Single-machine variable-speed compressed air energy storage power station and electromagnetic vibration suppression method thereof

Abstract

This invention discloses a single-unit variable-speed compressed air energy storage power station and its electromagnetic vibration suppression method. The power station includes a generator motor, a compressor, an expander, an air storage tank, and a partial power converter system. The generator motor includes a stator power winding, a stator control winding, and a squirrel-cage rotor, without brushes or slip rings. The three-phase lines of the stator power winding are connected to the power grid, and the stator control winding is connected to the partial power converter system. The generator motor can switch between motoring and generating modes. The method obtains the vibration frequency components based on the magnetic field distribution and eccentricity analysis of the generator motor. By embedding an electromagnetic vibration observer and a vibration negative feedback closed-loop control architecture in the excitation control system, compensation current is injected in a reverse superposition manner to suppress vibration and improve operational stability over a wide speed range.

Description

Technical Field

[0001] This invention belongs to the field of compressed air energy storage technology, specifically relating to a single-unit variable-speed compressed air energy storage power station and its electromagnetic vibration suppression method. Background Technology

[0002] Compressed air energy storage (CASS) is an important large-scale physical energy storage method. Its basic principle is to use surplus electricity to drive a compressor during off-peak hours to compress air and store it in a high-pressure container. During peak hours, the stored compressed air is released to drive an expander to perform work, which is then used to generate electricity that is fed back to the grid. This technology has advantages such as large storage capacity, long storage period, and high system efficiency, making it an important means of peak shaving and valley filling in power systems and for absorbing fluctuations in renewable energy.

[0003] Traditional compressed air energy storage systems typically employ fixed-speed units based on synchronous generators, which struggle to effectively address the volatility and intermittency of renewable energy generation, and their operating efficiency drops significantly under partial load conditions. To overcome these technical bottlenecks, variable-speed compressed air energy storage technology has become an important development direction. Its core lies in using variable-speed devices such as doubly-fed generator motors or direct-drive generator motors to achieve adaptive speed matching between the expander and the generator, thereby significantly improving the overall operating efficiency of the system.

[0004] In variable-speed compressed air energy storage systems, the generator motor is the core component, and its operating status directly affects the system's efficiency and safety. Variable-speed generator motors, due to their adjustable operating speed over a wide range, offer flexibility but also introduce more complex vibration issues than fixed-speed motors. The root cause of variable-speed generator motor vibration is unbalanced electromagnetic force, primarily caused by two factors: first, uneven air gap between the stator and rotor, resulting from design and manufacturing tolerances, installation errors, etc., leading to variations in the static air gap; second, the coupling of multiple windings, where harmonics in the winding magnetic field excite electromagnetic imbalance forces. If these vibrations are not controlled, they will seriously jeopardize equipment safety, lifespan, and system stability.

[0005] Traditional methods for suppressing electromagnetic vibration in fixed-speed generator-motors (GM-Ms) require addressing three aspects: power supply, stator, and rotor conditions. These include optimizing power supply quality to ensure three-phase voltage balance and eliminate phase loss and harmonic interference; repairing stator winding faults to restore magnetic field symmetry; and addressing rotor issues, such as repairing broken rotor bars, correcting core deformation, and adjusting dynamic balance to reduce air gap flux imbalance. However, these traditional methods are poorly suited for variable-speed operation. In GM-Ms employing special squirrel-cage rotors and brushless structures, vibration suppression faces multiple challenges: First, the complex topology of the nested loops in the special squirrel-cage rotor generates a rich spectrum of spatial harmonics due to its magnetic field modulation, making it difficult to accurately analyze their interaction with the stator's dual winding magnetic fields. This makes it impossible to accurately calculate the order, frequency, and amplitude of the main electromagnetic force waves. Second, in variable-speed operation, the current frequencies of the stator power windings and stator control windings dynamically change with the rotational speed, resulting in inconsistent main excitation force frequencies and complex coupling relationships with mechanical structure modes. This renders traditional vibration suppression design methods based on fixed frequency bands ineffective. Therefore, for variable speed generator sets, improvements are needed in both the motor body structure and vibration suppression methods. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention proposes a single-unit variable-speed compressed air energy storage power station and its electromagnetic vibration suppression method. Regarding the motor body, this invention employs a variable-speed generator-motor with a special squirrel-cage rotor structure to replace the traditional wound-rotor motor, fundamentally eliminating the reliability issues caused by brushes and slip rings. In terms of vibration suppression, this invention starts from the magnetic field distribution of the generator-motor, analyzes the static and dynamic eccentricities of the squirrel-cage rotor, derives the vibration frequency components related to the rotational speed, and embeds an electromagnetic vibration observer and a vibration negative feedback closed-loop control architecture into the excitation control system. It actively injects counter-currents to form a canceling magnetic field in the air gap to suppress vibration, adapting to the variable-speed operation where the vibration frequency is not fixed, providing active vibration suppression over a wide speed range for the unit.

