Method, device, equipment and medium for determining voltage chaos characteristics of network-forming inverter

Abstract

The invention provides a method, a device, equipment and a medium for determining voltage chaos characteristics of a network-forming inverter. The method comprises the following steps of: constructing a fractional order state equation comprising a switching function based on a circuit of the network-forming inverter; based on a fractional order generalized state space averaging method, converting the fractional order state equation into a fractional order generalized state space averaging equation, and based on the fractional order generalized state space averaging equation, constructing a fractional order generalized state space averaging model of the grid-forming inverter; and establishing a closed-loop system based on the fractional order generalized state space average model, calculating a time domain expression of the output voltage of the grid-forming inverter based on the closed-loop system, and determining the voltage chaos characteristics of the grid-forming inverter based on the time domain expression. According to the technical scheme provided by the embodiment of the invention, modeling can be carried out on the network-forming inverter to determine the voltage chaos characteristic of the network-forming inverter according to the fractional order characteristic caused by switching nonlinearity and the harmonic component of the output voltage and the output current in the circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-type inverters, and in particular to a method, device, equipment and medium for determining voltage chaos characteristics of a grid-type inverter. Background Art

[0002] The grid-type inverter is a controllable voltage source. However, under strong grid conditions, the coupling effect of the grid-type inverter is enhanced, and power oscillation is prone to occur, affecting the output of the grid-side current. Therefore, it is necessary to model the grid-type inverter and analyze the voltage chaos characteristics of the grid-type inverter based on the established model.

[0003] In the prior art, in the fractional time domain, the state space equation is used for modeling, and the fractional state space model and the fractional sequential model defined by GL (Grünwald-Letnikov) are used to predict FOSMPC, thereby realizing the discretization processing and numerical calculation of the fractional system. While considering the fractional-order characteristics of capacitors and inductors, the prior art uses the GL definition and Kirchhoff's law to construct the fractional-order state space equation of the circuit, and then discretizes it to obtain the corresponding discrete model. However, the existing modeling method in the fractional time domain is to average the multiple states caused by the switch of the grid-type inverter into one state, which cannot accurately represent the output voltage and output current characteristics in the grid-type inverter, and is not suitable for determining the chaotic characteristics of the output voltage in the grid-type inverter. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method, device, equipment, and medium for determining voltage chaos characteristics of a grid-type inverter, which can model the grid-type inverter and determine the voltage chaos characteristics of the grid-type inverter based on the fractional-order characteristics caused by the nonlinearity of the switch and the harmonic components of the output voltage and output current in the circuit.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining voltage chaos characteristics of a mesh inverter, wherein the conduction angle of each bridge arm of the mesh inverter is 180 degrees, the upper and lower arms of the same phase conduct alternately, and the conduction angles of each phase differ by 120 degrees, and the method comprises: Constructing a fractional-order state equation based on the circuit of the grid-building inverter, wherein the fractional-order state equation includes a switching function; Based on the fractional-order generalized state space averaging method, the fractional-order state equation is converted into a fractional-order generalized state space average equation, and a fractional-order generalized state space average model of the grid-connected inverter is constructed based on the fractional-order generalized state space average equation; A closed-loop system is established based on the fractional-order generalized state-space average model, a time-domain expression of the output voltage of the grid-type inverter is calculated based on the closed-loop system, and a voltage chaos characteristic of the grid-type inverter is determined based on the time-domain expression.

[0006] According to some embodiments of the present invention, the load of the grid-type inverter is a three-phase symmetrical resistance load connected in a triangle, the grid-type inverter includes a phase, a phase, and a phase. The fractional-order state equation is: , is the fractional order, t is the time, is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the output voltage of the c-phase and the a-phase, R is the load of the grid-type inverter, L Filter inductor, C Filter capacitors, is the equivalent series resistance of the inductor, is the conduction state of phase a, is the conduction state of phase b, is the conduction state of phase c, is the input voltage.

