A method for controlling compressed air energy storage in parallel with an expansion power generation system

Abstract

The present invention relates to the field of power energy storage technology, and in particular to a method for controlling compressed air energy storage in parallel with an expansion power generation system. The method comprises the following steps: 1, determining the number of parallel gas storage devices and expansion power generation systems of the parallel compressed air energy storage power generation system, the number of expanders of each expansion power generation system, and the rated power generation power; 2, determining the target output curve of the compressed air energy storage system within the analysis period; 3, determining the generator output curve P of each expansion power generation system. Eτt ; Step 4, according to P Eτt , according to the pressure range of the gas storage device when each expansion power generation system is running, the opening and closing status of the corresponding gas storage device valve at each moment is judged to control the operation of the expansion power generation system; step 5, the maximum efficiency tracking algorithm is used to coordinate the control of gas flow and expansion ratio. This method can realize a variety of power generation combinations, with a wider operating range, higher compressed air utilization and energy storage efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy storage, and in particular to a method for controlling compressed air energy storage in parallel with an expansion power generation system. Background Art

[0002] Energy storage has become an effective way to solve the problem of new energy grid connection and consumption because of its ability to convert energy in time and space. Among them, the compressed air energy storage system has attracted much attention in recent years. When storing energy, it compresses the air under standard atmospheric pressure to a high-pressure state through a multi-stage compressor cascade and stores it in a gas storage device. When releasing energy, the high-pressure air drives the cascaded multi-stage expander to do work. The entire compressed air energy storage system has a specific rated power, and is matched with the corresponding compressor, expander stage and high-pressure gas pressure range.

[0003] In the current compressed air energy storage system, on the one hand, after the entire gas expansion process is completed, the gas pressure in the high-pressure gas storage chamber is still high and has not been fully utilized. Studies have shown that increasing the pressure range of the gas storage device is conducive to improving the energy storage efficiency of the energy storage device. Therefore, it is necessary to further improve the utilization rate of compressed gas in the gas storage device. On the other hand, as the main equipment participating in the peak and frequency regulation of the power grid, the output of the energy storage system will change greatly with the change of the operating state of the power system. When the output of the energy storage system deviates from the rated power generation, the power generation efficiency of the energy storage system decreases. Therefore, it is necessary to further increase the system power generation operating range to adapt to the inherent characteristics of large fluctuations in the output of new energy. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a compressed air energy storage control method for a parallel expansion power generation system, which can realize a variety of power generation combinations, have a wider operating range, and higher compressed air utilization and energy storage efficiency.

[0005] The present invention provides a control method for a compressed air energy storage system connected in parallel with an expansion power generation system. The method is used for a compressed air energy storage system connected in parallel with an expansion power generation system. The compressed air storage unit of the system includes a plurality of parallel gas storage devices. The expansion power generation unit includes a plurality of parallel expansion power generation systems with different rated power generation powers. The plurality of expansion power generation systems are respectively matched with different high-pressure gas pressure intervals. The method includes:

[0006] Step 1: According to the pressure operating range of the gas storage device, the maximum rated power generation that can be driven and the power demand of the energy storage system, the number of parallel gas storage devices and expansion power generation systems of the parallel compressed air energy storage power generation system, the number of expanders of each expansion power generation system and the rated power generation power are determined based on the cascade utilization of the gas storage device pressure;

[0007] Step 2, determining the target output curve of the compressed air energy storage system during the analysis period according to the wind and solar power output, power supply of the regional power grid and load power consumption, and power supply power curve;

[0008] Step 3: Construct an objective function by tracking the target output curve of the energy storage system and maximizing the generator efficiency of the expansion power generation system, set constraints, and determine the generator output curve P of each expansion power generation system. Eτt , where τ = 1, 2, …, N;

[0009] Step 4: According to the generator output curve P of each expansion power generation system Eτt , according to the pressure range of the gas storage device when each expansion power generation system is in operation, the switch status of the corresponding gas storage device valve at each moment is judged to control the operation of the expansion power generation system;

[0010] Step 5: Based on the output requirements of each expansion power generation system, a maximum efficiency tracking algorithm is used to coordinate the control of the gas flow rate and the expansion ratio so that the expander of the compressed air energy storage system can still operate near its optimal speed when the power demand changes.

[0011] Preferably, in step 3, the mathematical expression for tracking the target output curve of the energy storage system is:

[0012]

[0013] Where t is the current analysis period, T is the total analysis period, P Et is the total power generation of the compressed air energy storage system during the expansion process during period t, that is, the total output curve of the generators of each expansion power generation system, P Ct P is the power consumed by the compressed air energy storage system during the compression process during period t, At is the target power of the compressed air energy storage system during period t.

[0014] Preferably, the objective function for maximizing the generator efficiency of the expansion power generation system is:

[0015]

[0016] Where N is the total number of expansion power generation systems, τ is the τth expansion power generation system, P Eτt is the actual output of the τth expansion power generation system in period t, η Eτt is the generator operating efficiency of the τth expansion power generation system in period t, and its expression is:

[0017]

[0018] Where P Enτ is the rated power generation power of the τth expansion power generation system.

[0019] Preferably, in step 3, the constraint condition is:

[0020] The total output of each expansion power generation system in period t must meet the output demand of the energy storage system:

[0021] P E1t +P E2t +…+P ENt -P Et =0;

[0022] The compression and expansion processes of the same gas storage device cannot be carried out at the same time:

[0023] P Clt ·P Elt =0;

[0024] Where P Clt , P Elt They represent the power of the compression system and the expansion power generation system simultaneously connected to the gas storage device l at time t;

[0025] Compression power constraints of compressed air energy storage system:

[0026] P Cmin ≤P Ct ≤P Cmax ;

[0027] Compressed air energy storage system expansion power constraints:

[0028] P Eτmin ≤P Eτt ≤P Eτmax ;

[0029] Each expansion power generation system is connected to the gas storage device pressure p τt The following constraints are met:

[0030] p τmin ≤p τt ≤p τmax .