[0007] To achieve the above objectives, the first aspect of the present invention provides a single-unit variable-speed compressed air energy storage power station, comprising a generator motor, a compressor, an expander, an air storage tank, and a partial power converter system; the generator motor is capable of switching between electric mode and generator mode, and is mechanically connected to both the compressor and the expander; the air storage tank is connected to the air circuits of both the compressor and the expander; each generator motor includes a stator power winding, a stator control winding, and a squirrel-cage rotor; the generator motor does not have brushes or slip rings; both the stator power winding and the stator control winding are three-phase symmetrical windings; The three-phase lines of the stator power winding are electrically connected to the power grid; the three-phase lines of the stator control winding are electrically connected to the AC side of the partial power converter system, and the other side of the partial power converter system is electrically connected to the power grid, for providing three-phase AC power with adjustable frequency and amplitude to the stator control winding through PWM modulation, so that the speed of the generator motor can be continuously and smoothly adjusted within a preset range; in the electric mode, the generator motor drives the compressor to compress air and store it in the air storage tank; in the generator mode, the generator motor is driven by the expander to convert the mechanical energy released by the compressed air into electrical energy and feed it back to the power grid through the stator power winding.

[0008] Furthermore, the ends of the cage windings of the cage rotor are connected in a preset manner, and the cage windings are connected in series in pairs to form multiple independent circuits; the core structure of the cage rotor is the same as that of the squirrel cage rotor.

[0009] Furthermore, the partial power converter system includes a generator-side converter, a DC link, and a grid-side converter. The AC side of the generator-side converter is electrically connected to the three-phase line of the stator control winding, and the AC side of the grid-side converter is electrically connected to the grid. The other side of the generator-side converter and the other side of the grid-side converter are connected back-to-back via the DC link.

[0010] Furthermore, the single-unit variable-speed compressed air energy storage power station also includes a heat exchanger, a heat collection tank, and a cold collection tank. The compression heat of the compressor is stored in the heat collection tank via the heat exchanger. Before the expander performs work, the compressed air is heated by the heat storage medium in the heat collection tank via the heat exchanger.

[0011] A second aspect of the present invention provides a method for suppressing electromagnetic vibration in a single-unit variable-speed compressed air energy storage power station, comprising the following steps: Step 1: Analyze and obtain the magnetic field distribution of the generator motor. The magnetic field distribution is composed of the superposition of magnetic field components generated by the stator power winding and the stator control winding in the air gap. Step 2: Based on the static and dynamic eccentricity of the cage rotor, obtain the air gap length caused by the eccentricity of the generator motor. Substitute the magnetic field distribution and the air gap length into the air gap magnetic flux density model of the generator motor, and obtain the vibration frequency components of the generator motor through harmonic analysis. Step 3: Embed an electromagnetic vibration observer in the excitation control system of the partial power converter system and construct a vibration negative feedback closed-loop control architecture. The electromagnetic vibration observer continuously monitors the current and frequency signals in the stator power winding and the stator control winding, and dynamically calculates the real-time distribution characteristics of the air gap magnetic field of the generator motor. Step 4: Based on the real-time distribution characteristics of the air gap magnetic field, the excitation control system uses harmonic analysis to obtain the corresponding amplitude and phase characteristics for the vibration frequency components. Based on the amplitude and phase characteristics, it generates a corresponding compensation current in real time, which is injected into the generator motor through the partial power converter system. This forms a canceling magnetic field in the air gap that is equal in amplitude and opposite in phase to the original vibration electromagnetic force, thereby suppressing the vibration of the generator motor.

