A method for tracking and controlling compressed air energy storage coupled with wind power conversion

Abstract

The present invention discloses a method for tracking and controlling a compressed air energy storage coupled wind power variable power, the method comprising: being used in a wind storage power station, the wind storage power station comprising a wind power system and a compressed air energy storage system, the wind power system being connected to a power grid system, and also being connected to the power grid system through a compressed air energy storage system, the method comprising: detecting the system frequency of the power grid system, and calculating the frequency variation of the power grid system according to the system frequency; controlling the output power of the wind power system according to the frequency variation, or controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system or to discharge to the power grid system, so as to stabilize the system frequency. The method realizes the coordinated control of the compressed air energy storage system and the wind power system variable power tracking to participate in the primary frequency modulation of the power grid system, and realizes the maximization of the power generation efficiency by coordinating and controlling the power distribution of the compressed air energy storage system and the wind power system.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a compressed air energy storage coupled wind power conversion tracking control method. Background Art

[0002] Traditional doubly-fed induction wind turbines operate at the maximum power tracking point, that is, the rotor speed of the unit does not change in response to grid frequency fluctuations. Therefore, many studies have been conducted on the frequency response of wind turbines at home and abroad. Although overspeed load reduction control and variable pitch angle control can improve the overall performance and primary frequency regulation characteristics of wind turbines to a certain extent, the above methods all reserve a certain amount of spare capacity without achieving the maximum power generation benefit.

[0003] Although there have been relevant studies on the configuration of energy storage in wind farms, most of the related projects use electrochemical energy storage devices configured at the wind farm grid connection point. They are relatively small in scale and have a short service life, which brings about problems related to the safety, stability and environmental protection of electrochemical energy storage. Compressed air energy storage has been successfully configured on the grid side and achieved commercial operation due to its advantages such as large energy storage capacity, high site selection flexibility, low construction cost and long service life. However, traditional compressed air energy storage systems need to rely on natural gas supplementary combustion to provide heat sources, which have problems such as fuel dependence and emission pollution, and are easily restricted by natural gas sources. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to propose a compressed air energy storage coupled wind power variable power tracking control method, so as to achieve the coordinated control of the compressed air energy storage system and the wind power system variable power tracking to participate in the primary frequency modulation of the power grid system, and to achieve the maximum power generation efficiency by coordinating the power distribution of the compressed air energy storage system and the wind power system.

[0005] To achieve the above-mentioned purpose, the first aspect of the embodiment of the present invention proposes a compressed air energy storage coupled wind power conversion power tracking control method for a wind storage power station, wherein the wind storage power station comprises a wind power system and a compressed air energy storage system, wherein the wind power system is connected to a power grid system, and is also connected to the power grid system through the compressed air energy storage system, wherein the method comprises: detecting the system frequency of the power grid system, and calculating the frequency change of the power grid system according to the system frequency; controlling the output power of the wind power system according to the frequency change, or controlling the compressed air energy storage system to absorb the electric energy input by the wind power system to the power grid system or discharge to the power grid system, so as to stabilize the system frequency.

[0006] According to the variable power tracking control method of compressed air energy storage coupled with wind power according to the embodiment of the present invention, in order to improve the stability of the frequency of the power grid system, when the system frequency decreases, the compressed air energy storage system turbine unit is controlled to discharge and the electric energy is transmitted to the power grid side to achieve the primary frequency regulation of the system. When the system frequency increases, on the one hand, the power on the power grid side is absorbed by controlling the charging of the compressed air energy storage system compressor, and on the other hand, the wind turbine is in the variable power point tracking control mode, and the output power of the wind turbine unit is reduced by increasing the rotor speed of the wind turbine unit, so that the wind storage power station has the ability to regulate the primary frequency under all working conditions.

[0007] In addition, the compressed air energy storage coupled wind power conversion tracking control method proposed in the above embodiment of the present invention may also have the following additional technical features:

[0008] According to one embodiment of the present invention, the compressed air energy storage system is controlled to absorb the electric energy of the power grid system or discharge to the power grid system according to the frequency change, including: if the frequency change is greater than 0, the compressed air energy storage system is controlled to discharge to the power grid system according to the frequency change; if the frequency change is less than or equal to 0, the compressed air energy storage system is controlled to absorb the electric energy input from the wind power system to the power grid system according to the frequency change.