[0031] Preferably, step 4 comprises:

[0032] Step 401, clarifying the pressure range of the gas storage device corresponding to each expansion power generation system, and dividing them into pressure level 1, pressure level 2, ..., pressure level N in descending order;

[0033] Step 402: according to the generator output curve P of each expansion power generation system in step 3 Eτt , determine the expansion power generation system involved in operation during period t;

[0034] Step 403: Sort the expansion power generation systems operating in period t in descending order of power. Based on the measured pressure of the gas storage device, with the goal of meeting and as closely as possible approaching the pressure operating range of the expansion power generation system, sequentially select a matching gas storage device and control the operation of the expansion power generation system.

[0035] Preferably, the upper limit of the pressure corresponding to pressure level N for the gas storage device during the operation of the expansion power generation system < the lower limit of the pressure corresponding to pressure level N - 1 for the gas storage device during the operation of the expansion power generation system.

[0036] Preferably, the pressure corresponding to pressure level 1 is the gas storage device pressure p0 during the operation of the expansion power generation system, and the range of p0 is p2 ≤ p0 ≤ p1; the pressure corresponding to pressure level 2 is the gas storage device pressure p3 during the operation of the expansion power generation system, and the range of p3 is p5 ≤ p3 ≤ p4, where p4 < p2.

[0037] Preferably, the step 5 includes:

[0038] According to the required power P of each expansion power generation system Eτt , calculate the optimized expansion ratio π and optimized gas flow rate of the expander;

[0039] Obtain the optimized rotational speed ω according to the highest efficiency rotational speed optimization model * ;

[0040] Based on the optimized expansion ratio π and optimized gas flow rate, control the electronic power transformer so that when the power demand of the compressed air energy storage system changes, the expander can still operate near the optimized rotational speed ω * nearby.

[0041] Preferably, the compressed air energy storage system adjusts the operation and output of the parallel expansion power generation systems according to the actual operation demand of the power system to achieve different levels of power generation output. The different levels of power generation output include the output power of any one of the expansion power generation systems 1 - N operating alone, or the output power of a combination of any two or more expansion power generation systems operating together.

[0042] Preferably, the expansion power generation system includes at least a first expansion power generation system and a second expansion power generation system. The rated power generation of the first expansion power generation system is P1, and the rated power generation of the second expansion power generation system is P2, and P2 < P1. This system can achieve three different power generation combinations, namely the first expansion power generation system working alone, the second expansion power generation system working alone, and the first expansion power generation system and the second expansion power generation system working simultaneously. The power generation powers of the three power generation modes are P1, P2, and P1 + P2 respectively;

[0043] When the required power P of the system > P1, the first expansion power generation system and the second expansion power generation system work simultaneously;

[0044] When the expansion power generation system needs to switch from the first expansion power generation system to the second expansion power generation system due to dynamic changes in the power required by the system or due to insufficient compressed gas pressure; or when the expansion power generation system needs to switch from the second expansion power generation system to the first expansion power generation system due to dynamic changes in the power required by the energy storage system, it is preferred to use a gas storage device with a compressed air pressure in the range of p5 to p4 to drive the second expansion power generation system to generate electricity.

[0045] The beneficial effects of the present invention are:

[0046] 1. This system consists of a parallel gas storage device and a parallel expansion power generation unit that matches different high-pressure gas pressure ranges. The parallel expansion power generation units have different rated powers, which can realize a variety of power generation combinations, have a wider operating range, and higher compressed air utilization and energy storage efficiency.

[0047] 2. According to different system power requirements, by matching the expansion power generation system with a closer rated power, it is possible to better fit the demand for energy storage output of new energy, make the expansion power generation system closer to the rated operating state, and improve the system power generation efficiency. During the expansion power generation process, according to the gas storage pressure range required for the operation of each expansion power generation system, the residual pressure of the gas storage device is used in stages to improve the utilization efficiency of compressed air. In the selection of the generator of the expansion power generation system, the use of a direct-drive compressed air energy storage system can omit the high speed ratio gearbox (or use a small speed ratio gearbox), reduce the mechanical loss of the system, and has a simple structure and a long service life. In addition, the generator can change speed with the changes in gas storage volume and pressure, and has a wide operating range. While ensuring that the generator is in high-efficiency operation, the expander operates near the optimal speed, improving the power generation and operation efficiency of the compressed air energy storage system.