[0012] Further, in step 1, the net flux density in the air gap is calculated according to the following formula: In the formula: B is the net flux density in the air gap; B1 and B2 are the amplitudes of the first magnetic field component and the second magnetic field component, respectively; ω1 and ω2 are the frequencies of the power supplies corresponding to the stator power winding and the stator control winding, respectively; p1 and p2 are the number of pole pairs of the stator power winding and the stator control winding, respectively; θ is the mechanical angle of the air gap circumference; t is time; φ1 and φ2 are the phase angles of the first magnetic field component and the second magnetic field component, respectively.

[0013] Furthermore, in step 2, the air gap length caused by the eccentricity is calculated according to the following formula: Where: g is the air gap length caused by the eccentricity; g0 is the average air gap length; g s and g d θ represents the amplitude of the eccentric component corresponding to the static eccentricity and the dynamic eccentricity, respectively; θ is the mechanical angle of the air gap circumference; t is time; ω r φ is the rotor angular velocity; α is the angle relative to the stator reference axis; s and φ d These are the angles of the static eccentricity and the dynamic eccentricity relative to the stator reference axis, respectively.

[0014] Furthermore, in step 2, the vibration frequency component of the generator motor obtained by superimposing the magnetic field distribution and the eccentricity includes ω. r , ω1-ω2 and ω1-ω2±ω r Three vibration frequency components; wherein the ω1-ω2 frequency component is caused by the air gap setting and the eccentricity.

[0015] Furthermore, in step 3, the electromagnetic vibration observer and the vibration negative feedback closed-loop control architecture are embedded in the excitation control system of the generator motor, and the excitation control system regulates the current of the stator control winding through the partial power converter system.

[0016] Furthermore, in step 4, the compensation current is injected into the excitation circuit or torque current channel of the stator control winding through the power converter of the partial power converter system in a reverse superposition manner; the canceling magnetic field is used to cancel the vibration frequency components caused by the spatial harmonics of the magnetic field distribution and the eccentricity.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) Elimination of brushes and slip rings. This invention uses a special cage rotor to replace the traditional wound rotor, avoiding electrical faults caused by poor contact, wear, or oxidation of brushes and slip rings, reducing maintenance workload, and improving the overall reliability of the system.

[0018] 2) Adaptable to variable speed operation. The generator motor achieves continuous and smooth speed adjustment within a preset range through the control of the partial power converter system, and can flexibly switch between electric mode and generator mode, adapting to the fluctuations of renewable energy power generation and improving the energy utilization rate of compressed air.

[0019] 3) Vibration suppression is adaptive across all operating conditions. The vibration suppression method proposed in this invention accurately characterizes the combined magnetic field generated by the superposition of the two stator magnetic fields of the generator motor, as well as the air gap unevenness caused by the static and dynamic eccentricity of the squirrel-cage rotor, obtaining a result including ω r , ω1-ω2 and ω1-ω2±ω r The key vibration frequency components; by using an electromagnetic vibration observer to monitor the current and frequency signals of the two sets of windings in real time, extracting vibration spectrum characteristics and generating compensation current in real time, it can adapt to the characteristics of the vibration frequency dynamically changing with the rotational speed under variable speed conditions, overcome the shortcomings of traditional vibration suppression methods based on fixed frequency bands, and realize full-condition vibration control from structural optimization to active suppression.

[0020] 4) High system efficiency. By combining heat recovery technology, the compression heat of the compressor is recovered and the compressed air is reheated before the expander does work, reducing dependence on fossil fuels and further improving system efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the principle of the single-unit variable-speed compressed air energy storage power station of the present invention. Figure 2 This is a schematic diagram of the generator motor with a special cage rotor structure in the single-unit variable speed compressed air energy storage power station of the present invention; Figure 3 This is a schematic diagram of the magnetic field distribution of the generator motor in the single-unit variable speed compressed air energy storage power station of the present invention; Figure 4 This is a schematic diagram showing the stator and rotor eccentricity of the generator motor in the single-unit variable speed compressed air energy storage power station of the present invention; Figure 5 This is a magnetic field spectrum analysis diagram of the generator motor in the single-unit variable speed compressed air energy storage power station of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to the embodiments described. First, the specific implementation of the single-unit variable-speed compressed air energy storage power station of the present invention will be described, and then the specific implementation of the electromagnetic vibration suppression method of the single-unit variable-speed compressed air energy storage power station will be described.

