Design method for external gas transmission pipeline of compressed air energy storage power station

Abstract

The invention discloses a compressed air energy storage power station external gas pipeline design method, and belongs to the technical field of compressed air energy storage power station design. Comprising the steps of inputting basic parameters of the compressed air energy storage power station; mass flow is distributed according to the volume of each gas storage; assumed pipeline parameters are input; calculating pressure loss and flow velocity from the compressed air energy storage power station to each gas storage in the gas storage process and the gas release process; calculating the total pressure loss of each gas storage in one gas storage-release cycle; judging whether the maximum flow speed is smaller than the maximum flow speed threshold value of the gas pipeline or not; judging whether the maximum pressure loss value is smaller than a pressure loss threshold value or not; judging whether the pressure loss range is smaller than a pressure loss range threshold value or not; and if the judging conditions are not met, the pipeline parameters are adjusted for judgment again, and the pipeline parameters meeting the judging conditions at the same time are output. While stable and efficient operation of the compressed air energy storage power station is guaranteed, the flow resistance loss difference generated by different underground gas storage gas pipelines is reduced, the economical efficiency of the compressed air energy storage power station is improved, and the service life of the compressed air energy storage power station is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressed air energy storage power station design, and particularly relates to a design method for the external gas transmission pipeline of a compressed air energy storage power station. Background Art

[0002] Increasing the power generation of renewable energy is an inevitable choice for building a new power system with renewable energy power generation as the main body. Due to the unstable power generation characteristics of renewable energy, there is a problem that some of the generated electricity cannot be grid-connected and is called abandoned electricity. How to reasonably utilize abandoned electricity and balance peak-valley electricity has become a problem that must be solved in the target technical path.

[0003] A compressed air energy storage system is a power energy storage system that can achieve large-capacity and long-time electrical energy storage. It compresses air through a compressor during the low-load period of the power grid, converts the excess electrical energy into pressure energy and thermal energy, and injects the compressed air into a gas storage reservoir for storage. This is the gas storage compression energy storage stage; and during the high-load period of the power grid, the high-pressure air in the gas storage reservoir is released, expands and does work through an expander, and drives a generator to generate electricity. This is the gas release expansion energy release stage.

[0004] The compressed air energy storage system relies on a large-capacity, low-leakage, stable and reliable gas storage device to store the compressed high-pressure air. Among them, natural salt caverns, as the gas storage reservoirs of compressed air energy storage power stations, have the advantages of large capacity, strong pressure-bearing capacity, high geological stability, strong airtightness, and low development cost, and have become the mainstream gas storage reservoir scheme for large-scale compressed air energy storage power stations in the current market. In the design process of the compressed air energy storage power station, for economic and compactness considerations, usually a single main pipe is used to connect multiple salt caverns at the same time. The distances of different salt caverns from the compressed air energy storage power station, their own volumes, buried depths are different, the different lengths and diameters of the gas transmission pipelines result in different frictional resistances along the way, and the different numbers of elbows and valves result in different local resistances, resulting in different pressure losses between each salt cavern during the gas storage / gas release process.

[0005] If the pressure losses of different salt caverns vary greatly, firstly, the overall efficiency of the system may be affected. Since the flow resistances of different salt caverns are different, it may lead to uneven flow rates in each salt cavern during gas storage and gas release. For example, the salt cavern with a small resistance may be filled or emptied faster, while the one with a large resistance is the opposite. This may cause some salt caverns to not be fully utilized, or it may take a longer time to balance the pressure, affecting the response speed and efficiency of the entire system. Secondly, considering the stability of the system, if the flow losses of some salt caverns are too large, pressure fluctuations may occur during gas storage or gas release processes. This will affect the pressure stability of the entire main pipe, and further affect the operation stability of the generator, and even affect the power supply quality of the power grid. Additionally, the control strategy will also become complex. If the flow characteristics of each salt cavern vary greatly, a more complex valve control and monitoring system may be required to regulate the flow rate and pressure of each branch, which will increase the complexity and cost of the system. Another aspect is the uneven utilization rate of salt caverns. The salt caverns with small flow losses may be overused, while those with large losses have a low utilization rate, resulting in faster wear and shorter lifespan of some salt caverns, while other salt caverns may be in an inefficient state for a long time, affecting the overall energy storage capacity and economy. Therefore, it is necessary to develop a design method for the external gas transmission pipeline of a compressed air energy storage power station for multiple underground gas storage caverns. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: uneven flow rates in each salt cavern during gas storage and gas release of a compressed air energy storage system will affect the stability of the generator. How to achieve the efficiency and service life of the energy storage system without increasing complex valve control.

