Oscillation suppression strategy and device for single-phase inverter based on second-order generalized integrator

Abstract

The present invention relates to a single-phase inverter oscillation suppression strategy and device based on a second-order generalized integrator, wherein the single-phase inverter is provided with a phase-locked loop based on the second-order generalized integrator, and the single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator. Compared with the prior art, the present invention only changes the bandwidth parameter of SOGI, that is, the parameter k of the second-order generalized integrator, to suppress the oscillation of the grid-connected inverter, without adjusting other parameters, which is convenient and reliable, and does not affect the control characteristics of the inverter.

Description

Technical Field

[0001] The invention relates to the field of single-phase inverter oscillation suppression, and in particular to a single-phase inverter oscillation suppression strategy and device based on a second-order generalized integrator. Background Art

[0002] In recent years, with the continuous increase in the capacity of renewable energy connected to the grid, power electronic equipment such as voltage source converter (VSC), as the connector between renewable energy power generation system and the power grid, interacts with weak power grids in the process of connecting renewable energy to the power grid, resulting in sub-supersynchronous oscillations and reducing the stability of the system.

[0003] In actual operation, the output impedance of the inverter is affected by the phase locked loop (PLL). In order to control the power generated by the grid-connected inverter, a phase locked loop is used to obtain the phase of the grid voltage and generate a synchronous current reference signal. The second order generalized integrator phase-locked loop (SOGI-PLL) is more common in single-phase systems due to its simple structure and high detection accuracy.

[0004] Existing research shows that the phase-locked loop has a significant impact on the grid-connected stability of the inverter, and this impact depends on factors such as load conditions, inverter power factor, and phase-locked loop parameters. For unstable phenomena such as sub- / super-synchronous oscillations that occur during the inverter grid connection process, existing measures include changing the phase-locked loop bandwidth, adjusting the current loop parameters, and reducing the inverter output power. However, these methods have modified the control structure and control objectives of the inverter, which will affect the control characteristics of the inverter. Summary of the invention

[0005] The purpose of the present invention is to provide a single-phase inverter oscillation suppression strategy and device based on a second-order generalized integrator in order to overcome the defects of the above-mentioned prior art that affect the control characteristics of the inverter.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A single-phase inverter oscillation suppression strategy based on a second-order generalized integrator, wherein the single-phase inverter is provided with a phase-locked loop based on the second-order generalized integrator. The single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator.

[0008] Furthermore, the transfer function of the second-order generalized integrator is expressed as:

[0009]

[0010]

[0011] Where s is the Laplace operator, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, ω1 is the fundamental frequency, and k is the second-order generalized integrator control parameter;

[0012] The single-phase inverter oscillation suppression strategy is specifically to suppress the oscillation of the single-phase inverter by reducing the parameter k of the second-order generalized integrator.

[0013] Furthermore, the single-phase inverter oscillation suppression strategy is specifically as follows: after the single-phase inverter is connected to the grid, the impedance of the single-phase inverter is calculated according to the single-phase inverter impedance model, so as to judge the stability of the single-phase inverter; if the single-phase inverter is in an unstable state, the oscillation of the single-phase inverter is suppressed by reducing the bandwidth of the second-order generalized integrator.

[0014] Further, the single-phase inverter is an LCL type single-phase inverter, the LCL type single-phase inverter includes an LCL filter, and the expression of the single-phase inverter impedance model is:

[0015]

[0016] T=G X1 G X2

[0017]

[0018]

[0019] Z L1 =sL1

[0020] Z L2 =sL2

[0021] Z c =1 / sC f +R d

[0022] In the formula, Z p is the impedance of the single-phase inverter, G SOGI-PLL is the transfer function of the phase-locked loop based on the second-order generalized integrator, s is the Laplace operator, L1 is the first inductor of the LCL filter, L2 is the second inductor of the LCL filter, C f is the capacitance of the LCL filter, R d is the resistance of the LCL filter, Im is the inverter output current amplitude, K PWM is the pulse width modulation coefficient, H i is the current loop transfer function.

[0023] Furthermore, the transfer function of the phase-locked loop based on the second-order generalized integrator is expressed as:

[0024]

[0025]

[0026]

[0027]

[0028] In the formula, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, U1 is the voltage amplitude at the fundamental frequency f1, ω1 is the fundamental frequency angular frequency and ω1=2πf1, k is the second-order generalized integrator control parameter, H PLL (s) is the open-loop transfer function of the phase-locked loop.