[0007] According to some embodiments of the present invention, the switch function , , a is the a phase, b is the b phase, c is the c phase, is the switching state of phase a of the grid-connected inverter, is the switching state of phase b of the grid-connected inverter, is the switching state of the c-phase of the grid-connected inverter.

[0008] According to some embodiments of the present invention, the fractional-order generalized state-space average equation is ,in, is the fractional order, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, is the equivalent series resistance of the inductor, L Filter inductor, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the output voltage of the a-phase and the b-phase, is the output voltage of the a-phase and the b-phase, is the output voltage of the a phase and the b phase, m is the amplitude modulation ratio, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the input voltage, is the fundamental angular frequency, t is the time, is the phase of the a phase, is the phase of the b-phase, is the phase of the c phase, j is an imaginary unit, is the angular frequency, for The first coefficient term of for The first coefficient term of for The first coefficient term of are the state variables of the a phase and the b phase, are the state variables of the a phase and the b phase, are the state variables of the phase a and the phase b, C is the filter capacitor, R is the load, for The zeroth coefficient term of for The zeroth coefficient term, for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth-order coefficient of .

[0009] According to some embodiments of the present invention, the fractional-order generalized state-space average model is ; for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, are the state variables of the a phase and the b phase, are the state variables of the a phase and the b phase, are the state variables of the c-phase and the a-phase, A is the real part of the coefficient term, I is the imaginary part of the coefficient term, is the equivalent series resistance of the inductor, L Filter inductor, is the fundamental angular frequency, C is the filter capacitor, R is the load, m is the amplitude modulation ratio, is the phase of the a phase, is the phase of the b-phase, is the phase of the c-phase, is the input voltage.

[0010] According to some embodiments of the present invention, after converting the fractional-order state equation into the fractional-order generalized state space average equation, the method further includes: Based on the fractional-order generalized state-space average model, the intermediate formula group is substituted to obtain the small signal model, where the intermediate formula group is , for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, are the state variables of the a phase and the b phase, are the state variables of the a phase and the b phase, are the state variables of the c-phase and the a-phase, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of are the output currents of the phase a and the phase b, is the output current of the b-phase and the c-phase, is the output current of the c-phase and the a-phase; Based on the small signal model, we can obtain Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, The transfer function and Transfer function of the amplitude modulation ratio.

[0011] According to some embodiments of the present invention, a closed-loop system is constructed based on a fractional-order generalized state space average model, and voltage chaos characteristics of the grid-connected inverter are analyzed based on the closed-loop system, including: Controlling the fractional-order generalized state space average model through a PI controller to establish a control model of the closed-loop system; By means of the control model and the fractional-order generalized state-space average model, a transfer function of the real part of the output voltage of the closed-loop system with respect to the modulation ratio and a transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the modulation ratio are obtained; A transfer function of the modulation ratio with respect to a reference voltage is obtained through the control model, and a transfer function of the real part of the output voltage of the closed-loop system, a transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the modulation ratio, and a transfer function of the modulation ratio with respect to the reference voltage are obtained. Performing inverse Laplace transform on the transfer function of the real part of the output voltage with respect to the reference voltage and the transfer function of the imaginary part of the output voltage with respect to the reference voltage, respectively, to obtain a time domain expression of the real part of the output voltage and a time domain expression of the imaginary part of the output voltage; Substitute the time domain expression of the real part of the output voltage and the time domain expression of the imaginary part of the output voltage into , obtain the time domain expression of the output voltage, and determine the voltage chaos characteristics of the grid-connected inverter based on the time domain expression of the output voltage, wherein, For signal, is the fundamental wave of the signal, The real part of the kth harmonic coefficient of the signal, represents the imaginary part of the kth harmonic coefficient of the signal, is the fundamental angular frequency.

[0012] In a second aspect, an embodiment of the present invention provides a device for determining the chaotic characteristics of the voltage of a grid-type inverter, comprising at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions that can be executed by the at least one control processor, and the instructions are executed by the at least one control processor so that the at least one control processor can execute the method for determining the chaotic characteristics of the voltage of a grid-type inverter as described in the first aspect above.