[0048] 3. The power generation system uses parallel high-pressure gas storage chambers and parallel expansion power generation systems with different rated power generation to achieve different levels of power generation output. By controlling the operation mode of the expansion power generation system, according to the actual operation needs of the power system, the parallel expansion power generation system is adjusted to achieve different levels of power generation output and expand the operation range of the compressed air energy storage system. While the compressed air energy storage system can achieve smooth wind power, photovoltaic and other outputs and peak-shaving and valley-filling functions, the expansion power generation system works as close to the rated operating conditions as possible, and the energy storage system has higher power generation efficiency. Under the condition of optimizing the compression link, the overall working efficiency of the compressed air energy storage system is improved by improving the energy storage efficiency and power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of system connection of the present invention;

[0050] Figure 2It is a schematic diagram of the control flow of the method of the present invention;

[0051] In the figure: 1, surplus electric energy; 2, compression system; 3, first expansion power generation system; 4, second expansion power generation system; 5, compressed air storage unit; 6, cold and hot storage unit; 10, motor; 11, first generator; 12, second generator; 21, first stage compressor; 22, second stage compressor; 31, first stage expander of first expansion power generation system; 32, second stage expander of first expansion power generation system; 33, first stage expander of second expansion power generation system; 41, first heat exchanger; 42, second Heat exchanger; 43, third heat exchanger; 44, fourth heat exchanger; 45, fifth heat exchanger; 51, first switch valve; 52, second switch valve; 53, third switch valve; 54, fourth switch valve; 55, fifth switch valve; 56, sixth switch valve; 57, seventh switch valve; 58, eighth switch valve; 59, ninth switch valve; 61, first throttle valve; 62, second throttle valve; 63, third throttle valve; 64, fourth throttle valve; 65, fifth throttle valve; 66, sixth throttle valve; 67, seventh throttle valve. DETAILED DESCRIPTION

[0052] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0053] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0054] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0055] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0056] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0057] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0058] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0059] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0060] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0061] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways. "Multiple" means "two or more".

[0062] Embodiment 1

[0063] Figure 1 Shows a preferred embodiment of the present application ( Figure 1 The structure diagram of a compressed air energy storage system in parallel with an expansion power generation system provided in the first embodiment of the present application is shown. For the sake of convenience, only the parts related to this embodiment are shown, which are described in detail as follows:

[0064] A compressed air energy storage system in parallel with an expansion power generation system of the present invention comprises a compression system, a compressed air storage unit 5, an expansion power generation unit and a cold and heat storage unit 6, wherein the compressed air storage unit 5 comprises a plurality of gas storage devices in parallel, and the expansion power generation unit comprises a plurality of expansion power generation systems in parallel with different rated power generation powers, wherein the plurality of expansion power generation systems are respectively matched with different high-pressure gas pressure intervals and have different operating power intervals, and the number of the gas storage devices is not less than the number of the expansion power generation systems, and the cold and heat storage unit 6 comprises a heat storage device and a cold storage device, wherein the input end of the compression system is connected to surplus electric energy 1, and the output end of the compression system is connected to the compressed air storage unit 5, and the heat generated during the compression process is stored in the heat storage device, and the compressed air storage unit 5 is connected to the input end of the expansion power generation system, and in each expansion power generation system, the high-pressure gas input to each expander is first heated by a heat exchanger and then connected to the inlet of the expander, and the medium after heat exchange is stored in the cold storage device.

[0065] A plurality of gas storage devices connected in parallel are connected to expansion power generation systems of different power generation levels (the number of gas storage devices is not less than the number of expansion power generation systems). The high-pressure air at the inlet of the expansion power generation system is heated by the heat in the heat storage device, driving the expander to do work, and at the same time storing the heat exchange medium after heat exchange in the cold storage device; the expander is connected to the generator, and the expander shaft rotates at high speed, driving the generator to generate electricity.

[0066] In this system, the compressed air storage unit consists of multiple parallel high-pressure gas storage devices. According to the original rated power generation of the compressed air energy storage system and the remaining pressure of the gas storage device after the expansion process, the lower limit value of the gas storage device pressure is determined by comprehensively considering the compression efficiency and the overall system efficiency. An expansion power generation system is added, and the rated power of the added power generation system is less than the original system's rated power generation to make full use of the remaining gas in the gas storage device. The resulting expansion power generation unit consists of a multi-stage or single-stage expander with different rated power generations connected to a generator.

[0067] This power generation system utilizes parallel high-pressure gas storage chambers and parallel expansion power generation systems with different rated power generations. By controlling the operation mode of the expansion power generation system and according to the actual operation requirements of the power system, the operation and output of the parallel expansion power generation system are adjusted to achieve different levels of power generation output, expanding the operation range of the compressed air energy storage system. This enables the compressed air energy storage system to smooth the output of wind power, photovoltaic power, etc., perform peak shaving and valley filling functions, while the expansion power generation system works as close as possible to the rated operating condition.

[0068] In this embodiment, the gas storage system is composed of 2 parallel gas storage devices, and the expansion part is composed of 2 parallel expansion power generation systems with different power generations. The expansion power generation system 1 has two-stage expansion, and the expansion power generation system 2 has single-stage expansion. This embodiment is only a special case of the system. In this system, the compression system can be multi-stage compression, the gas storage system can be composed of multiple parallel gas storage devices, the expansion part can be composed of multiple parallel expansion power generation systems, and the number of expansion stages in each expansion power generation system is determined according to needs. The parallel gas storage devices analyzed in this embodiment can always meet the normal operation of the expansion power generation system 1 and the expansion power generation system 2, without considering the extreme situation where the remaining pressure of the gas storage device cannot drive the expansion power generation system.

[0069] The gas storage system in this embodiment is composed of 2 parallel gas storage devices, and the expansion part is composed of 2 parallel expansion power generation systems with different rated power generations. The first expansion power generation system 3 has two-stage expansion, and the second expansion power generation system 4 has single-stage expansion. The rated power generation of the first expansion power generation system 3 is P1, and the rated power generation of the second expansion power generation system 4 is P2, and P2 < P1. This system can achieve three different power generation combinations, namely the first expansion power generation system 3 works alone, the second expansion power generation system 4 works alone, and the first expansion power generation system 3 and the second expansion power generation system 4 work simultaneously, with 3 rated operating power points, namely P1, P2, and P1 + P2.

