A control parameter identification method and system of a new energy unit grid-connected converter, a storage medium and a processor

Abstract

This invention relates to the field of grid connection technology for new energy power units, and particularly to a method, system, storage medium, and processor for identifying control parameters of a grid-connected converter for new energy power units. The method of this invention establishes a high-frequency impedance model of the grid-connected system of the new energy power unit and determines the parameters to be identified, including the proportional coefficient and integral coefficient of the converter's inner current loop, as well as the control delay of the converter. By applying harmonic voltage disturbances at different frequencies, the harmonic currents of the unit at different frequencies are measured, thereby obtaining impedance values ​​at three different frequencies. These three impedance values ​​are input into the high-frequency impedance model of the grid-connected system of the new energy power unit, and the parameters to be identified are solved by solving the high-frequency impedance model of the grid-connected system of the new energy power unit. The model involved in this invention has a low order, and the control parameters of the converter's inner current loop can be obtained through only a small number of impedance tests and equation solving, featuring high identification efficiency and high accuracy.

Description

Technical Field

[0001] This invention relates to the field of grid connection technology for new energy units, and in particular to a method, system, storage medium, and processor for identifying control parameters of grid-connected converters for new energy units. Background Technology

[0002] The grid connection of renewable energy power generation widely adopts power electronic devices, represented by grid-connected inverters. The multi-scale dynamic control of these devices interacts complexly with the weak grid, leading to frequent harmonic oscillations such as subsynchronous / supersynchronous oscillations and harmonic resonances, which seriously affect the safe and stable operation of the renewable energy power system. To further improve the renewable energy absorption rate and enhance the quality of renewable energy power, stability analysis of the renewable energy power system is necessary to ensure the safe operation of the power grid.

[0003] To accurately analyze the impact of large-scale renewable energy generating units and their power plants on the power system, it is necessary to construct a white-box model of the units that can characterize the dynamic and station-state characteristics of actual renewable energy generating units. The white-box model of the units has a complex structure, including multiple components such as inner and outer current loops, phase-locked loops, and fault ride-through control loops, with numerous parameters that interact and influence each other. While current parameter identification methods have conducted in-depth analyses of the fault ride-through control loop, they cannot accurately identify the current loop parameters, which are insensitive to the external characteristics of fault ride-through. Summary of the Invention

[0004] To address the shortcomings of current identification methods in accurately identifying current loop control parameters, this invention provides a control parameter identification method, system, storage medium, and processor for grid-connected converters in new energy power units. This invention identifies control parameters based on impedance external characteristics. Utilizing the high-frequency impedance characteristics of the converter, which are closely related only to the inner current loop, main circuit parameters, and control link delay parameters, the order of the identification model is significantly reduced while maintaining identification accuracy. The specific technical solution is as follows:

[0005] A method for identifying control parameters of a grid-connected converter for a new energy generating unit includes the following steps:

[0006] Step S1: Based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit, and the current inner loop control structure, establish a high-frequency impedance theoretical model of the converter that includes unknown quantities of the current inner loop parameters.

[0007] Step S2: Obtain the high-frequency impedance model of the new energy unit grid-connected system based on the high-frequency impedance theoretical model of the converter, and determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter ;

[0008] Step S3: Establish an impedance test module, apply harmonic voltage disturbances at different frequencies, measure the harmonic current of the unit at different frequencies, and then obtain the impedance values ​​at three different frequencies.

[0009] Step S4: Input the impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

[0010] Preferably, the establishment of the converter high-frequency impedance theoretical model including unknown parameters of the inner current loop in step S1 specifically includes the following steps:

[0011] Step S11: Establish the main circuit structure model and control model of the grid-connected converter for the new energy unit; wherein, the main circuit structure of the grid-connected converter for the new energy unit includes a DC / AC converter, an LCL filter, and a transformer connected in sequence, with the transformer connected to the power grid; the control model includes a voltage and current acquisition module, a current inner loop module, and a PWM module; the voltage and current acquisition module is connected to the LCL filter and the current inner loop module respectively; the current inner loop module is connected to the PWM module; the PWM module is connected to the DC / AC converter;