[0009] According to one embodiment of the present invention, controlling the output power of the wind power system according to the frequency change includes: when the frequency change is greater than 0, controlling the rotational speed of the wind turbine rotor in the wind power system according to the frequency change to reduce the output power of the wind power system.

[0010] According to one embodiment of the present invention, controlling the compressed air energy storage system to discharge to the power grid system according to the frequency change includes: calculating the difference between the system frequency and the system rated frequency to obtain a first frequency change; calculating the increased power of the power grid system according to the first frequency change and the energy storage droop coefficient; determining the target power generation power of the turbine in the compressed air energy storage system according to the increased power, and controlling the turbine to operate at the target power generation power to discharge to the power grid system.

[0011] According to one embodiment of the present invention, controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system according to the frequency change includes: controlling the compressor in the compressed air energy storage system to operate at maximum power to absorb the electric energy input from the wind power system to the power grid system.

[0012] According to one embodiment of the present invention, controlling the rotational speed of the wind turbine rotor in the wind power system according to the frequency change includes: calculating the difference between the system frequency and the system rated frequency to obtain a second frequency change; calculating the reduced power of the power grid system according to the second frequency change and the active power-frequency droop coefficient of the thermal power unit; calculating the power difference between the reduced power and the maximum power, and determining the target rotational speed of the wind turbine rotor according to the power difference, and controlling the wind turbine rotor according to the target rotational speed.

[0013] According to an embodiment of the present invention, a power-speed table is used to determine the target speed of the wind turbine rotor according to the power difference.

[0014] According to an embodiment of the present invention, a variable power point tracking control method is adopted to control the wind turbine rotor according to the target speed.

[0015] According to an embodiment of the present invention, the wind turbine generator set is a doubly-fed wind turbine generator set.

[0016] According to one embodiment of the present invention, the compressed air energy storage system adopts a two-stage compression and two-stage expansion compressed air energy storage system.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of a compressed air energy storage coupled wind power conversion tracking control method according to an embodiment of the present invention;

[0019] Figure 2 This is a block diagram of a compressed air energy storage coupled with wind power conversion tracking primary frequency modulation control according to an embodiment of the present invention;

[0020] Figure 3 is a flow chart of controlling a compressed air energy storage system to discharge to a power grid system according to an embodiment of the present invention;

[0021] Figure 4 is a power control block diagram of a turbine of a compressed air energy storage system according to an embodiment of the present invention;

[0022] Figure 5 is a power control block diagram of a compressor of a compressed air energy storage system according to an embodiment of the present invention;

[0023] Figure 6 is a flow chart of reducing the output power of a wind power system according to an embodiment of the present invention;

[0024] Figure 7is a schematic diagram of a wind turbine generator set according to a specific embodiment of the present invention;

[0025] Figure 8 It is a schematic diagram of a compressed air energy storage system according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] The following is attached to the instruction manual Figure 1-8 And a specific implementation method is described in detail for a compressed air energy storage coupled wind power conversion tracking control method of an embodiment of the present invention.

[0028] The compressed air energy storage coupled wind power conversion tracking control method of the embodiment of the present invention is used in a wind storage power station, which includes a wind power system and a compressed air energy storage system. The wind power system is connected to a power grid system and is also connected to the power grid system through the compressed air energy storage system.

[0029] Specifically, the wind power system in the wind storage power station is not only connected to the power grid system, but also connected to the power grid system through a compressed air energy storage system. Among them, the compressed air energy storage system is connected to the wind power system to store the electricity generated by the wind power system. The compressed air energy storage system in the embodiment of the present invention is a non-supplementary advanced adiabatic compressed air energy storage system based on compression heat feedback, which has the advantages of high efficiency and environmental protection and pollution-free.

[0030] In an embodiment of the present invention, the wind power generator set of the wind power system is mainly composed of a wind turbine, a gearbox, a generator, a grid-side converter and a rotor-side converter, and the control of the wind power system includes pitch angle control, machine-side and grid-side converter control.

[0031] In an embodiment of the present invention, a compressed air energy storage system includes a compressor, a turbine, a heat exchanger, a heat storage tank, a gas storage reservoir, an electric motor and a synchronous generator, and the compressed air energy storage system control includes a power control system of the compressor and the turbine.