[0029] The present invention also provides a single-phase inverter oscillation suppression device based on a second-order generalized integrator, wherein the single-phase inverter is provided with a phase-locked loop based on the second-order generalized integrator, and the single-phase inverter oscillation suppression device comprises a memory and a processor, wherein the memory stores a computer program, and the processor calls the computer program to execute a single-phase inverter oscillation suppression strategy, wherein the single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator.

[0030] Furthermore, the transfer function of the second-order generalized integrator is expressed as:

[0031]

[0032]

[0033] Where s is the Laplace operator, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, ω1 is the fundamental frequency, and k is the second-order generalized integrator control parameter;

[0034] The single-phase inverter oscillation suppression strategy is specifically to suppress the oscillation of the single-phase inverter by reducing the parameter k of the second-order generalized integrator.

[0035] Furthermore, the single-phase inverter oscillation suppression strategy is specifically as follows: after the single-phase inverter is connected to the grid, the impedance of the single-phase inverter is calculated according to the single-phase inverter impedance model, so as to judge the stability of the single-phase inverter; if the single-phase inverter is in an unstable state, the oscillation of the single-phase inverter is suppressed by reducing the bandwidth of the second-order generalized integrator.

[0036] Furthermore, the expression of the single-phase inverter impedance model is:

[0037]

[0038]

[0039] Z L1 =sL1

[0040] Z L2 =sL2

[0041] Z c =1 / sC f +R d

[0042] In the formula, Z p is the impedance of the single-phase inverter, G SOGI-PLL is the transfer function of the phase-locked loop based on the second-order generalized integrator, s is the Laplace operator, L1 is the first inductor of the LCL filter, L2 is the second inductor of the LCL filter, C f is the capacitance of the LCL filter, R d is the resistance of the LCL filter, I m is the inverter output current amplitude, K PWM is the pulse width modulation coefficient, H i is the current loop transfer function.

[0043] Furthermore, the transfer function of the phase-locked loop based on the second-order generalized integrator is expressed as:

[0044]

[0045]

[0046]

[0047]

[0048] In the formula, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, U1 is the voltage amplitude at the fundamental frequency f1, ω1 is the fundamental frequency, k is the second-order generalized integrator control parameter, H PLL(s) is the open-loop transfer function of the phase-locked loop.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] (1) The quadrature signal generator (QSG) is implemented by a second-order generalized integrator, which improves the overall performance and accuracy of the single-phase phase-locked loop. Only by changing the bandwidth parameter of SOGI, that is, the parameter k of the second-order generalized integrator, the oscillation of the grid-connected inverter can be suppressed without adjusting other parameters. It is convenient and reliable. At the same time, the existing method achieves oscillation suppression by adjusting the current loop and phase-locked loop parameters. This process inevitably changes the original optimal control parameters. The present invention uses the orthogonal signal generator to apply the oscillation suppression strategy only in the signal extraction stage. The various parameters of the inverter internal control loop remain unchanged, so it does not affect the original control characteristics of the inverter, ensuring the original optimal control effect of the inverter.

[0051] (2) The combination of impedance analysis and SOGI bandwidth can easily realize the frequency characteristic modeling of the grid-connected inverter system and effectively simplify the complexity of the interactive system stability analysis;

[0052] (3) The harmonic linearization method is used to analyze the single-phase inverter. The fundamental component of the output signal of the nonlinear link is used to approximate the actual output under the action of the sinusoidal signal, which can well describe the nonlinear system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The structure diagram of the LCL type single-phase grid-connected inverter of the present invention;

[0054] Figure 2 It is a schematic diagram of the structure of SOGI-PLL of the present invention;

[0055] Figure 3 It is a schematic diagram of the SOGI control block diagram of the present invention;

[0056] Figure 4 H under different parameters k of the present invention α Bode plot of (s);

[0057] Figure 5 H under different parameters k of the present invention β Bode plot of (s);

[0058] Figure 6 This is a control block diagram of the grid-connected inverter of the present invention;

[0059] Figure 7 A simplified diagram of the grid-connected inverter control of the present invention;

[0060] Figure 8 It is the equivalent circuit diagram of the LCL type grid-connected inverter of the present invention;

