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

Abstract

The present invention relates to the technical field of electric energy storage, and specifically to a compressed air energy storage system in parallel with an expansion power generation system. The system includes a compression system, a compressed air storage unit, an expansion power generation unit, and a cold and hot storage unit. The compressed air storage unit 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. A plurality of different expansion power generation systems are connected to each parallel high-pressure gas storage device. The cold and hot storage unit includes a heat storage device and a cold storage device. The input end of the compression system is connected to surplus electric energy. The high-pressure gas output by the compression system is cooled by the heat exchange medium stored in the cold storage device and then input to the compressed air storage unit. The high-pressure gas output by the compressed air storage unit is heated by the heat exchange medium stored in the heat storage device and then input to the expander of the expansion power generation system. The system can realize a variety of power generation combinations, has a wider operating range, and has a higher compressed air utilization rate 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 compressed air energy storage system connected 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 system in parallel with an 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 compressed air energy storage system in parallel with an expansion power generation system, comprising a compression system, a compressed air storage unit, an expansion power generation unit and a cold and heat storage unit, wherein the compressed air storage unit comprises a plurality of parallel gas storage devices, the expansion power generation unit comprises a plurality of parallel expansion power generation systems, the plurality of expansion power generation systems are respectively matched with different high-pressure gas pressure intervals and have different operating power intervals, the number of the gas storage devices is not less than the number of the expansion power generation systems, the cold and heat storage unit comprises a heat storage device and a cold storage device, the input end of the compression system is connected to new energy sources such as wind power and photovoltaic power or a power grid, the compression system outputs high-pressure gas which is cooled by the cold storage device and then input to the compressed air storage unit, and the compressed air storage unit outputs high-pressure gas which is heated by the heat storage device and then input to the expander of the expansion power generation system. The inlet and exhaust temperatures of each stage of the compressor and the expander are controlled by adjusting the heat exchange medium flow of the heat exchanger.

[0006] More preferably, each air storage device in the compressed air storage unit is simultaneously connected to each expansion power generation system.

[0007] More preferably, the gas storage device and the expansion power generation system are connected via a switch valve.

[0008] More preferably, the air flow between the air storage device and the expansion power generation system is controlled by a throttle valve.

[0009] Preferably, the compression system comprises an electric motor, a first-stage compressor, a second-stage compressor, ..., an M-th-stage compressor, a first heat exchanger, a second heat exchanger, ..., an M-th-stage heat exchanger, and the electric motor, the first-stage compressor, the second-stage compressor, ..., and the M-th-stage compressor are connected in series in sequence;

[0010] The gas outlet of the i-th stage compressor is connected to the high-temperature gas inlet side of the i-th stage heat exchanger. After the high-temperature gas is cooled by the heat exchanger, the low-temperature gas outlet side of the i-th stage heat exchanger is connected to the inlet of the i+1-th stage compressor. The gas outlet of the M-th stage compressor is connected to the high-temperature gas inlet side of the M-th stage heat exchanger. After the high-temperature gas is cooled by the heat exchanger, the low-temperature gas outlet side of the M-th stage heat exchanger is connected to the compressed air storage unit.

[0011] The cold storage device is respectively connected to the low-temperature heat exchange medium inlet side of the first heat exchanger, the second heat exchanger, ..., and the Mth heat exchanger of the compression system. After the low-temperature heat exchange medium is heat exchanged by the heat exchanger, it is connected to the heat storage device from the high-temperature heat exchange medium outlet side of the heat exchanger, where i=1, 2, ..., M-1.

[0012] Preferably, the expansion power generation unit includes a first expansion power generation system, a second expansion power generation system, ..., an Nth expansion power generation system, and the rated power generation power of the jth expansion power generation system is P Nj , the rated power generation power of the j+1 expansion power generation system is P N(j+1) , and P N(j+1) <P Nj , j=1, 2,…, N-1.

[0013] More preferably, the second expansion and power generation system includes a first-stage heat exchanger of the second expansion and power generation system, a first-stage expander of the second expansion and power generation system, ..., an L-th stage heat exchanger of the second expansion and power generation system, an L-th stage expansion machine of the second expansion and power generation system and a second generator connected in sequence.

