Network construction type converter and control method thereof based on adjustment of virtual admittance

Abstract

The invention provides a network construction type converter and a control method thereof based on virtual admittance adjustment. The method comprises the following steps: respectively extracting a voltage harmonic component and a current harmonic component from a grid-connected point voltage and a grid-side current of the converter; adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limiting value to obtain a first amplitude compensation amount and a first phase compensation amount; adjusting the deviation between the current harmonic component and the current harmonic amplitude limiting value to obtain a second amplitude compensation amount and a second phase compensation amount; according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, the amplitude set value and the phase set value, a virtual admittance parameter of the voltage regulator is updated, and the updated voltage regulator is obtained; and controlling the converter based on the updated voltage regulator. The method provided by the invention enhances the adaptability of the grid-forming converter to the power grid, and reduces the maintenance workload of products.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-type converter control, and in particular to a grid-type converter and a control method thereof based on adjusting virtual admittance. Background Art

[0002] Renewable energy generation is connected to the grid through converters. The support provided by renewable energy units to the grid is primarily achieved through converter control, which can be achieved through either the relatively mature grid-following control or the more recently emerging grid-forming control. Compared to grid-following control, grid-forming technology allows renewable energy units to operate similarly to synchronous machines. When the grid is disturbed, they can proactively respond to disturbances, just like synchronous machines in traditional power systems. This not only improves the renewable energy units' adaptability to the grid, but also further enhances their grid support capabilities.

[0003] However, existing research shows that while grid-based control offers a natural advantage in adapting to weak grids, renewable energy generators also face the challenge of poor adaptability to strong grids. In practical applications, converter control strategies and parameters often need to be adjusted based on grid strength to ensure optimal output performance in the desired grid environment.

[0004] Adjusting the control strategy and parameters will undoubtedly increase the difficulty of parameter design of the converter and increase the workload of its product maintenance. Summary of the Invention

[0005] The present invention provides a grid-type converter and a control method thereof based on adjusting virtual admittance, which enhances the adaptability of the grid-type converter to the power grid, improves the grid-connected robustness of the grid-type converter, and reduces the workload of product maintenance.

[0006] According to a first aspect of an embodiment of the present invention, a control method for a grid-type converter based on adjusting virtual admittance is provided, the method comprising:

[0007] Extracting voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter respectively;

[0008] Adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount;

[0009] Adjusting the deviation between the current harmonic component and the current harmonic amplitude limit value to obtain a second amplitude compensation amount and a second phase compensation amount;

[0010] updating a virtual admittance parameter of the voltage regulator according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, the amplitude setting value, and the phase setting value to obtain an updated voltage regulator;

[0011] The converter is controlled based on the updated voltage regulator.

[0012] In one possible implementation, extracting voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter respectively includes:

[0013] Collect the grid-connected point voltage and grid-side current of the converter;

[0014] Perform coordinate system transformation on the grid connection point voltage and grid-side current respectively to obtain the voltage vector and current vector in the αβ coordinate system;

[0015] A harmonic extractor is used to extract voltage harmonic components and current harmonic components from the voltage vector and current vector respectively.

[0016] In one possible implementation, adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount includes:

[0017] Determine the voltage harmonic component amplitude according to the voltage harmonic component;

[0018] The voltage harmonic deviation is calculated based on the voltage harmonic component amplitude and the voltage harmonic limit value;

[0019] A first virtual admittance amplitude regulator is used to adjust the voltage harmonic deviation to obtain a first amplitude compensation amount;

[0020] A first virtual admittance phase regulator is used to adjust the voltage harmonic deviation to obtain a first phase compensation amount.

[0021] In a possible implementation, the deviation between the current harmonic component and the current harmonic amplitude limit value is adjusted to obtain the second amplitude compensation amount and the second phase compensation amount Δθ VRV ,include:

[0022] According to the current harmonic components, the amplitude of the current harmonic components is determined;

[0023] The current harmonic deviation is calculated based on the current harmonic component amplitude and the current harmonic limit value;

[0024] A second virtual admittance amplitude regulator is used to adjust the current harmonic deviation to obtain a second amplitude compensation amount;

[0025] A second virtual admittance phase regulator is used to adjust the current harmonic deviation to obtain a second phase compensation amount.

