Virtual synchronous generator fast power control method and system

Abstract

This invention discloses a fast power control method and system for a virtual synchronous generator, belonging to the field of distributed generation inverter control and power electronics technology. The topology of the virtual synchronous generator using this control method includes a DC-side voltage source, a three-phase full-bridge inverter circuit, a three-phase LC filter, three-phase line impedance, and a three-phase power grid. The control method includes virtual synchronous generator control and pre-filter control, which can effectively improve the active power control bandwidth of the virtual synchronous generator without affecting its grid-connected stability.

Description

Technical Field

[0001] This invention belongs to the field of distributed generation inverter control and power electronics technology, and relates to a fast power control method for a virtual synchronous generator. The control method includes virtual synchronous generator control and pre-filter control, which can effectively improve the active power control bandwidth of the virtual synchronous generator without affecting the grid connection stability of the virtual synchronous generator. Background Technology

[0002] Current-controlled grid-connected inverters have been widely used in distributed generation based on renewable energy sources due to their advantages such as fast output power regulation, high MPPT efficiency, and high renewable energy utilization. However, current-controlled grid-connected inverters generally prioritize maximizing active power output and cannot support grid voltage and frequency stability like traditional synchronous generators, which can easily lead to instability issues. With the increasing penetration rate of renewable energy generation, the power grid is gradually exhibiting weak or even extremely weak grid conditions. The stability of grid-connected inverters connected to weak grids has received increasing attention, leading to the development of virtual synchronous generator technology.

[0003] Virtual synchronous generator (VSR) technology can simulate the damping and inertia of traditional synchronous machines, thereby providing frequency and voltage support for the power grid. Existing research shows that when large-scale renewable energy generation equipment is connected to the grid, connecting a certain proportion of VSRs is beneficial to the stability of distributed generation systems. Furthermore, unlike current-controlled grid-connected inverters, VSRs are based on voltage control and exhibit strong stability even in weak or extremely weak power grids.

[0004] However, the active power control bandwidth of virtual synchronous generators is much lower than that of current-controlled grid-connected inverters, and their active power regulation time can even be as long as several seconds, making it difficult to meet the grid standard's requirements for the speed of automatic generation control (AGC) of new energy sources.

[0005] Therefore, it is of great significance to improve the active power control bandwidth of the virtual synchronous generator without affecting its stability and to achieve fast power control.

[0006] Currently, several academic papers have analyzed and proposed solutions for fast power control of inverters, such as:

[0007] 1. An article titled "Adaptive Fast Power Control Strategy for Voltage-Controlled Inverters in Weak Grids," published in the *Journal of Power Supply*, was first published online on July 4, 2022. This paper studies a fast power control strategy for droop-controlled inverters. However, droop control cannot simulate the damping and inertia of traditional synchronous machines, resulting in insufficient support for the stability of weak grids. Therefore, it is necessary to consider a fast power control method using virtual synchronous generators. However, droop-controlled inverters have simple power loop parameters, consisting only of the droop coefficient, making them first-order systems; while virtual synchronous generator control includes a virtual moment of inertia J, making it a second-order system. The fast power control strategy proposed in this paper is difficult to apply to virtual synchronous generators.

[0008] 2. Chinese invention patent document (publication number CN 108390396 A), published on August 10, 2018, entitled "Control Method of Virtual Synchronous Generator Based on Dynamic Virtual Reactor," proposes a control method for a virtual synchronous generator based on dynamic virtual reactance. This method designs virtual reactance in a two-phase rotating coordinate system to reduce the coupling between the active and reactive power output of the virtual synchronous generator during dynamic processes, thereby suppressing power oscillations. However, although the dynamic virtual reactance proposed in this patent can improve stability, it actually reduces the active power control bandwidth.

[0009] 3. An article titled "Novel PLL Parameter Design for Fast Power Control of Photovoltaics," *Power Electronics Technology*, Vol. 56, No. 4, 2022, pp. 102-108. This article proposes a novel PLL design method that improves the dynamic performance of the PLL. Unlike traditional design methods, two real poles are introduced in the loop filter design. Through effective design of the system zero-point positions, slow dynamics of the system are eliminated, improving the dynamic performance and thus facilitating the participation of grid-connected photovoltaic systems in system frequency regulation. However, this method is applicable to current-controlled grid-connected inverters and suffers from stability issues under weak grid conditions.

