Virtual synchronous generator power and frequency decoupling control method
By introducing differential feedforward control and proportional feedforward control into the virtual synchronous generator, active power tracking and frequency support control are decoupled, thereby improving the power tracking response speed and frequency support capability of the virtual synchronous generator and realizing dual-function grid support.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING JIAOTONG UNIV
- Filing Date
- 2023-01-18
- Publication Date
- 2026-06-09
Smart Images
Figure CN116094044B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of converter control technology, specifically to a virtual synchronous generator control method based on active power tracking and frequency support control decoupling. Background Technology
[0002] New energy power generation is characterized by intermittency, randomness, and uncertainty. Large-scale grid connection of new energy sources poses a severe challenge to the stable operation of the power grid. In order to enable converters to provide inertia support and frequency regulation services for the power grid, various converter control methods have emerged. Among them, virtual synchronous generator control technology can provide inertia support and primary frequency regulation services for the power grid, and therefore has received widespread attention in the industry.
[0003] Existing traditional virtual synchronous generator control schemes suffer from the following problems: the poles of active power point tracking (APS) and frequency support control (FSC) coincide, and the two are coupled through these poles. When increasing the poles of APS to improve power response speed, the power output capability of FSC is attenuated. This traditional virtual synchronous generator scheme struggles to simultaneously improve both the speed of APS and the power output capability of FSC. Summary of the Invention
[0004] The purpose of this invention is to provide a virtual synchronous generator control method based on active power tracking and frequency support control decoupling, so as to solve at least one of the technical problems existing in the background art.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] This invention provides a virtual synchronous generator control method based on the decoupling of active power tracking and frequency support control, comprising: adding differential feedforward control to the transfer function of the active power tracking control of the virtual synchronous generator, reducing the active power tracking control to a first-order system, enabling the active power tracking control to respond to power commands quickly and without overshoot, and coupling the active power tracking control and frequency support control through poles.
[0007] Preferably, proportional control, derivative control, and high-pass filtering are introduced into the transfer function of the frequency support control of the virtual synchronous generator to eliminate steady-state errors caused by damping, improve the zero-pole degrees of freedom of the frequency support control, eliminate the coupling of the active power tracking control, and improve the power output capability of the frequency support control.
[0008] Preferably, by incorporating differential feedforward control into the transfer function of the virtual synchronous generator active power tracking control, the transfer function becomes:
[0009]
[0010] Where J is the inertia coefficient of the virtual synchronous generator, and D p K is the droop coefficient. D Where ω0 is the damping coefficient, K is the rated angular frequency, and K is the proportionality coefficient from power angle to power. d These are the coefficients of the differential controller.
[0011] Preferably, the poles are P1 and P2, and the zero is Z. 1， Then there is
[0012]
[0013] Using the pole-zero cancellation method, let the zero Z1 equal P1, then the transfer function becomes:
[0014]
[0015] At this point, the active power tracking control is reduced to a first-order system, and the active power tracking control and frequency support control are coupled through pole P2.
[0016] Preferably, by introducing proportional control, derivative control, and high-pass filtering into the transfer function of the frequency support control of the virtual synchronous generator, the transfer function becomes:
[0017]
[0018] Preferably, when s = 0, it is determined by G. ω-p From the expression, we can know K D This causes a steady-state error in the system, let K g equal to -K D If the steady-state error caused by damping can be eliminated, then:
[0019]
[0020] Let the zeros of the numerator be Z1 and Z2, and the poles of the denominator be P1, P2, and P3, where P3 equals 1 / D. Then:
[0021]
[0022] Let Z3 = P1, the frequency support control transfer function is:
[0023]
[0024] Depend on achievable
[0025]
[0026] Among them, Z2 and P3 can be accessed through K. rT and D are freely adjustable, allowing the differential element determined by Z2 and P3 to encompass the range of grid frequency variations. When the grid frequency changes, frequency support control provides inertial power support to the grid. Since the response speed of active power tracking control is much faster than that of frequency support control, and P2 determines the response speed of active power tracking control while P3 and Z2 determine the inertia of frequency support control, P2 is much larger than P3, thus achieving decoupling between active power tracking control and frequency support control.