[0012] Step S12: The voltage and current acquisition module acquires the output current of the DC / AC converter and the voltage at the midpoint of the two inductors of the LCL filter; the inner current loop module obtains the modulation voltage of the PWM module based on the inner loop current reference value, the output current of the DC / AC converter, and the voltage at the midpoint of the two inductors of the LCL filter; the PWM module outputs a trigger pulse to the DC / AC converter based on the modulation voltage to control the output current of the DC / AC converter; the output current of the DC / AC converter is:

[0013] ;

[0014] in, This is the reference value for the inner loop current. This refers to the output current of the DC / AC converter. This is the voltage at the midpoint between the two inductors in the LCL filter; The filter inductor is located near the machine side of the LCL filter; To control the delay, among which For the control delay of the converter; Let be the transfer function of the PI controller in the current inner loop module, where This is the proportionality coefficient for the inner current loop. s represents the integral coefficient of the inner current loop; s is the Laplace operator; This is the impedance reference value for the DC / AC converter;

[0015] Step S13, will Iref When the fundamental current reference value is used, the theoretical model of the high-frequency impedance of the DC / AC converter is as follows:

[0016] .

[0017] Preferably, the high-frequency impedance model of the new energy unit grid connection system in step S2 is as follows:

[0018] ;

[0019] in, For the LCL filter capacitor, The filter inductor is located near the grid side of the LCL filter; This is the equivalent inductance of the transformer. This represents the transformer turns ratio; / / indicates parallel impedance connection.

[0020] Preferably, the impedance testing module in step S3 includes a voltage source unit and a current measurement unit. The voltage source unit is used to apply harmonic voltage disturbances at different frequencies, and the current measurement unit is used to measure the harmonic current of the unit at different frequencies.

[0021] Preferably, the harmonic voltage disturbance in step S3 Represented as:

[0022] ;

[0023] in, The amplitude of the disturbance value injected into the Nth harmonic. The frequency at which the disturbance value is injected for the Nth harmonic, h is the total number of harmonics; t is the time variable;

[0024] frequency impedance for:

[0025] ;

[0026] in, , Frequency Lower harmonic voltage component and harmonic current component.

[0027] Preferably, frequency The frequency values ​​are for the 1000Hz~1500Hz high-frequency band.

[0028] Preferably, ,in This is the fundamental frequency.

[0029] A control parameter identification system for a grid-connected converter of a new energy unit, using the method described above, includes:

[0030] The modeling module is used to establish a high-frequency impedance theoretical model of the converter, which includes unknown quantities of the current inner loop parameters, based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit and the current inner loop control structure.

[0031] The parameter identification module is used to obtain the high-frequency impedance model of the new energy unit grid-connected system based on the converter high-frequency impedance theoretical model, and to determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter ;

[0032] The impedance test module is used to apply harmonic voltage disturbances at different frequencies, measure the harmonic current of the unit at different frequencies, and thus obtain impedance values ​​at three different frequencies.

[0033] The parameter identification module is used to input impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

[0034] A computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute the control parameter identification method for a grid-connected converter of a new energy unit.

[0035] A processor for running a program, wherein the program executes the control parameter identification method for a grid-connected converter of a new energy unit.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] The method of this invention establishes a high-frequency impedance model of the grid-connected system of new energy generating units and determines the parameters to be identified, including the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter This invention involves applying harmonic voltage disturbances at different frequencies, measuring the harmonic currents of the generator unit at different frequencies, and obtaining impedance values ​​at three different frequencies. These impedance values ​​are then input into the high-frequency impedance model of the new energy generator grid-connected system. The high-frequency impedance model of the new energy generator grid-connected system is then solved to obtain the parameters to be identified. Based on the principle that the influence of the converter's outer loop control on the converter's high-frequency impedance characteristics can be ignored, this invention simplifies a high-order model of more than twenty orders to a low-order third-order model. The actual high-frequency impedance characteristics are then obtained through grid-connected impedance scanning. By comparing the theoretical impedance characteristics with the actual impedance characteristics, the current inner loop control parameters are identified. The model involved in this invention has a low order, and the control parameters of the converter's current inner loop can be obtained through only a small number of impedance tests and equation solving, exhibiting high identification efficiency and accuracy. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0039] Figure 1 This is a flowchart of the method of the present invention.