[0013] In a third aspect, an embodiment of the present invention provides an electronic device, comprising the device for determining voltage chaos characteristics of a grid-type inverter as described in the second aspect above.

[0014] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are used to execute the method for determining voltage chaos characteristics of a grid-type inverter as described in the first aspect above.

[0015] According to the method for determining the voltage chaos characteristics of a grid-type inverter according to an embodiment of the present invention, there are at least the following beneficial effects: constructing a fractional-order state equation based on the circuit of the grid-type inverter, wherein the fractional-order state equation includes a switching function; based on the fractional-order generalized state space averaging method, converting the fractional-order state equation into a fractional-order generalized state space average equation, and constructing a fractional-order generalized state space average model of the grid-type inverter based on the fractional-order generalized state space average equation; establishing a closed-loop system based on the fractional-order generalized state space average model, calculating the time domain expression of the output voltage of the grid-type inverter based on the closed-loop system, and determining the voltage chaos characteristics of the grid-type inverter based on the time domain expression. According to the technical solution of the embodiment of the present invention, the grid-type inverter can be modeled to determine the voltage chaos characteristics of the grid-type inverter according to the fractional-order characteristics caused by the nonlinearity of the switch and the harmonic components of the output voltage and output current in the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for determining voltage chaos characteristics of a grid-type inverter provided by an embodiment of the present invention; Figure 2 is a schematic diagram of a grid-connected inverter provided by another embodiment of the present invention; Figure 3 is a control block diagram of a control model of a closed-loop system provided by another embodiment of the present invention; Figure 4 It is a structural diagram of a device for determining voltage chaos characteristics of a grid-type inverter provided by another embodiment of the present invention. DETAILED DESCRIPTION

[0017] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0018] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0020] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0021] According to the method for determining the voltage chaos characteristics of a grid-type inverter according to an embodiment of the present invention, there are at least the following beneficial effects: constructing a fractional-order state equation based on the circuit of the grid-type inverter, wherein the fractional-order state equation includes a switching function; based on the fractional-order generalized state space averaging method, converting the fractional-order state equation into a fractional-order generalized state space average equation, and constructing a fractional-order generalized state space average model of the grid-type inverter based on the fractional-order generalized state space average equation; establishing a closed-loop system based on the fractional-order generalized state space average model, calculating the time domain expression of the output voltage of the grid-type inverter based on the closed-loop system, and determining the voltage chaos characteristics of the grid-type inverter based on the time domain expression. According to the technical solution of the embodiment of the present invention, the grid-type inverter can be modeled to determine the voltage chaos characteristics of the grid-type inverter according to the fractional-order characteristics caused by the nonlinearity of the switch and the harmonic components of the output voltage and output current in the circuit.

[0022] The control method of the embodiment of the present invention is further described below in conjunction with the accompanying drawings.

[0023] First, refer to Figure 1 and Figure 2 , Figure 1 The flowchart of the method for determining the voltage chaos characteristics of the grid-type inverter is shown in Figure 1. Figure 2 The schematic diagram of a grid-type inverter is shown in FIG. 1 . An embodiment of the present invention provides a method for determining voltage chaos characteristics of a grid-type inverter. The conduction angle of each bridge arm of the grid-type inverter is 180 degrees. The upper and lower arms of the same phase conduct electricity alternately. The conduction angles of each phase differ by 120 degrees. The method includes but is not limited to the following steps: S10, constructing a fractional-order state equation based on a circuit of the grid-forming inverter, wherein the fractional-order state equation includes a switching function; S20, based on the fractional-order generalized state space averaging method, the fractional-order state equation is converted into a fractional-order generalized state space average equation, and a fractional-order generalized state space average model of the grid-connected inverter is constructed based on the fractional-order generalized state space average equation; S30, establishing a closed-loop system based on a fractional-order generalized state-space average model, calculating a time-domain expression of an output voltage of the grid-forming inverter based on the closed-loop system, and determining voltage chaos characteristics of the grid-forming inverter based on the time-domain expression.

