Harmonic oscillation suppression method and system for hydrogen energy grid-connected converter

Abstract

The invention discloses a harmonic oscillation suppression method and system for a hydrogen energy grid-connected converter. A corresponding remolding transfer function Gig (s) is added in a forward channel of a d-axis current controller; constructing a power transmission relation between an alternating current system and a direct current system based on the direct current side small signal model and the alternating current side power small signal model of the hydrogen energy inverter; inputting a small signal transfer function model of a voltage outer loop and a current inner loop obtained by controlling the hydrogen energy grid-connected inverter into a power transmission relation of an alternating current system and a direct current system to obtain a small signal control model of the hydrogen energy grid-connected inverter in a dq coordinate system; and determining an equivalent output admittance model of the hydrogen energy inverter based on the remolded transfer function Gig (s) and the small signal control model, obtaining a minimum return rate matrix representing the stability of the hydrogen energy grid-connected inverter through the power grid impedance and the output admittance of the hydrogen energy inverter, and determining the stability of the grid-connected converter system based on the characteristic value of the minimum return rate matrix. And suppression of harmonic oscillation is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of harmonic oscillation suppression of hydrogen energy grid-connected inverters, and specifically relates to a method and system for suppressing harmonic oscillation of a hydrogen energy grid-connected converter. Background Art

[0002] In recent years, with the rapid development of new energy fields in my country, the field of "hydrogen power generation" has emerged. The stability problem of hydrogen power generation grid-connected inverters after connecting to the power grid has become increasingly prominent, manifested in the interaction between hydrogen power generation grid-connected inverters and between hydrogen power generation grid-connected inverters and the power grid, resulting in instability of the grid-connected system, which seriously threatens the safe and stable operation of the new power system.

[0003] The control system of the hydrogen power grid-connected inverter has the characteristics of high controllability and high efficiency, but the interaction between it and the grid impedance brings great challenges to the stable operation of the hydrogen grid-connected converter. Nowadays, the main idea for improving the stability of the grid-connected inverter is to change the system control structure or add an auxiliary control loop. However, these methods still have certain technical limitations in practical applications. First of all, although changing the system control structure can improve the stability of the system, large-scale structural changes may increase the complexity of the system control structure, thereby affecting the real-time control and increasing the difficulty of modeling; and the stability improvement method of adding an auxiliary control loop is very likely to introduce new feedback variables, add additional sensors, and increase the control cost. In addition, the wide range of grid impedance changes is likely to make it difficult for traditional control strategies to adapt, and it is urgent to develop more flexible control algorithms to achieve efficient and stable operation of hydrogen grid-connected inverters.

[0004] With the high penetration rate of new energy access, the power grid has shown increasingly weak characteristics, and the negative impact of grid impedance on new energy grid-connected converters cannot be ignored. Especially when the grid impedance is large, it is very easy to cause the inverter and grid impedance to interact and cause system instability.

[0005] Therefore, how to improve the stability of hydrogen grid-connected inverters? d It is a technical problem that needs to be solved urgently to optimize the simple structure of the grid-connected inverter control system from the axis and to improve the stability of the hydrogen energy inverter without adding additional complex auxiliary control loop structure.

[0006] There is an existing method for improving the stability of inverters based on grid-connected current feedforward. This scheme takes a three-phase LCL grid-connected inverter as an example. By building a small signal mathematical model of the grid-connected system, it reveals the inherent mechanism that the increase in grid impedance leads to the weakening of the stability of the grid-connected inverter. In order to improve the stability of the grid-connected system, a grid-connected current feedforward damping control loop is added to the current inner loop to reshape dq Shaft impedance model, the transfer function model of the feedforward damping link is:G AD (s)= k AD s / [ K inv ( s + ω d )]; dq The impedance model is dq The equivalent input impedance of the Thevenin or Norton equivalent circuit of the grid-connected inverter constructed under the coordinates.

[0007] By adding the feedforward damping control link, the adaptability range of the grid-connected inverter to the grid impedance is improved. However, since this technology adds a differential link in the damping control link, it is very likely to amplify the high-frequency noise of the grid-connected current, which may not be conducive to eliminating the negative impact of the disturbance signal on the current waveform quality.

[0008] The existing methods for improving the stability of new energy grid-connected inverters mainly include three categories: 1) Stability improvement method of optimizing control structure; 2) Add a method to improve the stability of the auxiliary control loop; 3) Stability improvement method by optimizing controller parameters.

[0009] First, regarding the stability improvement method of optimizing the control structure, this type of method improves the stability by modifying the control loop structure of the grid-connected inverter as a whole. For example, modifying the current-controlled inverter to a complex inverter control form of reactive voltage control is very likely to face the problem of complex system structure and increased modeling difficulty, and will also lead to the overall recompilation of the DSP control program.

[0010] Secondly, regarding the stability improvement method of adding auxiliary control loops, this type of method improves the stability of the grid-connected inverter by introducing additional auxiliary control variables and supporting transfer function models, which is very likely to lead to an increase in the number of additional sensors. In addition, the introduction of additional auxiliary control variables greatly increases the difficulty of small signal modeling.