[0032] Figure 1 FIG. 1 is a flow chart of a method for controlling compressed air energy storage coupled with wind power conversion power tracking according to an embodiment of the present invention. Figure 1 As shown, the compressed air energy storage coupled wind power conversion power tracking control method may include:

[0033] S101, detecting a system frequency of a power grid system, and calculating a frequency change of the power grid system according to the system frequency;

[0034] S102, controlling the output power of the wind power system according to the frequency change, or controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system or to discharge the electric energy to the power grid system, so as to stabilize the system frequency.

[0035] It should be noted that a sudden increase or decrease in grid load will cause a change in the grid system frequency, and the stability of the grid system frequency is crucial to the normal operation of the power system. If the frequency fluctuates too much, it will cause damage to power equipment and even cause the collapse of the power system.

[0036] In order to stabilize the frequency of the power grid system, the system frequency of the power grid system is detected, and the frequency change of the power grid system within a preset time is calculated based on the detected system frequency, so as to adjust the output power of the wind power system according to the frequency change, or control the compressed air energy storage system to absorb the electric energy input by the wind power system to the power grid system or discharge to the power grid system, so as to stabilize the system frequency of the power grid system.

[0037] Specifically, when the system frequency decreases, the compressed air energy storage system is controlled to discharge and transmit electric energy to the grid side to realize the primary frequency regulation function of the system. If the system frequency increases, the wind power system and the compressed air energy storage system are coordinated to control the charging of the compressed air energy storage system on the one hand to absorb the power input from the wind power system to the grid side, and on the other hand, the wind turbine increases the speed and reduces the power on the basis of the maximum power tracking mode to realize the variable power point tracking control for primary frequency regulation.

[0038] It should be noted that the preset time can be set according to actual needs, and the embodiment of the present invention does not limit the preset time.

[0039] In one embodiment of the present invention, Figure 2 As shown, controlling the compressed air energy storage system to absorb electric energy from the grid system or discharge to the grid system according to the frequency variation may include:

[0040] If the frequency change is greater than 0, the compressed air energy storage system is controlled to discharge to the power grid system according to the frequency change;

[0041] If the frequency change is less than or equal to 0, the compressed air energy storage system is controlled according to the frequency change to absorb the electric energy input from the wind power system to the power grid system.

[0042] Specifically, the load connected to the power grid system increases suddenly, causing the system frequency f sThe frequency change is greater than 0. Since the wind power system is controlled by Maximum Power Point Tracking (MPPT), the compressed air energy storage system is controlled to discharge to the power grid system according to the frequency change to stabilize the system frequency of the power grid system. The load connected to the power grid system is suddenly reduced, and the sudden reduction in load causes the system frequency f s Increase, the frequency change is less than or equal to 0, at this time, the compressed air energy storage system can be controlled to absorb the electric energy input from the wind power system to the power grid system according to the frequency change, and the output power of the wind power system can be adjusted according to the frequency change to stabilize the system frequency of the power grid system.

[0043] As a specific embodiment, Figure 3 As shown, controlling the compressed air energy storage system to discharge to the grid system according to the frequency change may include:

[0044] S201, calculating the difference between the system frequency and the system rated frequency to obtain a first frequency variation;

[0045] S202, calculating the increased power of the power grid system according to the first frequency change amount and the energy storage droop coefficient;

[0046] S203, determining the target power generation power of the turbine in the compressed air energy storage system according to the increased power, and controlling the turbine to operate at the target power generation power to discharge to the power grid system.

[0047] Specifically, when the frequency variation is greater than 0, according to the system frequency f s With the system rated frequency f N The calculated first frequency change Δf1, where Δf1 = f N -f s Since the wind turbine is in the maximum power tracking state, the turbine of the compressed air energy storage system can be controlled to generate electricity to participate in the system frequency regulation. According to the first frequency change Δf1 and the energy storage droop coefficient k p The increased power ΔP1 of the power grid system is calculated. In this embodiment, ΔP1=k p (f N -f s ), where k p is the energy storage droop coefficient, f N is the rated frequency of the system, f s The increased power ΔP1 is used as the target power generation of the turbine in the compressed air energy storage system, and the turbine is controlled to operate at the target power generation to discharge to the power grid system, thereby quickly stabilizing the system frequency of the power grid system.

