An inner loop controller parameter determination method, system, device and storage medium

Abstract

The application discloses an inner loop controller parameter determination method, system, device and storage medium, and belongs to the technical field of power electronic power systems. The method comprises the following steps: acquiring an open-loop transfer function of a current loop of a power grid; determining proportional-resonant controller parameters through the open-loop transfer function, wherein the proportional-resonant controller parameters are proportional gain and resonant gain; determining a root locus according to the open-loop transfer function, and determining the proportional gain according to the root locus; and determining the resonant gain according to the proportional gain and the proportional-resonant controller parameters. The LCL type filter used by the support type converter of the power grid can be quickly determined to obtain the inner loop controller parameters of the support type converter.

Description

Technical Field

[0001] This invention relates to the field of power electronic power system technology, and more specifically, to a method, system, device, and storage medium for determining inner loop controller parameters. Background Technology

[0002] The large-scale integration of new energy sources such as wind and solar power into the power system, along with the increasing penetration of distributed resources like electric vehicles and energy storage, profoundly impacts the construction of a "new power system dominated by new energy sources." Grid-supporting power converters (GSCs) are central and play a crucial role. GSCs are key interface devices connecting distributed generation sources (DGS) to the grid. They can operate independently of the grid to supply power to loads, i.e., "islanding" operation, or they can operate connected to the grid, i.e., "grid-connected" operation. When the grid experiences power shortages, they can provide rapid power support. Especially when the equivalent inertia of the grid decreases after large-scale integration of new energy sources, they can provide inertia and damping to suppress frequency fluctuations.

[0003] Based on the brief overview above, grid-supported converters are multifunctional, and their performance depends on the performance of the grid-supported converter controller. A grid-supported converter controller typically consists of an outer loop and an inner loop. The inner loop is usually a current loop, responsible for zero-steady-state-error current command tracking; the outer loop is usually a voltage loop or a power loop, primarily responsible for energy management and generating the current command for the inner loop. A good inner-loop current controller offers superior command tracking performance, system stability, high power requirements, and the ability to suppress grid disturbances.

[0004] Typically, an L-type or LCL filter is installed between the inverter and the power grid to suppress high-order harmonics introduced by PWM modulation of the switching transistors. The admittance of an LCL filter exhibits a -60dB / dec attenuation at high frequencies, thus offering better high-frequency harmonic suppression compared to an L-type filter. The design of the inner-loop current controller parameters varies significantly depending on the filter used. For L-type filters, the controller parameters can usually be obtained using simple formulas. However, this simplicity is no longer applicable to LCL filters. Summary of the Invention

[0005] To address the above problems, this invention proposes a method for determining inner-loop controller parameters, comprising:

[0006] Obtain the open-loop transfer function of the current loop of the power grid;

[0007] The parameters of the proportional resonant controller are determined by the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain.

[0008] The root locus is determined based on the open-loop transfer function, and the proportional gain is determined based on the root locus.

[0009] The resonant gain is determined based on the proportional gain and the proportional resonant controller parameters;

[0010] The proportional gain and the resonant gain are the inner loop controller parameters of the supported converter.

[0011] Optionally, the open-loop transfer function of the current loop of the power grid can be obtained, including:

[0012] For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid;

[0013] Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

[0014] Optionally, based on the system control diagram, the open-loop transfer function of the current loop in the continuous domain of the system is determined, including:

[0015] Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current;

[0016] The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

[0017] Optionally, the open-loop transfer function is:

[0018]

[0019] Where T(s) is the open-loop transfer function, G ci (s) is the current controller function, G d (s) is the delay function. For the delay function G d The transfer function from the output of (s) to the grid-connected current.

[0020] Optionally, the proportional resonant controller parameters are determined using the open-loop transfer function, including:

[0021] The phase margin is determined based on the open-loop transfer function.

[0022] The parameters of the proportional resonant controller are determined based on the phase margin.

[0023] Optionally, determining the phase margin based on the open-loop transfer function includes:

[0024] The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current.