[0011] Finally, for the stability improvement method of optimizing controller parameters, it is first necessary to analyze the influence mechanism of different control link parameters on the stability of the grid-connected inverter, and then modify the corresponding control loop parameters according to the system design requirements to achieve the stability improvement of the grid-connected inverter, such as reducing the control bandwidth of the phase-locked loop, which places high theoretical requirements on technical developers. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide a method and system for suppressing harmonic oscillation of a hydrogen energy grid-connected inverter in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problem that after the hydrogen energy grid-connected inverter is connected to the grid, the interaction with the grid impedance occurs, resulting in the weakening of the stability of the hydrogen energy grid-connected inverter.

[0013] The present invention adopts the following technical solutions: A method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter comprises the following steps: exist d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); The power transmission relationship between the AC system and the DC system is constructed based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; The small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter is input into the power transmission relationship between the AC system and the DC system. dq Small signal control model in coordinate system; Based on the reshaping transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

[0014] Preferably, reshape the transfer function G ig ( s ) is calculated as follows:

[0015] in, T 1~ T 4 is the reshaping transfer function G ig ( s ) coefficient.

[0016] Preferably, the power transmission relationship between the AC system and the DC system is as follows:

[0017] in, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the DC side current disturbance value, is the amplitude of the triangular wave carrier signal, for d The steady-state value of the axis modulation signal, for q The steady-state value of the axis modulation signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, Inverter bridge for hydrogen energy grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Steady-state value of shaft output current.

[0018] Preferably, the small signal model of the DC side of the hydrogen energy inverter is:

[0019] in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power, is the steady-state value of the DC side current, is the DC side voltage disturbance value, is the DC side current disturbance value, It is the DC side voltage stabilizing capacitor.

[0020] Preferably, the AC side power P o The small signal model is:

[0021] in, For the bridge arm of hydrogen energy grid-connected converter d Shaft output voltage, For the bridge arm of hydrogen energy grid-connected converter q Shaft output voltage, Inverter bridge for hydrogen energy grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the modulation gain.

[0022] Preferably, for:

[0023] in, is a complex frequency domain variable, is the DC side stabilizing capacitor, is the steady-state value of the DC side current.

[0024] Preferably, the hydrogen energy grid-connected inverter is dq The small signal control model in the coordinate system is:

[0025] in, V Md0 , V Mq0 , I 1d , I 1q are the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current, is the disturbance value of the grid-connected current reference value, is the voltage outer loop PI controller transfer function, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the amplitude of the triangular wave carrier signal, Inverter bridge for hydrogen energy grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the equivalent transfer function between the inverter bridge output current disturbance value of the hydrogen energy grid-connected converter and the grid-connected current disturbance value, is the equivalent transfer function between the modulation signal disturbance value and the grid-connected current disturbance value.

[0026] Preferably, the transfer function model of each link is as follows:

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] in, is the small signal disturbance introduced by the phase-locked loop at the current reference value, is the PI controller transfer function of the phase-locked loop, The grid current is d Steady-state value on the axis, is a complex variable, is the voltage amplitude at the grid connection point, The grid current is q Steady-state value on the axis, is the small signal disturbance introduced by the phase-locked loop at the modulation signal, for q The steady-state value of the axis modulation signal, for d The steady-state value of the axis modulation signal, It is the sampling and calculation delay link in the pulse width modulation process. is the sampling period, For filter inductance L 1 in dq The admittance matrix under the domain, is the filter inductor on the converter side, is the fundamental angular frequency, For filter inductance L 2 in dq The admittance matrix under the domain, is the grid-side filter inductor, is the impedance matrix of the filter capacitor branch, is the damping resistor, is the filter capacitor, For passing d The equivalent matrix of the current control loop controller after the shaft current is reshaped, for d PI controller for the shaft current control loop, for d The transfer function of the shaft current reshaping link, for q PI controller for the axis current control loop.

[0034] Preferably, the hydrogen energy inverter output admittance Y invdq for:

[0035] in, is the equivalent transfer function, is the second-order identity matrix, is the impedance matrix of the filter capacitor branch, For filter inductance L 1 in dq The admittance matrix under the domain, is the equivalent transfer function.

[0036] In a second aspect, an embodiment of the present invention provides a hydrogen energy grid-connected converter harmonic oscillation suppression system, comprising: Function module, in d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); The power module builds the power transmission relationship between the AC system and the DC system based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; The control module inputs the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter into the power transmission relationship between the AC system and the DC system to obtain the hydrogen energy grid-connected inverter. dq Small signal control model in coordinate system; Output module, based on the obtained reshaped transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the hydrogen energy grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

[0037] Preferably, reshape the transfer function G ig ( s ) is calculated as follows:

[0038] in, T 1~ T 4 is the reshaping transfer function G ig ( s ) coefficient.

[0039] Preferably, the power transmission relationship between the AC system and the DC system is as follows:

[0040] in, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the DC side current disturbance value, is the amplitude of the triangular wave carrier signal, for d The steady-state value of the axis modulation signal, forq The steady-state value of the axis modulation signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Steady-state value of shaft output current.

