Virtual synchronous generator control method and system

Abstract

The application provides a virtual synchronous generator control method and system, and belongs to the technical field of virtual synchronous generator control. The value of the grid frequency observed by a low-bandwidth frequency-locked loop, a phase-locked loop or a high-bandwidth frequency-locked loop or phase-locked loop after low-pass filtering is used as a feedforward value of the frequency of the virtual synchronous generator. When the grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop is used as the feedforward value, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop and the zeros of the active-frequency transfer function of the virtual synchronous generator are cancelled. When the value of the grid frequency obtained by using the high-bandwidth frequency-locked loop or phase-locked loop and after low-pass filtering is used as the feedforward value, the poles of the low-pass filter transfer function and the zeros of the active-frequency transfer function of the virtual synchronous generator are cancelled. The application can eliminate the steady-state error of the active power regulation of the virtual synchronous generator, enhance the effect of suppressing the grid frequency change in the low-frequency band, and improve the effect of the virtual synchronous generator on the inertia support of the grid.

Description

Technical Field

[0001] This invention relates to the field of virtual synchronous generator control technology, and specifically to a virtual synchronous generator control method and system that can improve power and frequency response. Background Technology

[0002] With the high proportion of renewable energy connected to the grid, the inertia of the power system gradually decreases, weakening its ability to resist interference and maintain stable operation. The randomness and volatility of renewable energy cause fluctuations in grid frequency, further exacerbating this unfavorable situation and seriously threatening the safe and stable operation of the power system. Virtual synchronous generator technology in grid-connected converters increases system inertia by simulating the characteristics of a synchronous generator, thereby effectively improving the system's voltage and frequency support capabilities. A common method is to introduce virtual inertia and virtual damping feedback into the system to form a virtual synchronous generator inertia-damping integrated controller, simulating the inertia-damping characteristics of a synchronous generator. However, when the system reaches steady state, there is an error in active power. Existing research focuses on the influence of virtual inertia and virtual damping coefficients on the system for control optimization, but it does not eliminate the steady-state error of active power. For example, Chinese invention patent application CN118659472 A discloses a dynamic adaptive rate virtual synchronous generator control method and device, which can effectively reduce but not completely eliminate active power steady-state deviation. Summary of the Invention

[0003] The purpose of this invention is to provide a virtual synchronous generator control method and system that can improve power and frequency response, so as to solve at least one of the technical problems existing in the background art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a virtual synchronous generator control method, comprising:

[0006] The power grid frequency observed by low-bandwidth frequency-locked loops and phase-locked loops or the power grid frequency observed by high-bandwidth frequency-locked loops and phase-locked loops after low-pass filtering is used as the feedforward value of the virtual synchronous generator frequency.

[0007] Specifically, when using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator; when using a high-bandwidth frequency-locked loop or phase-locked loop to obtain the grid frequency and its low-pass filtered value as the feedforward, the poles of the low-pass filter transfer function cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator.

[0008] Furthermore, when using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, this includes: acquiring the grid-connected voltage U at the point of common coupling of the grid-connected converter. pcc Current I pcc Calculate the instantaneous active power P injected into the grid by the grid-connected converter. out The expected value of active power P ref With instantaneous active power value P out The difference is taken to obtain ΔP; ΔP is multiplied by the reciprocal of the rated angular frequency of the power grid to obtain the virtual mechanical torque T. m Virtual mechanical torque T m With virtual damping torque T D After the difference is calculated, it is controlled by a virtual inertia control loop. Multiplying them yields the deviation frequency Δω, where the virtual damping torque T D The deviation frequency Δω is controlled by a virtual damping control loop and D ω Multiplying them together, we get J ω For virtual rotational inertia, D ω The virtual damping coefficient is used; the grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop is used as the feedforward value ω of the grid-connected converter frequency. g * The equivalent closed-loop transfer function of a low-bandwidth frequency-locked loop or phase-locked loop is expressed as: Γ1 is the cutoff frequency of the low-bandwidth frequency-locked loop or phase-locked loop, and s is the Laplace operator; the feedforward value ω of the grid-connected converter frequency is... g * The frequency ω of the grid-connected converter is obtained by adding the deviation frequency Δω. v The frequency ω of the grid-connected converter v The phase angle θ of the grid-connected converter output voltage is obtained after integration; the setpoint value of the grid-connected converter output voltage amplitude E is generated by the reactive power controller, and the setpoint value of the grid-connected converter output voltage is obtained by integrating the amplitude value E and the phase angle θ; the drive signal of the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

