Operation control method of multistage air storage underwater compressed air energy storage system suitable for consumption photovoltaic power generation

Abstract

The invention discloses an operation control method of a multistage air storage underwater compressed air energy storage system suitable for consumption photovoltaic power generation. The system comprises at least two air storage chambers arranged at different water depths. The method comprises the following steps: monitoring photovoltaic output and the state of each gas storage chamber in real time; selecting a target mode from a plurality of preset energy storage modes based on the current photovoltaic output, the states of the gas storage chambers and the operation mode at the previous moment according to a preset power range, the gas storage capacity condition of each gas storage chamber, the switching complexity among different modes and the principle of fully absorbing the photovoltaic output; and generating an instruction according to the selected mode, and controlling the system to operate. According to the invention, the problems that the mode switching of the multistage gas storage system is complicated and the fluctuation photovoltaic output is difficult to efficiently match are solved, and the photovoltaic absorption capability of the system can be obviously improved. Meanwhile, the invention provides a photovoltaic installed capacity optimization design method based on the operation control method.

Description

Technical Field

[0001] This invention belongs to the field of compressed air energy storage technology, and specifically relates to an operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation. Background Technology

[0002] With the global energy structure transitioning towards green and low-carbon development, photovoltaics (PV) has garnered significant attention as an important form of renewable energy. However, the inherent intermittency and volatility of PV power generation severely impact the stable operation of the power grid, hindering its grid integration and consumption. Therefore, large-scale energy storage systems are needed to achieve peak shaving and valley filling of electricity. Compressed air energy storage (CAES) has become one of the most promising large-scale energy storage technologies due to its comprehensive advantages such as large scale, high output power, and long lifespan. Underwater CAES can utilize the hydrostatic properties of water to achieve constant pressure operation in the storage chamber, avoiding the sliding pressure operation of traditional constant-capacity systems and improving system performance through the presence of buffer air in the storage chamber. This makes it suitable for coordinated deployment with renewable energy sources such as PV and wind power.

[0003] Photovoltaic power output fluctuates over a wide range due to variations in solar irradiance. Existing underwater compressed air energy storage typically employs a single storage chamber and a fixed number of compression / expansion stages. The compressor operates near its rated operating point, resulting in a narrow high-efficiency operating range, insufficient system flexibility, and difficulty in matching fluctuating energy sources. While using multi-stage storage chambers can expand the system's operating range, it also introduces multiple operating modes. How to efficiently and stably switch between modes based on fluctuating photovoltaic output and changing storage conditions has become a key challenge restricting its practical application. Current technologies lack effective operational control strategies to address this problem. Summary of the Invention

[0004] To address the existing matching problem between underwater compressed air energy storage and photovoltaics, the present invention aims to provide an operation and control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation. This method can efficiently determine the optimal operating mode, efficiently absorb photovoltaic output within a wide power range, ensure stable system operation, and provide an optimization method for photovoltaic installed capacity during the system planning and design phase.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, the system comprising submerged compressed air energy storage systems arranged at different water depths. N One gas storage chamber ( N ≥2) and the piping and valve devices connecting the compressor unit, the gas storage chamber, and the expander unit; characterized in that the method includes the following real-time operation control cycle steps: Step 1 (Data Monitoring): Real-time monitoring of the output power of the photovoltaic power station PPV And obtain the gas storage status of each gas storage chamber in the system in real time. SOC 1. SOC 2, ... SOC N ; Step 2 (Mode Decision): Based on the current photovoltaic output P PV Gas storage status of each gas storage chamber SOC i (1≤ i ≤ N ), and the operating mode of the previous moment, from M Select a target operating mode from a set of predetermined energy storage modes; the energy storage mode corresponds to a line that compresses and stores air to a specific first... i The path of the gas storage chamber.