[0048] In the embodiment of the present invention, the power control of the turbine of the compressed air energy storage system is as follows: Figure 4 As shown. It uses a throttle valve to change the inlet air mass flow of the compressed air energy storage system turbine to adjust the output power of the turbine power generation system. Among them, Figure 4 P t,ref represents the reference power of the expander, P t Represents the output power value of the expander, T air,out is the outlet temperature of the air after passing through the heat exchanger, T air,in is the inlet temperature of the air before entering the heat exchanger, T HTF,in is the inlet temperature of the heat medium before entering the heat exchanger; τ TD and τ AV is the time delay coefficient of the nozzle regulator and expansion process, τ TP is the delay coefficient of the power sensor, m t is the turbine inlet air mass flow rate.

[0049] As a specific embodiment, controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system according to the frequency change amount may include:

[0050] The compressor in the compressed air energy storage system is controlled to operate at maximum power to absorb the electric energy input from the wind power system to the power grid system.

[0051] Specifically, when the frequency change is less than or equal to 0, the compressor (motor) of the compressed air energy storage system is controlled to start. In order to quickly stabilize the system frequency of the power grid system, the motor in the compressed air energy storage system is controlled to operate at the maximum power ΔP c The wind power system operates at full power and absorbs the electric energy input from the wind power system to the power grid system at maximum power.

[0052] As a specific embodiment, the power control of the compressor of the advanced compressed air energy storage system is as follows: Figure 5 As shown in the figure, the compressor inlet air mass flow rate can be controlled by changing the inlet guide vane angle to adjust the mechanical power of the compressor. The dynamic characteristics of the compressor inlet guide vane angle control and the time delay link of the compression process are approximately described by the first-order inertia link, where Figure 5 P c,ref Indicates the reference power of the compressor, P c Indicates the output power value of the compressor. is the compressor inlet temperature, is the compressor outlet temperature; τ IGV and τ cd is the time delay coefficient of the IGV (Inlet guide vanes) system and the compression process; τ cp is the delay coefficient of the power sensor, m cis the compressor inlet air mass flow rate, Lmin and lmax are the maximum and minimum intake air mass flow rates to prevent the compressor from blocking and surging.

[0053] In one embodiment of the present invention, Figure 2 As shown, the output power of the wind power system is controlled according to the frequency variation, including:

[0054] When the frequency variation is less than or equal to 0, the rotation speed of the wind turbine rotor in the wind power system is controlled according to the frequency variation to reduce the output power of the wind power system.

[0055] Specifically, when the frequency variation is less than or equal to 0, the output power of the wind power system can be reduced by controlling the rotation speed of the wind turbine rotor in the wind power system, thereby further quickly stabilizing the system frequency of the power grid system.

[0056] In an embodiment of the present invention, Figure 2 Medium ref Indicates the direct output power of the wind turbine (mainly the output power P of the doubly fed induction generator under the wind turbine MPPT control w With additional variable power point tracking control ΔP w (k w Δf) and ω ref Indicates the rated speed of the fan, Δω=ω ref -ω r .

[0057] As a specific embodiment, Figure 6 As shown, the speed of the wind turbine rotor in the wind power system is controlled according to the frequency variation, including:

[0058] S301, calculating the difference between the system frequency and the system rated frequency to obtain a second frequency variation;

[0059] S302, calculating the reduced power of the power grid system according to the second frequency variation and the active power-frequency droop coefficient of the thermal power unit;

[0060] S303, calculating the power difference between the reduced power and the maximum power, determining the target speed of the wind turbine rotor according to the power difference, and controlling the wind turbine rotor according to the target speed.

