Method, device and equipment for suppressing multi-strategy wideband oscillation of wind power flexible direct current grid-connected system and medium

Abstract

The present application relates to the technical field of wind power flexible direct current grid-connected system stability control, and particularly relates to a wind power flexible direct current grid-connected system multi-strategy wide frequency band oscillation suppression method, device, equipment and medium, the method comprising: establishing a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wide frequency band oscillation suppression strategies; determining the optimal installation position of the wide frequency band oscillation suppression strategy that meets the phase angle difference margin constraint; selecting an applicable multi-strategy coordinated wide frequency band oscillation suppression strategy combination scheme to improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different operating conditions, ensure that the system obtains suitable stability margins in the target frequency band and the non-target frequency band, and thereby enhance the overall stability of the wind power flexible direct current grid-connected system; the strategy combination method ensures that the wind power flexible direct current grid-connected system has a larger phase angle difference margin in the wide frequency band range, thereby improving the overall stability margin of the system in different frequency bands and guaranteeing the stability and robustness of the wind power flexible direct current grid-connected system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind power flexible direct current grid-connected system stability control, and in particular to a wind power flexible direct current grid-connected system multi-strategy wide-band oscillation suppression method, device, equipment and medium. BACKGROUND

[0002] The wind power flexible direct current grid-connected system is prone to be affected by different frequency band oscillations in actual operation, resulting in reduced system stability. The traditional oscillation suppression strategy generally realizes the oscillation suppression effect of the system by improving the damping of the unstable frequency band. However, due to the coupling relationship between the dampings of different frequency bands, the improvement of the damping of the target frequency band may cause the deterioration of the damping of the non-target frequency band, or even lead to system instability. To address this problem, two types of oscillation suppression strategies are currently mainly used: active oscillation suppression strategy and passive oscillation suppression strategy.

[0003] The active oscillation suppression strategy adjusts the system control parameters to change the port external characteristics, thereby improving the damping effect. However, the effect is limited by factors such as control bandwidth and link delay. The passive oscillation suppression strategy relies on hardware devices to reshape the impedance characteristics of the system. However, the parameter adjustment is not flexible enough to adapt to changing operating conditions. In addition, the control bandwidth and deployment location of different strategies are different, resulting in interactive coupling of their control effects. When suppressing oscillation in a specific frequency band, it may trigger oscillation in other frequency bands. For example, in the Yuzhong-Ezhou direct current back-to-back networking project, after using low-pass filtering to suppress the 1810Hz high-frequency oscillation, the high-frequency oscillation is controlled, but the 700Hz medium-frequency oscillation is triggered. This shows that a single oscillation suppression strategy cannot achieve wide-band oscillation suppression for low, medium and high frequencies.

[0004] The existing multi-strategy wide-band oscillation suppression method for wind power flexible direct current grid-connected systems has the following problems: when each strategy suppresses the oscillation of the target frequency band, it is difficult to effectively avoid the excessive reduction of the phase angle difference margin of the non-target frequency band, thereby affecting the overall stability of the system. Therefore, there is an urgent need for a multi-strategy coordination method that can coordinate multiple strategies and provide robust oscillation suppression effect in different frequency band ranges to improve the overall stability of the system.

[0005] The information disclosed in this BACKGROUND section is only intended to enhance the understanding of the general background of the application and should not be taken as an acknowledgment or any form of suggestion that this information forms prior art that is already known to those skilled in the art. SUMMARY

[0006] The present application provides a wind power flexible direct current grid-connected system multi-strategy wide-band oscillation suppression method, device, equipment and medium, thereby effectively solving the problems in the background art.

[0007] In order to achieve the above object, the technical scheme adopted by the present application is: a multi-strategy wideband oscillation suppression method for a wind power flexible direct current grid-connected system, comprising the following steps:

[0008] A harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wideband oscillation suppression strategies is established, the impedance characteristics of each wideband oscillation suppression strategy in different frequency bands are analyzed, and the frequency band response behavior of the system in different frequency band ranges is obtained;

[0009] Based on the harmonic state space impedance model, the phase angle difference margin of the non-target frequency band and the target frequency band under different installation positions is calculated, and the optimal installation position of the wideband oscillation suppression strategy meeting the phase angle difference margin constraint is determined, so as to ensure that the phase angle difference margin of the non-target frequency band is not lower than a preset threshold;

[0010] Based on the optimal installation position, the effect of each wideband oscillation suppression strategy is analyzed for different operating conditions, and a suitable multi-strategy coordinated wideband oscillation suppression strategy combination scheme is selected, so as to improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different conditions, ensure that the system obtains suitable stability margin in the target frequency band and the non-target frequency band, and thus enhance the overall stability of the wind power flexible direct current grid-connected system.

[0011] Further, the harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wideband oscillation suppression strategies is established, and the steps include:

[0012] A single wideband state space model of the wind power flexible direct current grid-connected system and a single wideband oscillation suppression strategy is established;

[0013] Based on the single wideband state space model, the influence of different wideband oscillation suppression strategies on the dynamic response of the system under different installation positions is analyzed, a state space model of different widebands and different installation positions is established, and the influence of different installation positions on the dynamic response of the system is analyzed;

[0014] Based on the state space model of different widebands and different installation positions, a linearized state space model of the wind power flexible direct current grid-connected system is established, so as to simplify the dynamic characteristics of the system and facilitate subsequent analysis;

[0015] Based on the linearized state space model, a harmonic linearized state space model of the wind power flexible direct current grid-connected system is established, and the influence of each order harmonic on the stability of the system is analyzed;

[0016] Based on the harmonic linearized state space model, a harmonic linearized state space impedance model of the wind power flexible direct current grid-connected system is established, which is used to describe the impedance response of the system to different frequency band oscillations, and provides a basis for the implementation of subsequent optimization strategies.

[0017] Further, the single wideband state space model comprises:

[0018]

[0019] where d denotes differential, x act_i is the state variable of the i-th wide-band oscillation suppression strategy, t is time, A act_i is the state matrix of the i-th wide-band oscillation suppression strategy, B act_i is the input matrix of the i-th wide-band oscillation suppression strategy, u act_i is the input variable of the i-th wide-band oscillation suppression strategy.

[0020] Further, the state space model of different installation positions is established, comprising:

[0021]

[0022] where x sysact_i-w,c,v is the state variable of the i-th wide-band oscillation suppression strategy respectively installed in the wind turbine converter, the bus, and the flexible AC transmission system (FACTS) converter, A sysact_i-w,c,v is the state matrix of the i-th wide-band oscillation suppression strategy respectively installed in the wind turbine converter, the bus, and the FACTS converter, B sysact_i-w,c,v is the input matrix of the i-th wide-band oscillation suppression strategy respectively installed in the wind turbine converter, the bus, and the FACTS converter, u sysact_i-w,c,v is the input variable of the i-th wide-band oscillation suppression strategy respectively installed in the wind turbine converter, the bus, and the FACTS converter.