[0070] In one embodiment, each gas storage device in the compressed air storage unit 5 is simultaneously connected to each expansion power generation system. The parallel gas storage devices store compressed air in sequence until the air pressure in the gas storage device reaches the set value. The inlet of each gas storage device controls the air intake of the gas storage device through a switch valve, and the air intake flow is controlled through a throttle valve. The outlet of each gas storage device controls the air outlet of the gas storage device through a switch valve, and the air outlet flow is controlled through a throttle valve. Each parallel gas storage device is connected to the expander of the expansion power generation system with different power generation levels. The inlet of each expansion power generation system controls the air intake of each expansion power generation system through a switch valve; the inlet of the heat exchanger of each expansion power generation system controls the flow of the heat source of the heat storage device through a switch valve. The heat exchange medium flow of the heat exchanger is adjusted by the throttle valve to control the inlet and exhaust temperature of each stage of the expander.

[0071] In one embodiment, the compression system 2 includes an electric motor 10, a first-stage compressor 21, a second-stage compressor 22, a first heat exchanger 41, and a second heat exchanger 42, wherein the electric motor 10, the first-stage compressor 21, and the second-stage compressor 22 are connected in series in sequence. The gas outlet of the first-stage compressor 21 is connected to the high-temperature gas inlet side of the first heat exchanger 41, and the high-temperature gas is cooled by the heat exchanger and connected to the inlet of the second-stage compressor 22 from the low-temperature gas outlet side of the first heat exchanger 41, and the gas outlet of the second-stage compressor 22 is connected to the high-temperature gas inlet side of the second heat exchanger 42, and the high-temperature gas is cooled by the heat exchanger and connected to the compressed air storage unit 5 from the low-temperature gas outlet side of the second heat exchanger 42, and the cold storage device is connected to the inlet side of the low-temperature heat exchange medium of the first heat exchanger 41 and the second heat exchanger 42 respectively, and the low-temperature heat exchange medium is connected to the heat storage device from the high-temperature heat exchange medium outlet side of the heat exchanger after heat exchange by the heat exchanger, so as to store the heat generated after the heat exchange.

[0072] Surplus electric energy (including surplus grid electric energy, abandoned wind power, abandoned photovoltaic power and other new energy power generation) supplies power to the motor 10, and the motor 10 drives the first-stage compressor 21 to compress air. The outlet gas of the first-stage compressor 21 is cooled by the first heat exchanger 41 and then output to the second-stage compressor 22 for further compression, and the compression heat is stored in the heat storage device. The outlet air of the second-stage compressor 22 is cooled by the second heat exchanger 42 and then stored in the gas storage device in the compressed air storage unit 5 in sequence. The connectivity and intake flow of the gas storage device 1 are controlled by the first switch valve 51 and the first throttle valve 61, and the connectivity and intake flow of the gas storage device 2 are controlled by the second switch valve 52 and the second throttle valve 62, and the compression heat is stored in the heat storage device.

[0073] In one embodiment, a heat exchanger is provided in front of each stage of the expander of the expansion power generation system, and the output end of the compressed air storage unit 5 is connected to the low-temperature gas inlet side of the heat exchanger in front of the expander. After the low-temperature gas is heated by the heat exchanger, the high-temperature gas outlet side of the heat exchanger is connected to the inlet of the expander.

[0074] The heat storage device is connected to the high-temperature heat exchange medium inlet side of the heat exchanger of the expansion power generation unit through the switch valve and the throttle valve respectively. After the high-temperature heat exchange medium is heat exchanged by the heat exchanger, it is connected to the cold storage device through the low-temperature heat exchange medium outlet side of the heat exchanger. The switch valve controls the communication between the heat storage device and the heat exchanger, and the throttle valve adjusts the heat exchange medium flow of the heat exchanger to control the inlet and exhaust temperature of each stage of the expander.

[0075] In one embodiment, the second expansion power generation system 4 comprises a fifth heat exchanger 45, a first-stage expander 33 of the second expansion power generation system, and a second generator 12 connected in sequence;

[0076] In one embodiment, the first expansion power generation system 3 includes a third heat exchanger 43, a first-stage expander 31 of the first expansion power generation system, a fourth heat exchanger 44, a second-stage expander 32 of the first expansion power generation system, and a first generator 11 connected in sequence;

[0077] In one embodiment, the output end of the heat storage device is connected to the high-temperature heat exchange medium input end of the third heat exchanger 43 through the fifth throttle valve 65 and the fifth switch valve 55; connected to the high-temperature heat exchange medium input end of the fourth heat exchanger 44 through the sixth throttle valve 66 and the sixth switch valve 56; connected to the high-temperature heat exchange medium input end of the fifth heat exchanger 45 through the seventh throttle valve 67 and the ninth switch valve 59; the low-temperature heat exchange medium output ends of the third heat exchanger 43, the fourth heat exchanger 44, and the fifth heat exchanger 45 are connected to the input end of the cold storage device.

[0078] Embodiment 2

[0079] like Figure 2 As shown, a control method of a compressed air energy storage system in parallel with an expansion power generation system of the present invention comprises:

[0080] Step 1: According to the pressure operating range of the gas storage device, the maximum rated power generation that can be driven and the power demand of the energy storage system, the number of parallel gas storage devices and expansion power generation systems of the parallel compressed air energy storage power generation system, the number of expanders and the rated power generation of each expansion power generation system are determined based on the cascade utilization of the gas storage device pressure; the number of parallel gas storage devices and expansion power generation systems of the parallel compressed air energy storage power generation system, and the rated power of each expansion power generation system can be determined based on the energy storage capacity demand of the area where the compressed air energy storage system is located, the efficiency of the compression link and the overall efficiency of the system, and the gas storage device operating pressure range is determined based on the cascade utilization of the residual pressure of the gas storage device. The number of parallel gas storage devices is greater than or equal to the number of expansion power generation systems.

