Virtual synchronous generator control method and system

Abstract

The invention provides a virtual synchronous generator control method and system, belongs to the technical field of virtual synchronous generator control, and takes a value of a power grid frequency observed by a low-bandwidth frequency-locked loop and a phase-locked loop or a high-bandwidth frequency-locked loop and a phase-locked loop after low-pass filtering as a feedforward value of the frequency of a virtual synchronous generator. When the power grid frequency observed by using a low-bandwidth frequency-locked loop or phase-locked loop is used as feedforward, the pole of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop is offset with the zero point of the active-frequency transfer function of the virtual synchronous generator; and when a high-bandwidth frequency-locked loop or phase-locked loop is used for obtaining a power grid frequency and a value obtained after low-pass filtering is used as a feedforward, a pole of a transfer function of a low-pass filter and a zero point of an active-frequency transfer function of the virtual synchronous generator are offset. According to the method, the steady-state error of active power adjustment of the virtual synchronous generator can be eliminated, the effect of suppressing the frequency change of the power grid at a low-frequency band is enhanced, and the effect of supporting the inertia of the power grid by the virtual synchronous generator is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of virtual synchronous generator control, and particularly relates to a virtual synchronous generator control method and system capable of improving power and frequency response. Background Art

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

[0003] The purpose of the present invention is to provide a virtual synchronous generator control method and system capable of improving power and frequency response to solve at least one of the technical problems existing in the above background art.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

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

[0006] Taking the value obtained by low-pass filtering the grid frequency observed by a low-bandwidth frequency-locked loop and phase-locked loop or the grid frequency observed by a high-bandwidth frequency-locked loop and phase-locked loop as the feed-forward value of the virtual synchronous generator frequency;

[0007] Wherein, when using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feed-forward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop are cancelled with the zeros of the active-power frequency transfer function of the virtual synchronous generator; when using the value obtained by low-pass filtering the grid frequency obtained by a high-bandwidth frequency-locked loop or phase-locked loop as the feed-forward, the poles of the low-pass filter transfer function are cancelled with the zeros of the active-power frequency transfer function of the virtual synchronous generator.

[0008] Further, 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, it includes: by collecting the grid-connected voltage U at the point of common coupling of the grid-connected converter pcc , current I pcc , calculating the instantaneous active power P injected by the grid-connected converter into the grid out ; subtracting the instantaneous active power value P from the expected value P of the active power to obtain ΔP; multiplying ΔP by the reciprocal of the rated angular frequency of the grid to obtain the virtual mechanical torque T ref ; subtracting the virtual mechanical torque T from the virtual damping torque T out and multiplying the result by through the virtual inertia control link to obtain the deviation frequency Δω, where the virtual damping torque T m is obtained by multiplying the deviation frequency Δω by D through the virtual damping control link m , J D is the virtual moment of inertia, and D is the virtual damping coefficient; using the grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value ω of the grid-connected converter frequency D , where the equivalent closed-loop transfer function of the low-bandwidth frequency-locked loop or phase-locked loop is expressed as ω Γ ω is the cut-off frequency of the low-bandwidth frequency-locked loop or phase-locked loop, and s is the Laplace operator; adding the feedforward value ω of the grid-connected converter frequency ω to the deviation frequency Δω to obtain the frequency ω of the grid-connected converter g * ; obtaining the phase angle θ of the output voltage of the grid-connected converter after passing the frequency ω of the grid-connected converter through an integration link; the given value of the amplitude E of the output voltage of the grid-connected converter is generated by a reactive power controller, and integrating the amplitude E and phase angle θ of the output voltage of the grid-connected converter to obtain the given value of the output voltage of the grid-connected converter; obtaining the drive signal of the grid-connected converter through a voltage closed-loop controller and a pulse width modulator. Γ 1 is the cut-off frequency of the low-bandwidth frequency-locked loop or phase-locked loop, and s is the Laplace operator; adding the feedforward value ω of the grid-connected converter frequency g * to the deviation frequency Δω to obtain the frequency ω of the grid-connected converter v ; obtaining the phase angle θ of the output voltage of the grid-connected converter after passing the frequency ω of the grid-connected converter through an integration link; the given value of the amplitude E of the output voltage of the grid-connected converter is generated by a reactive power controller, and integrating the amplitude E and phase angle θ of the output voltage of the grid-connected converter to obtain the given value of the output voltage of the grid-connected converter; obtaining the drive signal of the grid-connected converter through a voltage closed-loop controller and a pulse width modulator. v ; obtaining the phase angle θ of the output voltage of the grid-connected converter after passing the frequency ω of the grid-connected converter through an integration link; the given value of the amplitude E of the output voltage of the grid-connected converter is generated by a reactive power controller, and integrating the amplitude E and phase angle θ of the output voltage of the grid-connected converter to obtain the given value of the output voltage of the grid-connected converter; obtaining the drive signal of the grid-connected converter through a voltage closed-loop controller and a pulse width modulator.