[0023] Further, the linearized state space model of the wind power flexible AC transmission system is established, comprising:

[0024]

[0025] where A sysact_i-w,c,v is the state matrix of the i-th wide-band oscillation suppression strategy respectively installed in the wind turbine converter, the bus, and the FACTS converter, Δx sysact_i-w,c,v represents the increment of x sysact_i-w,c,v .

[0026] Further, the harmonic linearized state space model of the wind power flexible AC transmission system is established, comprising:

[0027] sΔX sysact_i-w,c,v = (A Tsysact_i-w,c,v -N)ΔX sysact_i-w,c,v ;

[0028] where s is the Laplace operator, ΔX sysact_i-w,c,vA represents a vector of each order harmonic after the broadband oscillation suppression strategy is added Tsysact_i-w,c,v A is a toplez matrix for frequency domain convolution calculation after the broadband oscillation suppression strategy is added, and N is a diagonal matrix reflecting frequency information.

[0029] Further, a harmonic linearization state space impedance model of the wind power flexible direct current grid-connected system is established, including:

[0030] Based on the harmonic linearization state space model of the wind power flexible direct current grid-connected system, the flexible harmonic linearization state space impedance and the wind turbine harmonic linearization state space impedance without the broadband oscillation suppression strategy are extracted;

[0031] Based on the harmonic linearization state space model of the wind power flexible direct current grid-connected system, the flexible harmonic linearization state space impedance and the wind turbine harmonic linearization state space impedance with the broadband oscillation suppression strategy are extracted, and the harmonic linearization state space impedance model of the wind power flexible direct current grid-connected system is obtained.

[0032] Further, the phase angle difference margin of the non-target frequency band and the target frequency band under different installation positions is calculated, and the optimal installation position of the broadband oscillation suppression strategy meeting the phase angle difference margin constraint is determined, and the steps include:

[0033] Based on the impedance characteristics of the wind power flexible direct current grid-connected system and the wind turbine, the impedance amplitude-phase diagram without the broadband oscillation suppression strategy and the impedance amplitude-phase diagram with the broadband oscillation suppression strategy are obtained to determine the frequency response characteristics of the system in the low frequency band, the medium frequency band and the high frequency band;

[0034] In the impedance amplitude-phase diagram, the amplitude intersection point of the flexible direct current converter and the wind turbine impedance curve is identified, the phase angle difference without the broadband oscillation suppression strategy is calculated, and 180 degrees is subtracted from the phase angle difference to obtain the initial phase angle difference margin;

[0035] Based on the initial phase angle difference margin, the phase angle difference margin change amount of the low frequency band, the medium frequency band and the high frequency band under the action of different broadband oscillation suppression strategies is calculated respectively to obtain the phase angle difference margin after the broadband oscillation suppression strategy is added;

[0036] Based on the phase angle difference margin after the broadband oscillation suppression strategy is added, the phase angle difference margin change amount of different frequency bands is analyzed; when the phase angle difference margin change amount of a certain frequency band is positive, the frequency band is defined as a target frequency band, and the remaining frequency bands are non-target frequency bands;

[0037] The constraint condition that the broadband oscillation suppression strategy needs to be greater than zero in the non-target frequency band phase angle difference margin, and the constraint condition that the target frequency band phase angle difference margin change amount needs to be not less than a preset value are set;

[0038] respectively, whether the non-target frequency band phase angle difference margin is greater than zero, and whether the target frequency band phase angle difference margin change amount meets the preset value:

[0039] If the non-target frequency band phase angle difference margin is less than zero, or the target frequency band phase angle difference margin change amount is less than the preset value, the installation position of the wide-band oscillation suppression strategy is an unselectable position.

[0040] If the non-target frequency band phase angle difference margin is greater than zero, and the target frequency band phase angle difference margin change amount is greater than or equal to the preset value, the installation position is a selectable position.

[0041] The installation position with the largest target frequency band phase angle difference margin change amount is selected as the optimal installation position of the wide-band oscillation suppression strategy.

[0042] Further, the effects of each wide-band oscillation suppression strategy are analyzed for different operating conditions, and a suitable multi-strategy coordinated wide-band oscillation suppression strategy combination scheme is selected, including the steps of:

[0043] All operating conditions of the wind power flexible DC grid-connected system are set to have the active power output of the wind farm within a preset range.

[0044] For different operating conditions with the active power output of the wind farm within the preset range, it is respectively determined whether the non-target frequency band phase angle difference margin is greater than zero after the wide-band oscillation suppression strategy is added.

[0045] If the non-target frequency band phase angle difference margin is greater than zero under all operating conditions, multi-strategy coordinated suppression is not needed.

[0046] If the non-target frequency band phase angle difference margin is less than zero under an operating condition, multi-strategy coordinated wide-band oscillation suppression is needed.

[0047] When the jth wide-band oscillation suppression strategy is added, if the non-target frequency band phase angle difference margin is negative, k strategies are selected from the m wide-band oscillation suppression strategies to make the non-target frequency band phase angle difference margin increase to a stable value not lower than zero after multi-strategy coordination.

[0048] The non-target frequency band phase angle difference margin change amount before and after the coordination of the k wide-band oscillation suppression strategies and the jth wide-band oscillation suppression strategy is calculated, and when the change amount takes the maximum value, the n combinations of the k wide-band oscillation suppression strategies corresponding to the jth wide-band oscillation suppression strategy after coordination are the selected wide-band oscillation suppression strategy combination scheme.

[0049] Further, the phase angle difference margin variation amount ΔPM of the non-target frequency band before and after the k wide-band oscillation suppression strategies cooperate with the jth wide-band oscillation suppression strategy is calculated sys_marge_n The model of the formula (n=1, 2, k-1) includes:

[0050]

[0051] In the formula, The phase angle difference margin of the non-target frequency band after the n combinations of the k wide-band oscillation suppression strategies are selected and cooperate with the jth wide-band oscillation suppression strategy, and α wvj The phase angle difference margin of the non-target frequency band after the jth wide-band oscillation suppression strategy is added.

[0052] The application also includes a multi-strategy wide-band oscillation suppression device of a wind power flexible direct current grid-connected system, which uses the method as described above, and includes:

[0053] The impedance model establishment module is used to establish a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wide-band oscillation suppression strategies, analyze the impedance characteristics of each wide-band oscillation suppression strategy in different frequency bands, and obtain the frequency band response behavior of the system in different frequency band ranges.

[0054] The installation position calculation module is used to calculate the phase angle difference margin of the non-target frequency band and the target frequency band under different installation positions based on the harmonic state space impedance model, determine the optimal installation position of the wide-band oscillation suppression strategy that meets the phase angle difference margin constraint, and ensure that the phase angle difference margin of the non-target frequency band is not lower than a preset threshold.