[0081] Step 2: Determine the target output curve of the compressed air energy storage system during the analysis period based on the wind and solar power output, power supply of the regional power grid and load power supply, and power supply power curve; the output curve of the compressed air energy storage system can be determined according to existing methods, and the power supply and power consumption curve of the power system can be determined through power prediction, and the target output curve of the energy storage system can be determined with the goal of achieving smooth wind power, photovoltaic output, peak shaving and valley filling functions of the energy storage system.

[0082] Step 3: The generator uses a direct-drive motor to track the target output curve of the energy storage system and maximize the generator efficiency of the expansion power generation system to construct an objective function, set constraints, and determine the generator output curve P of each expansion power generation system. Eτt (τ=1、2、…、N);

[0083] Step 4: According to the generator output curve P of each expansion power generation system Eτt , according to the pressure range of the gas storage device when each expansion power generation system is in operation, the switch status of the corresponding gas storage device valve at each moment is judged to control the operation of the expansion power generation system;

[0084] Step 5: Based on the output requirements of each expansion power generation system, a maximum efficiency tracking algorithm is used to coordinate the control of the gas flow rate and the expansion ratio so that the expander of the compressed air energy storage system can still operate near its optimal speed when the power demand changes.

[0085] In one embodiment, in step 3, the mathematical expression for tracking the target output curve of the energy storage system is:

[0086]

[0087] Where t is the current analysis period, T is the total analysis period, P Et is the total power generation of the compressed air energy storage system during the expansion process during period t, that is, the total output curve of the generators of each expansion power generation system, P Ct P is the power consumed by the compressed air energy storage system during the compression process during period t,At is the target power of the compressed air energy storage system during period t;

[0088] The objective function for maximizing the generator efficiency of the expansion power generation system is:

[0089]

[0090] Where N is the total number of expansion power generation systems, τ is the τth expansion power generation system, P Eτt is the actual output of the τth expansion power generation system in period t, η Eτt is the generator operating efficiency of the τth expansion power generation system in period t, and its expression is:

[0091]

[0092] Where P Enτ is the rated power generation power of the τth expansion power generation system.

[0093] In one embodiment, in step 3, the constraint condition is:

[0094] The total output of each expansion power generation system in period t must meet the output demand of the energy storage system:

[0095] P E1t +P E2t +…+P ENt -P Et =0 (4)

[0096] The compression and expansion processes of the same gas storage device cannot be carried out at the same time:

[0097] P Clt ·P Elt =0 (5)

[0098] Where P Clt , P Elt They represent the power of the compression system and the expansion power generation system simultaneously connected to the gas storage device l at time t;

[0099] Compression power constraints of compressed air energy storage system:

[0100] P Cmin ≤P Ct ≤P Cmax (6)

[0101] Compressed air energy storage system expansion power constraints:

[0102] P Eτmin ≤P Eτt ≤P Eτmax (7)

[0103] The pressure p of the gas storage device connected to each expansion power generation system τt satisfies the following constraints:

[0104] p τmin ≤p τt ≤p τmax (8)

[0105] In one embodiment, step 4 includes:

[0106] Step 401: Define the pressure range of the gas storage device corresponding to each expansion power generation system, and sequentially divide them into pressure levels 1, 2,..., N in descending order;

[0107] Step 402: According to the generator output curve P of each expansion power generation system in step 3 Eτt , determine the expansion power generation systems participating in operation during the t period;

[0108] Step 403: Sort the expansion power generation systems participating in operation during the t period in descending order of power. According to the measured pressure of the gas storage device, with the goal of meeting and as close as possible to the pressure operation range of the expansion power generation system, sequentially select the matching gas storage device and control the operation of the expansion power generation system.

[0109] Expansion power generation systems with different power generation levels are divided into different power generation power levels according to different levels of the storage pressure of the gas storage device, and different levels of expanders and generators with different rated powers are connected to form expansion power generation systems with different power generation levels. Theoretically, as the remaining compressed air pressure of the gas storage device decreases, the rated power of the expansion power generation system also decreases.

[0110] The pressure level 1 corresponds to the pressure p0 of the gas storage device during the operation of the expansion power generation system, and the range of p0 is p2 ≤ p0 ≤ p1. The pressure level 2 corresponds to the pressure p3 of the gas storage device during the operation of the expansion power generation system, and the range of p3 is p5 ≤ p3 ≤ p4, where p4 < p2, that is, the upper limit of the pressure of the gas storage device corresponding to the expansion power generation system of pressure level N < the lower limit of the pressure of the gas storage device corresponding to the expansion power generation system of pressure level N - 1. The initial gas pressure of the gas storage device 1 and the gas storage device 2 is p1, the lowest pressure to drive the second expansion power generation system 4 is p2, and the lowest pressure to drive the first expansion power generation system 3 is p3, and p1 > p2 > p3.

[0111] In one embodiment, step 5 includes:

[0112] According to the required power P of each expansion power generation system Eτt , calculate the optimized expansion ratio π and optimized gas flow rate of the expander;

[0113] Obtain the optimized rotational speed ω according to the highest efficiency rotational speed optimization model *;

[0114] The electronic power transformer is controlled based on the optimized expansion ratio π and the optimized gas flow, so that the expander of the compressed air energy storage system can still run at the optimized speed ω when the power demand changes. * nearby.