[0024] It should be noted that, refer to Figure 2 Since the basic working mode of the grid-type inverter is the 180-degree conduction mode, the conduction angle of each bridge arm of the grid-type inverter is 180 degrees. The upper bridge arm and the lower bridge arm of the same phase conduct alternately, and the conduction angles of each phase of the grid-type inverter differ by 120 degrees. That is, at any moment, three bridge arms will be turned on at the same time. The conduction situation may be the upper bridge arm and the lower two bridge arms, or the upper two bridge arms and the lower bridge arm may be turned on at the same time.

[0025] It should be noted that when the load of the grid-type inverter is a three-phase symmetrical resistance load connected in a triangle, the grid-type inverter includes phase a, phase b and phase c. For the output of phase a, when the bridge arm ap is turned on, , when the bridge arm an is turned on, .therefore, The waveform has an amplitude of The rectangular wave of phase b and phase c can be obtained in the same way, where the bridge arm ap is the upper bridge arm of phase a of the grid-type inverter, and the bridge arm an is the lower bridge arm of phase a of the grid-type inverter. is the phase current of phase a, is the input voltage.

[0026] It should be noted that each bridge arm of the grid-type inverter is provided with a switch tube. In this application, the switch function Indicates the conduction state of the switch tube of each phase in the grid-type inverter. , , where a is phase a, b is phase b, c is phase c, p is the upper switch tube of each item, and n is the lower switch tube of each phase. The upper and lower tubes of each phase are turned on in turn. In addition, according to the principle of grid-type inverter, .

[0027] It should be noted that in S10, in this embodiment, the load of the grid-type inverter is a three-phase symmetrical resistance load connected in a triangle, and the load is R. Based on the principle of the grid-type inverter, it is obtained (1) (2) in, is the fractional order, t is the time, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the phase voltage of phase a, is the phase voltage of phase b, is the phase voltage of phase c, L is the filter inductance, is the phase current of phase a, is the phase current of phase b, is the phase current of phase c, is the equivalent series resistance of the inductor, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the output voltage of the c-phase and the a-phase, is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, and C is the filter capacitor; And there are (3) Reference Figure 2 According to the principle of grid-connected inverter, we can get (4) in, is the conduction state of phase a, is the conduction state of phase b, is the conduction state of phase c, is the input voltage; Combining formula (1) to formula (4), the fractional-order state equation of the grid-connected inverter is obtained: (5) in, , , , , , is a state variable.

[0028] It should be noted that the fractional-order generalized state-space averaging method represents an independent power system as a differential equation system with Fourier series as state variables, and uses time-varying Fourier series expansion to approximate all system state variables including nonlinear state variables. The basic formula of the generalized state-space averaging method used in this scheme needs to be given.

[0029] It should be noted that the fractional-order generalized state-space averaging method uses Fourier expansion to approximate the state variables in the power system. If the state variables If the Fourier transform condition is satisfied, then the state variable In a cycle The exponential expansion of the Fourier series in can be expressed as (6) in , is the fundamental angular frequency, and the switching frequency is ,plural is the k-th coefficient in the Fourier series, so there is the k-th coefficient formula of the Fourier series: (7) Its differential form can be obtained through formula (7): (8) The important property of Fourier transform used in the fractional-order generalized state-space averaging method is the frequency domain convolution theorem of Fourier transform, that is, if a signal is the product of two variables x and y, where x and y are functions of time t and the Fourier transform of x and y exists, then the signal The Fourier transform of (9) For example The 0th coefficient term is (10) The first coefficient term is (11) The kth coefficient term is

[0030] Among them, A is the real part of the coefficient term, I is the imaginary part of the coefficient term, ; Based on the fractional-order generalized state space averaging method and the working principle of the grid-connected inverter, the switching function Expressed as