[0006] The core of the decision-making logic is: (1) to increase photovoltaic power output P PV The upper and lower limits of operating power set for each energy storage mode [ W ch,x,min , W ch,x,max ](1≤ x ≤ M (2) When photovoltaic output is compared; P PV When the power operation conditions of multiple energy storage modes are met at the same time, the mode that is the same as the operation mode at the previous moment shall be selected first; (3) If the selected mode cannot meet the gas storage conditions because the relevant gas storage chamber is full or empty, the alternative mode shall be activated according to the predetermined priority order; the priority order principle is: the mode with the fewest equipment operations has the highest priority; the mode that can avoid frequent switching of the system in adjacent cycles shall be selected first. (4) If the photovoltaic output P PV If the operating power range of a certain energy storage mode is met, but the gas storage conditions of that mode are not met, then an available energy storage mode with a lower operating power level can be started to partially absorb the photovoltaic output; (5) when the photovoltaic output P PV When the maximum allowable operating power of all energy storage modes of the system is exceeded, the system is controlled to operate at its maximum power level in the currently available highest power level mode to partially absorb the photovoltaic output; when the photovoltaic output... P PV When the operating power is lower than the minimum allowable operating power for all energy storage modes of the system, or when the gas storage conditions for all modes cannot be met, the system is controlled to enter a shutdown state.

[0007] Step 3 (Command Execution): Based on the selected target operating mode, generate control commands to control the valve assembly to switch and adjust the compressor's operating parameters so that the system operates in the target operating mode.

[0008] The upper and lower limits of the operating power for each energy storage mode [ W ch,x,min , W ch,x,max The determination is based on the variable operating characteristics of the compressor unit. The specific method is as follows: based on the isentropic efficiency characteristic curve of the compressor at different speeds and flow rates, the relationship between the air mass flow rate and the optimal isentropic efficiency within the safe operating range is obtained. Then, based on this relationship, the flow boundary for safe operation of the compressor, and the rated operating parameters of the system, the minimum and maximum allowable operating power of each energy storage mode is determined.

[0009] In addition, during the system planning and design phase, the optimal photovoltaic installed capacity for the multi-stage underwater compressed air energy storage system can be determined by the following methods: (1) establishing a photovoltaic output model based on historical sunlight data of the target water area; (2) establishing an operation simulation model of the energy storage system based on the operation control method; (3) using the maximization of photovoltaic energy storage ratio and gas storage device utilization rate as optimization objectives, and calculating the optimal photovoltaic installed capacity through the simulation model.

[0010] The gas storage state of the gas storage chamber SOC Defined as the ratio of the current gas storage mass to the rated gas storage mass; the photovoltaic-to-storage ratio is defined as the ratio of the photovoltaic power generation absorbed by the energy storage system to the total power generation in a day.

[0011] Compared with the prior art, the beneficial effects of the present invention are: (1) Fully utilize the operational potential of each energy storage mode, and at the same time, by introducing the previous operating mode and the gas storage state of the gas storage chamber as decision variables, the system can efficiently respond to the drastic fluctuations in photovoltaic output, significantly improve the photovoltaic energy storage ratio, and reduce the curtailment rate.

[0012] (2) The complexity of valve and compressor actions during the switching of different energy storage modes has been fully considered, which is conducive to the stable operation of the system.

[0013] (3) The capacity planning method provided can scientifically determine the photovoltaic installed capacity that best matches a specific multi-stage gas storage underwater compressed air energy storage system, thereby improving the economy and practicality of the entire photovoltaic energy storage system. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a multi-stage underwater compressed air energy storage system according to an embodiment of the present invention.

[0015] Figure 2Flowchart of the operation control logic of a multi-stage underwater compressed air energy storage system for absorbing photovoltaic power generation.

[0016] Figure 3 This is a schematic diagram illustrating the operating power range of different energy storage modes in embodiments of the present invention.

[0017] Figure 4 This is a schematic diagram illustrating the changes in daily energy storage capacity and photovoltaic energy storage ratio of the system with photovoltaic installed capacity in an embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram illustrating the changes in the gas storage status of the high- and low-pressure gas storage chambers with the photovoltaic installed capacity in an embodiment of the present invention.