[0026] In one possible implementation, updating a virtual admittance parameter of a voltage regulator according to a first amplitude compensation amount, a first phase compensation amount, a second amplitude compensation amount, a second phase compensation amount, an amplitude setting value, and a phase setting value to obtain an updated voltage regulator includes:

[0027] Determine the sum of the first amplitude compensation amount and the second amplitude compensation amount to obtain a target amplitude compensation amount;

[0028] Limiting the sum of the first phase compensation amount and the second phase compensation amount to obtain a target phase compensation amount;

[0029] According to the amplitude setting value, the phase setting value, the target amplitude compensation amount and the target phase compensation amount, the virtual admittance parameter of the voltage regulator is updated to obtain an updated voltage regulator.

[0030] In a possible implementation, the first phase compensation amount and the second phase compensation amount Δθ VRC The sum of the values ​​is limited to obtain the target phase compensation amount, including determining the target phase compensation amount using the following formula:

[0031]

[0032] Where Δθ VRV represents the first phase compensation amount, Δθ VRC represents the second phase compensation amount, Δθ VR Indicates the target phase compensation amount.

[0033] In one possible implementation, updating the virtual admittance parameter of the voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes determining the target virtual admittance parameter using the following formula:

[0034]

[0035] Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0 Indicates the initial phase setting value of the virtual admittance parameter;

[0036] The virtual admittance parameter of the voltage regulator is updated to the target virtual admittance parameter.

[0037] In one possible implementation, updating the virtual admittance parameter of the voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes determining the target virtual admittance parameter using the following formula:

[0038]

[0039] Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0 Indicates the initial phase setting value of the virtual admittance parameter;

[0040] Use the following formula to limit the target resistance setting value:

[0041]

[0042] Among them, L v Indicates the final inductance setting value, R v Indicates the final resistance setting value; L vmin and R vmin Respectively represent the lower limit of inductance and resistance;

[0043] The inductance value and the resistance value in the virtual admittance parameters are updated to the final inductance setting value and the final resistance setting value respectively.

[0044] In one possible implementation, controlling a converter based on an updated voltage regulator includes:

[0045] Determine active power and reactive power based on grid connection point voltage and grid-side current;

[0046] The deviation between the active power command value and the active power is adjusted by an active power regulator to obtain the output voltage phase;

[0047] The deviation between the reactive power command value and the reactive power is adjusted by a reactive power regulator to obtain an output voltage reference value;

[0048] The grid connection point voltage is transformed into a coordinate system according to the output voltage phase to obtain the voltage vector in the dq coordinate system;

[0049] Determine a voltage deviation between the voltage vector and an output voltage reference value in a dq coordinate system;

[0050] The voltage deviation is input into the updated voltage regulator to obtain the grid-side current command value;

[0051] The grid-side current is transformed into a coordinate system according to the output voltage phase to obtain the current vector in the dq coordinate system;

[0052] The deviation between the current vector and the grid-side current command value is adjusted using a current regulator, and then the voltage vector is superimposed to obtain the modulated voltage command value in the dq coordinate system.

[0053] According to the output voltage phase, the modulation voltage command value in the dq coordinate system is transformed to obtain the modulation voltage command value in the αβ coordinate system;

[0054] Based on the modulation voltage command value in the αβ coordinate system, PWM modulation is performed to generate a drive signal for controlling the converter.

[0055] According to a second aspect of an embodiment of the present invention, a grid-type converter is provided, comprising a controller configured to execute a control method for the grid-type converter based on adjusting virtual admittance in the first aspect or any possible implementation of the first aspect.