[0025] Alternatively, the formula for phase margin is as follows:

[0026]

[0027] Where, jω cr = variable s, where s is the complex parameter in the Laplace transform, T(jω) cr ) is s=jω in T(s) cr The open-loop transfer function, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, G d (jω cr ) is G d (s) in s=jω cr The delay function, for s=jω cr At that time, the delay function G d (jω cr The transfer function from the output of the grid-connected current. ω is the imaginary unit. cr T is the cutoff frequency. s φ is the sampling frequency. m For phase margin, L1 is the inductance value of the inverter-side filter inductor of the converter; L2 is the inductance value of the grid-side filter inductor of the converter; C f Here is the capacitance value of the converter filter capacitor; ∠T(jω) cr ) is T(jω cr The phase angle of ), T(s) is the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the input under zero initial conditions, T(s) is a complex parameter, and s is a rational fractional function.

[0028] Optionally, the formula for determining the parameters of the proportional resonant controller is:

[0029]

[0030] Among them, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, The imaginary unit is ω0, where ω is the fundamental angular frequency of the power grid. c Taken as π rad / s, ω cr K is the cutoff frequency. i / K p For the proportional resonant controller parameters, K p For proportional gain, K i For resonant gain, ∠G ci (jω cr ) is G ci (jω cr The phase angle of ).

[0031] Optionally, determining the root locus based on the open-loop transfer function includes:

[0032] Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system;

[0033] The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

[0034] Optionally, determining the proportional gain based on the root locus includes:

[0035] The proportional gain is determined based on the ratio of the root locus to the proportional gain.

[0036] This invention also proposes an inner-loop controller parameter determination system, comprising:

[0037] Obtain the function unit to obtain the open-loop transfer function of the current loop of the power grid;

[0038] The first calculation unit determines the proportional resonant controller parameters through the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain;

[0039] The proportional gain determination unit determines the root locus based on the open-loop transfer function and determines the proportional gain based on the root locus.

[0040] The resonant gain determination unit determines the resonant gain based on the proportional gain and the proportional resonant controller parameters;

[0041] The proportional gain and the resonant gain are the inner loop controller parameters of the supported converter.

[0042] Optionally, the open-loop transfer function of the current loop of the power grid can be obtained, including:

[0043] For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid;

[0044] Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

[0045] Optionally, based on the system control diagram, the open-loop transfer function of the current loop in the continuous domain of the system is determined, including:

[0046] Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current;

[0047] The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

[0048] Optionally, the open-loop transfer function is:

[0049]

[0050] Where T(s) is the open-loop transfer function, G ci (s) is the current controller function, G d (s) is the delay function. For the delay function G d The transfer function from the output of (s) to the grid-connected current.

[0051] Optionally, the proportional resonant controller parameters are determined using the open-loop transfer function, including:

[0052] The phase margin is determined based on the open-loop transfer function.

[0053] The parameters of the proportional resonant controller are determined based on the phase margin.

[0054] Optionally, determining the phase margin based on the open-loop transfer function includes:

[0055] The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current.

[0056] Alternatively, the formula for phase margin is as follows:

[0057]

[0058] Where, jω cr = variable s, where s is the complex parameter in the Laplace transform, T(jω) cr ) is s=jω in T(s) cr The open-loop transfer function, G ci (jω cr ) is G ci (s) in s=jω crThe current controller function, G d (jω cr ) is G d (s) in s=jω cr The delay function, for s=jω cr At that time, the delay function G d (jω cr The transfer function from the output of the grid-connected current. ω is the imaginary unit. cr T is the cutoff frequency. s φ is the sampling frequency. m For phase margin, L1 is the inductance value of the inverter-side filter inductor of the converter; L2 is the inductance value of the grid-side filter inductor of the converter; C f Here is the capacitance value of the converter filter capacitor; ∠T(jω) cr ) is T(jω cr The phase angle of ), T(s) is the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the input under zero initial conditions, T(s) is a complex parameter, and s is a rational fractional function.

[0059] Optionally, the formula for determining the parameters of the proportional resonant controller is:

[0060]

[0061] Among them, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, The imaginary unit is ω0, where ω is the fundamental angular frequency of the power grid. c Taken as π rad / s, ω cr K is the cutoff frequency. i / K p For the proportional resonant controller parameters, K p For proportional gain, K i For resonant gain, ∠G ci (jω cr ) is G ci (jω cr The phase angle of ).

[0062] Optionally, determining the root locus based on the open-loop transfer function includes:

[0063] Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system;

[0064] The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

[0065] Optionally, determining the proportional gain based on the root locus includes:

[0066] The proportional gain is determined based on the ratio of the root locus to the proportional gain.

