Virtual synchronous machine control method of energy storage system and flywheel energy storage system
By adaptively adjusting virtual inertia, damping coefficient, and virtual impedance, the problem of unbalanced frequency stability and active power response speed in traditional virtual synchronous machine control is solved, thereby improving the dynamic response performance of the energy storage system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA LVFA INVESTMENT GRP CO LTD
- Filing Date
- 2026-02-13
- Publication Date
- 2026-05-29
AI Technical Summary
In traditional virtual synchronous machine control strategies, the virtual inertia and damping coefficient are fixed, which cannot guarantee the optimal balance between frequency stability and active power response speed of the energy storage system, resulting in insufficient dynamic performance of frequency change rate and frequency difference.
By adaptively adjusting the values of virtual inertia, damping coefficient, and virtual impedance, and dynamically adjusting the control parameters of the virtual synchronizer based on the sign and absolute value of the rate of change of angular frequency and the angular frequency deviation, frequency stability and active power response speed are optimized.
It effectively suppresses the rate of frequency change and frequency difference, improves the dynamic response performance of the system, ensures rapid response of active power, and improves the frequency stability and inertia characteristics of new power systems.
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Figure CN122118852A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of virtual synchronous generator control technology, and in particular to a virtual synchronous generator control method for an energy storage system and a flywheel energy storage system. Background Technology
[0002] In response to the national dual-carbon goals and to address the energy shortages and environmental degradation caused by the use of traditional fossil fuels, building a new power system has become an inevitable trend in my country's power system development. However, because the new power system has a high proportion of renewable energy and power electronic equipment, it typically exhibits characteristics of "low inertia and weak damping," posing a severe challenge to frequency stability, making energy storage increasingly crucial. Flywheel energy storage, with its fast response and long lifespan, is well-suited for participating in grid frequency regulation.
[0003] To improve the inertia and damping characteristics of new power systems, Virtual Synchronous Machine (VSG) control technology can be applied to the grid-side converter of flywheel energy storage systems. This technology simulates the rotor motion equation of a synchronous generator in the converter's control algorithm to provide virtual inertia support and damping for the system, thus helping to improve the system's frequency stability. Under the VSG control strategy, the active power and frequency output characteristics are closely related to the virtual inertia J and the damping coefficient D. Traditional VSG control uses fixed virtual inertia J and damping coefficient D, which cannot guarantee optimal dynamic performance; although the two parameters, virtual inertia J and damping coefficient D, adaptively improve the rate of frequency change and frequency difference during transient processes, they slow down the response of active power. Summary of the Invention
[0004] The purpose of this application is to provide a virtual synchronous machine control method and a flywheel energy storage system for an energy storage system, which can effectively solve at least one of the technical problems mentioned in the prior art.
[0005] One aspect of this application provides a virtual synchronous machine control method for an energy storage system. The method includes: acquiring the current angular frequency change rate and current angular frequency deviation of the virtual synchronous machine; adaptively adjusting the values of the virtual inertia, damping coefficient, and virtual impedance of the virtual synchronous machine based on the current angular frequency change rate and the current angular frequency deviation; and inputting the adjusted values of the virtual inertia, damping coefficient, and virtual impedance into the virtual synchronous machine control loop to control the grid-side converter of the energy storage system.
[0006] Furthermore, the virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: when the current angular frequency change rate and the current angular frequency deviation have the same sign, the virtual inertia and the damping coefficient are increased, and the virtual impedance is decreased; when the current angular frequency change rate and the current angular frequency deviation have opposite signs, the virtual inertia is decreased, the damping coefficient is increased, and the virtual impedance is decreased.
[0007] Further, the adaptive adjustment of the virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer based on the current angular frequency change rate and the current angular frequency deviation includes: when the absolute value of the current angular frequency change rate is less than or equal to a predetermined first adjustment threshold, maintaining the initial value of the virtual inertia unchanged; when the absolute value of the current angular frequency change rate is greater than the first adjustment threshold, continuing to determine the magnitude of the product of the current angular frequency change rate and the current angular frequency deviation; when the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the product of the current angular frequency change rate and the current angular frequency deviation is greater than 0, increasing the value of the virtual inertia; and when the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the product of the current angular frequency change rate and the current angular frequency deviation is less than or equal to 0, decreasing the value of the virtual inertia.
