Multi-strategy coordinated wideband oscillation uniform suppression method for wind power flexible low-frequency grid-connected system

Abstract

The present invention discloses a method for uniformly suppressing wideband oscillations in a wind power flexible low-frequency grid-connected system using multiple strategies. The method comprises the following steps: 1. establishing a state space model of the wind power flexible low-frequency grid-connected system under different wideband oscillation suppression strategies at different installation locations; 2. obtaining the installation locations of the wideband oscillation suppression strategies under non-target frequency band damping constraints; and 3. selecting the type of multi-strategy coordinated wideband oscillation uniform suppression strategy. The present invention considers the problem that while the wideband oscillation suppression strategy improves the target frequency band damping of the wind power flexible low-frequency grid-connected system, it may also worsen the non-target frequency band damping and cause system instability. The method proposes a multi-strategy coordinated wideband oscillation uniform suppression strategy, which ensures that any frequency band has uniform positive damping after the wideband oscillation suppression strategy is added. This improves the stability margin of the wind power flexible low-frequency grid-connected system from a wide-band range and avoids the problem of system instability caused by the worsening of non-target frequency band damping.

Description

Technical Field

[0001] The present invention belongs to the field of stability control of wind power grid-connected systems, and specifically relates to a multi-strategy coordinated wide-band oscillation uniform suppression strategy for wind power flexible low-frequency grid-connected systems. Background Art

[0002] Oscillation suppression strategies typically suppress oscillations by increasing the damping in the unstable frequency bands of flexible low-frequency grid-connected wind power systems. However, the damping between different frequency bands is coupled. While increasing the damping in the target frequency band may deteriorate the damping in non-target frequency bands, leading to instability. Therefore, a single suppression strategy is unlikely to achieve wide-band oscillation suppression. In the Chongqing-Hubei DC back-to-back interconnection project, low-pass filtering was used to suppress the 1810Hz high-frequency oscillation on the Hubei side, eliminating it. However, at this point, 700Hz medium-frequency oscillations appeared on the Chongqing side. While suppressing a specific frequency band, the single oscillation suppression strategy stimulated oscillations in other frequency bands. The paper "Analysis of High-Frequency Oscillation Characteristics and Suppression Strategies for Flexible DC Transmission Systems" shows that adding a single damping controller is unlikely to improve the stability of flexible low-frequency systems across the entire frequency band. The impedance characteristics of the high-frequency band are sensitive to those of the low-frequency band, resulting in significant coupling between the high- and low-frequency damping. The paper "Impedance Reshaping and Medium- and High-Frequency Oscillation Suppression Method for Flexible DC Transmission" proposes a method for suppressing high-frequency oscillations in a flexible DC transmission system based on a passive impedance reshaper. This method suppresses high-frequency oscillations while preventing the excitation of medium-frequency oscillations. However, the paper does not consider the changes in low-frequency damping during the suppression of medium- and high-frequency oscillations, which could reduce the low-frequency damping and lead to system instability. Flexible low-frequency transmission, as a new AC transmission technology, similar to flexible DC transmission systems, also incorporates power electronic equipment such as AC converters. This leads to wideband dynamic coupling in the control chain, which can cause wideband oscillation problems. Furthermore, compared to DC transmission systems, flexible low-frequency transmission systems exhibit more inter-frequency interaction characteristics, making their dynamic characteristics more complex and the wideband dynamic interaction problem more prominent. Existing suppression strategies employed in research have failed to achieve wideband oscillation suppression (including low-, medium-, and high-frequency bands) in flexible low-frequency grid-connected wind power systems. Summary of the Invention

[0003] The present invention aims to address the deficiencies of the above-mentioned prior art and proposes a multi-strategy coordinated wide-band oscillation uniform suppression strategy for a wind power flexible low-frequency grid-connected system, in order to achieve uniform oscillation suppression in the wide-band (low-band, medium-band, high-band) of the wind power flexible low-frequency grid-connected system by adopting a multi-strategy coordinated approach, so that the wind power flexible low-frequency grid-connected system has approximately equal positive damping in different frequency bands, thereby ensuring that the system has a large stability margin within the wide-band range.