[0007] To achieve the above object, the present invention provides a design method for the external gas transmission pipeline of a compressed air energy storage power station, including the following steps:

[0008] Step 1: Input the basic parameters of the gas storage cavern.

[0009] Step 2: Allocate the mass flow rate according to the basic parameters of the gas storage cavern.

[0010] Step 3: Input the assumed pipeline parameters.

[0011] Step 4: Calculate the pressure loss, flow velocity from the compressed air energy storage power station to each gas storage cavern during the gas storage process, and the pressure loss, flow velocity from the compressed air energy storage power station to each gas storage cavern during the gas release process according to the pipeline parameters, basic parameters of the gas storage cavern, and mass flow rate.

[0012] Step 5: Calculate the total pressure loss of each gas storage cavern in one gas storage - gas release cycle according to the pressure loss from the compressed air energy storage power station to each gas storage cavern during the gas storage process and the pressure loss from the compressed air energy storage power station to each gas storage cavern during the gas release process.

[0013] Step 6: Calculate the maximum flow velocity in the pipeline based on the flow velocities from the compressed air energy storage power station to each gas storage cavern during the gas storage process and the flow velocities from the compressed air energy storage power station to each gas storage cavern during the gas release process, obtain the casing strength of the gas transmission pipeline, salt rock geological parameters, pipe string vibration control, and calculate the maximum flow velocity threshold, and determine whether the maximum flow velocity is less than the maximum flow velocity threshold;

[0014] Step 7: Calculate the maximum pressure loss in the pipeline based on the total pressure loss, obtain the change in air static pressure at the inlet of the gas transmission pipeline during the gas storage - gas release cycle, and calculate the pressure loss threshold, and determine whether the maximum pressure loss is less than the pressure loss threshold;

[0015] Step 8: Calculate the pressure loss range based on the total pressure loss, calculate the pressure loss range threshold based on the maximum flow velocity threshold, and determine whether the pressure loss range is less than the pressure loss range threshold;

[0016] Step 9: If any of the judgment conditions in Step 6 to Step 8 is not met, adjust the pipeline parameters and execute the methods in Step 4 to Step 8 again;

[0017] Step 10: Output the pipeline parameters that simultaneously meet the judgment conditions in Step 6, Step 7, and Step 8.

[0018] The mass flow rate distribution method in Step 2 is as follows:

[0019]

[0020] In the formula, q n is the mass flow rate of the nth gas storage cavern, q m is the total mass flow rate of the air stored in the compressed air energy storage power station, V n is the volume of the nth gas storage cavern, and k is the number of gas storage caverns.

[0021] The pressure loss during the gas storage process in Step 4 takes into account the local resistance loss of the pipe fittings and is obtained using the calculation method of the frictional resistance. Its expression is:

[0022]

[0023] The pressure loss during the gas release process takes into account the local resistance loss of the pipe fittings and is obtained using the calculation method of the frictional resistance. Its expression is:

[0024]

[0025] Among them, △P 1n is the pressure loss of the nth gas storage cavern during the gas storage process, △P 2n is the pressure loss of the nth gas storage cavern during the gas release process, P c is the air static pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station, P n$P_{n}$ is the static air pressure at the shoe cover of the injection-production pipeline of the $n$-th gas storage reservoir. height $t$ is the static pressure difference of the gas column in the injection-production pipeline of the gas storage reservoir. c1 $t_{1}$ is the starting moment of the gas storage process. c2 $t_{2}$ is the ending moment of the gas storage process. e1 $t_{3}$ is the starting moment of the gas release process. e2 $t_{4}$ is the ending moment of the gas release process.

[0026] The above-mentioned calculation method of the frictional resistance is based on the Darcy-Weisbach formula.

[0027] The total pressure loss of each gas storage reservoir is the sum of the pressure loss during the gas storage process and the pressure loss during the gas release process.

[0028] The calculation method of the maximum pressure loss is as follows:

[0029]

[0030] In the formula, $\Delta P$ max is the maximum pressure loss, $\Delta P_{k}$ k is the pressure loss of the $k$-th gas storage reservoir.

[0031] The calculation method of the pressure loss threshold is as follows:

[0032]

[0033] In the formula, $\Delta P$ threshold is the pressure loss threshold, $P_{2}$ com is the static air pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the end of the gas storage process; $P_{3}$ tur is the static air pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the start of the gas release process.