[0056] An embodiment of the present invention provides a grid-type converter and a control method thereof based on adjusting virtual admittance. The voltage regulator in the voltage regulation link adopts a virtual admittance adjustment method. Based on the voltage harmonic components and current harmonic components on the grid side of the converter, the virtual admittance parameters of the voltage regulator are dynamically updated. The updated voltage regulator is used to control the converter, so that the converter can adapt to changes in grid strength, enhance the adaptability of the grid-type converter to the grid, improve the grid-connected robustness of the grid-type converter, and reduce the workload of product maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0058] Figure 1 It is a schematic diagram of the structure of the existing grid-type converter control system;

[0059] Figure 2 A flow chart of a control method for a grid-type converter based on adjusting virtual admittance provided by an embodiment of the present invention;

[0060] Figure 3 This is a simulation waveform diagram when the control method based on adjusting virtual admittance of the grid-type converter provided by the embodiment of the present invention is not adopted;

[0061] Figure 4This is a simulation waveform diagram when the control method based on adjusting virtual admittance of the grid-type converter provided by an embodiment of the present invention is adopted;

[0062] Figure 5 A schematic diagram of a control structure for updating virtual admittance parameters provided by an embodiment of the present invention;

[0063] Figure 6 A schematic diagram of the control structure of a voltage and current control link provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0065] Converter: An electrical device that changes the voltage, frequency, number of phases, and other electrical quantities or characteristics of a power system. Renewable energy is connected to the grid through converters.

[0066] At present, the control system structure of the grid-type converter is as follows: Figure 1 As shown, where:

[0067] u oabc : The grid connection point voltage of the converter;

[0068] i oabc : grid-side current of the converter;

[0069] L pfc : filter inductance of the converter;

[0070] P ref , Q ref : Active power command value and reactive power command value output by the converter;

[0071] θ vsc : Output phase of the converter;

[0072] E ref : output voltage reference value of the converter;

[0073] e αβ_ref : Modulation voltage command value in αβ coordinate system;

[0074] u dc : DC bus voltage.

[0075] The grid side and the energy feeding side of the converter are connected through the DC bus. dcRepresents the DC bus voltage; the control system includes an active and reactive power control module, a voltage and current control module, and a pulse width modulation (PWM) modulation module. The active and reactive power control module, the voltage and current control module are connected, and the PWM modulation module is connected in sequence. The drive signal output by the PWM modulation module drives the converter.

[0076] Active and reactive power control module is based on converter P ref , Q ref 、u oabc and i oabc , generating E ref and θ vsc , voltage and current control module is based on u oabc 、i oabc 、E ref and θ vsc , generating e αβ_ref , PWM modulation module is based on e αβ_ref Modulation is performed, and the output drive signal drives the converter to generate waves.

[0077] Among them, the voltage and current control module includes a voltage regulation link and a current regulation link. The voltage control link adopts a voltage controller, which can adopt the control method of PI and virtual impedance, or the control method of virtual admittance regulator.

[0078] When the virtual admittance regulator is used for control, L represents the inductance in the virtual admittance parameter of the virtual admittance regulator, and R represents the resistance in the virtual admittance parameter of the virtual admittance regulator.

[0079] The embodiment of the present invention provides a control method for a grid-type converter based on adjusting virtual admittance, such as Figure 2 As shown, the method may include the following steps:

[0080] S210 , extracting voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter, respectively.

[0081] S220 , adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount.

[0082] S230 , adjusting the deviation between the current harmonic component and the current harmonic amplitude limit value to obtain a second amplitude compensation amount and a second phase compensation amount.

[0083] S240 , updating the virtual admittance parameters of the voltage regulator according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, the amplitude setting value, and the phase setting value to obtain an updated voltage regulator.

[0084] S250 controls the converter based on the updated voltage regulator.

[0085] like Figure 4 、 Figure 5 As shown, at the 5th second, the grid strength changes. Without the control method provided by the embodiment of the present invention, the grid-connection point voltage and output current (i.e., grid-side current) of the converter continue to oscillate. However, with the control method provided by the embodiment of the present invention, the grid-connection point voltage and output current (i.e., grid-side current) of the converter return to normal after a brief fluctuation. This shows that the control method provided by the embodiment of the present invention enables the converter to adapt to changes in grid strength.