[0009] Furthermore, the power grid frequency observation ω obtained from the low-bandwidth frequency-locked loop or phase-locked loop is... g * When used as a feedforward value for the virtual synchronous generator frequency, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator, including:

[0010] The power grid frequency observation ω obtained from a low-bandwidth frequency-locked loop or phase-locked loop g * When used as a feedforward value for the virtual synchronous generator frequency, the grid-connected converter outputs active power P. outWith active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0011]

[0012] Among them, J ω For virtual rotational inertia; D ω ω0 is the virtual damping coefficient; K is the rated voltage angular frequency; P The power amplification factor is 1. δ is the phase angle difference between the grid-connected converter output voltage and the grid voltage, E is the output voltage of the virtual synchronous generator, and U g X is the grid voltage, and X is the sum of the output impedance of the virtual synchronous generator and the impedance of the grid connection line.

[0013] Furthermore, based on the active power loop transfer function of the virtual synchronous generator, the bandwidth of the frequency-locked loop or phase-locked loop is adjusted to select... Make the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the virtual synchronous generator active power output P after cancellation. out With active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0014]

[0015] At this point, the active-frequency transfer function is: Its steady-state output value is zero under a step change in grid frequency, thereby eliminating the steady-state error of the active power regulation of the virtual synchronous generator.

[0016] Furthermore, when using the grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop, after low-pass filtering, as the feedforward value for the virtual synchronous generator frequency, this includes: acquiring the grid-connected voltage U at the point of common coupling of the grid-connected converter. pcc Current I pcc Calculate the instantaneous active power P injected into the grid by the grid-connected converter. out The expected value of active power P ref With the instantaneous value of active power P out The difference is taken to obtain ΔP; ΔP and Multiply to obtain virtual mechanical torque T m Where ω0 is the rated angular frequency of the power grid; virtual mechanical torque T m With virtual damping torque T D After the difference is calculated, it is controlled by a virtual inertia control loop. Multiplying them yields the deviation frequency Δω, where the virtual torque T D The deviation frequency Δω is controlled by a virtual damping control loop and D ω Multiplying them together, we get J ω For virtual rotational inertia, D ω This is the virtual damping coefficient; when the frequency-locked loop or phase-locked loop requires a higher bandwidth, the value ω is the grid frequency observed by the frequency-locked loop or phase-locked loop after passing through a low-pass filter. g * As the feedforward value of the grid-connected converter frequency, the equivalent closed-loop transfer function of the high-bandwidth frequency-locked loop or phase-locked loop can be expressed as: The transfer function of a low-pass filter can be expressed as: Γ2 is the cutoff frequency of the high-bandwidth frequency-locked loop or phase-locked loop, and ω1 is the cutoff frequency of the low-pass filter; the feedforward value ω of the grid-connected converter frequency is... g * The frequency ω of the grid-connected converter is obtained by adding the deviation frequency Δω. v The frequency ω of the grid-connected converter v The phase angle θ of the grid-connected converter output voltage is obtained after integration; the setpoint value of the grid-connected converter output voltage amplitude E is generated by the reactive power controller, and the setpoint value of the grid-connected converter output voltage is obtained by integrating the amplitude value E and the phase angle θ; the drive signal of the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

[0017] Furthermore, when the grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop is used as the feedforward value of the virtual synchronous generator frequency after being low-pass filtered, the bandwidth Γ2 of the frequency-locked loop or phase-locked loop is much higher than the bandwidth ω1 of the low-pass filter, making the poles of the low-pass filter the frequency feedforward transfer function of the grid-connected converter. It is the dominant pole, playing a leading role.

