Method and device for controlling network-forming type grid-connected converter

Abstract

The invention provides a control method and device for a network-forming type grid-connected converter. According to the output voltage stable value of the grid-connected converter under the two-phase rotating coordinate system and the current reference value of the filter inductor under the two-phase static coordinate system, the voltage and current inner loop control of the grid-connected converter is realized, the control performance of the grid-connected converter can be improved, and the stable operation of the grid-connected converter is ensured. According to the invention, the actual value of the output voltage of the grid-connected converter under the two-phase static coordinate system is calculated according to the actual value of the current of the filter inductor and the actual value of the voltage of the primary winding, so that the state feedback control of the grid-connected converter is realized, and the dynamic characteristics of the grid-connected converter can be improved. And the control dimension of the network construction type grid-connected converter can be effectively increased.

Description

A control method and apparatus for a grid-connected converter Technical Field

[0001] This application relates to the field of power electronics technology, specifically to a control method and device for a grid-connected converter. Background Technology

[0002] Grid-connected converters, as a key component connecting distributed generation to the AC power grid, play a vital role in converting direct current (DC) into high-quality alternating current (AC) and transmitting it to the grid. Therefore, the stable, safe, and economical operation of grid-connected converters is of great significance to the power system.

[0003] Grid-connected converters are mainly divided into two control methods: grid-following (GFL) grid-connected converters (which can be simply referred to as GFL converters) and grid-forming (GFM) grid-connected converters (which can be simply referred to as GFM converters). With the increasing penetration rate of new energy sources based on power electronic devices, the high-inertia, strong power grid dominated by generators is gradually shifting to a low-inertia, weak power grid dominated by power electronic devices. Grid-following grid-connected converters lack stability under weak power grid conditions and cannot provide system support. In contrast, grid-forming grid-connected converters, benefiting from the simulation of synchronous generator characteristics, can actively provide frequency and voltage support, exhibiting better stability under weak power grid conditions. Therefore, grid-forming grid-connected converters are gradually gaining widespread application.

[0004] In existing technologies, voltage and current dual closed-loop control is used to control grid-connected converters. However, because current and voltage are cascaded based on a single input and single output, the stability and control performance of grid-connected converters are poor. Summary of the Invention

[0005] To address the issues of poor stability and control performance of grid-connected converters in the prior art, this application provides a control method and apparatus for grid-connected converters.

[0006] In one aspect, this application provides a control method for a grid-connected converter, which is connected to a transformer via a filter. The control method includes: determining the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding and the reference voltage value of the primary winding in the transformer.

[0007] The reference value of the current of the filter inductor in the filter is determined based on the actual value of the three-phase current in the primary winding of the transformer and the reference value of the voltage in the primary winding.

[0008] The grid-connected converter is controlled based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system.

[0009] In some possible implementations, the output voltage stability value of the grid-connected converter in a two-phase rotating coordinate system is determined based on the actual value of the three-phase current in the primary winding of the transformer and the reference value of the voltage in the primary winding. This includes: performing Park transformation on the actual value of the three-phase current in the primary winding to obtain the actual value of the d-axis current and the actual value of the q-axis current in the two-phase rotating coordinate system.

[0010] The stable values ​​of the d-axis output voltage and q-axis output voltage of the grid-connected converter in the two-phase rotating coordinate system are calculated based on the actual values ​​of the d-axis current, q-axis current, d-axis voltage reference value, and q-axis voltage reference value of the primary winding in the two-phase rotating coordinate system.

[0011] Optionally, the stable value of the d-axis output voltage of the grid-connected converter in a two-phase rotating coordinate system satisfies: .

[0012] in, This represents the stable d-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This indicates the capacitance value of the filter capacitor in the filter.

[0013] The q-axis output voltage stability value of a grid-connected converter in a two-phase rotating coordinate system satisfies:

[0014] in, This represents the stable q-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

[0015] In some other possible implementations, the reference value of the filter inductor in the filter in a two-phase stationary coordinate system is determined based on the actual value of the three-phase current in the primary winding of the transformer and the reference value of the voltage in the primary winding. This includes performing a Parker transformation on the actual value of the three-phase current in the primary winding to obtain the actual value of the d-axis current and the actual value of the q-axis current in the two-phase rotating coordinate system.

[0016] The reference value of the d-axis current of the filter inductor in the two-phase rotating coordinate system is calculated based on the actual value of the d-axis current and the reference value of the q-axis voltage of the primary winding in the two-phase rotating coordinate system.

[0017] By performing an inverse Parker transformation on the d-axis and q-axis current reference values ​​of the filter inductor in a two-phase rotating coordinate system, the current reference value of the filter inductor in a two-phase stationary coordinate system is obtained.

[0018] Optionally, the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This indicates the capacitance value of the filter capacitor in the filter.