[0010] Based on the above literature, existing methods for stable operation of virtual synchronous generators under strong grid conditions have the following shortcomings:

[0011] 1. Existing fast power control methods are mainly for droop-controlled inverters or current-controlled grid-connected inverters, rather than for virtual synchronous generators. The power loop of virtual synchronous generators is more complex, and the above methods are difficult to use to solve the fast power control problem of virtual synchronous generators.

[0012] 2. Existing virtual impedance-based methods can improve the stability of virtual synchronous generators, but they can reduce the active power control bandwidth of virtual synchronous generators.

[0013] Therefore, it is necessary to study a fast power control method for virtual synchronous generators that does not affect stability. Summary of the Invention

[0014] The problem this invention aims to solve is the inability to simultaneously address the complexity of control, stability issues, and the inability to balance the active power control bandwidth of virtual synchronous generators with those of non-virtual synchronous generators in existing technologies. Specifically, it proposes a fast power control method and system for virtual synchronous generators. This control method achieves fast power control of the virtual synchronous generator through virtual synchronous generator control and pre-filter control. It can improve the active power control bandwidth of the virtual synchronous generator without affecting its stability.

[0015] The objective of this invention is achieved as follows: This invention provides a fast power control method for a virtual synchronous generator. The topology of the virtual synchronous generator using this control method includes an inverter, a three-phase LC filter, and a three-phase grid impedance connected in sequence, with the three-phase grid impedance connected to the three-phase grid.

[0016] In each inverter calculation cycle T c。mpute Each round of control calculation is performed, and the steps of the round of control calculation are as follows:

[0017] S1, the capacitor and inductor in the three-phase LC filter are denoted as the filter capacitor and filter inductor, respectively, and the three-phase filter voltage U of the filter capacitor is sampled. a U b U c The three-phase filter current I of the filter inductor La I Lb I Lc ;

[0018] S2, for the three-phase filter voltage U a U b U c and three-phase filter current I La I Lb I Lc The two-phase filter voltage U is obtained by transforming the three-phase stationary coordinate system to a two-phase stationary coordinate system. α U β and two-phase filter current I Lα I Lβ ;

[0019] S3, based on the two-phase filter voltage U α U β and two-phase filter current I Lα I Lβ The inverter's output active power P and inverter's output reactive power Q are calculated using the instantaneous power calculation formula.

[0020] S4, based on the phase angle θ of the filter capacitor A phase voltage obtained from the previous round of control calculations. PLL_Last For the two-phase filter voltage Uα U β The d-axis filtered voltage U is obtained by transforming the two-phase stationary coordinate system to the two-phase rotating coordinate system. d and q-axis filter voltage U q , where the q-axis is the reactive axis and the d-axis is the active axis;

[0021] S5, based on the q-axis filter voltage U q The phase angle θ of the phase-locked loop voltage of phase A of the filter capacitor is calculated using the phase-locked loop formula in a single synchronous coordinate system. PLL The phase angle θ of phase A voltage of the filter capacitor PLL Used for control calculations in the next round;

[0022] S6, based on the reactance value X of the three-phase power grid impedance. g The original reference value P of the inverter output active power set The rated angular frequency ω of a three-phase power grid n and the rated phase voltage amplitude U of the three-phase power grid nAmp The actual reference value P of the inverter output active power is obtained by calculating the formula of the pre-filter. give ;

[0023] S7, based on the inverter output active power P and the actual reference value P of the inverter output active power. give The modulation angle θ of the virtual synchronous generator output is calculated using the active power loop calculation formula. m ;

[0024] S8, based on the inverter output reactive power Q and d-axis filter voltage U d The modulation amplitude U of the virtual synchronous generator output is calculated using the reactive power loop calculation formula. m_VSG ;

[0025] S9, based on the modulation amplitude value U output by the virtual synchronous generator. m_VSG The modulation wave angle θ output by the virtual synchronous generator m The three-phase modulation voltage U output by the virtual synchronous generator is calculated using the virtual synchronous generator modulation voltage calculation formula. mA U mB U mC ;

[0026] S10, the three-phase modulated voltage U output by the virtual synchronous generator. mA U mB U mC SVPWM modulation is performed to generate switching signals for the inverter power devices.

