A method and system for optimizing design of AC side inductance parameters of a network-forming converter

Abstract

The application provides a network-constructing type converter AC side inductance parameter optimization design method and system, the method comprises the following steps: designing the upper limit value of the AC side inductance parameter according to the four-quadrant operation requirement of the converter, designing the lower limit value of the AC side inductance parameter according to the total harmonic distortion rate index of the converter output current; optimizing the upper limit and the lower limit of the AC side inductance parameter within the fluctuation range allowed by the AC power grid frequency; optimizing the lower limit of the AC side inductance parameter according to the transfer function relationship between the DC voltage of the network-constructing type converter and the AC grid voltage; optimizing the upper limit of the AC side inductance parameter according to the transfer function relationship between the DC voltage of the network-constructing type converter and the active power fluctuation; determining the upper limit and the lower limit value of the AC side inductance parameter of the network-constructing type converter, and taking the intersection as the optimized value range of the AC side inductance parameter. The application can reduce the fluctuation degree of the DC bus voltage of the network-constructing type converter and improve the operation performance of the network-constructing type converter.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, specifically to a method and system for optimizing the design of AC side inductance parameters of a grid-connected converter. Background Technology

[0002] With the large-scale integration of new energy sources into modern power systems, the proportion of power electronic equipment, represented by grid-type converters (voltage source converters), is increasing. However, with changing control objectives, using the same parameters for the AC side inductor as those for grid-type converters presents problems. Summary of the Invention

[0003] Considering the relationship between the DC-side voltage, AC-side voltage, frequency, and active power of a grid-connected converter, this invention provides an optimized design method for the AC-side inductor parameters of a grid-connected converter, building upon the existing design method for these parameters. This method, based on traditional grid-connected converter inductor parameter design methods, further considers the impact of AC grid frequency, voltage, and active power fluctuations on the DC bus voltage of the grid-connected converter, thus determining the optimal range of inductor parameter values.

[0004] According to a first aspect of the present invention, a method for optimizing the design of AC side inductance parameters of a grid-type converter is provided, comprising: The upper limit value of the AC side inductance parameter is designed based on the four-quadrant operation requirements of the converter. L f_max1 The lower limit value of the AC side inductance parameter is designed based on the total harmonic distortion rate index of the converter output current. L f_min1 ; Based on the transfer function relationship between the DC bus voltage and the AC grid frequency of the grid-type converter, the upper limit of the AC side inductance parameter is optimized within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 ; Optimize the lower limit of AC side inductor parameters based on the transfer function relationship between DC voltage and AC grid voltage of grid-type converter. L f_min3 ; Optimize the upper limit of AC side inductance parameters based on the transfer function relationship between DC voltage and active power fluctuations in a grid-type converter. L f_max3 ; Based on the above design method, the upper and lower limits of the AC side inductance parameters of the grid-type converter are determined, and their intersection is taken as the optimized range of AC side inductance parameters.

[0005] Optionally, the grid-type converter includes: the converter main circuit consists of a three-phase two-level VSC and an AC-side inductor. L f The three-phase two-level VSC consists of AC-side capacitors and DC-side capacitors. It contains six IGBT switching modules. Each phase consists of two IGBT switching modules connected in series. The AC port is led out from the middle point and connected to the LC filter. The DC side of the VSC consists of a DC current source and a capacitor connected in parallel.

[0006] Optionally, the upper limit value of the AC side inductance parameter is designed according to the four-quadrant operation requirements of the converter. L f_max1 ,include: Determine the upper limit of the AC side inductance based on the active and reactive power parameters. L fP and L fQ ; L f_max1 Take the upper limit L fP and L fQ The smaller value in the range.

[0007] Optionally, the lower limit value of the AC side inductance parameter is designed based on the total harmonic distortion rate index of the converter output current. L f_min1 ,include: The lower limit of the AC side inductance is determined based on the total harmonic distortion (THD) index of the converter output current. L f_min1 As shown in equation (4): (4) In the formula, d % represents the total harmonic distortion rate of the grid-side current. I 1 represents the effective value of the fundamental frequency current. V n Represents the output voltage of the converter n Effective value of subharmonic voltage oh n represent n Second harmonic angular frequency.