[0027] The beneficial effects of this invention are as follows: Active power tracking control is reduced from a second-order system to a first-order system through differential feedforward control; proportional feedforward control is introduced into the forward channel of frequency support control to eliminate steady-state errors caused by damping; using a high-pass filter and a differential controller, on the one hand, slow-response poles are eliminated through zero-pole cancellation, keeping the frequency support control a second-order system; on the other hand, the adjustable degrees of freedom of the zeros and poles of the frequency support control are increased, thereby enhancing the inertial power output capability of the frequency support control.
[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description
[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1 This is a block diagram of active power tracking control according to an embodiment of the present invention.
[0031] Figure 2 This is a block diagram of frequency support control according to an embodiment of the present invention.
[0032] Figure 3 This is a block diagram of a traditional virtual synchronous generator control system in the existing technology. Detailed Implementation
[0033] 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 denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0034] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0035] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.
[0036] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.
[0037] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.
[0038] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.
[0039] In the description of this specification, the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this technology and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this technology.
[0040] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of these terms in this art according to the specific circumstances.
[0041] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments, and the specific embodiments do not constitute a limitation on the embodiments of the present invention.
[0042] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.
[0043] Example
[0044] This embodiment provides a virtual synchronous generator control strategy based on the decoupling of active power tracking control and frequency support control. The active power tracking control is downgraded from a second-order system to a first-order system through differential feedforward control. Proportional feedforward control is introduced into the forward channel of the frequency support control to eliminate steady-state errors caused by damping. A high-pass filter and a differential controller are used to eliminate slow-response poles through zero-pole cancellation, keeping the frequency support control a second-order system. Furthermore, the adjustable degrees of freedom of the zeros and poles of the frequency support control are increased, thereby enhancing the inertial power output capability of the frequency support control.
[0045] Specifically, the generator solution described in this embodiment is as follows:
[0046] 1. Power Tracking Control (PTC) Order Reduction
[0047] Traditional virtual synchronous generators, such as Figure 3 As shown, the grid-connected output power is:
[0048]
[0049] The active power tracking control transfer function is:
[0050]
[0051] To achieve fast, overshoot-free command power tracking, this embodiment employs the following method: Figure 1 The differential feedforward control shown below transforms the transfer function into:
[0052]
[0053] In the formula, K d Let P1 and P2 be the coefficients of the differential controller. Let the poles be P1 and P2, and the zero be Z1. Then we have...
[0054] Using the pole-zero cancellation method, let the zero Z1 equal P1, then the transfer function becomes:
[0055]
[0056] At this point, active power tracking control can respond to power commands quickly and without overshoot.
[0057] 2. Decoupling of active power tracking control and frequency support control
[0058] The traditional frequency support control transfer function is:
[0059]
[0060] like Figure 2 As shown, by introducing a proportional controller, a derivative controller, and a high-pass filter, the transfer function becomes:
[0061]
[0062] When s = 0, by G ω-p From the expression, we can know K D This causes a steady-state error in the system, let K g equal to -K D If the steady-state error caused by damping can be eliminated, then:
[0063]
[0064] Let the zeros of the numerator be Z1 and Z2, and the poles of the denominator be P1, P2, and P3, where P3 equals 1 / D.
[0065]
[0066] Let Z3 = P1, the frequency support control transfer function is:
[0067]
[0068] Depend on achievable
[0069]
[0070] From the expressions for Z2 and P3, it can be seen that Z2 and P3 can be obtained through K. r T and D are freely adjustable, allowing the differential element determined by Z2 and P3 to encompass the range of grid frequency variations. When the grid frequency changes, frequency support control can provide rapid inertial power support to the grid.