[0019] Figure 6 This is an example of the energy storage process operation under actual sunlight conditions on the vernal equinox, according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 100. Energy storage process; 111. Filter; 121. First-stage compressor; 122. Second-stage compressor; 123. Third-stage compressor; 131. First-stage intercooler; 132. Second-stage intercooler; 133. Third-stage intercooler; 141. First-stage cooler; 142. Second-stage cooler; 143. Third-stage cooler; 150. Energy storage multi-way valve; 161. First energy storage gas pipeline; 162. Second energy storage gas pipeline; 170. Energy storage working fluid pump; 180. Low-temperature thermal storage working fluid distributor; 190. High-temperature thermal storage working fluid mixer; 200. Energy release process. 211. Silencer; 221. First-stage expander; 222. Second-stage expander; 223. Third-stage expander; 231. First-stage reheater; 232. Second-stage reheater; 233. Third-stage reheater; 250. Energy release multi-way valve; 261. First energy release gas pipeline; 262. Second energy release gas pipeline; 270. Energy release heat storage working fluid pump; 280. High-temperature heat storage working fluid distributor; 290. Low-temperature heat storage working fluid mixer; 300. Storage unit; 311. High-pressure gas storage chamber; 312. Low-pressure gas storage chamber; 321. High-temperature heat storage tank; 322. Low-temperature heat storage tank. Detailed Implementation

[0021] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0022] This invention provides a specific implementation of an operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in the example. This embodiment is for understanding the invention and does not limit the scope of protection.

[0023] This embodiment includes a high-pressure gas storage chamber 311 and a low-pressure gas storage chamber 312 (i.e. NTaking a system with =2 as an example, this system has three predetermined energy storage modes ( M =3), see system configuration (see 3). Figure 1 .

[0024] 1. System and Pattern Definition The multi-stage underwater compressed air energy storage system mainly includes compressor units (first-stage compressor 121, second-stage compressor 122, and third-stage compressor 123), expander units (first-stage expander 221, second-stage expander 222, and third-stage expander 223), high-pressure gas storage chambers 311 and 312 arranged at different water depths, and pipelines connecting the above components (such as first energy storage gas transmission pipeline 161, second energy storage gas transmission pipeline 162, first energy release gas transmission pipeline 261, and second energy release gas transmission pipeline 262), valves (such as energy storage multi-way valve 150 and energy release multi-way valve 250), and a heat storage system (high-temperature heat storage tank 321 and low-temperature heat storage tank 322). In this embodiment, the low-pressure gas storage chamber 311 is arranged at a depth of 114 meters underwater, and the high-pressure gas storage chamber 312 is arranged at a depth of 500 meters underwater. Both gas storage chambers use flexible gas storage devices, utilizing the static pressure characteristics of water to achieve constant pressure in the gas storage chambers during system operation. During energy storage, the clean electricity generated by the photovoltaic system drives an electric motor to power a compressor, compressing atmospheric air to a high-pressure state. This high-pressure air then enters an underwater constant-pressure / low-pressure storage chamber via an underwater energy storage pipeline. The heat generated during compression is recovered using cryogenic high-pressure water and stored in a high-temperature thermal storage tank 321. During energy release, the high-pressure air is released from the underwater storage chamber at a constant pressure. The stored high-temperature high-pressure water heats the high-pressure air before it enters the expander. The heated high-temperature high-pressure air drives the expander to perform work and powers a generator. The cooled high-pressure water returns to the cryogenic thermal storage tank 322.

[0025] The three predetermined energy storage modes are defined as follows: Energy Storage Mode 1: Ambient air is sequentially compressed by all three-stage compressors (121, 122, 123), cooled by intercoolers (131, 132, 133), and then stored in the high-pressure gas storage chamber 311 via the second energy storage gas pipeline 162. This mode corresponds to the highest energy storage power level, with a rated energy storage power of [missing information]. W ch,1 =117.4 MW, with an operational range of 80.0 MW to 144.0 MW. The gas storage status of high-pressure gas storage chamber 311 in this mode. SOC H It must be less than the upper limit. SOC H,max This refers to the gas storage situation corresponding to ①, ②, ③, ④, ⑤, and ⑥ in Table 2.