[0023] The single-unit variable-speed compressed air energy storage power station of this invention includes a generator motor, a compressor, an expander, an air storage tank, and a partial power converter system. A schematic diagram of the overall principle of the compressed air energy storage power station is shown below. Figure 1 As shown, its working principle is as follows: In the electric mode of the generator motor, the generator motor operates as a motor, absorbs electrical energy from the power grid, and drives the compressor through a clutchable gearbox to compress air and store it in the air storage tank; in the generator mode of the generator motor, the generator motor operates as a generator, and is driven to rotate by the expander through the clutchable gearbox, converting the mechanical energy released by the compressed air into electrical energy and feeding it back to the power grid.

[0024] Each of the aforementioned generator motors includes a stator power winding, a stator control winding, and a squirrel-cage rotor. A schematic diagram of the cross-sectional structure of the generator motor is shown below. Figure 2As shown. The squirrel-cage rotor is located at the center of the generator motor, and the stator 101 is disposed radially outside the squirrel-cage rotor 102, with an air gap formed between the inner circle of the stator and the outer circle of the squirrel-cage rotor. The stator is provided with power-side terminals 104 and control-side terminals 103, which respectively lead out the three-phase lines of the stator power winding and the three-phase lines of the stator control winding. The generator motor does not have brushes or slip rings.

[0025] The ends of the squirrel-cage windings of the squirrel-cage rotor are connected in a predetermined manner, with each squirrel-cage winding connected in pairs to form multiple independent loops. The core structure of the squirrel-cage rotor is the same as that of a conventional squirrel-cage rotor, resulting in a similar manufacturing process that is simple, robust, and durable. Compared to the squirrel-cage rotor of a conventional induction motor, the end connection method of the squirrel-cage rotor windings in the generator-motor of this invention differs significantly. This end connection method enables coupling between the two sets of stator windings and the squirrel-cage rotor, which is key to realizing the magnetic field modulation function and variable speed operation of the generator-motor. During operation, the induced current in the squirrel-cage windings generates a rotating air gap magnetic field in the air gap. This rotating air gap magnetic field remains relatively stationary with the stator magnetic field generated by the stator power winding and the stator control winding, thereby completing the electromechanical energy conversion of the generator-motor.

[0026] Both the stator power winding and the stator control winding are three-phase symmetrical windings. The three-phase lines of the stator power winding are directly connected to the power grid, serving as the main power transmission channel for the generator motor. The three-phase lines of the stator control winding are connected to the AC side of the partial power converter system, and the other side of the partial power converter system is connected to the power grid. The partial power converter system adopts a three-phase full-bridge AC-DC-AC bidirectional converter structure, specifically including a generator-side converter, a DC link, and a grid-side converter. The AC side of the generator-side converter is connected to the three-phase lines of the stator control winding, and the AC side of the grid-side converter is connected to the power grid. The other side of the generator-side converter and the other side of the grid-side converter are connected back-to-back via the DC link. The partial power converter system provides three-phase AC power with adjustable frequency and amplitude to the stator control winding through PWM modulation, thereby adjusting the magnetic field generated by the stator control winding and continuously and smoothly adjusting the speed of the generator motor within a preset range.

[0027] The single-unit variable-speed compressed air energy storage power station may further include a heat exchanger, a heat collection tank, and a cold collection tank. The heat exchanger is connected to the compressor, the expander, the heat collection tank, and the cold collection tank via pipelines. In the electric mode of the generator motor, the air is compressed by the compressor and its temperature rises. The high-temperature compressed air from the compressor outlet exchanges heat with cold water through the heat exchanger. The cooled compressed air is stored in the air storage tank, and the heated hot water is stored in the heat collection tank. In the generator motor's power generation mode, the compressed air released from the air storage tank is heated by the hot water in the heat collection tank through the heat exchanger and then drives the expander to do work. The cooled water after heat exchange enters the cold collection tank.