[0004] In order to achieve the above-mentioned object, the present invention adopts the following technical solutions:

[0005] The present invention provides a multi-strategy coordinated broadband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system. The wind power flexible low-frequency grid-connected system mainly includes: a wind turbine generator set, a collector line, and a flexible low-frequency system. The multi-strategy coordinated broadband oscillation uniform suppression method is characterized in that it is performed according to the following steps:

[0006] Step S1: Use equation (1) to establish the state space model of the wind power flexible low-frequency grid-connected system:

[0007] (1)

[0008] In formula (1), represents the differential, x wv is the state variable of the wind power flexible low-frequency grid-connected system, t is time, u wv is the input variable of the wind power flexible low-frequency grid-connected system, A wv is the state matrix of the wind power flexible low-frequency grid-connected system, B wv It is the input matrix of the wind power flexible low-frequency grid-connected system;

[0009] Step S2: Using equations (2) and (3), establish the state space model of the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy respectively:

[0010] (2)

[0011] (3)

[0012] In formula (2), is the state variable of the i-th active broadband oscillation suppression strategy, is the state matrix of the i-th active broadband oscillation suppression strategy, is the input matrix of the i-th active broadband oscillation suppression strategy, is the input variable of the i-th active broadband oscillation suppression strategy; is the state variable of the j-th passive broadband oscillation suppression strategy, is the state matrix of the j-th passive broadband oscillation suppression strategy, is the input matrix of the j-th passive broadband oscillation suppression strategy, is the input variable of the j-th passive broadband oscillation suppression strategy;

[0013] Step S3: Based on the state space model established in step S2, a state space model of a wind power flexible low-frequency grid-connected system is established with different broadband oscillation suppression strategies set at different locations of the wind turbine converter, collector line, and AC converter;

[0014] Step S4: according to the state space model of the wind power flexible low-frequency grid-connected system established in step S3, obtaining the optimal installation position under the wide-band oscillation suppression strategy under the non-target frequency band damping constraint;

[0015] Step S4.1: Analyze the changes in broadband damping before and after different broadband oscillation suppression strategies are set at different positions;

[0016] Step S4.2: Based on the analysis results of step S4.1, obtain the broadband damping transfer law when different broadband oscillation suppression strategies are set at different positions;

[0017] Step S4.3: Select the optimal installation location of different broadband oscillation suppression strategies under the non-target band damping constraint according to the broadband damping transfer law;

[0018] Step S5: selecting the type of the multi-strategy coordinated wideband oscillation uniform suppression strategy based on the optimal installation position obtained in step S4;

[0019] Step S5.1: Obtain uniform damping of the wind power flexible low-frequency grid-connected system ;

[0020] Step S5.2: Add the broadband oscillation suppression strategy under the optimal installation position to the broadband damping of the system. By comparison, the types of active / passive broadband oscillation suppression strategies are obtained and used in the wind power flexible low-frequency grid-connected system to achieve broadband oscillation suppression.

[0021] The multi-strategy coordinated broadband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to the present invention is also characterized in that the state variable of the wind power flexible low-frequency grid-connected system in step S1 is

[0022] , where ws is the speed of the wind turbine, ids and iqs are the d-axis and q-axis currents of the wind turbine stator in the synchronous coordinate system, udc is the DC capacitor voltage of the wind turbine, idg and iqg are the d-axis and q-axis currents of the wind turbine grid-side converter outlet, udg and uqg are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet, id and iq are the d-axis and q-axis currents of the collector line, xa and xb are the two state variables of the wind turbine phase-locked loop, xlow1 and xlow2 are the two state variables of the flexible low-frequency system phase-locked loop, idlow and iqlow are the d-axis and q-axis currents of the flexible low-frequency system, udlow and uqlow are the d-axis and q-axis voltages of the flexible low-frequency system;

[0023] Input variables of wind power flexible low-frequency grid-connected system , where idsref is the d-axis reference value of the wind turbine stator, wsref is the speed reference value of the wind turbine, udcref is the DC capacitor voltage reference value of the wind turbine, iqref is the q-axis current reference value of the output side of the wind turbine grid-side converter, udlowref and uqlowref are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system, respectively.