[0040] Figure 2 This is a schematic diagram of the main circuit structure of the grid-connected converter for a new energy power unit.

[0041] Figure 3 This is a schematic diagram of the physical equivalent circuit for grid connection of new energy generating units.

[0042] Figure 4 This is the schematic diagram of the original control model of the converter.

[0043] Figure 5 The simplified control model schematic diagram of the converter.

[0044] Figure 6 This is a schematic diagram of an impedance testing system for grid-connected new energy power units.

[0045] Figure 7 This is a comparison chart of the actual impedance and the identified impedance of a direct-drive wind turbine.

[0046] Figure 8 This is a system schematic diagram of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0049] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0050] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0051] Example 1:

[0052] like Figure 1 As shown in the figure, this embodiment provides a method for identifying control parameters of a grid-connected converter for a new energy unit, including the following steps:

[0053] Step S1: Based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit, and the current inner loop control structure, establish a high-frequency impedance theoretical model of the converter that includes unknown quantities of the current inner loop parameters.

[0054] Establishing a high-frequency impedance theoretical model for a converter that includes unknown parameters of the inner current loop specifically involves the following steps:

[0055] Step S11: Establish the main circuit structure model and control model of the grid-connected converter for the new energy unit; the main circuit structure of the grid-connected converter for the new energy unit includes a DC / AC converter, an LCL filter, and a transformer connected in sequence, with the transformer connected to the power grid; the control model includes a voltage and current acquisition module, a current inner loop module, and a PWM module; the voltage and current acquisition module is connected to the LCL filter and the current inner loop module respectively; the current inner loop module is connected to the PWM module; the PWM module is connected to the DC / AC converter.

[0056] Specifically, the LCL filter includes a filter inductor located near the machine side. Filter capacitor Filter inductor near the grid side Filter inductor One end is connected to the DC / AC converter, and the other end is connected to the filter capacitor. One end, filter inductor One end is connected to the filter capacitor. The other end is grounded, and the filter inductor The other end is connected to a transformer. The transformer is a box-type transformer with a turns ratio of k.

[0057] Figure 2 This is a schematic diagram of the grid connection of a new energy power unit's converter. Point A in the diagram is the unit's grid connection point. Looking from point A towards both the wind turbine and the power grid, we can see the following: Figure 3 The diagram shows the physical circuit diagram of the grid-connected equivalent impedance. Figure 3 In this context, the impedance Z on the new energy side is the grid connection impedance. The grid connection impedance Z reflects the transfer function relationship between voltage disturbances and current disturbances at different frequencies:

[0058] (1)

[0059] In the formula, voltage and current All are harmonic disturbance phasors.

[0060] Figure 4 The control model for the original converter typically uses a DC voltage control timescale of 1-10Hz, while the high-frequency oscillations of new energy sources range from hundreds to thousands of Hz. Therefore, when studying high-frequency oscillations, the DC bus voltage can be considered constant. Since the control bandwidths of the power and voltage outer loops are generally below 100Hz, they have almost no impact on high frequencies. Therefore, the outer loop control is ignored in the high-frequency impedance model of the converter. The simplified control model of the converter is as follows: Figure 5 As shown.

[0061] Step S12: The voltage and current acquisition module acquires the output current of the DC / AC converter. The voltage at the midpoint of the two inductors of the LCL filter The inner current loop module uses the inner loop current reference value. and the output current of the DC / AC converter The voltage at the midpoint of the two inductors of the LCL filter The modulation voltage of the PWM module is obtained; the PWM module outputs a trigger pulse to the DC / AC converter based on the modulation voltage, controlling the output current of the DC / AC converter; according to Figure 5 The output current of the DC / AC converter can be obtained as follows:

[0062] (2)

[0063] From the above formula, we can obtain:

[0064] (3)

[0065] in, This is the reference value for the inner loop current. This refers to the output current of the DC / AC converter. This is the voltage at the midpoint between the two inductors in the LCL filter; The filter inductor is located near the machine side of the LCL filter; To control the delay, among which For the control delay of the converter; Let be the transfer function of the PI controller in the current inner loop module, where This is the proportionality coefficient for the inner current loop. s represents the integral coefficient of the inner current loop; s is the Laplace operator; This is the impedance reference value for the DC / AC converter.