[0041] Preferably, the small signal model of the DC side of the hydrogen energy inverter is:

[0042] in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power, is the steady-state value of the DC side current, is the DC side voltage disturbance value, is the DC side current disturbance value, is the DC side voltage stabilizing capacitor; AC side power P o The small signal model is:

[0043] in, For the bridge arm of hydrogen energy grid-connected converter d Shaft output voltage, For the bridge arm of hydrogen energy grid-connected converter q Shaft output voltage, Inverter bridge for hydrogen grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the modulation gain; for:

[0044] in, is a complex frequency domain variable, is the DC side stabilizing capacitor, is the steady-state value of the DC side current.

[0045] Preferably, the hydrogen energy grid-connected inverter is dq The small signal control model in the coordinate system is:

[0046] in, V Md0 , V Mq0 , I 1d , I 1q are the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current, is the disturbance value of the grid-connected current reference value, is the voltage outer loop PI controller transfer function, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the amplitude of the triangular wave carrier signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the equivalent transfer function between the inverter bridge output current disturbance value of the hydrogen energy grid-connected converter and the grid-connected current disturbance value, is the equivalent transfer function between the modulation signal disturbance value and the grid-connected current disturbance value.

[0047] Preferably, the transfer function model of each link is as follows:

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] in, is the small signal disturbance introduced by the phase-locked loop at the current reference value, is the PI controller transfer function of the phase-locked loop, The grid current is d Steady-state value on the axis, is a complex variable, is the voltage amplitude at the grid connection point, The grid current is q Steady-state value on the axis, is the small signal disturbance introduced by the phase-locked loop at the modulation signal, for q The steady-state value of the axis modulation signal, for d The steady-state value of the axis modulation signal, It is the sampling and calculation delay link in the pulse width modulation process. is the sampling period, For filter inductance L 1 in dq The admittance matrix under the domain, is the filter inductor on the converter side, is the fundamental angular frequency, For filter inductance L 2 in dq The admittance matrix under the domain, is the grid-side filter inductor, is the impedance matrix of the filter capacitor branch, is the damping resistor, is the filter capacitor, For passing d The equivalent matrix of the current control loop controller after the shaft current is reshaped, for d PI controller for the shaft current control loop, for d The transfer function of the shaft current reshaping link, for q PI controller for the axis current control loop.

[0055] Preferably, the hydrogen energy inverter output admittance Y invdq for:

[0056] in, is the equivalent transfer function, is the second-order identity matrix, is the impedance matrix of the filter capacitor branch, For filter inductance L 1 in dq The admittance matrix under the domain, is the equivalent transfer function.

[0057] In a third aspect, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter when executing the computer program.

[0058] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, including a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter.

[0059] In a fifth aspect, a chip comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter when executing the computer program.

[0060] In a sixth aspect, an embodiment of the present invention provides an electronic device, including a computer program, which, when executed by the electronic device, implements the steps of the above-mentioned method for suppressing harmonic oscillation of the hydrogen energy grid-connected converter.

[0061] Compared with the prior art, the present invention has at least the following beneficial effects: A method for suppressing harmonic oscillation of hydrogen energy grid-connected converter by reshaping d The axis current loop realizes asymmetric control of the current loop, suppresses the negative impact of grid impedance on the hydrogen energy grid-connected converter, and proves that the proposed harmonic oscillation suppression method can significantly improve the stability of the hydrogen energy grid-connected converter and expand the adaptability to grid impedance by constructing the Nyquist curve of the eigenvalue of the minimum loop gain matrix model.

[0062] Further, by d Axis introduces impedance reshaping link G ig ( s ) can reshape the output impedance of the hydrogen energy grid-connected converter, improve the damping characteristics of the grid-connected converter system, promote the adaptability of the grid-connected converter system to the grid impedance, and suppress harmonic oscillations.

[0063] Furthermore, by establishing the power transmission relationship between the AC system and the DC system, the dynamics of the DC voltage output by the DC side fuel cell can be taken into account in the model of the entire grid-connected converter system, so that the constructed model can reflect the influence of the DC side voltage regulation characteristics on the stability of the hydrogen energy grid-connected converter under different grid impedances.

[0064] Furthermore, by constructing a hydrogen grid-connected converter dq The small signal control model under the coordinate can realize the construction of the equivalent output impedance model of the hydrogen energy grid-connected converter, and lays a theoretical foundation for the construction of the minimum loop gain matrix model that reflects the stability of the grid-connected converter system.

[0065] Furthermore, the transfer function model of each link can be used to facilitate the construction of hydrogen energy grid-connected converter. dqThe small signal control block diagram in the coordinate system can conveniently calculate the equivalent output impedance model of the hydrogen energy grid-connected converter with the help of the excellent characteristics of the control block diagram with clear structure and clear input and output process.

[0066] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0067] In summary, the present invention significantly improves the ability of the hydrogen energy grid-connected inverter to cope with grid impedance, ensuring safe and efficient grid connection of the hydrogen energy grid-connected inverter.