[0018] Furthermore, the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop is passed through a low-pass filter to obtain the value ω. g * As a feedforward value for the grid-connected converter frequency, when the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator, it includes:

[0019] The frequency of the power grid observed by a high-bandwidth frequency-locked loop or phase-locked loop is passed through a low-pass filter to obtain the value ω. g * When used as a feedforward value for the frequency of the grid-connected converter, the output active power P of the grid-connected converter is... out With active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0020]

[0021] Since the bandwidth of the frequency-locked loop or phase-locked loop is much higher than that of the low-pass filter at this time, i.e., Γ2 is much larger than ω1, the values ​​of the zero -(Γ2+ω1) and the pole -Γ2 approximately cancel each other out. Therefore:

[0022]

[0023] At this point, adjust the bandwidth of the low-pass filter and select... Make the transfer function of the low-pass filter that plays a dominant role The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the output active power P of the virtual synchronous generator after cancellation. out With active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0024]

[0025] At this point, the active-frequency transfer function of the virtual synchronous generator is: Its steady-state output value is zero under a step change in grid frequency, thereby eliminating the steady-state error of the active power regulation of the virtual synchronous generator.

[0026] In a second aspect, the present invention provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the virtual synchronous generator control method described in the first aspect, which can improve power and frequency response.

[0027] Thirdly, the present invention provides a computer device including a memory and a processor, the processor and the memory communicating with each other, the memory storing program instructions executable by the processor, and the processor calling the program instructions to execute the virtual synchronous generator control method as described in the first aspect, which can improve power and frequency response.

[0028] Fourthly, the present invention provides an electronic device comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the virtual synchronous generator control method as described in the first aspect, which can improve power and frequency response.

[0029] The beneficial effects of this invention are: it can eliminate the steady-state error of the active power regulation of the virtual synchronous generator; the numerator of the active power-frequency transfer function of the virtual synchronous generator has a differential term; and the output active power can also dampen the change of grid frequency, thereby improving the effect of the virtual synchronous generator on grid inertia support.

[0030] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0031] 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.

[0032] Figure 1 This is a control structure block diagram of the virtual synchronous generator control method that can improve power and frequency response according to an embodiment of the present invention.

[0033] Figure 2 This is a control block diagram of the virtual synchronous generator control method that can improve power and frequency response according to Embodiment 1 of the present invention.

[0034] Figure 3 This is a control block diagram of the virtual synchronous generator control method that can improve power and frequency response according to Embodiment 2 of the present invention. Detailed Implementation

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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. 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.

[0040] 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. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0041] 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.

[0042] Example 1

[0043] In this embodiment 1, a virtual synchronous generator control system is first provided, including a controller configured to: use the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency; wherein, when using the grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop as the feedforward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop are canceled out with the zeros of the active-frequency transfer function of the virtual synchronous generator.

[0044] A common method is to introduce virtual inertia and virtual damping feedback into the system to construct a virtual synchronous generator's inertia-damping integrated controller, simulating the inertia-damping characteristics of a synchronous generator. The output power P of the virtual synchronous generator... out It can be represented as:

[0045]

[0046] Among them, J ω For virtual rotational inertia; D ω ω is the virtual damping coefficient; ω0 is the rated voltage angular frequency; ω g P is the angular frequency of the grid voltage.ref Active power reference command; K P The power amplification factor is 1. δ is the phase angle difference between the grid-connected converter output voltage and the grid voltage, E is the grid-connected converter output voltage, and U... g Let X be the grid voltage, and X be the sum of the output impedance of the grid-connected converter and the grid connection impedance. The steady-state output active power can be expressed as:

[0047]

[0048] It can be seen that the steady-state output active power consists of two parts: one is the active power reference command P. ref Secondly, the power deviation D caused by the change in angular frequency. ω ω0(ω0-ω g It is evident that there is an error in the active power when the system reaches steady state.

[0049] Combination Figure 1 , Figure 2 As shown, to address the aforementioned issues, this embodiment utilizes the system described above to implement a virtual synchronous generator control method that improves power and frequency response. The grid frequency observed by the low-bandwidth frequency-locked loop (LLL) or phase-locked loop (PLL) is used as the feedforward value for the virtual synchronous generator frequency. When using the grid frequency observed by the low-bandwidth LLL or PLL as the feedforward, the poles of the equivalent closed-loop transfer function of the LLL or PLL are canceled out with the zeros of the active-frequency transfer function of the virtual synchronous generator.