[0067] The present invention also proposes a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the steps of an inner loop controller parameter determination method.

[0068] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of an inner loop controller parameter determination method.

[0069] This invention addresses the LCL-type filter used in grid-supported converters. By establishing an open-loop transfer function, the proportional gain and resonant gain are determined, and the inner-loop controller parameters of the grid-supported converter are also determined using the open-loop transfer function. Attached Figure Description

[0070] Figure 1 This is a flowchart of the method of the present invention;

[0071] Figure 2 This is a system control diagram of the method of the present invention;

[0072] Figure 3 This is the system control block diagram in the discrete domain;

[0073] Figure 4 The root locus plot of the system as Kp changes;

[0074] Figure 5 This is a structural diagram of the system of the present invention. Detailed Implementation

[0075] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0076] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0077] This invention proposes a method for determining the parameters of an inner-loop controller, such as... Figure 1 As shown, it includes:

[0078] Obtain the open-loop transfer function of the current loop of the power grid;

[0079] The parameters of the proportional resonant controller are determined by the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain.

[0080] The root locus is determined based on the open-loop transfer function, and the proportional gain is determined based on the root locus.

[0081] The resonant gain is determined based on the proportional gain and the proportional resonant controller parameters;

[0082] The proportional gain and the resonant gain are the inner loop controller parameters of the supported converter.

[0083] This invention addresses the LCL-type filter used in grid-supported converters, determining the proportional gain and resonant gain, thus defining the inner-loop controller parameters of the supported converter.

[0084] Among these, obtaining the open-loop transfer function of the power grid's current loop includes:

[0085] For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid;

[0086] Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

[0087] The determination of the open-loop transfer function of the current loop in the continuous domain of the system, based on the system control diagram, includes:

[0088] Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current;

[0089] The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

[0090] The open-loop transfer function is:

[0091]

[0092] Where T(s) is the open-loop transfer function, G ci (s) is the current controller function, G d (s) is the delay function. For the delay function G d The transfer function from the output of (s) to the grid-connected current.

[0093] The determination of the proportional resonant controller parameters through the open-loop transfer function includes:

[0094] The phase margin is determined based on the open-loop transfer function.

[0095] The parameters of the proportional resonant controller are determined based on the phase margin.

[0096] Determining the phase margin based on the open-loop transfer function includes:

[0097] The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current.

[0098] Alternatively, the formula for phase margin is as follows:

[0099]

[0100] Where, jω cr = variable s, where s is the complex parameter in the Laplace transform, T(jω) cr ) is s=jω in T(s) cr The open-loop transfer function, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, G d (jω cr ) is G d (s) in s=jω cr The delay function, for s=jω cr At that time, the delay function G d (jω cr The transfer function from the output of the grid-connected current. ω is the imaginary unit. cr T is the cutoff frequency. s φ is the sampling frequency. m For phase margin, L1 is the inductance value of the inverter-side filter inductor of the converter; L2 is the inductance value of the grid-side filter inductor of the converter; C fHere is the capacitance value of the converter filter capacitor; ∠T(jω) cr ) is T(jω cr The phase angle of ), T(s) is the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the input under zero initial conditions, T(s) is a complex parameter, and s is a rational fractional function.

[0101] The formula for determining the parameters of the proportional resonant controller is as follows:

[0102]

[0103] Among them, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, The imaginary unit is ω0, where ω is the fundamental angular frequency of the power grid. c Taken as π rad / s, ω cr K is the cutoff frequency. i / K p For the proportional resonant controller parameters, K p For proportional gain, K i For resonant gain, ∠G ci (jω cr ) is G ci (jω cr The phase angle of ).

[0104] Determining the root locus based on the open-loop transfer function includes:

[0105] Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system;

[0106] The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

[0107] Determining the proportional gain based on the root locus includes:

[0108] The proportional gain is determined based on the ratio of the root locus to the proportional gain.