[0008] Further, increasing the value of the virtual inertia includes: adding a first predetermined value to the initial value of the virtual inertia, the first predetermined value being equal to the product of a predetermined first virtual inertia adjustment coefficient and the absolute value of the current angular frequency change rate; decreasing the value of the virtual inertia includes: decreasing the value of the virtual inertia by a second predetermined value to the initial value of the virtual inertia, the second predetermined value being equal to the product of a predetermined second virtual inertia adjustment coefficient and the absolute value of the current angular frequency change rate.
[0009] Furthermore, the virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: when the absolute value of the current angular frequency deviation is less than or equal to a predetermined second adjustment threshold, the value of the damping coefficient is kept constant at the initial value of the damping coefficient; when the absolute value of the current angular frequency deviation is greater than the second adjustment threshold, the value of the damping coefficient is increased.
[0010] Furthermore, increasing the value of the damping coefficient includes: adding a third predetermined value to the initial value of the damping coefficient, wherein the third predetermined value is equal to the product of a predetermined damping coefficient adjustment coefficient and the absolute value of the current angular frequency deviation.
[0011] Furthermore, the adaptive adjustment of the virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer based on the current angular frequency change rate and the current angular frequency deviation includes: when the absolute value of the current angular frequency change rate is less than or equal to a predetermined first adjustment threshold or the absolute value of the current angular frequency deviation is less than or equal to a predetermined second adjustment threshold, the virtual impedance value is kept unchanged at the initial virtual impedance value; when the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the absolute value of the current angular frequency deviation is greater than the second adjustment threshold, the virtual impedance value is decreased.
[0012] Further, reducing the value of the virtual impedance includes: reducing the value of the virtual impedance by a fourth predetermined value based on the initial value of the virtual impedance, wherein the fourth predetermined value is equal to the product of a predetermined virtual impedance adjustment coefficient and the absolute value of the current angular frequency deviation.
[0013] Further, obtaining the current angular frequency change rate and current angular frequency deviation of the virtual synchronizer includes: obtaining the current mechanical power, current output power, and angular frequency deviation of the virtual synchronizer at the previous moment; obtaining the current angular frequency change rate of the virtual synchronizer based on the current mechanical power, current output power, and angular frequency deviation at the previous moment, and based on the current value of the virtual inertia and the current value of the damping coefficient; and obtaining the current angular frequency deviation of the virtual synchronizer based on the current angular frequency change rate of the virtual synchronizer.
[0014] Another aspect of this application provides a flywheel energy storage system. The flywheel energy storage system includes a flywheel rotor, a permanent magnet synchronous machine, a back-to-back converter, a DC bus capacitor, an LC filter, an AC power grid, and a control system. The back-to-back converter includes a machine-side converter and a grid-side converter. The DC bus capacitor is located between the machine-side converter and the grid-side converter. The flywheel rotor is used to store and release energy. The energy is transmitted to the AC power grid through the permanent magnet synchronous machine and the back-to-back converter, and filtered by the LC filter. The control system uses the virtual synchronous machine control method of the energy storage system described above to control the grid-side converter.
[0015] This application presents one or more embodiments of a virtual synchronous machine control method and a flywheel energy storage system for energy storage systems. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the topology of a flywheel energy storage system according to an embodiment of this application.
[0017] Figure 2 This is a general flowchart of a virtual synchronous machine control method for an energy storage system according to an embodiment of this application.
[0018] Figure 3 This is a flowchart illustrating a specific example of the virtual synchronous machine control method for the energy storage system of this application.
[0019] Figure 4 This is a schematic diagram of the active power-frequency control loop in a control system according to an embodiment of this application.
[0020] Figure 5 This is a schematic diagram of a virtual impedance control loop in a control system according to an embodiment of this application.
