Control method for active damping of power oscillation of grid-forming converter

Abstract

The invention discloses a control method for active damping of power oscillation of a grid-forming converter, and relates to the technical field of wind power generation. Determining an energy interaction path between an active power control loop and a reactive power control loop in the network construction type converter according to the power coupling action mechanism of the network construction type converter; constructing an energy feedback branch according to the energy interaction path; and compensating a negative damping effect generated by power coupling between the active power control loop and the reactive power control loop according to the energy feedback branch so as to realize control of active damping of power oscillation of the grid-forming type converter. The method can effectively solve the problem of high difficulty in stabilizing the network construction type converter.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation, and in particular to a control method for active damping of power oscillation of a grid-type converter. Background Art

[0002] At present, traditional wind and solar energy units connected to the grid based on grid-following converters are prone to instability in weak grid scenarios. In order to support the friendly grid connection of wind and solar, the concept of grid-building converters came into being. However, there is the influence of coupling of power electronic active and reactive control loops in grid-building converters, which can easily cause new oscillation stability problems in low-voltage short-distance transmission systems.

[0003] In the prior art, in order to suppress low-frequency oscillations and compensate for the negative damping of the system, the existing methods can be divided into three categories, namely, control parameter setting, adding additional damping control branches or additional stabilizers.

[0004] However, achieving adaptive adjustment of control parameters places high demands on the controller. Adding additional damping control branches or additional stabilizers may complicate the parameter adjustment of the grid-type converter, thereby increasing the difficulty of stabilizing the grid-type converter. Summary of the invention

[0005] Based on this, it is necessary to provide a control method for active damping of power oscillations of a grid-type converter in response to the above-mentioned technical problems. This method can effectively solve the problem that it is difficult to stabilize the grid-type converter.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a control method for active damping of power oscillation of a grid-connected converter, comprising:

[0008] According to the power coupling mechanism of the grid-connected converter, the energy interaction path between the active control loop and the reactive control loop in the grid-connected converter is determined;

[0009] According to the energy interaction path, an energy feedback branch is constructed; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive control loop;

[0010] According to the energy feedback branch, the negative damping effect caused by the power coupling between the active control loop and the reactive control loop is compensated to realize the control of the active damping of the power oscillation of the grid-connected converter.

[0011] Preferably, according to the power coupling mechanism of the grid-type converter, determining the energy interaction path between the active control loop and the reactive control loop in the grid-type converter includes:

[0012] Obtain the interactive energy expression of power coupling of grid-connected converters;

[0013] According to the small signal model of the active control loop and the reactive control loop, the oscillation phase correlation relationship between the phase angle output by the active control loop and the voltage output by the reactive control loop is determined;

[0014] The correlation between the interaction energy expression and the oscillation phase is analyzed, and the energy interaction path is determined to be the energy interaction path transmitted from the active control loop to the reactive control loop.

[0015] Preferably, the energy interaction path includes transmitting the angular frequency output by the active control loop to the reactive control loop, and the energy feedback branch is used to adjust the output of the reactive control loop according to the angular frequency output by the active control loop.

[0016] Preferably, the process of determining the power coupling mechanism of the grid-connected converter includes:

[0017] Taking time derivatives of the dynamic energy models of the active control loop and the reactive control loop, and determining the time derivatives of the dynamic energy models;

[0018] According to the time derivative of the dynamic energy model, the factors affecting the damping level of the grid-connected converter with power coupling mechanism are determined, including the rate of change of the interaction energy generated by power coupling.

[0019] Preferably, the dynamic energy model of the active control loop is:

[0020]

[0021] Among them, V p Represents the energy function of the active control loop, V s,p is the stored energy of the active control loop, V d,p is the dissipated energy of the active control loop, V t,pq is the interactive energy transferred from the reactive control loop to the active control loop, J is the virtual inertia, ω is the angular frequency, E0 is the rated output voltage, V g0 is the infinite system rated voltage, g1 is the equivalent line resistance, θ0 is the initial phase angle, θ is the phase angle of the active control loop output, D p is the damping coefficient.

[0022] The dynamic energy model of the reactive power control loop is:

[0023]

[0024] Among them, V q Represents the energy function of the reactive power control loop, V s,q is the stored energy of the reactive power control loop, V d,q is the dissipated energy of the reactive power control loop, V t,qp is the interactive energy transferred from the active control loop to the reactive control loop, K is the voltage integral coefficient, b1 is the line equivalent susceptance, V g is infinite system voltage.

[0025] Preferably, according to the energy feedback branch, the negative damping effect generated by the power coupling between the active control loop and the reactive control loop is compensated to realize the control of the active damping of the power oscillation of the grid-connected converter, including:

[0026] The rated output voltage is squared by a numerical square module, and the squared rated output voltage is multiplied by an equivalent line resistance by a multiplication gain module to obtain a first power;

[0027] The difference between the first power and the rated active power of the grid-connected converter is calculated by a subtractor to obtain a first power deviation;

[0028] The first power deviation is multiplied by a preset deviation coefficient through a scaling module to obtain a second power deviation;

[0029] The angular frequency output by the active control loop is integrated by the integration unit to obtain the phase angle;

[0030] The phase angle is multiplied by the second power deviation through a multiplier to obtain the compensation power generated by the energy feedback branch;

[0031] A voltage is generated by compensating the energy value output by the power and reactive power control loop, and a pulse width modulation signal is generated according to the voltage and the phase angle output by the active power control loop to realize the control of active damping of power oscillation of the grid-connected converter.