[0109] The method of the present invention is specifically as follows:

[0110] Draw the system control diagram of the current control system in a power grid using a supported converter with an LCL filter. The system control diagram is as follows: Figure 2 As shown. Wherein, G ci (s) is a current controller, G d (s) is the delay function, Y L1 (s) is the admittance of the inverter-side filter inductor L1, ZC (s) represents the impedance of the filter capacitor C, Y L2 (s) is the admittance of the grid-side filter inductor L2, and its value is:

[0111]

[0112] i * i1(s) and i1(s) are the inverter output current command value and reference value, respectively, i2(s) is the grid-connected current, and v g It is the grid voltage;

[0113] r1 is the equivalent series resistance of the inverter-side filter inductor L1; r2 and L2 are the equivalent series resistances of the grid-side filter inductor L2.

[0114] The open-loop transfer function is:

[0115]

[0116] Where T(s) is the open-loop transfer function, G ci (s) is the current controller function, G d (s) is the delay function. For the delay function G d The transfer function from the output of (s) to the grid-connected current.

[0117] The open-loop transfer function is used to determine the phase margin, and determining the phase margin based on the open-loop transfer function includes:

[0118] The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current.

[0119] The formula for determining the phase margin is as follows:

[0120]

[0121] Where, jω cr =s,T(jω) cr ) is s=jω in T(s) cr The open-loop transfer function, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, G d (jω cr ) is G d (s) in s=jω cr The delay function, for s=jω crAt that time, the delay function G d (jω cr The transfer function from the output of the grid-connected current. ω is the imaginary unit. cr T is the cutoff frequency. s φ is the sampling frequency. m For phase margin, L1 is the inductance value of the inverter-side filter inductor of the converter; L2 is the inductance value of the grid-side filter inductor of the converter; C f This is the capacitance value of the converter filter capacitor.

[0122] The parameters of the proportional resonant controller are determined based on the proportional gain, resonant gain, cutoff frequency, etc., and the formula for determining the proportional resonant controller parameters is as follows:

[0123]

[0124] Among them, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, The imaginary unit is ω0, where ω is the fundamental angular frequency of the power grid. c Taken as π rad / s, ω cr K is the cutoff frequency. i / K p For the proportional resonant controller parameters, K p For proportional gain, K i This is the resonant gain.

[0125] Determining the system root locus includes:

[0126] Discretize the open-loop transfer function T(s) into T(z); the control block diagram of the system in the discrete z-domain is as follows. Figure 3 As shown. z-1 represents the computation delay. G ci (z), Y 2 vc (z) represent G ci (s), Y 2 vc Discretized form of (s).

[0127] The closed-loop poles of the current control system are determined based on T(z), and the root locus of the system is determined based on the closed-loop poles.

[0128] Specifically, the open-loop transfer function is discretized to obtain the pulse transfer function T(z) of the discrete system;

[0129] The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

[0130] Kp is determined based on the system root locus, and Ki is then determined by Ki / Kp;

[0131] Specifically, the closed-loop poles of the current control system can be obtained by 1 + T(z) = 0 (T(z) is the discretized form of T(s)). Here, the root locus method is used to analyze the impact of parameter changes on current control and system stability. The root locus of the system when Kp changes is as follows: Figure 4 As shown. This invention also proposes an inner-loop controller parameter determination system 200, as follows: Figure 5 As shown, it includes:

[0132] Get function unit 201 to get the open-loop transfer function of the current loop of the power grid;

[0133] The first calculation unit 202 determines the proportional resonant controller parameters through the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain.

[0134] The proportional gain determination unit 203 determines the root locus based on the open-loop transfer function and determines the proportional gain based on the root locus.

[0135] The resonant gain determination unit 204 determines the resonant gain based on the proportional gain and the proportional resonant controller parameters;

[0136] The proportional gain and the resonant gain are the inner loop controller parameters of the supported converter.

[0137] Among these, obtaining the open-loop transfer function of the power grid's current loop includes:

[0138] For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid;

[0139] Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

[0140] The determination of the open-loop transfer function of the current loop in the continuous domain of the system, based on the system control diagram, includes:

[0141] Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current;

[0142] The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

[0143] The open-loop transfer function is:

[0144]

[0145] Where T(s) is the open-loop transfer function, G ci (s) is the current controller function, G d (s) is the delay function. For the delay function G d The transfer function from the output of (s) to the grid-connected current.

[0146] The determination of the proportional resonant controller parameters through the open-loop transfer function includes:

[0147] The phase margin is determined based on the open-loop transfer function.

[0148] The parameters of the proportional resonant controller are determined based on the phase margin.