[0019] The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, Reference value of q-axis current of filter inductor in two-phase rotating coordinate system This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the reference value of the d-axis voltage of the primary winding in a two-phase rotating coordinate system.

[0020] In some other possible implementations, the grid-connected converter is controlled based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the current reference value of the filter inductor in the two-phase stationary coordinate system. This includes: performing an inverse Park transform on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system to obtain the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system.

[0021] The actual output voltage of the grid-connected converter in the two-phase stationary coordinate system is calculated based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system.

[0022] The actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system is modulated to obtain the control signal.

[0023] The grid-connected converter is controlled according to the control signal.

[0024] Furthermore, based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system, the actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system is calculated, including: performing a Clark transformation on the actual voltage value of the primary winding to obtain the actual α-axis voltage value and the actual β-axis voltage value of the primary winding in the two-phase stationary coordinate system.

[0025] By performing a Clarke transform on the actual current value of the filter inductor, the actual α-axis current value and β-axis current value of the filter inductor in the two-phase stationary coordinate system are obtained.

[0026] The actual values ​​of the α-axis and β-axis output voltages of the grid-connected converter in the two-phase stationary coordinate system are calculated based on the stable values ​​of the α-axis and β-axis output voltages of the primary winding in the two-phase stationary coordinate system, the actual values ​​of the α-axis and β-axis voltages of the primary winding in the two-phase stationary coordinate system, the actual values ​​of the α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system, and the reference values ​​of the α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system.

[0027] Optionally, the actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual α-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable output voltage value along the α-axis of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second-state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

[0028] Secondly, this application provides a control device for a grid-connected converter. The grid-connected converter is connected to a transformer via a filter. The control device includes: a first determining module, used to determine the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding and the reference voltage value of the primary winding in the transformer.

[0029] The second determining module is used to determine the reference value of the current of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual value of the three-phase current of the primary winding in the transformer and the reference value of the voltage of the primary winding.

[0030] The control module is used to control the grid-connected converter based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the current reference value of the filter inductor in the two-phase stationary coordinate system.

[0031] In some possible implementations, the first determining module is specifically used to: perform Park transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current values ​​and q-axis current values ​​of the primary winding in a two-phase rotating coordinate system.

[0032] The stable values ​​of the d-axis output voltage and q-axis output voltage of the grid-connected converter in the two-phase rotating coordinate system are calculated based on the actual values ​​of the d-axis current, q-axis current, d-axis voltage reference value, and q-axis voltage reference value of the primary winding in the two-phase rotating coordinate system.

[0033] Optionally, the stable value of the d-axis output voltage of the grid-connected converter in a two-phase rotating coordinate system satisfies: .

[0034] in, This represents the stable d-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This indicates the capacitance value of the filter capacitor in the filter.

[0035] The q-axis output voltage stability value of a grid-connected converter in a two-phase rotating coordinate system satisfies:

[0036] in, This represents the stable q-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

[0037] In some other possible implementations, the second determining module is specifically used to: perform Park transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current values ​​and q-axis current values ​​of the primary winding in a two-phase rotating coordinate system.

[0038] The reference value of the d-axis current of the filter inductor in the two-phase rotating coordinate system is calculated based on the actual value of the d-axis current and the reference value of the q-axis voltage of the primary winding in the two-phase rotating coordinate system.

[0039] By performing an inverse Parker transformation on the d-axis and q-axis current reference values ​​of the filter inductor in a two-phase rotating coordinate system, the current reference value of the filter inductor in a two-phase stationary coordinate system is obtained.

[0040] Optionally, the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This indicates the capacitance value of the filter capacitor in the filter.

[0041] The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, Reference value of q-axis current of filter inductor in two-phase rotating coordinate system This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the reference value of the d-axis voltage of the primary winding in a two-phase rotating coordinate system.

[0042] In some other possible implementations, the control module is specifically used to: perform an inverse Park transform on the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system to obtain the stable output voltage value of the grid-connected converter in a two-phase stationary coordinate system.

[0043] The actual output voltage of the grid-connected converter in the two-phase stationary coordinate system is calculated based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system.

[0044] The actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system is modulated to obtain the control signal.

[0045] The grid-connected converter is controlled according to the control signal.

[0046] Furthermore, the control module is specifically used to: perform Clarke transformation on the actual voltage value of the primary winding to obtain the actual voltage values ​​of the primary winding along the α-axis and β-axis in the two-phase stationary coordinate system.

[0047] By performing a Clarke transform on the actual current value of the filter inductor, the actual α-axis current value and β-axis current value of the filter inductor in the two-phase stationary coordinate system are obtained.