[0008] Optionally, based on the transfer function relationship between the DC bus voltage of the grid-connected converter and the AC grid frequency, the upper limit of the AC side inductance parameter is optimized within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 ,include: DC-side voltage variation Δ of grid converterU dc With AC power grid frequency change Δ oh g The relationship is shown in equation (5): (5) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. oh g The amplitude representing the frequency change of the AC power grid. G dcω Representing different types of network control Δ U dc With Δ oh g Relationship; For grid-type converters with matched control, G dcω The expression for is shown in equation (6): (6) in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the angular frequency of the power grid. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = oh 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage change is set to Δ U dc_thω Δ oh g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (7), |Δ oh g | Represents the absolute value of the frequency change in the AC power grid: (7) in: (8) The upper limit of the AC side inductance is obtained from the above formula. L f_max2 and lower limit L f_min2 As shown in equation (9): (9).

[0009] Optionally, the lower limit of optimizing the AC-side inductance parameters based on the transfer function relationship between the DC voltage of the grid-connected converter and the AC grid voltage is... L f_min3 ,include: DC-side voltage variation Δ of grid converter U dc With AC grid voltage change Δ E g The relationship is shown in equation (10): (10) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. E g Represents the amplitude of the AC mains voltage change. G dcE Representing different types of network control Δ U dc With Δ E g Relationship; For grid-type converters employing matched control G dcE The expression is shown in equation (11): (11) in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L gFor the inductance of the AC power grid, X = oh 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage change is set to Δ U dc_thE ,|Δ E g | represents the absolute value of the frequency change of the AC power grid, Δ E g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (12): (12) in: (13) Based on the above formula, the lower limit of the AC side inductance is obtained as shown in equation (14): (14).

[0010] Optionally, the upper limit of the AC-side inductance parameter optimization based on the transfer function relationship between the DC voltage and active power fluctuation of the grid-connected converter is... L f_max3 ,include: DC voltage variation Δ of grid converter U dc With the change in active power Δ P g The relationship is shown in equation (15): (15) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. P g The magnitude of the change in active power. G dcP Representing different types of network control Δ U dc With Δ P g Relationship; Taking a grid-type converter with matched control as an example, G dcP The expression is shown in equation (16): (16) in:U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = oh 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage conversion is set to Δ. U dc_thP ,|Δ P g | represents the absolute value of the change in active power, Δ P g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (17): (17) in: (18) Based on the above formula, the upper limit of the AC side inductance can be obtained as shown in formula (19): (19).

[0011] Optionally, determining the upper and lower limits of the AC side inductance parameters of the grid-type converter, and taking their intersection as the optimized range of AC side inductance parameters, includes: The upper and lower limits of the AC side inductance parameters of the grid-type converter are determined, and the optimal range of AC side inductance parameters is determined, as shown in Equation (20).

[0012] (20).

[0013] A second aspect of the present invention provides a system for optimizing the inductance parameters of the AC side of a grid-type converter, comprising: First design module: Design the upper limit value of the AC side inductance parameter based on the four-quadrant operation requirements of the converter. L f_max1 ; Second design module: Design the lower limit value of AC side inductor parameters based on the total harmonic distortion index of the converter output current. L f_min1 ; The first optimization module: Based on the transfer function relationship between the DC bus voltage of the grid-type converter and the AC grid frequency, optimize the upper limit of the AC side inductance parameters within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 ; The second optimization module optimizes the lower limit of the AC side inductor parameters based on the transfer function relationship between the DC voltage of the grid converter and the AC grid voltage. L f_min3 ; The third optimization module optimizes the upper limit of the AC side inductance parameters based on the transfer function relationship between the DC voltage and active power fluctuations of the grid-type converter. L f_max3 ; Final determination module: Based on the results obtained from the above modules, determine the upper and lower limits of the AC side inductance parameters of the grid-type converter, and take their intersection as the optimized range of AC side inductance parameters.

[0014] A third aspect of the present invention provides a parameter optimization device, comprising: At least one memory for storing program instructions; At least one processor is used to call program instructions stored in the memory and execute the steps of the above-described method for optimizing the AC side inductor parameters of a grid-type converter according to the obtained program instructions.