[0032] The present invention provides a control device for active damping of power oscillation of a grid-type converter, comprising:

[0033] A determination module, used to determine an energy interaction path between an active control loop and a reactive control loop in the grid-type converter according to a power coupling mechanism of the grid-type converter;

[0034] A construction module is used to construct an energy feedback branch according to an energy interaction path; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive control loop;

[0035] The control module is used to compensate the negative damping effect caused by the power coupling between the active control loop and the reactive control loop according to the energy feedback branch, so as to realize the control of the active damping of the power oscillation of the grid-type converter.

[0036] The present invention provides a computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the control method for active damping of power oscillation of the above-mentioned grid-connected converter is implemented.

[0037] The present invention provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the control method for active damping of power oscillation of the above-mentioned grid-connected converter when executing the program.

[0038] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0039] In the present invention, by analyzing the power coupling mechanism of the grid-type converter, the energy interaction path of the active and reactive control loops in the grid-type converter is determined, and an energy feedback branch is constructed on the basis of the energy interaction path. The negative damping effect generated by the power coupling between the active control loop and the reactive control loop is compensated by the energy feedback branch, thereby eliminating the instability between the reactive control loop and the active control loop. The present invention can ensure the stability of the grid-type converter by only constructing an energy feedback branch in the energy interaction path between the active control loop and the reactive control loop, thereby solving the problem of the difficulty of stabilizing the grid-type converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1A schematic flow chart of a control method for active damping of power oscillations of a grid-connected converter provided by the present invention;

[0042] Figure 2 A grid-connected converter system structure diagram provided by the present invention

[0043] Figure 3 A schematic diagram of a voltage phase angle amplitude-frequency curve provided by the present invention;

[0044] Figure 4 A schematic diagram of another voltage phase angle amplitude-frequency curve provided by the present invention;

[0045] Figure 5 A structural block diagram of an energy feedback model provided by the present invention;

[0046] Figure 6 A schematic diagram of the structure of an energy feedback branch provided by the present invention;

[0047] Figure 7 A schematic diagram of an energy feedback branch access position provided by the present invention;

[0048] Figure 8 A diagram of the outer loop structure of a system after introducing an energy feedback branch provided by the present invention;

[0049] Fig. 9 A waveform diagram of active power output by a grid-type converter under oscillation convergence conditions provided by the present invention;

[0050] Fig.10 A waveform diagram of active power output by a grid-type converter under oscillation divergence provided by the present invention;

[0051] Fig.11a A diagram of the change trajectory of interactive energy under an oscillation convergence condition provided by the present invention;

[0052] Fig.11b A diagram of the change trajectory of dissipated energy under an oscillation convergence condition provided by the present invention;

[0053] Fig.11c A diagram of the change trajectory of stored energy under an oscillation convergence condition provided by the present invention;

[0054] Fig.12a A diagram of the change trajectory of interactive energy under an oscillating divergence working condition provided by the present invention;

[0055] Figure 12b A diagram of the change trajectory of dissipated energy under an oscillating divergent working condition provided by the present invention;

[0056] Fig.12c A diagram of the change trajectory of stored energy under an oscillating divergent working condition provided by the present invention;

[0057] Fig.13 A schematic diagram of the change of power coupling coefficient under different conductivity parameter scenarios provided by the present invention;

[0058] Fig.14 A grid-type converter output power waveform diagram under different line parameters provided by the present invention;

[0059] Fig.15 A diagram of the change trajectory of interactive energy under an oscillation convergence condition provided by the present invention;

[0060] Fig.16 A diagram of the change trajectory of interactive energy under an oscillating divergence working condition provided by the present invention;

[0061] Fig.17 A schematic diagram of the change of the system power coupling coefficient after the energy feedback branch is introduced provided by the present invention;

[0062] Fig.18 An output power waveform diagram of a grid-type converter after introducing an energy feedback branch provided by the present invention;

[0063] Fig.19 A schematic diagram of output power variation of a grid-type converter under power mutation provided by the present invention;

[0064] Fig. 20 A schematic diagram of a control device for active damping of power oscillations of a grid-type converter provided by the present invention;

[0065] Fig.21 A schematic diagram of a computer device for implementing a control method for active damping of power oscillations of a grid-connected converter provided by the present invention.

[0066] Description of reference numerals:

[0067] 100, energy feedback branch; 101, numerical square module; 102, multiplication gain module; 103, subtractor; 104, scaling module; 105, multiplier; 106, integration unit. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only 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 making creative work are within the scope of protection of the present invention.

[0069] Existing research on the power oscillation stability of grid-connected converters mainly focuses on the analysis of the influence of the short-circuit ratio of the grid-connected system and the external loop control parameters of the grid-connected converter. However, the holistic modeling method adopted in existing research results leads to the mixing of control links, making it difficult to explain the mechanism of the interaction of control links on system stability. In addition, existing research usually ignores the influence of line resistance on stability, and the oscillation mechanism of the grid-connected converter lacks corresponding explanation.

[0070] In addition, the influence of the damping control branch introduced in the prior art on the basic response characteristics of the grid-connected converter is also lacking in verification. Therefore, the power coupling oscillation mechanism and control method of the grid-connected converter still need to be further studied.

[0071] The technical solutions provided by various embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0072] Figure 1 The present invention is a flow chart of a control method for active damping of power oscillation of a grid-connected converter, which specifically includes the following steps:

[0073] S101, determining an energy interaction path between an active control loop and a reactive control loop in the grid-connected converter according to a power coupling mechanism of the grid-connected converter.

[0074] The control method can be applied to grid-connected systems of grid-connected converters.

[0075] In an exemplary embodiment, according to constructing a dynamic energy model of a grid-connected system of a grid-connected converter, the power coupling mechanism of the grid-connected converter is analyzed, which specifically includes:

[0076] S201, construct the grid-connected system structure of the grid-connected converter, and establish the mathematical models of the active-phase angle outer loop and the reactive-voltage outer loop.