[0009] Further, when using the grid frequency observation value ω obtained by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, canceling the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop with the zeros of the active-power - frequency transfer function of the virtual synchronous generator includes: g * When using the grid frequency observation value ω obtained by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, the active power P output by the grid-connected converter

[0010] When using the grid frequency observation value ω obtained by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, the active power P output by the grid-connected converter g * When using the grid frequency observation value ω obtained by a low-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, the active power P output by the grid-connected converterout The transfer function with respect to the active power reference value P ref and the grid voltage angular frequency ω g is as follows:

[0011]

[0012] where J ω is the virtual moment of inertia; D ω is the virtual damping coefficient; ω 0 is the rated voltage angular frequency; K P is the power amplification coefficient, δ is the phase angle difference between the output voltage of the grid-connected converter and the grid voltage, E is the output voltage of the virtual synchronous generator, U g 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, according to the active loop transfer function of the virtual synchronous generator, adjust the bandwidth of the frequency-locked loop or the phase-locked loop, and take to make the poles of the equivalent closed-loop transfer function of the frequency-locked loop or the phase-locked loop can cancel out the zeros of the active-frequency transfer function of the virtual synchronous generator, and obtain the active output P out of the virtual synchronous generator after cancellation with respect to the active power reference value P ref and the grid voltage angular frequency ω g The transfer function is as follows:

[0014]

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

[0016] Furthermore, when using the value obtained by low-pass filtering the grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop as the feedforward value of the virtual synchronous generator frequency, it includes: by collecting the grid-connected voltage U pcc and current I pcc at the point of common coupling of the grid-connected converter, calculate the instantaneous active power P out injected into the grid by the grid-connected converter; subtract the instantaneous value P ref of the active power from the expected value P out of the active power to obtain ΔP; multiply ΔP by to obtain the virtual mechanical torque T m where ω 0 is the rated angular frequency of the grid; the virtual mechanical torque T m and the virtual damping torque T DAfter taking the difference, it passes through the virtual inertia control link and is multiplied to obtain the deviation frequency Δω, where the virtual torque T D is obtained by multiplying the deviation frequency Δω through the virtual damping control link and D ω J ω is the virtual moment of inertia, and D ω is the virtual damping coefficient; when a higher bandwidth is required for the frequency-locked loop or phase-locked loop, the value ω g * of the grid frequency observed by the frequency-locked loop or phase-locked loop after passing through the low-pass filter is used as the feed-forward value of the grid-connected converter frequency, where the equivalent closed-loop transfer function of the high-bandwidth frequency-locked loop or phase-locked loop can be expressed as The low-pass filter transfer function can be expressed as Γ 2 is the cut-off frequency of the high-bandwidth frequency-locked loop or phase-locked loop, and ω 1 is the cut-off frequency of the low-pass filter; the feed-forward value ω g * of the grid-connected converter frequency is added to the deviation frequency Δω to obtain the grid-connected converter frequency ω v ; the grid-connected converter frequency ω v is passed through an integration link to obtain the phase angle θ of the grid-connected converter output voltage; the given value of the grid-connected converter output voltage amplitude E is generated by the reactive power controller, and the given value of the grid-connected converter output voltage is obtained by integrating the amplitude E and phase angle θ of the grid-connected converter output voltage; 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 value of the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop after passing through the low-pass filter is used as the feed-forward value of the virtual synchronous generator frequency, the bandwidth Γ 2 of the frequency-locked loop or phase-locked loop is much higher than the bandwidth ω 1 of the low-pass filter, so that the pole of the low-pass filter is the dominant pole of the grid-connected converter frequency feed-forward transfer function and plays a dominant role.