[0026] Energy Storage Mode 2: Ambient air is compressed only by the first two stages of compressors (121, 122), and then intermediately cooled by intercoolers (131, 132) and coolers (141, 142) before being stored in the low-pressure storage chamber 312 via the first energy storage gas pipeline 161. This mode corresponds to a medium energy storage power level, with a rated energy storage power of... W ch,2 =74.4 MW, with an operational range of 51.0 MW to 91.0 MW. The gas storage status of low-pressure gas storage chamber 312 in this mode. SOC L It must be less than the upper limit. SOC L,max This refers to the gas storage situation corresponding to ①, ②, ④, ⑤, ⑦, and ⑧ in Table 2.

[0027] Energy Storage Mode 3: Air is extracted from the low-pressure storage chamber 312, enters the third-stage compressor 123 through the first energy storage gas pipeline 161, and is compressed. The compressed air is cooled by the intercooler 133 and the cooler 143, and then enters the high-pressure storage chamber 311 through the second energy storage gas pipeline 162. This mode corresponds to the lowest energy storage power level, with a rated energy storage power of... W ch,3 =41.9 MW, with an operational range of 29.0 MW to 51.0 MW. The gas storage status of low-pressure gas storage chamber 312 in this mode. SOC L It must be greater than the lower limit SOC L,min And the gas storage state of the high-pressure gas storage chamber 311 SOC H Less than the upper limit SOC H,max This refers to the gas storage situation corresponding to ②, ③, ⑤, and ⑥ in Table 2.

[0028] During the energy release process, air flows out of the gas storage chamber at a rated flow rate, and the expander always operates under rated conditions. The following two energy release modes exist: Energy release mode 1: Air in the high-pressure gas storage chamber 311 overcomes the pressure loss of the second energy release gas transmission pipe 262 and the air column pressure inside the pipe, and then passes through the three-stage reheater (231, 232, 233) and the three-stage expansion (221, 222, 223) to perform work before being discharged into the atmosphere. This mode corresponds to the highest power generation level, with a rated power generation of [missing information]. W dch,1 =100.0 MW.

[0029] Energy release mode two: The air in the low-pressure gas storage chamber 312 overcomes the pressure loss of the first energy release gas transmission pipe 261 and the air column pressure inside the pipe, and then passes through two reheaters (232, 233) and two expansion stages (222, 223) to perform work before being discharged into the atmosphere. This mode corresponds to the lowest power generation level, with a rated power generation of [missing information]. W dch,2 =67.9 MW.

[0030] The rated power of each of the above energy storage and release modes is determined based on the rated operating parameters of the system; the upper and lower limits of the operating power of each energy storage mode are determined based on the variable operating characteristics of the compressor unit. The specific method is as follows: based on the isentropic efficiency characteristic curve of the compressor at different speeds and flow rates, the relationship between the air mass flow rate and the optimal isentropic efficiency within the safe operating range is obtained. Then, based on this relationship, the flow boundary for the safe operation of the compressor, and the rated operating parameters of the system in Table 1, the minimum and maximum allowable operating power of each energy storage mode is determined.

[0031] Table 1. Rated operating parameters of the multi-stage underwater compressed air energy storage system described in the embodiment.

[0032] Table 2. Comparison of gas storage status between low-pressure gas storage chamber 312 and high-pressure gas storage chamber 311 in the embodiments described.

[0033] 2. Implementation of Operation Control Methods See Figure 2 This is a logic diagram for the operation control of a multi-stage underwater compressed air energy storage system. Specifically, the operation control method described in this embodiment cyclically executes the following steps in each control cycle: Step 1 (Data Monitoring): Real-time monitoring of photovoltaic power plant output power P PV Simultaneously, the gas storage status of the high-pressure gas storage chamber 311 is obtained through flow acquisition devices installed at the inlet and outlet of the gas storage chamber. SOC H Low-pressure gas storage chamber 312 gas storage status SOC L .