[0048] The actual values ​​of the α-axis and β-axis output voltages of the grid-connected converter in the two-phase stationary coordinate system are calculated based on the stable values ​​of the α-axis and β-axis output voltages of the primary winding in the two-phase stationary coordinate system, the actual values ​​of the α-axis and β-axis voltages of the primary winding in the two-phase stationary coordinate system, the actual values ​​of the α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system, and the reference values ​​of the α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system.

[0049] Optionally, the actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual α-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable output voltage value along the α-axis of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second-state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

[0050] In another aspect, this application also provides a computer device, including: one or more processors.

[0051] A processor is used to execute one or more programs.

[0052] When one or more programs are executed by one or more processors, the control method described above is implemented.

[0053] Furthermore, this application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, it implements the control method described above.

[0054] Compared with the prior art, the beneficial effects of this application are as follows: In the control method of the grid-connected converter provided in this application, the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system is determined based on the actual three-phase current value and the voltage reference value of the primary winding in the transformer. The current reference value of the filter inductor in the filter in the two-phase stationary coordinate system is determined based on the actual three-phase current value and the voltage reference value of the primary winding in the transformer. Then, based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the current reference value of the filter inductor in the two-phase stationary coordinate system, the voltage and current inner loop control of the grid-connected converter is realized, which can improve the control performance of the grid-connected converter and ensure its stable operation.

[0055] This application calculates the actual output voltage of the grid-connected converter in a two-phase stationary coordinate system based on the actual current value of the filter inductor and the actual voltage value of the primary winding, thereby realizing the state feedback control of the grid-connected converter. This can improve the dynamic characteristics of the grid-connected converter and effectively increase the control dimensions of the grid-connected converter.

[0056] In calculating the actual output voltage of a grid-connected converter in a two-phase stationary coordinate system, this application considers a first state feedback coefficient and a second state feedback coefficient. The first state feedback coefficient and the second state feedback coefficient can be set and adjusted according to specific application scenarios, which simplifies the difficulty of the control process and makes the control method universal. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 is a schematic diagram of a grid-connected converter connected to an AC power grid in an embodiment of this application; Figure 2 is a schematic flowchart of a control method for a grid-connected converter in an embodiment of this application; Figure 3 is a schematic flowchart of outputting a control signal based on the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system and the current reference value of the filter inductor in a two-phase stationary coordinate system in an embodiment of this application; Figure 4 is a schematic flowchart of determining the current reference value of the filter inductor in a two-phase stationary coordinate system in an embodiment of this application; Figure 5a is a schematic flowchart of an embodiment of this application. Figure 5a is a diagram of the overall voltage waveform of the primary winding in this embodiment; Figure 5b is a diagram of the partial voltage waveform of the primary winding in this embodiment; Figure 5c is a diagram of the overall current waveform of the primary winding in this embodiment; Figure 5d is a diagram of the partial current waveform of the primary winding in this embodiment; Figure 6a is a diagram of the voltage waveform obtained by performing a Fourier transform on the voltage of the primary winding in this embodiment; Figure 6b is a diagram of the current waveform obtained by performing a Fourier transform on the current of the primary winding in this embodiment; Figure 7 is a schematic structural diagram of the control device of the grid-connected converter in this embodiment. Detailed Implementation

[0059] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0060] The terms "first," "second," etc., used in the specification, embodiments, claims, and drawings of this application are for distinguishing purposes only and should not be construed as indicating or implying relative importance or order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or apparatus is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0061] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0062] Example 1: This application provides a control method for a grid-connected converter. As shown in Figure 1, the grid-connected converter 10 can be connected to a transformer 30 via a filter 20. The filter 20 may include a filter capacitor C and a filter inductor L. The transformer may include a primary winding 31 and a secondary winding 32. The primary winding 31 is connected to the filter, and the secondary winding 32 is connected to the AC power grid G. dc This represents the DC-side voltage of the grid-connected converter 10, u. vsca u vscb u vscc i represents the actual output voltage value of the grid-connected converter 10. La i Lb i Lc u represents the actual value of the current in the filter inductor. Ca u Cb u Cc i represents the actual voltage value of the primary winding. Ca i Cb i Cc i represents the actual current value of the filter capacitor. 2a i 2b i 2c u represents the actual value of the current in the primary winding. 2au 2b u 2c i represents the actual voltage value of the secondary winding. ga i gb i gc This represents the actual value of the current in the AC power grid. In this embodiment, only the inductance L of the AC power grid is considered. g u ga u gb u gc This indicates the actual voltage value of the AC power grid.

[0063] As shown in Figure 2, the control method 100 may include the following steps: Step S1: Determine the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system based on the actual value of the three-phase current of the primary winding in the transformer and the reference value of the voltage of the primary winding.

[0064] Step S2: Determine the reference value of the current of the filter inductor in the filter in the two-phase stationary coordinate system based on the actual value of the three-phase current of the primary winding in the transformer and the reference value of the voltage of the primary winding.