[0071] This embodiment decouples the power point tracking (PPT) control and frequency support control of the virtual synchronous generator. The improved response speed of PPT control no longer affects the power output of frequency support control. PPT control, with its fast response speed, can provide auxiliary frequency regulation services to the power grid. Frequency support control provides rapid inertia support to the power grid. A single virtual synchronous generator achieves dual functions, realizing the goal of "one machine, two uses."
[0072] In summary, the virtual synchronous generator control strategy based on the decoupling of active power point tracking (APS) and frequency support control described in this embodiment of the invention decouples APS and frequency support control. APS has a fast response speed, providing rapid auxiliary frequency regulation services to the power grid; frequency support control provides rapid inertial power support to the power grid. The introduction of proportional feedforward in APS reduces the active power point tracking control from a second-order system to a first-order system, while the introduction of proportional feedforward eliminates steady-state errors caused by damping. The introduction of a differential controller and a high-pass filter in frequency support control increases the zero-pole degrees of freedom, eliminating the coupling of APS. Furthermore, the introduction of a differential controller and a high-pass filter enhances the power output capability of frequency support control.
[0073] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.
Claims
1. A virtual synchronous generator control method based on active power tracking and frequency support control decoupling, characterized in that, include: By adding differential feedforward control to the transfer function of the active power tracking control of the virtual synchronous generator and then canceling the zeros and poles, the active power tracking control is reduced to a first-order system, and the active power tracking control can respond to the power command quickly without overshoot. Introducing proportional control, derivative control, and high-pass filtering into the transfer function of the frequency support control of the virtual synchronous generator eliminates steady-state errors caused by damping. Then, the zero-pole cancellation is performed to increase the zero-pole degrees of freedom of the frequency support control, eliminate the coupling of active power tracking control, and improve the power output capability of the frequency support control. The active power tracking control and the frequency support control are coupled through a single pole.
2. The virtual synchronous generator control method based on active power tracking and frequency support control decoupling as described in claim 1, characterized in that, By adding differential feedforward control to the transfer function of the active power tracking control of the virtual synchronous generator, the transfer function becomes: ； Where J is the inertia coefficient of the virtual synchronous generator, and D p K is the droop coefficient. D Where ω0 is the damping coefficient, K is the rated angular frequency, and K is the proportionality coefficient from power angle to power. d These are the coefficients of the differential controller.
3. The virtual synchronous generator control method based on active power tracking and frequency support control decoupling as described in claim 2, characterized in that, Let the poles be P1 and P2, and the zero be Z1, then we have , , ； Using the pole-zero cancellation method, let the zero Z1 equal P1, then the transfer function becomes: ； At this point, the active power tracking control is reduced to a first-order system, and the active power tracking control and frequency support control are coupled through pole P2.
4. The virtual synchronous generator control method based on active power tracking and frequency support control decoupling as described in claim 3, characterized in that, By introducing proportional control, derivative control, and high-pass filtering into the transfer function of the frequency support control of the virtual synchronous generator, the transfer function becomes: ； Where Kg is the proportional controller coefficient, Kr is the differential controller coefficient, and T and D are the numerator and denominator time constants of the high-pass filter, respectively.
5. The virtual synchronous generator control method based on active power tracking and frequency support control decoupling as described in claim 4, characterized in that, When s=0, by From the expression, we can know K D This causes a steady-state error in the system, let K g equal to -K D If the steady-state error caused by damping can be eliminated, then: ； Let the zeros of the numerator be Z2 and Z3, and the poles of the denominator be P1, P2, and P3, where P3 equals 1 / D. Then: ； Let Z3 = P1, the frequency support control transfer function is: ； Depend on , have to ； Among them, Z2 and P3 are connected through K. r T and D are freely adjustable, so that the differential element determined by Z2 and P3 covers the range of grid frequency changes. When the grid frequency changes, frequency support control provides inertial power support for the grid. Since the response speed of active power tracking control is much higher than that of frequency support control, and P2 determines the response speed of active power tracking control, while P3 and Z2 determine the inertia of frequency support control, P2 is much larger than P3, thus achieving decoupling between active power tracking control and frequency support control.