer of wall materials from the inside to the outside, l k is the thickness of the k-th wall material. When i = 1, it means that this is the first layer of wall material in the above-ground gas storage device in contact with air; α is the solar radiation absorptivity of the outer wall of the above-ground gas storage device, W s is the local solar radiation power.

[0080] Preferably, in step S3, the gas storage device transfers heat to and from the outside during the entire working cycle of the compressed air energy storage power station, and the direction of heat transfer depends on the temperature of the gas inside the gas storage device and the temperature of the wall of the gas storage device. The energy entering the gas storage device during the energy storage process is equal to the change in the internal thermodynamic energy of the gas storage device and the heat exchanged with the outside. The change in the internal thermodynamic energy of the gas storage device during the static process is equal to the heat exchanged with the outside. The change in the internal thermodynamic energy of the gas storage device during the energy release process is equal to the energy flowing out of the gas storage device and the heat exchanged with the outside. The energy equations for the above processes are as follows:

[0081]

[0082] wherein, dU is the change in the internal thermodynamic energy of the gas storage device within a certain time step, h i is the specific enthalpy of the i-th gas storage device exchanging gas with the outside within this time step, dm i is the mass flow rate of the i-th gas within this time step, and δQ is the heat exchanged between the gas storage device and the outside within this time step. Usually, the number of channels for the gas storage device of the compressed air energy storage power station to exchange gas with the outside is 1, and the energy equation can be simplified accordingly. The subsequent embodiments will be shown in the simplified situation.

[0083] Furthermore, according to the relevant theories of thermodynamics, the basic energy equation inside the gas storage device during the operation of the compressed air energy storage power station within a unit time step is as follows:

[0084]

[0085] where u τ+dτ is the specific thermodynamic energy of the air inside the gas storage device at the moment of τ + dτ; dτ is the time step; m τ is the mass of the air inside the gas storage device at the moment of τ; u τ is the specific thermodynamic energy of the air inside the gas storage device at the moment of τ; q m is the intake / exhaust flow rate during the energy storage stage at the moment of τ; h τ is the specific enthalpy of the intake / exhaust during the energy storage stage at the moment of τ; A is the inner surface area of the gas storage device, T s is the external environmental temperature, T a is the air temperature inside the gas storage device, R eq is the equivalent thermal resistance between the inside of the gas storage device and the external environment.

[0086] Applying the ideal gas state equation and the related parameters and theorems of ideal gases in formula (10) will lead to large errors because the working conditions of the gas inside the gas storage device of the compressed air energy storage power station do not conform to the application range of the ideal gas state equation. Real gases can apply the ideal gas state equation under the conditions of high temperature and low pressure, but inside the gas storage device, the gas pressure is generally in the range of dozens to hundreds of atmospheres. Therefore, the air state parameters under different states are obtained using the data of the REFPROP physical property database as the input for solving formula (10).

[0087] The state parameters of the air in formula (10) 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 high-precision solution, formula (10) needs to be discretized, and a discretized unsteady flow energy equation inside the gas storage device is 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] where u j+1 is the specific thermodynamic energy of the air inside the gas storage device at the (j + 1)-th time step, m j is the mass of the air inside the gas storage device at the j-th time step, uj is the specific thermodynamic energy of the air inside the energy storage device at the j-th time step, q m,j is the gas mass flow rate, positive for charging and negative for discharging, h j is the specific enthalpy of the gas being charged / discharged at the j-th time step, A is the inner wall surface area of the energy storage device, T a,j is the air temperature inside the energy storage device at the j-th time step, T i＝1,j is the temperature of the first layer of surrounding rock grid in contact with the wall of the energy storage device at the j-th time step, h is the forced convection heat transfer coefficient of the air inside the energy storage device, d is the grid 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. According to (11) - (13), the specific thermodynamic energy u of the air inside the energy storage device at the (j + 1)-th time step can be calculated based on the known parameters at the j-th time step j+1 and the specific volume v j+1 , and then based on the data in the REFPROP property database, other state parameters of the air at the (j + 1)-th time step, including temperature, pressure, etc., can be calculated