[0031] (13) in =a,b,c, is the conduction state of phase a, is the conduction state of phase b, is the conduction state of phase c, is the fundamental angular frequency, , , , is the initial phase, m is the amplitude modulation ratio; Combining formula (13) and formula (5), we can get (14) Formula (14) is transformed into the fractional-order generalized state space average equation using formula (8): (15) In this embodiment, the input voltage is a DC quantity, so =0, = , and the output voltage and output current are both AC quantities, as state variables, the kth harmonic is mainly considered in the state space average equation; Using formula (6), we can get (16) Where i = a, b, c. Finally, substitute formula (6) to formula (12) and formula (16) into formula (15) to obtain the fractional-order generalized state space average model of the grid-connected inverter: (17).

[0032] In addition, in one embodiment, in S20, after converting the fractional-order state equation into the fractional-order generalized state space average equation, the following steps are also included but not limited to: S21, based on the fractional-order generalized state-space average model, substitute the intermediate formula group to obtain a small signal model, wherein the intermediate formula group is , for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the line current of phase a and phase b, is the line current of phase b and phase c, is the line current of phase c and phase a, are the state variables of phase a and phase b, are the state variables of phase a and phase b, are the state variables of phase c and phase a, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the output current of phase a and phase b, is the output current of phase b and phase c, is the output current of phase c and phase a; S22, based on the small signal model, are obtained Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, The transfer function and Transfer function of the amplitude modulation ratio.

[0033] It should be noted that Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, The transfer function and The transfer function of the amplitude modulation ratio can provide a basis for establishing a closed-loop system based on the fractional-order generalized state-space average model and analyzing the voltage chaos characteristics of the closed-loop system.

[0034] In addition, in one embodiment, referring to Figure 3 , Figure 3 The control block diagram of the control model of the closed-loop system includes, but is not limited to, the following steps in S30: S31, controlling the fractional-order generalized state space average model through a PI controller to establish a control model of the closed-loop system; S32, obtaining a transfer function of a real part of an output voltage of a closed-loop system with respect to a modulation ratio and a transfer function of an imaginary part of an output voltage of the closed-loop system with respect to a modulation ratio through a control model and a fractional-order generalized state-space average model; S33, obtaining a transfer function of the modulation ratio with respect to the reference voltage through the control model, and obtaining a transfer function of the real part of the output voltage of the closed-loop system with respect to the modulation ratio and a transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the reference voltage and a transfer function of the imaginary part of the output voltage with respect to the reference voltage based on the real part of the output voltage of the closed-loop system, the transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the modulation ratio and the transfer function of the modulation ratio with respect to the reference voltage; S34, performing inverse Laplace transform on the transfer function of the real part of the output voltage with respect to the reference voltage and the transfer function of the imaginary part of the output voltage with respect to the reference voltage, respectively, to obtain a time domain expression of the real part of the output voltage and a time domain expression of the imaginary part of the output voltage; S35, substituting the time domain expression of the real part of the output voltage and the time domain expression of the imaginary part of the output voltage into , obtain the time domain expression of the output voltage, and determine the voltage chaos characteristics of the grid-connected inverter based on the time domain expression of the output voltage, wherein, For signal, is the fundamental wave of the signal, The real part of the kth harmonic coefficient of the signal, represents the imaginary part of the kth harmonic coefficient of the signal, is the fundamental angular frequency.

[0035] It should be noted that the model applied for in this proposal takes into account the harmonic components of the output voltage and output current in the grid-connected inverter, so that the closed-loop system established based on the fractional-order generalized state-space average model can accurately represent the output voltage and output current characteristics.