[0027] Preferably, the instantaneous power calculation formula is:

[0028] P = Uα I Lα +U β I Lβ

[0029] Q = U β I Lα -U α I Lβ .

[0030] Preferably, the two-phase filter voltage U α U β The d-axis filtered voltage U is obtained by transforming the two-phase stationary coordinate system to the two-phase rotating coordinate system. d and q-axis filter voltage U q The transformation formula is:

[0031] U d =cos(θ) PLL_Last )×U α +sin(θ PLL_Last )×U β

[0032] U q = -sin(θ) PLL_Last )×U α +cos(θ PLL_Last )×U β .

[0033] Preferably, the phase-locked loop formula for the single synchronous coordinate system phase-locked loop is:

[0034]

[0035] Where, k p_PLL k is the proportional regulator coefficient of the single synchronous coordinate system phase-locked loop. i_PLL is the integral regulator coefficient of the single synchronous coordinate system phase-locked loop, and s is the Laplace operator.

[0036] Preferably, the formula for calculating the pre-filter is:

[0037]

[0038] Where, τ ref For the desired time constant of fast power control, D p denoted as the frequency droop coefficient of the virtual synchronous generator, J as the virtual moment of inertia of the virtual synchronous generator, and s as the Laplace operator.

[0039] Preferably, the active power loop calculation formula is as follows:

[0040]

[0041] Among them, Dp denoted as the frequency droop coefficient of the virtual synchronous generator, J as the virtual moment of inertia of the virtual synchronous generator, and s as the Laplace operator.

[0042] Preferably, the reactive power loop calculation formula is as follows:

[0043]

[0044] Among them, Q set D is the reference value for the reactive power output of the inverter. q K is the voltage droop factor of the virtual synchronous generator. q is the reactive power control inertia coefficient, and s is the Laplace operator.

[0045] Preferably, the formula for calculating the modulation voltage of the virtual synchronous generator is:

[0046] U mA =U m_VSG ×cos(θ m )

[0047]

[0048]

[0049] The present invention also provides a fast power control system for a virtual synchronous generator, comprising:

[0050] Used to obtain the three-phase filter voltage U a U b U c and three-phase filter current I La I Lb I Lc The sampling module;

[0051] Used for filtering three-phase voltage U a U b U c and three-phase filter current I La I Lb I Lc A control module for transforming a three-phase stationary coordinate system into a two-phase stationary coordinate system;

[0052] Used to determine the two-phase filter voltage U α U β and two-phase filter current I Lα I Lβ The calculation module calculates the inverter's output active power P and inverter's output reactive power Q using the instantaneous power calculation formula.

[0053] The phase angle θ of the filter capacitor A phase voltage obtained from the previous round of control calculation is used to extract the phase angle θ of the filter capacitor A phase voltage.PLL_Last And the two-phase filter voltage U α U β The d-axis filtered voltage U is obtained by transforming the two-phase stationary coordinate system to the two-phase rotating coordinate system. d and q-axis filter voltage U q The control module;

[0054] Used to filter voltage U along the q-axis q The phase angle θ of the phase-locked loop voltage of phase A of the filter capacitor is calculated using the phase-locked loop formula in a single synchronous coordinate system. PLL The calculation module;

[0055] Used to determine the reactance value X based on the impedance of the three-phase power grid. g The original reference value P of the inverter output active power set The rated angular frequency ω of a three-phase power grid n and the rated phase voltage amplitude U of the three-phase power grid nAmp The actual reference value P of the inverter output active power is obtained by calculating the formula of the pre-filter. give The calculation module;

