An economic operation system of a CAES unit after load rejection and a control method thereof

Abstract

This invention provides an economical operation system and control method for CAES (Compressed Air Storage) units after load shedding, belonging to the field of compressed air energy storage. The method first executes a load shedding process after the unit is disconnected from the grid, causing the speed to drop back to a preset value. Then, by acquiring energy consumption data for three strategies—continuous operation of the single-stage expander, intermittent control, and restart after shutdown—and combining the intersection of energy consumption curves, an energy consumption threshold is determined. Finally, based on the comparison between the unit's real-time energy consumption and the energy consumption threshold, the optimal operating strategy is dynamically selected. This method solves the problem of high air consumption during traditional continuous operation and avoids the drawback of long downtime and reconnection time, minimizing total energy consumption during the disconnection and reconnection period. Furthermore, the intermediate-stage expander in the system is equipped with an independent intake regulating valve and intake pipe, enabling control of the single-stage expander. The solution of this invention solves the problems of low operating efficiency and wasted air resources in existing technologies, improving the system's economy.

Description

Technical Field

[0001] This invention belongs to the field of compressed air energy storage technology, specifically relating to an economical operation system and control method for a CAES unit after load shedding. Background Technology

[0002] In today's power systems, with the widespread application of renewable energy sources such as wind and solar power, their intermittency and volatility pose significant challenges to the stable operation of the power grid. Large-scale physical energy storage technology is crucial for ensuring the reliable operation of the power grid and achieving efficient storage and conversion of electrical energy, and has become a key area of ​​research and development in the power sector.

[0003] Compressed air energy storage (CAES) systems, as an important large-scale physical energy storage technology, play an increasingly crucial role in power systems. They store electrical energy by converting it into the potential energy of high-pressure air, and release this potential energy to drive turbines for power generation when needed. This effectively enables peak shaving, frequency regulation, and reserve capacity support for the power grid, helping to enhance the power system's ability to cope with the characteristics of renewable energy.

[0004] During the energy release and power generation phase of a CAES system, generating units may encounter sudden load shedding conditions, i.e., disconnection from the grid. Traditional strategies primarily involve maintaining the unit at its rated speed for rapid reconnection or shutting down the unit to await the next grid connection command. However, these strategies have significant drawbacks. While maintaining rated speed allows for rapid reconnection, it continuously consumes a large amount of compressed air during load shedding. Direct shutdown and reconnection, while saving air resources, results in a lengthy restart and grid connection process. Furthermore, both strategies are static decisions, failing to dynamically select the optimal operating mode based on the actual disconnection situation, making it difficult to achieve optimal system efficiency and causing unnecessary waste of air resources. Summary of the Invention

[0005] In view of this, the present invention proposes an economical operation system and control method for CAES units after load shedding, aiming to solve the problem of low operating efficiency of existing CAES systems under load shedding conditions due to insufficient consideration of economic factors.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides an economical operation control method for a CAES unit after load shedding, comprising the following steps:

[0008] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0009] Based on preset speed values, energy consumption data of the unit under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous power operation strategy, intermittent control strategy and shutdown-and-start strategy.

[0010] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0011] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0012] Furthermore, energy consumption data of the unit under the single-stage expander continuous operation strategy is obtained, including:

[0013] Once the unit speed drops back to the first preset speed value, the single-stage expander is controlled to continue intake air in order to maintain stable unit speed.

[0014] The system calculates the compressed air mass consumption, system enthalpy drop, and plant power consumption during the preset disconnection time.

[0015] Based on the compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the single-stage expander continuous work strategy is calculated.

[0016] Furthermore, acquire the unit's energy consumption data under the intermittent control strategy, including:

[0017] Once the unit speed stabilizes at the second preset speed value, the intake of the single-stage expander is intermittently controlled to maintain the unit speed within the preset range; the second preset speed value is less than the first preset speed value, and the second preset speed value is the upper limit of the preset range;

[0018] Compressed air mass consumption, system enthalpy drop, and plant power consumption during the statistical intermittent control period;

[0019] Based on the compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the intermittent control strategy is calculated.

[0020] Furthermore, acquire the unit's energy consumption data under the post-shutdown restart strategy, including:

[0021] After the unit is disconnected from the load, the air intake is stopped to shut down the unit until the speed returns to zero. Then, the single-stage expander is restarted to the second preset speed value.

[0022] The statistics include the consumption of compressed air mass, system enthalpy drop, and plant power consumption during the commissioning process.

[0023] The total energy consumption of the computer group under the shutdown restart strategy is based on compressed air mass consumption, system enthalpy drop, and plant power consumption.

[0024] Furthermore, energy consumption thresholds include:

[0025] First energy consumption threshold and second energy consumption threshold;

[0026] The first energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the single-stage expander continuous power-on strategy and the shutdown-and-restart strategy.

[0027] The second energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the intermittent control strategy and the shutdown-to-start strategy.

[0028] Furthermore, the optimal operating strategy for the generating unit is dynamically selected, including:

[0029] When the grid demand unit reconnection time is less than the preset time threshold, the single-stage expander continuous work strategy is selected as the optimal operating strategy.

[0030] When the grid demand unit reconnection time is greater than or equal to the preset time threshold and the real-time energy consumption is less than or equal to the first energy consumption threshold, the intermittent control strategy is selected as the optimal operating strategy.

[0031] When the grid demand unit reconnection time is greater than or equal to the preset time threshold, and the real-time energy consumption is greater than the first energy consumption threshold and less than the second energy consumption threshold, the intermittent control strategy is selected as the optimal operating strategy.

[0032] When the grid demand unit reconnection time is greater than or equal to the preset time threshold and the real-time energy consumption is greater than or equal to the second energy consumption threshold, the shutdown-to-start strategy is selected as the optimal operating strategy.

[0033] Secondly, the present invention provides an economical operation system for CAES units after load shedding, comprising:

[0034] A multi-stage expander unit, including a multi-stage expander, wherein each intermediate stage expander in the multi-stage expander is equipped with an independent intake regulating valve and an intake pipe;

[0035] Speed ​​sensor, used to monitor the unit's speed in real time;

[0036] Compressed air flow sensor is used to monitor the quality of compressed air at the expander inlet;

[0037] Multi-stage valve groups are arranged one-to-one in the pipeline from the air storage tank to the multi-stage expander to control the on / off state and flow rate of compressed air.

[0038] The control system is electrically connected to the speed sensor, flow sensor, multi-stage valve group and independent intake regulating valve respectively, and executes the economic operation control method after the CAES unit sheds load as described in the first aspect, dynamically adjusting the operation strategy after the load shedding.

[0039] Thirdly, the present invention provides an economical operation control device for a CAES unit after load shedding, comprising:

[0040] The load shedding emergency speed control module is used to execute the load shedding process after the unit sheds load and disconnects from the grid until the unit speed drops back to the preset speed value;

[0041] The energy consumption data acquisition module is used to acquire the unit's energy consumption data under three operating strategies based on preset speed values. The three operating strategies include the single-stage expander continuous power operation strategy, the intermittent control strategy, and the shutdown-and-start strategy.

[0042] The energy consumption threshold calculation and determination module is used to draw energy consumption curves for three operating strategies based on energy consumption data, and to determine the energy consumption thresholds between different operating strategies based on the intersection points between the energy consumption curves.

[0043] The optimal operation strategy dynamic selection module is used to dynamically select the optimal operation strategy of the unit based on the comparison between the real-time energy consumption after the unit is disconnected from the grid and the energy consumption threshold, with the goal of minimizing the total energy consumption during the period from unit disconnection to reconnection.