[0024] Furthermore, in step S2:

[0025] , where ws_i is the wind turbine speed under the i-th active broadband oscillation suppression strategy, ids_i and iqs_i are the d-axis and q-axis currents of the wind turbine stator under the i-th active broadband oscillation suppression strategy, udc_i is the DC capacitor voltage of the wind turbine under the i-th active broadband oscillation suppression strategy, idg_i and iqg_i are the d-axis and q-axis currents of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, udg_i and uqg_i are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, id_i and iq_i are the are the d-axis and q-axis currents of the collector line under the i-th active wide-band oscillation suppression strategy, xa_i and xb_i are the two state variables of the wind turbine phase-locked loop under the i-th active wide-band oscillation suppression strategy, xlow1_i and xlow2_i are the two state variables of the flexible low-frequency system phase-locked loop under the i-th active wide-band oscillation suppression strategy, idlow_i and iqlow_i are the d-axis and q-axis currents under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy, udlow_i and uqlow_i are the d-axis and q-axis voltages under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy;

[0026] , where idsref_i is the d-axis reference value of the wind turbine stator under the i-th active broadband oscillation suppression strategy, wsref_i is the wind turbine speed reference value under the i-th active broadband oscillation suppression strategy, udcref_i is the wind turbine DC capacitor voltage reference value under the i-th active broadband oscillation suppression strategy, iqref_i is the reference value of the q-axis current on the grid-side converter outlet side of the wind turbine under the i-th active broadband oscillation suppression strategy, udlowref_i and uqlowref_i are the reference values ​​of the d-axis and q-axis voltages of the flexible low-frequency system under the i-th active broadband oscillation suppression strategy, respectively;

[0027] , where ws_j is the wind turbine speed under the j-th passive broadband oscillation suppression strategy, ids_j and iqs_j are the d-axis and q-axis currents of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the j-th passive broadband oscillation suppression strategy, idg_j and iqg_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udg_j and uqg_j are the d-axis and q-axis voltages of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, id_j and iq_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, are the d-axis and q-axis currents of the collector line under the j-th passive broadband oscillation suppression strategy, xa_j and xb_j are the two state variables of the wind turbine phase-locked loop under the j-th passive broadband oscillation suppression strategy, xlow1_j and xlow2_j are the two state variables of the flexible low-frequency system phase-locked loop under the j-th passive broadband oscillation suppression strategy, idlow_j and iqlow_j are the d-axis and q-axis currents of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, udlow_j and uqlow_j are the d-axis and q-axis voltages of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy;

[0028] , where idsref_j is the d-axis reference value of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, wsref_j is the wind turbine speed reference value under the j-th passive broadband oscillation suppression strategy, udcref_j is the DC capacitor voltage reference value of the wind turbine under the j-th passive broadband oscillation suppression strategy, iqref_j is the export side q-axis current reference value of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udlowref_j and uqlowref_j are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, respectively.

[0029] Furthermore, step S3 includes:

[0030] Step S3.1: Use equations (4) to (6) to establish the interface relationship between the wind power flexible low-frequency grid-connected system when the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy are respectively set in the wind turbine converter, collector line, and AC converter:

[0031] (4)

[0032] (5)

[0033] (6)

[0034] In formulas (4) to (6), the variable subscript -w indicates that the broadband oscillation suppression strategy is installed on the wind turbine converter, -c indicates that the broadband oscillation suppression strategy is installed on the collector line, and -v indicates that the broadband oscillation suppression strategy is installed on the AC converter.