[0036] like Figure 4 As shown, Figure 4 1 is a structural diagram of a device for determining chaotic characteristics of voltage of a grid-type inverter provided by an embodiment of the present invention. The present invention also provides a device for determining chaotic characteristics of voltage of a grid-type inverter, comprising: The processor 401 may be implemented by a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application; The memory 402 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 402 can store an operating system and other application programs. When the technical solution provided in the embodiment of this specification is implemented by software or firmware, the relevant program code is stored in the memory 402, and the processor 401 calls and executes the method for determining the voltage chaos characteristics of the grid-type inverter in the embodiment of this application; Input / output interface 403, used to implement information input and output; Communication interface 404, used to realize communication interaction between the device and other devices, which can be realized through wired mode (such as USB, network cable, etc.) or wireless mode (such as mobile network, WIFI, Bluetooth, etc.); A bus 405 that transmits information between various components of the device (e.g., processor 401, memory 402, input / output interface 403, and communication interface 404); The processor 401 , the memory 402 , the input / output interface 403 and the communication interface 404 are connected to each other in communication within the device via the bus 405 .

[0037] An embodiment of the present application also provides an electronic device, comprising the device for determining voltage chaos characteristics of a grid-type inverter as described above.

[0038] An embodiment of the present application further provides a storage medium, which is a computer-readable storage medium and stores a computer program. When the computer program is executed by a processor, the above-mentioned method for determining the voltage chaos characteristics of the grid-type inverter is implemented.

[0039] As a non-transient computer-readable storage medium, the memory can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and are implemented to be located in one place, or may also be distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0040] It will be appreciated by those skilled in the art that all or some of the steps and systems in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transient medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically include computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0041] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions under the shared conditions without violating the spirit of the present invention. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for determining voltage chaos characteristics of a grid-connected inverter, characterized in that: The conduction angle of each bridge arm of the grid-type inverter is 180 degrees, the upper and lower arms of the same phase conduct electricity alternately, and the conduction angles of each phase start to differ by 120 degrees. The method comprises: Constructing a fractional-order state equation based on the circuit of the grid-building inverter, wherein the fractional-order state equation includes a switching function; Based on the fractional-order generalized state space averaging method, the fractional-order state equation is converted into a fractional-order generalized state space average equation, and a fractional-order generalized state space average model of the grid-connected inverter is constructed based on the fractional-order generalized state space average equation; A closed-loop system is established based on the fractional-order generalized state-space average model, a time-domain expression of the output voltage of the grid-type inverter is calculated based on the closed-loop system, and a voltage chaos characteristic of the grid-type inverter is determined based on the time-domain expression.

2. The method for determining voltage chaos characteristics of a grid-connected inverter according to claim 1, characterized in that: The load of the grid-type inverter is a three-phase symmetrical resistance load connected in a triangle. The grid-type inverter includes phase a, phase b and phase c. The fractional-order state equation is: , is the fractional order, t is the time, is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the line voltage between the phase a and the phase b, is the output voltage of the c-phase and the a-phase, R is the load of the grid-type inverter, L Filter inductor, C Filter capacitors, is the equivalent series resistance of the inductor, is the conduction state of phase a, is the conduction state of phase b, is the conduction state of phase c, is the input voltage.

3. The method for determining voltage chaos characteristics of a grid-type inverter according to claim 2, characterized in that: The switch function , , a is the a phase, b is the b phase, c is the c phase, is the switching state of phase a of the grid-connected inverter, is the switching state of phase b of the grid-connected inverter, is the switching state of the c-phase of the grid-connected inverter.

4. The method for determining voltage chaos characteristics of a grid-connected inverter according to claim 1, characterized in that: The fractional-order generalized state-space average equation is ,in, is the fractional order, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, is the equivalent series resistance of the inductor, L Filter inductor, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the output voltage of the a-phase and the b-phase, is the output voltage of the a-phase and the b-phase, is the output voltage of the a phase and the b phase, m is the amplitude modulation ratio, for The first coefficient term of for The first coefficient term of for The first coefficient term of is the input voltage, is the fundamental angular frequency, t is the time, is the phase of the a phase, is the phase of the b-phase, is the phase of the c phase, j is an imaginary unit, is the angular frequency, for The first coefficient term of for The first coefficient term of for The first coefficient term of are the state variables of the a phase and the b phase, are the state variables of the a-phase and the b-phase, are the state variables of the phase a and the phase b, C is the filter capacitor, R is the load, for The zeroth coefficient term of for The zeroth coefficient term, for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth coefficient term of for The zeroth-order coefficient of .