[0055] The strategy combination selection module is used to analyze the effect of each wide-band oscillation suppression strategy for different operating conditions based on the optimal installation position, select a suitable multi-strategy cooperative wide-band oscillation suppression strategy combination scheme, improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different operating conditions, ensure that the system obtains appropriate stability margin in the target frequency band and the non-target frequency band, and thus enhance the overall stability of the wind power flexible direct current grid-connected system.

[0056] The application also includes a computer device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the method as described above is realized.

[0057] The application also includes a storage medium, which stores a computer program, and when the processor executes the computer program, the method as described above is realized.

[0058] The application has the following beneficial effects:

[0059] 1.The method for selecting the installation position of a wide-band oscillation suppression strategy is proposed by analyzing the phase angle difference margin variation of different wide-band oscillation suppression strategies at different installation positions (a wind turbine converter, a bus, and a flexible DC converter), considering the non-target frequency band phase angle difference margin constraint and the target frequency band phase angle difference margin variation constraint, and avoiding the situation that the non-target frequency band phase angle difference margin is negative and the system is unstable after a single oscillation suppression strategy is installed under the current working condition.

[0060] 2.The method for selecting a multi-strategy coordinated wide-band oscillation robust suppression strategy combination of a wind power flexible DC grid-connected system is proposed by obtaining the phase angle difference margin variation before and after adding different wide-band oscillation suppression strategies under different operating conditions, selecting a multi-strategy coordinated wide-band oscillation suppression strategy combination, and realizing that the wind power flexible DC grid-connected system has a large phase angle difference margin in a wide frequency band, thereby ensuring that the wind power flexible DC grid-connected system has a large stability margin in a wide frequency band. BRIEF DESCRIPTION OF DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0062] Figure 1 The flow chart of the multi-strategy wide-band oscillation suppression method for a wind power flexible DC grid-connected system;

[0063] Figure 2 The structure diagram of the wind power flexible DC grid-connected system;

[0064] Figure 3 The structure diagram of the multi-strategy wide-band oscillation suppression device for a wind power flexible DC grid-connected system;

[0065] Figure 4 The structure diagram of the computer device. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments.

[0067] As shown in Figure 1 A multi-strategy wide-band oscillation suppression method for a wind power flexible DC grid-connected system includes the following steps:

[0068] S10: Establish a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wide-band oscillation suppression strategies, analyze the impedance characteristics of each wide-band oscillation suppression strategy in different frequency bands, and obtain the frequency band response behavior of the system in different frequency band ranges;

[0069] S20: Based on the harmonic state space impedance model, calculate the non-target frequency band and target frequency band phase angle difference margin under different installation positions, determine the optimal installation position of the wide-band oscillation suppression strategy that meets the phase angle difference margin constraint, and ensure that the non-target frequency band phase angle difference margin is not lower than the preset threshold, thereby avoiding system instability due to the decline in non-target frequency band stability;

[0070] S30: Based on the optimal installation position, analyze the effect of each wide-band oscillation suppression strategy for different operating conditions, and select a suitable multi-strategy coordinated wide-band oscillation suppression strategy combination scheme to improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different conditions, and ensure that the system obtains appropriate stability margin in the target frequency band and the non-target frequency band, thereby enhancing the overall stability of the wind power flexible direct current grid-connected system.

[0071] As shown in Figure 2 , the wind power flexible direct current grid-connected system mainly includes: a wind turbine, a power collection line, and a flexible direct current (flexible direct current, for short, flexible) system, and the method is used;

[0072] Considering that the wide-band oscillation suppression strategy may cause the non-target frequency band phase angle difference margin to be negative and the system to be unstable while improving the target frequency band phase angle difference margin of the wind power flexible direct current grid-connected system, a multi-strategy coordinated wide-band oscillation robust suppression strategy for the wind power flexible direct current grid-connected system is proposed, so that any frequency band has an appropriate positive phase angle difference margin after the wide-band oscillation suppression strategy is added, the stability of the wind power flexible direct current grid-connected system is improved from the wide-band range, and the problem of system instability caused by excessive reduction of the non-target frequency band phase angle difference margin is avoided.

[0073] By analyzing the influence of different wide-band oscillation suppression strategies on the phase angle difference margin at different installation positions such as the wind turbine converter, the busbar, and the flexible direct current converter, a wide-band oscillation suppression strategy installation position selection method based on the phase angle difference margin is proposed. When selecting the installation position, the constraint of the non-target frequency band phase angle difference margin and the requirement of the change of the target frequency band phase angle difference margin are fully considered, thereby avoiding the problem of system instability caused by the negative non-target frequency band phase angle difference margin under certain conditions due to a single oscillation suppression strategy.

[0074] By means of multi-strategy cooperation, the change amount of phase angle difference margin before and after adding different wide-band oscillation suppression strategies according to different operating conditions is analyzed, and a suitable multi-strategy cooperative wide-band oscillation suppression strategy combination is selected. The strategy combination method ensures that the wind power flexible direct current grid-connected system has a larger phase angle difference margin in a wide-band range, thereby improving the overall stability margin of the system in different frequency bands and ensuring the stability and robustness of the wind power flexible direct current grid-connected system.

[0075] By establishing a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wide-band oscillation suppression strategies, the technical solution can deeply analyze the impedance characteristics and frequency band response behavior of each oscillation suppression strategy in different frequency bands, thereby providing basic data support for subsequent installation position selection. In this way, the system can effectively suppress oscillation in the target frequency band while ensuring that the phase angle difference margin in the non-target frequency band meets the stability requirement, thereby avoiding the system instability problem caused by a single suppression strategy in some frequency bands in the background technology.

[0076] By calculating the phase angle difference margin in the non-target frequency band and the target frequency band under different installation positions, the optimal wide-band oscillation suppression strategy installation position is determined, and the non-target frequency band phase angle difference margin is not lower than the preset safety threshold, thereby reducing or avoiding the system instability caused by the too low non-target frequency band phase angle difference margin in the background technology. This position optimization strategy effectively solves the problem of deterioration of non-target frequency band damping caused by different frequency band coupling in the background technology, and improves the robustness and operation reliability of the system.

[0077] Under different operating conditions, the scheme can obtain a higher phase angle difference margin in different frequency bands by selecting and combining suitable multi-strategy cooperative wide-band oscillation suppression strategies, thereby effectively improving the overall stability of the system in the wide-band. Compared with the limitation that a single suppression strategy in the background technology cannot cover a wide-band and may excite oscillation in other frequency bands, the present application solves the stability control problem in the wide-band range by multi-strategy cooperation, and ensures that the system obtains sufficient stability margin in each target frequency band and non-target frequency band.