[0044] Fourthly, the present invention provides a computer device, the device including a processor and a memory:

[0045] The memory is used to store computer programs and send the instructions of the computer programs to the processor;

[0046] The processor executes the following steps according to the instructions of the computer program:

[0047] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0048] Based on preset speed values, energy consumption data of the unit under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous power operation strategy, intermittent control strategy and shutdown-and-start strategy.

[0049] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0050] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0051] Fifthly, the present invention provides a computer-readable storage medium on which a computer program is stored, and when executed by a processor, the computer program performs the following steps:

[0052] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0053] Based on preset speed values, energy consumption data of the unit under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous power operation strategy, intermittent control strategy and shutdown-and-start strategy.

[0054] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0055] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0056] Sixthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0057] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0058] Based on preset speed values, energy consumption data of the unit under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous power operation strategy, intermittent control strategy and shutdown-and-start strategy.

[0059] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0060] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0061] In summary, this invention provides an economical operation system and control method for CAES units after load shedding. The method first executes a load shedding process after the unit is disconnected from the grid, causing the speed to drop back to a preset value, thus avoiding the blind approach of directly maintaining rated speed or directly shutting down in traditional strategies. Then, by acquiring energy consumption data from three operating strategies—continuous operation of the single-stage expander, intermittent control, and restart after shutdown—and combining the intersection of energy consumption curves, an energy consumption threshold is determined, breaking the limitations of traditional static decision-making and achieving accurate quantification of the energy consumption characteristics of different operating modes. Based on this, the optimal operating strategy is dynamically selected by comparing the unit's real-time energy consumption with the energy consumption threshold. This solves the problem of high gas consumption during traditional continuous operation and avoids the drawback of long downtime and reconnection time, minimizing total energy consumption during the disconnection and reconnection period. Furthermore, in this system, the intermediate-stage expander of the multi-stage expander unit is equipped with an independent intake regulating valve and intake pipeline, enabling control of the single-stage expander and providing hardware support for the control system to execute the aforementioned control method. Through the above-mentioned system and control method design, this invention solves the problems of low operating efficiency and waste of air resources in the prior art, and improves the economy of CAES system under load shedding conditions. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a schematic diagram of the structure of an economical operation system of a CAES unit after load shedding, provided in an embodiment of the present invention.

[0064] Figure 2 A flowchart illustrating an economic operation control method for a CAES unit after load shedding, provided in an embodiment of the present invention;

[0065] Figure 3 Typical energy consumption curves for three operating strategies provided in embodiments of the present invention;

[0066] Figure 4 An energy consumption curve of a 100MW unit after load shedding is provided as an example of the present invention;

[0067] Figure 5 A block diagram of an economic operation control device for a CAES unit after load shedding, provided in an embodiment of the present invention;

[0068] Figure 6 This is a block diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0069] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0070] The background technology of this invention will be further introduced below.

[0071] Compressed air energy storage (CAES), as one of the technologies for large-scale, long-term energy storage, has become a key supporting technology in new power systems for smoothing fluctuations in renewable energy output and ensuring the safe and stable operation of the power grid, thanks to its advantages such as large storage capacity, short construction period, and environmental friendliness. In the energy release and power generation phase of a CAES system, compressed air in a high-pressure storage tank is heated and then fed into a multi-stage expander unit to perform work, driving a generator to generate electricity and providing auxiliary services such as peak shaving, frequency regulation, and backup power to the grid. However, in actual operation, CAES units inevitably encounter sudden load shedding conditions: when a grid fault occurs, a line trips, or a sudden change in dispatch instructions, the electrical connection between the unit and the grid is suddenly disconnected (i.e., disconnected), and the generator instantly loses its external load. If not properly controlled, this can cause a sharp increase in unit speed, seriously threatening equipment safety.

[0072] For load shedding conditions, traditional CAES systems generally employ two static response strategies: The first is a continuous operation strategy maintaining rated speed, which involves controlling the expander's air intake to keep the unit running at rated speed under no-load conditions, allowing for rapid grid reconnection after grid restoration. While this strategy ensures rapid reconnection, it requires a continuous supply of high-pressure compressed air to the expander to maintain speed during load shedding, resulting in significant waste of compressed air resources and drastically reducing the overall economic efficiency of the system. The second strategy is a direct shutdown and reconnection strategy, which involves directly cutting off the expander's air intake after load shedding, gradually reducing the unit's speed to zero, and then restarting the unit and reconnecting after grid restoration. While this strategy avoids air waste during load shedding, it takes approximately 20 minutes for the unit to accelerate from shutdown to rated speed and reconnect, failing to meet the grid's demand for rapid standby. Furthermore, frequent start-ups and shutdowns increase equipment wear and shorten the unit's lifespan.

[0073] More importantly, both of the aforementioned traditional strategies are static decision-making modes, only able to choose one or the other when load shedding occurs. They cannot adaptively select the optimal operating mode based on the dynamic changes in the actual disconnection time of the unit and the grid reconnection demand. For short-term disconnection (e.g., within 10 minutes), choosing to shut down and reconnect would be counterproductive due to high start-up energy consumption and grid connection delays; for long-term disconnection (e.g., more than 1 hour), choosing continuous operation would result in serious waste of air resources. This static control logic makes it difficult for the CAES system to achieve optimal operating efficiency under load shedding conditions. It cannot balance the speed of reconnection with the economy of operation, and also causes unnecessary energy consumption, severely restricting the large-scale application and economic improvement of CAES technology.

[0074] Furthermore, existing CAES systems with multi-stage expanders mostly adopt a series intake structure, with each stage of expander sharing the intake pipe and valves. This makes it impossible to achieve independent intake control for a single-stage expander, further limiting the flexibility of operating strategies under load shedding conditions. It is impossible to reduce air consumption by intermittently introducing air into a single-stage expander, and it is also difficult to accurately control the unit speed. This further amplifies the shortcomings of traditional strategies and fails to fundamentally resolve the contradiction between economy and speed under load shedding conditions.

[0075] To address the technical shortcomings of existing CAES systems under load shedding conditions, particularly the high gas consumption during continuous operation, lengthy shutdown and reconnection times, inability to dynamically adapt to actual grid disconnection situations, low operating efficiency, and wasted air resources, this invention proposes an economical operation system and control method for CAES units after load shedding. By quantifying the energy consumption characteristics of three operating strategies and determining energy consumption thresholds, a dynamic decision-making mechanism based on real-time energy consumption and grid disconnection time is constructed. This enables adaptive optimal selection of operating strategies under load shedding conditions, balancing rapid reconnection with operational economy, fundamentally solving the pain points of existing technologies and improving the overall operating efficiency and economy of the CAES system. The following provides a detailed description of various embodiments of this invention.

[0076] This invention first provides an economical operation system for CAES units after load shedding, comprising:

[0077] A multi-stage expander unit includes multiple expanders, with each intermediate expander equipped with an independent intake regulating valve and intake pipe; a speed sensor for real-time monitoring of the unit's speed; a compressed air flow sensor for monitoring the quality of compressed air at the expander inlet; a multi-stage valve group, arranged one-to-one in the pipeline from the air tank to the multi-stage expander, for controlling the on / off state and flow rate of compressed air; and a control system electrically connected to the speed sensor, flow sensor, multi-stage valve group, and independent intake regulating valve, and executing the economic operation control method for CAES unit after load shedding as described in this invention, dynamically adjusting the operation strategy after load shedding.