[0061] Specifically, according to the system frequency f s With the system rated frequency f N The calculated second frequency change Δf2, where Δf2 = f N -f s According to the second frequency variation Δf2 and the active power-frequency droop coefficient K′ of the thermal power unit pThe reduced power ΔP2 of the power grid system is calculated. In this embodiment, ΔP2 = -k' p (f N -f s ), where -k′ p is the active power-frequency droop coefficient of the thermal power unit, f N is the rated frequency of the system, f s is the system frequency. The difference between the reduced power ΔP2 and the maximum power of the motor in the compressed air energy storage system is calculated to obtain the power difference. The target speed of the wind turbine rotor is determined according to the power difference, and the wind turbine rotor is controlled according to the target speed. By increasing the wind turbine rotor speed, the wind turbine variable power point tracking control is achieved, the active power output of the unit is reduced, and the compressed air energy storage and the wind turbine jointly participate in the primary frequency regulation of the power grid.

[0062] In one embodiment of the present invention, a power-rotation speed table may be used to determine the target rotation speed of the wind turbine rotor according to the power difference.

[0063] Specifically, according to the power difference, a power-speed table is queried to obtain a target speed of the wind turbine rotor.

[0064] In the embodiment of the present invention, during the primary frequency modulation power distribution process, the compressed air energy storage is given priority to absorb electric energy at full power, and the wind turbine adopts the variable power point tracking control method to reduce the active power of the wind turbine. The droop coefficient k of the wind turbine is w for:

[0065]

[0066] Among them, ΔP2 is the reduced power of the power grid system, P c is the output power of the compressor in the compressed air energy storage system, f N is the rated frequency of the system, f s is the system frequency.

[0067] Specifically, when the system load decreases and the overall frequency of the power grid system increases, the power grid detects the change in system frequency, and coordinates and controls the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system and the wind turbine speed to increase and reduce power to maintain system power balance. At the same time, the droop coefficient of the wind turbine variable power tracking is obtained to achieve system frequency regulation.

[0068] In one embodiment of the present invention, a variable power point tracking control method is adopted to control the rotor of the wind turbine generator set according to the target speed.

[0069] Specifically, the embodiment of the present invention uses a variable power point tracking control method to control the wind turbine generator set.

[0070] The compressed air energy storage coupled wind power variable power tracking control method of the embodiment of the present invention is to improve the stability of the frequency of the power grid system. When the system frequency decreases, the compressed air energy storage system turbine unit is controlled to discharge and the electric energy is transmitted to the power grid side to achieve the primary frequency regulation of the system. When the system frequency increases, on the one hand, the power input from the wind power system to the power grid side is absorbed by controlling the charging of the compressed air energy storage system compressor. On the other hand, the wind turbine is in the variable power point tracking control mode, and the output power of the wind turbine unit is reduced by increasing the rotor speed of the wind turbine unit, so that the wind storage power station has the ability to regulate the primary frequency under all working conditions.

[0071] In an embodiment of the present invention, when the system frequency increases, the compressed air energy storage is preferentially used to absorb electric energy at full power, and then the wind turbine is controlled to reduce active power by variable power point tracking control. The wind power droop coefficient is calculated by simulating the difference between the power compensation required for frequency regulation of the wind turbine and the power compensation of the compressor of the compressed air energy storage system. The embodiment of the present invention realizes the coordinated control of the compressed air energy storage power station and the wind turbine variable power tracking to participate in the primary frequency regulation of the power grid system, and realizes the maximization of power generation efficiency by coordinating and controlling the power distribution of the compressed air energy storage system and the wind power system.

[0072] In one embodiment of the present invention, the wind turbine generator set may be a doubly-fed wind turbine generator set.

[0073] As a specific example, Figure 7 As shown, the wind power system of an embodiment of the present invention includes a wind turbine, a gearbox, a doubly fed induction generator, a rotor-side converter and a grid-side converter, wherein the wind turbine is connected to the input end of the doubly fed induction generator through the gearbox, the first output end of the doubly fed induction generator is connected to the input end of the rotor-side converter, the first output end of the rotor-side converter is connected to the first end of the first capacitor, the second output end of the rotor-side converter is connected to the second end of the first capacitor, the first end of the first capacitor is connected to the first input end of the grid-side converter, the second end of the first capacitor is connected to the second input end of the grid-side converter, the output end of the grid-side converter is connected to the transformer through the inductor, and the second output end of the doubly fed induction generator is connected to the transformer.