[0050] The specific steps are as follows:

[0051] 1) By collecting the grid-connected voltage U at the common connection point of the grid-connected converter pcc Current I pcc Calculate the instantaneous active power P injected into the grid by the grid-connected converter. out ;

[0052] 2) The expected value of active power P ref With the instantaneous value of active power P out By taking the difference, we obtain ΔP;

[0053] 3) ΔP and Multiply to obtain virtual mechanical torque T m Where ω0 is the rated angular frequency of the power grid;

[0054] 4) Virtual mechanical torque T m With virtual damping torque T D After the difference is calculated, it is controlled by a virtual inertia control loop. Multiplying them yields the deviation frequency Δω, where the virtual damping torque T D The deviation frequency Δω is controlled by a virtual damping control loop and Dω Multiplying them together, we get J ω For virtual rotational inertia, D ω This is the virtual damping coefficient;

[0055] 5) The grid frequency ω observed by the low-bandwidth frequency-locked loop or phase-locked loop g * As the feedforward value of the grid-connected converter frequency, the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop can be expressed as: Γ1 is the cutoff frequency of a low-bandwidth frequency-locked loop or phase-locked loop;

[0056] 6) Feedforward value ω of the grid-connected converter frequency g * The frequency ω of the grid-connected converter is obtained by adding the deviation frequency Δω obtained in step 4). v ;

[0057] 7) The frequency ω of the grid-connected converter v The phase angle θ of the grid-connected converter output voltage is obtained through integration.

[0058] 8) The given value of the output voltage amplitude E of the grid-connected converter is generated by the reactive power controller. The given value of the output voltage of the grid-connected converter is obtained by integrating the amplitude E of the output voltage of the grid-connected converter and the phase angle θ.

[0059] 9) The drive signal for the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

[0060] Figure 2 The control block diagram shown represents the observed value ω of the grid frequency obtained from a low-bandwidth frequency-locked loop or phase-locked loop. g * As the feedforward value of the virtual synchronous generator frequency, according to Figure 2 The output active power P of the grid-connected converter can be obtained. out With active power given value P ref and grid voltage angular frequency ω g The transfer function can be expressed as:

[0061]

[0062] Among them, J ω For virtual rotational inertia; D ω ω0 is the virtual damping coefficient; ω0 is the rated voltage angular frequency. E represents the output voltage of the virtual synchronous generator, U g X is the grid voltage, and X is the sum of the output impedance of the virtual synchronous generator and the impedance of the grid connection line.

[0063] At this point, adjust the bandwidth of the frequency-locked loop or phase-locked loop, and take... Make the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop. The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the output active power P of the virtual synchronous generator after cancellation. out With active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0064]

[0065] At this point, the active-frequency transfer function of the virtual synchronous generator is: Its steady-state output is zero under a step change in grid frequency, thus eliminating the steady-state error of the virtual synchronous generator's active power regulation. Furthermore, because the numerator of this transfer function has a differential term, the output active power can also dampen changes in grid frequency, thereby improving the virtual synchronous generator's support for grid inertia.

[0066] Example 2

[0067] Combination Figure 1 , Figure 3 As shown in Example 2, a virtual synchronous generator control method that improves power and frequency response uses the grid frequency observed by a high-bandwidth frequency-locked loop (LLL) or phase-locked loop (PLL) after low-pass filtering as the feedforward value for the virtual synchronous generator frequency. When using a high-bandwidth LLL or PLL to obtain the grid frequency and then using its low-pass filtered value as feedforward, the poles of the low-pass filter cancel out the zeros of the virtual synchronous generator's active-frequency transfer function. The specific steps are as follows:

[0068] 1) By collecting the grid-connected voltage U at the common connection point of the grid-connected converter pcc Current I pcc Calculate the instantaneous active power P injected into the grid by the grid-connected converter. out ;

[0069] 2) The expected value of active power P ref With the instantaneous value of active power P out By taking the difference, we obtain ΔP;

[0070] 3) ΔP and Multiply to obtain virtual mechanical torque T m Where ω0 is the rated angular frequency of the power grid;

[0071] 4) Virtual mechanical torque T m With virtual damping torque T D After the difference is calculated, it is controlled by a virtual inertia control loop. Multiplying them yields the deviation frequency Δω, where the virtual damping torque T DThe deviation frequency Δω is controlled by a virtual damping control loop and D ω Multiplying them together, we get J ω For virtual rotational inertia, D ω This is the virtual damping coefficient;