[0068] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 The present invention has d The control structure diagram of the hydrogen energy grid-connected converter system with shaft impedance reshaping; Figure 2 It is the PLL control structure diagram; Figure 3 This is the block diagram of the small signal control of the inner current loop of the hydrogen energy grid-connected inverter; Figure 4 This is the small signal control block diagram of the hydrogen grid-connected inverter; Figure 5 does not include d Axis impedance reshaping G ig ( s ) of the hydrogen grid-connected inverter stability analysis results, where (a) is L GNC analysis curve when g=12mH, (b) is L GNC analysis curve when g=13mH; Figure 6 does not include d Axis impedance reshaping G ig ( s ) of the hydrogen energy grid-connected inverter output current waveform, where (a) is L The grid-connected current waveform when g=12mH, (b) is L Grid-connected current waveform when g=13mH; FIG. 7 is a diagram showing the stability analysis results of a hydrogen energy grid-connected inverter when the method of the present invention is used, wherein (a) is L GNC analysis curve when g=20mH, (b) is L GNC analysis curve when g=22mH; FIG8 is a diagram showing the output current waveform of the hydrogen energy grid-connected inverter when the method of the present invention is used, wherein (a) is L The grid-connected current waveform when g=20mH, (b) isL Grid-connected current waveform when g=22mH.

[0070] Fig. 9 A schematic diagram of a computer device provided by an embodiment of the present invention; Fig.10 The block diagram of a chip provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0071] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0073] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0074] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0075] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0076] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0077] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0078] See also Figure 1 , in the d In the control structure diagram of the hydrogen grid-connected converter system with shaft impedance reshaping, the disturbance model of hydrogen power generation is represented by an equivalent DC power supply. I dc To perform equivalent, the power grid uses an ideal voltage source u g Series grid impedance Z g The circuit is equivalent.

[0079] in, C dc Represents the DC side voltage stabilizing capacitor, v dc Indicates the DC capacitor voltage; u inv Indicates the output port voltage of the hydrogen energy inverter. i 1 indicates the inductor current on the inverter side; R d is the passive damping resistor; i 2 indicates the grid-connected current output by the hydrogen energy inverter. Z g Indicates the line grid impedance; V pcc Indicates the voltage at the public grid connection point; U g is the grid voltage.

[0080] In the voltage outer loop control system, v dcref Indicates the DC capacitor voltage reference value; G dc (s) represents the DC capacitor voltage control loop PI controller (G dc ( s )= k pdc + k idc / s); I 2dref Indicates the grid-connected current reference value d Axis component; I 2qref Indicates the grid-connected current reference value q Axis component; i 2d , i 2q Respectively represent the grid-connected current d , q The projection component on the axis; G d ( s )express d Axis current regulator ( G id ( s )= k pd + k id / s), G q ( s )express q Axis current regulator ( G iq ( s )= k pq + k iq / s); G pll (s) is the PLL small signal disturbance transfer function model; V Md , V Mq for d axis, q Axis input PWM modulation signal; K PWM is the pulse width modulation gain; θ Indicates the phase angle of the phase-locked loop PLL output. The specific internal structure of PLL is as follows: Figure 2 shown.

[0081] in, G PI (s)= k P-G + k i-G / s is the internal PI controller of PLL; k P-Gis the proportionality coefficient, k i-G is the integration coefficient.

[0082] When the voltage at the PCC point is slightly disturbed, the phase-locked loop (PLL) generates a G signal that affects the stability of the grid-connected inverter control system. pll (s).

[0083] Considering the influence of PLL small signal disturbance on the stability of grid-connected inverter, the state variables of hydrogen grid-connected converter system are derived. x In the power grid dq Coordinate system and converter dq The relationship in the coordinate system is: (1) Among them, the superscript ' s 'Representative system dq State quantity in the coordinate system, superscript ' c 'Represents the grid-connected inverter dq The state quantity in the coordinate system, 'Δ' represents a small disturbance signal.

[0084] G pll (s) is expressed as: (2) See also Figure 3 The present invention provides a method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter, comprising the following steps: S1. d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); Figure 3 In G ig ( s ) is the present invention d The shaft impedance remodeling stability improvement method only needs to be d A corresponding reshaping transfer function link is added to the forward channel of the axis current controller to achieve the purpose of improving stability; it has the technical characteristics of simple control structure and flexible operation.

[0085] Reshape the transfer function G ig ( s ) is calculated as follows: (3) in, T 1~ T 4 is the reshaping transfer function G ig ( s) coefficient.

[0086] S2. Establish the power transmission relationship between the AC system and the DC system based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; Considering the influence of hydrogen power generation on the DC side of the hydrogen grid-connected inverter, the small signal model of the DC side of the hydrogen inverter is obtained as follows: (4) in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power.

[0087] AC side power P o The small signal model is: (5) According to equations (4) and (5), the power transmission relationship between the AC system and the DC system is established, as shown in equation (6).

[0088] (6) Rewrite equation (6) into a matrix as shown in equation (7).

[0089] (7) K dc The expression of (s) is: (8) S3, input the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter into the power transmission relationship between the AC system and the DC system obtained in step S2, and obtain the hydrogen energy grid-connected inverter in dq Small signal control model in coordinate system; according to Figure 1 The small signal transfer function model of the voltage outer loop and the current inner loop obtained by the control of the China Hydrogen Energy grid-connected inverter is shown in equation (9).

[0090] (9) Substituting equation (9) into equation (6) yields equation (10).

[0091] (10) in, V Md0 , V Mq0 , I 1d , I1q They represent the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current respectively, and their expressions are shown in equations (11) and (12).