[0021] Figure 6 This is a schematic diagram of a virtual inertia adaptive adjustment module in a control system according to an embodiment of this application.
[0022] Figure 7 This is a schematic diagram of an adaptive damping coefficient adjustment module in a control system according to an embodiment of this application.
[0023] Figure 8 This is a schematic diagram of a virtual impedance adaptive adjustment module in a control system according to an embodiment of this application. Detailed Implementation
[0024] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses consistent with some aspects of this application as detailed in the appended claims.
[0025] The virtual synchronous machine control method and flywheel energy storage system of this application will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the features of the following embodiments and implementations can be combined with each other.
[0026] Figure 1 A schematic diagram of the topology of a flywheel energy storage system 100 according to an embodiment of this application is shown. Figure 1 As shown, a flywheel energy storage system 100 according to one embodiment of this application includes a flywheel rotor 110, a permanent magnet synchronous motor 120, a back-to-back converter, and a DC bus capacitor C. dc LC filter 150 and AC grid 160. The back-to-back converters include a generator-side converter 130 and a grid-side converter 140, and a DC bus capacitor C. dc Located between the machine-side converter 130 and the grid-side converter 140. The flywheel rotor 110 is used to store and release energy, which is then transferred to the AC grid 160 through the permanent magnet synchronous motor 120 and the back-to-back converter, and filtered by the LC filter 150.
[0027] The generator-side converter 130 adopts a control strategy of voltage outer loop and current inner loop to maintain DC bus voltage stability, while the grid-side converter 140 adopts a VSG (virtual synchronous machine) control strategy.
[0028] The active-frequency control of the virtual synchronous machine simulates the rotor motion equation of the synchronous motor, and its mathematical model is as follows: (1) in, Let P be the rate of change of the VSG's angular frequency, J and D be the VSG's virtual inertia and damping coefficient, respectively, ω and ω0 be the VSG's actual and reference angular frequencies, respectively. m P e and P ref These represent the mechanical power, output power, and reference power of the VSG, respectively, k ω This is the active power droop coefficient.
[0029] From the above equation, the transfer function of the VSG active power loop can be derived as follows: (2) Where E and U are the internal potential of the virtual synchronous machine and the grid connection point voltage, respectively, and X is the equivalent impedance, including the line impedance and the virtual impedance Xv of the virtual synchronous machine.
[0030] The natural angular frequency ω of the flywheel energy storage system 100 can be obtained from equation (2). n Damping ratio for: (3) When the flywheel energy storage system 100 is in an underdamped state, the overshoot σ% and settling time t of the flywheel energy storage system 100 are... s as follows: (4) Therefore, it can be seen that as the virtual inertia J increases, the natural oscillation angular frequency ω... n Damping ratio All decrease, overshoot σ% increases, and settling time t s The damping coefficient D increases; as the damping coefficient D increases, the natural oscillation angular frequency ω increases. n The only constant is the damping ratio. Increase, overshoot σ% decreases, settling time t s Shortens; as the equivalent impedance X increases, the natural oscillation angular frequency ω... n Reduce, damping ratio As the line impedance increases, the overshoot σ% decreases. Since the line impedance is a fixed value, the increase or decrease of the equivalent impedance X refers to the increase or decrease of the virtual impedance Xv of the virtual synchronizer.
[0031] Meanwhile, from equation (1), the influence of the virtual inertia J and damping coefficient D of the VSG on the frequency output characteristics can be derived as follows: (5) Among them, T m T e T D These are the mechanical torque, electromagnetic torque, and damping torque of the virtual synchronous machine, respectively.
[0032] As shown in the above equation, increasing the virtual inertia J can increase the rate of change of angular frequency. Decreasing or increasing the damping coefficient D can reduce the angular frequency deviation Δω.
[0033] From the above derivation, the rate of change of angular frequency can be determined. The influence of angular frequency deviation Δω on the virtual inertia J, damping coefficient D, and virtual impedance Xv of the virtual synchronizer.