[0078] In a CAES system, a multi-stage expander unit is a device used to convert the potential energy of compressed air into mechanical energy. It consists of multiple expanders, with intermediate-stage expanders (such as second- or third-stage expanders) being the non-initial and non-final-stage expanders, undertaking the main energy conversion task. The multi-stage expander unit is connected to the air storage tank via an intake pipe and to the heat storage tank and cold storage tank via heat exchange pipes, respectively.

[0079] The independent intake regulating valve and intake pipeline are intake control components and gas delivery pipelines specially configured for intermediate stage expanders. They can independently control the intake on / off and flow rate of the corresponding expander without interfering with the intake systems of other stage expanders.

[0080] The speed sensor is used to collect the speed data of the turbine unit (expander and generator linkage unit) in real time and provide speed feedback to the control system.

[0081] Compressed air flow sensors are used to monitor the mass flow rate of compressed air entering the expander inlet in real time, and to obtain air consumption data in order to calculate energy consumption.

[0082] Multistage valve groups are arranged on the pipeline from the air tank to each stage of the expander, including safety valves, speed regulating valves, power regulating valves, emergency exhaust valves, and squeegee regulating valves, to realize the on / off of compressed air, flow regulation, and pressure control.

[0083] The control system consists of a controller and related control modules. It can receive monitoring data from various sensors, output commands such as valve opening / closing and intake flow regulation, execute economic operation control methods (described in subsequent embodiments), and realize dynamic adjustment of the operation strategy.

[0084] For example, the structural design of the economic operation system in this embodiment is as follows: Figure 1 As shown, the system includes an air storage tank 1, which serves as a compressed air source. After being connected to a high-pressure main air valve 13 via a pipeline, the compressed air is split into two paths. One path connects to the first plate heat exchanger 8 via a rotary regulating valve 14 and a power regulating valve 15. The other path connects to a compressed air outlet branch main pipe 32, on which a compressed air outlet branch main pipe flow regulating valve 37 is installed. This compressed air outlet branch main pipe 32 further leads out to the secondary expander inlet branch (heating...) The first pipe 33 connects to the third-stage expander inlet branch (before heating) pipe 35; the second-stage expander inlet branch (before heating) pipe 33 passes through the second-stage expander branch inlet heat exchanger 40 and the second-stage expander inlet branch regulating valve (after heater) 34 before connecting to the second-stage expander 5; the third-stage expander inlet branch (before heating) pipe 35 passes through the third-stage expander branch inlet heat exchanger 41 and the third-stage expander inlet branch regulating valve (after heater) 36 before connecting to the third-stage expander 6.

[0085] The system is equipped with a multi-stage expander unit, specifically including a primary expander 4, a secondary expander 5, a tertiary expander 6, and a quaternary expander 7. The multi-stage expander unit is coaxially connected to a generator 31 to complete the power conversion. The power generated by the generator 31 is connected to the power grid through a grid-connected switch. The inlet and outlet regulating valves 16 and 17 of the first expander are respectively arranged in the inlet and outlet pipes of the primary expander 4. The inlet and outlet regulating valves 18 and 19 of the third expander are respectively arranged in the inlet and outlet pipes of the secondary expander 5. The inlet and outlet regulating valves 20 and 21 of the fifth expander and the sixth expander are respectively arranged in the inlet and outlet pipes of the tertiary expander 6. The inlet and outlet regulating valve 22 of the seventh expander is arranged in the inlet pipe of the quaternary expander 7. The outlet pipes of each expander are correspondingly equipped with a first exhaust valve 23, a second exhaust valve 24, and a third exhaust valve 25.

[0086] The first plate heat exchanger 8, the second plate heat exchanger 9, the third plate heat exchanger 10, and the fourth plate heat exchanger 11 are connected to each stage of the expander via inlet pipes. Each plate heat exchanger is connected to the heat pump 30 via its own branch pipe, and then to the heat storage tank 2. A heat exchange master valve 12 is installed at the inlet of the heat pump 30, and a first heat exchange valve 26, a second heat exchange valve 27, a third heat exchange valve 28, and a fourth heat exchange valve 29 are correspondingly installed on the branch pipes of each plate heat exchanger. Each plate heat exchanger is also connected to the cold storage tank 3 via its own other branch pipe. The inlet heat exchanger 40 of the second stage expander branch and the inlet heat exchanger 41 of the third stage expander branch are also connected to the heat exchange master valve 12 at the inlet of the heat pump 30 via the heat exchange regulating valve 38 of the second stage expander branch and the heat exchange regulating valve 39 of the third stage expander branch, respectively.

[0087] The system operates as follows: Under normal power generation conditions, the high-pressure compressed air output from the air storage tank 1 is regulated by pipelines and regulating valves before entering each stage of expanders to drive the generator 31 to generate electricity. Simultaneously, each plate heat exchanger, in coordination with heat exchange valves, heat pump 30, heat storage tank 2, and cold storage tank 3, completes air heat exchange and temperature regulation, ensuring efficient operation of the expander unit. The secondary and tertiary expanders, relying on independent intake valves and intake pipelines, can adjust the intake volume according to the power demand of the power grid to achieve rapid frequency regulation. When the unit experiences load shedding and disconnection from the grid, the system first calculates the plant's auxiliary power after disconnection. The system analyzes load characteristics and calculates the corresponding plant power consumption. It then flexibly controls the intake of the secondary or tertiary expander through an independent intake valve to maintain the unit speed. Simultaneously, it can switch between three control strategies according to operational needs: using a single-stage expander to continuously perform work to achieve rapid reconnection to the grid; intermittently opening and closing the independent air supply valve to precisely control the intake flow to optimize compressed air consumption; and directly shutting down the unit and restarting it after an instruction is issued. Finally, it dynamically selects the optimal shutdown and reconnection control strategy based on the actual disconnection time and the overall system energy consumption, taking into account both grid connection response speed and system operation economy.

[0088] Please see Figure 2 This invention also provides an economic operation control method for CAES units after load shedding, comprising the following steps:

[0089] S101: After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value.

[0090] Among them, load shedding and disconnection refers to the condition in which the CAES unit is disconnected from the grid due to an emergency during the energy release and power generation phase, and the unit no longer transmits power to the grid; the preset speed value refers to the target speed after the unit sheds load, when the speed exceeds the maximum value and falls back to the target speed where subsequent operation strategies can be adjusted.

[0091] Optionally, after a unit experiences load shedding and disconnection, the routine load shedding emergency procedure of the CAES system should be followed first to avoid damaging the equipment due to excessive unit speed, until the unit speed exceeds the maximum speed and gradually drops back to the preset speed value.

[0092] For example, after the unit is disconnected from the grid, the control system immediately initiates the emergency procedure, controls the relevant valves (such as exhaust valves) to exhaust gas appropriately to prevent the unit speed from rising suddenly, and monitors the speed data transmitted by the speed sensor until the unit speed exceeds the maximum speed and gradually decreases. When the speed drops back to 3090 r / min (preset speed value), the emergency exhaust operation stops.

[0093] S102: Based on the preset speed value, acquire the unit's energy consumption data under three operating strategies; the three operating strategies include the single-stage expander continuous power operation strategy, the intermittent control strategy, and the shutdown-and-start strategy.

[0094] Among them, the three operating strategies refer to the three grid recovery strategies that the CAES unit can adopt after load shedding: the single-stage expander continuous work strategy (using the single-stage expander to continuously work to maintain the speed, facilitating rapid grid reconnection), the intermittent control strategy (intermittently opening / closing the intake valve to optimize air consumption while maintaining unit operation), and the shutdown restart strategy (the unit is directly shut down and restarted for grid reconnection when needed); the energy consumption data refers to the relevant data such as compressed air mass consumption, system enthalpy drop, plant power consumption, and total energy consumption generated during the operation of the unit under different operating strategies.