[0115] The power generation process of the first expansion power generation system 3 is as follows:

[0116] When the gas storage device 1 drives the first expansion power generation system 3 to generate electricity: the third switch valve 53 is opened, the gas storage device 1 adjusts the output gas through the third throttle valve 63, and is connected to the third heat exchanger 43. The medium in the heat storage device is transmitted to the third heat exchanger 43 through the fifth switch valve 55 and the fifth throttle valve 65, and heats the inlet air of the first-stage expander 31 of the first expansion power generation system. After the gas is expanded by the first-stage expander 31 of the first expansion power generation system, it is connected to the fourth heat exchanger 44. The medium in the heat storage device is transmitted to the fourth heat exchanger 44 through the sixth switch valve 56 and the sixth throttle valve 66, and heats the inlet air of the second-stage expander 32 of the first expansion power generation system. The second-stage expander 32 expands again to do work, and the second-stage expander 32 of the first expansion power generation system is connected to the first generator 11 to drive the generator to generate electricity. When the gas pressure in the gas storage device 1 drops to p2 or the first expansion power generation system 3 exits operation according to the system operation requirements, the third switch valve 53, the fifth switch valve 55 and the sixth switch valve 56 are closed.

[0117] When the gas storage device 2 drives the first expansion power generation system 3 to generate electricity: the fourth switch valve 54 is opened, the gas storage device 2 adjusts the output gas through the fourth throttle valve 64, and is connected to the third heat exchanger 43. The medium in the heat storage device is transmitted to the third heat exchanger 43 through the fifth switch valve 55 and the fifth throttle valve 65, and heats the inlet air of the first-stage expander 31 of the first expansion power generation system. After the gas is expanded by the first-stage expander 31 of the first expansion power generation system, it is connected to the fourth heat exchanger 44. The medium in the heat storage device is transmitted to the fourth heat exchanger 44 through the sixth switch valve 56 and the sixth throttle valve 66, and heats the inlet air of the second-stage expander 32 of the first expansion power generation system. The second-stage expander 32 expands again to do work, and the second-stage expander 32 of the first expansion power generation system is connected to the first generator 11 to drive the generator to generate electricity. When the gas pressure in the gas storage device 2 drops to p2 or the first expansion power generation system 3 exits operation according to the system operation requirements, the fourth switch valve 54, the fifth switch valve 55 and the sixth switch valve 56 are closed.

[0118] The power generation process of the second expansion power generation system 4 is as follows:

[0119] When the gas storage device 1 drives the second expansion power generation system 4 to generate electricity: the seventh switch valve 57 is opened, the gas storage device 1 adjusts the output gas through the third throttle valve 63 and is connected to the fifth heat exchanger 45, the medium in the heat storage device is transmitted to the fifth heat exchanger 45 through the ninth switch valve 59 and the seventh throttle valve 67, and heats the inlet air of the first-stage expander 33 of the second expansion power generation system, and the gas is expanded by the first-stage expander 33 of the second expansion power generation system and connected to the second generator 12, driving the generator to generate electricity. When the gas pressure in the gas storage device 1 drops to p5 or the second expansion power generation system 4 exits operation according to the system operation requirements, the seventh switch valve 57 and the ninth switch valve 59 are closed.

[0120] When the gas storage device 2 drives the second expansion power generation system 4 to generate electricity: the eighth switch valve 58 is opened, the gas storage device 2 adjusts the output gas through the fourth throttle valve 64 and is connected to the fifth heat exchanger 45, the medium in the heat storage device is transmitted to the fifth heat exchanger 45 through the ninth switch valve 59 and the seventh throttle valve 67, and heats the inlet air of the first-stage expander 33 of the second expansion power generation system, and the gas is expanded by the first-stage expander 33 of the second expansion power generation system and connected to the second generator 12, driving the generator to generate electricity. When the gas pressure in the gas storage device 2 drops to p5 or the second expansion power generation system 4 exits operation according to the system operation requirements, the eighth switch valve 58 and the ninth switch valve 59 are closed.

[0121] According to the range of power P required by the energy storage system, the combined discharge mode of the first expansion power generation system 3 and the second expansion power generation system 4 is as follows:

[0122] (1) When the power required by the energy storage system P>P1, the first expansion power generation system 3 and the second expansion power generation system 4 work simultaneously;

[0123] (2) When the power required by the energy storage system changes dynamically or the compressed gas pressure is insufficient, the expansion power generation system needs to be switched from the first expansion power generation system 3 to the second expansion power generation system 4; When the power required by the energy storage system changes dynamically, the expansion power generation system needs to be switched from the second expansion power generation system 4 to the first expansion power generation system 3;

[0124] In the above combination scheme, it is preferred to use a gas storage device with a compressed air pressure in the range of p5 to p4 to drive the second expansion power generation system 4 to generate electricity.

[0125] Specifically, the operation process of the combined power generation mode (1) is as follows:

[0126] When the gas storage device 1 drives the first expansion power generation system 3 to generate electricity: the third switch valve 53 is opened, the gas storage device 1 adjusts the output gas through the third throttle valve 63 and is connected to the third heat exchanger 43, the medium in the heat storage device is transmitted to the third heat exchanger 43 through the fifth switch valve 55 and the fifth throttle valve 65, and heats the inlet air of the first-stage expander 31 of the first expansion power generation system, and after the gas is expanded by the first-stage expander 31 of the first expansion power generation system, it is connected to the fourth heat exchanger 44, and the medium in the heat storage device is transmitted to the fourth heat exchanger 44 through the sixth switch valve 56 and the sixth throttle valve 66, and heats the inlet air of the second-stage expander 32 of the first expansion power generation system, and the second-stage expander 32 expands again to do work, and the second-stage expander 32 of the first expansion power generation system is connected to the first generator 11 to drive the generator to generate electricity.