[0092] (11) (12) According to the above model derivation, the hydrogen grid-connected inverter is dq Small signal control model in coordinate system, such as Figure 4 shown.

[0093] The transfer function model of each link is as follows: (13) (14) (15) (16) (17) (18) (19) S4, based on the small signal control model obtained in step S3, the equivalent output admittance model of the hydrogen energy inverter is obtained, and the equivalent output admittance model of the hydrogen energy inverter is obtained through the grid impedance Z gdq Output admittance of hydrogen energy inverter Y invdq The minimum return rate matrix expression that characterizes the stability of the hydrogen energy grid-connected inverter is obtained by multiplication. The stability of the system is determined by obtaining the eigenvalue of the minimum return rate matrix and judging whether its Nyquist curve surrounds the point (-1, j0).

[0094] based on Figure 4 The equivalent output admittance model of the hydrogen energy inverter obtained by the small signal control of the hydrogen energy grid-connected inverter is: (20) (twenty one) Through the grid impedance Z gdq Output admittance of hydrogen energy inverter Y invdq The minimum return rate matrix expression that characterizes the stability of hydrogen energy grid-connected inverter is obtained by multiplying: L (s)= Y invdq (s) Z gdq ( s ); by obtaining L(s) The eigenvalue of the minimum return rate matrix and determine whether its Nyquist curve surrounds the point (-1, j0) to determine the stability of the system.

[0095] In another embodiment of the present invention, a hydrogen energy grid-connected converter harmonic oscillation suppression system is provided, which can be used to implement the above-mentioned hydrogen energy grid-connected converter harmonic oscillation suppression method. Specifically, the hydrogen energy grid-connected converter harmonic oscillation suppression system includes a function module, a power module, a control module and an output module.

[0096] Among them, the function module, in d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); The power module builds the power transmission relationship between the AC system and the DC system based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; Reshape the transfer function G ig ( s ) is calculated as follows:

[0097] in, T 1~ T 4 is the reshaping transfer function G ig ( s ) coefficient.

[0098] The power transmission relationship between the AC system and the DC system is as follows:

[0099] in, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the DC side current disturbance value, is the amplitude of the triangular wave carrier signal, for d The steady-state value of the axis modulation signal, for q The steady-state value of the axis modulation signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Steady-state value of shaft output current.

[0100] The small signal model of the DC side of the hydrogen energy inverter is:

[0101] in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power, is the steady-state value of the DC side current, is the DC side voltage disturbance value, is the DC side current disturbance value, is the DC side voltage stabilizing capacitor; AC side power P o The small signal model is:

[0102] in, For the bridge arm of hydrogen energy grid-connected converter d Shaft output voltage, For the bridge arm of hydrogen energy grid-connected converter q Shaft output voltage, Inverter bridge for hydrogen grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the modulation gain; for:

[0103] in, is a complex frequency domain variable, is the DC side stabilizing capacitor, is the steady-state value of the DC side current.

[0104] The control module inputs the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter into the power transmission relationship between the AC system and the DC system to obtain the hydrogen energy grid-connected inverter. dq Small signal control model in coordinate system; Hydrogen grid-connected inverter dq The small signal control model in the coordinate system is:

[0105] in, V Md0 ,V Mq0 , I 1d , I 1q are the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current, is the disturbance value of the grid-connected current reference value, is the voltage outer loop PI controller transfer function, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the amplitude of the triangular wave carrier signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the equivalent transfer function between the inverter bridge output current disturbance value of the hydrogen energy grid-connected converter and the grid-connected current disturbance value, is the equivalent transfer function between the modulation signal disturbance value and the grid-connected current disturbance value.

[0106] The transfer function model of each link is as follows:

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] in, is the small signal disturbance introduced by the phase-locked loop at the current reference value, is the PI controller transfer function of the phase-locked loop, The grid current is d Steady-state value on the axis, is a complex variable, is the voltage amplitude at the grid connection point, The grid current is q Steady-state value on the axis, is the small signal disturbance introduced by the phase-locked loop at the modulation signal, for q The steady-state value of the axis modulation signal, for d The steady-state value of the axis modulation signal, It is the sampling and calculation delay link in the pulse width modulation process. is the sampling period, For filter inductance L 1 in dq The admittance matrix under the domain, is the filter inductor on the converter side, is the fundamental angular frequency, For filter inductance L 2 in dq The admittance matrix under the domain, is the grid-side filter inductor, is the impedance matrix of the filter capacitor branch, is the damping resistor, is the filter capacitor, For passing d The equivalent matrix of the current control loop controller after the shaft current is reshaped, for d PI controller for the shaft current control loop, for d The transfer function of the shaft current reshaping link, for q PI controller for the axis current control loop.

[0114] Output module, based on the obtained reshaped transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the hydrogen energy grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

[0115] Output admittance of hydrogen energy inverter Y invdq for:

[0116] in, is the equivalent transfer function, is the second-order identity matrix, is the impedance matrix of the filter capacitor branch, For filter inductance L 1 in dq The admittance matrix under the domain, is the equivalent transfer function.