[0095] Optionally, starting from a preset speed value, three operating strategies are initiated respectively. During the operation of each strategy, basic data such as compressed air mass consumption, system enthalpy drop, and plant power consumption are collected through monitoring components such as speed sensors and compressed air flow sensors. The running time of each strategy must meet the preset requirements to ensure that the energy consumption data is representative and can accurately reflect the energy consumption characteristics under that strategy.

[0096] For example, starting from a preset speed value, three operating strategies are initiated and energy consumption data are collected: When the single-stage expander continuous operation strategy is initiated, the intake regulating valve of the second or third stage expander is opened to maintain continuous air intake and operation of the single-stage expander for a duration of t1. The compressed air mass consumption during this period is counted by the compressed air flow sensor, the system enthalpy drop is calculated by the control system, and the plant power load characteristics are also counted. When the intermittent control strategy is initiated, after the unit speed stabilizes to the corresponding preset speed value, the intake regulating valve is intermittently opened / closed for a duration of t2 for each speed maintenance, and the total operating time is t3. Compressed air mass consumption, system enthalpy drop, and plant power consumption data are collected simultaneously. When the shutdown and restart strategy is initiated, all air intake is stopped to shut down the unit to 0 speed, and then the single-stage expander is restarted to the corresponding preset speed value. The compressed air mass consumption, system enthalpy drop, and plant power consumption data during the restart time t4 are counted. The three sets of data are recorded and archived for subsequent calculations.

[0097] S103: Plot the energy consumption curves for the three operating strategies based on the energy consumption data, and determine the energy consumption thresholds between different operating strategies based on the intersection points of the energy consumption curves.

[0098] Among them, the energy consumption curve refers to the curve of energy consumption changing over time under different operating strategies, plotted with operating time as the horizontal axis and total system energy consumption as the vertical axis; the energy consumption threshold refers to the energy consumption value corresponding to the intersection of the energy consumption curves of different operating strategies, which is the benchmark for judging the optimal operating strategy, and the energy consumption thresholds of different units are different.

[0099] Optionally, based on the basic energy consumption data of the three operating strategies collected, the total energy consumption of each strategy under different operating times is calculated. Then, with operating time as the horizontal axis and total energy consumption as the vertical axis, the energy consumption curves of the three strategies of continuous work, intermittent control, and restart after shutdown of the single-stage expander are plotted. Finally, the intersection points of the three curves are found, and the energy consumption value corresponding to each intersection point is the energy consumption threshold between different operating strategies, thus completing the determination of the energy consumption threshold.

[0100] S104: Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption during the period from unit disconnection to reconnection.

[0101] Among them, real-time energy consumption refers to the total energy consumption per unit time under the current operating state after the unit is disconnected from the grid, which is dynamically calculated by the control system based on the real-time collected air consumption and plant power consumption data; the optimal operating strategy refers to the operating strategy that can minimize the total energy consumption during the period from unit disconnection to reconnection under the current grid connection demand and energy consumption conditions, taking into account both economy and grid connection response speed.

[0102] Optionally, the system first obtains the grid reconnection time of the generating units to the grid and determines a preset time threshold. Then, the control system calculates the real-time energy consumption of the generating units. Next, the real-time energy consumption is compared with the determined energy consumption threshold. Based on the relationship between the grid reconnection time and the preset time threshold, the corresponding operating strategy is dynamically selected according to the goal of minimizing total energy consumption. Finally, the control system outputs control commands to execute the selected operating strategy, ensuring that the generating units can efficiently and quickly restore grid connection.

[0103] In this embodiment, by acquiring energy consumption data for three operating strategies of a single-stage expander—continuous operation, intermittent control, and restart after shutdown—and determining the energy consumption threshold by combining the intersection of energy consumption curves, the limitations of traditional static decision-making are broken, and accurate quantification of the energy consumption characteristics of different operating modes is achieved. Based on this, the optimal operating strategy is dynamically selected according to the comparison between the unit's real-time energy consumption and the energy consumption threshold. This not only solves the problem of high gas consumption during traditional continuous operation but also avoids the drawback of long downtime and reconnection time, thus minimizing the total energy consumption during the period from disconnection to reconnection.

[0104] In an exemplary embodiment, acquiring the unit's energy consumption data under a single-stage expander continuous operation strategy includes:

[0105] S201: When the unit speed drops back to the first preset speed value, control the single-stage expander to continue to intake air in order to maintain the unit speed stability.

[0106] Among them, the first preset speed value refers to the critical speed at which the speed falls back to the maximum value after the unit sheds the load, such as 3090 r / min; the single-stage expander continuous air intake refers to the control of the independent air intake regulating valve of a certain intermediate stage expander (second or third stage) to keep the compressed air continuously entering the expander, driving the expander to work continuously and maintaining the unit speed stable.

[0107] Optionally, after the unit is disconnected from the load, the unit speed is monitored. When the speed drops back to the first preset speed value, the control system issues a command to open the independent intake regulating valve of the designated single-stage expander, control the continuous intake of compressed air into the expander, so that the expander continues to do work and ensures that the unit speed is maintained within a stable range.

[0108] For example, after the unit is disconnected from the grid, the speed sensor monitors the speed change in real time. When the speed exceeds the maximum value and gradually drops back to 3090 r / min (the first preset speed value), the control system immediately outputs a control command to open the intake branch regulating valve of the secondary expander (or the intake branch regulating valve of the tertiary expander) and at the same time adjust the flow regulating valve of the compressed air outlet branch main pipe to control the continuous intake of compressed air into the secondary (or tertiary) expander, driving the expander to continuously do work. The intake flow is finely adjusted based on the speed data fed back by the speed sensor in real time to ensure that the unit speed is stable at about 3090 r / min and maintain this state until the preset disconnection time ends.

[0109] S202: Statistically calculate the compressed air mass consumption, system enthalpy drop, and plant power consumption within the preset disconnection time.

[0110] Among them, the preset disconnection time refers to the minimum operating time of a single-stage expander to continuously perform work, set to ensure the representativeness of energy consumption data, such as t1≥60min; compressed air mass consumption refers to the total mass of compressed air entering the single-stage expander within the preset disconnection time; system enthalpy drop refers to the change in enthalpy value per unit mass of air during the work performed by compressed air in the expander, reflecting the degree of air energy consumption; plant power consumption refers to the total power consumed by the unit's own plant power equipment (such as control system, pump body, etc.) within the preset disconnection time.

[0111] Optionally, under the condition that the single-stage expander is continuously working and the unit speed is stable, data statistics are started. The compressed air flow data is collected in real time through the compressed air flow sensor, and the compressed air mass consumption within the preset disconnection time is accumulated. The enthalpy drop under the stable operation state of the system is calculated through the control system. At the same time, the characteristics of the plant power load during this period are statistically analyzed, the plant power consumption is calculated, and the collection and statistics of the three types of basic energy consumption data are completed.

[0112] For example, the air mass consumption of a single-stage expander during the disconnection time t1 is calculated according to Equation 1. :

[0113] (1)

[0114] in, The instantaneous compressed air mass flow rate is t1≥60min.

[0115] Once the system reaches stability, calculate the enthalpy drop of the system under stable conditions. Meanwhile, the compressed air energy consumption is shown in equation (2):

[0116] (2)

[0117] in, Let t1 be the work done inside the expander.

[0118] Statistically analyze the plant's power load characteristics P(t) within time t1, and calculate the plant's power consumption according to formula (3):

[0119] (3)

[0120] in, The plant power consumption during the continuous operation of the single-stage expander.