[0014] More preferably, the first expansion power generation system includes a first-stage heat exchanger of the first expansion power generation system, a first-stage expansion machine of the first expansion power generation system, a second-stage heat exchanger of the first expansion power generation system, a second-stage expansion machine of the first expansion power generation system, ..., a P-th stage heat exchanger of the first expansion power generation system, a P-th stage expansion machine of the first expansion power generation system and a first generator, which are connected in sequence.

[0015] Preferably, a heat exchanger is provided in front of each expansion machine of the expansion power generation system, and the output end of the compressed air storage unit is connected to the low-temperature gas inlet side of the heat exchanger in front of the expansion machine. 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 expansion machine inlet.

[0016] The heat storage devices are respectively connected to the high-temperature heat exchange medium inlet side of the expansion power generation unit heat exchanger. After the high-temperature heat exchange medium is heat exchanged by the heat exchanger, it is connected to the cold storage device from the low-temperature heat exchange medium outlet side of the heat exchanger.

[0017] Preferably, the generators in the expansion power generation units are all direct-drive motors.

[0018] The beneficial effects of the present invention are:

[0019] 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.

[0020] 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.

[0021] 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

[0022] Figure 1 It is a schematic diagram of system connection of the present invention;

[0023] Figure 2 It is a schematic diagram of the control flow of the method of the present invention;

[0024] 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, electric motor; 11, first generator; 12, second generator; 21, first-stage compressor; 22, second-stage compressor; 31, first-stage expander of the first expansion power generation system; 32, second-stage expander of the first expansion power generation system; 33, first-stage expander of the second expansion power generation system; 41, first heat exchanger; 42, second heat exchanger; 43, first expansion power generation system The first stage heat exchanger of the first expansion power generation system; 44, the second stage heat exchanger of the first expansion power generation system; 45, the first stage heat exchanger of the second expansion power generation system; 51, the first switch valve; 52, the second switch valve; 53, the third switch valve; 54, the fourth switch valve; 55, the fifth switch valve; 56, the sixth switch valve; 57, the seventh switch valve; 58, the eighth switch valve; 59, the ninth switch valve; 61, the first throttle valve; 62, the second throttle valve; 63, the third throttle valve; 64, the fourth throttle valve; 65, the fifth throttle valve; 66, the sixth throttle valve; 67, the seventh throttle valve. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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".

[0035] Embodiment 1

[0036] 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:

[0037] 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.

[0038] 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.

[0039] The compressed air storage unit in the system is composed of multiple parallel high-pressure gas storage devices. According to the original rated power generation of the compressed air energy storage system and the residual pressure of the gas storage device after the expansion process is completed, the lower limit of the pressure of the gas storage device is determined by comprehensively considering the efficiency of the compression link and the overall efficiency of the system, and an expansion power generation system is added. The rated power of the increased power generation system is less than the rated power generation of the original system to make full use of the residual gas in the gas storage device. The expansion power generation unit thus formed is composed of multi-stage or single-stage expanders with different rated power generation connected to generators.

[0040] The power generation system utilizes parallel high-pressure air storage chambers and parallel expansion power generation systems with different rated power generation powers. By controlling the operation mode of the expansion power generation system, the operation and output of the parallel expansion power generation system are adjusted according to the actual operation needs of the power system 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 achieves the functions of smoothing the output of wind power, photovoltaic power generation, and peak shaving and valley filling, the expansion power generation system works as close to the rated operating conditions as possible.

[0041] In this embodiment, the gas storage system is composed of two gas storage devices connected in parallel, and the expansion part is composed of two expansion power generation systems with different power generation capacities connected in parallel. The first expansion power generation system is a two-stage expansion, and the second expansion power generation system is a single-stage expansion. This embodiment is only a special case of the system. In this system, the compression system can be a multi-stage compression, the gas storage system can be composed of multiple gas storage devices connected in parallel, the expansion part can be composed of multiple expansion power generation systems connected in parallel, 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 first and second expansion power generation systems, without considering the extreme case where the remaining pressure of the gas storage device cannot drive the expansion power generation system.

[0042] In this embodiment, the gas storage system is composed of two gas storage devices connected in parallel, and the expansion part is composed of two expansion power generation systems with different rated power generation capacities connected in parallel. The first expansion power generation system is a two-stage expansion, and the second expansion power generation system is a single-stage expansion. The rated power generation capacity of the first expansion power generation system is P1, and the rated power generation capacity of the second expansion power generation system is P2, and P2 < P1. This system can achieve three different power generation combinations, that is, the first expansion power generation system works alone, the second expansion power generation system works alone, and the first and second expansion power generation systems work simultaneously, with three rated operating power points, that is, P1, P2, and P1 + P2.