[0066] like Figure 5 As shown, specifically, the inner current loop module is the inner loop current reference value. and the output current of the DC / AC converter The difference between the feedback value and the input value is used to generate a modulation wave reference voltage through the proportional-integral stage of the inner current loop module. The modulation wave reference voltage is then compared with the voltage at the midpoint of the two inductors of the LCL filter. Summing yields the actual modulation voltage of the PWM module. Based on this modulation voltage, the PWM module outputs a trigger pulse to the DC / AC converter, controlling the switching transistors of the DC / AC converter to output the required current value. Where K... pwm The gain of the modulation stage is typically 1, G. Ts To control link delay, the output voltage of the converter and the voltage at the midpoint of the two inductors of the LCL filter are... The output current is applied to the filter inductor Lf1. .

[0067] Step S13, when ignoring the outer loop, will I ref When set as the fundamental reference value of the current, the fundamental reference value of the current is constant, and the left side of equation (3) is equivalent to a current source, according to Figure 3 Based on the equivalent circuit and the impedance definition of the converter shown, the theoretical model of the high-frequency impedance of the DC / AC converter can be obtained as follows:

[0068] (4)

[0069] Equation (4) can be transformed to obtain:

[0070] (5)

[0071] Step S2: Obtain the high-frequency impedance model of the new energy unit grid-connected system based on the high-frequency impedance theoretical model of the converter, and determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter The remaining parameters are all available, so impedance parameter values ​​for three frequencies are required.

[0072] The high-frequency impedance model of the grid-connected system for new energy generating units is as follows:

[0073] (6)

[0074] in, For the LCL filter capacitor, The filter inductor is located near the grid side of the LCL filter; This is the equivalent inductance of the transformer. This represents the transformer turns ratio; / / indicates parallel impedance, where the reciprocal of the total resistance in parallel is equal to the sum of the reciprocals of the individual resistances, i.e., 1 / R. 总 =1 / R1+1 / R2+……+1 / R n Specifically, the total value of the two resistors connected in parallel is: R = R1R2 / (R1 + R2). Where R... n This represents the nth resistor.

[0075] Step S3, establish the impedance test module, such as Figure 6 As shown, harmonic voltage disturbances at different frequencies are applied, and the harmonic currents of the unit at different frequencies are measured to obtain impedance values ​​at three different frequencies. The impedance test module includes a voltage source unit and a current measurement unit. The voltage source unit is used to apply harmonic voltage disturbances at different frequencies, and the current measurement unit is used to measure the harmonic currents of the unit at different frequencies.

[0076] Harmonic voltage disturbance Represented as:

[0077] (7)

[0078] in, The amplitude of the Nth harmonic injected disturbance value is typically selected as 0.5% to 2% of the rated voltage; The frequency of the disturbance value injected for the Nth harmonic, where N is the harmonic index, h is the total number of harmonics, and t is the time variable;

[0079] frequency impedance for:

[0080] (8)

[0081] in, , Frequency Lower harmonic voltage component and harmonic current component.

[0082] frequency The frequency values ​​are for the 1000Hz~1500Hz high-frequency band. It should be avoided to be an integer multiple of the fundamental frequency; it can be selected as... ,in This is the fundamental frequency.

[0083] Three frequencies can be obtained from step S3. impedance value , , .

[0084] Step S4: Input the impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

[0085] The three impedance values ​​obtained , , Inputting the high-frequency impedance model of the new energy unit grid-connected system yields a set of equations containing three parameters to be identified:

[0086] (8)

[0087] By solving the above three equations, the proportional gain of the converter's inner current loop can be obtained. Integral coefficient of the converter current inner loop and the control delay of the converter .