[0072] 5) When a frequency-locked loop or phase-locked loop requires a high bandwidth, the value ω of the grid frequency observed by the frequency-locked loop or phase-locked loop is passed through a low-pass filter. g * As the feedforward value of the grid-connected converter frequency, the equivalent closed-loop transfer function of the high-bandwidth frequency-locked loop or phase-locked loop can be expressed as: The transfer function of a low-pass filter can be expressed as: Γ2 is the cutoff frequency of the high-bandwidth frequency-locked loop (LLL) or phase-locked loop (PLL), and ω1 is the cutoff frequency of the low-pass filter. In this case, the bandwidth Γ2 of the LLL or PLL is much higher than the bandwidth ω1 of the low-pass filter, making the poles of the low-pass filter the frequency feedforward transfer function of the grid-connected converter. The dominant pole plays a leading role;

[0073] 6) The feedforward value ω of the grid-connected converter frequency g * The frequency ω of the grid-connected converter is obtained by adding the deviation frequency Δω obtained in step 4). v ;

[0074] 7) The frequency ω of the grid-connected converter v The phase angle θ of the grid-connected converter output voltage is obtained through integration.

[0075] 8) The given value of the output voltage amplitude E of the grid-connected converter is generated by the reactive power controller. The given value of the output voltage of the grid-connected converter is obtained by integrating the amplitude E of the output voltage of the grid-connected converter and the phase angle θ.

[0076] 9) The drive signal for the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

[0077] Figure 3 The control block diagram shown represents the value ω of the grid frequency observed using a high-bandwidth frequency-locked loop or phase-locked loop after passing through a low-pass filter. g * As the feedforward value of the grid-connected converter frequency, according to Figure 3 The output active power P of the grid-connected converter can be obtained. out With active power given value P ref and grid voltage angular frequency ω g The transfer function can be expressed as:

[0078]

[0079] Since the bandwidth of the frequency-locked loop or phase-locked loop is much higher than that of the low-pass filter at this point, i.e., Γ2 is much larger than ω1, the values ​​of the zero -(Γ2+ω1) and the pole -Γ2 are basically the same, approximately canceling each other out. This can be expressed as:

[0080]

[0081] At this point, adjust the bandwidth of the low-pass filter and select... Make the transfer function of the low-pass filter that plays a dominant role The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the output active power P of the virtual synchronous generator after cancellation. out With active power given value P ref and grid voltage angular frequency ω g The transfer function is:

[0082]

[0083] At this point, the active-frequency transfer function of the virtual synchronous generator is: Its steady-state output is zero under a step change in grid frequency, thus eliminating the steady-state error of the virtual synchronous generator's active power regulation. Furthermore, because the numerator of this transfer function has a differential term, the output active power can also dampen changes in grid frequency, thereby improving the virtual synchronous generator's support for grid inertia.

[0084] Example 3

[0085] This embodiment 3 provides a non-transitory computer-readable storage medium for storing computer instructions. When executed by a processor, the computer instructions implement the virtual synchronous generator control method described above, which improves power and frequency response. The method includes:

[0086] The grid frequency observed by low-bandwidth frequency-locked loops (LLLs) or phase-locked loops (PLLs), or the grid frequency observed by high-bandwidth LLLs, after low-pass filtering, is used as the feedforward value for the virtual synchronous generator (SSR) frequency. When using the grid frequency observed by a low-bandwidth LLL or PLL as the feedforward, the poles of the equivalent closed-loop transfer function of the LLL or PLL cancel out the zeros of the active-frequency transfer function of the SSR. When using a high-bandwidth LLL or PLL to obtain the grid frequency and then using its low-pass filtered value as the feedforward, the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the SSR.

[0087] Example 4

[0088] This embodiment 4 provides a computer device, including a memory and a processor, wherein the processor and the memory communicate with each other, and the memory stores program instructions that can be executed by the processor. The processor calls the program instructions to execute the virtual synchronous generator control method described above, which can improve power and frequency response. The method includes:

[0089] The grid frequency observed by low-bandwidth frequency-locked loops (LLLs) or phase-locked loops (PLLs), or the grid frequency observed by high-bandwidth LLLs, after low-pass filtering, is used as the feedforward value for the virtual synchronous generator (SSR) frequency. When using the grid frequency observed by a low-bandwidth LLL or PLL as the feedforward, the poles of the equivalent closed-loop transfer function of the LLL or PLL cancel out the zeros of the active-frequency transfer function of the SSR. When using a high-bandwidth LLL or PLL to obtain the grid frequency and then using its low-pass filtered value as the feedforward, the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the SSR.