[0121] S203: Based on the compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the single-stage expander continuous work strategy is calculated.

[0122] Total energy consumption refers to the total energy consumption of the unit within a preset disconnection time under the single-stage expander continuous work strategy, which is equal to the sum of compressed air energy consumption and plant power consumption during that period.

[0123] Optionally, three types of data are obtained: compressed air mass consumption, system enthalpy drop, and plant power consumption. Based on the preset energy consumption calculation formula, the compressed air energy consumption and plant power consumption are added together to obtain the total energy consumption of the unit under the single-stage expander continuous work strategy.

[0124] For example, the system energy consumption during time t1 is calculated as shown in equation (4):

[0125] (4)

[0126] in, This refers to the system's energy consumption.

[0127] This embodiment further proposes a method for acquiring energy consumption data for a single-stage expander continuous work strategy, which solves the problem in the prior art where the energy consumption data collection is not standardized and the calculation is inaccurate, leading to deviations in subsequent energy consumption comparison and threshold determination.

[0128] In an exemplary embodiment, acquiring the unit's energy consumption data under an intermittent control strategy includes:

[0129] S301: When the unit speed stabilizes at the second preset speed value, the intake of the single-stage expander is intermittently controlled to maintain the unit speed within the preset range; the second preset speed value is less than the first preset speed value, and the second preset speed value is the upper limit of the preset range.

[0130] The second preset speed value refers to the stable speed of the unit when the intermittent control strategy is started, such as 3000 r / min, and this speed is the upper limit of the preset speed range; the preset speed range refers to the speed range of the unit to maintain operation in the intermittent control strategy, such as 2900 r / min-3000 r / min; the intermittent control of the single-stage expander intake refers to controlling the intermittent entry of compressed air into the expander by periodically opening / closing the independent intake regulating valve of the single-stage expander, so that the unit speed fluctuates within the preset range and optimizes air consumption.

[0131] Optionally, after the unit speed stabilizes to the second preset speed value, the control system starts the intermittent control mode, intermittently opening / closing the independent intake regulating valve of the single-stage expander according to the preset cycle. When the speed drops to the lower limit of the preset range, the intake valve is opened to accelerate the speed; when the speed rises to the second preset speed value (upper limit of the range), the intake valve is closed. This cycle is repeated to maintain the unit speed within the preset range and reduce compressed air consumption.

[0132] For example, after the unit speed stabilizes at 3000 r / min (the second preset speed value), the control system closes the intake branch regulating valve of the secondary expander (or the intake branch regulating valve of the tertiary expander), intermittently cutting off the air supply to the expander, and the unit speed begins to gradually decrease; when the speed sensor detects that the speed has dropped to 2900 r / min (the lower limit of the preset range), the control system reopens the intake regulating valve, controls the compressed air to enter the single-stage expander to start, so that the speed rises back to 3000 r / min, maintains this speed for t2=5 minutes, and then closes the intake regulating valve again, repeating the above operation until the intermittent control cycle ends.

[0133] S302: Compressed air mass consumption, system enthalpy drop, and plant power consumption during the statistical intermittent control period.

[0134] The intermittent control cycle refers to the total running time of the intermittent control strategy, such as t3 > 60 min, and includes multiple "on-hold-off" intake operation cycles; the compressed air mass consumption within the intermittent control cycle refers to the total mass of compressed air consumed by all intake cycles during the entire intermittent control process; the system enthalpy drop and plant power consumption here are consistent with the definitions in the single-stage expander continuous work strategy, referring to the enthalpy drop of the system under steady-state conditions and the total power consumption of plant power equipment during the intermittent control period, respectively.

[0135] Optionally, during the execution of the intermittent control strategy, a data statistics program is simultaneously started to collect air flow data for each intake cycle through the compressed air flow sensor, and the compressed air mass consumption during the entire intermittent control cycle is accumulated; the system enthalpy drop during each intake spurt and speed stabilization phase is calculated by the control system, and the average value is taken as the system enthalpy drop during the intermittent control period; at the same time, the characteristics of the plant power load during the entire intermittent control cycle are statistically analyzed, the plant power consumption is calculated, and the statistics of the three types of basic energy consumption data are completed.

[0136] For example, air quality consumption during the execution of intermittent control strategies. for:

[0137] (5)

[0138] Where n represents the number of times intermittent control is completed.

[0139] The system reaches stability, and the enthalpy drop of the computing system is calculated. Meanwhile, the compressed air energy consumption is shown in equation (6):

[0140] (6)

[0141] in, The work done by compressed air in the expander during intermittent control.

[0142] Statistical Intermittent Control Period Plant Power Load Characteristics And calculate the plant's power consumption according to formula (7):

[0143] (7)

[0144] in, This refers to the electrical energy consumed by the plant during intermittent control periods.

[0145] S303: Based on compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the intermittent control strategy is calculated.

[0146] The total energy consumption under the intermittent control strategy refers to the total energy consumption of the unit during the entire intermittent control cycle. It is equal to the sum of compressed air energy consumption and plant power consumption during that cycle. It is used to measure the economic efficiency of the intermittent control strategy and is consistent with the total energy consumption calculation logic of the single-stage expander continuous work strategy.

[0147] Optionally, three types of basic data are obtained: compressed air mass consumption, system enthalpy drop, and plant power consumption. Based on the total energy consumption calculation logic consistent with the continuous work strategy of the single-stage expander, the compressed air energy consumption and the plant power consumption are added together to obtain the total energy consumption of the unit under the intermittent control strategy, thus completing the acquisition of energy consumption data for this strategy.

[0148] For example, the system energy consumption during the intermittent control period, i.e., time t3, is calculated as shown in equation (8):

[0149] (8)

[0150] in, This refers to the system energy consumption during intermittent control periods.

[0151] This embodiment proposes a method for acquiring energy consumption data under intermittent control strategy, which solves the problems of complex intake circulation, difficulty in energy consumption data acquisition, and non-standard calculation under intermittent control mode.

[0152] In an exemplary embodiment, obtaining the unit's energy consumption data under the shutdown-to-start strategy includes:

[0153] S401: After the unit is disconnected from the grid and the load is shed, stop the air intake to shut down the unit until the speed returns to zero, then restart the single-stage expander to the second preset speed value.

[0154] Among them, unit shutdown refers to the process after the unit is disconnected from the grid and all compressed air intake is stopped, so that the expander stops working and the unit speed gradually decreases to 0; restart refers to the process after the unit is shut down, by opening the intake valve to control the compressed air to enter the single-stage expander, drive the expander to rotate, and drive the unit speed to rise from 0 to the second preset speed value (3000r / min).

[0155] Optionally, after the unit is disconnected from the grid, the control system issues a command to close the intake regulating valves of all expanders and the intake valves in the multi-stage valve group, stopping the intake of compressed air and allowing the unit to shut down naturally until the speed drops to 0; then the start-up process is started, the intake regulating valve of the designated single-stage expander is opened, the compressed air is controlled to enter the expander to start up, and the unit speed is gradually increased until it stabilizes at the second preset speed value, thus completing the start-up process.

[0156] For example, after the unit is disconnected from the grid, the control system immediately closes the high-pressure main air valve, the secondary / tertiary expander inlet regulating valve, and the start-up regulating valve, stopping all compressed air intake. The unit loses its driving force, and the speed gradually decreases. The speed sensor monitors the speed change in real time until the speed drops to 0, completing the unit shutdown. Then, the start-up process is started, opening the start-up regulating valve and the tertiary expander inlet regulating valve to control the intake of compressed air into the tertiary expander, driving the expander to start up and gradually increasing the unit speed. By fine-tuning the intake flow, the speed is ensured to rise steadily until the speed stabilizes at 3000 r / min (the second preset speed value), and the total time t4 of the start-up process is recorded.