[0034] The pressure loss range of the gas storage process or the gas release process is defined as:

[0035]

[0036] In the formula, $R$ P is the pressure loss range, $\Delta P_{\min}$ min is the minimum pressure loss of different gas storage reservoirs, and its calculation method is as follows:

[0037] .

[0038] The calculation method of the pressure loss range threshold is as follows:

[0039]

[0040] In the formula, $R$ Pthreshold is the pressure loss range threshold, $\rho$ c is the air density at the inlet of the gas transmission pipeline, $v$ thresholdis the maximum flow velocity threshold of the gas transmission pipeline.

[0041] The method for adjusting the pipeline parameters is as follows:

[0042] For the gas storage reservoir corresponding to the maximum pressure loss, increase the inner diameter of the gas transmission pipeline, the inner diameter and quantity of the injection-production pipeline, and reduce the flow loss of the corresponding salt cavern pipeline; for the gas storage reservoir corresponding to the minimum pressure loss, reduce the inner diameter of the gas transmission pipeline, the inner diameter and quantity of the injection-production pipeline, and reduce the investment and construction cost of the compressed air energy storage power station on the premise of ensuring the safe and efficient operation of the power station;

[0043] Optimize the inner diameter of the gas transmission pipeline and the inner diameter of the injection-production pipeline by using the sequential quadratic programming algorithm; optimize the quantity of the injection-production pipeline by using the mixed integer programming algorithm.

[0044] The present invention can obtain the optimal pipeline construction parameters for the energy storage system with multiple gas storage reservoirs, reduce the difference in flow resistance loss generated by the gas transmission pipelines of different underground gas storage reservoirs while ensuring the stable and efficient operation of the compressed air energy storage power station, improve the economy and service life of the compressed air energy storage power station, and reduce the investment and construction cost of the compressed air energy storage power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of a design method for the external gas transmission pipeline of a compressed air energy storage power station according to the present invention;

[0046] Figure 2 is a schematic structural diagram before the optimal design of a design method for the external gas transmission pipeline of a compressed air energy storage power station provided in Embodiment 1 of the present invention;

[0047] Figure 3 is a schematic structural diagram after the optimal design of a design method for the external gas transmission pipeline of a compressed air energy storage power station provided in Embodiment 1 of the present invention;

[0048] Figure 4 is a schematic structural diagram after the optimal design of a design method for the external gas transmission pipeline of a compressed air energy storage power station provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] Embodiment 1

[0051] As Figures 1-3 shown, a method for designing an inter-station gas transmission pipeline of a compressed air energy storage power station includes the following steps:

[0052] Step 101: Input the basic parameters of the gas storage reservoir, including: the number of gas storage reservoirs k, the volume V n of the nth gas storage reservoir, and the buried depth h n(i.e., the relative ground elevation at the nth injection-production pipeline shoe cover), the distance L between the nth underground gas storage and the compressed air energy storage power station n (i.e., the length of the gas transmission pipeline for the external output of the compressed air energy storage power station);

[0053] Reference Figure 2 , in this embodiment, a known compressed air energy storage power station includes three underground salt cavern gas storages, and the three underground salt cavern gas storages are distributed in the same direction of the compressed air energy storage power station, and they share a common gas transmission pipeline main pipe. Its basic parameters are shown in Table 1 below:

[0054] Table 1 Input parameters of each underground salt cavern gas storage

[0055]

[0056] Step 102: Allocate the initial mass flow rate q of each gas storage according to the basic parameters of the gas storage n ;

[0057] In this embodiment, during the process of storing and releasing compressed air in each gas storage, the distribution method of the mass flow rate q n is as follows:

[0058]

[0059] where q m is the total air mass flow rate during the gas storage process of the compressed air energy storage power station, which is determined by the energy storage capacity and energy storage duration of the compressed air energy storage power station, and V n represents the capacity of the nth gas storage. The total air mass flow rate q during the gas storage process of the compressed air energy storage power station n = 600 t / h. According to the calculation, the mass flow rates allocated to each underground salt cavern gas storage are shown in Table 2:

[0060] Table 2 Mass flow rates of each underground salt cavern gas storage

[0061]

[0062] Step 103: Input the assumed pipeline parameters, including: the inner diameter D of the gas transmission pipeline for each pipe section n , the inner diameter d of the injection-production pipeline of each underground gas storage n and the quantity m n ;

[0063] Conduct a preliminary design of the gas transmission pipeline parameters. The gas transmission pipeline for each pipe section uses a standard pipe with an inner diameter D n of 500 mm, and the injection-production pipelines of each underground gas storage use standard pipes with an inner diameter d n all of 273 mm. The initial quantity m of the injection-production pipes for each gas storage n is set according to the shape and capacity of the gas storage.