[0117] In another embodiment of the present invention, a terminal device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the harmonic oscillation suppression method of the hydrogen energy grid-connected converter, including: exist d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); Based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power, the power transmission relationship between the AC system and the DC system is constructed; the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter is input into the power transmission relationship between the AC system and the DC system, and the hydrogen energy grid-connected inverter is obtained. dq Small signal control model in coordinate system; based on reshaping transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

[0118] See also Fig. 9, the terminal device is a computer device, and the computer device 60 of this embodiment includes: a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When the computer program 63 is executed by the processor 61, the method for suppressing harmonic oscillation of the hydrogen energy grid-connected converter in the embodiment is implemented. To avoid repetition, it is not described one by one here. Alternatively, when the computer program 63 is executed by the processor 61, the functions of each model / unit in the system for suppressing harmonic oscillation of the hydrogen energy grid-connected converter in the embodiment are implemented. To avoid repetition, it is not described one by one here.

[0119] The computer device 60 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will appreciate that Fig. 9 This is only an example of the computer device 60 and does not constitute a limitation of the computer device 60. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0120] The processor 61 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0121] The memory 62 may be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 may also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc., equipped on the computer device 60.

[0122] Furthermore, the memory 62 may include both an internal storage unit of the computer device 60 and an external storage device. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 may also be used to temporarily store data that has been output or is to be output.

[0123] See also Fig.10 , the terminal device is a chip, and the chip 600 of this embodiment includes a processor 622, which may be one or more, and a memory 632 for storing a computer program executable by the processor 622. The computer program stored in the memory 632 may include one or more modules, each corresponding to a set of instructions. In addition, the processor 622 may be configured to execute the computer program to execute the above-mentioned hydrogen energy grid-connected converter harmonic oscillation suppression method.

[0124] In addition, the chip 600 may further include a power supply component 626 and a communication component 650, wherein the power supply component 626 may be configured to perform power management of the chip 600, and the communication component 650 may be configured to implement communication, for example, wired or wireless communication, of the chip 600. In addition, the chip 600 may further include an input / output interface 658. The chip 600 may operate based on an operating system stored in the memory 632.

[0125] In another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium, which is a memory device in a terminal device for storing programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and the extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs. It should be noted that the computer-readable storage medium here can be a high-speed RAM memory, or a non-volatile memory (Non-VolatileMemory), such as at least one disk memory.

[0126] One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the corresponding steps of the method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter in the above embodiment; one or more instructions in the computer-readable storage medium are loaded and executed by a processor as follows: exist d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); Based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power, the power transmission relationship between the AC system and the DC system is constructed; the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter is input into the power transmission relationship between the AC system and the DC system, and the hydrogen energy grid-connected inverter is obtained. dq Small signal control model in coordinate system; based on reshaping transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

[0127] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0128] In order to verify the technical advantages of the present invention, a three-phase hydrogen grid-connected inverter with a power of 10kW was built in Matlab / Simulink to verify the technical advantages of the present invention. d The effectiveness of the stability improvement method of hydrogen energy grid-connected inverter with shaft impedance reshaping. The main parameters of the system are shown in Table 1.

[0129] Table 1 Main parameters of the system

[0130] To verify the present invention d The correctness and effectiveness of the stability improvement method of hydrogen energy grid-connected inverter with shaft impedance reshaping are shown in Figure 5. d Axis impedance reshaping G ig ( s ) of hydrogen grid-connected inverter, namely Figure 1 No red frame G ig ( s ) link, the stability analysis results when the grid impedance is 12mH and 13mH respectively.

[0131] In order to further prove the correctness of the stability analysis method based on the generalized Nyquist criterion, Figure 6 shows the stability analysis method without including d Axis impedance reshaping Gig ( s )'s grid-connected output current waveform when the grid impedance is 12mH and 13mH respectively.

[0132] It can be seen from Figure 6 that at this time, the hydrogen energy grid-connected inverter has a grid impedance of L g When the output current is 12mH, it is stable. When the output current is 13mH, the output current waveform becomes obviously unstable, which verifies the correctness of the theoretical analysis in Figure 5.

[0133] When the present invention is used d When the stability method of the hydrogen energy grid-connected inverter with shaft impedance reshaping is used, Figure 7 shows the stability analysis results of the hydrogen energy grid-connected inverter when the grid impedance is 20mH and 21mH respectively.

[0134] According to the generalized Nyquist curve in Figure 7, it can be seen that when the grid impedance L g When it increases to 20mH, the two-dimensional return rate matrix L (s) Eigenvalue λ The Nyquist curve of 1(s) does not surround the point (-1, j0), which indicates that the hydrogen grid-connected inverter can maintain stable operation at this time. L g When it is further increased to 22mH, the eigenvalue of the two-dimensional rate matrix λ The Nyquist curve of 1(s) surrounds the point (-1, j0), which means that the hydrogen grid-connected system loses stability at this time. d Axis impedance reshaping G ig ( s ) shows that the stability improvement method proposed in the present invention has significantly increased the adaptability range of the grid-connected inverter to the grid impedance, and the stability of the system has been significantly improved.

[0135] In order to further demonstrate the effectiveness of the control method proposed in the present invention and the correctness of the theoretical analysis, FIG8 shows the corresponding grid-connected current waveform.