[0078] As a preferred embodiment of the above embodiment, in step S10, a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wide-band oscillation suppression strategies is established, and the step includes:

[0079] S11: Establish a single wide-band oscillation suppression strategy and a single wide-band state space model of the wind power flexible direct current grid-connected system, which is used to represent the influence of the suppression strategy on the frequency response of the system;

[0080] S12: Based on the single wideband state space model, the influence of different wideband oscillation suppression strategies on the dynamic response of the system in different installation positions is analyzed, and state space models of different wideband and different installation positions are established to analyze the influence of different installation positions on the dynamic response of the system;

[0081] S13: Based on the state space models of different wideband and different installation positions, a linearized state space model of the wind power flexible direct current grid-connected system is established to simplify the dynamic characteristics of the system and facilitate subsequent analysis;

[0082] S14: Based on the linearized state space model, a harmonic linearized state space model of the wind power flexible direct current grid-connected system is established to analyze the influence of each order harmonic on the stability of the system;

[0083] S15: Based on the harmonic linearized state space model, a harmonic linearized state space impedance model of the wind power flexible direct current grid-connected system is established to describe the impedance response of the system to different frequency band oscillations, which provides a basis for the implementation of subsequent optimization strategies.

[0084] The finally established harmonic linearized state space impedance model can intuitively describe the impedance response of the system to different frequency band oscillations, provide data support for subsequent strategy optimization, not only improve the suppression effect of the system in the target frequency band, but also effectively avoid the system instability risk caused by the decrease of the non-target frequency band phase angle difference.

[0085] In step S11, the wideband oscillation suppression strategy has m kinds (i=1, 2, …, m), and the single wideband state space model includes:

[0086]

[0087] In the formula, d represents differentiation, x act_i is the state variable of the i-th wideband oscillation suppression strategy, t is time, A act_i is the state matrix of the i-th wideband oscillation suppression strategy, B act_i is the input matrix of the i-th wideband oscillation suppression strategy, u act_i is the input variable of the i-th wideband oscillation suppression strategy.

[0088] Through the single state space model, the influence of the i-th wideband oscillation suppression strategy on the frequency response of the system can be accurately characterized, including the change of the state variable and the action of the external input. Compared with the traditional analysis method, the state space model can clearly describe the dynamic characteristics of the system in mathematical form, which is convenient for analyzing the effect of different strategies.

[0089] Step S12: Based on the single wide-band state space model, the influence of different wide-band oscillation suppression strategies on the dynamic response of the system under different installation positions is analyzed, and the state space models of different wide-band and different installation positions are established to analyze the influence of different installation positions on the dynamic response of the system;

[0090] The interface relationship between the m kinds of wide-band oscillation suppression strategies respectively installed on the wind turbine converter, the bus, the flexible converter and the wind power flexible grid-connected system is established:

[0091]

[0092] The above formula represents the interface relationship between the i-th wide-band oscillation suppression strategy respectively installed on the wind turbine converter, the bus, the flexible converter and the wind power flexible grid-connected system;

[0093] In the formula, the subscript-w of the variable represents that the wide-band oscillation suppression strategy is installed on the wind turbine converter, -c represents that the wide-band oscillation suppression strategy is installed on the bus, and -v represents that the wide-band oscillation suppression strategy is installed on the flexible converter;

[0094] U act_i-w,c,v is the voltage variable of the i-th wide-band oscillation suppression strategy respectively installed on the wind turbine converter, the bus, and the flexible converter, U wv is the voltage variable of the wind power flexible grid-connected system, O actU_i-w,c,v represents the voltage interface variable between the i-th wide-band oscillation suppression strategy respectively installed on the wind turbine converter, the bus, and the flexible converter and the wind power flexible grid-connected system, I act_i-w,c,v is the current variable of the i-th wide-band oscillation suppression strategy respectively installed on the wind turbine converter, the bus, and the flexible converter, I wv is the current variable of the wind power flexible grid-connected system, O actI_i-w,c,v represents the current interface variable between the i-th wide-band oscillation suppression strategy respectively installed on the wind turbine converter, the bus, and the flexible converter and the wind power flexible grid-connected system; ψ act_i-w,c,v represents the coordinate system of the i-th wide-band oscillation suppression strategy installed on the wind turbine converter, the bus, and the flexible converter, ψ wv is the coordinate system of the wind power flexible grid-connected system, R act_i-w,c,v represents the interface variable between the coordinate system of the i-th wide-band oscillation suppression strategy installed on the wind turbine converter, the bus, and the flexible converter and the coordinate system of the wind power flexible grid-connected system.

[0095] In this embodiment, in step S12, the state space model of different installation positions is established, including:

[0096]

[0097] wherein x sysact_i-w,c,v is the state variable of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is installed in the wind turbine converter, the bus, and the HVDC converter, respectively, A sysact_i-w,c,v is the state matrix of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is installed in the wind turbine converter, the bus, and the HVDC converter, respectively, B sysact_i-w,c,v is the input matrix of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is installed in the wind turbine converter, the bus, and the HVDC converter, respectively, u sysact_i-w,c,v is the input variable of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is installed in the wind turbine converter, the bus, and the HVDC converter, respectively.

[0098] By establishing separate state space models at different installation positions such as the wind turbine converter, the bus, and the HVDC converter, the influence of the installation position on the dynamic response of the wind power flexible HVDC grid system can be accurately described, and the effect of each wide-band oscillation suppression strategy at different positions can be more carefully analyzed to provide more accurate frequency band response characteristics.

[0099] Step S13: Based on the state space models of different wide bands and different installation positions, a linearized state space model of the wind power flexible HVDC grid system is established to simplify the dynamic characteristics of the system and facilitate subsequent analysis;

[0100] The state space model of the wind power flexible HVDC grid system includes:

[0101]

[0102] wherein x wv is the state variable of the wind power flexible HVDC grid system, A wv is the state matrix of the wind power flexible HVDC grid system, B wv is the input matrix of the wind power flexible HVDC grid system, u wv is the input variable of the wind power flexible HVDC grid system.

[0103] The above model is linearized to establish a linearized state space model of the wind power flexible HVDC grid system:

[0104]

[0105] wherein Δx represents the increment of x.

[0106] wv wv

[0107] As a preferred embodiment of the above embodiment, in step S13, the state space models of different installation positions are linearized to establish a linear state space model of the wind power flexible HVDC grid-connected system, including:

[0108]

[0109] wherein A sysact_i-w,c,v is the state matrix of the wind power flexible HVDC grid-connected system when the i-th broadband oscillation suppression strategy is respectively installed in the wind turbine converter, the bus, and the HVDC converter, Δx sysact_i-w,c,v represents the increment of x sysact_i-w,c,v .

[0110] By linearizing the state space models of different installation positions, the complex nonlinear dynamic characteristics are simplified into linear models, making the dynamic analysis process of the system more concise and efficient. Linearization significantly reduces the computational complexity, providing a basis for fast calculation for subsequent control optimization, thereby improving the overall system operation efficiency.