[0064] In this embodiment, the preliminary design results of the gas transmission pipeline parameters of each underground salt cavern gas storage are shown in Table 3 below:

[0065] Table 3 Preliminary design of gas transmission pipelines for each underground salt cavern gas storage

[0066]

[0067] Step 104: Calculate the pressure loss △P from the compressed air energy storage power station to each gas storage during the gas storage process, the flow velocity v 1n , and the pressure loss △P from the compressed air energy storage power station to each gas storage during the air release process 1n , the flow velocity v 2n ; 2n ;

[0068] According to the gas transmission pipeline parameters and the initial mass flow rate results allocated during the gas storage process, calculate the frictional pressure loss △p along the pipeline through the Darcy-Weisbach formula. Its expression is

[0069]

[0070] where λ is the Darcy friction factor, ρ is the air density in the pipeline, v is the average flow velocity of air in the gas transmission pipeline, D is the inner diameter of the gas transmission pipeline, and L is the length of the gas transmission pipeline.

[0071] In this embodiment, based on the above-mentioned preliminarily designed gas transmission pipeline and the initial mass flow rate allocated during the gas storage process, considering the local resistance losses of pipe fittings such as elbows and tees, the pressure loss △P from the compressed air energy storage power station to each gas storage during the gas storage process is obtained through the calculation method of frictional resistance 1n , which is defined as:

[0072]

[0073] where: P c is the static air pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station, P n is the static air pressure at the shoe cover of the injection-production pipeline of the nth salt cavern, t c1 is the starting moment of the gas storage process, t c2 is the ending moment of the gas storage process, P height is the static pressure difference of the gas column in the injection-production pipeline of the gas storage. The calculation formula for the static pressure difference P height of the gas column in the injection-production pipeline is:

[0074]

[0075] where: ρ c is the air density at the inlet of the gas transmission pipeline, h cis the relative ground elevation at the inlet of the gas transmission pipeline, ρ n is the air density at the shoe cover of the injection-production pipeline of the nth gas storage reservoir, h n is the relative ground elevation at the shoe cover of the nth injection-production pipeline.

[0076] Based on the initial mass flow rate of the gas transmission pipeline and the gas storage process distribution in the above preliminary design, considering the local resistance losses of pipe fittings such as elbows and tees, through the calculation method of frictional resistance along the way, the pressure loss △P from the compressed air energy storage power station to each gas storage reservoir during the air release process is obtained 2n , and its definition is:

[0077]

[0078] where t e1 is the starting moment of the air release process, t e2 is the ending moment of the air release process.

[0079] In this embodiment, the calculation method of frictional resistance along the way used is the Darcy-Weisbach formula.

[0080] Step 105: Calculate the total pressure loss △P of each gas storage reservoir for one storage-release cycle process according to the pressure loss from the compressed air energy storage power station to each gas storage reservoir during the gas storage process and the pressure loss from the compressed air energy storage power station to each gas storage reservoir during the air release process n ;

[0081] The total pressure loss △P of each underground salt cavern gas storage reservoir n is defined as the sum of the pressure loss during the gas storage process and the pressure loss during the air release process, and its expression is:

[0082]

[0083] In this embodiment, the total pressure loss values of each underground salt cavern gas storage reservoir are shown in Table 4 below,

[0084] Table 4 Total pressure loss and maximum flow velocity of each underground salt cavern gas storage reservoir

[0085]

[0086] Step 106: Calculate the maximum flow velocity in the pipeline according to the flow velocity from the compressed air energy storage power station to each gas storage reservoir during the gas storage process and the flow velocity from the compressed air energy storage power station to each gas storage reservoir during the air release process. Based on the casing strength of the gas transmission pipeline, salt rock geological parameters, and pipe string vibration control, calculate the maximum flow velocity threshold, and judge whether the maximum flow velocity v max is less than the maximum flow velocity threshold v threshold ;