[0028] Based on the structure and working principle of the above-mentioned single-unit variable speed compressed air energy storage power station, the present invention further provides an electromagnetic vibration suppression method, including steps 1 to 4, which are described below.

[0029] Step 1: Analyze and calculate the magnetic field distribution of the generator motor. Specifically, the stator power winding and the stator control winding generate two fundamental magnetic field components in the air gap. A schematic diagram of the magnetic field distribution of the generator motor is shown below. Figure 3 As shown in the figure, the magnetic field distribution of the generator motor is given when the number of pole pairs of the stator power winding p1=1 and the number of pole pairs of the stator control winding p2=3. The first magnetic field component has 2p1 poles and its average absolute flux density rotates at frequency ω1, while the second magnetic field component has 2p2 poles and its flux density rotates at frequency ω2. The net flux density in the air gap is essentially the superposition of the first and second magnetic field components, and can be expressed as a function of time and spatial angle. The net flux density in the air gap is calculated according to formula (1): (1) In the formula: B is the net flux density in the air gap; B1 and B2 are the amplitudes of the first and second magnetic field components, respectively; ω1 and ω2 are the frequencies of the power supplies corresponding to the stator power winding and the stator control winding, respectively; p1 and p2 are the number of pole pairs of the stator power winding and the stator control winding, respectively; θ is the mechanical angle of the air gap circumference; t is time; φ1 and φ2 are the phase angles of the first and second magnetic field components, respectively. The variable speed generator-motor with the special squirrel-cage rotor structure is a special type of induction motor. The theoretical analysis of its vibration modes can be derived by referring to the vibration theory of induction motors. The tension applied by the magnetic field is calculated using the above method, thereby determining the displacement of the iron core. The expression for the vibration components provides a method for changing key parameters to reduce vibration during the design of the generator-motor.

[0030] Step 2: Analyze the vibration of the generator-motor considering the eccentricity of the squirrel-cage rotor. Specifically, due to the interaction between the two stator magnetic fields of the generator-motor, in addition to the vibration modes observed in an equivalent induction motor, the eccentricity of the squirrel-cage rotor and the stator may inherently introduce additional magnetic flux components, the number of which differs from the number of poles of the stator windings. This step considers two types of eccentricity: the static eccentricity caused by the offset between the stator shaft center and the central axis of the squirrel-cage rotor shaft, and the dynamic eccentricity caused by the offset between the central axis of the squirrel core and the central axis of the rotor shaft. Schematic diagrams of the static and dynamic eccentricities are shown below. Figure 4 As shown, in the Figure 4 In the diagram, O represents the axis of the stator; O' represents the central axis of the rotor shaft of the squirrel-cage rotor; x and y are the stator reference coordinate axes with O as the origin; x' and y' are the rotor reference coordinate axes with O' as the origin; r represents the amplitude of the eccentric component corresponding to the static eccentricity, i.e., g. s δ(α) represents the value of the air gap length g caused by the eccentricity in the direction of angle α; α is consistent with the angle relative to the stator reference axis in formula (2); γ represents the angle of the static eccentricity relative to the stator reference axis, that is, the angle of φ. s The air gap length caused by the eccentricity is calculated according to formula (2): (2) Where: g is the air gap length caused by the eccentricity; g0 is the average air gap length; g s and g d θ represents the amplitude of the eccentric component corresponding to the static eccentricity and the dynamic eccentricity, respectively; θ is the mechanical angle of the air gap circumference; t is time; ω r φ is the rotor angular velocity; α is the angle relative to the stator reference axis; s and φ d These are the angles of the static eccentricity and the dynamic eccentricity relative to the stator reference axis, respectively.

[0031] From magnetization current density J m The magnetic flux density in the air gap caused by (θ,t) can be derived from Ampere's law, and the magnetic flux density is calculated according to formula (3): (3) In the formula: J m (θ,t) represents the magnetizing current density; θ is the mechanical angle of the air gap circumference; t is time; D a The equivalent diameter of the air gap of the generator motor is given; the magnetomotive force drop of the iron core portion passing through the magnetic circuit is ignored.