[0034] Step 2 (Pattern Decision): During system operation, based on the currently monitored photovoltaic output power P PV High-pressure gas storage chamber 311 gas storage status SOC H Low-pressure gas storage chamber 312 gas storage status SOC LBased on the previous operating mode, a target operating mode is selected from the three energy storage modes and shutdown according to the following decision logic: (1) Photovoltaic power output P PV The upper and lower limits of the operating power set for the three energy storage modes [ W ch,x,min , W ch,x,max ]( x Compare (=1, 2, 3) to determine P PV The power range it falls into. Figure 3 The operating power range of the system in different energy storage modes of the embodiment is shown. There are a total of 7 cases depending on the photovoltaic output.

[0035] (2) When photovoltaic power output P PV When the power operation conditions of multiple energy storage modes are met simultaneously, the mode that is the same as the previous operation mode is selected first to reduce the number of equipment operations.

[0036] (3) If the above-mentioned preferred mode cannot meet the gas storage conditions because the relevant gas storage chamber is full or empty, other alternative modes that meet the power conditions shall be activated according to the predetermined priority order. The priority order principle is: the mode with the fewest equipment operations has the highest priority; the mode that can avoid frequent switching of the system in adjacent cycles shall be selected first.

[0037] (4) If photovoltaic power output P PV If the operating power range of a certain energy storage mode is met, but the gas storage conditions of that mode are not met, then an available energy storage mode with a lower operating power level can be activated to achieve partial absorption of photovoltaic power.

[0038] (5) When photovoltaic power output P PV When the maximum allowable operating power of all energy storage modes of the system is exceeded, the system is controlled to operate at its maximum power level in the currently available highest power level mode to partially absorb the photovoltaic output; when the photovoltaic output... P PV When the operating power is lower than the minimum allowable operating power for all energy storage modes of the system, or when the gas storage conditions for all modes cannot be met, the system is controlled to enter a shutdown state.