[0065] Step S3: Control the grid-connected converter based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system.

[0066] In some possible implementations, step S1, which determines the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value and the reference voltage value of the primary winding in the transformer, includes: performing a Parker transformation on the actual three-phase current value of the primary winding to obtain the actual d-axis current value of the primary winding in a two-phase rotating coordinate system. and actual value of q-axis current .

[0067] Referring to Figure 3, based on the actual d-axis current value of the primary winding in a two-phase rotating coordinate system... Actual value of q-axis current d-axis voltage reference value and q-axis voltage reference value Calculate the d-axis output voltage stability of a grid-connected converter in a two-phase rotating coordinate system. and q-axis output voltage stability .

[0068] Optionally, the stable value of the d-axis output voltage of the grid-connected converter in a two-phase rotating coordinate system satisfies:

[0069] in, This represents the stable d-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This indicates the capacitance value of the filter capacitor in the filter.

[0070] The q-axis output voltage stability value of a grid-connected converter in a two-phase rotating coordinate system satisfies:

[0071] in, This represents the stable q-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

[0072] In some other possible implementations, step S2, which determines the current reference value of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual three-phase current value and the voltage reference value of the primary winding in the transformer, includes: performing a Parker transformation on the actual three-phase current value of the primary winding to obtain the actual d-axis current value of the primary winding in a two-phase rotating coordinate system. and actual value of q-axis current .

[0073] Referring to Figure 4, based on the actual d-axis current value of the primary winding in a two-phase rotating coordinate system... and q-axis voltage reference value Calculate the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. Based on the actual value of the q-axis current of the primary winding in a two-phase rotating coordinate system and d-axis voltage reference value Calculate the reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system. .

[0074] The d-axis current reference value of the filter inductor in a two-phase rotating coordinate system can be determined based on the phase angle θ of the AC power grid. and q-axis current reference value Performing an inverse Park transform (i.e., abc / αβ transform, inverse Park transform) yields the current reference value of the filter inductor in the two-phase stationary coordinate system (including the α-axis current reference value of the filter inductor in the two-phase stationary coordinate system). and β-axis current reference value ).

[0075] Optionally, the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This indicates the capacitance value of the filter capacitor in the filter.

[0076] The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, Reference value of q-axis current of filter inductor in two-phase rotating coordinate system This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the reference value of the d-axis voltage of the primary winding in a two-phase rotating coordinate system.

[0077] In some other possible implementations, step S3 involves controlling the grid-connected converter based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system. This includes: referring to Figure 3, controlling the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system (including the stable output voltage value of the grid-connected converter along the d-axis in the two-phase rotating coordinate system). and q-axis output voltage stability Perform an inverse Park transform (i.e., dq / αβ transform, inverse Park transform) to obtain the stable output voltage value of the grid-connected converter in a two-phase stationary coordinate system (including the stable output voltage value of the grid-connected converter along the α-axis in a two-phase stationary coordinate system). and β-axis output voltage stability ).

[0078] Based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system ( and The reference values ​​of the filter inductor current in the two-phase stationary coordinate system (including the reference value of the α-axis current of the filter inductor in the two-phase stationary coordinate system) and the reference values ​​of the filter inductor current in the two-phase stationary coordinate system. and β-axis current reference value Calculate the actual output voltage value of the grid-connected converter in a two-phase stationary coordinate system (including the actual output voltage value of the α-axis of the grid-connected converter in a two-phase stationary coordinate system). and the actual value of the β-axis output voltage ).

[0079] Actual output voltage of a grid-connected converter in a two-phase stationary coordinate system and Modulation (such as SVPWM modulation) is performed to obtain the control signal.

[0080] The grid-connected converter is controlled according to the control signal.

[0081] Furthermore, based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system ( and The reference values ​​of the filter inductor current in the two-phase stationary coordinate system (including the reference value of the α-axis current of the filter inductor in the two-phase stationary coordinate system) and the reference values ​​of the filter inductor current in the two-phase stationary coordinate system. and β-axis current reference value Calculate the actual output voltage value of the grid-connected converter in a two-phase stationary coordinate system (including the actual output voltage value of the α-axis of the grid-connected converter in a two-phase stationary coordinate system). and the actual value of the β-axis output voltage This includes: performing a Clarke transform on the actual voltage value of the primary winding to obtain the actual α-axis voltage value of the primary winding in a two-phase stationary coordinate system. and actual value of β-axis voltage .

[0082] By performing a Clarke transform on the actual current value of the filter inductor, the actual α-axis current value of the filter inductor in a two-phase stationary coordinate system is obtained. and actual value of β-axis current .