[0086] An embodiment of the present invention provides a control method for a grid-type converter based on adjusting virtual admittance. The voltage regulator in the voltage regulation link adopts a virtual admittance adjustment method. Based on the voltage harmonic components and current harmonic components on the grid side of the converter, the virtual admittance parameters of the voltage regulator are dynamically updated. The updated voltage regulator is used for control, so that the converter can adapt to changes in grid strength, enhance the adaptability of the grid-type converter to the grid, improve the grid-connected robustness of the grid-type converter, and reduce the workload of product maintenance.

[0087] In one embodiment, S210: extracting voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter respectively may include the following steps:

[0088] S211, collecting the grid-connected point voltage and grid-side current of the converter.

[0089] S212 , performing coordinate system conversion on the grid connection point voltage and the grid-side current respectively to obtain the voltage vector and the current vector in the αβ coordinate system.

[0090] like Figure 5 As shown, the grid voltage u oabc , grid-side current i oabc Convert to the αβ coordinate system according to equations (1) and (2) respectively.

[0091] u oαβ =T 3s / 2s u oabc (1)

[0092] i oαβ =T 3s / 2s i oabc (2)

[0093] Where u oαβ is the voltage vector in the αβ coordinate system corresponding to the grid connection point voltage, i oαβ is the current vector in the αβ coordinate system corresponding to the grid-side current, T 3s / 2s is the coordinate transformation matrix, and its expression is

[0094]

[0095] S213 , using a harmonic extractor, extracting voltage harmonic components and current harmonic components from the voltage vector and the current vector respectively.

[0096] The harmonic extractor is used to extract harmonic components other than the fundamental wave in voltage and current, and can be a fundamental wave trap.

[0097] By using the harmonic extractor HPF to extract the voltage vector u oαβ The voltage harmonic component u in oαβh , current vector i oαβ The current harmonic component i oαβh .

[0098] The method provided in the embodiment of the present invention extracts the voltage harmonic components in the grid-connected point voltage and the current harmonic components in the grid-side current. The voltage harmonic components and the current harmonic components can reflect the changes in the strength of the power grid.

[0099] In one embodiment, S220: adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount may include the following steps:

[0100] S221, determining the voltage harmonic component amplitude according to the voltage harmonic component.

[0101] like Figure 5 As shown, according to the voltage harmonic component u oαβh Determine the voltage harmonic component amplitude U omh .

[0102] S222: Calculate the voltage harmonic deviation based on the voltage harmonic component amplitude and the voltage harmonic amplitude limit value.

[0103]

[0104] Among them, U LmtErr Indicates voltage harmonic deviation, U omh Indicates the amplitude of voltage harmonic components, U hLmt Indicates voltage harmonic limiting.

[0105] S223: Use a first virtual admittance amplitude regulator to adjust the voltage harmonic deviation to obtain a first amplitude compensation amount.

[0106] The first virtual admittance amplitude regulator is used to adjust the voltage harmonic deviation U LmtErr , get the first amplitude compensation ΔZ VRVm .

[0107] G VVR is the transfer function of the first virtual admittance amplitude regulator, which can adopt proportional integral control, integral control or proportional control.

[0108] S224: Use a first virtual admittance phase regulator to adjust the voltage harmonic deviation to obtain a first phase compensation amount.

[0109] The first virtual admittance phase regulator is used to adjust the voltage harmonic deviation U LmtErr , and obtain the first phase compensation value Δθ VRV .

[0110] Among them, G Vθ is the transfer function of the voltage virtual admittance phase regulator, which can adopt proportional integral control, integral control or proportional control.

[0111] The method provided by the embodiment of the present invention generates a first amplitude compensation amount and a first phase compensation amount for updating a virtual admittance parameter based on a voltage harmonic component.