[0032] The reciprocal of the air gap function in formula (3) can be expressed as a Fourier series as formula (4): (4) In the formula: d s1 and d d1 These are the eccentricity coefficients corresponding to the static eccentricity and the dynamic eccentricity, respectively; given that these coefficients are typically very small, the d... s1 and the d d1 They can be approximated as g respectively s / g0 and g d / g0.

[0033] By analyzing the above formulas, substituting the net flux density described in formula (1) and the air gap length caused by eccentricity described in formula (2) into the magnetic flux density expression described in formula (3), and combining the Fourier series expansion of the reciprocal of the air gap function described in formula (4), and performing harmonic analysis on the magnetic flux density from a temporal and spatial perspective, it can be obtained that the most important vibration frequency component in the vibration spectrum of the generator motor is ω. r , ω1-ω2 and ω1-ω2±ω r Three vibration frequency components. Among them, the ω1-ω2 frequency component is caused by the air gap setting and the eccentricity; the vibration of the generator motor is generated by the superposition of the magnetic field distribution and the eccentricity. The following conclusions can be drawn from this: First, the unbalanced magnetic pull of the generator motor is related to the rotor radius of the squirrel-cage rotor, the air gap length, and the fundamental magnetomotive force amplitudes of the stator power winding and the stator control winding; Second, when the number of pole pairs of the stator power winding and the stator control winding are different, the vibration response of the squirrel-cage rotor is composed of two different frequency harmonic waves superimposed. Its frequency is related to the rotor radius, the air gap length, the fundamental amplitudes of the stator power winding and the stator control winding, and the axial length of the squirrel-cage rotor. The mode corresponding to each natural frequency is only related to the initial phase difference between the two synthetic magnetomotive forces of the stator power winding and the stator control winding; Third, the vibration amplitude of the squirrel-cage rotor is related to the initial conditions. When the initial conditions are small, the vibration amplitude is small. When the initial conditions increase, the vibration amplitude also increases. However, the natural frequency of the squirrel-cage rotor is independent of the initial conditions.

[0034] Step 3: Based on the magnetic field distribution obtained in Step 1 and the vibration frequency components obtained in Step 2, an electromagnetic vibration observer is embedded in the excitation control system of the partial power converter system, and a vibration negative feedback closed-loop control architecture is constructed. The electromagnetic vibration observer continuously monitors the current and frequency signals in the stator power winding and the stator control winding, and dynamically calculates the real-time distribution characteristics of the air gap magnetic field based on the current and frequency signals. The air gap magnetic field distribution and spectrum of the generator motor under different operating conditions can be obtained by finite element simulation or online measurement. The magnetic field spectrum analysis diagram is shown below. Figure 5 As shown, the main pole pair components and their magnetic flux density amplitudes can be clearly identified from the magnetic field spectrum analysis diagram.

[0035] Step 4: Based on the real-time distribution characteristics of the air gap magnetic field obtained in Step 3, the excitation control system uses a fast harmonic analysis algorithm to accurately separate the vibration frequency components and their amplitude and phase characteristics from the current signal and the frequency signal for the vibration frequency components obtained in Step 2. Based on this, the excitation control system, according to the extracted vibration spectrum characteristics and combined with the electromagnetic parameters of the generator motor, real-time load and speed information, and operating conditions, generates a dynamic compensation current command with corresponding amplitude, phase, and frequency characteristics in real time. The compensation current corresponding to the dynamic compensation current command is injected into the excitation circuit or torque current channel of the stator control winding through the power converter of the partial power converter system in a reverse superposition manner, forming a canceling magnetic field in the air gap with the same amplitude but opposite phase to the original vibration electromagnetic force. This achieves online identification and active suppression of key vibration components, improving the operational stability of the generator motor over a wide speed range.

[0036] As a further optimization of the electromagnetic vibration suppression method described in this invention, based on steps 1 to 4, the generator motor can also weaken the harmonic source from a structural perspective: according to the magnetic field distribution obtained in step 1 and the vibration frequency components obtained in step 2, the cage topology of the cage rotor and the design parameters of the stator power winding and the stator control winding are optimized to weaken the spatial harmonics and main electromagnetic force wave components generated by the magnetic field modulation effect at the source; the active injection of the compensation current in step 4 is implemented in conjunction with the above-mentioned structural optimization method to achieve full-condition vibration control from structural optimization to active suppression.