[0111] Step S14: Based on the linear state space model, a harmonic linear state space model of the wind power flexible HVDC grid-connected system is established to analyze the influence of each order harmonic on system stability.

[0112] Any periodic time-varying signal can be expressed in the form of Fourier series under the Dirichlet condition; the periodic signal Δu(t) is expressed in the form of Fourier series;

[0113]

[0114] wherein n is the harmonic order, Δu n and θ n (n=0, 1, 2,...) represent the amplitude and initial phase angle of the n-th harmonic, respectively, t is time, and ω1 is the system fundamental frequency angular frequency.

[0115] The periodic signal Δu(t) is transformed using the Euler formula cosθ=0.5(e jθ +e -jθ );

[0116]

[0117] wherein ΔU n is the Fourier coefficient of the n-th harmonic, which is a complex number containing signal amplitude and initial phase angle, and Z is a set of harmonic orders.

[0118] The input variable for linear time-varying model frequency domain analysis is defined as a complex exponential modulated periodic signal.

[0119]

[0120] wherein s is a Laplace operator;

[0121] obtaining state variables and derivatives thereof of the wind power flexible direct current grid-connected system;

[0122]

[0123] wherein j is an imaginary unit; e st is a complex exponential signal of the wind power flexible direct current grid-connected system, x wv (t) is a function of time of the state variable of the wind power flexible direct current grid-connected system, Δx wv (t) represents an increment of x wv (t); is a derivative of Δx wv (t) with respect to time, x n is a state variable under n-th harmonic, Δx n represents an increment of x n ;

[0124] The above expression is transformed into:

[0125]

[0126] wherein is a form of Fourier series expansion of A under n-th harmonic;

[0127] wv

[0128] The above formula describes a relationship between Fourier coefficients of state variables, input variables and output variables, and is inconvenient for analysis and calculation due to containing convolution operation; in order to facilitate calculation, a Toeplitz matrix is introduced;

[0129]

[0130] wherein A T is a Toeplitz matrix for frequency domain convolution calculation of the wind power flexible direct current grid-connected system, A T the subscript of an element in A

[0131] The state equations of each harmonic are combined and expressed in a form of Toeplitz matrix, and a harmonic linearized state space model of the wind power flexible direct current grid-connected system is obtained;

[0132] sΔX=(A T -N)ΔX;

[0133] wherein ΔX is a vector containing each order harmonic; N is a diagonal matrix reflecting frequency information.

[0134] In the embodiment, in step S14, the harmonic linearized state space model of the wind power flexible direct current grid-connected system is established, including:

[0135] sΔX sysact_i-w,c,v =(A Tsysact_i-w,c,v -N)ΔX sysact_i-w,c,v ;

[0136] wherein s is a Laplacian operator, ΔX sysact_i-w,c,v represents a vector of each order harmonic after adding the wideband oscillation suppression strategy, A Tsysact_i-w,c,v is a Toeplitz matrix for frequency domain convolution calculation after adding the wideband oscillation suppression strategy, and N is a diagonal matrix reflecting frequency information.

[0137] By establishing a harmonic linearization state space model, the vector of each order harmonic is used to describe the response characteristics of the system at different frequency orders after adding the wideband oscillation suppression strategy, which can accurately capture the dynamic changes of the system at each harmonic frequency, so that the frequency characteristics of the system are more comprehensively understood, providing data support for optimizing harmonic suppression.

[0138] In step S14, a harmonic linearization state space impedance model of the wind power flexible direct current grid-connected system is established, including:

[0139] Based on the harmonic linearization state space model of the wind power flexible direct current grid-connected system, the flexible direct current harmonic linearization state space impedance Z mmc and the wind turbine harmonic linearization state space impedance Z pmsg are extracted when the wideband oscillation suppression strategy is not added.

[0140] Based on the harmonic linearization state space model of the wind power flexible direct current grid-connected system, the flexible direct current harmonic linearization state space impedance Z sysact_mmc and the wind turbine harmonic linearization state space impedance Z sysact_pmsg are extracted when the wideband oscillation suppression strategy is added, to obtain the harmonic linearization state space impedance model of the wind power flexible direct current grid-connected system.

[0141] By extracting the harmonic linearization state space impedance of the flexible direct current and the wind turbine in the state of not adding and adding the wideband oscillation suppression strategy, respectively, the impedance change characteristics of the system in different states can be compared, and the differential extraction method effectively reveals the specific influence of the wideband suppression strategy on the harmonic characteristics of the system, providing a scientific comparison basis for subsequent optimization.

[0142] As a preferred embodiment of the above, according to the above content, in step S20, the phase angle difference margin of the non-target frequency band and the target frequency band at different installation positions is calculated to determine the optimal installation position of the wideband oscillation suppression strategy that satisfies the phase angle difference margin constraint, and the step includes:

[0143] S21: Based on the impedance characteristics of the wind power flexible direct current grid-connected system and the wind turbine, impedance amplitude-phase diagrams are obtained when the wide-band oscillation suppression strategy is not added and when the wide-band oscillation suppression strategy is added, so as to determine the frequency response characteristics of the system in the low frequency band, the medium frequency band and the high frequency band;

[0144] S22: In the impedance amplitude-phase diagram, the amplitude intersection point of the impedance curves of the flexible direct current converter and the wind turbine is identified, the phase angle difference when the wide-band oscillation suppression strategy is not added is calculated, and the initial phase angle difference margin is obtained by subtracting 180 degrees from the phase angle difference;

[0145] S23: Based on the initial phase angle difference margin, the phase angle difference margin change amount of the low frequency band, the medium frequency band and the high frequency band is calculated respectively under the action of different wide-band oscillation suppression strategies, and the phase angle difference margin after the wide-band oscillation suppression strategy is added is obtained;

[0146] S24: Based on the phase angle difference margin after the wide-band oscillation suppression strategy is added, the phase angle difference margin change amount of different frequency bands is analyzed; when the phase angle difference margin change amount of a certain frequency band is positive, the frequency band is defined as a target frequency band, and the remaining frequency bands are non-target frequency bands;

[0147] S25: Set the constraint condition that the wide-band oscillation suppression strategy needs to be greater than zero in the non-target frequency band phase angle difference margin, and the constraint condition that the target frequency band phase angle difference margin change amount needs to be not less than a preset value;

[0148] S26: Judge whether the non-target frequency band phase angle difference margin is greater than zero and whether the target frequency band phase angle difference margin change amount meets the preset value under the wide-band oscillation suppression strategy at the positions of the wind turbine converter, the busbar and the flexible direct current converter, respectively:

[0149] If the non-target frequency band phase angle difference margin is less than zero, or the target frequency band phase angle difference margin change amount is less than the preset value, the installation position of the wide-band oscillation suppression strategy is an unselectable position;

[0150] If the non-target frequency band phase angle difference margin is greater than zero, and the target frequency band phase angle difference margin change amount is greater than or equal to the preset value, the installation position is a selectable position;

[0151] S27: Select the installation position with the largest target frequency band phase angle difference margin change amount as the best installation position of the wide-band oscillation suppression strategy.