[0136] It can be seen from Figure 8 that at this time, the hydrogen energy grid-connected inverter has a grid impedance of L g When the voltage is 20mH, it can still output a stable current. When the voltage is 22mH, the output current waveform becomes obviously unstable, which verifies the correctness of the theoretical analysis in Figure 7.

[0137] Through the comparison and analysis of the above theory and simulation results, the patent dThe correctness and effectiveness of the stability improvement method of shaft impedance reshaping have significantly improved the adaptability of hydrogen energy grid-connected inverters to changes in grid impedance.

[0138] In summary, the method and system for suppressing harmonic oscillation of a hydrogen energy grid-connected converter of the present invention can significantly increase the adaptability of the hydrogen energy grid-connected converter to the grid impedance, can suppress the harmonic oscillation induced by the increase of the grid impedance, improve the power quality of the output voltage and current of the hydrogen energy grid-connected converter, contribute to the local consumption of hydrogen energy and the improvement of installed capacity, and provide a technical solution for the efficient utilization of hydrogen energy.

[0139] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0140] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0141] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0142] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0143] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0144] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0145] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0146] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices, and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0147] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0148] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0149] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter, characterized in that: The following steps are involved: exist d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); The power transmission relationship between the AC system and the DC system is constructed based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; The small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter is input into the power transmission relationship between the AC system and the DC system. dq Small signal control model in coordinate system; Based on the obtained reshaped transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

2. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 1, characterized in that: Reshape the transfer function G ig ( s ) is calculated as follows: in, T 1~ T 4 is the reshaping transfer function G ig ( s ) coefficient.

3. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 1, characterized in that: The power transmission relationship between the AC system and the DC system is as follows: in, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the DC side current disturbance value, is the amplitude of the triangular wave carrier signal, for d The steady-state value of the axis modulation signal, for q The steady-state value of the axis modulation signal, Inverter bridge for hydrogen energy grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen grid-connected converter q Steady-state value of shaft output current.

4. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 3, characterized in that: The small signal model of the DC side of the hydrogen energy inverter is: in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power, is the steady-state value of the DC side current, is the DC side voltage disturbance value, is the DC side current disturbance value, It is the DC side voltage stabilizing capacitor.

5. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 3, characterized in that: AC side power P o The small signal model is: in, For the bridge arm of hydrogen energy grid-connected converter d Shaft output voltage, For the bridge arm of hydrogen energy grid-connected converter q Shaft output voltage, Inverter bridge for hydrogen energy grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen energy grid-connected converter q Shaft output current disturbance value, is the modulation gain.

6. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 3, characterized in that: for: in, is a complex frequency domain variable, is the DC side stabilizing capacitor, is the steady-state value of the DC side current.

7. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 1, characterized in that: Hydrogen grid-connected inverter dq The small signal control model in the coordinate system is: in, V Md0 , V Mq0 , I 1d , I 1q are the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current, is the disturbance value of the grid-connected current reference value, is the voltage outer loop PI controller transfer function, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the amplitude of the triangular wave carrier signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the equivalent transfer function between the inverter bridge output current disturbance value of the hydrogen energy grid-connected converter and the grid-connected current disturbance value, is the equivalent transfer function between the modulation signal disturbance value and the grid-connected current disturbance value.

8. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 7, characterized in that: The transfer function model of each link is as follows: in, is the small signal disturbance introduced by the phase-locked loop at the current reference value, is the PI controller transfer function of the phase-locked loop, The grid current is d Steady-state value on the axis, is a complex variable, is the voltage amplitude at the grid connection point, The grid current is q Steady-state value on the axis, is the small signal disturbance introduced by the phase-locked loop at the modulation signal, for q The steady-state value of the axis modulation signal, for d The steady-state value of the axis modulation signal, It is the sampling and calculation delay link in the pulse width modulation process. is the sampling period, For filter inductance L 1 in dq The admittance matrix under the domain, is the filter inductor on the converter side, is the fundamental angular frequency, For filter inductance L 2 in dq The admittance matrix under the domain, is the grid-side filter inductor, is the impedance matrix of the filter capacitor branch, is the damping resistor, is the filter capacitor, For passing d The equivalent matrix of the current control loop controller after the shaft current is reshaped, for d PI controller for the axis current control loop, for d The transfer function of the shaft current reshaping link, for q PI controller for the axis current control loop.

9. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 1, characterized in that: Output admittance of hydrogen energy inverter Y invdq for: in, is the equivalent transfer function, is the second-order identity matrix, is the impedance matrix of the filter capacitor branch, For filter inductance L 1 in dq The admittance matrix under the domain, is the equivalent transfer function.

10. A hydrogen energy grid-connected converter harmonic oscillation suppression system, characterized in that: include: Function module, in d Add the corresponding reshaped transfer function in the forward channel of the axis current controller G ig ( s ); The power module builds the power transmission relationship between the AC system and the DC system based on the small signal model of the DC side of the hydrogen energy inverter and the small signal model of the AC side power; The control module inputs the small signal transfer function model of the voltage outer loop and the current inner loop obtained by controlling the hydrogen energy grid-connected inverter into the power transmission relationship between the AC system and the DC system to obtain the hydrogen energy grid-connected inverter. dq Small signal control model in coordinate system; Output module, based on the obtained reshaped transfer function G ig ( s ) and the small signal control model are used to determine the equivalent output admittance model of the hydrogen energy inverter. The minimum return rate matrix that characterizes the stability of the hydrogen energy grid-connected inverter is obtained through the grid impedance and the output admittance of the hydrogen energy inverter. The stability of the hydrogen energy grid-connected converter system is determined based on the eigenvalue of the minimum return rate matrix to achieve the suppression of harmonic oscillation.