[0087] In this embodiment, the maximum flow velocity threshold v threshold is the maximum flow velocity v based on the casing strength a, the maximum flow velocity v based on salt rock geological parameters b , the maximum flow velocity v based on the control of string vibration c jointly determine the comprehensive maximum allowable flow velocity value of the gas transmission pipeline, and its expression is: v threshold = min(v a , v b , v c ); the maximum flow velocity v max is the maximum value of the flow velocities v 1n and v 2n during the gas storage process and the gas release process, that is, the maximum flow velocities of the gas transmission pipeline and the injection-production pipeline of each underground salt cavern gas storage reservoir during the gas storage-release cycle under the allocated mass flow rate. The data shown in Table 4 are obtained through measurement and calculation. The maximum flow velocity of underground salt cavern gas storage reservoir 1 is 10.57 m / s, the maximum flow velocity of underground salt cavern gas storage reservoir 2 is 4.229 m / s, and the maximum flow velocity of underground salt cavern gas storage reservoir 3 is 3.174 m / s.

[0088] In summary, in this embodiment, the maximum flow velocity threshold v threshold = 18 m / s, and the maximum flow velocity v max = 10.57 m / s. By comparing the two, it can be seen that the conditions are met.

[0089] Step 107: Calculate the maximum pressure loss in the pipeline according to the total pressure loss, obtain the change in the static air pressure at the inlet of the gas transmission pipeline during the gas storage-release cycle, and calculate the pressure loss threshold, and judge whether the maximum pressure loss △P max of the gas storage reservoir is less than the pressure loss threshold △P threshold ;

[0090] △P max is the maximum pressure loss of different underground salt cavern gas storage reservoirs, and the calculation method is:

[0091]

[0092] The pressure loss threshold △P threshold is defined as the maximum total pressure loss value of the gas storage-release cycle that satisfies the stable operation of the compressed air energy storage power station, and the calculation method is:

[0093]

[0094] In the formula: P com is the static air pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the end of the compressed gas storage process; P tur is the static air pressure at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the beginning of the expansion gas release process.

[0095] In this embodiment, the relevant parameter values of the pressure loss threshold are shown in Table 5 below, and the calculated pressure loss threshold △P threshold= 250 kPa, the maximum pressure loss △P of the gas storage max = △P1 = 885.76 kPa. Comparing the two shows that the condition is not met.

[0096] Table 5 Pressure Loss Threshold

[0097]

[0098] Step 108: Calculate the pressure loss range according to the total pressure loss, calculate the pressure loss range threshold according to the maximum flow velocity threshold, and judge whether the pressure loss range R P is less than the pressure loss range threshold R Pthreshold ;

[0099] The pressure loss range R of a storage - release gas cycle P is defined as:

[0100]

[0101] In the formula, △P min is the minimum pressure loss in different underground gas storages, and the calculation method is:

[0102]

[0103] The pressure loss range threshold R Pthreshold The calculation method is:

[0104]

[0105] In the formula, ρ c is the air density at the inlet of the gas transmission pipeline, and v threshold is the maximum flow velocity threshold of the gas transmission pipeline.

[0106] In this embodiment, the pressure loss range , and the pressure loss range threshold . Comparing the two shows that the condition is not met.

[0107] Step 109: When any of the judgment conditions in Step 106, Step 107, and Step 108 is not met, adjust the inner diameter D of the gas transmission pipeline n , the inner diameter d of the injection - production pipeline n and the number m of injection - production pipelines n , and then re - execute the methods in Step 104 to Step 108.

[0108] Because the judgment conditions in Step 107 and 108 are not met, adjust the inner diameter D of the gas transmission pipeline n , the inner diameter d of the injection - production pipeline n and the number m of injection - production pipelines n , and the adjustment process follows the following principle: For the maximum pressure loss △P maxThe corresponding underground salt cavern gas storage needs to increase the inner diameter D of the gas transmission pipeline n , the inner diameter d of the injection-production pipeline n and the number m of injection-production pipelines n , so as to reduce the flow loss of the corresponding salt cavern pipeline; for the minimum pressure loss △P min The corresponding underground salt cavern gas storage needs to reduce the inner diameter D of the gas transmission pipeline n , the inner diameter d of the injection-production pipeline n and the number m of injection-production pipelines n , so as to reduce the investment and construction cost of the compressed air energy storage power station on the premise of ensuring the safe and efficient operation of the power station.

[0109] The sequential quadratic programming algorithm is used to optimize the inner diameter of the gas transmission pipeline and the inner diameter of the injection-production pipeline; the mixed integer programming algorithm is used to optimize the number of injection-production pipelines.