[0157] S402: Statistics on compressed air mass consumption, system enthalpy drop, and plant power consumption during the commissioning process.

[0158] Among them, the start-up process refers to the entire process of the unit increasing from 0 speed to the second preset speed value (3000 r / min); the compressed air mass consumption during the start-up process refers to the total mass of compressed air entering the single-stage expander during the start-up period; the system enthalpy drop refers to the enthalpy drop of compressed air doing work in the expander during the start-up process. Due to the more drastic temperature changes in the early stage of start-up, the system enthalpy drop is slightly greater than the system enthalpy drop of single-stage continuous work and intermittent control strategies; the plant power consumption refers to the total power consumed by plant power equipment (such as start-up auxiliary equipment and control system) during the start-up process.

[0159] Optionally, during the unit's start-up process, a data statistics program is simultaneously initiated. The compressed air flow sensor collects air flow data in real time during the start-up period, and the compressed air mass consumption during the start-up process is accumulated. The control system monitors the temperature and pressure changes at the inlet and outlet of the expander during the start-up process and calculates the system enthalpy drop during the start-up process. At the same time, the characteristics of the plant's power load within the start-up time t4 are statistically analyzed, and the plant's power consumption is calculated to complete the statistics of the three types of basic energy consumption data during the start-up process.

[0160] For example, the air consumption required to increase the expander speed from 0 to 3000 r / min for:

[0161] (9)

[0162] Once the system reaches stability, the enthalpy drop Δh2 of the system under steady-state conditions is calculated, and the compressed air energy consumption is obtained as shown in equation (10):

[0163] (10)

[0164] The characteristics of the plant's power load P(t) during time t4 are statistically analyzed, and the plant's power consumption is calculated according to formula (11):

[0165] (11)

[0166] in, This refers to the electrical energy consumed by the plant during the unit's start-up process.

[0167] S403: Total energy consumption of the computer group under the shutdown restart strategy, based on compressed air mass consumption, system enthalpy drop, and plant power consumption.

[0168] The total energy consumption under the shutdown-to-start strategy refers to the total energy consumption of the unit during the start-up process (from speed 0 to 3000 r / min), which is equal to the sum of compressed air energy consumption and plant power consumption during the start-up period. It is used to measure the economic efficiency of the strategy, especially the energy consumption characteristics during the start-up phase.

[0169] Optionally, three types of basic data are obtained: compressed air mass consumption, system enthalpy drop Δh2, and plant power consumption. Following the same total energy consumption calculation logic as the first two strategies, the compressed air energy consumption and plant power consumption are added together to obtain the total energy consumption of the unit under the shutdown-to-start strategy, thus completing the acquisition of energy consumption data for the three operating strategies.

[0170] For example, the system energy consumption during time t4 is calculated as shown in equation (12):

[0171] (12)

[0172] in, This refers to the system energy consumption during the unit's start-up process.

[0173] This embodiment proposes a method for acquiring energy consumption data for a post-shutdown restart strategy, which solves the problems of incomplete energy consumption data collection, special enthalpy drop calculation, and difficulty in data comparison during the post-shutdown restart process.

[0174] In one exemplary embodiment, the energy consumption threshold includes:

[0175] First energy consumption threshold and second energy consumption threshold;

[0176] The first energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the single-stage expander continuous power-on strategy and the shutdown-and-restart strategy.

[0177] The second energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the intermittent control strategy and the shutdown-to-start strategy.

[0178] The first energy consumption threshold is the critical value for judging the economic efficiency of the single-stage expander continuous power operation strategy and the shutdown-and-restart strategy. When the real-time energy consumption is lower than the threshold, the single-stage expander continuous power operation strategy is more economical; when the real-time energy consumption is higher than the threshold, the shutdown-and-restart strategy is more advantageous.

[0179] The second energy consumption threshold is the critical value for judging the economic efficiency of the intermittent control strategy and the shutdown-to-start strategy. When the real-time energy consumption is lower than this threshold, the intermittent control strategy is more economical; when the real-time energy consumption is higher than this threshold, the shutdown-to-start strategy is more advantageous.

[0180] Optionally, first, summarize the total energy consumption data of the three operating strategies and plot the energy consumption curve (time-energy consumption) for each strategy; then find the intersection point of the energy consumption curves of the single-stage expander continuous work strategy and the shutdown-after-run strategy. The energy consumption value corresponding to this intersection point is the first energy consumption threshold; then find the intersection point of the energy consumption curves of the intermittent control strategy and the shutdown-after-run strategy. The energy consumption value corresponding to this intersection point is the second energy consumption threshold.

[0181] For example, such as Figure 3 As shown, by comparing the three curves and their energy consumption, the intersection point of the energy consumption versus time curves can be obtained. The energy consumption corresponding to the intersection point is the energy consumption selection threshold for the three control strategies. In the continuous operation and intermittent control of the single-stage expander, the enthalpy drop during the expander's work process is basically the same. During the restart process, the compressed air mass flow rate consumption is relatively large, but after shutdown and restart, the unit is in a hot start-up state. The initial temperature change is not very drastic, and the enthalpy drop is slightly greater than the two processes mentioned above. Later, it maintains a stable 3000 r / min, and the enthalpy drop is equal to the two processes mentioned above.

[0182] The three typical intersection points represent the energy consumption threshold after load shedding. Different generating units have different energy consumption thresholds. The above process is for the initial confirmation of the energy consumption threshold of the generating unit itself.

[0183] In one exemplary embodiment, dynamically selecting the optimal operating strategy for the generator unit includes:

[0184] S501: When the grid demand unit reconnection time is less than the preset time threshold, the single-stage expander continuous work strategy is selected as the optimal operating strategy.

[0185] Among them, the preset time threshold refers to the basic time required for the CAES unit to restart from the shutdown state to a constant speed of 3000r / min, such as 20min; the grid demand unit reconnection time refers to the longest allowable time for the unit to go from load shedding to reconnecting to the grid as required by the grid dispatching command, which directly determines the priority of the operation strategy selection.

[0186] Optionally, first obtain the grid dispatch instruction to determine the grid-reconnection time of the unit; then compare the time with the preset time threshold (20 minutes). If the grid connection time is less than the preset time threshold, it means that the unit needs to quickly restore grid connection. At this time, the single-stage expander continuous work strategy that can achieve rapid grid connection is selected first to ensure timely grid connection.

[0187] For example, the preset time threshold is set to 20 minutes. The grid dispatch command requires the unit to reconnect to the grid within 20 minutes. At this time, the control system determines that it needs to quickly restore grid connection and immediately outputs a control command to open the intake regulating valve of the secondary expander and control the single-stage expander to continuously intake air to do work, maintaining the unit speed at about 3090 r / min. There is no need to consider short-term energy consumption, and priority is given to ensuring the grid connection speed, ensuring that the reconnection operation is completed within 20 minutes.

[0188] S502: When the grid demand unit reconnection time is greater than or equal to the preset time threshold and the real-time energy consumption is less than or equal to the first energy consumption threshold, the intermittent control strategy is selected as the optimal operating strategy.

[0189] Real-time energy consumption refers to the total energy consumption of the unit under the current operating state, which is dynamically calculated by the control system based on the real-time collected air consumption and plant power consumption data. If the real-time energy consumption is less than or equal to the first energy consumption threshold, it means that under the current state, the energy consumption of the single-stage expander continuous work or intermittent control strategy is lower than that of the shutdown and restart strategy. In combination with sufficient grid connection time, the intermittent control strategy with better energy consumption is selected first.