[0152] Wide-band oscillation suppression strategy added different frequency band phase angle difference margin change amount α sysact_l_i-w,c,v -α wv_l 、α sysact_m_i-w,c,v -α wv_m 、α sysact_h_i-w,c,v -α wv_hThe corresponding frequency band when the phase angle difference margin is positive is the target frequency band of the wide-band oscillation suppression strategy, and the remaining frequency bands are non-target frequency bands. The phase angle difference margin of the non-target frequency band of the wide-band oscillation suppression strategy needs to satisfy the constraint of being greater than 0, and the phase angle difference margin variation of the target frequency band needs to satisfy the constraint of not being less than |Δα act_0 |; the relationship between the phase angle difference margin of the non-target frequency band of the wide-band oscillation suppression strategy and 0, and the relationship between the phase angle difference margin variation of the target frequency band and |Δα act_0 | are respectively judged for the wind power flexible direct-current grid-connected system equipped with a wind turbine converter, a bus, and a flexible direct-current converter. If the phase angle difference margin of the non-target frequency band is less than 0 or the phase angle difference margin variation of the target frequency band is less than |Δα act_0 |, the wide-band oscillation suppression strategy installation position is not selected. If the phase angle difference margin of the non-target frequency band is greater than 0 and the phase angle difference margin variation of the target frequency band is greater than or equal to |Δα act_0 |, the wide-band oscillation suppression strategy installation position is selected, and the wide-band oscillation suppression strategy installation position corresponding to the maximum phase angle difference margin variation of the target frequency band is selected.

[0153] The phase angle difference margin variation of different frequency bands after the wide-band oscillation suppression strategy is added sysact_l_i-w,c,v -α wv_l , α sysact_m_i-w,c,v -α wv_m , α sysact_h_i-w,c,v -α wv_h The corresponding frequency band when the phase angle difference margin is positive is the target frequency band of the wide-band oscillation suppression strategy, and the remaining frequency bands are non-target frequency bands. The phase angle difference margin of the non-target frequency band of the wide-band oscillation suppression strategy needs to satisfy the constraint of being greater than 0, and the phase angle difference margin variation of the target frequency band needs to satisfy the constraint of not being less than |Δα act_0 |; the relationship between the phase angle difference margin of the non-target frequency band of the wide-band oscillation suppression strategy and 0, and the relationship between the phase angle difference margin variation of the target frequency band and |Δα act_0 | are respectively judged for the wind power flexible direct-current grid-connected system equipped with a wind turbine converter, a bus, and a flexible direct-current converter. If the phase angle difference margin of the non-target frequency band is less than 0 or the phase angle difference margin variation of the target frequency band is less than |Δα act_0 |, the wide-band oscillation suppression strategy installation position is not selected. If the phase angle difference margin of the non-target frequency band is greater than 0 and the phase angle difference margin variation of the target frequency band is greater than or equal to |Δα act_0 |, the wide-band oscillation suppression strategy installation position is selected, and the wide-band oscillation suppression strategy installation position corresponding to the maximum phase angle difference margin variation of the target frequency band is selected.

[0154] By calculating the phase angle difference margin of the non-target frequency band and the target frequency band under different installation positions, the most suitable installation position can be accurately selected, so that the wide-band oscillation suppression strategy maximizes the suppression effect in the target frequency band, while ensuring the stability of the non-target frequency band is not negatively affected, thereby improving the overall suppression effect and stability of the system.

[0155] The constraint condition of setting the non-target frequency band phase angle difference margin greater than zero ensures that the stability of the target frequency band is improved without causing instability problems in the non-target frequency band. The constraint condition effectively prevents the frequency band coupling problem that may be caused by a single suppression strategy, which helps to maintain the relative stability of each frequency band of the system.

[0156] By calculating the phase angle difference margin variation of the low frequency band, the medium frequency band and the high frequency band in different frequency bands, this method can specifically identify the target frequency band and the non-target frequency band. The design of frequency band segmentation calculation can adapt to the oscillation suppression requirements in different frequency band ranges, meet the multi-strategy coordination requirements in the wide frequency band range, and enhance the adaptability of the system to multi-band oscillation.

[0157] By calculating the phase angle difference margin variation, the best installation position can be quickly screened out, greatly reducing the trial and error times in the design and debugging process. The optimization method based on mathematical calculation improves the design efficiency of the suppression strategy, making the implementation of the suppression strategy more efficient and effective.

[0158] In this embodiment, in step S30, the effects of each wide-band oscillation suppression strategy are analyzed for different operating conditions, and a suitable multi-strategy coordinated wide-band oscillation suppression strategy combination scheme is selected. The steps include:

[0159] S31: Set all operating conditions of the wind power flexible direct current grid-connected system to the active power output of the wind farm in the preset range P e ={0.1pu, 0.2pu, 0.3pu, 0.4pu, 0.5pu, 0.6pu, 0.7pu, 0.8pu, 0.9pu, 1.0pu}; pu represents the unit value of the output active power;

[0160] S32: For different operating conditions of the wind farm output active power in the preset range, respectively judge whether the non-target frequency band phase angle difference margin is greater than zero after adding the wide-band oscillation suppression strategy;

[0161] If the non-target frequency band phase angle difference margin is greater than zero under all operating conditions, multi-strategy coordination suppression is not needed;

[0162] If the non-target frequency band phase angle difference margin is less than zero under some operating conditions, multi-strategy coordinated wide-band oscillation suppression is needed;

[0163] S33: When the jth (j = 1, 2, …, m) wide-band oscillation suppression strategy is added, if the non-target frequency band phase angle difference margin is negative, then select k strategy combinations (k≤m) from the m wide-band oscillation suppression strategies to make the non-target frequency band phase angle difference margin increase to a stable value not lower than zero after the multi-strategy synergistic effect; wherein the target frequency bands of the k suppression strategies correspond to the non-target frequency bands of the jth suppression strategy;

[0164] S34: Calculate the non-target frequency band phase angle difference margin change amount before and after the k wide-band oscillation suppression strategies and the jth wide-band oscillation suppression strategy synergize, when the change amount takes the maximum value, the n combinations of the k wide-band oscillation suppression strategies corresponding to the jth wide-band oscillation suppression strategy after synergizing are the combination scheme of the selected wide-band oscillation suppression strategies.

[0165] By analyzing the non-target frequency band phase angle difference margin under different operating conditions, it can be determined in real time whether multi-strategy synergistic suppression is needed, thereby improving the stability of the system under different operating conditions. Through accurate analysis of each operating condition, resource waste is avoided when no synergy is needed, and the operating efficiency of the system is effectively improved.