[0034] Based on the above rate of change of angular frequency The derivation of the influence of angular frequency deviation Δω on the virtual inertia J, damping coefficient D, and virtual impedance Xv of the virtual synchronizer allows us to determine that the adaptive principle for these three parameters is: [the principle is based on the current rate of change of angular frequency]. If the signs of the current angular frequency deviation Δω are the same, it indicates that the frequency is deviating further from the reference value. In this case, the virtual inertia J and damping coefficient D should be increased to reduce the frequency change rate and frequency difference. At the same time, the virtual impedance Xv should be decreased to accelerate the active response speed. If the signs of the current angular frequency change rate and the current angular frequency deviation Δω are opposite, it indicates that the frequency needs to recover to the reference value. In this case, the virtual inertia J should be decreased to accelerate the frequency recovery. At the same time, the damping coefficient D should be appropriately increased to reduce the frequency difference. In order to prevent the flywheel energy storage system 100 from becoming overdamped and thus slowing down the response speed, the virtual impedance Xv can be appropriately decreased.
[0035] Table 1 below reveals the adaptive principle of the three parameters of the virtual synchronous machine in this application: virtual inertia J, damping coefficient D, and virtual impedance Xv.
[0036] Table 1 Adaptive Principles of J, D, and Xv Three Parameters Referring to Table 1, in some embodiments, the adaptive control equations for the three parameters of the virtual synchronous machine—virtual inertia J, damping coefficient D, and virtual impedance Xv—can be designed as follows: (6) (7) (8) Among them, J0, D0, X v0 These are the initial values of the virtual inertia, damping coefficient D, and virtual impedance Xv of the virtual synchronizer, respectively; k j1 k j2 These are the automatic adjustment coefficients for the virtual inertia J, referred to as the first virtual inertia adjustment coefficient and the second virtual inertia adjustment coefficient, respectively; k d It is the automatic adjustment coefficient of the damping coefficient D, also known as the damping coefficient adjustment coefficient; k x It is the automatic adjustment coefficient of the virtual impedance Xv, and is called the virtual impedance adjustment coefficient; T1 and T2 are the first adjustment threshold and the second adjustment threshold for starting automatic adjustment, respectively.
[0037] By establishing a mathematical model of a virtual synchronous machine, this paper analyzes the influence of the virtual inertia J, damping coefficient D, and virtual impedance Xv on the active power and frequency output characteristics. Based on this, this application provides a virtual synchronous machine control method for energy storage systems. The method can coordinately adjust the three control parameters of the virtual synchronous machine—virtual inertia J, damping coefficient D, and virtual impedance Xv—according to the rate of change of angular frequency and the angular frequency deviation Δω. This aims to solve the problem of insufficient control freedom in fixed parameter control strategies and the coordinated adaptive control method of virtual inertia J and damping coefficient D, and helps to further improve the dynamic response performance of the virtual synchronous machine.
[0038] Figure 2 A general flowchart of a virtual synchronous machine control method for an energy storage system according to an embodiment of this application is disclosed. Figure 2 As shown, a virtual synchronous machine control method for an energy storage system according to an embodiment of this application may include steps S1 to S3.
[0039] In step S1, the current angular frequency change rate of the virtual synchronizer is obtained. And the current angular frequency deviation Δω.
[0040] In some embodiments, step S1 involves obtaining the current angular frequency change rate of the virtual synchronizer. The current angular frequency deviation Δω can include steps S11 to S13.
[0041] In step S11, the current mechanical power, current output power, and angular frequency deviation Δω of the virtual synchronizer at the previous moment are obtained.
[0042] Based on the reference power, active power droop coefficient, and angular frequency deviation Δω of the virtual synchronizer at the previous moment, the current mechanical power of the virtual synchronizer can be obtained through the above formula (1).
[0043] In step S12, based on the current mechanical power P mThe current output power and the angular frequency deviation Δω of the previous moment, and based on the current value of the virtual inertia J and the current value of the damping coefficient D, can be used to obtain the current angular frequency change rate of the virtual synchronizer through the above equation (1). .