[0112] In one embodiment, S230: adjusting the deviation between the current harmonic component and the current harmonic amplitude limit value to obtain a second amplitude compensation amount and a second phase compensation amount may include the following steps:

[0113] S231, determining the amplitude of the current harmonic component according to the current harmonic component.

[0114] like Figure 5 As shown, according to the current harmonic component i oαβh , determine the amplitude of the current harmonic component I omh .

[0115] S232: Calculate the current harmonic deviation based on the current harmonic component amplitude and the current harmonic amplitude limit value.

[0116]

[0117] Among them, I LmtErr Indicates the current harmonic deviation, I omh Indicates the amplitude of the current harmonic component, I hLmt Indicates current harmonic limiting.

[0118] S233: Use a second virtual admittance amplitude regulator to adjust the current harmonic deviation to obtain a second amplitude compensation amount.

[0119] The second virtual admittance amplitude regulator is used to adjust the current harmonic deviation to obtain the second amplitude compensation ΔZ VRCm .

[0120] G CVR is the transfer function of the second virtual admittance amplitude regulator, which can adopt proportional integral control, integral control or proportional control.

[0121] S234: Use a second virtual admittance phase regulator to adjust the current harmonic deviation to obtain a second phase compensation amount.

[0122] The second virtual admittance phase regulator is used to adjust the current harmonic deviation I LmtErr , and obtain the second phase compensation value Δθ VRC .

[0123] Among them, G Cθ is the transfer function of the second virtual admittance phase regulator, which can adopt proportional integral control, integral control or proportional control.

[0124] The method provided by the embodiment of the present invention generates a second amplitude compensation amount and a second phase compensation amount for updating virtual admittance parameters based on voltage harmonic components.

[0125] In one embodiment, S240: updating the virtual admittance parameter of the voltage regulator according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, the amplitude setting value, and the phase setting value to obtain an updated voltage regulator may include the following steps:

[0126] S241 , determining the sum of the first amplitude compensation amount and the second amplitude compensation amount to obtain a target amplitude compensation amount.

[0127] like Figure 5 As shown, the first amplitude compensation amount ΔZ is calculated VRVm and the second amplitude compensation amount ΔZ VRCm The sum of the target amplitude compensation ΔZ is obtained. VRm .

[0128] S242 , limiting the sum of the first phase compensation amount and the second phase compensation amount to obtain a target phase compensation amount.

[0129] In one example, the first phase compensation amount Δθ VRV and the second phase compensation amount Δθ VRC The sum of the values ​​is limited to obtain the target phase compensation Δθ VR , including determining the target phase compensation amount Δθ using the following formula VR :

[0130]

[0131] Where Δθ VRV represents the first phase compensation amount, Δθ VRC represents the second phase compensation amount, Δθ VR Indicates the target phase compensation amount.

[0132] S243 , updating the virtual admittance parameters of the voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount to obtain an updated voltage regulator.

[0133] In one example, updating the virtual admittance parameter of the voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes: first, determining the target virtual admittance parameter using the following formula:

[0134]

[0135] Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0 Indicates the initial phase setting value of the virtual admittance parameter.

[0136] Then, the virtual admittance parameter of the voltage regulator is updated to the target virtual admittance parameter.

[0137] like Figure 6 As shown, in the voltage control link, the virtual admittance parameter of the voltage regulator includes the inductance value and the resistance value. The inductance value in the virtual admittance parameter is updated to L VR , update the resistance value in the virtual admittance parameter to R VR .

[0138] In another example, updating the virtual admittance parameter of the voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes: first, determining the target virtual admittance parameter using the following formula:

[0139]

[0140] Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0Indicates the initial phase setting value of the virtual admittance parameter.

[0141] Then, the target resistance setting value is limited using the following formula:

[0142]

[0143] Among them, L v Indicates the final inductance setting value, R v Indicates the final resistance setting value; L vmin and R vmin They represent the lower limit of inductance and resistance respectively.

[0144] Finally, the inductance value and resistance value in the virtual admittance parameters are updated to the final inductance setting value and the final resistance setting value respectively.