[0018] Furthermore, when the value ω g * of the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop after passing through the low-pass filter is used as the feed-forward value of the grid-connected converter frequency and the pole of the low-pass filter cancels the zero point of the virtual synchronous generator active-frequency transfer function, it includes:

[0019] When the value ω g * of the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop after passing through the low-pass filter is used as the feed-forward value of the grid-connected converter frequency, the grid-connected converter output active power P outWith the active power reference value P ref and the 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, that is, Γ 2 is much greater than ω 1 , so the zero point -(Γ 2 +ω 1 ) approximately cancels out the value of the pole -Γ 2 , then:

[0022]

[0023] At this time, adjust the bandwidth of the low-pass filter, take so that the pole of the low-pass filter transfer function that plays a dominant role can cancel out the zero point of the active power-frequency transfer function of the virtual synchronous generator , and the output active power P of the virtual synchronous generator after cancellation is obtained out With the active power reference value P ref and the grid voltage angular frequency ω g The transfer function is:

[0024]

[0025] At this time, the active power-frequency transfer function of the virtual synchronous generator is Its steady-state output value under the step change of the grid frequency is zero, thus 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, and the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the virtual synchronous generator control method capable of improving power and frequency response as described in the first aspect is implemented.

[0027] In a third aspect, the present invention provides a computer device, including a memory and a processor. The processor and the memory communicate with each other. The memory stores program instructions executable by the processor, and the processor calls the program instructions to execute the virtual synchronous generator control method capable of improving power and frequency response as described in the first aspect.

[0028] Fourthly, the present invention provides an electronic device, including: 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 runs, the processor executes the computer program stored in the memory so that the electronic device executes instructions for implementing the virtual synchronous generator control method capable of improving power and frequency response as described in the first aspect.

[0029] Advantages of the present invention: It can eliminate the steady-state error of the active power regulation of the virtual synchronous generator. There is a differential term in the numerator of the active-frequency transfer function of the virtual synchronous generator, and the output active power can also damp the change of the grid frequency, thereby improving the effect of the virtual synchronous generator on the grid inertia support.

[0030] The advantages of the additional aspects of the present invention will be more clearly given in the following description part, or can be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a control structure block diagram of the virtual synchronous generator control method capable of improving power and frequency response according to the embodiments of the present invention.

[0033] Figure 2 It is a control block diagram of the virtual synchronous generator control method capable of improving power and frequency response according to Embodiment 1 of the present invention.

[0034] Figure 3 It is a control block diagram of the virtual synchronous generator control method capable of improving power and frequency response according to Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described through the drawings are exemplary and are only used to explain the present invention, and cannot be construed as a limitation to the present invention.

[0036] Those skilled in the art of the present technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art in the field to which the present invention belongs.

[0037] It should also be understood that terms such as those defined in a general dictionary should be understood as having a meaning consistent with their meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as here.

[0038] Those skilled in the art of the present technology can understand that, unless specifically stated otherwise, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the description of the present invention 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, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. Without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0040] For ease of understanding the present invention, the following further explains the present invention with specific embodiments in conjunction with the accompanying drawings, and 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 drawings are only schematic diagrams of the embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0042] Embodiment 1

[0043] In this Embodiment 1, first, a virtual synchronous generator control system is provided, including a controller configured to: use the grid frequency observed by a low-bandwidth frequency-locked loop and phase-locked loop as the feedforward value of the virtual synchronous generator frequency; wherein, 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 are cancelled with the zeros of the virtual synchronous generator active-frequency transfer function.

[0044] The common method is to introduce virtual inertia and virtual damping feedback into the system to form an inertia-damping comprehensive controller of the virtual synchronous generator, simulating the inertia-damping characteristics of the synchronous generator. The output power P of the virtual synchronous generator out can be expressed as:

[0045]

[0046] Among them, J ω is the virtual moment of inertia; D ω is the virtual damping coefficient; ω 0 is the rated voltage angular frequency; ω g is the grid voltage angular frequency; P ref is the active power reference command; K P is the power amplification coefficient, δ is the phase angle difference between the output voltage of the grid-connected converter and the grid voltage, E is the output voltage of the grid-connected converter, U g is the grid voltage, and X is the sum of the output impedance of the grid-connected converter and the impedance of the grid connection line. 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 , and the other is the power deviation D ω ω 0 (ω 0 -ω g ). It can be seen that when the system reaches the steady state, there is an error in the active power.