[0015] The above-mentioned method for optimizing the AC side inductor parameters of a grid-type converter, while taking into account the harmonic attenuation rate and four-quadrant operation requirements, further considers the impact of AC grid frequency, voltage, and active power fluctuations on the DC bus voltage of the grid-type converter, determines the optimized range of AC side inductor parameters, and can reduce the fluctuation of the DC bus voltage of the grid-type converter and improve the operating performance of the grid-type converter. Attached Figure Description

[0016] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of a method for optimizing the inductance parameters of an AC side grid converter according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the main circuit of a three-phase grid converter in one embodiment of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0019] like Figure 1 As shown, this invention provides an embodiment of a method for optimizing the design of AC side inductance parameters in a grid-type converter, specifically including the following steps: S100, the upper limit value of the AC side inductance parameter is designed according to the four-quadrant operation requirements of the converter. L f_max1 ; S200, design the lower limit value of AC side inductance parameters based on the total harmonic distortion rate index of the converter output current. L f_min1 ; S300 optimizes the upper limit of the AC side inductance parameters within the allowable fluctuation range of the AC grid frequency, based on the transfer function relationship between the DC bus voltage and the AC grid frequency of the grid-type converter. L f_max2 and lower limit L f_min2 ; S400 optimizes the lower limit of AC side inductance parameters based on the transfer function relationship between the DC voltage of the grid-connected converter and the AC grid voltage. L f_min3 ; S500 optimizes the upper limit of AC side inductance parameters based on the transfer function relationship between DC voltage and active power fluctuations in grid-connected converters. L f_max3 ; S600, based on the above design method, determine the upper and lower limits of the AC side inductance parameters of the grid-type converter, and take their intersection as the optimized range of AC side inductance parameters.

[0020] This invention discloses an optimized design method for AC-side inductor parameters of a grid-type converter. While taking into account harmonic attenuation rate and four-quadrant operation requirements, it further considers the impact of AC grid frequency, voltage, and active power fluctuations on the DC bus voltage of the grid-type converter, determines the optimized range of AC-side inductor parameters, and can reduce the fluctuation of DC bus voltage of the grid-type converter, thereby improving the operating performance of the grid-type converter.

[0021] In a preferred embodiment of the present invention, reference is made to... Figure 2 As shown, the main circuit of the grid-type converter consists of a three-phase two-level VSC and an AC-side inductor. L f The three-phase two-level VSC consists of AC-side capacitors and DC-side capacitors. It contains six IGBT switching modules, with each phase consisting of two IGBT switching modules connected in series. An AC port is led out from the midpoint and connected to an LC filter. The DC side of the VSC consists of a DC current source and a capacitor connected in parallel.

[0022] In a preferred embodiment of the present invention, in step S100, the upper limit of the AC side inductance parameter is designed based on the four-quadrant operation function of the converter. L f_max1 ,include: S101, In order to meet the four-quadrant operation function of the converter, the upper limit of the AC side inductance is determined according to the active power index. L fP As shown in equation (1).

[0023] (1) In the formula: E m Represents the electric potential within the power grid. f Represents the AC power factor angle. V dc Represents the DC side voltage. oh 1 represents the fundamental angular frequency. P It represents active power.

[0024] S102, In order to meet the four-quadrant operation function of the converter, the upper limit of the AC side inductance is determined according to the reactive power index. L fQ As shown in equation (2).

[0025] (2) In the formula: E m Represents the electric potential within the power grid. f Represents the AC power factor angle. V dc Represents the DC side voltage. oh 1 represents the fundamental angular frequency. Q Represents reactive power.

[0026] S103, L f_max1 Take the smaller value of the two, as shown in equation (3). (3) In a preferred embodiment of the present invention, step S200 is implemented to design the lower limit of the AC side inductance parameters based on the total harmonic distortion index of the converter output current. L f_min1 ,include: S201, determine the lower limit of the AC side inductance based on the total harmonic distortion rate index of the converter output current. L f_min1 As shown in equation (4).

[0027] (4) In the formula, d % represents the total harmonic distortion rate of the grid-side current. I 1 represents the effective value of the fundamental frequency current. V n Represents the output voltage of the converter n Effective value of subharmonic voltage oh n represent n Second harmonic angular frequency.

[0028] In a preferred embodiment of the present invention, step S300 is implemented to optimize the upper limit of the AC side inductance parameter based on the transfer function relationship between the DC side voltage of the grid-connected converter and the AC grid frequency. L f_max2 and lower limit L f_min2 ,include: S301, DC-side voltage change Δ of grid-type converter U dc With AC power grid frequency change Δ oh g The relationship is shown in equation (5): (5) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. oh g The amplitude representing the frequency change of the AC power grid. G dcω Representing different types of network control Δ U dc With Δ oh g The relationship.