[0077] like Figure 2 As shown, Figure 2 Figure 1 is a structural diagram of a grid-connected system of a grid-connected converter. The power outer loop includes an active control loop and a reactive control loop. The active control loop is an active-phase angle outer loop, and the reactive control loop is a reactive-voltage outer loop. The phase and amplitude instructions of the output voltage are output respectively through droop control. The feedforward decoupled voltage and current double closed-loop control adjusts the internal potential output by the grid-connected converter, thereby controlling the voltage at the point of common coupling (PCC) to follow the output voltage phase and amplitude of the grid-connected converter.

[0078] Due to the fast dynamic response of the voltage and current loops inside the grid-type converter, the amplitude and phase of the PCC voltage can be approximated as the output voltage E and phase θ of the power loop control of the grid-type converter. Therefore, the present invention focuses on the influence of power coupling on system stability, considers the inner loop voltage and current loop as an ideal link, and constructs a grid-type converter control model. Among them, the active power-phase angle outer loop control model is:

[0079]

[0080] Where θ is the active loop output phase angle, P0 and P are the active power steady-state value and actual value of the grid-connected converter, J is the virtual inertia, and D p is the damping coefficient, ω0 is the rated angular frequency, and ω is the output angular frequency of the grid-type converter.

[0081] The reactive power-voltage outer loop usually adopts droop control to support the grid voltage by providing limited reactive power. Its first-order differential equation is:

[0082]

[0083] Among them, E and E0 are the actual value and rated value of the PCC point voltage output by the reactive loop, Q0 and Q are the rated value and actual value of the reactive power of the grid-type converter, K is the voltage integral coefficient, D q is the voltage droop coefficient.

[0084] According to the power flow equation of the power grid, the expressions of the active power P and reactive power Q output by the grid-connected converter taking into account the line resistance can be expressed as:

[0085]

[0086] in, is the line equivalent conductance, is the line equivalent susceptance, θ g is the voltage phase angle of the AC system, which is the reference voltage phase angle of the grid-type converter in the present invention, X1=w1·L1, w1=10π.

[0087] Substituting formula (3) into formula (1) and formula (2), the small signal model of the active control loop and reactive-voltage outer loop control submodule of the grid-connected system of the grid-connected converter can be obtained as follows:

[0088]

[0089] in,

[0090] From the above formula, we can see that there are mutual coupling terms in the active control loop and reactive control loop in the grid-connected system of the grid-connected converter. After the system is disturbed, the terminal voltage and phase angle change, and coupling occurs through the two power links, which can easily induce new damping stability problems. Therefore, it is necessary to further quantify the coupling effect between the control loops and explore the impact of power coupling on the stability of the grid-connected converter.

[0091] S202, constructing a dynamic energy model of a grid-connected converter system.

[0092] Formula (4) can be organized into the following general form:

[0093]

[0094] Among them, K L , K R and K C The interaction link that affects the output angular frequency Δω of the active loop is expressed as F L .

[0095] Through the first integration method, the interaction energy between each control loop is constructed to quantitatively characterize the interaction between the control loops.

[0096] Dividing the two equations in formula (5), we can get:

[0097]

[0098] Using the first integration method, cross-multiplying formula (6) and integrating the left and right sides of the equation at the same time, we can obtain:

[0099]

[0100] Based on formula (7), the energy function V is defined as:

[0101] V=V s -V d -V t (8)

[0102] in,

[0103]

[0104] Where Vs is the stored energy, V d is the dissipated energy, V t is the interaction energy between sub-circuits.

[0105] For the first-order system of formula (5), it can be organized into the following form:

[0106]

[0107] In the formula, K A is a constant term, and the interaction link that affects the active power output phase Δθ is expressed as F C .

[0108] The equation can be multiplied by the state variable in the differential symbol d() / dt. Then the result is multiplied by dt to obtain:

[0109] KΔEdΔE=-K A ΔE 2 dt+F C ΔEdt (11)

[0110] Then integrate both sides of formula (11) to obtain: The form is consistent with formula (7), and a similar energy function definition can be performed.

[0111] Based on the above modeling method, a dynamic energy model of the active control loop and a dynamic energy model of the reactive control loop can be obtained.

[0112] The dynamic energy model of the active control loop is:

[0113]

[0114] Among them, V p Represents the energy function of the active control loop, V s,p is the stored energy of the active control loop, V d,p is the dissipated energy of the active control loop, V t,pq is the interactive energy transferred from the reactive control loop to the active control loop, J is the virtual inertia, ω is the angular frequency, E0 is the rated output voltage, V g0 is the infinite system rated voltage, g1 is the equivalent line resistance, θ0 is the initial phase angle, θ is the phase angle of the active control loop output, D p is the damping coefficient.

[0115] The dynamic energy model of the reactive power control loop is:

[0116]

[0117] Among them, V q Represents the energy function of the reactive power control loop, V s,q is the stored energy of the reactive power control loop, V d,q is the dissipated energy of the reactive power control loop, V t,qp is the interactive energy transferred from the active control loop to the reactive control loop, K is the voltage integral coefficient, b1 is the line equivalent susceptance, V g is infinite system voltage.

[0118] S203, defining a power coupling coefficient, and quantifying the contribution of the power coupling of the grid-connected converter to the system stability.

[0119] The total dynamic energy function of the grid-connected system of the grid-connected converter is composed of the sum of the dynamic energies of the active and reactive control loops. Based on the above formulas (12) and (13), the dynamic energy models of the active control loop and the reactive control loop are time-derivated to determine the time derivative of the dynamic energy model; according to the time derivative of the dynamic energy model, the factors affecting the damping level of the grid-connected converter, which is determined by the power coupling mechanism, include the rate of change of the interactive energy generated by the power coupling.