[0035] In formula (4), is the voltage variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the voltage variable of the wind power flexible low-frequency grid-connected system, represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system and the wind power converter when the i-th active wide-band oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the current variable of the wind power flexible low-frequency grid-connected system, The variable representing the current interface between the wind power flexible low-frequency grid-connected system and the i-th active wide-band oscillation suppression strategy when it is installed in the wind turbine converter, collector line, and AC converter respectively;

[0036] In formula (5), is the voltage variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively;

[0037] In formula (6), represents the coordinate system of the i-th active broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, is the coordinate system of the wind power flexible low-frequency grid-connected system, The variable representing the interface between the coordinate system of the i-th active wide-band oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system, represents the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, The variable representing the interface between the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system;

[0038] Step S3.2: Using equations (7) and (8), obtain the state space model of the wind power flexible low-frequency grid-connected system set at different locations under different broadband oscillation suppression strategies;

[0039] (7)

[0040] (8)

[0041] In formula (7), is the state variable of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line, and AC converter when the i-th active wide-band oscillation suppression strategy is applied respectively;

[0042] In formula (8), The state variables of the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line, and AC converter when the j-th passive wide-band oscillation suppression strategy is used.

[0043] Furthermore, the step S4.1 includes:

[0044] Step S4.1.1: Use Equation (9) to establish a linearized state space model of the wind power flexible low-frequency grid-connected system:

[0045] (9)

[0046] In formula (9), express the increment;

[0047] Step S4.1.2: Use equations (10) and (11) to establish the linearized state space model of the wind power flexible low-frequency grid-connected system under different installation locations and different active / passive broadband oscillation suppression strategies:

[0048] (10)

[0049] (11)

[0050] In formula (10) and formula (11), express the increment; express the increment;

[0051] Step S4.1.3: Solve the state matrix in equation (9) separately Damping ratio of low-frequency band eigenvalue, mid-frequency band eigenvalue, and high-frequency band eigenvalue 、 、 ;

[0052] Solve the state matrix in equation (10) separately Damping ratio of low-frequency band eigenvalue, mid-frequency band eigenvalue, and high-frequency band eigenvalue 、 、 ;

[0053] Solve the state matrix in equation (11) separately Damping ratio in low frequency band, mid frequency band and high frequency band 、 、 ;

[0054] When the i-th active broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively, the damping variation of the wind power flexible low-frequency grid-connected system in the low frequency band, medium frequency band and high frequency band is calculated as follows: 、 、 ;

[0055] When the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively, the damping variation of the wind power flexible low-frequency grid-connected system in the low frequency band, medium frequency band and high frequency band is calculated as follows: 、 、 .

[0056] Furthermore, the step S4.2 includes:

[0057] After adding the i-th active broadband oscillation suppression strategy, the damping changes in different frequency bands are 、 、 The positive and negative signs of , after the i-th active wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change;

[0058] After adding the jth passive broadband oscillation suppression strategy, the damping changes in different frequency bands 、 、 The positive and negative signs of , after the j-th passive wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change.

[0059] Furthermore, the step S4.3 includes:

[0060] Step S4.3.1: Set the non-target frequency band damping of the i-th active wideband oscillation suppression strategy to be no less than , then after the i-th active broadband oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 When it is negative, the corresponding frequency band is the non-target frequency band of the i-th active wide-band oscillation suppression strategy;

[0061] Step S4.3.2 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active wide-band oscillation suppression strategy when it is set in the wind turbine converter. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind1 ;

[0062] Step S4.3.3 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active broadband oscillation suppression strategy when it is set on the collector line. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L line1 ;

[0063] Step S4.3.4 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active wide-band oscillation suppression strategy when the AC converter is set. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L conveter1 ;

[0064] Step S4.3.5 Compare the selected addition position L wind1 , L line1 and L conveter1 The damping of the corresponding non-target frequency band is selected, and the maximum damping of the non-target frequency band is selected as the optimal installation position L of the active wide-band oscillation suppression strategy under the non-target frequency band damping constraint. actbest ;

[0065] Step S4.3.6 sets the non-target frequency band damping of the jth passive broadband oscillation suppression strategy to be no less than ; After the j-th source wide-band oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 The corresponding frequency band when is negative is the non-target frequency band of the j-th passive wide-band oscillation suppression strategy;

[0066] Step S4.3.6 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when different passive broadband oscillation suppression strategies are set in the wind turbine converter. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind2 ;

[0067] Step S4.3.7 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the collector line is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L line2 ;

[0068] Step S4.3.8 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the AC converter is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L conveter2 ;

[0069] Step S4.3.9 Compare the selected addition position L wind2 , L line2 and L conveter2 The corresponding non-target frequency band damping is selected, and the maximum non-target frequency band damping is selected as the optimal installation position L of the passive broadband oscillation suppression strategy under the non-target frequency band damping constraint. pasbest .