[0127] At the same time, when the gas storage device 2 drives the second expansion power generation system 4 to generate electricity: the eighth switch valve 58 is opened, the gas storage device 2 adjusts the output gas through the fourth throttle valve 64, and is connected to the fifth heat exchanger 45. The medium in the heat storage device is transmitted to the fifth heat exchanger 45 through the ninth switch valve 59 and the seventh throttle valve 67 to heat the inlet air of the first-stage expander 33 of the second expansion power generation system. After the gas is expanded by the first-stage expander 33 of the second expansion power generation system, it is connected to the second generator 12 to drive the generator to generate electricity.

[0128] In this power generation mode, the gas storage device with compressed air pressure in the range of p5 to p4 is preferably used to drive the expansion power generation system 4 to generate electricity. The connection between the gas storage devices 1 and 2 and the first expansion power generation system 3 and the second expansion power generation system 4 in the operation mode description can be exchanged according to the specific pressure and operation conditions.

[0129] The operation process of the combination mode (2) is as follows:

[0130] 1) When the power required by the energy storage system changes dynamically or the compressed gas pressure is insufficient, the expansion power generation system needs to be switched from the first expansion power generation system 3 to the second expansion power generation system 4. Close the sixth switch valve 56, the fifth switch valve 55, and the third switch valve 53, open the seventh switch valve 57 and the ninth switch valve 59, the gas storage device 1 adjusts the output gas through the third throttle valve 63, and connects to the fifth heat exchanger 45. The medium in the heat storage device is transmitted to the fifth heat exchanger 45 through the seventh throttle valve 67 and the ninth switch valve 59, and heats the inlet air of the first-stage expander 33 of the second expansion power generation system. The gas expands and performs work through the first-stage expander 33 of the second expansion power generation system, and the first-stage expander 33 of the second expansion power generation system is connected to the second generator 12 to drive the generator to generate electricity.

[0131] 2) When the power required by the energy storage system changes dynamically, the expansion power generation system needs to switch from the second expansion power generation system 4 to the first expansion power generation system 3. When the pressure in the gas storage devices 1 and 2 can drive the first expansion power generation system 3 to operate, the gas storage device 1 or 2 can be used to drive the first expansion power generation system 3. Here, the gas storage device 2 is used to drive the first expansion power generation system 3. At this time, the eighth switch valve 58 and the ninth switch valve 59 are closed, and the fourth switch valve 54, the fifth switch valve 55, and the sixth switch valve 56 are opened. The gas storage device 2 is connected to the first expansion power generation system 3 through the fourth throttle valve 64 and the fourth switch valve 54. During expansion power generation, the gas storage device 2 adjusts the output gas through the fourth throttle valve 64 and is connected to the third heat exchanger 43. The medium in the heat storage device is transmitted to the third heat exchanger 43 through the fifth throttle valve 65 and the fifth switch valve 55 to heat the inlet air of the first-stage expander 31 of the first expansion power generation system. After the gas is expanded by the first-stage expander 31 of the first expansion power generation system, it is heated again by the fourth heat exchanger 44 and transmitted to the second-stage expander 32 of the first expansion power generation system to expand again and perform work. The second-stage expander 32 of the first expansion power generation system is connected to the first generator 11 to drive the generator to generate electricity.

[0132] During the analyzed period t, corresponding to different output curves, there are the following situations:

[0133] ① When the initial gas storage pressure of the gas storage devices 1 and 2 is p1: when the first expansion power generation system 3 or the second expansion power generation system 4 works alone, the valve connected to the gas storage device 1 or 2 can be randomly selected to open; when the first expansion power generation system 3 and the second expansion power generation system 4 work simultaneously, the third switch valve 53 of the first expansion power generation system 3 connected to the gas storage device 1 is opened, and the eighth switch valve 58 of the second expansion power generation system 4 connected to the gas storage device 2 is opened.

[0134] ② When the initial pressure of the gas storage device 1 is greater than that of the gas storage device 2. The gas storage device 2 can drive the second expansion power generation system 4 to work. When the second expansion power generation system 4 works alone, the valve 58 connected to the gas storage device 2 is opened; the gas storage device 1 can drive the first expansion power generation system 3 to work. When the first expansion power generation system 3 works alone, the third switch valve 53 connected to the gas storage device 1 is opened; when the first expansion power generation system 3 and the second expansion power generation system 4 work at the same time, the valves connected to the gas storage devices 1 and 2 are opened respectively, and vice versa.

[0135] It is worth noting that the air intake switch valve 51 and the air outlet switch valve (the third switch valve 53 and the seventh switch valve 57) of the air storage device 1 will not open at the same time, and the air intake switch valve 52 and the air outlet switch valve (the fourth switch valve 54 and the eighth switch valve 58) of the air storage device 2 will not open at the same time.