[0092] It should be noted that the input of formulas (11) - (13) includes the temperature of the external environment at the j-th time step, that is, T i＝1,j . To solve for T i＝1,j , the calculation formulas of the unsteady heat conduction model between the inside and the external environment of different types of energy storage devices in S2 need to be used. The grid space starts from the fluid heat transfer boundary inside the energy storage device and ends at the stable temperature in the external environment. When solving for T i＝1,j , starting from the temperature of each node in the grid at the (j - 1)-th time step, starting from the first grid, calculate the heat exchange amount between each grid and its adjacent grids, calculate the net heat exchange amount, and calculate the temperature change of the corresponding grid according to the thermal physical properties of the substances in the grid. Specifically, the temperature of the i-th grid at the j-th time step is T i,j , and the temperature at the (j - 1)-th time step is T i,j-1 , and the adjacent grids are the (i - 1)-th and (i + 1)-th grids, and the temperatures at the j-th time step are T i-1,j and T i+1,j respectively

[0093] Preferably, in step S4, the first cycle calculation steps of the compressed air energy storage power station energy storage device are as follows:

[0094] S4.1: The compressed air energy storage power station is initially charged to the rated maximum pressure. According to steps S2 and S3, calculate the time to reach the rated maximum pressure, determine the energy storage duration of the first cycle, and record the transient operating parameters at each time step during the energy storage duration, including the internal gas state parameters of the energy storage device, the temperature distributions of the wall material and the external environment

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

[0096] S4.3: The transient operating condition parameters at the end of the static stage are used as the initial conditions and boundary conditions for calculating the internal gas state parameters of the gas storage device during the energy release stage. During the calculation process, the transient operating condition parameters of the gas storage device at each time step also synchronously affect the exhaust parameters of that transient. The end point of the energy release stage is the rated minimum pressure. When the gas pressure in the gas storage device reaches the rated minimum pressure, record the time when the rated minimum pressure is reached, determine the energy release duration of the first cycle, and record the transient operating condition parameters at each time step during the energy release stage.

[0097] S4.4: Calculate the transient operating condition parameters at each time step of the static stage after the end of the energy release stage according to step (2), and use them as the initial conditions and boundary conditions for the next cycle.

[0098] S4.5: Repeat steps S4.1 to S4.4 to calculate the transient operating condition parameters of multiple cycles, record the operating condition parameters such as the energy storage duration, energy release duration, maximum temperature during the energy storage stage, minimum temperature during the energy storage stage, maximum temperature during the energy release stage, and minimum temperature during the energy release stage in each cycle. Use time series analysis to analyze the stability of each operating condition parameter and determine the stable cycle operating condition.

[0099] Specifically, in step S4, at the initial operating 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 discretization solution model in S2 and S3. This calculation is the first cycle of the gas storage device of the compressed air energy storage power station and does not represent the rated operating condition 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 solved according to formulas (11) to (13), and then used as the boundary condition. According to formulas (1) to (8), analyze the influence of the external environment of different gas storage devices at the (j + 1)-th time step on the temperature of the first layer of grid on the inner wall surface of the gas storage device, and solve the temperature of the inner wall surface of the gas storage device at the (j + 1)-th time step.

[0101] Specifically, the inner wall temperature of the gas storage device at the (j + 1)-th time step is used as the boundary condition and input into formulas (9) to (11), and the state parameters of the gas inside the gas storage device at the (j + 2)-th time step can be solved. Then, iterative calculations are repeated to obtain the inner wall temperature 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 the compressed air energy storage power station of the present application is applied, and the results are presented through the preliminary design parameters of a certain compressed air energy storage power station project, as Figures 2 - 5 shown.

[0103] The cyclic condition of the underground gas storage device starting from the first cycle changes with time as Figure 2 shown, and the variation trends of the highest and lowest temperatures of the stable cycle of the underground gas storage device with time are as Figure 3 shown.

[0104] Specifically, Figure 2 in the first cycle of the underground gas storage device, the internal air temperature gradually increases during the charging process. However, in the second half of the charging process, the temperature increase gradually slows down. This is mainly because as the gas mass inside the gas storage device gradually increases in the second half of the charging process, but the enthalpy value of the air entering the gas storage device per unit time step remains unchanged, which means that the increment of the internal energy per unit time step of the gas storage device remains unchanged. However, due to the increase in the gas mass on the inner wall of the gas storage device, the increase rate of the specific internal energy decreases, and the corresponding temperature gradually decreases. During the static stage, the internal temperature of the gas storage device decreases, indicating that there is a relatively obvious heat exchange between the underground gas storage device and the surrounding rock formations. In subsequent cycles, the average temperature of the air inside the gas storage device gradually decreases and gradually approaches the stable state. Figure 3 in the highest and lowest temperatures of each working cycle are analyzed. After 10 working cycles of the compressed air energy storage power station, the inside of the gas storage device gradually stabilizes and reaches the stable cyclic operation condition. Under this condition, the highest temperature inside the gas storage device is 310 K, and the lowest temperature is 290 K.