[0083] Referring to Figure 3, based on the α-axis output voltage stability value of the grid-connected converter in the two-phase stationary coordinate system... and β-axis output voltage stability Reference value of α-axis voltage of primary winding in two-phase stationary coordinate system and β-axis voltage reference value Actual value of α-axis voltage of primary winding in two-phase stationary coordinate system and actual value of β-axis voltage The actual values ​​of the α-axis current and β-axis current of the filter inductor in a two-phase stationary coordinate system, and the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. and β-axis current reference value Calculate the actual value of the α-axis output voltage of the grid-connected converter in a two-phase stationary coordinate system. and the actual value of the β-axis output voltage .

[0084] Optionally, the actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual α-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable output voltage value along the α-axis of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second-state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

[0085] In this embodiment, the active power reference value of the grid-connected converter is set to 1MW, the line voltage of the AC grid is 35kV, and the turns ratio of the transformer (which can be a Y-Δ transformer) is 690V / 35kV. The control method provided in this application can obtain the voltage waveform diagrams of the primary winding as shown in Figures 5a and 5b, and the current waveform diagrams as shown in Figures 5c and 5d. In Figures 5a and 5b, the vertical axis represents the actual voltage value u of the primary winding. Ca u Cb u Cc The unit can be volts; the horizontal axis represents time (the unit can be seconds). In Figures 5c and 5d, the vertical axis represents the actual value of the primary winding current i. 2a i 2b i 2c The unit can be amperes (A); the horizontal axis represents time (the unit can be seconds).

[0086] Performing Fourier transforms on the voltage and current of the primary winding yields the voltage waveform shown in Figure 6a and the current waveform shown in Figure 6b. In Figure 6a, the vertical axis represents the percentage of harmonic amplitude to fundamental amplitude of the actual A-phase voltage of the primary winding in each frequency band; the horizontal axis represents the frequency. The fundamental amplitude of the actual A-phase voltage of the primary winding is 563.3V, and the total harmonic distortion (THD) is 2.22%. In Figure 6b, the vertical axis represents the percentage of harmonic amplitude to fundamental amplitude of the actual A-phase current of the primary winding in each frequency band; the horizontal axis represents the frequency. The fundamental amplitude of the actual A-phase current of the primary winding is 1233A, and the THD is 1.07%.

[0087] As can be seen from Figures 5a, 5b, 5c, 5d, 6a, and 6b, the voltage and current of the primary winding are both sinusoidal waves, and they satisfy the following conditions: total harmonic distortion rate is less than 5%, odd harmonic distortion rate is less than 4%, even harmonic distortion rate is 2%, and the DC component accounts for less than 0.5%. This meets the grid connection requirements of the grid-connected converter and verifies the feasibility of the control method provided in the above embodiments of this application.

[0088] Example 2: Based on the same inventive concept, this application also provides a control device for a grid-connected converter. As shown in Figure 1, the grid-connected converter 10 can be connected to the transformer 30 via a filter 20. The filter 20 may include a filter capacitor C and a filter inductor L. The transformer may include a primary winding 31 and a secondary winding 32. The primary winding 31 is connected to the filter, and the secondary winding 32 is connected to the AC power grid G. dc This represents the DC-side voltage of the grid-connected converter 10, u. vsca u vscb u vscc i represents the actual output voltage value of the grid-connected converter 10. La i Lb i Lc u represents the actual value of the current in the filter inductor. Ca u Cb u Cc i represents the actual voltage value of the primary winding. Ca i Cb i Cc i represents the actual current value of the filter capacitor. 2a i 2b i 2c u represents the actual value of the current in the primary winding. 2a u 2b u 2c i represents the actual voltage value of the secondary winding. ga i gb i gcThis represents the actual value of the current in the AC power grid. In this embodiment, only the inductance L of the AC power grid is considered. g u ga u gb u gc This indicates the actual voltage value of the AC power grid.

[0089] As shown in Figure 7, the control device 200 may include: a first determining module 201, used to determine the stable output voltage value (including the stable output voltage value of the d-axis) of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding and the voltage reference value of the primary winding in the transformer. and q-axis output voltage stability ).

[0090] The second determining module 202 is used to determine the reference current value (including the α-axis current reference value) of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual three-phase current value of the primary winding in the transformer and the reference voltage value of the primary winding. and β-axis current reference value ).

[0091] The control module 203 is used to control the grid-connected converter based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the current reference value of the filter inductor in the two-phase stationary coordinate system.

[0092] In some possible implementations, the first determining module 201 is specifically used to: perform Park transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current values ​​of the primary winding in a two-phase rotating coordinate system. and actual value of q-axis current .

[0093] Referring to Figure 3, based on the actual d-axis current value of the primary winding in a two-phase rotating coordinate system... Actual value of q-axis current d-axis voltage reference value and q-axis voltage reference value Calculate the d-axis output voltage stability of a grid-connected converter in a two-phase rotating coordinate system. and q-axis output voltage stability .