[0110] More specifically, in this embodiment, in the sequential quadratic programming (Sequential Quadratic Programming; SQP) algorithm, the maximum pressure loss, the maximum flow rate, and the minimum flow rate are used as the optimization boundaries, and the objective function is defined as the cost and the pressure loss. The input constraint functions include: inequality constraints (i.e., the pressure loss does not exceed the maximum pressure loss) and equality constraints (i.e., the pressure losses of each gas storage are balanced). Through the fmincon function, the SQP algorithm is used for optimization to obtain the optimized inner diameter of the gas transmission pipeline and the inner diameter of the injection-production pipeline. However, the actual inner diameter needs to be an integer, so there will be a slight difference in the final pressure loss.

[0111] For the mixed integer programming (Mixed Integer Programming; MIP) algorithm, first limit a maximum number of injection-production pipelines, combine the pipeline cost, and then introduce binary variables to determine whether each injection-production pipeline is used, that is, marked as "1" if used, and marked as "0" if not used.

[0112] Refer to Figure 3 As shown, in this embodiment, after multiple adjustments, when the gas transmission pipeline parameters of each underground salt cavern gas storage are as shown in Table 6 below:

[0113] Table 6 Optimal design of gas transmission pipelines for each underground salt cavern gas storage

[0114]

[0115] In this embodiment, the maximum number of injection-production pipelines is limited to 9, then the number of injection-production pipelines in Table 6 is recorded as (110, 100, 110), and the outer gas transmission pipeline of the compressed air energy storage power station after adjustment and optimization is judged. The calculation results are shown in Table 7:

[0116] Table 7 Calculation results of gas transmission pipelines for each underground salt cavern gas storage after optimal design

[0117]

[0118] After judgment, for the designed external gas transmission pipeline of the compressed air energy storage power station after adjustment and optimization, the maximum flow velocity of each underground salt cavern gas storage is 5.286 m / s, which meets the threshold judgment condition, and the maximum total pressure loss is 149.272 kPa, which also meets the threshold judgment condition. The range R P = 16.52 kPa also meets the threshold judgment condition.

[0119] Step 110: Output the pipeline design parameters that meet the judgment conditions in Step 106, Step 107, and Step 108.

[0120] Underground salt cavern gas storage 1: Inner diameter of the gas transmission pipeline is 500 mm, inner diameter of the injection and production pipeline is 273 mm, and the number of injection and production pipelines is 2; Underground salt cavern gas storage 2: Inner diameter of the gas transmission pipeline is 420 mm, inner diameter of the injection and production pipeline is 314 mm, and the number of injection and production pipelines is 1; Underground salt cavern gas storage 3: Inner diameter of the gas transmission pipeline is 380 mm, inner diameter of the injection and production pipeline is 273 mm, and the number of injection and production pipelines is 2.

[0121] A method for designing the gas transmission pipeline between compressed air energy storage power stations of the present invention can obtain optimal pipeline construction parameters for an energy storage system with multiple gas storage reservoirs. While ensuring the stable and efficient operation of the compressed air energy storage power station, it reduces the difference in flow resistance losses generated by the gas transmission pipelines of different underground gas storage reservoirs, improves the economy and lifespan of the compressed air energy storage power station, and reduces the investment and construction cost of the compressed air energy storage power station.

[0122] Embodiment 2

[0123] A method for designing the gas transmission pipeline between compressed air energy storage power stations includes the following steps:

[0124] Step 101: Input the basic parameters of the gas storage reservoir, including: input the number k of gas storage reservoirs, the volume V of each gas storage reservoir n , the buried depth h of each gas storage reservoir n , and the distance L between each gas storage reservoir and the compressed air energy storage power station n ;

[0125] In this embodiment, referring to the Figure 4 shown energy storage system includes three underground salt cavern gas storage reservoirs, which are distributed in different directions of the compressed air energy storage power station. Their basic parameters are as shown in Table 8 below:

[0126] Table 8 Input of parameters of each underground salt cavern gas storage reservoir

[0127]

[0128] Step 102: Allocate the mass flow rate q according to the basic parameters of the gas storage reservoirn ;

[0129] Step 103: The input assumed pipeline parameters include the inner diameter D of each section of the gas transmission pipeline n , the inner diameter d of each injection / production pipeline of the underground gas storage n and the corresponding quantity m n ;

[0130] Step 104: According to the pipeline parameters, the basic parameters of the gas storage and the mass flow data, calculate the pressure loss △P from the compressed air energy storage power station to each gas storage during the gas storage process 1n , the flow velocity v 1n and the pressure loss △P from the compressed air energy storage power station to each gas storage during the air release process 2n , the flow velocity v 2n ;