5. The method for determining voltage chaos characteristics of a grid-connected inverter according to claim 2, characterized in that: The fractional-order generalized state-space average model is , for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, are the state variables of the a-phase and the b-phase, are the state variables of the a-phase and the b-phase, are the state variables of the c-phase and the a-phase, A is the real part of the coefficient term, I is the imaginary part of the coefficient term, is the equivalent series resistance of the inductor, L Filter inductor, is the fundamental angular frequency, C is the filter capacitor, R is the load, m is the amplitude modulation ratio, is the phase of the a phase, is the phase of the b-phase, is the phase of the c-phase, is the input voltage.

6. The method for determining voltage chaos characteristics of a grid-connected inverter according to claim 2, characterized in that: After converting the fractional-order state equation into the fractional-order generalized state space average equation, it also includes: Based on the fractional-order generalized state-space average model, the intermediate formula group is substituted to obtain the small signal model, where the intermediate formula group is , for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of is the line current of the phase a and the phase b, is the line current of the b-phase and the c-phase, is the line current of the c-phase and the a-phase, are the state variables of the a-phase and the b-phase, are the state variables of the a-phase and the b-phase, are the state variables of the c-phase and the a-phase, for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of for The real part of the first coefficient term of for The imaginary part of the first coefficient term of are the output currents of the phase a and the phase b, is the output current of the b-phase and the c-phase, is the output current of the c-phase and the a-phase; Based on the small signal model, we can obtain Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, Transfer function of the amplitude modulation ratio, The transfer function and Transfer function of the modulation ratio.

7. The method for determining voltage chaos characteristics of a grid-connected inverter according to claim 1, characterized in that: A closed-loop system is constructed based on a fractional-order generalized state space average model, and voltage chaos characteristics of the grid-connected inverter are analyzed based on the closed-loop system, including: Controlling the fractional-order generalized state space average model through a PI controller to establish a control model of the closed-loop system; By means of the control model and the fractional-order generalized state-space average model, a transfer function of the real part of the output voltage of the closed-loop system with respect to the modulation ratio and a transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the modulation ratio are obtained; A transfer function of the modulation ratio with respect to a reference voltage is obtained through the control model, and a transfer function of the real part of the output voltage of the closed-loop system, a transfer function of the imaginary part of the output voltage of the closed-loop system with respect to the modulation ratio, and a transfer function of the modulation ratio with respect to the reference voltage are obtained. Performing inverse Laplace transform on the transfer function of the real part of the output voltage with respect to the reference voltage and the transfer function of the imaginary part of the output voltage with respect to the reference voltage, respectively, to obtain a time domain expression of the real part of the output voltage and a time domain expression of the imaginary part of the output voltage; Substitute the time domain expression of the real part of the output voltage and the time domain expression of the imaginary part of the output voltage into , obtain the time domain expression of the output voltage, and determine the voltage chaos characteristics of the grid-connected inverter based on the time domain expression of the output voltage, wherein, For signal, is the fundamental wave of the signal, The real part of the kth harmonic coefficient of the signal, represents the imaginary part of the kth harmonic coefficient of the signal, is the fundamental angular frequency.

8. A device for determining voltage chaos characteristics of a grid-type inverter, characterized in that: It includes at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions that can be executed by the at least one control processor, and the instructions are executed by the at least one control processor so that the at least one control processor can execute the method for determining the voltage chaos characteristics of a grid-type inverter as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: It includes the device for determining voltage chaos characteristics of a grid-type inverter as described in claim 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the method for determining voltage chaos characteristics of a grid-type inverter according to any one of claims 1 to 7.

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