[0145] The virtual admittance parameter of the voltage regulator includes the inductance value and the resistance value. The inductance value in the virtual admittance parameter is updated to L v , update the resistance value in the virtual admittance parameter to R v .

[0146] The method provided by the embodiment of the present invention updates the virtual admittance parameter of the voltage regulator, so that the converter can adapt to the change of the power grid strength.

[0147] In one embodiment, S250: controlling the converter based on the updated voltage regulator may include the following steps:

[0148] S251, determining active power and reactive power according to the grid connection point voltage and grid-side current.

[0149] According to the grid voltage u oabc and grid-side current i oabc Perform power calculation to obtain active power P vsc and reactive power Q vsc .

[0150] S252: The active power regulator is used to adjust the deviation between the active power command value and the active power to obtain an output voltage phase.

[0151] It can be expressed as follows:

[0152]

[0153] Among them, θ vsc Indicates the output voltage phase; G PR represents the transfer function of the active power regulator, J and D are virtual moment of inertia and damping coefficient respectively; P ref Indicates the active power command value; P vsc Represents active power; ωfw Indicates the frequency feedforward amount.

[0154] S253, adjusting the deviation between the reactive power command value and the reactive power using a reactive power regulator to obtain an output voltage reference value.

[0155] It can be expressed as follows:

[0156] E ref =G QR (Q ref -Q vsc )+U fw (10)

[0157] S254 , performing coordinate transformation on the grid connection point voltage according to the output voltage phase to obtain a voltage vector in a dq coordinate system.

[0158] like Figure 6 As shown, it can be expressed by the following formula:

[0159] u dq_ref =E ref +j0(11)

[0160] u odq =T 3s / 2r u oabc (12)

[0161]

[0162] Among them, u dq_ref Indicates the output voltage reference value in the dq coordinate system, u odq It represents the voltage vector of the grid connection point voltage in the dq coordinate system.

[0163] S255 , determining a voltage deviation between the voltage vector and the output voltage reference value in the dq coordinate system.

[0164] S256: Input the voltage deviation into the updated voltage regulator to obtain a grid-side current command value.

[0165] like Figure 6 As shown, it can be expressed by the following formula:

[0166]

[0167] Among them, i dq_ref Indicates the grid-side current command value.

[0168] S257 , performing coordinate transformation on the grid-side current according to the output voltage phase to obtain a current vector in a dq coordinate system.

[0169] like Figure 6 As shown, it can be expressed by the following formula:

[0170] i dq =T 3s / 2r i oabc (15)

[0171] Among them, i dq Represents the current vector of the grid-side current in the dq coordinate system.

[0172] S258 , after adjusting the deviation between the current vector and the grid-side current command value using a current regulator, the voltage vector is superimposed to obtain a modulation voltage command value in a dq coordinate system.

[0173] like Figure 6 As shown, it can be expressed by the following formula:

[0174] e dq_ref =G CR (i dq_ref -i dq )+u odq (16)

[0175] Among them, e dq_ref Indicates the modulation voltage command value in the dq coordinate system, G CR represents the transfer function of the current regulator.

[0176] S259 , performing coordinate transformation on the modulation voltage command value in the dq coordinate system according to the output voltage phase, to obtain the modulation voltage command value in the αβ coordinate system.

[0177] like Figure 6 As shown, it can be expressed by the following formula:

[0178]

[0179] Among them, e dq_ref Indicates the modulation voltage command value in the αβ coordinate system.

[0180] S2510: Perform PWM modulation based on the modulation voltage command value in the αβ coordinate system to generate a drive signal for controlling the converter.

[0181] The embodiments of the present invention provide a grid-type converter and a control method based on adjusting virtual admittance. The voltage regulator in the voltage regulation link adopts a virtual admittance adjustment method, and dynamically updates the virtual admittance parameters of the voltage regulator based on the voltage harmonic components and current harmonic components on the grid side of the converter. The updated voltage regulator is used to control the converter, so that the converter can adapt to changes in grid strength, enhance the adaptability of the grid-type converter to the grid, improve the grid-connected robustness of the grid-type converter, and reduce the workload of product maintenance.