[0044] In step S13, the current angular frequency change rate of the virtual synchronizer obtained in step S12 is determined. This allows us to obtain the current angular frequency deviation Δω of the virtual synchronizer.
[0045] In step S2, the current angular frequency change rate of the virtual synchronizer obtained in step S1 is... The current angular frequency deviation Δω is derived from the values of the virtual inertia J, damping coefficient D, and virtual impedance Xv of the adaptively adjusted virtual synchronizer.
[0046] In step S3, the adjusted values of virtual inertia J, damping coefficient D, and virtual impedance Xv are input into the virtual synchronous machine control loop to control the grid-side converter 140 of the energy storage system.
[0047] The virtual synchronous machine control method for the energy storage system in this application uses the collected angular frequency change rate... The virtual synchronous machine's virtual inertia J, damping coefficient D, and virtual impedance Xv are adjusted in real time using the angular frequency deviation Δω. This effectively suppresses the rate of frequency change and frequency deviation when disturbances occur, while also taking into account the dynamic response speed of active power. It can improve the rate of frequency change and frequency deviation during transient processes without causing the active power response to be too slow, thereby improving the dynamic response of the energy storage system and comprehensively enhancing the dynamic stability and response performance of the power grid when facing disturbances.
[0048] Figure 3 A flowchart illustrating a specific example of the virtual synchronous machine control method for the energy storage system of this application is shown. Figure 3 As shown, in step 301, the current angular frequency change rate of the VSG is collected. And the deviation Δω of the current angular frequency; in step 302, determine the rate of change of the current angular frequency. Whether the absolute value is less than or equal to the predetermined first adjustment threshold T1, i.e., whether... If the judgment result is "yes", then proceed to step S303. At the current angular frequency change rate... The absolute value is greater than the first adjustment threshold T1, that is... If so, proceed to step S304. In step 303, at the current angular frequency change rate... When the absolute value is less than or equal to the first adjustment threshold T1, the value of the virtual inertia J is kept unchanged from the initial value J0 of the virtual inertia. In step 304, the current rate of change of angular frequency is further determined. The magnitude of the product of the current angular frequency deviation Δω, specifically, determines the rate of change of the current angular frequency. Whether the product of the current angular frequency deviation Δω and the current angular frequency is less than or equal to 0, i.e., whether... If the result of the judgment is "yes", proceed to step 305. Otherwise, proceed to step 306. In step 305, the current angular frequency change rate is... The absolute value is greater than the first adjustment threshold and the current angular frequency change rate If the product of the virtual inertia J and the current angular frequency deviation Δω is less than or equal to 0, then the value of the virtual inertia J is decreased. Optionally, the value of the virtual inertia J can be reduced by a second predetermined value based on the initial virtual inertia value J0. The second predetermined value is equal to a predetermined second virtual inertia adjustment coefficient k. j2 With the rate of change of the current angular frequency The product of the absolute values, i.e. In step 306, at the current rate of change of angular frequency... The absolute value is greater than the first adjustment threshold and the current angular frequency change rate If the product of the virtual inertia J and the current angular frequency deviation Δω is greater than 0, then the value of the virtual inertia J is increased. Optionally, the value of the virtual inertia J can be increased by a first predetermined value based on the initial virtual inertia value J0. The first predetermined value is equal to a predetermined first virtual inertia adjustment coefficient k. j1 With the rate of change of the current angular frequency The product of the absolute values, i.e. In step 307, the adaptively adjusted virtual inertia J is output. In step 308, it is determined whether the absolute value of the current angular frequency deviation Δω is less than or equal to the predetermined second adjustment threshold T2, i.e., whether... If the judgment result is "yes", proceed to step S309. Otherwise, proceed to step 310. In step 