[0190] Optionally, when the grid connection time is greater than or equal to a preset time threshold (20 min), the total energy consumption of the real-time computer group of the control system is compared with the first energy consumption threshold (Q). thre.value1 Compare the results; if the real-time energy consumption is ≤ Q thre.value1 This indicates that the intermittent control strategy has better energy efficiency and can meet the grid connection preparation requirements, so the intermittent control strategy is selected as the optimal operating strategy.

[0191] For example, if the preset time threshold is 20 minutes and the grid connection time is 30 minutes (≥20 minutes), and the current total energy consumption of the unit is less than or equal to the first energy consumption threshold, the control system determines that the intermittent control strategy is more economical, starts the intermittent control mode, and intermittently opens / closes the intake regulating valve of the three-stage expander to maintain the speed in the range of 2900 r / min-3000 r / min, optimizes air consumption, and prepares for grid connection after 30 minutes.

[0192] S503: When the grid demand unit reconnection time is greater than or equal to the preset time threshold, and the real-time energy consumption is greater than the first energy consumption threshold and less than the second energy consumption threshold, the intermittent control strategy is selected as the optimal operating strategy.

[0193] If the real-time energy consumption is greater than the first energy consumption threshold and less than the second energy consumption threshold, it means that under the current state, the energy consumption of the intermittent control strategy is still lower than that of the shutdown-to-start strategy, but higher than that of the single-stage expander continuous work strategy. Given the sufficient grid connection time, the intermittent control strategy is still preferred to balance energy consumption and grid connection preparation efficiency.

[0194] Optionally, when the grid connection time is greater than or equal to a preset time threshold and the real-time energy consumption is between the first energy consumption threshold and the second energy consumption threshold, the control system determines that the intermittent control strategy is still the optimal choice, continues to execute the intermittent control mode, maintains the unit speed within the preset range, and continuously monitors the real-time energy consumption changes to ensure that the energy consumption does not exceed the second energy consumption threshold.

[0195] S504: When the grid demand unit reconnection time is greater than or equal to the preset time threshold and the real-time energy consumption is greater than or equal to the second energy consumption threshold, the shutdown restart strategy is selected as the optimal operating strategy.

[0196] Among them, if the real-time energy consumption is greater than or equal to the second energy consumption threshold, it means that under the current state, the energy consumption of the shutdown-after-start strategy is lower than that of the intermittent control and single-stage expander continuous work strategy. Combined with the condition of sufficient grid connection time, the shutdown-after-start strategy is selected to minimize the total energy consumption.

[0197] Optionally, when the grid connection time required by the power grid is greater than or equal to the preset time threshold and the real-time energy consumption is greater than or equal to the second energy consumption threshold, the control system determines that the restart strategy after shutdown is more economical, immediately stops the current operating mode, closes all intake valves, and shuts down the unit to 0 speed; when the power grid needs to be connected, the single-stage expander is restarted to 3000 r / min to complete the grid connection preparation and minimize the total energy consumption.

[0198] For example, if the preset time threshold is 20 minutes and the grid connection time is 60 minutes (≥20 minutes), and the current total energy consumption of the unit is greater than or equal to the second energy consumption threshold, the control system will immediately close the high-pressure main air valve and the intake regulating valve to stop the intake. The unit speed will gradually drop to 0 and enter the shutdown state. After the grid dispatching instruction is issued, the restart process will be started again to restart to 3000 r / min and complete the grid connection, minimizing the total energy consumption during the disconnection period.

[0199] This embodiment realizes the dynamic selection of the optimal operating strategy after load shedding, which solves the core technical problem that the existing CAES system adopts a static strategy after load shedding and cannot balance economy and grid connection response speed. By combining the comparison of grid connection time, real-time energy consumption and energy consumption threshold, the optimal strategy selection rules under different scenarios are clarified, and the total energy consumption during the period from unit disconnection to reconnection is minimized, thereby improving the economy and operational flexibility of the CAES system.

[0200] Please refer to it again. Figure 3Based on energy consumption thresholds, appropriate unit recovery strategies are selected according to the length of downtime. After the next load shedding, the method for restoring unit grid connection is determined based on statistical energy consumption. It is particularly important to note that the basic startup time for a CAES unit to reach a constant speed of 3000 r / min is approximately 20 minutes. Judging from the curve, if the grid requires the unit to be restored to grid connection within 20 minutes, then a single-stage expander intake to maintain speed should be prioritized; if the overall unit energy consumption Q... consume ≤Q thre.value1 If the recovery time exceeds 20 minutes, then intermittent control mode will be prioritized; if the unit energy consumption Q consume ≥Q thre.value,2 The machine can be shut down and then restarted according to the grid demand.

[0201] The present invention will now be described with reference to an example.

[0202] A 100MW CAES unit experienced a load shedding condition. Based on the implementation steps of the aforementioned embodiments, the following three scenarios were analyzed: single-stage expander operation, intermittent control, and restart after shutdown:

[0203] Single-stage expander power consumption: ;

[0204] Intermittent control: ;

[0205] After stopping, restart: ;

[0206] The energy consumption curves under three operating conditions are plotted as follows: Figure 4 As shown. Figure 4 In the middle, the energy consumption threshold Q thre.value1 =219168MJ, Q thre.value2 =219592.8MJ.

[0207] When the load shedding condition occurs, the unit reaches its maximum speed and then drops back down. Once the speed reaches 3090 r / min, the single-stage expander branch intake regulating valve is opened, and the following procedure is executed:

[0208] (1) The system begins to collect statistics on energy consumption after the unit sheds its load;

[0209] (2) If the load is shed due to a possible fault in the power grid or other reasons, the dispatcher shall issue an order for the unit to immediately reconnect to the grid. At this time, a single-stage expander shall be selected for air intake. After the unit recovers to 3000 r / min, it shall immediately reconnect to the grid and follow the dispatcher's load instructions for normal operation and adjustment.

[0210] (3) The unit does not receive an immediate reconnection instruction from the dispatcher, but needs to restore the unit to 3000 r / min standby (such as to provide rotational inertia support, etc.). In this case, determine the unit's energy consumption Q. consume When Q consumeWhen Q is ≤219168MJ, intermittent control mode is selected to maintain the expander operation, waiting for the next demand. consume When the gas supply is ≥219592.8MJ, the gas supply should be cut off at an appropriate time until the unit is shut down. Then, the start-up and grid connection operations should be performed according to the grid demand.

[0211] Based on the same inventive concept, this application also provides an economic operation control device for CAES units after load shedding, for implementing the above-mentioned economic operation control method for CAES units after load shedding. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in the embodiments of the economic operation control device for CAES units after load shedding provided below can be found in the limitations of the economic operation control method for CAES units after load shedding described above, and will not be repeated here.

[0212] Please see Figure 5 This invention also provides an economic operation control device for CAES units after load shedding, comprising:

[0213] The load shedding emergency speed control module is used to execute the load shedding process after the unit sheds load and disconnects from the grid until the unit speed drops back to the preset speed value;

[0214] The energy consumption data acquisition module is used to acquire unit energy consumption data under three operating strategies based on preset speed values. The three operating strategies include a single-stage expander continuous operation strategy, an intermittent control strategy, and a shutdown-and-start strategy.

[0215] The energy consumption threshold calculation and determination module is used to draw energy consumption curves for three operating strategies based on energy consumption data, and to determine the energy consumption thresholds between different operating strategies based on the intersection points between the energy consumption curves.