[0074] This specific embodiment takes a wind power system using a doubly-fed wind turbine as an example. The wind power system is mainly composed of a wind turbine, a gearbox, a doubly-fed induction generator (DFIG), a grid-side converter (GSC) and a rotor-side converter (RSC). According to the aerodynamic equation of the wind turbine, the mechanical power P output by the wind power system can be obtained. m As shown below:

[0075]

[0076] Where ρ is air density, A is swept area, v is wind speed, λ is tip speed ratio, β is pitch angle, C pw is the wind energy utilization coefficient, R is the radius of the wind rotor blade, ω r is the rotor speed of the doubly-fed induction generator.

[0077] In this specific embodiment, the transmission model of the wind turbine generator set is simplified to the following formula:

[0078]

[0079] Among them, H wt is the total inertia time constant of the wind power system, P m is the mechanical power output of the wind power system, P w is the output power of the doubly-fed induction generator.

[0080] It should be noted that the control part of the wind power system includes pitch angle control, machine-side and grid-side converter control. In order to facilitate the control of the speed of the doubly-fed induction generator so that it runs at the optimal speed to achieve maximum power point tracking, the rotor converter vector control model adopts a torque-current dual closed-loop control system to realize the control of the doubly-fed motor. For the control of reactive power, a control method of reactive power outer loop and current inner loop is adopted. The control goal of the grid-side converter is to keep the DC bus voltage stable, and it adopts a dual closed-loop control system of DC bus voltage outer loop and AC side current inner loop. The DC bus voltage is used as the outer loop control target, the output of the voltage controller is used as the setting of the current inner loop, and the current controller controls the AC side current to quickly track the current command.

[0081] In one embodiment of the present invention, the compressed air energy storage system may adopt a two-stage compression and two-stage expansion compressed air energy storage system.

[0082] As a specific example, Figure 8As shown, the compressed air energy storage system of the embodiment of the present invention includes a motor, a compression subsystem, an air storage subsystem, a turbine subsystem, a generator, a compression heat collection subsystem, and a compression heat feedback subsystem. The compression subsystem includes a low-pressure compressor (LP) and a high-pressure compressor (HP). The turbine subsystem includes a high-pressure turbine (HT) and a low-pressure turbine (LT). The compression heat collection subsystem includes a first heat exchanger, a second heat exchanger, a high-temperature heat storage tank, and a normal-temperature heat storage tank. The compression heat feedback subsystem includes a recuperative heat exchanger and a third heat exchanger, wherein the output end of the motor is connected to the input end of the low-pressure compressor, the first output end of the low-pressure compressor is connected to the first input end of the high-pressure compressor, the second output end of the low-pressure compressor is connected to the first input end of the first heat exchanger, the first output end of the first heat exchanger is connected to the second input end of the high-pressure compressor, the output end of the high-pressure compressor is connected to the first input end of the second heat exchanger, the first output end of the second heat exchanger is connected to the input end of the gas storage reservoir through a first solenoid valve, the output end of the gas storage reservoir is connected to the first input end of the third heat exchanger through a second solenoid valve, and the third heat exchanger The first output end of the high-pressure turbine is connected to the input end of the high-pressure turbine, the output end of the high-pressure turbine is connected to the first input end of the recuperator, the first output end of the recuperator is connected to the input end of the low-pressure turbine, the output end of the low-pressure turbine is connected to the generator, the output end of the normal temperature heat storage tank is connected to the first end of the first three-way valve, the second end of the first three-way valve is connected to the second input end of the first heat exchanger, the third end of the first three-way valve is connected to the second input end of the second heat exchanger, the second output end of the first heat exchanger is connected to the first end of the second three-way valve, and the second heat exchanger The second output end of is connected to the second end of the second three-way valve, the third end of the second three-way valve is connected to the input end of the high-temperature heat storage tank, the output end of the high-temperature heat storage tank is connected to the first end of the third three-way valve, the second end of the third three-way valve is connected to the second input end of the recuperative heat exchanger, the second output end of the recuperative heat exchanger is connected to the first end of the fourth three-way valve, the third end of the third three-way valve is connected to the second input end of the third heat exchanger, the second output end of the third heat exchanger is connected to the second end of the fourth three-way valve, and the third end of the fourth three-way valve is connected to the input end of the normal temperature heat storage tank.