[0094] Optionally, the stable value of the d-axis output voltage of the grid-connected converter in a two-phase rotating coordinate system satisfies:

[0095] in, This represents the stable d-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This indicates the capacitance value of the filter capacitor in the filter.

[0096] The q-axis output voltage stability value of a grid-connected converter in a two-phase rotating coordinate system satisfies:

[0097] in, This represents the stable q-axis output voltage value of a grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

[0098] In some other possible implementations, the second determining module 202 is specifically used to: perform a Parker transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current values ​​of the primary winding in a two-phase rotating coordinate system. and actual value of q-axis current .

[0099] Referring to Figure 4, based on the actual d-axis current value of the primary winding in a two-phase rotating coordinate system... and q-axis voltage reference value Calculate the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. Based on the actual value of the q-axis current of the primary winding in a two-phase rotating coordinate system and d-axis voltage reference value Calculate the reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system. .

[0100] Reference value of d-axis current of filter inductor in two-phase rotating coordinate system and q-axis current reference value Performing an inverse Park transform (i.e., abc / αβ transform, inverse Park transform) yields the current reference value of the filter inductor in the two-phase stationary coordinate system (including the α-axis current reference value of the filter inductor in the two-phase stationary coordinate system). and β-axis current reference value ).

[0101] Optionally, the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This indicates the capacitance value of the filter capacitor in the filter.

[0102] The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system satisfies: .in, Reference value of q-axis current of filter inductor in two-phase rotating coordinate system This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the reference value of the d-axis voltage of the primary winding in a two-phase rotating coordinate system.

[0103] In some other possible implementations, the control module 203 is specifically used to: refer to Figure 3, stabilize the output voltage of the grid-connected converter in a two-phase rotating coordinate system (including the d-axis output voltage stability value of the grid-connected converter in a two-phase rotating coordinate system). and q-axis output voltage stability Perform an inverse Park transform (i.e., dq / αβ transform, inverse Park transform) to obtain the stable output voltage value of the grid-connected converter in a two-phase stationary coordinate system (including the stable output voltage value of the grid-connected converter along the α-axis in a two-phase stationary coordinate system). and β-axis output voltage stability ).

[0104] Based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system ( and The reference values ​​of the filter inductor current in the two-phase stationary coordinate system (including the reference value of the α-axis current of the filter inductor in the two-phase stationary coordinate system) and the reference values ​​of the filter inductor current in the two-phase stationary coordinate system. and β-axis current reference value Calculate the actual output voltage value of the grid-connected converter in a two-phase stationary coordinate system (including the actual output voltage value of the α-axis of the grid-connected converter in a two-phase stationary coordinate system). and the actual value of the β-axis output voltage ).

[0105] Actual output voltage of a grid-connected converter in a two-phase stationary coordinate system and Modulation (such as SVPWM modulation) is performed to obtain the control signal.

[0106] The grid-connected converter is controlled according to the control signal.

[0107] Furthermore, the control module 203 is specifically used to: perform a Clarke transformation on the actual voltage value of the primary winding to obtain the actual α-axis voltage value of the primary winding in a two-phase stationary coordinate system. and actual value of β-axis voltage .

[0108] By performing a Clarke transform on the actual current value of the filter inductor, the actual α-axis current value of the filter inductor in a two-phase stationary coordinate system is obtained. and actual value of β-axis current .

[0109] Referring to Figure 3, based on the α-axis output voltage stability value of the grid-connected converter in the two-phase stationary coordinate system... and β-axis output voltage stability Reference value of α-axis voltage of primary winding in two-phase stationary coordinate system and β-axis voltage reference value Actual value of α-axis voltage of primary winding in two-phase stationary coordinate system and actual value of β-axis voltage The actual values ​​of the α-axis current and β-axis current of the filter inductor in a two-phase stationary coordinate system, and the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. and β-axis current reference value Calculate the actual value of the α-axis output voltage of the grid-connected converter in a two-phase stationary coordinate system. and the actual value of the β-axis output voltage .

[0110] Optionally, the actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual α-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable output voltage value along the α-axis of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second-state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage of a grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of a grid-connected converter in a two-phase stationary coordinate system. This represents the reference value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

[0111] Example 3: Based on the same inventive concept, this application also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the control method provided in the above embodiments.

[0112] Example 4: Based on the same inventive concept, this application also provides a computer-readable storage medium, specifically a computer-readable storage medium (Memory). A computer-readable storage medium is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the control method provided in the above embodiments.

[0113] Those skilled in the art will understand that the embodiments of the application can be provided as a method, system, or computer program product. Therefore, the application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0114] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0115] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0116] 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, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0117] The above are merely examples of the application and are not intended to limit the application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the application shall be included within the scope of the claims of the pending application.