[0061] Fig. 9 The theoretical results of the present invention and Z P2 The simulation results of

[0062] Fig.10 Z of the present invention P1 ,Z P2 and Z g Impedance curve;

[0063] Fig.11 This is the inverter oscillation state analysis diagram of the present invention, Fig.11 11(a) is the waveform of the oscillation of the inverter of the present invention, and 11(b) is the fast Fourier analysis of the oscillating current;

[0064] Fig.12 This is the steady-state analysis diagram of the inverter of the present invention. Fig.12 12(a) is the steady-state waveform of the inverter of the present invention, and 12(b) is the fast Fourier analysis of the steady-state current waveform;

[0065] Fig.13 It is a schematic diagram of the flow chart of the oscillation suppression strategy of the single-phase inverter of the present invention. DETAILED DESCRIPTION

[0066] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0067] Example 1

[0068] This embodiment provides a single-phase inverter oscillation suppression strategy based on a second-order generalized integrator. The single-phase inverter is provided with a phase-locked loop based on the second-order generalized integrator. The single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator.

[0069] The transfer function expression of the second-order generalized integrator is:

[0070]

[0071]

[0072] Where s is the Laplace operator, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, ω1 is the fundamental frequency, and k is the second-order generalized integrator control parameter.

[0073] Furthermore, the oscillation of the single-phase inverter is suppressed by reducing the parameter k of the second-order generalized integrator.

[0074] The single-phase inverter oscillation suppression strategy is introduced in detail below.

[0075] like Fig.13 As shown, the oscillation suppression strategy is specifically as follows: after the single-phase inverter is connected to the grid, the impedance of the single-phase inverter is calculated according to the single-phase inverter impedance model, so as to judge the stability of the single-phase inverter; if the single-phase inverter is in an unstable state, the oscillation of the single-phase inverter is suppressed by reducing the bandwidth of the second-order generalized integrator.

[0076] The expression of the single-phase inverter impedance model is:

[0077]

[0078]

[0079] Z L1 =sL1

[0080] Z L2 =sL2

[0081] Z c =1 / sC f +R d

[0082] In the formula, Z p is the impedance of the single-phase inverter, G SOGI-PLL is the transfer function of the phase-locked loop based on the second-order generalized integrator, s is the Laplace operator, L1 is the first inductor of the LCL filter, L2 is the second inductor of the LCL filter, C f is the capacitance of the LCL filter, R d is the resistance of the LCL filter, I m is the inverter output current amplitude, K PWM is the pulse width modulation coefficient, H i is the current loop transfer function.

[0083] The transfer function of the phase-locked loop based on the second-order generalized integrator is expressed as:

[0084]

[0085]

[0086]

[0087]

[0088] In the formula, H α (s) is the transfer function of the α-axis component, H β (s) is the β-axis component transfer function, U1 is the voltage amplitude at the fundamental frequency f1, ω1 is the fundamental frequency, k is the second-order generalized integrator control parameter, H PLL (s) is the open-loop transfer function of the phase-locked loop.

[0089] This embodiment also provides a single-phase inverter oscillation suppression device based on a second-order generalized integrator. The single-phase inverter oscillation suppression device includes a memory and a processor. The memory stores a computer program, and the processor calls the computer program to execute the above-mentioned single-phase inverter oscillation suppression strategy based on the second-order generalized integrator.

[0090] Specific implementation:

[0091] This embodiment proposes a VSC impedance model based on a second order generalized integrator phase-locked loop (SOGI-PLL), and compares the effects of different SOGI bandwidths on VSC impedance using the Nyquist stability criterion. First, the dynamic characteristics of SOGI-PLL are analyzed, and the inverter impedance model considering the SOGI bandwidth is established using the harmonic linearization method. The impedance analysis method is used to analyze the stability of VSCs with two different SOGI bandwidths under weak power grids. The results show that under the same control parameters, the VSC with a smaller SOGI bandwidth makes the system more stable.

[0092] The process of this embodiment includes the following points:

[0093] (1) Establish an LCL type single-phase grid-connected inverter model;

[0094] (2) Discuss the relationship between SOGI bandwidth and parameter k;

[0095] (3) Use the harmonic linearization method to derive the transfer function of SOGI-PLL;

[0096] (4) Design PI parameters in the PLL control loop;

[0097] (5) Calculate the inverter impedance and give the relationship between SOGI bandwidth and inverter impedance;

[0098] (6) Analyze system stability using Nyquist stability criterion;

[0099] (7) Use Simulink simulation to verify the inverter theoretical impedance;

[0100] (8) Compare the performance of inverters with different SOGI bandwidths.