[0083] This specific embodiment takes the typical two-stage compression and two-stage expansion compressed air energy storage system structure as an example. The compressed air energy storage system structure is mainly composed of a compressor, a turbine, a heat exchanger, a heat storage tank (thermal oil tank), a gas storage reservoir (high-pressure air), an electric motor, and a synchronous generator. Among them, the compression subsystem composed of a multi-stage compressor and an intercooling heat exchanger and the power generation subsystem composed of a multi-stage turbine and a reheat heat exchanger are the core components of the energy storage and energy release processes, respectively, and the two are coupled through the heat storage tank and the gas storage tank.

[0084] In the compressed air energy storage coupled wind power variable power tracking control method of the embodiment of the present invention, the primary frequency regulation control is completed by the coordinated control of the compressed air energy storage system and the wind turbine. If the system frequency decreases, the compressed air energy storage system is preferentially controlled to charge at full power to absorb the excess energy output by the wind turbine, and at the same time, the speed of the wind turbine is controlled to achieve variable power point tracking to reduce the output power. If the system frequency increases, the compressed air energy storage system is controlled to discharge to meet the spare capacity supply required for primary frequency regulation, so that the wind storage power station has the ability to regulate the primary frequency under all working conditions. At the same time, a power allocation method for the compressed air energy storage system and the wind power system is proposed to determine the droop coefficient of the variable power point tracking control of the wind turbine and improve the frequency stability of the system.

[0085] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0086] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0089] 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0090] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0091] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0092] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A compressed air energy storage coupled wind power conversion power tracking control method, characterized in that: Used in a wind power station, the wind power station includes a wind power system and a compressed air energy storage system, the wind power system is connected to a power grid system, and is also connected to the power grid system through the compressed air energy storage system, the method includes: Detecting a system frequency of the power grid system, and calculating a system frequency change of the power grid system according to the system frequency; Controlling the output power of the wind power system according to the system frequency variation, and controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system or to discharge to the power grid system, so as to stabilize the system frequency; Wherein, controlling the output power of the wind power system according to the system frequency variation includes: When the system frequency variation is less than or equal to 0, the speed of the wind turbine rotor in the wind power system is controlled according to the system frequency variation to reduce the output power of the wind power system; wherein, controlling the speed of the wind turbine rotor in the wind power system according to the system frequency variation includes: Calculating the difference between the system frequency and the system rated frequency to obtain a second frequency variation; The reduced power of the power grid system is calculated according to the second frequency variation and the active power-frequency droop coefficient of the thermal power unit; The power difference between the reduced power and the maximum power of the compressor in the compressed air energy storage system is calculated, and a target speed of the wind turbine rotor is determined according to the power difference, and the wind turbine rotor is controlled according to the target speed.

2. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 1 is characterized in that: Controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system or to discharge to the power grid system according to the system frequency change amount includes: If the system frequency change is greater than 0, controlling the compressed air energy storage system to discharge to the power grid system according to the system frequency change; If the system frequency change is less than or equal to 0, the compressed air energy storage system is controlled according to the system frequency change to absorb the electric energy input from the wind power system to the power grid system.

3. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 2 is characterized in that: The method of controlling the compressed air energy storage system to discharge to the power grid system according to the system frequency variation comprises: Calculating the difference between the system frequency and the system rated frequency to obtain a first frequency change; Calculate the increased power of the power grid system according to the first frequency change and the energy storage droop coefficient; The target power generation power of the turbine in the compressed air energy storage system is determined according to the increased power, and the turbine is controlled to operate at the target power generation power to discharge to the power grid system.

4. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 2 is characterized in that: The method of controlling the compressed air energy storage system to absorb the electric energy input from the wind power system to the power grid system according to the system frequency variation comprises: The compressor in the compressed air energy storage system is controlled to operate at maximum power to absorb the electric energy input from the wind power system to the power grid system.

5. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 1 is characterized in that: The target speed of the wind turbine rotor is determined according to the power difference using a power-speed table.

6. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 1 is characterized in that: A variable power point tracking control method is adopted to control the wind turbine rotor according to the target speed.

7. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 1 is characterized in that: The wind turbine generator set adopts a double-fed wind turbine generator set.

8. The compressed air energy storage coupled wind power conversion power tracking control method according to claim 1 is characterized in that: The compressed air energy storage system adopts a two-stage compression and two-stage expansion compressed air energy storage system.

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