[0088] This embodiment uses a direct-drive wind turbine as an example for verification. The parameters of the direct-drive wind turbine are shown in Table 1.

[0089] Table 1 Parameters of Direct Drive Wind Turbine Units

[0090]

[0091] A simulation model of a single direct-drive wind turbine was built in PSCAD / EMTDC, and then a frequency scan was performed on the 500~3000Hz frequency range of the turbine. The control parameters to be identified include the converter current inner loop proportional gain.K p Integral coefficient of converter current inner loop K i and converter control delay T s The frequency impedances at three points—1040Hz, 1140Hz, and 1240Hz—were selected as reference values, resulting in three sets of equations. Solving these equations using MATLAB yielded three control parameter values ​​of 1.05, 46, and 245µs, with errors of 5%, 8%, and 4%, respectively. After identifying the controller parameters, a theoretical impedance model was established in MATLAB based on these parameters. Figure 7 To compare the identified impedance parameter with the actual impedance of the direct-drive wind turbine, the impedance value Z is... GSC and Z wf All are complex impedances, which have real and imaginary parts. The real part represents the resistive component, and the imaginary part represents the reactive component. They can also be represented by amplitude and phase. Let Z be an example. wf =R+jX, then the amplitude is The phase is arccos( ),Depend on Figure 7 It can be seen that the swept frequency impedance of the direct-drive wind turbine is basically consistent with the theoretical impedance, which verifies the accuracy of the high-frequency impedance of the constructed direct-drive wind turbine and demonstrates the effectiveness and accuracy of the identification method.

[0092] Example 2:

[0093] Based on the same inventive concept as Embodiment 1, this embodiment provides a control parameter identification system for grid-connected converters of new energy units. The method described includes:

[0094] The modeling module is used to establish a high-frequency impedance theoretical model of the converter, which includes unknown quantities of the current inner loop parameters, based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit and the current inner loop control structure.

[0095] The parameter identification module is used to obtain the high-frequency impedance model of the new energy unit grid-connected system based on the converter high-frequency impedance theoretical model, and to determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter ;

[0096] The impedance test module is used to apply harmonic voltage disturbances at different frequencies, measure the harmonic current of the unit at different frequencies, and thus obtain impedance values ​​at three different frequencies.

[0097] The parameter identification module is used to input impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

[0098] Example 3:

[0099] Based on the same inventive concept as Embodiment 1, this embodiment provides a computer-readable storage medium, which includes a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute the aforementioned method for identifying control parameters of a grid-connected converter for a new energy unit.

[0100] Example 4:

[0101] Based on the same inventive concept as Embodiment 1, this embodiment provides a processor for running a program, wherein the program executes the control parameter identification method for a grid-connected converter of a new energy unit.

[0102] Those skilled in the art will recognize that the modules of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.

[0103] In the embodiments provided by this invention, it should be understood that the division of modules is only a logical functional division. In actual implementation, there may be other division methods, such as multiple modules can be combined into one module, one module can be split into multiple modules, or some features can be ignored.

[0104] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0105] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for identifying control parameters of a grid-connected converter for a new energy generating unit, characterized in that, Includes the following steps: Step S1: Based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit, and the current inner loop control structure, establish a high-frequency impedance theoretical model of the converter that includes unknown quantities of the current inner loop parameters. Step S2: Obtain the high-frequency impedance model of the new energy unit grid-connected system based on the high-frequency impedance theoretical model of the converter, and determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter ; Step S3: Establish an impedance test module, apply harmonic voltage disturbances at different frequencies, measure the harmonic current of the unit at different frequencies, and then obtain the impedance values ​​at three different frequencies. Step S4: Input the impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

2. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 1, characterized in that, Step S1, establishing a high-frequency impedance theoretical model for the converter that includes unknown parameters of the inner current loop, specifically includes the following steps: Step S11: Establish the main circuit structure model and control model of the grid-connected converter for the new energy unit; wherein, the main circuit structure of the grid-connected converter for the new energy unit includes a DC / AC converter, an LCL filter, and a transformer connected in sequence, with the transformer connected to the power grid; the control model includes a voltage and current acquisition module, a current inner loop module, and a PWM module; the voltage and current acquisition module is connected to the LCL filter and the current inner loop module respectively; the current inner loop module is connected to the PWM module; the PWM module is connected to the DC / AC converter; Step S12: The voltage and current acquisition module acquires the output current of the DC / AC converter and the voltage at the midpoint of the two inductors of the LCL filter; the inner current loop module obtains the modulation voltage of the PWM module based on the inner loop current reference value, the output current of the DC / AC converter, and the voltage at the midpoint of the two inductors of the LCL filter; the PWM module outputs a trigger pulse to the DC / AC converter based on the modulation voltage to control the output current of the DC / AC converter; the output current of the DC / AC converter is: ； in, This is the reference value for the inner loop current. This refers to the output current of the DC / AC converter. This is the voltage at the midpoint between the two inductors in the LCL filter; The filter inductor is located near the machine side of the LCL filter; To control the delay, among which For the control delay of the converter; Let be the transfer function of the PI controller in the current inner loop module, where This is the proportionality coefficient for the inner current loop. s represents the integral coefficient of the inner current loop; s is the Laplace operator; This is the impedance reference value for the DC / AC converter; Step S13, will I ref When the fundamental current reference value is used, the theoretical model of the high-frequency impedance of the DC / AC converter is as follows: 。 3. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 2, characterized in that, The high-frequency impedance model of the new energy unit grid connection system in step S2 is as follows: ； in, For the LCL filter capacitor, The filter inductor is located near the grid side of the LCL filter; This is the equivalent inductance of the transformer. This represents the transformer turns ratio; / / indicates parallel impedance connection.

4. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 1, characterized in that, The impedance test module in step S3 includes a voltage source unit and a current measurement unit. The voltage source unit is used to apply harmonic voltage disturbances at different frequencies, and the current measurement unit is used to measure the harmonic current of the unit at different frequencies.

5. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 1, characterized in that, Harmonic voltage disturbance in step S3 Represented as: ； in, The amplitude of the disturbance value injected into the Nth harmonic. The frequency at which the disturbance value is injected for the Nth harmonic, h is the total number of harmonics; t is the time variable; frequency impedance for: ； in, , Frequency Lower harmonic voltage component and harmonic current component.

6. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 5, characterized in that, frequency The frequency values ​​are for the 1000Hz~1500Hz high-frequency band.

7. The method for identifying control parameters of a grid-connected converter for a new energy unit according to claim 6, characterized in that, ,in This is the fundamental frequency.

8. A control parameter identification system for a grid-connected converter of a new energy unit, characterized in that, The method described in any one of claims 1 to 7 comprises: The modeling module is used to establish a high-frequency impedance theoretical model of the converter, which includes unknown quantities of the current inner loop parameters, based on the main circuit structure and electrical parameters of the grid-connected converter of the new energy unit and the current inner loop control structure. The parameter identification module is used to obtain the high-frequency impedance model of the new energy unit grid-connected system based on the high-frequency impedance theoretical model of the converter, and to determine the parameters to be identified; the parameters to be identified include the proportional coefficient of the converter current inner loop. Integral coefficient of the converter current inner loop and the control delay of the converter ; The impedance test module is used to apply harmonic voltage disturbances at different frequencies, measure the harmonic current of the unit at different frequencies, and thus obtain impedance values ​​at three different frequencies. The parameter identification module is used to input impedance values ​​at three different frequencies into the high-frequency impedance model of the new energy unit grid connection system, and solve the high-frequency impedance model of the new energy unit grid connection system to obtain the parameters to be identified.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute the control parameter identification method for a grid-connected converter of a new energy unit as described in any one of claims 1 to 7.

10. A processor, characterized in that, The processor is used to run a program, wherein the program executes a control parameter identification method for a grid-connected converter of a new energy unit as described in any one of claims 1 to 7.

Images