[0049] Combined with Figure 1 , Figure 2 As shown, to solve the above problems, in this embodiment, the above system is used to implement a virtual synchronous generator control method capable of improving power and frequency response, and the grid frequency observed by the low-bandwidth frequency-locked loop and phase-locked loop is used as the feedforward value of the virtual synchronous generator frequency. 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 with the zeros of the virtual synchronous generator active-power-frequency transfer function.

[0050] The specific steps are as follows:

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

[0052] 2) Subtract the instantaneous value P ref of the active power from the expected value P out of the active power to obtain ΔP;

[0053] 3) Multiply ΔP by to obtain the virtual mechanical torque T m , where ω 0is the rated angular frequency of the power grid;

[0054] 4) The virtual mechanical torque T m and the virtual damping torque T D are subtracted, and then multiplied by the virtual inertia control link and to obtain the deviation frequency Δω. Among them, the virtual damping torque T D is obtained by multiplying the deviation frequency Δω by the virtual damping control link and D ω ; J ω is the virtual moment of inertia, and D ω is the virtual damping coefficient;

[0055] 5) The grid frequency ω g * observed by the low-bandwidth frequency-locked loop or phase-locked loop is used as the feed-forward 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 Γ 1 is the cut-off frequency of the low-bandwidth frequency-locked loop or phase-locked loop;

[0056] 6) The feed-forward value ω g * of the grid-connected converter frequency is added to the deviation frequency Δω obtained in step 4) to obtain the grid-connected converter frequency ω v ;

[0057] 7) The grid-connected converter frequency ω v is integrated to obtain the phase angle θ of the grid-connected converter output voltage;

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

[0059] 9) The drive signal of 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 using the observed value ω g * of the grid frequency obtained by the low-bandwidth frequency-locked loop or phase-locked loop as the feed-forward value of the virtual synchronous generator frequency. According to Figure 2 the transfer function of the grid-connected converter output active power P out with the active power given value P ref and the grid voltage angular frequency ω g can be expressed as:

[0061]

[0062] Among them, J ωis the virtual moment of inertia; D ω is the virtual damping coefficient; ω 0 is the rated voltage angular frequency; E is the output voltage of the virtual synchronous generator, U g 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 time, adjust the bandwidth of the frequency-locked loop or the phase-locked loop, and take to make the equivalent closed-loop transfer function of the frequency-locked loop or the phase-locked loop The poles of can cancel out the zeros of the active-power - frequency transfer function of the virtual synchronous generator to obtain the output active power P of the virtual synchronous generator after cancellation out and the active power reference value P ref and the grid voltage angular frequency ω g The transfer function is:

[0064]

[0065] At this time, the active-power - frequency transfer function of the virtual synchronous generator is Its steady-state output value under a step change in the grid frequency is zero, thus eliminating the steady-state error of the active power regulation of the virtual synchronous generator. In addition, since there is a differential term in the numerator of this transfer function, the output active power can also damp the change in the grid frequency, thereby improving the effect of the virtual synchronous generator's inertia support for the grid.

[0066] Embodiment 2

[0067] Combined with Figure 1 、 Figure 3 As shown, a virtual synchronous generator control method provided in Embodiment 2 that can improve power and frequency response uses the value obtained by low-pass filtering the grid frequency observed by a high-bandwidth frequency-locked loop and phase-locked loop as the feedforward value of the virtual synchronous generator frequency. When using a high-bandwidth frequency-locked loop or phase-locked loop to obtain the grid frequency and perform low-pass filtering on its value for feedforward, the poles of the low-pass filter are cancelled out with the zeros of the active-power - frequency transfer function of the virtual synchronous generator. The specific steps are as follows:

[0068] 1) By collecting the grid-connected voltage U pcc 、current I pcc at the point of common coupling of the grid-connected converter, calculate the instantaneous active power P out injected into the grid by the grid-connected converter;

[0069] 2) Subtract the instantaneous value P of the active power ref from the expected value P out of the active power to obtain ΔP;

[0070] 3) ΔP and Multiply to obtain the virtual mechanical torque T m , where ω 0 is the rated angular frequency of the power grid;