[0120] Specifically, the time derivative of the dynamic energy model of the active control loop and the reactive control loop is essentially the time derivative of the total energy function in the dynamic energy model of the active control loop and the reactive control loop, that is, the partial derivative of the total energy function V with respect to time t in formulas (12) and (13) is calculated, and the result is shown in formula (14). It can be seen from formula (14) that the derivative of the energy function V with respect to time t is zero, which proves that the system is energy conserving.

[0121]

[0122] Where V is the total energy function of the grid-connected converter, V = V p +V q .

[0123] Based on the viewpoint of Lyapunov's second method, after the system is disturbed, the state variables deviate from the equilibrium point, the system obtains a certain amount of stored energy, and oscillates around the equilibrium point. If the stored energy gradually decays over time, the oscillation amplitude will become smaller and smaller, and when the equilibrium state is reached, the oscillation amplitude is zero, then at this equilibrium point, the system is asymptotically stable. On the contrary, if the system's stored energy continues to increase, then at this equilibrium point, the system is unstable. If the system's stored energy neither increases nor is consumed, then at this equilibrium point, the system is in a critically stable state.

[0124] From formula (14), we can see that the rate of change of system stored energy is determined by the rate of change of dissipated energy and the rate of change of interactive energy. Combining formulas (12) and (13), we can see that the rate of change of dissipated energy is always negative, that is, it presents a positive damping effect. Therefore, the overall damping level of the system mainly depends on the rate of change of interactive energy generated by power coupling, which is defined as the power coupling coefficient Power coupling coefficient The expression is as follows:

[0125]

[0126] When the power coupling factor When the power coupling coefficient is positive and its absolute value increases, the stability level of the grid-connected system of the grid-connected converter deteriorates; when the power coupling coefficient is negative and its absolute value increases, the system stability level improves. Therefore, based on the analysis of the power coupling energy change rate, the contribution of the power coupling of the grid-connected converter to the system stability can be quantified.

[0127] In an exemplary embodiment, the power coupling mechanism of the grid-connected system of the grid-connected converter is analyzed based on the energy function model.

[0128] It can be seen from formula (12) and formula (13) that the power coupling energy of the grid-type converter is affected by the stable operation parameters of the system. Therefore, substituting the power expression of the grid-type converter in steady state in formula (3) into formula (12) and formula (13), the power coupling energy expression of the grid-type converter can be obtained:

[0129]

[0130] Among them, P0 and E0 are the initial values ​​of the active power and terminal voltage of the grid-connected converter respectively.

[0131] It can be seen from formula (16) that the power coupling energy is related to the equivalent line resistance of the grid-connected converter. If the line resistance is much smaller than the line reactance in a high-voltage long-distance transmission line, the power coupling of the grid-connected converter will have a positive damping effect on the system stability. If the power coupling effect caused by the line resistance is on a low-voltage short-distance transmission line, it is difficult to ignore it, so its impact needs to be analyzed in detail.

[0132] Therefore, according to the power coupling mechanism of the grid-type converter, the energy interaction path between the active control loop and the reactive control loop in the grid-type converter is determined, including: obtaining the interactive energy expression of the power coupling of the grid-type converter; determining the oscillation phase correlation relationship between the phase angle output by the active control loop and the voltage output by the reactive control loop according to the small signal models of the active control loop and the reactive control loop; analyzing the interactive energy expression and the oscillation phase correlation relationship, and determining that the energy interaction path is the energy interaction path transmitted from the active control loop to the reactive control loop.

[0133] When the system is disturbed and an oscillation mode of α+jωc is induced, the general formulas of the oscillation components in the terminal voltage, phase angle and speed are ΔE=AEeαtcos(ωct+θE), Δω=Aωeαtcos(ωct+θω) and Δθ=Aθeαtcos(ωct+θθ), respectively. Substituting them into formula (16), we can solve We can get:

[0134]

[0135] In the formula, and The positive and negative of is mainly affected by the oscillation phase of the voltage and phase angle.

[0136] According to the small signal model of the active control loop and the reactive control loop, the oscillation phase correlation relationship between the phase angle output by the active control loop and the voltage output by the reactive control loop is determined, specifically including: combining formula (4) and formula (5) to solve and The transfer function between ΔE and Δθ is:

[0137] ΔE(s)=G θ-E (s)Δθ(s) (18)

[0138] in,

[0139]

[0140] From formula (18), the oscillation phase correlation relationship between voltage E and phase angle θ is:

[0141]

[0142] in,

[0143] Combining formula (20) and the inverse tangent function graph, we can see that the lead-lag relationship between the voltage and phase angle oscillation phase depends on the coefficient positive and negative.

[0144] when When When the voltage and phase angle oscillation phase difference and like Figure 3 At this time Combining formula (17) we can get:

[0145]

[0146] From formula (20), we can see that the rate of change of the interactive energy transferred from the reactive power control loop to the active power control loop is And the rate of change of the interactive energy transferred from the active control loop to the reactive control loop Both are positive, which helps to increase the storage energy accumulation and presents a negative damping contribution to the system. At this time, the active-reactive coupling of the grid-connected converter is very likely to induce system oscillation instability.

[0147] when When When the voltage and phase angle oscillation phase difference and like Figure 4 At this time Combined with formula (17), it can be seen that the positive and negative power coupling energy can be expressed as:

[0148]

[0149] In formula (21), the rate of change of the interactive energy transferred from the reactive power control loop to the active power control loop is It is always negative, which helps to speed up the reduction of stored energy and is conducive to system stability, but the rate of change of the interactive energy transferred from the active control loop to the reactive control loop A positive value helps to increase the energy accumulation of the system, which is not conducive to the stability of the system. The value is greater than Therefore, the rate of change of the interactive energy generated by active-reactive coupling is generally negative, which is conducive to the rapid dissipation of energy and presents a positive damping effect on the system.