[0037] As a specific embodiment of the present invention, the single-unit variable-speed compressed air energy storage power station of this embodiment adopts a 10MW-class doubly-fed variable-speed generator motor as the core energy conversion unit. The number of pole pairs of the stator power winding of the generator motor is p1=1, and the number of pole pairs of the stator control winding is p2=3. The corresponding magnetic field distribution of the generator motor is as follows: Figure 3 As shown. In the steady-state synchronous operation mode of the generator motor, the rotor angular velocity ω corresponding to the rated operating speed of the generator motor is... r The frequency ω1 of the stator power winding and the frequency ω2 of the stator control winding satisfy ω r The relationship is (ω1+ω2) / (p1+p2). The vibration spectrum of the generator motor includes ω. r , ω1-ω2 and ω1-ω2±ω r Three characteristic frequency components. The electromagnetic vibration observer collects the current signals and frequency signals of the two sets of stator windings and the rotational speed signal of the squirrel-cage rotor in real time. Combined with the magnetic field and air gap models described in formulas (1) to (4), the vibration frequency components and their amplitude and phase characteristics are calculated. The excitation control system generates a compensation current command with the same amplitude and opposite phase as the vibration frequency components, which is injected into the stator control winding to cancel the corresponding vibration components. Those skilled in the art can adjust the specific calculation parameters of the compensation current command according to the actual capacity, number of pole pairs and operating conditions of the generator motor, without departing from the principle of the present invention.

[0038] As an extended embodiment of the present invention, the electromagnetic vibration observer and the vibration negative feedback closed-loop control architecture can be integrated with other protection systems such as the state monitoring system, temperature monitoring system, and overload relay protection system of the generator motor to form a comprehensive protection and control scheme for the generator motor unit; the injection method of the compensation current is not limited to the excitation circuit or the torque current channel of the stator control winding, and other injection positions can be selected according to the specific topology of the partial power converter system of the generator motor.

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A single-unit variable-speed compressed air energy storage power station, characterized in that, The single-unit variable-speed compressed air energy storage power station includes a generator motor, a compressor, an expander, an air storage tank, and a partial power converter system. The generator motor can switch between electric and generator modes. The generator motor is mechanically connected to both the compressor and the expander. The air storage tank is connected to the air circuits of both the compressor and the expander. Each generator motor includes a stator power winding, a stator control winding, and a squirrel-cage rotor. The generator motor does not have brushes or slip rings. Both the stator power winding and the stator control winding are three-phase symmetrical windings. The three-phase lines of the stator power winding are electrically connected to the power grid. The three-phase lines of the stator control winding are electrically connected to the AC side of the partial power converter system, and the other side of the partial power converter system is electrically connected to the power grid. This is used to provide three-phase AC power with adjustable frequency and amplitude to the stator control winding through PWM modulation, so that the speed of the generator motor can be continuously and smoothly adjusted within a preset range. In the electric mode, the generator motor drives the compressor to compress air and store it in the air storage tank. In the generator mode, the generator motor is driven by the expander to convert the mechanical energy released by the compressed air into electrical energy and feed it back to the power grid through the stator power winding.

2. The single-unit variable-speed compressed air energy storage power station according to claim 1, characterized in that, The ends of the cage windings of the cage rotor are connected in a preset manner, and the cage windings are connected in series in pairs to form multiple independent circuits; the core structure of the cage rotor is the same as that of the squirrel cage rotor.

3. The single-unit variable-speed compressed air energy storage power station according to claim 1, characterized in that, The partial power converter system includes a generator-side converter, a DC link, and a grid-side converter. The AC side of the generator-side converter is electrically connected to the three-phase line of the stator control winding. The AC side of the grid-side converter is electrically connected to the grid. The other side of the generator-side converter and the other side of the grid-side converter are connected back-to-back via the DC link.