[0090] Example 5

[0091] This embodiment 5 provides an electronic device, including: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the virtual synchronous generator control method described above, which can improve power and frequency response. The method includes:

[0092] The grid frequency observed by low-bandwidth frequency-locked loops (LLLs) or phase-locked loops (PLLs), or the grid frequency observed by high-bandwidth LLLs, after low-pass filtering, is used as the feedforward value for the virtual synchronous generator (SSR) frequency. When using the grid frequency observed by a low-bandwidth LLL or PLL as the feedforward, the poles of the equivalent closed-loop transfer function of the LLL or PLL cancel out the zeros of the active-frequency transfer function of the SSR. When using a high-bandwidth LLL or PLL to obtain the grid frequency and then using its low-pass filtered value as the feedforward, the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the SSR.

[0093] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0095] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0097] 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, characterized in that, include: The power grid frequency observed by low-bandwidth frequency-locked loops and phase-locked loops or the power grid frequency observed by high-bandwidth frequency-locked loops and phase-locked loops after low-pass filtering is used as the feedforward value of the virtual synchronous generator frequency. Specifically, when using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator; when using a high-bandwidth frequency-locked loop or phase-locked loop to obtain the grid frequency and its low-pass filtered value as the feedforward, the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator.

2. The virtual synchronous generator control method according to claim 1, characterized in that, When using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value for the virtual synchronous generator frequency, this includes: acquiring the grid-connected voltage at the point of common coupling of the grid-connected converter. Current Calculate the instantaneous active power injected into the grid by the grid-connected converter. ; the expected value of active power With instantaneous active power value Get by doing bad things , The virtual mechanical torque is obtained by multiplying it by the reciprocal of the rated angular frequency of the power grid. Virtual mechanical torque With virtual damping torque After the difference is calculated, it is controlled by a virtual inertia control loop. Multiply to obtain the deviation frequency The virtual damping torque From the deviation frequency Through virtual damping control and Multiplying them together, we get For virtual rotational inertia, This is the virtual damping coefficient; it represents the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop. As the feedforward value for the grid-connected converter frequency, the equivalent closed-loop transfer function of the low-bandwidth frequency-locked loop or phase-locked loop is expressed as follows: , The cutoff frequency of the low-bandwidth frequency-locked loop or phase-locked loop is given by s, where s is the Laplace operator; the feedforward value of the grid-connected converter frequency is given by s. With deviation frequency The frequency of the grid-connected converter is obtained by adding them together. ; the frequency of the grid-connected converter The phase angle of the grid-connected converter output voltage is obtained after integration. ; Output voltage amplitude of grid-connected converter The setpoint is generated by the reactive power controller, integrating the amplitude of the grid-connected converter output voltage. and phase angle The given value of the output voltage of the grid-connected converter is obtained; the drive signal of the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

3. The virtual synchronous generator control method according to claim 2, characterized in that, The power grid frequency observations obtained from low-bandwidth frequency-locked loops or phase-locked loops When used as a feedforward value for the virtual synchronous generator frequency, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator, including: The power grid frequency observations obtained from low-bandwidth frequency-locked loops or phase-locked loops When used as a feedforward value for the virtual synchronous generator frequency, the grid-connected converter outputs active power. With active power setpoint and grid voltage angular frequency The transfer function is: ； in, This is a virtual moment of inertia; This is the virtual damping coefficient; The angular frequency of the rated voltage; The power amplification factor is 1. , The phase angle difference between the output voltage of the grid-connected converter and the grid voltage. This is the output voltage of the virtual synchronous generator. This is the grid voltage. It is the sum of the output impedance of the virtual synchronous generator and the impedance of the grid connection line.

4. The virtual synchronous generator control method according to claim 3, characterized in that, Based on the active power loop transfer function of the virtual synchronous generator, adjust the bandwidth of the frequency-locked loop or phase-locked loop, and select... Make the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop. The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the canceled virtual synchronous generator active power output. With active power setpoint and grid voltage angular frequency The transfer function is: ； At this point, the active-frequency transfer function is: Its steady-state output value is zero under a step change in grid frequency, thereby eliminating the steady-state error of the active power regulation of the virtual synchronous generator.