[0101] A detailed description is given below.

[0102] Figure 1 The structure diagram of the LCL type single-phase grid-connected inverter in this embodiment is shown in FIG. f , R d and L2 form an LCL filter. The present invention uses SOGI-PLL to obtain the grid voltage phase. Among them, H i (s) is a proportional resonant (PR) current controller, and its transfer function is:

[0103]

[0104] In order to establish the VSC impedance model, a small disturbance is injected into the grid voltage. In the present invention, a voltage disturbance is injected into the AC side of the single-phase VSC:

[0105] u p =U p cos(2πf p t+θ up )

[0106] For simplicity, we assume that the power grid is ideal.

[0107] u PCC =u g

[0108] Grid voltage u g and the grid current i g As shown below:

[0109] u g =U1cos(2πf1t)+U p cos(2πf p t+θ up )

[0110] i g =I1cos(2πf1t+θ i1 )+I p cos(2πf p t+θ ip )

[0111] Where U1 is the voltage amplitude at the fundamental frequency f1, U p and θ up is the disturbance frequency f p I1 is the voltage amplitude and phase at the fundamental frequency f1, I p and θ ip is the disturbance frequency f p The current amplitude and phase at .

[0112] Based on harmonic linearization, the above formula can be written in frequency domain:

[0113]

[0114]

[0115] Where, U1=U1 / 2, U p =(U p / 2)e ±jθup , I1=(I1 / 2)e ±jθi1 , I p =(I p / 2)e ±jθip .

[0116] Figure 2 As shown in the single-phase PLL control block diagram, the orthogonal signal generator QSG is used to generate an input signal u with the base frequency ω1. PCC The α-axis component with the same phase and the input signal u with the phase lagging behind the fundamental frequency ω1 PCC 90° β-axis component.

[0117] In SOGI-PLL, QSG is implemented by SOGI. Figure 3 The following is the SOGI control block diagram. PCC to u α and u β The transfer function is as follows:

[0118]

[0119]

[0120] Figure 4 and Figure 5 H α (s) and H β (s) Bode plots at different k parameters. At the fundamental frequency, H α (s) and H β The amplitudes of (s) are all 0dB, and the phases are 0° and -90° respectively, which meet the requirements of QSG.

[0121] from Figure 4 It can be seen that H α (s) is a bandpass filter whose bandwidth is affected by the parameter k. According to the definition of bandwidth, H α (s) lower cutoff frequency f lα for

[0122]

[0123] Similarly, the upper cutoff frequency f uα for

[0124]

[0125] Therefore, H α (s) Bandwidth is

[0126]

[0127] From the above formula and Figure 4 It can be seen that as the parameter k increases, H α (s) The bandwidth gradually increases.

[0128] Figure 5 Shown H β (s) is a second-order low-pass filter with an upper cutoff frequency f uβ for

[0129]

[0130] With H α (s) The conclusion is similar. As the parameter k increases, H β (s) The bandwidth is also gradually increasing.

[0131] According to H α (s) and H β (s),u α and u β The frequency domain form is as follows:

[0132]

[0133]

[0134] Due to the existence of voltage disturbance, it is assumed that the phase difference of the PLL output is

[0135] Δθ=θ PLL -θ1

[0136] Among them, θ1=2πf1t, θ PLL is the phase-locked loop output phase.

[0137] To solve the nonlinear problem in Parker transform, the transformation matrix can be divided into two parts as follows:

[0138]

[0139] Multiply u by T(θ1) α and u β , the frequency domain expression of the dq axis voltage is obtained as follows:

[0140]

[0141]

[0142] For simplicity, assume that F1(s) and F2(s) are as follows:

[0143]

[0144] Considering Δθ, according to the Park transformation matrix, we can get

[0145] u q (t)≈-Δθ(t)u dv (t)+u qv (t)

[0146] Assume that the transfer function from input voltage to Δθ is as follows in the frequency domain:

[0147]

[0148] Among them, G p1 (s) and G p2 (s) needs further confirmation. Combining the above two equations, we can get

[0149]

[0150] according to Figure 4 , we can get

[0151]