[0039] The following is combined with Figure 3 Tables 2 and 3 illustrate the system operation options under each energy storage scenario: Scenario I: When P PV < Wch,3,min This means that when the photovoltaic output power is less than the minimum operating power of the system energy storage process, the system enters a shutdown state. Situation II: When W ch,3,min ≤ P PV < W ch,2,min That is, the photovoltaic output power is only within the operating power range of energy storage mode three. If the gas storage status meets the gas storage conditions of energy storage mode three (i.e., conditions ②, ③, ⑤, and ⑥ in Table 2), the system will operate in energy storage mode three; otherwise, it will be in a shutdown state. Situation III: When W ch,2,min ≤ P PV < W ch,3,max That is, the photovoltaic output power is within the common operating power range of energy storage mode 3 and energy storage mode 2. At this time, it is necessary to select according to the system operating status at the previous moment: (1) If the operating status at the previous moment is shutdown or energy storage mode 3, the preferred order is energy storage mode 3, energy storage mode 2, shutdown; if the gas storage status meets the gas storage conditions of energy storage mode 3 (i.e., cases ②, ③, ⑤, and ⑥ in Table 2), the system will operate energy storage mode 3; if the gas storage status does not meet the gas storage conditions of energy storage mode 3, but meets the conditions of energy storage mode 2 (i.e., cases ①, ④, ⑦, and ⑧ in Table 2), the system will operate energy storage mode 2; if the gas storage conditions of energy storage mode 2 and 3 are not met (i.e., case ⑨ in Table 2), the system will be in shutdown state. (2) The operating state at the previous moment was either energy storage mode one or energy storage mode two, and the preferred order was energy storage mode two, energy storage mode three, and shutdown; if the gas storage state meets the gas storage conditions of energy storage mode two (i.e., cases ①, ②, ④, ⑤, ⑦, and ⑧ in Table 2), the system will operate in energy storage mode two; if the gas storage state does not meet the gas storage conditions of energy storage mode two, but meets the conditions of energy storage mode three (i.e., cases ③ and ⑥ in Table 2), the system will operate in energy storage mode three; if the gas storage conditions of energy storage mode two and three are not met (i.e., case ⑨ in Table 2), the system will be in shutdown state; Situation IV: When W ch,3,max ≤ P PV < W ch,1,min That is, the photovoltaic output power is only within the operating power range of energy storage mode 2. If the gas storage status meets the gas storage conditions of energy storage mode 2 (i.e., ①, ②, ④, ⑤, ⑦, ⑧ in Table 2), the system will operate in energy storage mode 2; otherwise, it will be in a shutdown state. Situation V: When W ch,1,min ≤ P PV < Wch,2,max That is, the photovoltaic output power is within the common operating power range of energy storage mode 2 and energy storage mode 1. At this time, it is necessary to select according to the system operating status at the previous moment: (1) If the operating status at the previous moment is shutdown or energy storage mode 2, the preferred order is energy storage mode 2, energy storage mode 1, shutdown; if the gas storage status meets the gas storage conditions of energy storage mode 2 (i.e., cases ①, ②, ④, ⑤, ⑦, ⑧ in Table 2), the system will operate energy storage mode 2; if the gas storage status does not meet the gas storage conditions of energy storage mode 2, but meets the conditions of energy storage mode 1 (i.e., cases ③, ⑥ in Table 2), the system will operate energy storage mode 1; if the gas storage conditions of energy storage mode 1 and 2 are not met (i.e., case ⑨ in Table 2), the system will be in shutdown state. (2) The operating state at the previous moment was either energy storage mode 1 or energy storage mode 3, and the preferred order was energy storage mode 1, energy storage mode 2, and shutdown. If the gas storage state meets the gas storage conditions of energy storage mode 1 (i.e., cases ①, ②, ③, ④, ⑤, and ⑥ in Table 2), the system will operate in energy storage mode 1. If the gas storage state does not meet the gas storage conditions of energy storage mode 1, but meets the conditions of energy storage mode 2 (i.e., cases ⑦ and ⑧ in Table 2), the system will operate in energy storage mode 2. If the gas storage conditions of energy storage mode 1 and mode 2 are not met (i.e., case ⑨ in Table 2), the system will be in shutdown state. Situation VI: When W ch,2,max ≤ P PV < W ch,1,max This means that the photovoltaic output power is only within the operating power range of energy storage mode one. If the gas storage status meets the gas storage conditions of energy storage mode one (i.e., cases ①, ②, ③, ④, ⑤, and ⑥ in Table 2), the system will operate in energy storage mode one. If the gas storage status does not meet the gas storage conditions of energy storage mode one, but meets the gas storage conditions of energy storage mode two (i.e., cases ⑦ and ⑧ in Table 2), the system will operate in energy storage mode two to consume part of the photovoltaic output. If the gas storage conditions of both energy storage modes one and two are not met (i.e., case ⑨ in Table 2), the system will be in a shutdown state. Situation VII: When W ch,1,max ≤ P PV If the photovoltaic output power is greater than the maximum operating power of the system during energy storage, then Energy Storage Mode 1 and Energy Storage Mode 2 are preferred to absorb part of the photovoltaic output. If the gas storage condition meets the gas storage conditions of Energy Storage Mode 1 (i.e., cases ①, ②, ③, ④, ⑤, and ⑥ in Table 2), the system will operate in Energy Storage Mode 1. If the gas storage condition does not meet the gas storage conditions of Energy Storage Mode 1, but meets the gas storage conditions of Energy Storage Mode 2 (i.e., cases ⑦ and ⑧ in Table 2), the system will operate in Energy Storage Mode 2 to absorb part of the photovoltaic output. If the gas storage conditions of both Energy Storage Mode 1 and 2 are not met (i.e., case ⑨ in Table 2), the system will be in a shutdown state. It should be noted that the gas storage condition for energy storage mode 3 is a sufficient but not necessary condition for energy storage mode 1. In cases V, VI, and VII, energy storage mode 1 is preferred when the gas storage conditions of both are met simultaneously. Therefore, there is no situation where energy storage mode 3 partially absorbs photovoltaic output. In case IV, although there may be times when the gas storage condition for energy storage mode 3 can be met, allowing energy storage mode 3 to absorb part of the photovoltaic output would easily cause frequent switching between mode 2 and mode 3, which is not conducive to the safe operation of the system. Therefore, this case is excluded.