Claims

1. A control method for a grid-connected converter, characterized in that, The grid-connected converter is connected to the transformer via a filter. The control method includes: determining the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding of the transformer and the reference voltage value of the primary winding; determining the reference current value of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual three-phase current value of the primary winding of the transformer and the reference voltage value of the primary winding; and controlling the grid-connected converter based on the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system and the reference current value of the filter inductor in a two-phase stationary coordinate system.

2. The control method according to claim 1, characterized in that, The step of determining the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding and the voltage reference value of the primary winding includes: performing a Parker transformation on the actual three-phase current value of the primary winding to obtain the actual d-axis current value and q-axis current value of the primary winding in a two-phase rotating coordinate system; and calculating the stable d-axis output voltage value and q-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual d-axis current value, q-axis current value, d-axis voltage reference value, and q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system.

3. The control method according to claim 2, characterized in that, The stable value of the d-axis output voltage of the grid-connected converter in the two-phase rotating coordinate system satisfies: ;in, This represents the stable d-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This represents the capacitance value of the filter capacitor in the filter; the stable q-axis output voltage value of the grid-connected converter in the two-phase rotating coordinate system satisfies: in, This represents the stable q-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

4. The control method according to claim 1, characterized in that, The step of determining the reference current value of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual three-phase current value of the primary winding in the transformer and the reference voltage value of the primary winding includes: performing a Parker transformation on the actual three-phase current value of the primary winding to obtain the actual d-axis current value and q-axis current value of the primary winding in a two-phase rotating coordinate system; calculating the reference d-axis current value of the filter inductor in a two-phase rotating coordinate system based on the actual d-axis current value and q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system; calculating the reference q-axis current value of the filter inductor in a two-phase rotating coordinate system based on the actual q-axis current value and d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system; and performing an inverse Parker transformation on the reference d-axis current value and q-axis current value of the filter inductor in a two-phase rotating coordinate system to obtain the reference current value of the filter inductor in a two-phase stationary coordinate system.

5. The control method according to claim 4, characterized in that, The reference value of the d-axis current of the filter inductor in the two-phase rotating coordinate system satisfies: ;in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current value of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the capacitance value of the filter capacitor in the filter; the reference value of the q-axis current of the filter inductor in the two-phase rotating coordinate system satisfies: ;in, The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system.

6. The control method according to claim 1, characterized in that, The step of controlling the grid-connected converter based on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system includes: performing an inverse Park transform on the stable output voltage value of the grid-connected converter in the two-phase rotating coordinate system to obtain the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system; calculating the actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system; modulating the actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system to obtain a control signal; and controlling the grid-connected converter according to the control signal.

7. The control method according to claim 6, characterized in that, The calculation of the actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference current value of the filter inductor in the two-phase stationary coordinate system includes: performing a Clarke transform on the actual voltage value of the primary winding to obtain the actual α-axis voltage value and β-axis voltage value of the primary winding in the two-phase stationary coordinate system; performing a Clarke transform on the actual current value of the filter inductor to obtain the actual α-axis current value and β-axis current value of the filter inductor in the two-phase stationary coordinate system; and calculating the actual output voltage value of the grid-connected converter in the two-phase stationary coordinate system based on the stable output voltage value of the grid-connected converter in the two-phase stationary coordinate system and the reference .... The actual values ​​of the α-axis and β-axis output voltages of the grid-connected converter in the two-phase stationary coordinate system are calculated using the following parameters: the stable α-axis and β-axis output voltages of the primary winding in the two-phase stationary coordinate system; the actual α-axis and β-axis voltages of the primary winding in the two-phase stationary coordinate system; the actual α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system; and the reference α-axis and β-axis currents of the filter inductor in the two-phase stationary coordinate system.

8. The control method according to claim 7, characterized in that, The actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual value of the α-axis output voltage of the grid-connected converter in a two-phase stationary coordinate system. This represents the stable α-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the α-axis voltage reference value of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the β-axis voltage reference value of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

9. A control device for a grid-connected converter, characterized in that, The grid-connected converter is connected to the transformer via a filter. The control device includes: a first determining module, used to determine the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual three-phase current value of the primary winding of the transformer and the voltage reference value of the primary winding; a second determining module, used to determine the current reference value of the filter inductor in the filter in a two-phase stationary coordinate system based on the actual three-phase current value of the primary winding of the transformer and the voltage reference value of the primary winding; and a control module, used to control the grid-connected converter based on the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system and the current reference value of the filter inductor in a two-phase stationary coordinate system.

10. The control device according to claim 9, characterized in that, The first determining module is specifically used to: perform Parker transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current value and q-axis current value of the primary winding in a two-phase rotating coordinate system; and calculate the stable d-axis output voltage value and q-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system based on the actual d-axis current value, q-axis current value, d-axis voltage reference value, and q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system.