[0149] Determining the phase margin based on the open-loop transfer function includes:

[0150] The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current.

[0151] The formula for phase margin is as follows:

[0152]

[0153] Where, jω cr = variable s, where s is the complex parameter in the Laplace transform, T(jω) cr ) is s=jω in T(s) cr The open-loop transfer function, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, G d (jω cr ) is G d (s) in s=jω cr The delay function, for s=jω cr At that time, the delay function G d (jω cr The transfer function from the output of the grid-connected current. ω is the imaginary unit. cr T is the cutoff frequency. s φ is the sampling frequency. m For phase margin, L1 is the inductance value of the inverter-side filter inductor of the converter; L2 is the inductance value of the grid-side filter inductor of the converter; C f Here is the capacitance value of the converter filter capacitor; ∠T(jω)cr ) is T(jω cr The phase angle of ), T(s) is the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the input under zero initial conditions, T(s) is a complex parameter, and s is a rational fractional function.

[0154] The formula for determining the parameters of the proportional resonant controller is as follows:

[0155]

[0156] Among them, G ci (jω cr ) is G ci (s) in s=jω cr The current controller function, The imaginary unit is ω0, where ω is the fundamental angular frequency of the power grid. c Taken as π rad / s, ω cr K is the cutoff frequency. i / K p For the proportional resonant controller parameters, K p For proportional gain, K i For resonant gain, ∠G ci (jω cr ) is G ci (jω cr The phase angle of ).

[0157] Determining the root locus based on the open-loop transfer function includes:

[0158] Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system;

[0159] The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

[0160] Determining the proportional gain based on the root locus includes:

[0161] The proportional gain is determined based on the ratio of the root locus to the proportional gain.

[0162] The present invention also proposes a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the steps of an inner loop controller parameter determination method.

[0163] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of an inner loop controller parameter determination method.

[0164] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this 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. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0165] 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 this 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, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0166] 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 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0167] 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 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0168] Although preferred embodiments of this application 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 this application.

[0169] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for determining inner-loop controller parameters, the method comprising: Obtain the open-loop transfer function of the current loop of the power grid; The parameters of the proportional resonant controller are determined by the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain. The root locus is determined based on the open-loop transfer function, and the proportional gain is determined based on the root locus. The resonant gain is determined based on the proportional gain and the proportional resonant controller parameters; Wherein, the proportional gain and the resonant gain are the inner loop controller parameters of the supported converter; The open-loop transfer function is: ； in, T ( s Let be the open-loop transfer function. G ci ( s ) is the current controller function. G d ( s ) is a delay function. Delay function G d ( s The transfer function from the output of the grid-connected current; Determining the proportional resonant controller parameters using the open-loop transfer function includes: The phase margin is determined based on the open-loop transfer function. The parameters of the proportional resonant controller are determined based on the phase margin. The step of determining the phase margin based on the open-loop transfer function includes: The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current. The formula for determining the phase margin is as follows: Where, j ω cr =variable s, where s is a complex parameter in the Laplace transform. T (j ω cr )for T ( s In the case of s=j ω cr The open-loop transfer function, G ci (j ω cr )for G ci ( s In the case of s=j ω cr The current controller function, G d (j ω cr )for G d ( s In the case of s=j ω cr The delay function, (j) ω cr )for s = j ω cr Delay function G d (j ω cr The transfer function from the output of ) to the grid-connected current, j= The imaginary unit, ω cr The cutoff frequency, T s Sampling frequency, For phase margin, L 1 represents the inductance value of the inverter-side filter inductor of the converter; L 2 represents the inductance value of the grid-side filter inductor of the converter; C f This refers to the capacitance value of the converter filter capacitor; for T (j ω cr The phase angle of ) T(s) Let be the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the system input under zero initial conditions. T(s) It is a rational fractional function of s with complex parameters; The formula for determining the parameters of the proportional resonant controller is as follows: in, G ci (j ω cr )for G ci ( s In the case of s=j ω cr The current controller function, j= The imaginary unit, ω 0 represents the fundamental angular frequency of the power grid. ω c Taken as π rad / s, ω cr The cutoff frequency, K i / K p For the parameters of the proportional resonant controller, K p For proportional gain, K i For resonant gain, for G ci (j ω cr The phase angle of ).