[0105] The cyclic condition of the above-ground gas storage device starting from the first cycle changes with time as Figure 4 shown, and the variation trends of the highest and lowest temperatures of the stable cycle of the above-ground gas storage device with time are as Figure 5 shown.

[0106] Specifically, Figure 4 in the first cycle of the above-ground gas storage device, the internal air temperature rises rapidly during the charging process, and the rising rate and amplitude are higher than those of Figure 2The underground gas storage device approximates an adiabatic process. This is mainly because under normal conditions of the external environment, the average surface heat transfer coefficient of the fluid flowing over a horizontal tube or sphere is small, and the amount of heat exchange between the inside of the gas storage device and the external environment during the entire energy storage process is low. At the same time, it is manifested that the temperature remains basically unchanged during the static stage. In subsequent cycles, the average temperature of the air inside the gas storage device gradually decreases and gradually approaches a stable state. Figure 5 Among them, the highest and lowest temperatures of each working cycle are analyzed. After 20 working cycles of the compressed air energy storage power station, the inside of the gas storage device gradually stabilizes and reaches a stable cycle operation condition. Under this condition, the highest temperature inside the gas storage device is 325K, and the lowest temperature is 300K.

[0107] Other components and operations of the method for determining the stable cycle operation condition of the gas storage device of a compressed air energy storage power station according to the embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail here.

[0108] To achieve the above object or other objects, the present invention also discloses an electronic device that stores the above method for determining the stable cycle condition of the gas storage device.

[0109] The method for determining the stable cycle operation condition of the gas storage device of the compressed air energy storage system and the electronic device involved in the present invention take the initial conditions and boundary parameters of the first cycle as inputs, establish an unsteady flow energy equation of the gas storage device that couples the unsteady heat conduction inside the gas storage device and the external environment, and can accurately determine the stable cycle operation condition of the compressed air energy storage power station through multiple cycle iteration calculations; the parameter range of the stable cycle operation condition of the energy storage power station can be initially determined in the preliminary design stage, providing theoretical and data support for power station design and material selection.

[0110] This application adopts a thermodynamics simulation modeling method for the energy storage-discharge cycle of the gas storage device of a compressed air energy storage system that considers environmental energy exchange and inlet parameter fluctuations, and proposes a method for determining the stable cycle operation condition of the gas storage device, which is of great significance for improving the overall performance of the system and ensuring long-term stable operation.

[0111] Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0112] The above embodiments merely illustrate the principles and effects of the present invention and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for determining a stable cycling condition of a gas storage device, which is applied to the gas storage device in a compressed air energy storage power station; characterized in that: The steps are as follows: S1: Collect the preliminary design parameters and initial operation parameters of the compressed air energy storage power station; S2: Establish an unsteady heat conduction model between the inside of the gas storage device and the external environment according to the type of the gas storage device; S3: Construct an unsteady flow energy equation of the gas storage device that couples with the unsteady heat conduction model of the external environment, establish a solution model for the operation condition parameters of the gas storage device, and determine the boundary conditions; S4: Solve the solution model for the operation condition parameters of the gas storage device established in step S3 by using a discretization method to obtain the transient condition parameter change characteristics of the first cycle calculated from the initial operation time, and then iteratively calculate the subsequent individual time steps, and further use time series analysis to determine the stable cycle condition.

2. The method for determining the stable cycle condition of the gas storage device according to claim 1, wherein: The preliminary design parameters in step S1 include intake parameters, static duration, exhaust parameters, gas storage pressure limit, gas storage device volume, inner wall surface area, wall material parameters, and environmental parameters; the initial operation parameters include the initial pressure and temperature of the gas inside the gas storage device; Among them, the intake parameters include temperature, flow rate, and pressure; the exhaust parameters include flow rate; the wall material parameters include thickness and thermal conductivity; the environmental parameters include environmental temperature, thermal conductivity, or convective heat transfer coefficient.