[0040] Table 3 System Operation Mode Selection Table of the Embodiments

[0041] Step 3 (Instruction Execution) Based on the selected target operating mode, generate specific control instructions: Valve and compressor start / stop control: By controlling the energy storage multi-way valve 150 and the switches of the first, second, and third stage compressors (121, 122, 123), the airflow path is switched.

[0042] Compressor parameter adjustment: based on the current P PV And the operating mode, adjust the speed of the relevant compressor or the guide vane opening to make the input power of the compressor unit match the operating mode. P PV match.

[0043] 3. Application of capacity planning methods During the system planning and design phase, the optimal photovoltaic installed capacity for the multi-stage underwater compressed air energy storage system can be determined using the following methods: (1) Establishing a photovoltaic power output model: Based on the time series data of typical annual solar irradiance of the target water area and combined with the selected photovoltaic module parameters, a photovoltaic power station output model is established to simulate the time series output under different installed capacities. P PV ( t ).

[0044] (2) Establishing an operational simulation model for the energy storage system: Based on the real-time operation control method described above, an operational simulation model for a multi-stage underwater compressed air energy storage system is established, with the input being... P PV ( t The system displays the initial state of the gas storage chamber and outputs the daily stored energy, photovoltaic energy storage ratio, and the gas storage state of the gas storage chamber at the end of the energy storage period. The photovoltaic energy storage ratio is defined as the ratio of photovoltaic power generation absorbed by the energy storage system to the total power generation in a day.

[0045] (3) Determining the installed capacity: Using maximizing the photovoltaic energy storage ratio and the utilization rate of the gas storage device as optimization objectives, simulation calculations were performed under different preset photovoltaic installed capacities. The simulation results (such as...) were analyzed... Figure 4 , 5 As shown in the figure, the optimal photovoltaic installed capacity that achieves the best balance between the two objectives is found. For the system in this embodiment, the optimal photovoltaic installed capacity calculated by this method is approximately 260 MW.

[0046] Under the optimal photovoltaic installed capacity, the photovoltaic energy storage ratio of the system can reach 0.83 under typical annual irradiance conditions, which significantly reduces its luminous efficiency.

[0047] Taking the actual sunlight conditions on the vernal equinox in the waters near the Shandong Peninsula as an example, the multi-stage underwater compressed air energy storage system of the embodiment, when matched with an optimal photovoltaic installed capacity of 260 MW, operates in different modes at different times as follows: Figure 6 As shown, the system's total photovoltaic power consumption is 967.7 MWh, with a photovoltaic energy storage ratio of 0.72; the total output power of the system during the energy release process is 641.6 MWh, and the system round-trip efficiency is 66.3%. The system round-trip efficiency is defined as the ratio of the total output power of the energy release process to the total output power of the energy storage process.

Claims

1. An operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, the system comprising submerged compressed air energy storage systems arranged at different water depths. N One gas storage chamber ( N ≥2) and piping and valve devices connecting the compressor unit, the gas storage chamber, and the expander unit; characterized in that, The method includes the following real-time operation control loop steps: Step 1 (Data Monitoring): Real-time monitoring of the output power of the photovoltaic power station P PV And obtain the gas storage status of each gas storage chamber in the system in real time. SOC 1. SOC 2, ... SOC N ; Step 2 (Mode Decision): Based on the current photovoltaic output P PV Gas storage status of each gas storage chamber SOC i (1≤ i ≤ N ), and the operating mode of the previous moment, from M Select a target operating mode from the pre-defined energy storage modes; Step 3 (Command Execution): Based on the selected target operating mode, generate control commands to control the valve assembly to switch and adjust the compressor's operating parameters so that the system operates in the target operating mode.

2. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 1, is characterized in that... The core of the decision-making logic in step 2 is: (1) to increase photovoltaic power output P PV The upper and lower limits of operating power set for each energy storage mode [ W ch,x,min , W ch,x,max ](1≤ x ≤ M (2) When photovoltaic output is compared; P PV When the power operation conditions of multiple energy storage modes are met at the same time, the mode that is the same as the operation mode at the previous moment is selected first; (3) if the selected mode cannot meet the gas storage conditions because the relevant gas storage chamber is full or empty, the alternative mode is activated according to the predetermined priority order; (4) if the photovoltaic output P PV If the operating power range of a certain energy storage mode is met, but the gas storage conditions of that mode are not met, then an available energy storage mode with a lower operating power level can be started to partially absorb the photovoltaic output. (5) When the photovoltaic output P PV When the maximum allowable operating power of all energy storage modes of the system is exceeded, the system is controlled to operate at its maximum power level in the currently available highest power level mode to partially absorb the photovoltaic output; when the photovoltaic output... P PV When the operating power is lower than the minimum allowable operating power for all energy storage modes of the system, or when the gas storage conditions for all modes cannot be met, the system is controlled to enter a shutdown state.

3. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 2, is characterized in that... The upper and lower power operating limits of each energy storage mode [ W ch,x,min , W ch,x,max The determination is based on the variable operating characteristics of the compressor unit. The specific method is as follows: based on the isentropic efficiency characteristic curve of the compressor at different speeds and flow rates, the relationship between the air mass flow rate and the optimal isentropic efficiency within the safe operating range is obtained. Then, based on this relationship, the flow boundary for safe operation of the compressor, and the rated operating parameters of the system, the minimum and maximum allowable operating power of each energy storage mode is determined.

4. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 2, is characterized in that... The priority order of the predetermined energy storage modes is based on the following principles: (1) the mode with the fewest equipment operations has the highest priority; (2) the mode that can avoid frequent switching of the system in adjacent cycles is selected first.

5. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 1, is characterized in that... The energy storage mode corresponds to a process that compresses and stores air to a specific point. i The path of the gas storage chamber.

6. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 1, is characterized in that... In the system planning and design phase, the optimal photovoltaic installed capacity for the multi-stage underwater compressed air energy storage system can be determined by the following methods: (1) establishing a photovoltaic output model based on historical sunlight data of the target water area; (2) establishing an operation simulation model of the energy storage system based on the operation control method; (3) using the maximization of photovoltaic energy storage ratio and gas storage device utilization rate as optimization objectives, the optimal photovoltaic installed capacity is determined by calculation through the simulation model.

7. The operation control method for a multi-stage underwater compressed air energy storage system for absorbing photovoltaic power generation, as described in claim 6, is characterized in that... The historical illumination data includes time-series data of typical annual illumination intensity in the target water area.

8. The operation control method for a multi-stage underwater compressed air energy storage system for absorbing photovoltaic power generation, as described in claim 6, is characterized in that... The photovoltaic energy storage ratio is defined as the ratio of photovoltaic power generation absorbed by the energy storage system to the total power generation in a day.

9. The operation control method for a multi-stage underwater compressed air energy storage system suitable for absorbing photovoltaic power generation, as described in claim 1, is characterized in that... A preferred embodiment of the system includes a high-pressure gas storage chamber and a low-pressure gas storage chamber (i.e., N =2), the energy storage mode includes three energy storage modes (i.e. M =3): Mode 1: Ambient air is compressed by a compressor of all stages and then stored in the high-pressure storage chamber; Mode 2: Ambient air is compressed by a compressor with several stages and then stored in the low-pressure air storage chamber; Mode 3: The gas in the low-pressure gas storage chamber is extracted, compressed by a subsequent stage of compressors, and then stored in the high-pressure gas storage chamber.

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