309, when the absolute value of the current angular frequency deviation Δω is less than or equal to the second adjustment threshold T2, the value of the damping coefficient D is kept unchanged from the initial value D0, i.e., D = D0. In step 310, when the absolute value of the current angular frequency deviation Δω is greater than the second adjustment threshold T2, the value of the damping coefficient D is increased. Optionally, the value of the damping coefficient D can be increased by a third predetermined value based on the initial value D0, and the third predetermined value is equal to a predetermined damping coefficient adjustment coefficient k. d The product of the current angular frequency deviation Δω and the absolute value of the current angular frequency deviation, i.e. In step 311, the adaptively adjusted damping coefficient D is output. In step 312, the current angular frequency change rate is determined. Whether the absolute value of the current angular frequency deviation Δω is less than or equal to the predetermined first adjustment threshold T1 or whether the absolute value of the current angular frequency deviation Δω is less than or equal to the predetermined second adjustment threshold T2, i.e., whether... or If the result of the judgment is "yes", proceed to step 313. Otherwise, proceed to step 314. In step 313, the current angular frequency change rate is... When the absolute value of the current angular frequency deviation Δω is less than or equal to the first adjustment threshold T1, or when the absolute value of the current angular frequency deviation Δω is less than or equal to the second adjustment threshold T2, the virtual impedance Xv is kept constant at the initial virtual impedance value Xv0, i.e., Xv = Xv0. In step 313, at the current angular frequency change rate... When the absolute value of the current angular frequency deviation Δω is greater than the first adjustment threshold T1 and the absolute value of the current angular frequency deviation Δω is greater than the second adjustment threshold T2, the value of the virtual impedance Xv is reduced. Optionally, the value of the virtual impedance Xv can be reduced by a fourth predetermined value based on the initial virtual impedance value Xv0, where the fourth predetermined value is equal to a predetermined virtual impedance adjustment coefficient k. x The product of the current angular frequency deviation Δω and the absolute value of the current angular frequency deviation, i.e. In step 315, the adaptively adjusted virtual impedance Xv is output.
[0049] This application also provides a flywheel energy storage system 100. The flywheel energy storage system 100 includes a control system 170, which can use the virtual synchronous machine control method of the energy storage system described above to control the grid-side converter 140. In the active-frequency outer loop and the virtual impedance Xv control section, a three-parameter adaptive adjustment method of virtual inertia J, damping coefficient D, and virtual impedance Xv is adopted, based on the collected angular frequency change rate. The system uses the angular frequency deviation Δω to adjust three parameters in real time: virtual inertia J, damping coefficient D, and virtual impedance Xv, thereby improving the dynamic response of the energy storage system. The control system 170 employs a voltage outer loop and current inner loop control strategy for the generator-side converter 130 to maintain DC bus voltage stability.
[0050] The following will combine Figures 4 to 8 This paper describes in detail the specific control structure of the control system 170 of this application, which involves the coordinated adaptive adjustment of three parameters: virtual inertia J, damping coefficient D, and virtual impedance Xv.
[0051] Figure 4 A schematic diagram of the active power-frequency (Pf) control loop in a control system 170 according to an embodiment of this application is shown. Figure 4 As shown and referring to the above formula (1), the difference between the reference angular frequency ω0 and the actual angular frequency ω of the VSG is related to the active droop coefficient k. ω Multiply them, and the resulting product is the same as the reference power P. ref The mechanical power P of the VSG is obtained by adding them together. m Mechanical power P m With output power P eThe difference is divided by the reference angular frequency ω0, and the quotient is then subtracted from the product of the difference between the actual angular frequency ω and the reference angular frequency ω0 of the VSG and the damping coefficient D. Then, after integration and division by the virtual inertia J, the angular frequency is obtained, thus transforming the power imbalance into the angular frequency ω.