[0071] 4) The virtual mechanical torque T m and the virtual damping torque T D are subtracted and then multiplied by through the virtual inertia control link to obtain the deviation frequency Δω, where the virtual damping torque T D is obtained by multiplying the deviation frequency Δω through the virtual damping control link and D ω , J ω is the virtual moment of inertia, and D ω is the virtual damping coefficient;

[0072] 5) When a high bandwidth is required for the frequency-locked loop or phase-locked loop, the value ω g * of the power grid frequency observed by the frequency-locked loop or phase-locked loop after passing through the low-pass filter is used as the feed-forward value of the grid-connected converter frequency, where the equivalent closed-loop transfer function of the high-bandwidth frequency-locked loop or phase-locked loop can be expressed as The low-pass filter transfer function can be expressed as Γ 2 is the cut-off frequency of the high-bandwidth frequency-locked loop or phase-locked loop, ω 1 is the cut-off frequency of the low-pass filter. At this time, the bandwidth Γ 2 of the frequency-locked loop or phase-locked loop is much higher than the bandwidth ω 1 of the low-pass filter, making the poles of the low-pass filter the dominant poles of the grid-connected converter frequency feed-forward transfer function and playing a dominant role;

[0073] 6) Add the feed-forward value ω g * of the grid-connected converter frequency to the deviation frequency Δω obtained in step 4) to obtain the frequency ω v of the grid-connected converter;

[0074] 7) Integrate the frequency ω v of the grid-connected converter to obtain the phase angle θ of the output voltage of the grid-connected converter;

[0075] 8) The given value of the amplitude E of the output voltage of the grid-connected converter is generated by the reactive power controller, and the amplitude E and phase angle θ of the output voltage of the grid-connected converter are integrated to obtain the given value of the output voltage of the grid-connected converter;

[0076] 9) Obtain the drive signal of the grid-connected converter through the voltage closed-loop controller and the pulse width modulator.

[0077] Figure 3The shown control block diagram 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 feed-forward value of the grid-connected converter frequency, according to Figure 3 the active power P output by the grid-connected converter can be obtained. out The transfer function of the active power given value P ref and the grid voltage angular frequency ω g 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 time, that is, Γ 2 is much larger than ω 1 , therefore, the zero point -(Γ 2 +ω 1 ) and the pole -Γ 2 are basically the same in value and approximately cancel each other out. It can be expressed as:

[0080]

[0081] At this time, adjust the bandwidth of the low-pass filter, take to make the pole of the dominant low-pass filter transfer function able to cancel the zero point of the active-frequency transfer function of the virtual synchronous generator , and obtain the output active power P of the virtual synchronous generator after cancellation out The transfer function of the active power given value P ref and the grid voltage angular frequency ω g is:

[0082]

[0083] At this time, the active-frequency transfer function of the virtual synchronous generator is Its steady-state output value under a step change in the grid frequency is zero, thus eliminating the steady-state error of the active power regulation of the virtual synchronous generator. In addition, since there is a differential term in the numerator of this transfer function, the output active power can also damp the change in the grid frequency, thereby improving the effect of the virtual synchronous generator's inertia support for the grid.

[0084] Example 3

[0085] This Example 3 provides a non-transitory computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the virtual synchronous generator control method capable of improving power and frequency response as described above is implemented. The method includes:

[0086] The value obtained by low-pass filtering the power grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop, or the power 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. When using the power 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 are cancelled with the zeros of the active-power - frequency transfer function of the virtual synchronous generator; when using the value obtained by low-pass filtering the power grid frequency obtained by a high-bandwidth frequency-locked loop or phase-locked loop as the feedforward, the poles of the low-pass filter are cancelled with the zeros of the active-power - frequency transfer function of the virtual synchronous generator.

[0087] Embodiment 4

[0088] Embodiment 4 of the present invention provides a computer device, including a memory and a processor, the processor and the memory communicate with each other, the memory stores program instructions executable by the processor, and the processor calls the program instructions to execute the virtual synchronous generator control method capable of improving power and frequency response as described above. The method includes:

[0089] The value obtained by low-pass filtering the power grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop, or the power 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. When using the power 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 are cancelled with the zeros of the active-power - frequency transfer function of the virtual synchronous generator; when using the value obtained by low-pass filtering the power grid frequency obtained by a high-bandwidth frequency-locked loop or phase-locked loop as the feedforward, the poles of the low-pass filter are cancelled with the zeros of the active-power - frequency transfer function of the virtual synchronous generator.