5. The virtual synchronous generator control method according to claim 1, characterized in that, When using the grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop, after low-pass filtering, as the feedforward value for the virtual synchronous generator frequency, this includes: acquiring the grid-connected voltage at the point of common coupling of the grid-connected converter. Current Calculate the instantaneous active power injected into the grid by the grid-connected converter. ; the expected value of active power With active power instantaneous value Doing bad things, getting... ; and Multiply to obtain virtual mechanical torque ,in Rated angular frequency of the power grid; virtual mechanical torque With virtual damping torque After the difference is calculated, it is controlled by a virtual inertia control loop. Multiply to obtain the deviation frequency The virtual torque From the deviation frequency Through virtual damping control and Multiplying them together, we get For virtual rotational inertia, This is the virtual damping coefficient; when a frequency-locked loop or phase-locked loop requires higher bandwidth, the value of the grid frequency observed by the frequency-locked loop or phase-locked loop after passing through a low-pass filter is used. As the feedforward value of the grid-connected converter frequency, the equivalent closed-loop transfer function of the high-bandwidth frequency-locked loop or phase-locked loop can be expressed as: The transfer function of a low-pass filter can be expressed as: , This is the cutoff frequency of a high-bandwidth frequency-locked loop or phase-locked loop. The low-pass filter cutoff frequency; the feedforward value of the grid-connected converter frequency. With deviation frequency The frequency of the grid-connected converter is obtained by adding them together. ; the frequency of the grid-connected converter The phase angle of the grid-connected converter output voltage is obtained after integration. ; Output voltage amplitude of grid-connected converter The setpoint is generated by the reactive power controller, integrating the amplitude of the grid-connected converter output voltage. and phase angle The given value of the output voltage of the grid-connected converter is obtained; the drive signal of the grid-connected converter is obtained through the voltage closed-loop controller and the pulse width modulator.

6. The virtual synchronous generator control method according to claim 5, characterized in that, When the grid frequency observed by a high-bandwidth frequency-locked loop (LLL) or phase-locked loop (PLL) is low-pass filtered and used as the feedforward value for the virtual synchronous generator frequency, the bandwidth of the LLL or PLL... Much higher than the bandwidth of a low-pass filter This makes the poles of the low-pass filter equal to the frequency feedforward transfer function of the grid-connected converter. It is the dominant pole, playing a leading role.

7. The virtual synchronous generator control method according to claim 5, characterized in that, The value obtained by passing the power grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop through a low-pass filter. As a feedforward value for the grid-connected converter frequency, when the poles of the low-pass filter cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator, it includes: The frequency of the power grid observed by a high-bandwidth frequency-locked loop or phase-locked loop is passed through a low-pass filter. When used as a feedforward value for the frequency of the grid-connected converter, the output active power of the grid-connected converter is... With active power setpoint and grid voltage angular frequency The transfer function is: ； Since the bandwidth of the frequency-locked loop or phase-locked loop is much higher than the bandwidth of the low-pass filter at this time, that is... Much larger Therefore, zero point With the extreme point The values ​​of are approximately canceled out, then: ； At this point, adjust the bandwidth of the low-pass filter and select... This makes the transfer function of the low-pass filter, which plays a dominant role, more important. The poles can be correlated with the active-frequency transfer function of the virtual synchronous generator. Zero-point cancellation yields the output active power of the virtual synchronous generator after cancellation. With active power setpoint and grid voltage angular frequency The transfer function is: ； At this point, the active-frequency transfer function of the virtual synchronous generator is: Its steady-state output value is zero under a step change in grid frequency, thereby eliminating the steady-state error of the active power regulation of the virtual synchronous generator.

8. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the virtual synchronous generator control method as described in any one of claims 1-6.

9. A computer device, characterized in that, The system includes a memory and a processor, which communicate with each other. The memory stores program instructions that can be executed by the processor, and the processor invokes the program instructions to execute the virtual synchronous generator control method as described in any one of claims 1-6.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions that implement the virtual synchronous generator control method as described in any one of claims 1-6.

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