[0052] Figure 5 A schematic diagram of the virtual impedance Xv control loop in a control system 170 according to an embodiment of this application is shown. (See figure and accompanying diagram.) Figure 1 As shown, the collected grid connection point voltage u abc and current i abc After power calculation by power calculation module 171, active power P and reactive power Q are output. Three-parameter adaptive adjustment module 172 outputs the adjusted virtual inertia J, damping coefficient D, and virtual impedance Xv to the VSG control loop. Active power P, the adjusted virtual inertia J, and damping coefficient D pass through the active-frequency (Pf) loop in virtual synchronizer (VSG) control module 173 to obtain the virtual synchronizer angle θ. Reactive power Q passes through the reactive-voltage (QU) loop in virtual synchronizer (VSG) control module 173 to obtain the virtual synchronizer internal potential E. The virtual synchronizer internal potential E, angle θ, and adjusted virtual impedance Xv pass through virtual impedance control module 174 to obtain the d-axis and q-axis reference voltage u. dref u qref Specifically, such as Figure 4 As shown, the internal potential E and angle θ of the virtual synchronizer are transformed into the internal potentials E on the d and q axes through the abc / dq coordinate transformation module. d E q The output current i of the grid-side converter 140 Labc The d-axis and q-axis currents i are obtained after coordinate transformation. Lq i Ld Then, the d-axis and q-axis currents i Lq i Ld The voltages obtained after virtual impedance Xv control are respectively related to the internal potentials E on the d and q axes. d E q Adding them together, we obtain the d-axis and q-axis reference voltages u. dref u qref The data is then fed into the voltage and current dual closed-loop control module 175, which in turn controls the data based on the d-axis and q-axis reference voltages u. dref u qref Grid connection point voltage u abc The output current i of the grid-side converter 140 Labc Output drive signals to control the grid-side converter 140.
[0053] The three-parameter collaborative adaptive adjustment module 172 includes a virtual inertia adaptive adjustment module 1721, a damping coefficient adaptive adjustment module 1722, and a virtual impedance adaptive adjustment module 1723. Figure 6 A schematic diagram of a virtual inertia adaptive adjustment module 1721 in a control system 170 according to an embodiment of this application is shown. Figure 6 As shown, the virtual inertia adaptive adjustment module 1721 is used to implement the control equation of the above formula (6). Figure 7 A schematic diagram of an adaptive damping coefficient adjustment module 1722 in a control system 170 according to an embodiment of this application is shown. Figure 7 As shown, the damping coefficient adaptive adjustment module 1722 is used to implement the control equation of the above formula (7). Figure 8 A schematic diagram of a virtual impedance adaptive adjustment module 1723 in a control system 170 according to an embodiment of this application is shown. Figure 8 As shown, the virtual impedance adaptive adjustment module 1723 is used to implement the control equation of the above formula (8). Figures 6 to 8 In this context, du / dt represents the differential operation module. This represents the absolute value operation module.
[0054] The virtual synchronous machine control method and flywheel energy storage system 100 of this application take into account the dynamic response of frequency and active power. When the system is disturbed, it can effectively reduce the rate of frequency change and frequency difference, and at the same time accelerate the response speed of active power.
[0055] The virtual synchronous machine control method and flywheel energy storage system of the energy storage system provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the virtual synchronous machine control method and flywheel energy storage system of the energy storage system of this application. The descriptions of the embodiments above are only for helping to understand the core ideas of this application and are not intended to limit this application. It should be noted that for those skilled in the art, several improvements and modifications can be made to this application without departing from the spirit and principles of this application, and these improvements and modifications should all fall within the protection scope of the appended claims.
Claims
1. A virtual synchronous machine control method for an energy storage system, characterized in that, include: Obtain the current angular frequency change rate and current angular frequency deviation of the virtual synchronizer; The virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation. The adjusted values of the virtual inertia, the damping coefficient, and the virtual impedance are input into the virtual synchronous machine control loop to control the grid-side converter of the energy storage system.
2. The virtual synchronous machine control method as described in claim 1, characterized in that, The values of virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: When the signs of the current angular frequency change rate and the current angular frequency deviation are the same, the virtual inertia and the damping coefficient are increased, and the virtual impedance is decreased. When the signs of the current angular frequency change rate and the current angular frequency deviation are opposite, the virtual inertia is reduced, the damping coefficient is increased, and the virtual impedance is reduced.