[0056] Used to determine the inverter's output active power P and the actual reference value P of the inverter's output active power. give The modulation angle θ of the virtual synchronous generator output is calculated using the active power loop calculation formula. m The calculation module;

[0057] Used to determine the inverter output reactive power Q and d-axis filter voltage U d The modulation amplitude U of the virtual synchronous generator output is calculated using the reactive power loop calculation formula. m _ VSG The calculation module;

[0058] Used to determine the modulation amplitude U output by the virtual synchronous generator m_VSG The modulation wave angle θ output by the virtual synchronous generator m The three-phase modulation voltage U output by the virtual synchronous generator is calculated using the virtual synchronous generator modulation voltage calculation formula. mA U mB U mC The calculation module;

[0059] The three-phase modulation voltage U used to modulate the output of the virtual synchronous generator mA U mB U mC A control module that performs SVPWM modulation to generate switching signals for the inverter power devices;

[0060] The module and microprocessor are programmed or configured to perform the steps of the fast power control method for the virtual synchronous generator according to any one of claims 1 to 8.

[0061] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program programmed or configured to perform the fast power control method for a virtual synchronous generator according to any one of claims 1 to 8.

[0062] Compared to existing technologies, the virtual synchronous generator fast power control method proposed in this invention improves the control bandwidth by adding a leading pre-filter to the active power reference value input channel, thereby modifying the original active power reference value. Furthermore, since the pre-filter and the original system are connected in series, as long as both are designed stably, the pre-filter does not affect control stability. For synchronous generators, this invention considers the virtual moment of inertia J and proposes a calculation formula for its pre-filter.

[0063] Specifically, the beneficial effects of the present invention are as follows:

[0064] 1. This invention considers the problem of fast power control of virtual synchronous generators and proposes a fast power control method for virtual synchronous generators based on a pre-filter;

[0065] 2. This invention considers the inertia coefficient J of the virtual synchronous generator and provides a design method for the pre-filter considering the virtual inertia J.

[0066] 3. Existing inverter fast power control is mainly for droop control inverters or current control grid-connected inverters, not for virtual synchronous generators. The power loop of virtual synchronous generators is more complex, and the above methods are difficult to use to solve the problem of fast power control of virtual synchronous generators. Attached Figure Description

[0067] Figure 1 The diagram shows the main circuit topology of a virtual synchronous generator using the control method of this invention.

[0068] Figure 2 This is a control block diagram of a virtual synchronous generator that relates to the control method of the present invention.

[0069] Figure 3 This is a block diagram of the pre-filter control method relating to the present invention.

[0070] Figure 4 The virtual synchronous generator grid connection waveform is shown when the control method of this invention is not used.

[0071] Figure 5 The waveform of the virtual synchronous generator when using the control method of the present invention is shown. Detailed Implementation

[0072] The following is a detailed description of this embodiment with reference to the accompanying drawings.

[0073] Figure 1 The main circuit topology of the virtual synchronous generator using this control method is shown below. Figure 1 As can be seen, the topology of the virtual synchronous generator using this control method includes an inverter, a three-phase LC filter, and a three-phase grid impedance connected in sequence, with the three-phase grid impedance connected to the three-phase grid.

[0074] exist Figure 1 In the diagram above, 10 represents the DC power supply, 20 represents the inverter, 30 represents the three-phase LC filter, 40 represents the three-phase line impedance, and 50 represents the three-phase power grid. The DC voltage source 10 is connected to the three-phase full-bridge inverter circuit 20, which is then connected to the three-phase power grid 50 via the three-phase LC filter 30 and the three-phase power grid impedance 40. dc L is the DC side voltage of DC side voltage source 10. f C is the filter inductor in the three-phase LC filter 30. f R is the filter capacitor in the three-phase LC filter 30. g For the resistance in a three-phase power grid with an impedance of 40Ω, L g Grid represents the inductance in a three-phase power grid impedance of 40, Grid represents a three-phase power grid impedance of 50, and PCC is the common coupling point.