[0043] In one embodiment, each gas storage device in the compressed air storage unit 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 intake of the gas storage device through a switch valve and controls the intake flow through a throttle valve. The outlet of each gas storage device controls the outlet of the gas storage device through a switch valve and controls the outlet flow through a throttle valve. The parallel gas storage devices are connected to the expanders of the expansion power generation systems with different power generation levels. The inlet of each expansion power generation system controls the 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 flow rate of the heat exchange medium of the heat exchanger is adjusted through a throttle valve to control the intake and exhaust temperatures of each stage of the expander.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In one embodiment, the second expansion power generation system 4 comprises a first stage heat exchanger 45 of the second expansion power generation system, a first stage expander 33 of the second expansion power generation system, and a second generator 12 connected in sequence;

[0049] 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 second-stage heat exchanger 44 of the first expansion power generation system, a second-stage expander 32 of the first expansion power generation system, and a first generator 11 connected in sequence;

[0050] 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 second-stage heat exchanger 44 of the first expansion power generation system through the sixth throttle valve 66 and the sixth switch valve 56; connected to the high-temperature heat exchange medium input end of the first-stage heat exchanger 45 of the second expansion power generation system 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 second-stage heat exchanger 44 of the first expansion power generation system, and the first-stage heat exchanger 45 of the second expansion power generation system are connected to the input end of the cold storage device.

[0051] Embodiment 2

[0052] 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:

[0053] Step 1: According to the pressure operating range of the gas storage device, the maximum rated power that can be driven and the power demand of the energy storage system, the operating pressure range of the gas storage device is determined by comprehensively considering the efficiency of the compression link and the overall efficiency of the system, and 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 are determined based on the cascade utilization of the gas storage device pressure;

[0054] Step 2, determine the target output curve of the compressed air energy storage system during the analysis period based on the power supply and consumption curves of new energy sources such as wind and solar power, power supply of the regional power grid and load power consumption; the output curve of the compressed air energy storage system can be determined according to existing methods, and the power supply and power consumption curves 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.

[0055] 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);

[0056] 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;

[0057] 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.

[0058] In one embodiment, in step 3, the mathematical expression for tracking the target output curve of the energy storage system is:

[0059]

[0060] 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;

[0061] The objective function for maximizing the generator efficiency of the expansion power generation system is:

[0062]

[0063] 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:

[0064]

[0065] Where P Enτ is the rated power generation power of the τth expansion power generation system.

[0066] In one embodiment, in step 3, the constraint condition is:

[0067] The total output of each expansion power generation system in period t must meet the output demand of the energy storage system:

[0068] P E1t +P E2t +…+P ENt -P Et =0 (4)

[0069] The compression and expansion processes of the same gas storage device cannot be carried out at the same time:

[0070] P Clt ·P Elt =0 (5)

[0071] 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;

[0072] Compression power constraints of compressed air energy storage system:

[0073] P Cmin ≤P Ct ≤P Cmax (6)

[0074] Compressed air energy storage system expansion power constraints:

[0075] P Eτmin ≤P Eτt ≤P Eτmax (7)

[0076] Each expansion power generation system is connected to the gas storage device pressure p τt The following constraints are met:

[0077] p τmin ≤p τt ≤p τmax (8)

[0078] In one embodiment, step 4 includes:

[0079] 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;

[0080] 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;

[0081] 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.

[0082] Expansion power generation systems with different power generation levels are divided into different power generation levels according to the different levels of storage pressure of the gas storage device. They are connected by expanders of different numbers and generators of different rated powers to form expansion power generation systems with different power generation levels. In theory, as the residual compressed air pressure of the gas storage device decreases, the rated power of the expansion power generation system also decreases.