[0152] Combining the above two equations, we can deduce G p1 (s) and G p2 (s) are as follows:

[0153]

[0154]

[0155] in,

[0156]

[0157] We can calculate cos(θ PLL ) is expressed in the frequency domain as follows:

[0158]

[0159] Therefore, the transfer function of SOGI-PLL is as follows:

[0160]

[0161] Let 2ζω n =U1K p ,,ω n2 =U1K i , s′=s-jω0, then T PLL (s) can be written as follows:

[0162]

[0163] G SOGI-PLL (s′) is a typical second-order system. Considering the steady-state performance and system dynamic performance, ζ=0.707 is generally taken. SOGI-PLL The closed-loop bandwidth of (s′) is

[0164]

[0165] In this embodiment, f b Select 80Hz. n =U1K p ,ω n 2 =U1K i , get K p =0.4164, K i =26.9735.

[0166] Figure 6 The frequency domain control block diagram of the grid-connected inverter is shown, which can be simplified as Figure 7 ,in

[0167]

[0168]

[0169] In the formula, Z L1 =sL1,Z L2 =sL2,Z c =1 / sC f +R d .Depend on Figure 7 It can be seen that the grid current i g for

[0170]

[0171] Where T = G X1 G X2 .

[0172] Substituting the frequency domain expressions of the grid voltage and current into the above equation, we can get the impedance of the LCL inverter as

[0173]

[0174] Among them, G SOGI-PLL G can be formed by different parameters k in SOGI kreplace.

[0175] Figure 8 Shown Figure 1 The equivalent circuit diagram of the inverter is shown in Figure 1. If the grid is weak, the grid impedance cannot be ignored. Assume that the grid impedance is pure inductance to analyze the worst case. According to Figure 8 , we can get

[0176]

[0177] If Z g / Z p If the Nyquist stability criterion is met, the grid-connected inverter system will remain stable. Assume that Z g and Z p The intersection frequency is f c , then f c The phase margin (PM) at

[0178] PM=|-180°+arg[Z g (j2πf c )]-arg[Z p (j2πf c )]|

[0179] =90°+arg[Z p (j2πf c )]

[0180] In order to ensure the stability of the grid-connected inverter system, the inverter c The phase at needs to be much larger than -90°.

[0181] In order to verify the above theoretical results, a simulation based on Figure 1 The grid-connected inverter model using SOGI-PLL is shown in Figure 1. The inverter impedance with parameter k1 is defined as Z P1 , the inverter impedance with parameter k2 is defined as Z P2 .

[0182] Fig. 9 Shown is Z P2 Comparison of theoretical results and simulation results. The purple dots and blue curves represent Z P2 The simulation results and theoretical results of Fig. 9 It can be seen that the theoretical results are correct.

[0183] Fig.10 Shown is Z P1 ,,Z P2 and Z g The impedance curve of Z g and ZP1 The intersection frequency is f1 = 71 Hz. P1 The phase margin of is very small, only 15°, so the system is unstable. On the contrary, for the inverter with smaller SOGI bandwidth, and Z P1 In comparison, in Z g and Z P2 At the intersection frequency f2=87Hz, the phase margin is sufficient, reaching 70°, so the grid-connected inverter is stable.

[0184] Fig.11 (a) and 12(a) show the output waveforms of the two inverters under weak grid (SCR = 1.25). Fig.11 (a) It can be seen that the inverter with a larger SOGI bandwidth will produce sub-supersynchronous oscillation, and FFT analysis shows that the main oscillation frequencies are 39Hz and 61Hz. Fig.12 (a), The inverter with smaller SOGI bandwidth is stable. Fig.12 (b) shows that the inverter current waveform with smaller SOGI bandwidth is free of harmonics.

[0185] This embodiment uses the harmonic linearization method to derive the impedance model of the single-phase grid-connected inverter based on SOGI-PLL, and analyzes the sub-supersynchronous oscillation suppression capability of single-phase inverters with different bandwidths. The SOGI bandwidth is discussed and the SOGI-PLL model is derived. The impedance of the SOGI-PLL inverter is derived and the stability of the system is analyzed. The rationality of the theoretical impedance of the inverter is verified, and the performance of inverters with different SOGI bandwidths is compared. The model built in Matlab / Simulink shows that under the same control parameters, the smaller the SOGI bandwidth, the more stable the system.