[0150] Based on the above analysis, it can be known that the energy interaction path may include transmitting the angular frequency output by the active control loop to the reactive control loop, and the energy feedback branch is used to adjust the output of the reactive control loop according to the angular frequency output by the active control loop.

[0151] Moreover, the interactive energy transferred from the active control loop to the reactive control loop is the key interactive link that causes the system oscillation divergence, and its instability boundary condition is mainly affected by the line admittance parameter g1 and the steady-state equilibrium point of the grid-connected converter. The impact of The steady-state equilibrium point can be approximated is equivalent to g0, where g0 is the equivalent internal conductance of the grid-type converter. Therefore, the stable boundary condition of the grid-type converter in the low-voltage short-distance power transmission system can be expressed as:

[0152] When g1>g0, that is, when the grid-connected system line conductance g1 of the grid-connected converter is greater than the equivalent internal conductance g0 of the converter, the active-reactive coupling exhibits a negative damping effect, which is not conducive to system stability.

[0153] When g1<g0, that is, when the grid-connected system line conductance g1 of the grid-connected converter is less than the equivalent internal conductance g0 of the converter, the active-reactive coupling exhibits a positive damping effect, which is beneficial to the stability of the system.

[0154] S102, construct an energy feedback branch according to the energy interaction path; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive control loop.

[0155] Analogous to the traditional feedback control structure, the stored energy of the reactive subsystem is regarded as the controlled object, and the interactive energy transmitted from the active control loop to the reactive control loop is regarded as the feedback object. An energy feedback branch is constructed on the reactive-voltage control loop for active damping control to eliminate the negative dissipation effect of the reactive control loop on the stored energy. In this way, the entire system is stable in the sense of Lyapunov, the rate of change of stored energy is negative under any circumstances, and the system oscillation gradually tends to a stable state. The energy feedback model structure is as follows: Figure 5 shown.

[0156] The interactive energy transferred from the active control loop to the reactive control loop is generated in the process of transferring the state variable θ (angle) to the state variable E. Its energy change rate Therefore, in order to suppress its negative damping effect, it is necessary to introduce a compensation function of θ-E in the compensation branch to generate a positive additional damping feedback channel between the active and reactive control loops. The compensation function dE is designed as:

[0157]

[0158] like Figure 6 As shown, Figure 61 is a structural diagram of an energy feedback branch, wherein the energy feedback branch 100 comprises a numerical square module 101, a multiplication gain module 102, a subtractor 103, a scaling module 104, a multiplier 105 and an integration unit 106; the input end of the numerical square module 101 inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module 101 is connected to the positive input end of the subtractor 103 through the multiplication gain module 102, the negative input end of the subtractor 103 inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor 103 is connected to the first input end of the multiplier 105 through the scaling module 104, the second input end of the multiplier 105 is connected to the output end of the integration unit 106, the input end of the integration unit 106 is connected to the angular frequency output end of the active control loop, and the output end of the multiplier 105 is connected to the reactive power input end of the reactive control loop.

[0159] After the energy feedback branch is introduced, the small signal model of the reactive-voltage control loop is:

[0160]

[0161] in,

[0162] The energy feedback branch expression is:

[0163]

[0164] Among them, V t,c It is the compensation energy term generated by the feedback energy branch.

[0165] Combining formulas (3), (4) and (24), it can be obtained that after adding the energy feedback branch, the non-periodic component of the system power coupling energy derivative is:

[0166]

[0167] After the energy feedback branch is introduced, the oscillation phase difference of voltage and phase angle in formula (25) is It can be expressed as:

[0168]

[0169] At this time, the oscillation phase difference between the voltage and the phase angle is depending on positive and negative.

[0170] when Always holds true, that is, when the energy feedback branch coefficient A>1, From formula (25), we can know and are all negative values. At this time, the power coupling of the grid-type converter presents a positive damping effect as a whole, which is beneficial to the stability of the system.

[0171] S103, compensating for the negative damping effect caused by the power coupling between the active control loop and the reactive control loop according to the energy feedback branch, so as to realize the control of active damping of power oscillation of the grid-connected converter.

[0172] like Figure 7 As shown, the compensation function in the energy feedback branch is:

[0173]

[0174] Among them, P1 represents the compensation power, E0 represents the rated output voltage, g1 represents the equivalent line resistance, P0 represents the rated active power, A represents the deviation coefficient, ω represents the angular frequency, and θ represents the phase angle.

[0175] Therefore, according to the energy feedback branch, the negative damping effect generated by the power coupling between the active control loop and the reactive control loop is compensated to realize the control of active damping of power oscillation of the grid-type converter, including: squaring the rated output voltage E0 of the grid-type converter through a numerical square module, and multiplying the squared rated output voltage with the equivalent line resistance g1 through a multiplication gain module to obtain a first power; calculating the difference between the first power and the rated active power P0 of the grid-type converter through a subtractor to obtain a first power deviation; multiplying the first power deviation with a preset deviation coefficient A through a scaling module to obtain a second power deviation; integrating the angular frequency ω output by the active control loop through an integration unit to obtain a phase angle θ; multiplying the phase angle with the second power deviation through a multiplier to obtain the compensation power P1 generated by the energy feedback branch, generating a voltage through the compensation power and the energy value output by the reactive control loop, and generating a pulse width modulation signal according to the voltage and the phase angle output by the active control loop to realize the control of active damping of power oscillation of the grid-type converter.

[0176] In an exemplary embodiment, the basic response capability of the grid-connected converter after the introduction of the energy feedback path may also be analyzed to explore the compatibility of the control strategy.