[0075] In this embodiment, the main circuit parameters of the inverter are: DC side voltage V dc The inverter's rated output line voltage is 380V / 50Hz, its rated power is 20kW, and the filter capacitor C is 750V. f The value is 11.6uF, and the inverter-side damping resistor R d The value is 2.1811Ω, and the filter inductance L f The value is 0.9mH, and the inductance value L in the three-phase power grid impedance is... g =15mH, the resistance value R in a three-phase power grid g =0.5Ω. In this embodiment, the inverter is a three-phase full-bridge inverter circuit.

[0076] Figure 2 This is a control block diagram of the virtual synchronous generator relating to the present invention; Figure 3 This is a block diagram of the pre-filter control method according to the present invention. The steps of the control method described in the present invention are as follows:

[0077] In each inverter calculation cycle T compute Each round of control calculation is performed, and the steps of the round of control calculation are as follows:

[0078] Step 1: Denote the capacitor and inductor in the three-phase LC filter as the filter capacitor and filter inductor, respectively, and sample the three-phase filter voltage U of the filter capacitor. a U b U c The three-phase filter current I of the filter inductor La I Lb L Lc ;

[0079] Step 2, adjust the three-phase filter voltage U a U b U c and three-phase filter current I La I Lb L Lc The two-phase filter voltage U is obtained by transforming the three-phase stationary coordinate system to a two-phase stationary coordinate system. α U β and two-phase filter current I Lα I Lβ .

[0080] In this embodiment, the transformation formulas are as follows:

[0081]

[0082]

[0083] Step 3, based on the two-phase filter voltage U α U β and two-phase filter current I Lα I Lβ The inverter's output active power P and inverter's output reactive power Q are calculated using the instantaneous power calculation formula.

[0084] In this embodiment, the instantaneous power calculation formula is:

[0085] P = U α I Lα +U β I Lβ

[0086] Q = U β L Lα -U α I Lβ

[0087] Step 4: Based on the phase angle θ of the filter capacitor A phase voltage obtained from the previous control calculation... PLL_Last For the two-phase filter voltage U α U β The d-axis filtered voltage U is obtained by transforming the two-phase stationary coordinate system to the two-phase rotating coordinate system. d and q-axis filter voltage Uq , where the q-axis is the reactive axis and the d-axis is the active axis.

[0088] In this embodiment, the transformation is as follows:

[0089] U d =cos(θ) PLL_Last )×U α +sin(θ PLL_Last )×U β

[0090] U q = -sin(θ) PLL_Last )×U α +cos(θ PLL_Last )×U β .

[0091] Step 5, based on the q-axis filter voltage U q The phase angle θ of the phase-locked loop voltage of phase A of the filter capacitor is calculated using the phase-locked loop formula in a single synchronous coordinate system. PLL The phase angle θ of phase A voltage of the filter capacitor PLL Used for control calculations in the next round.

[0092] In this embodiment, the phase-locked loop formula for the single synchronous coordinate system is:

[0093]

[0094] Where, k p_PLL k is the proportional regulator coefficient of the single synchronous coordinate system phase-locked loop. i_PLL is the integral regulator coefficient of the single synchronous coordinate system phase-locked loop, and s is the Laplace operator.

[0095] Step 6, based on the reactance value X of the three-phase power grid impedance. g The original reference value P of the inverter output active power set The rated angular frequency ω of a three-phase power grid n and the rated phase voltage amplitude U of the three-phase power grid nAmp The actual reference value P of the inverter output active power is obtained by calculating the formula of the pre-filter. give .

[0096] In this embodiment, the formula for calculating the pre-filter is:

[0097]

[0098] Where, τ ref For the desired time constant of fast power control, D p denoted as the frequency droop coefficient of the virtual synchronous generator, J as the virtual moment of inertia of the virtual synchronous generator, and s as the Laplace operator.

[0099] Step 7, based on the inverter output active power P and the actual reference value P of the inverter output active power. give The modulation angle θ of the virtual synchronous generator output is calculated using the active power loop calculation formula. m .

[0100] In this embodiment, the active power loop calculation formula is:

[0101]

[0102] Among them, D p denoted as the frequency droop coefficient of the virtual synchronous generator, J as the virtual moment of inertia of the virtual synchronous generator, and s as the Laplace operator.