11. The hydrogen energy grid-connected converter harmonic oscillation suppression system according to claim 10, characterized in that: Reshape the transfer function G ig ( s ) is calculated as follows: in, T 1~ T 4 is the reshaping transfer function G ig ( s ) coefficient.

12. The hydrogen energy grid-connected converter harmonic oscillation suppression system according to claim 10, characterized in that: The power transmission relationship between the AC system and the DC system is as follows: in, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the DC side current disturbance value, is the amplitude of the triangular wave carrier signal, for d The steady-state value of the axis modulation signal, for q The steady-state value of the axis modulation signal, Inverter bridge for hydrogen energy grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen energy grid-connected converter q Shaft output current disturbance value, Inverter bridge for hydrogen energy grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen energy grid-connected converter q Steady-state value of shaft output current.

13. The method for suppressing harmonic oscillation of a hydrogen energy grid-connected converter according to claim 12, characterized in that: The small signal model of the DC side of the hydrogen energy inverter is: in, P dc represents the output power of the hydrogen energy converter, P Cdc is the DC side capacitor power, is the steady-state value of the DC side current, is the DC side voltage disturbance value, is the DC side current disturbance value, is the DC side voltage stabilizing capacitor; AC side power P o The small signal model is: in, For the bridge arm of hydrogen energy grid-connected converter d Shaft output voltage, For the bridge arm of hydrogen energy grid-connected converter q Shaft output voltage, Inverter bridge for hydrogen energy grid-connected converter d Steady-state value of shaft output current, Inverter bridge for hydrogen energy grid-connected converter q Shaft output current disturbance value, is the modulation gain; for: in, is a complex frequency domain variable, is the DC side stabilizing capacitor, is the steady-state value of the DC side current.

14. The hydrogen energy grid-connected converter harmonic oscillation suppression system according to claim 10, characterized in that: Hydrogen grid-connected inverter dq The small signal control model in the coordinate system is: in, V Md0 , V Mq0 , I 1d , I 1q are the modulation signal of the hydrogen energy grid-connected inverter and the steady-state value of the inverter bridge arm output current, is the disturbance value of the grid-connected current reference value, is the voltage outer loop PI controller transfer function, is the DC side voltage disturbance value, is the steady-state value of the DC side voltage, is the equivalent transfer function including the steady-state values ​​of AC and DC voltage and current, is the amplitude of the triangular wave carrier signal, Inverter bridge for hydrogen grid-connected converter d Shaft output current disturbance value, Inverter bridge for hydrogen grid-connected converter q Shaft output current disturbance value, is the equivalent transfer function between the inverter bridge output current disturbance value of the hydrogen energy grid-connected converter and the grid-connected current disturbance value, is the equivalent transfer function between the modulation signal disturbance value and the grid-connected current disturbance value.

15. The hydrogen energy grid-connected converter harmonic oscillation suppression system according to claim 14, characterized in that: The transfer function model of each link is as follows: in, is the small signal disturbance introduced by the phase-locked loop at the current reference value, is the PI controller transfer function of the phase-locked loop, The grid current is d Steady-state value on the axis, is a complex variable, is the voltage amplitude at the grid connection point, The grid current is q Steady-state value on the axis, is the small signal disturbance introduced by the phase-locked loop at the modulation signal, for q The steady-state value of the axis modulation signal, for d The steady-state value of the axis modulation signal, It is the sampling and calculation delay link in the pulse width modulation process. is the sampling period, For filter inductance L 1 in dq The admittance matrix under the domain, is the filter inductor on the converter side, is the fundamental angular frequency, For filter inductance L 2 in dq The admittance matrix under the domain, is the grid-side filter inductor, is the impedance matrix of the filter capacitor branch, is the damping resistor, is the filter capacitor, For passing d The equivalent matrix of the current control loop controller after the shaft current is reshaped, for d PI controller for the axis current control loop, for d The transfer function of the shaft current reshaping link, for q PI controller for the axis current control loop.

16. The hydrogen energy grid-connected converter harmonic oscillation suppression system according to claim 1, characterized in that: Output admittance of hydrogen energy inverter Y invdq for: in, is the equivalent transfer function, is the second-order identity matrix, is the impedance matrix of the filter capacitor branch, For filter inductance L 1 in dq The admittance matrix under the domain, is the equivalent transfer function.

17. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform the method of any one of claims 1 to 9.

18. A computing device, characterized in that include: One or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include steps for executing the method according to any one of claims 1 to 9.

19. A chip, characterized in that: a memory having a computer program stored thereon; A processor, configured to execute the computer program in the memory to implement the steps of the method according to any one of claims 1 to 9.

20. An electronic device, characterized in that: Comprising the chip as claimed in claim 19.

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