[0177] Taking power step as an example, the basic response characteristics of grid-connected converter are studied. After the energy feedback branch is introduced, the grid-connected system input ΔP ref The transfer function relationship between the output ΔP is as follows Figure 8 shown.

[0178] From formulas (1), (3) and (23), we can get Figure 8 The three transfer function expressions are:

[0179]

[0180] Combined with formula (28), after introducing the energy feedback branch, the expression of the power step open-loop transfer function G0(s) of the grid-connected converter is:

[0181]

[0182] For ease of analysis, the above formula is simplified to:

[0183]

[0184] Among them, the expressions of coefficients C, D, M and N are:

[0185]

[0186] From formula (30), we can see that after the energy feedback branch is introduced, the system input ΔP ref The transfer function G0(s) between the output ΔP is a second-order system. Under the action of the unit step output, the steady-state error of the system e(∞) = 0, and the system is a zero-difference system. Therefore, after the introduction of the energy feedback branch, the output power of the grid-type converter can still accurately track the power regulation command when a power step occurs, maintaining the stable operation of the system.

[0187] In an exemplary embodiment, in order to verify the feasibility of the control method of the present invention, the main parameters of the grid-connected system of the grid-connected converter are shown in Table 1. By setting different divergence and oscillation scenarios, the accuracy of the energy model and the power coupling mechanism are verified, and the oscillation scenarios before and after the introduction of the control strategy are compared to verify the effectiveness of the control strategy.

[0188] Table 1

[0189] parameter Numeric parameter Numeric <![CDATA[Phase voltage amplitude V g > 220V <![CDATA[Filter inductor L f > 50uH <![CDATA[Rated frequency ω0 of the power grid]]> 100π <![CDATA[Filter capacitor C f > 50uF <![CDATA[Rated active power P0]]> 15kW <![CDATA[Rated output voltage E0]]> 311V Virtual inertia J 20 <![CDATA[Rated reactive power Q0]]> 0Var <![CDATA[Damping coefficient D p > 200 Voltage integration coefficient K 200 Current loop parameters 0.1 / 50 <![CDATA[Drooping coefficient D q > 200 Voltage loop parameters 40 / 10 <![CDATA[Voltage reference value V B > 220V

[0190] By adjusting the grid conductivity parameters to stimulate oscillation divergence and convergence, such as Fig. 9 and Fig.10 Formulas (12) and (13) are used to calculate the storage energy, interaction energy, and dissipated energy trends in the two scenarios to verify the accuracy of the energy model.

[0191] For oscillation convergence conditions, Fig.11a , Fig.11b and Fig.11c The interaction energy V under the oscillation convergence condition is given respectively t , dissipated energy V d and stored energy V s The changing trajectory of the grid-type converter is shown in the figure. The horizontal axis is the change of the output phase angle Δθ of the grid-type converter, the vertical axis is the change of the output voltage ΔE of the grid-type converter, and the z-axis is the calculation result of the energy. Fig.11a V t The changing trajectory under the oscillation convergence condition, Fig.11b V d The changing trajectory under the oscillation convergence condition, Fig.11c V s The change trajectory under the oscillation convergence condition. For the change trajectory of all the above energy terms, point A is the starting point of the trajectory and point B is the end point of the trajectory.

[0192] Depend on Fig.11a , Fig.11b and Fig.11c It can be seen that the stored energy V s Equal to the interaction energy V t , dissipated energy V d The sum of , and both show a decreasing trend over time. Combined with Lyapunov's second stability criterion, it can be obtained that the energy conservative system is in an oscillating stable state at this time, which is consistent with Fig. 9 The experimental results of the oscillation convergence are consistent with those of the conventional energy analysis model, which verifies the accuracy of the energy analysis model proposed in this invention.

[0193] For oscillation divergence conditions, Fig.12a , Figure 12b and Fig.12c The interaction energy V under oscillation divergence condition is given t , dissipated energy V d and stored energy V s The changing trajectory of the grid-type converter is shown in the figure. The horizontal axis is the change of the output phase angle Δθ of the grid-type converter, the vertical axis is the change of the output voltage ΔE of the grid-type converter, and the z-axis is the calculation result of the energy. Fig.12a V t The changing trajectory under the oscillation divergence condition, Figure 12b V d The changing trajectory under the oscillation divergence condition, Fig.12c V s The change trajectory under the oscillating divergence condition. For the change trajectory of all the above energy items, point A is the starting point of the trajectory and point B is the end point of the trajectory.

[0194] like Fig.12a , Figure 12b and Fig.12c It can be seen that the stored energy V s It shows a trend of increasing with time. Combined with Lyapunov's second stability criterion, it can be obtained that the energy conservative system is in an oscillating unstable state at this time, and the energy will continue to accumulate over time, which is consistent with Fig.10 This is consistent with the experimental results of oscillation divergence.

[0195] contrast Fig.11b and Figure 12b It can be seen that the dissipated energy V dIt always shows a decreasing trend over time, which is conducive to the rapid dissipation of energy. However, the change trend of interactive energy is different in different scenarios. Fig.12a It can be seen that V t It shows an increasing trend over time, which will help increase energy accumulation. Therefore, the interaction energy is the key factor that causes the system oscillation and instability. The simulation results are consistent with the analysis results.

[0196] In summary, by comparing the changing trajectories of the experimental waveforms and the energy calculation results, it can be seen that the dynamic energy model proposed in the present invention can be used to accurately judge the system stability, and in the grid-connected system of the grid-connected converter, the interactive energy between the power control links is the key factor affecting the system stability.

[0197] Substitute different grid scenario parameters into formula (11) to calculate the power coupling coefficient under different conductance parameter scenarios, such as Fig.13 shown.