[0103] Step 8, based on the inverter output reactive power Q and d-axis filter voltage U d The modulation amplitude U of the virtual synchronous generator output is calculated using the reactive power loop calculation formula. m_VSG .

[0104] In this embodiment, the reactive power loop calculation formula is as follows:

[0105]

[0106] Among them, Q set D is the reference value for the reactive power output of the inverter. q K is the voltage droop factor of the virtual synchronous generator. q is the reactive power control inertia coefficient, and s is the Laplace operator.

[0107] Step 9, based on the modulation amplitude value U output by the virtual synchronous generator m_VSG The modulation wave angle θ output by the virtual synchronous generator m The three-phase modulation voltage U output by the virtual synchronous generator is calculated using the virtual synchronous generator modulation voltage calculation formula. mA U mB U mC .

[0108] In this embodiment, the formula for calculating the modulation voltage of the virtual synchronous generator is:

[0109] U mA =U m_VSG ×cos(θ m )

[0110]

[0111]

[0112] Step 10, modulate the three-phase modulation voltage U output by the virtual synchronous generator. mA U mB U mC SVPWM modulation is performed to generate switching signals for the inverter power devices.

[0113] In this embodiment, the control parameter is: the inverter calculation frequency f. compute =16000Hz, inverter calculation period T compute =1 / f compute Fast power control desired time constant τ ref The proportional regulator coefficient k of the single synchronous coordinate system phase-locked loop is 0.02s. p _ PLL =1.0637, the integral regulator coefficient k of the single synchronous coordinate system phase-locked loop. i_PLL =176.0135; Inverter output active power original reference value P set =20kW, rated angular frequency ω of three-phase power grid n = 314.1593 rad / s, reactance value X of the three-phase power grid impedance g =ω n L g Virtual synchronous generator frequency droop coefficient D p =10, Virtual synchronous generator virtual moment of inertia J = 0.057 kg × m 2 The rated phase voltage amplitude U of a three-phase power grid nAmp =311.08V, inverter output reactive power reference value Q set =0Var, Virtual synchronous generator voltage droop coefficient D q =642, reactive power control inertia coefficient K q =14.2.

[0114] Figure 4 The virtual synchronous generator grid connection waveform when the control method of this invention is not used. Figure 5 This is the virtual synchronous generator grid-connected waveform when the control method of this invention is used. Figure 4 and Figure 5 As can be seen from the comparison, the sampling control method of the present invention significantly improves the grid-connected waveform of the virtual synchronous generator.

[0115] The present invention also provides a fast power control system for a virtual synchronous generator, comprising:

[0116] Used to obtain the three-phase filter voltage U a U b U c and three-phase filter current I La I Lb I LcThe sampling module;

[0117] Used for filtering three-phase voltage U a U b U c and three-phase filter current I La I Lb I Lc A control module for transforming a three-phase stationary coordinate system into a two-phase stationary coordinate system;

[0118] Used to determine the two-phase filter voltage U α U β and two-phase filter current I Lα I Lβ The calculation module calculates the inverter's output active power P and inverter's output reactive power Q using the instantaneous power calculation formula.

[0119] The phase angle θ of the filter capacitor A phase voltage obtained from the previous round of control calculation is used to extract the phase angle θ of the filter capacitor A phase voltage. PLL_Last And the two-phase filter voltage U α U β The d-axis filtered voltage U is obtained by transforming the two-phase stationary coordinate system to the two-phase rotating coordinate system. d and q-axis filter voltage U q The control module;

[0120] Used to filter voltage U along the q-axis q The phase angle θ of the phase-locked loop voltage of phase A of the filter capacitor is calculated using the phase-locked loop formula in a single synchronous coordinate system. PLL The calculation module;

[0121] Used to determine the reactance value X based on the impedance of the three-phase power grid. g The original reference value P of the inverter output active power set The rated angular frequency ω of a three-phase power grid n and the rated phase voltage amplitude U of the three-phase power grid nAmp The actual reference value P of the inverter output active power is obtained by calculating the formula of the pre-filter. give The calculation module;