[0029] S302, taking a grid-type converter with matched control as an example. G dcω The expression for is shown in equation (6): (6) in: Udc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = oh 0( L f + L g ), H C is the time constant of DC capacitor inertia.

[0030] S303, set the critical value for DC voltage change to Δ U dc_thω Δ oh g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (7), |Δ oh g | represents the absolute value of the frequency change of the AC power grid.

[0031] (7) in: (8) S304, according to the above formula, the upper limit of the AC side inductance can be obtained. L f_max2 and lower limit L f_min2 As shown in equation (9): (9) In a preferred embodiment of the present invention, step S400 is implemented to optimize the lower limit value of the AC side inductance parameter based on the transfer function relationship between the DC side voltage of the grid-connected converter and the AC grid voltage. L f_min3 ,include: S401, DC-side voltage change Δ of grid-type converter U dc With AC grid voltage change Δ Eg The relationship is shown in equation (10): (10) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. E g Represents the amplitude of the AC mains voltage change. G dcE Representing different types of network control Δ U dc With Δ E g The relationship.

[0032] S402, taking a grid-type converter with matched control as an example. G dcE The expression is shown in equation (11): (11) in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = oh 0( L f + L g ), H C is the time constant of DC capacitor inertia.

[0033] S403, set the critical value for DC voltage change to Δ U dc_thE ,|Δ E g | represents the absolute value of the frequency change of the AC power grid, Δ E g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (12).

[0034] (12) in: (13) S404, according to the above formula, the lower limit of the AC side inductance can be obtained as shown in formula (14): (14) In a preferred embodiment of the present invention, S500 is implemented to optimize the upper limit of the AC side inductance parameter based on the relationship between the DC voltage and active power fluctuation of the grid-connected converter. L f_max3 ,include: S501, DC voltage variation Δ of grid-type converter U dc With the change in active power Δ P g The relationship is shown in equation (15): (15) Where: Δ U dc Δ represents the magnitude of the change in DC voltage. P g The magnitude of the change in active power. G dcP Representing different types of network control Δ U dc With Δ P g The relationship.

[0035] S502, taking a grid-type converter with matched control as an example. G dcP The expression is shown in equation (16): (16) in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. oh 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. d This refers to the phase difference between the AC side voltage of the converter and the grid voltage. d 0 is d steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid,X = oh 0( L f + L g ), H C is the time constant of DC capacitor inertia.

[0036] S503 sets the critical value for DC voltage conversion to Δ. U dc_thP ,|Δ P g | represents the absolute value of the change in active power, Δ P g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (17): (17) in: (18) S504, according to the above formula, the upper limit of the AC side inductance can be obtained as shown in formula (19): (19) In a preferred embodiment of the present invention, S600 is implemented to determine the upper and lower limits of the AC side inductance parameters of the grid-type converter according to the above design method, thereby completing the optimization of the AC side inductance parameters, including: S601. Based on the above design method, determine the upper and lower limits of the AC side inductance parameters of the grid-type converter, determine the optimal range of the AC side inductance parameters, and complete the optimization of the AC side inductance parameters.

[0037] (20) Based on the same technical concept, in another embodiment of the present invention, a grid-type converter AC side inductance parameter optimization design system is also provided to implement the above-mentioned grid-type converter AC side inductance parameter optimization design method. Specifically, the system includes: First design module: Design the upper limit value of the AC side inductance parameter based on the four-quadrant operation requirements of the converter. L f_max1 ; Second design module: Design the lower limit value of AC side inductor parameters based on the total harmonic distortion index of the converter output current. L f_min1 ; The first optimization module: Based on the transfer function relationship between the DC bus voltage of the grid-type converter and the AC grid frequency, optimize the upper limit of the AC side inductance parameters within the allowable fluctuation range of the AC grid frequency. Lf_max2 and lower limit L f_min2 ; The second optimization module optimizes the lower limit of the AC side inductor parameters based on the transfer function relationship between the DC voltage of the grid converter and the AC grid voltage. L f_min3 ; The third optimization module optimizes the upper limit of the AC side inductance parameters based on the transfer function relationship between the DC voltage and active power fluctuations of the grid-type converter. L f_max3 ; Final determination module: Based on the results obtained from the above modules, determine the upper and lower limits of the AC side inductance parameters of the grid-type converter, and take their intersection as the optimized range of AC side inductance parameters.