3. The method for determining the stable cycle condition of the gas storage device according to claim 2, wherein: The types of gas storage devices in step S2 include underground gas storage devices and above-ground gas storage devices. Among them, 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 storage tanks; The wall material in the preliminary parameters of step S1 is determined according to the type of the gas storage device and the preliminary actual plan. The wall material of the salt cavern is the rock on the inner wall of the cavern, and the wall material of the underground chamber is the steel lining and backfilled 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 cycle condition of the gas storage device according to claim 3, wherein: The environmental parameters in the preliminary parameters of step S1 are related to the type of the gas storage device; among them, 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 location obtained through geological exploration and the thermal conductivity of the surrounding rock at this location; the environmental parameters of the above-ground gas storage device are the historical average hourly air temperature on the local ground, the hourly solar radiation intensity on the ground surface, the solar radiation absorption ratio of the above-ground gas storage device, and the air convective heat transfer coefficient.

5. The method for determining the stable cycle condition of the gas storage device according to claim 4, characterized in that: In step S2, a discretization method is used for grid division in the unsteady heat conduction model between the inside of the gas storage device and the external environment; only the convective heat transfer near the wall surface is considered for the air inside the gas storage device; The wall material of the gas storage device is divided into grids according to each layer of material: for the outer wall of the underground gas storage device, a rock layer with a specific normal length is taken for grid division, and the characteristic length is 0.2 - 0.3 times the radius of the sphere corresponding to the equivalent volume of the underground gas storage device; the outer wall of the above-ground gas storage device adopts the average surface heat transfer coefficient of the fluid flowing over a horizontal tube or a sphere.

6. The method for determining the stable cycling condition of the gas storage device according to claim 4, characterized in that: In step S2, the unsteady heat conduction models of different types of gas storage devices and the external environment are as follows: The formula for the unsteady heat conduction model between the inside of the salt cavern gas storage device and the external environment is as follows: Among them, T i,j is the temperature of the rock formation grid i at the j-th time step; T i,j+1 is the temperature of the rock formation grid i at the (j + 1)-th time step, T i-1,j is the temperature of the rock formation grid i - 1 at the j-th time step, T i+1,j is the temperature of the rock formation grid i + 1 at the j-th time step, d is the width of the rock formation grid, Δτ is the time step, r i-1 is the equivalent thermal resistance between the rock formation grid i and the rock formation grid i - 1, r i+1 is the equivalent thermal resistance between the rock formation grid i and the rock formation grid i + 1, h is the forced convection heat transfer coefficient of the air; when i = 1, it means that this is the first layer of rock formation in the salt cavern in contact with the air; The formula for the unsteady heat conduction model between the inside of the artificially excavated underground chamber gas storage device and the external environment is as follows: Among them, T i,j is the temperature of the grid i of the overall wall material and rock formation at the j-th time step; T i,j+1 is the temperature of the grid i of the overall wall material and rock formation at the (j + 1)-th time step, T i-1,j is the temperature of the grid i - 1 of the overall wall material and rock formation at the j-th time step, T i+1,j is the temperature of the grid i + 1 of the overall wall material and rock formation at the j-th time step, d is the grid width of the overall wall material and rock formation, Δτ is the time step, r i-1 is the equivalent thermal resistance between the grid i of the overall wall material and rock formation and the grid i - 1 of the overall wall material and rock formation, r i+1 is the equivalent thermal resistance between the grid i of the overall wall material and rock formation and the grid i + 1 of the overall wall material and rock formation, h is the forced convection heat transfer coefficient of air; n is the number of wall materials, m is the sorting of a certain layer of wall materials from the inside out, l k is the thickness of the k-th wall material. When i = 1, it indicates that this is the first layer of wall material in the underground chamber in contact with air; The formula for the unsteady heat conduction model between the inside of the pipeline steel and high-pressure gas storage tank gas storage device and the external environment is as follows: Among them, T i,j is the temperature of the grid i of the wall material at the j-th time step; T i,j+1 is the temperature of the grid i of the wall material at the (j + 1)-th time step, T i-1,j is the temperature of the grid i - 1 of the wall material at the j-th time step, T i+1,j is the temperature of the grid i + 1 of the wall material at the j-th time step, d is the grid width of the wall material, Δτ is the time step, r i-1 is the equivalent thermal resistance between the grid i of the wall material and the grid i - 1 of the wall material, r i+1 is the equivalent thermal resistance between the grid i of the wall material and the grid i + 1 of the wall material, h is the forced convection heat transfer coefficient of the air, h s is the average surface heat transfer coefficient of the fluid flowing over the horizontal tube or sphere outside the wall; n is the number of wall materials, m is the sorting of the wall materials of a certain layer from the inside to the outside, l k is the thickness of the k-th wall material. When i = 1, it means that this is the first layer of wall material in contact with the 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 is the local solar radiation power.