[0131] Step 105: According to the pressure loss from the compressed air energy storage power station to each gas storage during the gas storage process and the pressure loss from the compressed air energy storage power station to each gas storage during the air release process, calculate the total pressure loss △P of each gas storage in one gas storage - air release cycle n ;

[0132] Step 106: Calculate the maximum flow velocity in the pipeline according to the flow velocity from the compressed air energy storage power station to each gas storage during the gas storage process and the flow velocity from the compressed air energy storage power station to each gas storage during the air release process. Based on the casing strength of the gas transmission pipeline, the salt rock geological parameters, and the pipe string vibration control, calculate the maximum flow velocity threshold, and judge whether the maximum flow velocity v max is less than the maximum flow velocity threshold v threshold ;

[0133] Step 107: Calculate the maximum value of the pressure loss in the pipeline according to the total pressure loss, obtain the change in the static air pressure at the inlet of the gas transmission pipeline during the gas storage - air release cycle and calculate the pressure loss threshold, and judge whether the maximum pressure loss △P max is less than the pressure loss threshold △P threshold ;

[0134] Step 108: Calculate the pressure loss range according to the total pressure loss, calculate the pressure loss range threshold according to the maximum flow velocity threshold, and judge whether the pressure loss range R P is less than the pressure loss range threshold R Pthreshold ;

[0135] Step 109: If any of the judgment conditions in Steps 106 to 108 is not met, then adjust the inner diameter D of the gas transmission pipeline n , the diameter d of the injection / production pipeline n and the quantity m n , and execute the methods in Steps 104 to 108 above again;

[0136] Step 110: Output the pipeline design parameters that meet the judgment conditions in Step 106, Step 107, and Step 108.

[0137] In this embodiment, the relevant calculation steps are the same as those described in Embodiment 1, and will not be elaborated here.

[0138] Finally, the adjusted gas transmission pipeline design parameters are shown in Table 10 below.

[0139] Table 10 Optimal Design of Gas Transmission Pipelines for Each Underground Salt Cavern Gas Storage

[0140]

[0141] In summary, a method for designing a gas transmission pipeline between compressed air energy storage power stations according to the present invention can obtain optimal pipeline construction parameters for an energy storage system with multiple gas storage facilities. Even if multiple underground salt cavern gas storage facilities are distributed in different directions and cannot be connected by a single gas transmission main pipe, the above method can reduce the difference in flow resistance losses generated by gas transmission pipelines of different underground gas storage facilities while ensuring the stable and efficient operation of the compressed air energy storage power station, improve the economy and lifespan of the compressed air energy storage power station, and reduce the investment and construction costs of the compressed air energy storage power station.

[0142] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A design method for the external gas transmission pipeline of a compressed air energy storage power station, characterized in that Including the following steps: Step 1: Input the basic parameters of the gas storage reservoir; Step 2: Allocate the mass flow rate according to the basic parameters of the gas storage reservoir; Step 3: Input the assumed pipeline parameters; Step 4: According to the pipeline parameters, the basic parameters of the gas storage reservoir, and the mass flow rate, calculate the pressure loss, flow velocity from the compressed air energy storage power station to each gas storage reservoir during the gas storage process, and the pressure loss, flow velocity from the compressed air energy storage power station to each gas storage reservoir during the gas release process; Step 5: According to the pressure loss from the compressed air energy storage power station to each gas storage reservoir during the gas storage process and the pressure loss from the compressed air energy storage power station to each gas storage reservoir during the gas release process, calculate the total pressure loss of each gas storage reservoir in one gas storage - release cycle; Step 6: Calculate the maximum flow velocity in the pipeline according to the flow velocity from the compressed air energy storage power station to each gas storage reservoir during the gas storage process and the flow velocity from the compressed air energy storage power station to each gas storage reservoir during the gas release process, obtain the casing strength of the gas transmission pipeline, salt rock geological parameters, pipe string vibration control, and calculate the maximum flow velocity threshold, and determine whether the maximum flow velocity is less than the maximum flow velocity threshold; Step 7: Calculate the maximum pressure loss in the pipeline according to the total pressure loss, obtain the change in air static pressure at the inlet of the gas transmission pipeline during the gas storage - release cycle, and calculate the pressure loss threshold, and determine whether the maximum pressure loss is less than the pressure loss threshold; Step 8: Calculate the pressure loss range according to the total pressure loss, calculate the pressure loss range threshold according to the maximum flow velocity threshold, and determine whether the pressure loss range is less than the pressure loss range threshold; Step 9: If any of the judgment conditions in Steps 6 to 8 is not met, adjust the pipeline parameters and execute the methods in Steps 4 to 8 again; Step 10: Output the pipeline parameters that meet the judgment conditions in Steps 6, 7, and 8 simultaneously.