[0038] Each module of the above-described embodiment of the grid-type converter AC side inductance parameter optimization design system corresponds to the steps of the grid-type converter AC side inductance parameter optimization design method. The specific implementation techniques can be referred to the implementation of the method steps in the above embodiments, and will not be repeated here.

[0039] In another embodiment of the present invention, a parameter optimization device is also provided, comprising: At least one memory for storing program instructions; At least one processor is configured to call program instructions stored in the memory and execute the steps of the AC side inductor parameter optimization design method for a grid-type converter as described in any of the above embodiments, according to the obtained program instructions.

[0040] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0041] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure oneOne or more processes and / or boxes Figure one A device that provides the functions specified in one or more boxes.

[0042] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure one One or more processes and / or boxes Figure one The function specified in one or more boxes.

[0043] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure one One or more processes and / or boxes Figure one The steps of the function specified in one or more boxes.

[0044] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0045] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for optimizing the design of AC side inductance parameters in a grid-type converter, characterized in that, include: The upper limit value of the AC side inductance parameter is designed based on the four-quadrant operation requirements of the converter. L f_max1 The lower limit value of the AC side inductance parameter is designed based on the total harmonic distortion rate index of the converter output current. L f_min1 ; Based on the transfer function relationship between the DC bus voltage and the AC grid frequency of the grid-type converter, the upper limit of the AC side inductance parameter is optimized within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 ; Optimize the lower limit of AC side inductor parameters based on the transfer function relationship between DC voltage and AC grid voltage of grid-type converter. L f_min3 ; Optimize the upper limit of AC side inductance parameters based on the transfer function relationship between DC voltage and active power fluctuations in a grid-type converter. L f_max3 ; Based on the above design method, the upper and lower limits of the AC side inductance parameters of the grid-type converter are determined, and their intersection is taken as the optimized range of AC side inductance parameters.

2. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The grid-type converter's main circuit consists of a three-phase two-level VSC and an AC-side inductor. L f It consists of AC-side capacitors and DC-side capacitors. The three-phase two-level VSC contains six IGBT switching modules. Each phase consists of two IGBT switching modules connected in series. The AC port is led out from the middle and connected to the LC filter. The DC side of the VSC consists of a DC current source and a capacitor connected in parallel.

3. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The upper limit value of the AC side inductance parameter is designed according to the four-quadrant operation requirements of the converter. L f_max1 ,include: Determine the upper limit of the AC side inductance based on the active and reactive power parameters. L fP and L fQ ; L f_max1 Take the upper limit L fP and L fQ The smaller value in the range.

4. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The lower limit value of the AC side inductor parameter is designed based on the total harmonic distortion index of the converter output current. L f_min1 ,include: The lower limit of the AC side inductance is determined based on the total harmonic distortion (THD) index of the converter output current. L f_min1 As shown in equation (4): （4） In the formula, δ % represents the total harmonic distortion rate of the grid-side current. I 1 represents the effective value of the fundamental frequency current. V n Represents the output voltage of the converter n Effective value of subharmonic voltage ω n represent n Second harmonic angular frequency.

5. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, Based on the transfer function relationship between the DC bus voltage of the grid-type converter and the AC grid frequency, the upper limit of the AC side inductance parameter is optimized within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 , include: DC-side voltage variation Δ of grid converter U dc With AC power grid frequency change Δ ω g The relationship is shown in equation (5): （5） Where: Δ U dc Δ represents the magnitude of the change in DC voltage. ω g The amplitude representing the frequency change of the AC power grid. G dcω Representing different types of network control Δ U dc With Δ ω g Relationship; For grid-type converters with matched control, G dcω The expression for is shown in equation (6): （6） in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. ω 0 is the reference value for the angular frequency of the power grid. δ This refers to the phase difference between the AC side voltage of the converter and the grid voltage. δ 0 is δ steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = ω 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage change is set to Δ U dc_thω Δ ω g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (7), |Δ ω g | Represents the absolute value of the frequency change in the AC power grid: （7） in: （8） The upper limit of the AC side inductance is obtained from the above formula. L f_max2 and lower limit L f_min2 As shown in equation (9): （9）。 6. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The lower limit for optimizing the AC side inductor parameters based on the transfer function relationship between the DC voltage of the grid converter and the AC grid voltage is described. L f_min3 , include: DC-side voltage variation Δ of grid converter U dc With AC grid voltage change Δ E g The relationship is shown in equation (10): （10） Where: Δ U dc Δ represents the magnitude of the change in DC voltage. E g Represents the amplitude of the AC mains voltage change. G dcE Representing different types of network control Δ U dc With Δ E g Relationship; For grid-type converters employing matched control G dcE The expression is shown in equation (11): （11） in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. ω 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. δ This refers to the phase difference between the AC side voltage of the converter and the grid voltage. δ 0 is δ steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = ω 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage change is set to Δ U dc_thE ,|Δ E g | represents the absolute value of the frequency change of the AC power grid, Δ E g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (12): （12） in: （13） Based on the above formula, the lower limit of the AC side inductance is obtained as shown in equation (14): （14）。 7. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The upper limit of the AC side inductance parameter is optimized based on the transfer function relationship between the DC voltage and active power fluctuation of the grid converter. L f_max3 ,include: DC voltage variation Δ of grid converter U dc With the change in active power Δ P g The relationship is shown in equation (15): （15） Where: Δ U dc Δ represents the magnitude of the change in DC voltage. P g The magnitude of the change in active power. G dcP Representing different types of network control Δ U dc With Δ P g Relationship; Taking a grid-type converter with matched control as an example, G dcP The expression is shown in equation (16): （16） in: U dc0 This is the steady-state value of the DC voltage. U t0 This represents the steady-state value of the AC side voltage of the converter. E g0 This represents the steady-state value of the AC voltage of the power grid. ω 0 is the reference value for the power grid angular frequency, i.e., 100π rad / s. δ This refers to the phase difference between the AC side voltage of the converter and the grid voltage. δ 0 is δ steady-state value, L f For the AC side inductance of the converter, L g For the inductance of the AC power grid, X = ω 0( L f + L g ), H C The time constant of DC capacitor inertia; The critical value for DC voltage conversion is set to Δ. U dc_thP ,|Δ P g | represents the absolute value of the change in active power, Δ P g When it changes, in order to make Δ U dc It should not exceed its critical value and should satisfy the relationship shown in equation (17): （17） in: （18） Based on the above formula, the upper limit of the AC side inductance can be obtained as shown in formula (19): （19）。 8. The method for optimizing the design of AC side inductance parameters of a grid-type converter according to claim 1, characterized in that, The determination of the upper and lower limits of the AC side inductance parameters of the grid-type converter, and the taking of their intersection as the optimized range of AC side inductance parameters, includes: The upper and lower limits of the AC side inductance parameters of the grid-type converter are determined, and the optimal range of values ​​for the AC side inductance parameters is determined, as shown in equation (20): （20）。 9. A system for optimizing the design of AC side inductance parameters in a grid-type converter, characterized in that, include: First design module: Design the upper limit value of the AC side inductance parameter based on the four-quadrant operation requirements of the converter. L f_max1 ; Second design module: Design the lower limit value of AC side inductor parameters based on the total harmonic distortion index of the converter output current. L f_min1 ; The first optimization module: Based on the transfer function relationship between the DC bus voltage of the grid-type converter and the AC grid frequency, optimize the upper limit of the AC side inductance parameters within the allowable fluctuation range of the AC grid frequency. L f_max2 and lower limit L f_min2 ; The second optimization module optimizes the lower limit of the AC side inductor parameters based on the transfer function relationship between the DC voltage of the grid converter and the AC grid voltage. L f_min3 ; The third optimization module optimizes the upper limit of the AC side inductance parameters based on the transfer function relationship between the DC voltage and active power fluctuations of the grid-type converter. L f_max3 ; Final determination module: Based on the results obtained from the above modules, determine the upper and lower limits of the AC side inductance parameters of the grid-type converter, and take their intersection as the optimized range of AC side inductance parameters.

10. A parameter optimization device, characterized in that, include: At least one memory for storing program instructions; At least one processor is configured to invoke program instructions stored in the memory and execute the steps of the method described in any one of claims 1-8 according to the obtained program instructions.

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