11. The control device according to claim 10, characterized in that, The stable value of the d-axis output voltage of the grid-connected converter in the two-phase rotating coordinate system satisfies: ;in, This represents the stable d-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the inductance value of the filter inductor. This represents the capacitance value of the filter capacitor in the filter; the stable q-axis output voltage value of the grid-connected converter in the two-phase rotating coordinate system satisfies: in, This represents the stable q-axis output voltage value of the grid-connected converter in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This represents the actual value of the d-axis current of the primary winding in a two-phase rotating coordinate system.

12. The control device according to claim 9, characterized in that, The second determining module is specifically used for: performing a Parker transformation on the actual three-phase current values ​​of the primary winding to obtain the actual d-axis current and q-axis current values ​​of the primary winding in a two-phase rotating coordinate system; calculating the d-axis current reference value of the filter inductor in a two-phase rotating coordinate system based on the actual d-axis current and q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system; and calculating the q-axis current reference value of the filter inductor in a two-phase rotating coordinate system based on the actual q-axis current and d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. The current reference values ​​of the filter inductor in the d-axis and q-axis in the two-phase rotating coordinate system are subjected to inverse Park transform to obtain the current reference value of the filter inductor in the two-phase stationary coordinate system.

13. The control device according to claim 12, characterized in that, The reference value of the d-axis current of the filter inductor in the two-phase rotating coordinate system satisfies: ;in, This represents the reference value of the d-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual d-axis current value of the primary winding in a two-phase rotating coordinate system. This represents the q-axis voltage reference value of the primary winding in a two-phase rotating coordinate system. This indicates the rated angular frequency of the AC power grid connected to the grid-connected converter. This represents the capacitance value of the filter capacitor in the filter; the reference value of the q-axis current of the filter inductor in the two-phase rotating coordinate system satisfies: ;in, The reference value of the q-axis current of the filter inductor in a two-phase rotating coordinate system. This represents the actual q-axis current of the primary winding in a two-phase rotating coordinate system. This represents the d-axis voltage reference value of the primary winding in a two-phase rotating coordinate system.

14. The control device according to claim 9, characterized in that, The control module is specifically used for: performing an inverse Park transform on the stable output voltage value of the grid-connected converter in a two-phase rotating coordinate system to obtain the stable output voltage value of the grid-connected converter in a two-phase stationary coordinate system; calculating the actual output voltage value of the grid-connected converter in a two-phase stationary coordinate system based on the stable output voltage value of the grid-connected converter in a two-phase stationary coordinate system and the current reference value of the filter inductor in a two-phase stationary coordinate system; modulating the actual output voltage value of the grid-connected converter in a two-phase stationary coordinate system to obtain a control signal; and controlling the grid-connected converter according to the control signal.

15. The control device according to claim 14, characterized in that, The control module is specifically used for: performing a Clarke transformation on the actual voltage value of the primary winding to obtain the actual α-axis voltage value and β-axis voltage value of the primary winding in a two-phase stationary coordinate system; performing a Clarke transformation on the actual current value of the filter inductor to obtain the actual α-axis current value and β-axis current value of the filter inductor in a two-phase stationary coordinate system; and calculating the actual α-axis output voltage value and β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system based on the stable α-axis output voltage value and β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system, the reference α-axis voltage value and β-axis voltage value of the primary winding in a two-phase stationary coordinate system, the actual α-axis voltage value and β-axis voltage value of the primary winding in a two-phase stationary coordinate system, the actual α-axis current value and β-axis current value of the filter inductor in a two-phase stationary coordinate system, and the reference α-axis current value and β-axis current value of the filter inductor in a two-phase stationary coordinate system.

16. The control device according to claim 15, characterized in that, The actual value of the α-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual value of the α-axis output voltage of the grid-connected converter in a two-phase stationary coordinate system. This represents the stable α-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the α-axis voltage reference value of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the α-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the α-axis current of the filter inductor in a two-phase stationary coordinate system. Represents the first-state feedback coefficient. This represents the second state feedback coefficient; the actual value of the β-axis output voltage of the grid-connected converter in the two-phase stationary coordinate system satisfies: ;in, This represents the actual β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the stable β-axis output voltage value of the grid-connected converter in a two-phase stationary coordinate system. This represents the β-axis voltage reference value of the primary winding in a two-phase stationary coordinate system. This represents the actual value of the β-axis voltage of the primary winding in a two-phase stationary coordinate system. This represents the reference value of the β-axis current of the filter inductor in a two-phase stationary coordinate system. This represents the actual value of the β-axis current of the filter inductor in a two-phase stationary coordinate system.

17. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the control method as described in any one of claims 1 to 8 is implemented.

18. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the control method as described in any one of claims 1 to 8.

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