[0182] An embodiment of the present invention further provides a meshed converter, comprising a controller configured to execute the meshed converter control method based on virtual admittance adjustment described in the above-described embodiment. This meshed converter includes functional modules and benefits corresponding to executing the meshed converter control method based on virtual admittance adjustment. Technical details not fully described in this embodiment can be found in the specific processing details of the meshed converter control method based on virtual admittance adjustment provided in the above-described embodiment of the present invention and will not be further elaborated here.

[0183] For simplicity of description, the aforementioned method embodiments are described as a series of actions. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions and modules involved are not necessarily required for the present invention.

[0184] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similarities between the various embodiments can be referred to in conjunction with each other. For device embodiments, since they are generally similar to method embodiments, their description is relatively simple, and for relevant details, reference can be made to the description of the method embodiments.

[0185] The steps in the methods of the various embodiments of the present invention can be adjusted in sequence, combined, and deleted according to actual needs, and the technical features recorded in the various embodiments can be replaced or combined.

[0186] The modules and submodules in the devices and terminals of various embodiments of the present invention may be combined, divided, or deleted according to actual needs.

[0187] In the several embodiments provided herein, it should be understood that the disclosed terminals, devices, and methods can be implemented in other ways. For example, the terminal embodiments described above are merely illustrative. For example, the division of modules or submodules is merely a logical functional division. In actual implementation, other division methods may be used, such as combining or integrating multiple submodules or modules into another module, or omitting or not implementing certain features. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or modules via some interface, which may be electrical, mechanical, or other forms.

[0188] The modules or submodules described as separate components may or may not be physically separate, and the components of the modules or submodules may or may not be physical modules or submodules, that is, they may be located in one place or distributed across multiple network modules or submodules. Some or all of the modules or submodules may be selected to achieve the purpose of this embodiment according to actual needs.

[0189] In addition, the functional modules or submodules in the various embodiments of the present invention may be integrated into a single processing module, or each module or submodule may exist physically separately, or two or more modules or submodules may be integrated into a single module. The aforementioned integrated modules or submodules may be implemented in the form of hardware or software functional modules or submodules.

[0190] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0191] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, software units executed by a processor, or a combination of the two. The software units may be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0192] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0193] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a grid-type converter based on adjusting virtual admittance, characterized in that: The method comprises: Extracting voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter respectively; Adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount; Adjusting the deviation between the current harmonic component and the current harmonic amplitude limit value to obtain a second amplitude compensation amount and a second phase compensation amount; updating a virtual admittance parameter of a voltage regulator according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, an amplitude setting value, and a phase setting value to obtain an updated voltage regulator; The converter is controlled based on the updated voltage regulator.

2. The method according to claim 1, characterized in that Extract voltage harmonic components and current harmonic components from the grid-connected point voltage and grid-side current of the converter, including: collecting the grid-connected point voltage and grid-side current of the converter; Performing coordinate system conversion on the grid-connected point voltage and the grid-side current respectively to obtain a voltage vector and a current vector in an αβ coordinate system; A harmonic extractor is used to extract voltage harmonic components and current harmonic components from the voltage vector and current vector respectively.

3. The method according to claim 1, characterized in that Adjusting the deviation between the voltage harmonic component and the voltage harmonic amplitude limit value to obtain a first amplitude compensation amount and a first phase compensation amount includes: Determine the voltage harmonic component amplitude according to the voltage harmonic component; Calculating the voltage harmonic deviation based on the voltage harmonic component amplitude and the voltage harmonic limit value; Using a first virtual admittance amplitude regulator to adjust the voltage harmonic deviation to obtain the first amplitude compensation amount; The voltage harmonic deviation is adjusted using a first virtual admittance phase regulator to obtain the first phase compensation amount.