[0083] Pressure level 1 corresponds to the pressure p0 of the gas storage device during the operation of the expansion power generation system. The range of p0 is p2 ≤ p0 ≤ p1. Pressure level 2 corresponds to the pressure p3 of the gas storage device during the operation of the expansion power generation system. The range of p3 is p5 ≤ p3 ≤ p4, where p4 < p2, that is, the upper limit of the gas storage device pressure corresponding to pressure level N during the operation of the expansion power generation system < the lower limit of the gas storage device pressure corresponding to pressure level N - 1 during the operation of the expansion power generation system. The initial gas pressure of gas storage device 1 and gas storage device 2 is p1. The minimum pressure to drive the first expansion power generation system 3 is p2, and the minimum pressure to drive the second expansion power generation system 4 is p5.

[0084] In one embodiment, step 5 includes:

[0085] According to the required power P of each expansion power generation system Eτt , the optimized expansion ratio π and optimized gas flow rate of the expander are calculated;

[0086] The optimized rotational speed ω is obtained according to the highest efficiency rotational speed optimization model * ;

[0087] Based on the optimized expansion ratio π and optimized gas flow rate, the electronic power transformer is controlled so that when the power demand of the compressed air energy storage system changes, the expander can still operate at the optimized rotational speed ω * nearby.

[0088] The power generation process of the first expansion power generation system 3 is as follows:

[0089] When gas storage device 1 drives the first expansion power generation system 3 to generate power: The third switching valve 53 is opened. 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 switching valve 55 and the fifth throttle valve 65 to heat the air at the inlet of the first-stage expander 31 of the first expansion power generation system. After the gas expands through the first-stage expander 31 of the first expansion power generation system, it is connected to the second-stage heat exchanger 44 of the first expansion power generation system. The medium in the heat storage device is transmitted to the second-stage heat exchanger 44 of the first expansion power generation system through the sixth switching valve 56 and the sixth throttle valve 66 to heat the air at the inlet of the second-stage expander 32 of the first expansion power generation system. The second-stage expander 32 expands and does work again. 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 power. When the gas pressure in gas storage device 1 drops to p2 or the first expansion power generation system 3 exits the operation according to the system operation requirements, the third switching valve 53, the fifth switching valve 55, and the sixth switching valve 56 are closed.

[0090] 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, and the gas is expanded by the first-stage expander 31 of the first expansion power generation system, and is connected to the second-stage heat exchanger 44 of the first expansion power generation system, and the medium in the heat storage device is transmitted to the second-stage heat exchanger 44 of the first expansion power generation system 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, and drives 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.

[0091] The power generation process of the second expansion power generation system 4 is as follows:

[0092] 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 first-stage heat exchanger 45 of the second expansion power generation system. The medium in the heat storage device is transmitted to the first-stage heat exchanger 45 of the second expansion power generation system 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. 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. 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.

[0093] 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 first-stage heat exchanger 45 of the second expansion power generation system. The medium in the heat storage device is transmitted to the first-stage heat exchanger 45 of the second expansion power generation system 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. 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. 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.

[0094] 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:

[0095] (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;

[0096] (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;

[0097] 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.

[0098] Specifically, the operation process of the combined power generation mode (1) is as follows:

[0099] 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 second-stage heat exchanger 44 of the first expansion power generation system, the medium in the heat storage device is transmitted to the second-stage heat exchanger 44 of the first expansion power generation system 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.

[0100] 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 first-stage heat exchanger 45 of the second expansion power generation system, and the medium in the heat storage device is transmitted to the first-stage heat exchanger 45 of the second expansion power generation system 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. 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.

[0101] 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.

[0102] The operation process of the combination mode (2) is as follows:

[0103] 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 first-stage heat exchanger 45 of the second expansion power generation system. The medium in the heat storage device is transmitted to the first-stage heat exchanger 45 of the second expansion power generation system through the seventh throttle valve 67 and the ninth switch valve 59, heating the inlet air of the first-stage expander 33 of the second expansion power generation system, and the gas expands and performs work through the first-stage expander 33 of the second expansion power generation system. 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.

[0104] 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 second-stage heat exchanger 44 of the first expansion power generation system 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.

[0105] During the analyzed period t, corresponding to different output curves, there are the following situations:

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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".