[0198] Depend on Fig.13 It can be seen that as the line conductance g1 gradually decreases, the power coupling coefficient of the grid-connected system Its value changes from positive to negative, and at this time g0=0.5, when g1>g0, Active-reactive coupling exhibits negative damping, which is not conducive to system stability. When g1<g0, The active-reactive coupling exhibits a positive damping effect, which is beneficial to system stability.

[0199] Furthermore, different power grid scenarios are set up for simulation to verify the accuracy of the above energy analysis. Fig.13 The scene parameters of point A (g = 0.35mS), point B (g = 0.43mS), point C (g = 0.58mS) and point D (g = 0.68mS) were simulated and verified. The results are as follows Fig.13 shown.

[0200] Depend on Fig.14 It can be seen that at 0.75s, the line parameters are switched from point A to point B, and the oscillation convergence speed slows down. At 2s, the line parameters are switched from point B to point C, g1 changes from less than g0 to greater than g0, and the system oscillation changes from convergence to divergence. At 2.5s, the line parameters are switched from point C to point D, and the oscillation divergence trend intensifies. This analysis result is consistent with Fig.13 The results are consistent with those of the previous paper, which verifies the correctness of the analysis of the power coupling oscillation mechanism of the grid-connected converter by the present invention.

[0201] Fig.15 and Fig.16 The interaction energy V transferred from the active control loop to the reactive control loop under the oscillation convergence and oscillation divergence conditions is given respectively. t,qp The interactive energy V transferred from the reactive power control loop to the active power control loop t,pq's changing trajectory.

[0202] Depend on Fig.15 It can be seen from Figures (a) and (b) in Figure 1 that when the grid-connected system of the grid-connected converter is in the oscillation convergence condition, the interactive energy V transferred from the active control loop to the reactive control loop t,qp As time goes by, its energy change rate is negative, showing a positive damping effect on system oscillation. The interactive energy V transferred from the reactive control loop to the active control loop t,pq As time goes by, the energy accumulation increases, which has a negative damping effect on the system oscillation and is a potential instability interaction path. t,qp The magnitude is much greater than V t,pq , V t,pq The negative dissipation effect can be seen by V t,qp The power coupling effect presents a positive damping effect as a whole.

[0203] Depend on Fig.16 It can be seen from Figures (a) and (b) in Figure 1 that when the grid-connected system of the grid-connected converter is in an oscillation divergence condition, the change rate of the interactive energy transferred from the active control loop to the reactive control loop is and the rate of change of the interactive energy transferred from the reactive power control loop to the active power control loop are all positive values, and The value is much greater than It plays a leading role in the energy interaction process, helps to increase energy accumulation, and has a negative damping effect on system oscillation. Therefore, the active and reactive interaction energy in the reactive control loop is the key interaction link that causes the system oscillation divergence.

[0204] Fig.17 The variation law of system power coupling coefficient with line conductance parameters after the introduction of energy feedback branch is depicted. Fig.13 By comparison, it can be seen that after the energy feedback branch is introduced, the system power coupling coefficient is always less than zero, and the coupling of the active and reactive control loops exhibits a positive damping effect as a whole.

[0205] Further, Fig.13 The simulation verification is carried out by taking the two oscillation scenarios of midpoint C (g = 0.58mS) and point D (g = 0.68mS) as examples. The energy feedback branch is connected at 1s, and the output power waveform of the converter before and after the introduction of the energy feedback branch is compared. Fig.18 shown.

[0206] Depend on Fig.18 It can be seen that after the introduction of the energy feedback branch, the grid-connected system of the grid-connected converter can quickly converge to stability, and has an active damping suppression effect under different line parameter conditions.

[0207] The compatibility of the control strategy proposed in the present invention with the basic response characteristics of the grid-type converter is further verified. A power step is set at 2s, and the response curve of the grid-type converter with the energy feedback branch is as follows: Fig.17 shown.

[0208] Depend on Fig.19 It can be seen that when the power suddenly changes from 1.5kW to 1kW, the power step response characteristics of the grid-type converter remain basically the same before and after the introduction of the energy feedback branch. The grid-type converter can still quickly track the power response requirements, and the introduced energy feedback branch will not affect the basic response characteristics of the converter.

[0209] The control method for active damping of power oscillations of a grid-type converter provided in the present invention can achieve effective suppression of oscillations while taking into account the basic response characteristics. First, a dynamic energy model of the grid-connected system of a grid-type converter taking into account the resistance of low-voltage short-distance lines is constructed, and the energy interaction path of the active and reactive control loops is quantitatively analyzed. On this basis, the key interaction paths that affect the stability of the system are screened, and the influence mechanism of power coupling on the stability of the system is explained. Finally, an energy feedback branch is constructed in the key interaction path to compensate for the negative damping effect caused by power coupling, and the influence of the branch on the basic response characteristics of the converter is verified, and finally a damping control method is constructed that takes into account the basic response characteristics while achieving effective suppression of oscillations.

[0210] The above is a control method for active damping of power oscillation of a grid-type converter provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding control device for active damping of power oscillation of a grid-type converter, such as Fig. 20 shown.

[0211] Fig. 20 A schematic diagram of a control device for active damping of power oscillation of a grid-connected converter provided by the present invention, the device 2000 comprises:

[0212] A determination module 1901 is used to determine an energy interaction path between an active control loop and a reactive control loop in a grid-type converter according to a power coupling mechanism of the grid-type converter;

[0213] The construction module 2002 is used to construct an energy feedback branch according to the energy interaction path; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive control loop;

[0214] The control module 2003 is used to compensate the negative damping effect caused by the power coupling between the active control loop and the reactive control loop according to the energy feedback branch, so as to realize the control of the active damping of the power oscillation of the grid-connected converter.