[0216] The optimal operation strategy dynamic selection module is used to dynamically select the optimal operation strategy of the unit based on the comparison between the real-time energy consumption after the unit is disconnected from the grid and the energy consumption threshold, with the goal of minimizing the total energy consumption during the period from unit disconnection to reconnection.

[0217] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0218] Reference Figure 6 This invention also provides a computer device, including: a memory and a processor, and a computer program stored in the memory. When the computer program is executed on the processor, it performs the following steps:

[0219] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0220] Based on preset speed values, the unit energy consumption data under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous work strategy, intermittent control strategy and shutdown-after-start strategy.

[0221] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0222] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0223] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. This computer device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 6 The examples of computer devices are merely examples and do not constitute a limitation on computer devices. They may include more or fewer components than shown in the illustration, or combinations of certain components, or different components. For example, they may also include input / output devices, network access devices, etc.

[0224] The processor referred to can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0225] In some embodiments, the memory may be an internal storage unit of the computer device, such as a hard drive or RAM. In other embodiments, the memory may be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory may include both internal and external storage units of the computer device. The memory is used to store the operating system, applications, boot loader, data, and other programs, such as the program code of the computer program. The memory can also be used to temporarily store data that has been output or will be output.

[0226] This invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0227] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0228] Based on preset speed values, the unit energy consumption data under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous work strategy, intermittent control strategy and shutdown-after-start strategy.

[0229] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0230] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0231] In this embodiment, if the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0232] This invention provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0233] After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value;

[0234] Based on preset speed values, the unit energy consumption data under three operating strategies are obtained respectively; the three operating strategies include single-stage expander continuous work strategy, intermittent control strategy and shutdown-after-start strategy.

[0235] Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and the energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves.

[0236] Based on the comparison between the real-time energy consumption and the energy consumption threshold after the unit is disconnected from the grid, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

[0237] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0238] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0239] In the embodiments disclosed in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0240] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for economical operation control of a CAES unit after load shedding, characterized in that, Includes the following steps: After the unit is disconnected from the grid, the load shedding process is executed until the unit speed drops back to the preset speed value; Based on the preset speed value, the energy consumption data of the unit under three operating strategies are obtained respectively; the three operating strategies include the single-stage expander continuous power operation strategy, the intermittent control strategy, and the shutdown and restart strategy. Based on the energy consumption data, energy consumption curves for three operating strategies are plotted, and energy consumption thresholds between different operating strategies are determined based on the intersection points of the energy consumption curves. Based on the comparison between the real-time energy consumption after the unit is disconnected from the grid and the energy consumption threshold, the optimal operating strategy of the unit is dynamically selected with the goal of minimizing the total energy consumption from the unit disconnection to reconnection.

2. The method for economical operation control of CAES unit after load shedding according to claim 1, characterized in that, Obtain the unit's energy consumption data under a single-stage expander continuous operation strategy, including: Once the unit speed drops back to the first preset speed value, the single-stage expander is controlled to continue intake air in order to maintain stable unit speed. The system calculates the compressed air mass consumption, system enthalpy drop, and plant power consumption during the preset disconnection time. Based on the compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the single-stage expander continuous work strategy is calculated.

3. The method for economical operation control of CAES units after load shedding according to claim 2, characterized in that, Acquire energy consumption data of the unit under the intermittent control strategy, including: Once the unit speed stabilizes at the second preset speed value, the intake of the single-stage expander is intermittently controlled to maintain the unit speed within the preset range; the second preset speed value is less than the first preset speed value, and the second preset speed value is the upper limit of the preset range; Compressed air mass consumption, system enthalpy drop, and plant power consumption during the statistical intermittent control period; Based on the compressed air mass consumption, system enthalpy drop, and plant power consumption, the total energy consumption of the unit under the intermittent control strategy is calculated.

4. The method for economical operation control of CAES unit after load shedding according to claim 3, characterized in that, Obtain the unit's energy consumption data under the post-shutdown restart strategy, including: After the unit is disconnected from the load, the air intake is stopped to shut down the unit until the speed returns to zero. Then, the single-stage expander is restarted to the second preset speed value. The statistics include the consumption of compressed air mass, system enthalpy drop, and plant power consumption during the commissioning process. The total energy consumption of the computer group under the shutdown restart strategy is based on the compressed air mass consumption, system enthalpy drop, and plant power consumption.

5. The method for economical operation control of CAES unit after load shedding according to claim 1, characterized in that, The energy consumption threshold includes: First energy consumption threshold and second energy consumption threshold; The first energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the single-stage expander continuous power-working strategy and the shutdown-and-restart strategy. The second energy consumption threshold is the energy consumption value corresponding to the intersection of the energy consumption curves of the intermittent control strategy and the shutdown-after-run strategy.

6. The method for economical operation control of a CAES unit after load shedding according to claim 5, characterized in that, Dynamically select the optimal operating strategy for the generating unit, including: If the grid demand unit reconnection time is less than a preset time threshold, then the single-stage expander continuous work strategy is selected as the optimal operating strategy. When the grid demand unit reconnection time is greater than or equal to the preset time threshold and the real-time energy consumption is less than or equal to the first energy consumption threshold, the intermittent control strategy is selected as the optimal operation strategy. When the grid demand unit reconnection time is greater than or equal to the preset time threshold, and the real-time energy consumption is greater than the first energy consumption threshold and less than the second energy consumption threshold, the intermittent control strategy is selected as the optimal operating strategy. When the grid demand unit reconnection time is greater than or equal to the preset time threshold, and the real-time energy consumption is greater than or equal to the second energy consumption threshold, the shutdown-to-start strategy is selected as the optimal operating strategy.

7. An economical operation system for a CAES unit after load shedding, characterized in that, include: A multi-stage expander unit includes a multi-stage expander, wherein each intermediate stage expander in the multi-stage expander is equipped with an independent intake regulating valve and an intake pipe. Speed ​​sensor, used to monitor the unit's speed in real time; Compressed air flow sensor is used to monitor the quality of compressed air at the expander inlet; A multi-stage valve group is arranged one-to-one in the pipeline from the air storage tank to the multi-stage expander to control the on / off state and flow rate of compressed air; The control system is electrically connected to the speed sensor, flow sensor, multi-stage valve group and independent intake regulating valve respectively, and executes the economic operation control method of CAES unit after load shedding as described in any one of claims 1-6, dynamically adjusting the operation strategy after load shedding.

8. An economical operation control device for a CAES unit after load shedding, characterized in that, include: The load shedding emergency speed control module is used to execute the load shedding process after the unit sheds load and disconnects from the grid until the unit speed drops back to the preset speed value; The energy consumption data acquisition module is used to acquire the unit's energy consumption data under three operating strategies based on the preset speed value; the three operating strategies include a single-stage expander continuous work strategy, an intermittent control strategy, and a shutdown-and-start strategy. The energy consumption threshold calculation and determination module is used to draw energy consumption curves for three operating strategies based on the energy consumption data, and to determine the energy consumption threshold between different operating strategies based on the intersection points between the energy consumption curves. The optimal operation strategy dynamic selection module is used to dynamically select the optimal operation strategy of the unit based on the comparison between the real-time energy consumption after the unit is disconnected from the grid and the energy consumption threshold, with the goal of minimizing the total energy consumption during the period from unit disconnection to reconnection.

9. A computer device, characterized in that, The device includes a processor and a memory: The memory is used to store computer programs and send the instructions of the computer programs to the processor; The processor executes, according to the instructions of the computer program, an economic operation control method for a CAES unit after load shedding as described in any one of claims 1-6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements an economic operation control method for a CAES unit after load shedding as described in any one of claims 1-6.

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