7. The method for determining the stable cycle condition of the gas storage device according to claim 6, wherein: In step S3, the unsteady flow energy equation of the gas storage device coupled with the unsteady heat conduction model of the external environment is as follows: m j+1 = m j + q m,j ·Δτ (10) v j+1 = V / m j+1 (11) where, u j+1 is the specific internal energy of the air inside the gas storage device at the (j + 1)-th time step, m j is the mass of the air inside the gas storage device at the j-th time step, u j is the specific internal energy of the air inside the gas storage device at the j-th time step, q m,j is the gas mass flow rate, positive for charging and negative for discharging, h j is the specific enthalpy of the gas for charging / discharging at the j-th time step, A is the inner wall surface area of the gas storage device, T a,j is the air temperature inside the gas storage device at the j-th time step, T i＝1,j is the temperature of the first layer of surrounding rock grid in contact with the wall of the gas storage device at the j-th time step, h is the forced convection heat transfer coefficient of the air inside the gas storage device, d is the grid step size, λ1 is the thermal conductivity of the wall material or rock formation in contact with the air, and Δτ is the time step size.

8. The method for determining the stable cycle condition of the gas storage device according to claim 7, characterized in that: In step S4, from the j-th time step to the j+1-th time step, according to formulas (9)-(11), the temperature of the gas inside the gas storage device at the j+1-th time step is solved, and then as the boundary condition, according to formulas (1)-(8), the influence of the external environment of different gas storage devices at the j+1-th time step on the temperature of the first layer of grid on the inner wall surface of the gas storage device is analyzed, and the temperature of the inner wall surface of the gas storage device at the j+1-th time step is solved; the temperature of the inner wall surface of the gas storage device at the j+1-th time step is used as the boundary condition and input into formulas (9)-(11), and the state parameters of the gas inside the gas storage device at the j+2-th time step can be solved.

9. The method for determining the stable cycle condition of the gas storage device according to claim 1, characterized in that: In step S4, the first cycle calculation steps of the gas storage device of the compressed air energy storage power station are as follows: S4.1: The compressed air energy storage power station is first inflated to the rated maximum pressure. According to S2 and S3, the time to reach the rated maximum pressure is calculated, the energy storage duration of the first cycle is determined, and the transient operating parameters at each time step during the energy storage duration are recorded, including the state parameters of the gas 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 energy storage stage of the first cycle are used as the initial conditions and boundary conditions for calculating the state parameters of the gas inside the gas storage device during the static stage. Then, through S2 and S3, the change of the state parameters of the gas inside the gas storage device is calculated. The gas mass flow rate of the gas storage device during the static stage is 0, and the transient operating parameters at each time step during the static duration are recorded. S4.3: The transient operating parameters at the end of the static stage are used as the initial conditions and boundary conditions for calculating the state parameters of the gas inside the gas storage device during the energy release stage. During the calculation process, the transient operating parameters of the gas storage device at each time step also synchronously affect the exhaust parameters at that transient; the end point of the energy release stage 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, the energy release duration of the first cycle is determined, and the transient operating parameters at each time step during the energy release stage are recorded. S4.4: Calculate the transient operating parameters at each time step of the static stage after the end of the energy release stage according to step (2), and use them as the initial conditions and boundary conditions for the next cycle. S4.5: Repeat steps S4.1-S4.4 to calculate the transient operating parameters of multiple cycles, record the operating parameters such as the energy storage duration, energy release duration, maximum temperature during the energy storage stage, minimum temperature during the energy storage stage, maximum temperature during the energy release stage, and minimum temperature during the energy release stage in each cycle. Use time series analysis to analyze the stability of each operating parameter to determine the stable cycle operating conditions.

10. An electronic device, characterized in that: Stores the method for determining the stable cycle operating conditions of the gas storage device according to any one of claims 1-9.

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