[0166] By calculating and analyzing the phase angle difference margin of the non-target frequency band and the target frequency band, the method can clearly determine the influence of different strategies on a specific frequency band, maximize the effect of each wide-band oscillation suppression strategy, and ensure that the target frequency band is not unstable when suppressing the target frequency band oscillation, thereby avoiding interference between frequency bands.

[0167] When a single strategy cannot meet the stability requirement, the method combines different wide-band oscillation suppression strategies to ensure that the phase angle difference margin of the non-target frequency band reaches a stable state after synergistic effect, which improves the suppression effect of the target frequency band while making the system have a higher stability margin in the wide-band range.

[0168] The method can flexibly switch and synergize between different suppression strategies, adapt to changing operating conditions and harmonic frequency changes, enhance the robustness of the suppression strategy, and achieve higher fault tolerance of the system through multi-strategy combination, so that the wind power flexible AC transmission system can stably operate under various complex conditions.

[0169] In step S34, the non-target frequency band phase angle difference margin change amount ΔPM sys_marge_n (n = 1, 2, k-1) model, including:

[0170]

[0171] In the formula, The non-target frequency band phase angle difference margin after the n combinations of the k wideband oscillation suppression strategies and the jth wideband oscillation suppression strategy are selected and cooperated, alpha wvj The non-target frequency band phase angle difference margin after the jth wideband oscillation suppression strategy is added.

[0172] The change amount of the non-target frequency band phase angle difference margin before and after cooperation is calculated by the formula, which can intuitively quantify the cooperative suppression effect of multiple wideband suppression strategies. The quantitative model provides clear data basis for selecting the optimal strategy combination, so that the effects of different strategy combinations can be directly compared, thereby greatly improving the design efficiency of the suppression strategy.

[0173] The application also includes a multi-strategy wideband oscillation suppression device for a wind power flexible direct current grid-connected system, which uses the method as described above, as shown in the figure, comprising: Figure 3 As shown in the figure, comprising:

[0174] The impedance model establishment module is configured to establish a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different wideband oscillation suppression strategies, analyze the impedance characteristics of each wideband oscillation suppression strategy in different frequency bands, and obtain the frequency band response behavior of the system in different frequency band ranges.

[0175] The installation position calculation module is configured to calculate the non-target frequency band and target frequency band phase angle difference margin under different installation positions based on the harmonic state space impedance model, determine the optimal installation position of the wideband oscillation suppression strategy that meets the phase angle difference margin constraint, and ensure that the non-target frequency band phase angle difference margin is not lower than a preset threshold.

[0176] The strategy combination selection module is configured to analyze the effect of each wideband oscillation suppression strategy for different operating conditions based on the optimal installation position, select a suitable multi-strategy cooperative wideband oscillation suppression strategy combination scheme, and improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different operating conditions, so as to ensure that the system obtains appropriate stability margin in the target frequency band and the non-target frequency band, thereby enhancing the overall stability of the wind power flexible direct current grid-connected system.

[0177] Please refer to Figure 4 The computer device provided by the embodiment of the application includes a processor 410 and a memory 420, the memory 420 stores a computer program executable by the processor 410, and the computer program is executed by the processor 410 to perform the method as above.

[0178] The embodiment of the application also provides a storage medium 430, and the storage medium 430 stores a computer program, and the computer program is executed by the processor 410 to perform the method as above.

[0179] The storage medium 430 can be implemented by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read only memory (EPROM), programmable read only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic or optical disk.

[0180] In the description of the present application, the terms "first", "second", "third", etc. are used only to describe purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. The meaning of "plurality" is two or more, unless otherwise explicitly specified and limited.

[0181] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0182] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0183] Any processes or methods described in the flowcharts or otherwise described herein can be understood as representing modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions or steps, and alternate implementations are possible that include structure that is not shown or described herein, including implementations that use different terminology, structures, or approaches to achieve the same results. The scope of preferred embodiments of the present application includes any implementation that performs the functions described herein, whether explicitly discussed or not.

[0184] Logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be embodied in computer-readable medium, which can be any device or apparatus that can store, communicate, propagate, or transport programming for use by or in connection with an instruction execution system, apparatus, or device. Computer-readable medium can include any suitable medium such as, for example, the following: a portable computer diskette; a hard disk; a system or

[0185] It should be understood that aspects of the present application can be implemented in hardware, software, firmware, or combinations thereof. In the above embodiments, various steps or methods can be implemented in software or firmware that is stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and in another embodiment, any of the following techniques, which are well known in the art, can be used to implement the present application: a hybrid of the above techniques, discrete logic circuit(s) having logic gates for implementing logic functions upon request pins of the data signal, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and / or other implementations which are now known or become known in the future.

[0186] Those skilled in the art can understand that all or part of the steps of the method carried out by the above-mentioned embodiments can be instructed by a program to complete the relevant hardware, and the program can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0187] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments within the scope of the present application.

Claims

1. A method for multi-strategy wide-band oscillation suppression of a wind power flexible direct current grid-connected system, characterized in that, The method comprises the following steps: The method comprises the following steps: The method comprises the following steps: The method comprises the following steps:

2. The multi-strategy wideband oscillation suppression method for a wind power flexible direct current grid-connected system according to claim 1, characterized in that, The method comprises the following steps: The method comprises the following steps: The method comprises the following steps: The method comprises the following steps: The method comprises the following steps: The method comprises the following steps:

3. The multi-strategy wideband oscillation suppression method for a wind power flexible direct current grid-connected system according to claim 2, characterized in that, The method comprises the following steps: where d denotes differentiation, x act_i is a state variable of the i-th wideband oscillation suppression strategy, t is time, A act_i is a state matrix of the i-th wideband oscillation suppression strategy, B act_i is an input matrix of the i-th wideband oscillation suppression strategy, u act_i is an input variable of the i-th wideband oscillation suppression strategy.

4. The multi-strategy wideband oscillation suppression method for a wind power flexible direct current grid-connected system according to claim 2, characterized in that, The method comprises the following steps: In the formula, x sysact_i-w,c,v is the state variable of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is respectively installed in the wind turbine converter, the bus, and the flexible HVDC converter, A sysact_i-w,c,v is the state matrix of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is respectively installed in the wind turbine converter, the bus, and the flexible HVDC converter, B sysact_i-w,c,v is the input matrix of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is respectively installed in the wind turbine converter, the bus, and the flexible HVDC converter, u sysact_i-w,c,v is the input variable of the wind power flexible HVDC grid system when the i-th wide-band oscillation suppression strategy is respectively installed in the wind turbine converter, the bus, and the flexible HVDC converter.