4. The method according to claim 1, wherein Adjusting the deviation between the current harmonic component and the current harmonic amplitude limit value to obtain a second amplitude compensation amount and a second phase compensation amount includes: According to the current harmonic components, the amplitude of the current harmonic components is determined; Calculating the current harmonic deviation based on the current harmonic component amplitude and the current harmonic limit value; Using a second virtual admittance amplitude regulator to adjust the current harmonic deviation to obtain the second amplitude compensation amount; A second virtual admittance phase regulator is used to adjust the current harmonic deviation to obtain the second phase compensation amount.

5. The method according to claim 1, wherein Updating a virtual admittance parameter of a voltage regulator according to the first amplitude compensation amount, the first phase compensation amount, the second amplitude compensation amount, the second phase compensation amount, an amplitude setting value, and a phase setting value to obtain an updated voltage regulator, comprising: determining a sum of the first amplitude compensation amount and the second amplitude compensation amount to obtain a target amplitude compensation amount; limiting a sum of the first phase compensation amount and the second phase compensation amount to obtain a target phase compensation amount; The virtual admittance parameter of the voltage regulator is updated according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount to obtain an updated voltage regulator.

6. The method according to claim 5, characterized in that Limiting the sum of the first phase compensation amount and the second phase compensation amount to obtain a target phase compensation amount includes determining the target phase compensation amount using the following formula: Where Δθ VRV represents the first phase compensation amount, Δθ VRC represents the second phase compensation amount, Δθ VR represents the target phase compensation amount.

7. The method according to claim 5, characterized in that Updating a virtual admittance parameter of a voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes: determining a target virtual admittance parameter using the following formula: Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0 Indicates the initial phase setting value of the virtual admittance parameter; The virtual admittance parameter of the voltage regulator is updated to the target virtual admittance parameter.

8. The method according to claim 5, characterized in that Updating a virtual admittance parameter of a voltage regulator according to the amplitude setting value, the phase setting value, the target amplitude compensation amount, and the target phase compensation amount includes: determining a target virtual admittance parameter using the following formula: Among them, ω g Indicates the grid angular frequency, L VR Indicates the target inductance setting value in the target virtual admittance parameter; R VR Indicates the target resistance setting value in the target virtual admittance parameter, Z VR0m Represents the initial amplitude setting value of the virtual admittance parameter; θ VR0 Indicates the initial phase setting value of the virtual admittance parameter; The target resistance setting value is limited using the following formula: Among them, L v Indicates the final inductance setting value, R v Indicates the final resistance setting value; L vmin and R vmin Respectively represent the lower limit of inductance and resistance; The inductance value and the resistance value in the virtual admittance parameters are updated to the final inductance setting value and the final resistance setting value respectively.

9. The method according to claim 1, characterized in that Controlling the converter based on the updated voltage regulator includes: Determine active power and reactive power based on grid connection point voltage and grid-side current; The active power regulator is used to adjust the deviation between the active power command value and the active power to obtain the output voltage phase; The reactive power command value and the reactive power deviation are adjusted by a reactive power regulator to obtain an output voltage reference value; Performing coordinate transformation on the grid connection point voltage according to the output voltage phase to obtain a voltage vector in a dq coordinate system; Determining a voltage deviation between the voltage vector and an output voltage reference value in a dq coordinate system; Inputting the voltage deviation into the updated voltage regulator to obtain a grid-side current command value; Performing coordinate transformation on the grid-side current according to the output voltage phase to obtain a current vector in a dq coordinate system; The deviation between the current vector and the grid-side current command value is adjusted by a current regulator, and then the voltage vector is superimposed to obtain a modulation voltage command value in a dq coordinate system; According to the output voltage phase, the modulation voltage command value in the dq coordinate system is transformed to obtain the modulation voltage command value in the αβ coordinate system; Based on the modulation voltage command value in the αβ coordinate system, PWM modulation is performed to generate a drive signal for controlling the converter.

10. A grid-type converter, characterized in that: The grid-type converter includes a controller, and the controller is used to execute the control method of the grid-type converter based on adjusting virtual admittance according to any one of claims 1 to 9.

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