[0122] Used to determine the inverter's output active power P and the actual reference value P of the inverter's output active power. give The modulation angle θ of the virtual synchronous generator output is calculated using the active power loop calculation formula. m The calculation module;

[0123] Used to determine the inverter output reactive power Q and d-axis filter voltage U d The modulation amplitude U of the virtual synchronous generator output is calculated using the reactive power loop calculation formula. m_VSG The calculation module;

[0124] Used to determine the modulation amplitude U output by the virtual synchronous generator m_VSG The modulation wave angle θ output by the virtual synchronous generator m The three-phase modulation voltage U output by the virtual synchronous generator is calculated using the virtual synchronous generator modulation voltage calculation formula. mA U mB U mC The calculation module;

[0125] The three-phase modulation voltage U used to modulate the output of the virtual synchronous generator mA U mB U mC A control module that performs SVPWM modulation to generate switching signals for the inverter power devices;

[0126] The module and microprocessor are programmed or configured to perform the steps of the fast power control method for the virtual synchronous generator according to any one of claims 1 to 8.

[0127] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program programmed or configured to perform the fast power control method for a virtual synchronous generator according to any one of claims 1 to 8.

[0128] The circuit topology and control method of the present invention described above can be viewed as a hardware embodiment of the circuit topology alone, a software embodiment consisting only of the control method, or a combined hardware and software implementation based on the control method of the circuit topology and modules. Furthermore, the control method portion of the present invention can be 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, appearing in the form of a computer program product; and can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0129] Furthermore, embodiments of the present invention are described in conjunction with flowcharts and / or block diagrams, and should be understood to mean that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts 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 flowcharts of the present invention. Figure 1 One or more processes and / or boxes Figure 1The means specifying the functions in one or more boxes. These computer program instructions may also be stored in a computer-readable storage medium capable of directing 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 implemented in the process of the invention. Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process of the present invention. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0130] Therefore, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any changes and modifications made by those skilled in the art based on the specific embodiments of the present invention and the above circumstances should be considered as equivalent solutions of this application and should fall within the protection scope of the present invention.

Claims

1. A method of fast power control for a virtual synchronous generator, the topology of the virtual synchronous generator to which the method is applied comprising an inverter, a three-phase LC filter and a three-phase grid impedance connected in series, the three-phase grid impedance being connected to a three-phase grid; characterized in that At each inverter calculation cycle A round of control calculations is performed, the steps of which are as follows: S1, the capacitance and inductance in the three-phase LC filter are respectively recorded as filter capacitance and filter inductance, and the three-phase filter voltage of the filter capacitance is sampled and the three-phase filter current of the filter inductance ; S2, a three-phase filtered voltage and a three-phase filtered current performing a transformation from a three-phase stationary coordinate system to a two-phase stationary coordinate system to obtain a two-phase filtered voltage and a two-phase filtered current ; S3, the two-phase filtered voltage and the two-phase filtered current , the inverter output active power P and the inverter output reactive power Q are calculated by the instantaneous power calculation formula S4, the filtered A-phase voltage phase angle calculated according to the control of the previous round , the two-phase filtered voltage is transformed from the two-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the d-axis filtered voltage and the q-axis filtered voltage , wherein the q-axis is the reactive axis and the d-axis is the active axis; S5, the q-axis filter voltage The filter capacitor A-phase voltage phase angle is calculated by a single synchronous coordinate system phase-locked loop phase-locked formula The filter capacitor A-phase voltage phase angle for the control calculation of the next round; S6, the reactance value of the three-phase power grid impedance , the original reference value of the inverter output active power , the rated angular frequency of the three-phase power grid , and the rated phase voltage amplitude of the three-phase power grid , the actual reference value of the inverter output active power is calculated by a calculation formula of the pre-filter ; the pre-filter calculation formula being: wherein is a desired time constant for fast power control, is a virtual synchronous generator frequency droop coefficient, is a virtual synchronous generator virtual moment of inertia, is a Laplacian operator; S7, calculating the modulation wave angle of the virtual synchronous generator output by the active power loop calculation formula according to the active power output by the inverter P and the actual reference value of the active power output by the inverter ;​ S8, calculating the modulation wave amplitude of the virtual synchronous generator output by the reactive power loop calculation formula , according to the reactive power Q and the d-axis filter voltage output by the inverter ; S9, a modulation wave amplitude value output by the virtual synchronous generator and a modulation wave angle output by the virtual synchronous generator , a three-phase modulation voltage output by the virtual synchronous generator is calculated by a virtual synchronous generator modulation voltage calculation formula , , ; S10, modulating the three-phase voltage output by the virtual synchronous generator , , SVPWM modulation is performed to generate switching signals for the inverter power devices.