[0090] Embodiment 5

[0091] Embodiment 5 of the present invention provides an electronic device, including: 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 runs, the processor executes the computer program stored in the memory so that the electronic device executes the instructions for implementing the virtual synchronous generator control method capable of improving power and frequency response as described above. The method includes:

[0092] The value obtained by low-pass filtering the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop, or the grid frequency observed by a high-bandwidth frequency-locked loop or phase-locked loop, is used as the feed-forward value of the virtual synchronous generator frequency. When using the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop as the feed-forward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop are canceled with the zeros of the active-frequency transfer function of the virtual synchronous generator; when using the value obtained by low-pass filtering the grid frequency obtained by a high-bandwidth frequency-locked loop or phase-locked loop as the feed-forward, the poles of the low-pass filter are canceled with the zeros of the active-frequency transfer function of the virtual synchronous generator.

[0093] Those skilled in the art should understand that the 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 complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented 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] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0095] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implements the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device, and a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide means for implementing the specified functions in Figure 1 one process or multiple processes and / or blocksFigure 1 Steps of functions specified in one or more boxes.

[0097] Although the specific implementation manners of the present invention have been described in conjunction with the accompanying drawings, they are not limitations on the protection scope 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 deformations that can be made by those skilled in the art without creative efforts should be covered within the protection scope of the present invention.

Claims

1. A virtual synchronous generator control method, characterized in that: include: The grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop or the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop is used as a feedforward value of the virtual synchronous generator frequency after low-pass filtering; Among them, when the grid frequency observed by a low-bandwidth frequency-locked loop or phase-locked loop is used as feedforward, the poles of the equivalent closed-loop transfer function of the frequency-locked loop or phase-locked loop are canceled with the zeros of the active power-frequency transfer function of the virtual synchronous generator; when the grid frequency is obtained by using a high-bandwidth frequency-locked loop or phase-locked loop and its low-pass filtered value is used as feedforward, the poles of the low-pass filter are canceled with the zeros of the active power-frequency transfer function of the virtual synchronous generator.

2. The virtual synchronous generator control method according to claim 1, characterized in that: When the grid frequency observed by the low-bandwidth frequency-locked loop or phase-locked loop is used as the feedforward value of the virtual synchronous generator frequency, it includes: collecting the grid voltage U of 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 ; The expected value of active power P ref and instantaneous active power value P out The difference is obtained by ΔP, and the virtual mechanical torque T is obtained by multiplying ΔP by the inverse of the rated angular frequency of the power grid. m ; Virtual mechanical torque T m With virtual damping torque T D After making the difference, the virtual inertia control link is used to Multiply to get the deviation frequency Δω, where the virtual damping torque T D The deviation frequency Δω is controlled by the virtual damping link and D ω Multiply them together to get J ω is the virtual moment of inertia, D ω is the virtual damping coefficient; 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 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, s is the Laplace operator; the feedforward value ω of the grid-connected converter frequency g * Adding the deviation frequency Δω to obtain the frequency ω of the grid-connected converter v ; Set the frequency of the grid-connected converter ω v The phase angle θ of the grid-connected converter output voltage is obtained after the integration link; the given value of the grid-connected converter output voltage amplitude E is generated by the reactive power controller, and the given value of the grid-connected converter output voltage is obtained by integrating the amplitude E and the phase angle θ of the grid-connected converter output voltage; the driving 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 1, characterized in that: The grid frequency observation value ω obtained by the low-bandwidth frequency-locked loop or phase-locked loop g * When used as the feedforward value of the virtual synchronous generator frequency, the poles of the frequency-locked loop or phase-locked loop equivalent closed-loop transfer function are canceled with the zeros of the virtual synchronous generator active power-frequency transfer function, including: The grid frequency observation value ω obtained by the low-bandwidth frequency-locked loop or phase-locked loop g * When used as the feedforward value of the virtual synchronous generator frequency, the grid-connected converter outputs active power P out With active power given value P ref and grid voltage angular frequency ω g The transfer function is: Among them, J ω is the virtual moment of inertia; D ω is the virtual damping coefficient; ω0 is the rated voltage angular frequency; K P is the power amplification factor, δ is the phase angle difference between the grid-connected converter output voltage and the grid voltage, E is the virtual synchronous generator output voltage, U g is the grid voltage, and X is the sum of the virtual synchronous generator output impedance and the grid connection line impedance.