3. The virtual synchronous machine control method as described in claim 2, characterized in that, The values of virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: When the absolute value of the current angular frequency change rate is less than or equal to a predetermined first adjustment threshold, the value of the virtual inertia is kept unchanged from the initial value of the virtual inertia. When the absolute value of the current angular frequency change rate is greater than the first adjustment threshold, the magnitude of the product of the current angular frequency change rate and the current angular frequency deviation is further determined. When the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the product of the current angular frequency change rate and the current angular frequency deviation is greater than 0, the value of the virtual inertia is increased. When the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the product of the current angular frequency change rate and the current angular frequency deviation is less than or equal to 0, the value of the virtual inertia is reduced.
4. The virtual synchronous machine control method as described in claim 3, characterized in that, Increasing the value of the virtual inertia includes: The value of the virtual inertia is increased by a first predetermined value based on the initial value of the virtual inertia. The first predetermined value is equal to the product of a predetermined first virtual inertia adjustment coefficient and the absolute value of the current angular frequency change rate. Reducing the value of the virtual inertia includes: The value of the virtual inertia is reduced by a second predetermined value based on the initial value of the virtual inertia. The second predetermined value is equal to the product of a predetermined second virtual inertia adjustment coefficient and the absolute value of the current angular frequency change rate.
5. The virtual synchronous machine control method as described in claim 2, characterized in that, The values of virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: When the absolute value of the current angular frequency deviation is less than or equal to a predetermined second adjustment threshold, the value of the damping coefficient is kept constant at the initial value of the damping coefficient. When the absolute value of the current angular frequency deviation is greater than the second adjustment threshold, the value of the damping coefficient is increased.
6. The virtual synchronous machine control method as described in claim 5, characterized in that, Increasing the value of the damping coefficient includes: The value of the damping coefficient is increased by a third predetermined value based on the initial value of the damping coefficient. The third predetermined value is equal to the product of the predetermined damping coefficient adjustment coefficient and the absolute value of the current angular frequency deviation.
7. The virtual synchronous machine control method as described in claim 2, characterized in that, The values of virtual inertia, damping coefficient, and virtual impedance of the virtual synchronizer are adaptively adjusted based on the current angular frequency change rate and the current angular frequency deviation, including: When the absolute value of the current angular frequency change rate is less than or equal to a predetermined first adjustment threshold or the absolute value of the current angular frequency deviation is less than or equal to a predetermined second adjustment threshold, the value of the virtual impedance remains unchanged as the initial value of the virtual impedance. When the absolute value of the current angular frequency change rate is greater than the first adjustment threshold and the absolute value of the current angular frequency deviation is greater than the second adjustment threshold, the value of the virtual impedance is reduced.
8. The virtual synchronous machine control method as described in claim 7, characterized in that, Reducing the value of the virtual impedance includes: The value of the virtual impedance is reduced by a fourth predetermined value based on the initial value of the virtual impedance. The fourth predetermined value is equal to the product of a predetermined virtual impedance adjustment coefficient and the absolute value of the current angular frequency deviation.
9. The virtual synchronous machine control method as described in claim 1, characterized in that, Obtaining the current angular frequency change rate and current angular frequency deviation of the virtual synchronizer includes: Obtain the current mechanical power, current output power, and angular frequency deviation of the virtual synchronizer at the previous moment; The current rate of change of the angular frequency of the virtual synchronizer is obtained based on the current mechanical power, the current output power, and the angular frequency deviation at the previous moment, and based on the current value of the virtual inertia and the current value of the damping coefficient. The current angular frequency deviation of the virtual synchronizer is obtained based on the current angular frequency change rate of the virtual synchronizer.
10. A flywheel energy storage system, characterized in that, The system includes a flywheel rotor, a permanent magnet synchronous machine, a back-to-back converter, a DC bus capacitor, an LC filter, an AC power grid, and a control system. The back-to-back converter includes a machine-side converter and a grid-side converter. The DC bus capacitor is located between the machine-side converter and the grid-side converter. The flywheel rotor is used to store and release energy. The energy is transmitted to the AC power grid through the permanent magnet synchronous machine and the back-to-back converter and filtered by the LC filter. The control system uses the virtual synchronous machine control method of the energy storage system as described in any one of claims 1 to 9 to control the grid-side converter.