[0186] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A single-phase inverter oscillation suppression strategy based on a second-order generalized integrator, wherein the single-phase inverter is provided with a phase-locked loop based on a second-order generalized integrator, characterized in that: The single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator; The expression of the transfer function of the second-order generalized integrator is: In the formula, is the Laplace operator, for Axis component transfer function, for Axis component transfer function, is the fundamental frequency, is the control parameter of the second-order generalized integrator; The single-phase inverter oscillation suppression strategy is specifically to reduce the parameter of the second-order generalized integrator k , suppressing oscillation of the single-phase inverter; The single-phase inverter oscillation suppression strategy is specifically as follows: after the single-phase inverter is connected to the grid, the impedance of the single-phase inverter is calculated according to the single-phase inverter impedance model, so as to judge the stability of the single-phase inverter; if the single-phase inverter is in an unstable state, the oscillation of the single-phase inverter is suppressed by reducing the bandwidth of the second-order generalized integrator.

2. The single-phase inverter oscillation suppression strategy based on a second-order generalized integrator according to claim 1, characterized in that: The single-phase inverter is an LCL type single-phase inverter, and the LCL type single-phase inverter includes an LCL filter. The expression of the impedance model of the single-phase inverter is: In the formula, is the impedance of the single-phase inverter, is the transfer function of the phase-locked loop based on the second-order generalized integrator, is the Laplace operator, L 1 is the first inductor of the LCL filter, L 2 is the second inductor of the LCL filter, C f is the capacitance of the LCL filter, R d is the resistance of the LCL filter, is the inverter output current amplitude, is the pulse width modulation coefficient, is the current loop transfer function.

3. The single-phase inverter oscillation suppression strategy based on a second-order generalized integrator according to claim 2, characterized in that: The expression of the transfer function of the phase-locked loop based on the second-order generalized integrator is: In the formula, for Axis component transfer function, for Axis component transfer function, is the base frequency The voltage amplitude at is the fundamental angular frequency and , is the control parameter of the second-order generalized integrator, is the open-loop transfer function of the phase-locked loop.

4. A single-phase inverter oscillation suppression device based on a second-order generalized integrator, wherein the single-phase inverter is provided with a phase-locked loop based on a second-order generalized integrator, characterized in that: The single-phase inverter oscillation suppression device comprises a memory and a processor, wherein the memory stores a computer program, and the processor calls the computer program to execute a single-phase inverter oscillation suppression strategy, wherein the single-phase inverter oscillation suppression strategy is to suppress the oscillation of the single-phase inverter by reducing the bandwidth of the second-order generalized integrator; The expression of the transfer function of the second-order generalized integrator is: In the formula, is the Laplace operator, for Axis component transfer function, for Axis component transfer function, is the fundamental frequency, is the control parameter of the second-order generalized integrator; The single-phase inverter oscillation suppression strategy is specifically to reduce the parameter of the second-order generalized integrator k , suppressing oscillation of the single-phase inverter; The single-phase inverter oscillation suppression strategy is specifically as follows: after the single-phase inverter is connected to the grid, the impedance of the single-phase inverter is calculated according to the single-phase inverter impedance model, so as to judge the stability of the single-phase inverter; if the single-phase inverter is in an unstable state, the oscillation of the single-phase inverter is suppressed by reducing the bandwidth of the second-order generalized integrator.

5. The single-phase inverter oscillation suppression device based on a second-order generalized integrator according to claim 4, characterized in that: The expression of the single-phase inverter impedance model is: In the formula, is the impedance of the single-phase inverter, is the transfer function of the phase-locked loop based on the second-order generalized integrator, is the Laplace operator, L 1 is the first inductor of the LCL filter, L 2 is the second inductor of the LCL filter, C f is the capacitance of the LCL filter, R d is the resistance of the LCL filter, is the inverter output current amplitude, is the pulse width modulation coefficient, is the current loop transfer function.

6. The single-phase inverter oscillation suppression device based on a second-order generalized integrator according to claim 5, characterized in that: The expression of the transfer function of the phase-locked loop based on the second-order generalized integrator is: In the formula, for Axis component transfer function, for Axis component transfer function, is the base frequency The voltage amplitude at is the fundamental angular frequency and , is the control parameter of the second-order generalized integrator, is the open-loop transfer function of the phase-locked loop.

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