4. The single-unit variable-speed compressed air energy storage power station according to claim 1, characterized in that, The single-unit variable-speed compressed air energy storage power station also includes a heat exchanger, a heat collection tank, and a cold collection tank. The heat of compression of the compressor is stored in the heat collection tank via the heat exchanger. Before the expander performs work, the compressed air is heated by the heat storage medium in the heat collection tank via the heat exchanger.

5. A method for suppressing electromagnetic vibration in a single-unit variable-speed compressed air energy storage power station as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Analyze and obtain the magnetic field distribution of the generator motor. The magnetic field distribution is composed of the superposition of magnetic field components generated by the stator power winding and the stator control winding in the air gap. Step 2: Based on the static and dynamic eccentricity of the cage rotor, obtain the air gap length caused by the eccentricity of the generator motor. Substitute the magnetic field distribution and the air gap length into the air gap magnetic flux density model of the generator motor, and obtain the vibration frequency components of the generator motor through harmonic analysis. Step 3: Embed an electromagnetic vibration observer in the excitation control system of the partial power converter system and construct a vibration negative feedback closed-loop control architecture. The electromagnetic vibration observer continuously monitors the current and frequency signals in the stator power winding and the stator control winding, and dynamically calculates the real-time distribution characteristics of the air gap magnetic field of the generator motor. Step 4: Based on the real-time distribution characteristics of the air gap magnetic field, the excitation control system uses harmonic analysis to obtain the corresponding amplitude and phase characteristics for the vibration frequency components. Based on the amplitude and phase characteristics, it generates a corresponding compensation current in real time, which is injected into the generator motor through the partial power converter system. This forms a canceling magnetic field in the air gap that is equal in amplitude and opposite in phase to the original vibration electromagnetic force, thereby suppressing the vibration of the generator motor.

6. The electromagnetic vibration suppression method for a single-unit variable-speed compressed air energy storage power station according to claim 5, characterized in that, In step 1, the net flux density in the air gap is calculated according to the following formula: In the formula: B is the net flux density in the air gap; B1 and B2 are the amplitudes of the first magnetic field component and the second magnetic field component, respectively; ω1 and ω2 are the frequencies of the power supplies corresponding to the stator power winding and the stator control winding, respectively; p1 and p2 are the number of pole pairs of the stator power winding and the stator control winding, respectively; θ is the mechanical angle of the air gap circumference; t is time; φ1 and φ2 are the phase angles of the first magnetic field component and the second magnetic field component, respectively.

7. The electromagnetic vibration suppression method for a single-unit variable-speed compressed air energy storage power station according to claim 5, characterized in that, In step 2, the air gap length caused by the eccentricity is calculated using the following formula: Where: g is the air gap length caused by the eccentricity; g0 is the average air gap length; g s and g d θ represents the amplitude of the eccentric component corresponding to the static eccentricity and the dynamic eccentricity, respectively; θ is the mechanical angle of the air gap circumference; t is time; ω r φ is the rotor angular velocity; α is the angle relative to the stator reference axis; s and φ d These are the angles of the static eccentricity and the dynamic eccentricity relative to the stator reference axis, respectively.

8. The electromagnetic vibration suppression method for a single-unit variable-speed compressed air energy storage power station according to claim 5, characterized in that, In step 2, the vibration frequency components of the generator motor, obtained by superimposing the magnetic field distribution and the eccentricity, include ω. r , ω1-ω2 and ω1-ω2±ω r Three vibration frequency components; wherein the ω1-ω2 frequency component is caused by the air gap setting and the eccentricity.

9. The electromagnetic vibration suppression method for a single-unit variable-speed compressed air energy storage power station according to claim 5, characterized in that, In step 3, the electromagnetic vibration observer and the vibration negative feedback closed-loop control architecture are embedded in the excitation control system of the generator motor. The excitation control system regulates the current of the stator control winding through the partial power converter system.

10. The electromagnetic vibration suppression method for a single-unit variable-speed compressed air energy storage power station according to claim 5, characterized in that, In step 4, the compensation current is injected into the excitation circuit or torque current channel of the stator control winding through the power converter of the partial power converter system in a reverse superposition manner; the canceling magnetic field is used to cancel the vibration frequency components caused by the spatial harmonics of the magnetic field distribution and the eccentricity.

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