4. The virtual synchronous generator control method according to claim 3, characterized in that: According to the transfer function of the active loop of the virtual synchronous generator, adjust the bandwidth of the frequency-locked loop or phase-locked loop to obtain Make the frequency-locked loop or phase-locked loop equivalent to the closed-loop transfer function The poles of the virtual synchronous generator can be compared with the active power-frequency transfer function The zero point cancellation of the virtual synchronous generator is obtained after the cancellation of the active output P out With active power given value P ref and grid voltage angular frequency ω g The transfer function is: At this time, the active power-frequency transfer function is Its steady-state output value under a step change in grid frequency is zero, 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 the grid frequency observed by a high-bandwidth frequency-locked loop or a phase-locked loop is used as the feedforward value of the virtual synchronous generator frequency through a low-pass filter, the method includes: collecting the grid voltage U of 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 ; The expected value of active power P ref and the instantaneous value of active power P out Difference, get ΔP; ΔP and Multiply to get the virtual mechanical torque T m , where ω0 is the rated angular frequency of the power grid; the virtual mechanical torque T m With virtual damping torque T D After making the difference, the virtual inertia control link is used to Multiply to get the deviation frequency Δω, where the virtual torque T D The deviation frequency Δω is controlled by the virtual damping link and D ω Multiply them together to get J ω is the virtual moment of inertia, D ω is the virtual damping coefficient; when the frequency-locked loop or phase-locked loop requires a higher bandwidth, the value ω after the grid frequency observed by the frequency-locked loop or phase-locked loop passes 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 low-pass filter transfer function can be expressed as Γ2 is the high-bandwidth frequency-locked loop or phase-locked loop cutoff frequency, ω1 is the low-pass filter cutoff frequency; the feedforward value ω of the grid-connected converter frequency is g * Adding the deviation frequency Δω to obtain the frequency ω of the grid-connected converter v ; Set the frequency of the grid-connected converter ω v The phase angle θ of the grid-connected converter output voltage is obtained after the integration link; the given value of the grid-connected converter output voltage amplitude E is generated by the reactive power controller, and the given value of the grid-connected converter output voltage is obtained by integrating the amplitude E and the phase angle θ of the grid-connected converter output voltage; the driving 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 or phase-locked loop is used as the feedforward value of the virtual synchronous generator frequency after low-pass filtering, the bandwidth of the frequency-locked loop or phase-locked loop Γ2 is much higher than the bandwidth of the low-pass filter ω1, so that the pole of the low-pass filter is the grid-connected converter frequency feedforward transfer function The dominant pole plays a leading role.

7. The virtual synchronous generator control method according to claim 1, characterized in that: The value ω after the grid frequency observed by the high-bandwidth frequency-locked loop or phase-locked loop passes through the low-pass filter g * As the feedforward value of the grid-connected converter frequency, when the pole of the low-pass filter is offset with the zero of the active power-frequency transfer function of the virtual synchronous generator, it includes: The value ω after the high-bandwidth frequency-locked loop or phase-locked loop observes the frequency of the power grid through a low-pass filter g * When used as the feedforward value of the grid-connected converter frequency, the grid-connected converter outputs active power P out With active power given value P ref and grid voltage angular frequency ω g 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, that is, Γ2 is much larger than ω1, the values ​​of the zero point -(Γ2+ω1) and the pole point -Γ2 approximately cancel each other out, then: At this time, adjust the bandwidth of the low-pass filter to The dominant low-pass filter transfer function The poles of the virtual synchronous generator can be compared with the active power-frequency transfer function The zero point cancellation of the virtual synchronous generator is obtained after the cancellation. out With active power given value P ref and grid voltage angular frequency ω g The transfer function is: At this time, the active power-frequency transfer function of the virtual synchronous generator is: Its steady-state output value under a step change in grid frequency is zero, 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, and when the computer instructions are executed by a processor, the virtual synchronous generator control method according to any one of claims 1 to 6 is implemented.

9. A computer device, characterized in that: It includes a memory and a processor, the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls 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: 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 so that the electronic device executes instructions for implementing the virtual synchronous generator control method as described in any one of claims 1-6.

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