[0113] 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 compressed air energy storage system in parallel with an expansion power generation system, characterized in that: The 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 connected in parallel, the expansion power generation unit comprises a plurality of expansion power generation systems connected in parallel, the plurality of expansion power generation systems respectively matching different high-pressure gas pressure intervals and having different operating power intervals, the number of the gas storage devices is not less than the number of the expansion power generation systems, the cold and heat storage unit (6) comprises a heat storage device and a cold storage device, the input end of the compression system is connected to surplus electric energy, the high-pressure gas output by the compression system is cooled by the heat exchange medium stored in the cold storage device and then input to the compressed air storage unit (5), and the high-pressure gas output by the compressed air storage unit (5) is heated by the heat exchange medium stored in the heat storage device and then input to the expander of the expansion power generation system; Each air storage device in the compressed air storage unit (5) is simultaneously connected to each expansion power generation system; During the expansion power generation process, the system utilizes the remaining pressure of the gas storage device in stages according to the gas storage pressure range required for the operation of each expansion power generation system.

2. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The gas storage device and the expansion power generation system are connected to each other through a switch valve.

3. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The air flow between the air storage device and the expansion power generation system is controlled by a throttle valve.

4. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The compression system (2) comprises an electric motor (10), a first-stage compressor (21), a second-stage compressor (22), ..., an M-th-stage compressor, a first heat exchanger (41), a second heat exchanger (42), ..., an M-th-stage heat exchanger, wherein the electric motor (10), the first-stage compressor (21), the second-stage compressor (22), ..., and the M-th-stage compressor are connected in series in sequence; The gas outlet of the i-th stage compressor is connected to the high-temperature gas inlet side of the i-th stage heat exchanger. After the high-temperature gas is cooled by the heat exchanger, the low-temperature gas outlet side of the i-th stage heat exchanger is connected to the inlet of the i+1-th stage compressor. The gas outlet of the M-th stage compressor is connected to the high-temperature gas inlet side of the M-th stage heat exchanger. After the high-temperature gas is cooled by the heat exchanger, the low-temperature gas outlet side of the M-th stage heat exchanger is connected to the compressed air storage unit (5). The cold storage device is respectively connected to the low-temperature heat exchange medium inlet side of the first heat exchanger (41), the second heat exchanger (42), ..., and the M-th stage heat exchanger of the compression system. After the low-temperature heat exchange medium is heat exchanged by the heat exchanger, it is connected to the heat storage device from the high-temperature heat exchange medium outlet side of the heat exchanger, where i=1, 2, ..., M-1.

5. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The expansion power generation unit comprises a first expansion power generation system (3), a second expansion power generation system (4), ..., an Nth expansion power generation system, and the rated power generation power of the jth expansion power generation system is P Nj , the rated power generation power of the j+1 expansion power generation system is P N(j+1) , and P N(j+1) <P Nj , j=1, 2,…, N-1.

6. The compressed air energy storage system in parallel with the expansion power generation system according to claim 5, characterized in that: The second expansion power generation system (4) comprises a first-stage heat exchanger (45) of the second expansion power generation system, a first-stage expander (33) of the second expansion power generation system, ..., an L-th stage heat exchanger of the second expansion power generation system, an L-th stage expander of the second expansion power generation system and a second generator (12) connected in sequence.

7. The compressed air energy storage system in parallel with the expansion power generation system according to claim 5, characterized in that: The first expansion power generation system (3) comprises a first-stage heat exchanger (43) of the first expansion power generation system, a first-stage expansion machine (31) of the first expansion power generation system, a second-stage heat exchanger (44) of the first expansion power generation system, a second-stage expansion machine (32) of the first expansion power generation system, ..., a P-th stage heat exchanger of the first expansion power generation system, a P-th stage expansion machine of the first expansion power generation system and a first generator (11) connected in sequence.

8. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: A heat exchanger is respectively provided in front of each expander of each stage of the expansion power generation system, 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, and the low-temperature gas is heated by the heat exchanger and then connected to the inlet of the expander from the high-temperature gas outlet side of the heat exchanger; The heat storage devices are respectively connected to the high-temperature medium inlet side of the heat exchanger of the expansion system. After the high-temperature medium is heated by the heat exchanger to compress the gas, the low-temperature heat exchange medium outlet side of the heat exchanger is connected to the cold storage device. A switch valve is set on the high-temperature medium inlet side of the heat exchanger of the expansion system to control the circulation of the heat exchange medium. The equipment throttle valve controls the flow rate of the heat exchange medium, thereby controlling the inlet and exhaust temperature of each stage of the expander.

9. The compressed air energy storage system in parallel with the expansion power generation system according to claim 1, characterized in that: The generators in the expansion power generation units are all direct-drive motors.

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