[0215] For the specific definition of the control device for active damping of power oscillations of a grid-type converter, please refer to the definition of the control method for active damping of power oscillations of a grid-type converter mentioned above, which will not be repeated here. Each module in the above-mentioned control device for active damping of power oscillations of a grid-type converter can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0216] The present invention also provides a computer-readable storage medium, which stores a computer program, which can be used to execute the above Figure 1 A control method for active damping of power oscillations in a grid-connected converter is provided.

[0217] The present invention also provides Fig.21 The structural diagram of the computer device shown in FIG. Fig.21 As shown in the figure, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 A control method for active damping of power oscillations in a grid-connected converter is provided.

[0218] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0219] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present invention.

Claims

1. A control method for active damping of power oscillations in a grid-connected converter, characterized in that: include: According to the power coupling mechanism of the grid-type converter, an energy interaction path between an active control loop and a reactive control loop in the grid-type converter is determined; According to the energy interaction path, an energy feedback branch is constructed; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active power control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive power control loop; According to the energy feedback branch, the negative damping effect generated by the power coupling between the active control loop and the reactive control loop is compensated to realize the control of active damping of the power oscillation of the grid-connected converter.

2. The method according to claim 1, characterized in that The step of determining the energy interaction path between the active control loop and the reactive control loop in the grid-type converter according to the power coupling mechanism of the grid-type converter comprises: According to the power coupling mechanism of the grid-type converter, an interactive energy expression of the power coupling of the grid-type converter is obtained; Determine, according to the small signal models of the active control loop and the reactive control loop, an oscillation phase correlation relationship between the phase angle output by the active control loop and the voltage output by the reactive control loop; The correlation between the interaction energy expression and the oscillation phase is analyzed to determine that the energy interaction path is an energy interaction path transmitted from the active control loop to the reactive control loop.

3. The method according to claim 2, characterized in that The energy interaction path includes transmitting the angular frequency output by the active control loop to the reactive control loop, and the energy feedback branch is used to adjust the output of the reactive control loop according to the angular frequency output by the active control loop.

4. The method according to claim 1, characterized in that The process of determining the power coupling mechanism of the grid-connected converter includes: Performing time derivation on the dynamic energy model of the active control loop and the reactive control loop to determine the time derivative of the dynamic energy model; According to the derivative of the dynamic energy model with respect to time, the influencing factors of determining that the power coupling mechanism is the damping level of the grid-connected converter include the rate of change of the interactive energy generated by the power coupling between the active control loop and the reactive control loop.

5. The method according to claim 4, characterized in that The dynamic energy model of the active control loop is: Among them, V p Represents the energy function of the active control loop, V s,p is the stored energy of the active control loop, V d,p is the dissipated energy of the active control loop, V t,pq is the interactive energy transferred from the reactive control loop to the active control loop, J is the virtual inertia, ω is the angular frequency, E0 is the rated output voltage, V g0 is the infinite system rated voltage, g1 is the equivalent line resistance, θ0 is the initial phase angle, θ is the phase angle of the active control loop output, D p is the damping coefficient. The dynamic energy model of the reactive power control loop is: Among them, V q Represents the energy function of the reactive power control loop, V s,q is the stored energy of the reactive power control loop, V d,q is the dissipated energy of the reactive power control loop, V t,qp is the interactive energy transferred from the active control loop to the reactive control loop, K is the voltage integral coefficient, b1 is the line equivalent susceptance, V g is infinite system voltage.

6. The method according to claim 1, characterized in that The method of compensating the negative damping effect generated by the power coupling between the active control loop and the reactive control loop according to the energy feedback branch to realize the control of active damping of the power oscillation of the grid-connected converter includes: The rated output voltage is squared by the numerical square module, and the squared rated output voltage is multiplied by the equivalent circuit resistance by the multiplication gain module to obtain a first power; Calculating the difference between the first power and the rated active power of the grid-connected converter by the subtractor to obtain a first power deviation; Multiplying the first power deviation by a preset deviation coefficient through the scaling module to obtain a second power deviation; The integrating unit integrates the angular frequency output by the active control loop to obtain a phase angle; multiplying the phase angle and the second power deviation by the multiplier to obtain the compensation power generated by the energy feedback branch; A voltage is generated by the compensation power and the energy value output by the reactive control loop, and a pulse width modulation signal is generated according to the voltage and the phase angle output by the active control loop to achieve control of active damping of power oscillation of the grid-connected converter.

7. A control device for active damping of power oscillations of a grid-connected converter, characterized in that: include: A determination module, used to determine an energy interaction path between an active control loop and a reactive control loop in the grid-type converter according to a power coupling mechanism of the grid-type converter; A construction module, used to construct an energy feedback branch according to the energy interaction path; the energy feedback branch includes a numerical square module, a multiplication gain module, a subtractor, a scaling module, a multiplier and an integration unit; the input end of the numerical square module inputs the rated output voltage of the grid-forming converter, the output end of the numerical square module is connected to the positive input end of the subtractor through the multiplication gain module, the negative input end of the subtractor inputs the equivalent line resistance of the grid-forming converter connected to the power grid, the output end of the subtractor is connected to the first input end of the multiplier through the scaling module, the second input end of the multiplier is connected to the output end of the integration unit, the input end of the integration unit is connected to the angular frequency output end of the active control loop, and the output end of the multiplier is connected to the reactive power input end of the reactive control loop; The control module is used to compensate the negative damping effect generated by the power coupling between the active control loop and the reactive control loop according to the energy feedback branch, so as to realize the control of active damping of power oscillation of the grid-connected converter.

8. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

9. A computer device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method according to any one of claims 1 to 6 is implemented.

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