2. The method of claim 1, wherein, the instantaneous power calculation formula being: 。 3. The method of claim 1, wherein the method further comprises: The two-phase filtered voltage The transformation of the two-phase stationary coordinate system to the two-phase rotating coordinate system obtains a d-axis filtered voltage and a q-axis filtered voltage The transformation formula is: 。 4. The method of claim 1, wherein, the single-synchronous frame phase-locked loop phase-locked formula being: wherein is a proportional regulator coefficient of the single-synchronous-frame phase-locked loop, is an integral regulator coefficient of the single-synchronous-frame phase-locked loop, is a Laplacian operator.

5. The method of claim 1, wherein, the active power loop calculation formula being: wherein is a virtual synchronous generator frequency droop coefficient, is a virtual synchronous generator virtual moment of inertia, is a Laplacian operator.

6. The method of fast power control of a virtual synchronous generator according to claim 1, characterized in that, the reactive power loop calculation formula being: wherein, is an inverter output reactive power reference value, is a virtual synchronous generator voltage droop coefficient, is a reactive power control inertia coefficient, is a Laplacian operator.

7. The method of fast power control of a virtual synchronous generator according to claim 1, characterized in that, the virtual synchronous generator modulation voltage calculation formula being: 。 8. A virtual synchronous generator fast power control system, characterized in that, comprising: Sampling module for acquiring a three-phase filtered voltage and a three-phase filtered current ​ A control module for performing a three-phase stationary coordinate system to two-phase stationary coordinate system transformation of a three-phase filtered voltage and a three-phase filtered current ​ For calculating the inverter output active power P and inverter output reactive power Q by the instantaneous power calculation formula and two-phase filter current , the calculation module a control module for extracting a filtered A-phase voltage phase angle of a control calculation of a previous round , and performing a two-phase stationary coordinate system to two-phase rotating coordinate system transformation on two-phase filtered voltages to obtain a d-axis filtered voltage and a q-axis filtered voltage ​ For calculating a q-axis filter voltage A calculation module for calculating a phase angle of an A-phase filter capacitor voltage through a single-synchronous-coordinate-system phase-locked-loop phase-locked formula ​ for calculating a reactive value of a three-phase power grid impedance , an inverter output active power original reference value , a three-phase power grid rated angular frequency and a three-phase power grid rated phase voltage amplitude , an inverter output active power actual reference value is calculated by a calculation module of a pre-filter calculation formula; A method for calculating a modulation wave angle of a virtual synchronous generator outputted by an inverter P and an actual reference value of an inverter output active power , by an active power loop calculation formula calculation module For calculating the modulation wave amplitude of the virtual synchronous generator output by the reactive power loop calculation formula , the d-axis filter voltage of the inverter output reactive power Q For modulating the amplitude of the output of a virtual synchronous generator and the angle of the modulating wave of the output of a virtual synchronous generator , the three-phase modulating voltage of the output of the virtual synchronous generator is calculated by a virtual synchronous generator modulating voltage calculation formula , , a calculation module Three-phase modulated voltage for virtual synchronous generator output , , a control module for performing SVPWM modulation to generate switching signals for the inverter power devices and a microprocessor and a memory, each of the modules, microprocessor being programmed or configured to perform the steps of the method of fast power control for a virtual synchronous generator of any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, the computer readable storage medium having stored therein a computer program that is programmed or configured to perform the method of fast power control for a virtual synchronous generator of any one of claims 1-7.

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