5. The multi-strategy wideband oscillation suppression method for wind power flexible HVDC grid integration system according to claim 2, characterized in that, The method comprises the following steps: In the formula, A sysact_i-w,c,v is the state matrix of the wind power flexible AC-DC grid system when the i-th wide-band oscillation suppression strategy is respectively installed in the wind turbine converter, the bus bar, and the flexible AC-DC converter, Δx sysact_i-w,c,v represents the increment of x sysact_i-w,c,v .

6. The multi-strategy wideband oscillation suppression method for wind power flexible HVDC grid integration system according to claim 2, characterized in that, The method comprises the following steps: sΔX sysact_i-w,c,v = (A Tsysact_i-w,c,v -N)ΔX sysact_i-w,c,v ; where s is Laplacian operator, ΔX sysact_i-w,c,v represents the vector of each order harmonic after adding the wideband oscillation suppression strategy, A Tsysact_i-w,c,v is the Toeplitz matrix for frequency domain convolution calculation after adding the wideband oscillation suppression strategy, and N is a diagonal matrix reflecting frequency information.

7. 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according to claim 1, characterized in that, The phase angle difference margin of the non-target frequency band and the target frequency band in different installation positions is calculated, and the optimal installation position of the wide-band oscillation suppression strategy meeting the phase angle difference margin constraint is determined, and the steps include: Based on the impedance characteristics of the wind power flexible direct current grid-connected system and the wind turbine, the impedance amplitude-phase diagram when the wide-band oscillation suppression strategy is not added and the impedance amplitude-phase diagram when the wide-band oscillation suppression strategy is added are obtained to determine the frequency response characteristics of the system in the low frequency band, the medium frequency band and the high frequency band. In the impedance amplitude-phase diagram, the amplitude intersection point of the flexible direct current converter and the wind turbine impedance curve is identified, the phase angle difference when the wide-band oscillation suppression strategy is not added is calculated, and 180 degrees is subtracted from the phase angle difference to obtain the initial phase angle difference margin. Based on the initial phase angle difference margin, the phase angle difference margin change amount of the low frequency band, the medium frequency band and the high frequency band under the action of different wide-band oscillation suppression strategies is calculated respectively to obtain the phase angle difference margin after the wide-band oscillation suppression strategy is added. Based on the phase angle difference margin after the wide-band oscillation suppression strategy is added, the phase angle difference margin change amount of different frequency bands is analyzed; when the phase angle difference margin change amount of a certain frequency band is positive, the frequency band is defined as a target frequency band, and the remaining frequency bands are non-target frequency bands. The constraint condition that the wide-band oscillation suppression strategy needs to be greater than zero in the non-target frequency band phase angle difference margin and the constraint condition that the target frequency band phase angle difference margin change amount needs to be not less than a preset value are set. Whether the non-target frequency band phase angle difference margin is greater than zero and whether the target frequency band phase angle difference margin change amount meets the preset value are judged respectively under the wide-band oscillation suppression strategy in the wind turbine converter, the bus bar and the flexible direct current converter position. If the non-target frequency band phase angle difference margin is less than zero or the target frequency band phase angle difference margin change amount is less than the preset value, the installation position of the wide-band oscillation suppression strategy is not selectable. If the non-target frequency band phase angle difference margin is greater than zero and the target frequency band phase angle difference margin change amount is greater than or equal to the preset value, the installation position is a selectable position. The installation position with the maximum target frequency band phase angle difference margin change amount is selected as the optimal installation position of the wide-band oscillation suppression strategy. 9.The wind power flexible HVDC grid-connected system multi-strategy wide frequency band oscillation suppression method according to claim 1, characterized in that, The effects of each wide-band oscillation suppression strategy are analyzed for different operating conditions, and a suitable multi-strategy cooperative wide-band oscillation suppression strategy combination scheme is selected, and the steps include: All operating conditions of the wind power flexible direct current grid-connected system are set to be within the preset range of the active power output of the wind farm. For different operating conditions of the wind farm output active power within the preset range, it is judged whether the non-target frequency band phase angle difference margin is greater than zero after the wide-band oscillation suppression strategy is added. If the non-target frequency band phase angle difference margin is greater than zero under all operating conditions, multi-strategy cooperative suppression is not needed. If there is an operating condition under which the non-target frequency band phase angle difference margin is less than zero, multi-strategy cooperative wide-band oscillation suppression is needed. When the jth broadband oscillation suppression strategy is added, if the non-target frequency band phase angle difference margin is negative, k strategy combinations are selected from the m broadband oscillation suppression strategies, so that the non-target frequency band phase angle difference margin is improved to a stable value not lower than zero after the multi-strategy synergistic effect; The change amount of the non-target frequency band phase angle difference margin before and after the k broadband oscillation suppression strategies and the jth broadband oscillation suppression strategy synergize is calculated, and when the change amount takes the maximum value, the n combinations of the k broadband oscillation suppression strategies and the jth broadband oscillation suppression strategy synergize, which is the selected broadband oscillation suppression strategy combination scheme.

10. The multi-strategy wideband oscillation suppression method for a wind power flexible direct current grid-connected system according to claim 9, characterized in that, The non-target frequency band phase margin variation amount ΔPM before and after the kth wideband oscillation suppression strategy and the jth wideband oscillation suppression strategy cooperate sys_marge_n a model of (n = 1, 2, k-1) includes: In the formula, is the non-target frequency band phase angle difference margin after the n combinations of k wideband oscillation suppression strategies are selected and the jth wideband oscillation suppression strategy is cooperated, and α wvj is the non-target frequency band phase angle difference margin after the jth wideband oscillation suppression strategy is added.

11. A wind power flexible direct current grid-connected system multi-strategy wide frequency band oscillation suppression device, characterized in that, The method according to any one of claims 1 to 10 is used, comprising: An impedance model establishing module is configured to establish a harmonic state space impedance model of the wind power flexible direct current grid-connected system under different broadband oscillation suppression strategies, analyze the impedance characteristics of each broadband oscillation suppression strategy in different frequency bands, and obtain the frequency band response behavior of the system in different frequency band ranges; An installation position calculating module is configured to calculate the non-target frequency band and target frequency band phase angle difference margins under different installation positions based on the harmonic state space impedance model, determine the optimal installation position of the broadband oscillation suppression strategy that meets the phase angle difference margin constraint, and ensure that the non-target frequency band phase angle difference margin is not lower than a preset threshold value; A strategy combination selecting module is configured to analyze the effects of each broadband oscillation suppression strategy for different operating conditions based on the optimal installation position, select a suitable multi-strategy synergistic broadband oscillation suppression strategy combination scheme, improve the phase angle difference margin of the wind power flexible direct current grid-connected system under different operating conditions, ensure that the system obtains appropriate stability margins in the target frequency band and the non-target frequency band, and thus enhance the overall stability of the wind power flexible direct current grid-connected system.

12. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the method of any one of claims 1-10.

13. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to implement the method of any one of claims 1-10.

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