[0136] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0137] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0138] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0139] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including" is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0140] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A control method for a compressed air energy storage system connected in parallel with an expansion power generation system, characterized in that: The method is used for a compressed air energy storage system in which an expansion power generation system is connected in parallel. The compressed air storage unit of the system includes a plurality of parallel gas storage devices. The expansion power generation unit includes a plurality of parallel expansion power generation systems with different rated power generation powers. The plurality of expansion power generation systems are respectively matched with different high-pressure gas pressure intervals. The method includes: Step 1: According to the pressure operating range of the gas storage device, the maximum rated power generation that can be driven and the power demand of the energy storage system, the number of parallel gas storage devices and expansion power generation systems of the parallel compressed air energy storage power generation system, the number of expanders of each expansion power generation system and the rated power generation power are determined based on the cascade utilization of the gas storage device pressure; Step 2, determining the target output curve of the compressed air energy storage system during the analysis period according to the wind and solar power output, power supply of the regional power grid and load power consumption, and power supply power curve; Step 3: Construct an objective function to track the target output curve of the energy storage system and maximize the generator efficiency of the expansion power generation system, set constraints, and determine the generator output curve of each expansion power generation system. ,in, Step 4: According to the generator output curve of each expansion power generation system , according to the pressure range of the gas storage device when each expansion power generation system is in operation, the switch status of the corresponding gas storage device valve at each moment is judged to control the operation of the expansion power generation system; Step 5: Based on the output requirements of each expansion power generation system, a maximum efficiency tracking algorithm is used to coordinate and control the gas flow rate and expansion ratio, so that when the power demand of the compressed air energy storage system changes, the expander can still operate near its optimal speed; In step 3, the mathematical expression for tracking the target output curve of the energy storage system is: Where t is the current analysis period, T is the total analysis period, P Et is the total power generation of the compressed air energy storage system during the expansion process during period t, that is, the total output curve of the generators of each expansion power generation system, P Ct P is the power consumed by the compressed air energy storage system during the compression process during period t, At is the target power of the compressed air energy storage system during period t; The objective function for maximizing the generator efficiency of the expansion power generation system is: Where N is the total number of expansion power generation systems, For the Expansion power generation system, For the The actual output of the expansion power generation system in period t, For the The generator operating efficiency of the expansion power generation system in period t is expressed as: In the formula, For the The rated power generation capacity of the expansion power generation system.

2. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: In step 3, the constraint condition is: The total output of each expansion power generation system in period t must meet the output demand of the energy storage system: P E1t +P E2t +…+P ENt -P Et =0; The compression and expansion processes of the same gas storage device cannot be carried out at the same time: P Clt ·P Elt =0; Where P Clt , P Elt They represent the power of the compression system and the expansion power generation system simultaneously connected to the gas storage device l at time t; Compression power constraints of compressed air energy storage system: P Cmin ≤P Ct ≤P Cmax ; Compressed air energy storage system expansion power constraints: Each expansion power generation system is connected to the gas storage device pressure The following constraints are met: 。 3. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The step 4 comprises: Step 401, clarifying the pressure range of the gas storage device corresponding to each expansion power generation system, and dividing them into pressure level 1, pressure level 2, ..., pressure level N in descending order; Step 402: according to the generator output curve of each expansion power generation system in step 3 , determine the expansion power generation system involved in operation during period t; Step 403, sort the expansion power generation systems participating in the operation in time period t from large to small according to power, select matching gas storage devices in sequence according to the measured pressure of the gas storage device, with the goal of meeting and being as close as possible to the pressure operating range of the expansion power generation system, and control the expansion power generation system to be put into operation.

4. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 3, characterized in that: The pressure level N corresponds to the upper limit of the pressure of the gas storage device for the expansion power generation system operation < the pressure level N-1 corresponds to the lower limit of the pressure of the gas storage device for the expansion power generation system operation.

5. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 3, characterized in that: The pressure level 1 corresponds to the pressure p0 of the gas storage device when the expansion power generation system is running, and the range of p0 is p2≦p0≦p1; the pressure level 2 corresponds to the pressure p3 of the gas storage device when the expansion power generation system is running, and the range of p3 is p5≦p3≦p4, and the range of p4 is <p2。 6. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 3, characterized in that: The step 5 comprises: According to the power demand of each expansion power generation system , calculate the optimal expansion ratio π and the optimal gas flow rate of the expander; According to the maximum efficiency speed optimization model, the optimal speed ω is obtained * ; The electronic power transformer is controlled based on the optimized expansion ratio π and the optimized gas flow, so that the expander of the compressed air energy storage system can still run at the optimized speed ω when the power demand changes. * nearby.

7. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 3, characterized in that: The compressed air energy storage system adjusts the operation and output of the parallel expansion power generation system according to the actual operation requirements of the power system to achieve different levels of power generation output. The different levels of power generation output include the output power of any single operation of the expansion power generation system 1 to N, or the output power of any two or more expansion power generation systems in combination.

8. The control method of the compressed air energy storage system in parallel with the expansion power generation system according to claim 5, characterized in that: The expansion power generation system at least includes a first expansion power generation system and a second expansion power generation system. The rated power generation of the first expansion power generation system is P1, and the rated power generation of the second expansion power generation system is P2, and P2 < P1. This system can achieve three different power generation combinations, namely, the first expansion power generation system works alone, the second expansion power generation system works alone, and the first expansion power generation system and the second expansion power generation system work simultaneously. The power generation powers of the three power generation modes are P1, P2, and P1 + P2 respectively; When the power required by the system P > P1, the first expansion power generation system and the second expansion power generation system work simultaneously; When it is necessary to switch the expansion power generation system from the first expansion power generation system to the second expansion power generation system due to the dynamic change of the power required by the system or the insufficient compressed gas pressure; or when it is necessary to switch the expansion power generation system from the second expansion power generation system to the first expansion power generation system due to the dynamic change of the power required by the energy storage system, the gas storage device with the compressed air pressure in the range of p5 to p4 is preferably used to drive the second expansion power generation system to generate electricity.

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