2. The method according to claim 1, wherein obtaining the open-loop transfer function of the power grid current loop comprises: For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid; Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

3. The method according to claim 2, wherein determining the open-loop transfer function of the current loop in the continuous domain of the system based on the system control diagram comprises: Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current; The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

4. The method according to claim 2, wherein determining the root locus based on the open-loop transfer function comprises: Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system; The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

5. The method according to claim 1, wherein determining the proportional gain based on the root locus comprises: The proportional gain is determined based on the ratio of the root locus to the proportional gain.

6. An inner-loop controller parameter determination system, the system comprising: Obtain the function unit to obtain the open-loop transfer function of the current loop of the power grid; The first calculation unit determines the proportional resonant controller parameters through the open-loop transfer function, wherein the proportional resonant controller parameters are the ratio of the proportional gain to the resonant gain; The proportional gain determination unit determines the root locus based on the open-loop transfer function and determines the proportional gain based on the root locus. The resonant gain determination unit determines the resonant gain based on the proportional gain and the proportional resonant controller parameters; Wherein, the proportional gain and the resonant gain are the inner loop controller parameters of the supported converter; The open-loop transfer function is: ； in, T ( s Let be the open-loop transfer function. G ci ( s ) is the current controller function. G d ( s ) is a delay function. Delay function G d ( s The transfer function from the output of the grid-connected current; Determining the proportional resonant controller parameters using the open-loop transfer function includes: The phase margin is determined based on the open-loop transfer function. The parameters of the proportional resonant controller are determined based on the phase margin. The step of determining the phase margin based on the open-loop transfer function includes: The phase margin is determined based on the phase angle of the open-loop transfer function, the phase angle of the current controller function, the phase angle of the delay function, and the phase angle of the transfer function from the output of the delay function to the grid-connected current. The formula for determining the phase margin is as follows: Where, j ω cr =variable s, where s is a complex parameter in the Laplace transform. T (j ω cr )for T ( s In the case of s=j ω cr The open-loop transfer function, G ci (j ω cr )for G ci ( s In the case of s=j ω cr The current controller function, G d (j ω cr )for G d ( s In the case of s=j ω cr The delay function, (j) ω cr )for s = j ω cr Delay function G d (j ω cr The transfer function from the output of ) to the grid-connected current, j= The imaginary unit, ω cr The cutoff frequency, T s Sampling frequency, For phase margin, L 1 represents the inductance value of the inverter-side filter inductor of the converter; L 2 represents the inductance value of the grid-side filter inductor of the converter; C f This refers to the capacitance value of the converter filter capacitor; for T (j ω cr The phase angle of ) T(s) Let be the system transfer function, defined as the ratio of the Laplace transform of the system output to the Laplace transform of the system input under zero initial conditions. T(s) It is a rational fractional function of s with complex parameters; The formula for determining the parameters of the proportional resonant controller is as follows: in, G ci (j ω cr )for G ci ( s In the case of s=j ω cr The current controller function, j= The imaginary unit, ω 0 represents the fundamental angular frequency of the power grid. ω c Taken as π rad / s, ω cr The cutoff frequency, K i / K p For the parameters of the proportional resonant controller, K p For proportional gain, K i For resonant gain, for G ci (j ω cr The phase angle of ).

7. The system according to claim 6, wherein obtaining the open-loop transfer function of the power grid current loop comprises: For a supported converter using filters in a power grid, determine the system control diagram of the current control system in the power grid; Based on the system control diagram, determine the open-loop transfer function of the current loop in the continuous domain of the system.

8. The system according to claim 7, wherein determining the open-loop transfer function of the current loop in the continuous domain of the system based on the system control chart comprises: Based on the system control diagram, determine the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current; The open-loop transfer function is determined based on the current controller function, the delay function, and the transfer function from the output of the delay function to the grid-connected current.

9. The system according to claim 7, wherein determining the root locus based on the open-loop transfer function comprises: Discretizing the open-loop transfer function yields the pulse transfer function T(z) of the discrete system; The closed-loop poles of the current control system are determined based on T(z), and the root locus is determined based on the closed-loop poles.

10. The system according to claim 6, wherein determining the proportional gain based on the root locus comprises: The proportional gain is determined based on the ratio of the root locus to the proportional gain.

11. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

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