2. The design method of the external pipeline of a compressed air energy storage power station according to claim 1, characterized in that, The mass flow rate allocation method in Step 2 is: where q n is the mass flow rate of the nth gas storage reservoir, and q m is the total mass flow rate of the air stored in the compressed air energy storage power station, V n is the volume of the nth gas storage reservoir, and k is the number of gas storage reservoirs.

3. A method for designing an external pipeline of a compressed air energy storage power station according to claim 1, characterized in that, The pressure loss during the gas storage process in Step 4 takes into account the local resistance loss of the pipe fittings and is obtained using the method for calculating the frictional resistance, and its expression is: Among them, △P 1n is the pressure loss of the nth gas storage reservoir during the gas storage process, P c is the static pressure of the air at the inlet of the gas transmission pipeline of the compressed air energy storage power station, P n is the static pressure of the air at the shoe cover of the injection-production pipeline of the nth gas storage reservoir, P height is the static pressure difference of the gas column in the injection-production pipeline of the gas storage reservoir, t c1 is the starting moment of the gas storage process, t c2 is the ending moment of the gas storage process.

4. A design method for external pipelines of a compressed air energy storage power station according to claim 1, characterized in that, The pressure loss during the gas release process in Step 4 takes into account the local resistance loss of the pipe fittings and is obtained using the method for calculating the frictional resistance, and its expression is: Among them, △P 2n is the pressure loss of the nth gas storage reservoir during the gas release process, P c is the static air pressure at the inlet of the gas transmission pipeline of the compressed air energy storage power station, P n is the static air pressure at the shoe cover of the injection-production pipeline of the nth gas storage reservoir, P height is the static pressure difference of the gas column in the injection-production pipeline of the gas storage reservoir, t e1 is the starting moment of the gas release process, t e2 is the ending moment of the gas release process.

5. A design method for external pipelines of a compressed air energy storage power station according to claim 3 or 4, characterized in that, The method for calculating the frictional resistance is based on the Darcy - Weisbach formula.

6. A design method for external pipelines of a compressed air energy storage power station according to claim 1, characterized in that The total pressure loss of each gas storage reservoir is the sum of the pressure loss during the gas storage process and the pressure loss during the gas release process.

7. A design method for the external pipeline of a compressed air energy storage power station according to claim 1, characterized in that The calculation method for the maximum pressure loss is: where, △P max is the maximum pressure loss, and △P k is the pressure loss of the k-th gas storage reservoir The calculation method for the pressure loss threshold is: where △P threshold is the pressure loss threshold, and P com is the static pressure of the air at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the end of the gas storage process; P tur is the static pressure of the air at the inlet of the gas transmission pipeline outside the compressed air energy storage power station at the start of the air release process.

8. A method for designing an external pipeline of a compressed air energy storage power station according to claim 1, characterized in that, The definition of the pressure loss range during the gas storage process or the gas release process is: where R P is the differential pressure loss, and △P min is the minimum pressure loss of different gas storage reservoirs, and its calculation method is as follows: 。 9. The design method of the external pipeline of a compressed air energy storage power station according to claim 1, wherein The calculation method for the pressure loss range threshold is: where R Pthreshold is the threshold value of the pressure loss range, ρ c is the air density at the inlet of the gas transmission pipeline, v threshold is the threshold value of the maximum flow velocity of the gas transmission pipeline.

10. The design method of the external pipeline of a compressed air energy storage power station according to claim 1, wherein, The method for adjusting the pipeline parameters is: For the gas storage reservoir corresponding to the maximum pressure loss, increase the inner diameter of the gas transmission pipeline, the inner diameter and quantity of the injection - production pipelines; for the gas storage reservoir corresponding to the minimum pressure loss, decrease the inner diameter of the gas transmission pipeline, the inner diameter and quantity of the injection - production pipelines; Use the sequential quadratic programming algorithm to optimize the inner diameter of the gas transmission pipeline and the inner diameter of the injection - production pipelines; use the mixed - integer programming algorithm to optimize the quantity of the injection - production pipelines.

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