[0070] Furthermore, the step S5.1 includes:

[0071] Step S5.1.1: Use Equation (12) to obtain the total damping of the wind power flexible low-frequency grid-connected system :

[0072] (12)

[0073] Step S5.1.2: Use Equation (13) to obtain the uniform damping of the wind power flexible low-frequency grid-connected system :

[0074] (13)

[0075] Furthermore, the step S5.2 includes:

[0076] Step S5.2.1: Use formula (14) to obtain the optimal installation position L actbest After the i-th active broadband oscillation suppression strategy is added, the difference between broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system is , thus obtaining the addition position L actbest After each active broadband oscillation suppression strategy is added, the difference between the broadband damping and the uniform damping of the wind power flexible low-frequency grid-connected system is calculated, and the active broadband oscillation suppression strategy corresponding to the minimum value is selected as the type of active broadband oscillation suppression strategy;

[0077] (14)

[0078] Step S5.2.2: Use formula (15) to obtain the optimal installation position L pasbest After the jth passive broadband oscillation suppression strategy is added, the difference between broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system is , thus obtaining the optimal installation position L pasbestAfter each passive broadband oscillation suppression strategy is added, the difference between the broadband damping and the uniform damping of the wind power flexible low-frequency grid-connected system is calculated, and the passive broadband oscillation suppression strategy corresponding to the minimum value is selected as the type of the selected passive broadband oscillation suppression strategy;

[0079] (15).

[0080] The electronic device of the present invention includes a memory and a processor, and is characterized in that the memory is used to store a program that supports the processor to execute the multi-strategy coordinated wide-band oscillation uniform suppression method, and the processor is configured to execute the program stored in the memory.

[0081] The present invention provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium. The characteristic is that the computer program executes the steps of the multi-strategy coordinated wideband oscillation uniform suppression method when the computer program is run by a processor.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] 1. This paper analyzes the broadband damping transmission patterns of different broadband oscillation suppression strategies at different installation locations (wind turbine converters, collector lines, and AC converters), considers the constraints of non-target frequency band damping, and proposes a method for selecting installation locations for different broadband oscillation suppression strategies under non-target frequency band damping constraints. This method avoids the situation where non-target frequency band damping deteriorates into negative damping after the installation of a single oscillation suppression strategy, leading to system instability.

[0084] 2. The present invention adopts a multi-strategy collaborative approach and selects the types of multi-strategy collaborative wide-band oscillation suppression strategies according to the principle of uniform suppression of wide-band oscillations, and proposes a method for selecting the types of multi-strategy collaborative wide-band oscillation uniform suppression strategies, which can enable the wind power flexible low-frequency grid-connected system to have a large approximate positive damping in the low-frequency band, medium-frequency band, and high-frequency band, thereby ensuring that the wind power flexible low-frequency grid-connected system has a large stability margin in the wide band. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a structural diagram of the wind power flexible low-frequency grid-connected system of the present invention;

[0086] Figure 2 Flowchart of the present invention. DETAILED DESCRIPTION

[0087] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0088] In this embodiment, Figure 1As shown in the figure, the wind power flexible low-frequency grid-connected system mainly includes: wind turbines, collection lines, flexible low-frequency (flexible direct current transmission is referred to as flexible low-frequency) system;

[0089] like Figure 2 As shown, a multi-strategy coordinated broadband oscillation uniform suppression strategy for a wind power flexible low-frequency grid-connected system is implemented in the following steps:

[0090] Step S1: Establishing a state space model of a wind power flexible low-frequency grid-connected system under different broadband oscillation suppression strategies at different installation locations;

[0091] Step S1.1: Establish a state space model for the wind power flexible low-frequency grid-connected system:

[0092] Step S1.1.1: Use equation (1) to establish the state space model of the wind power flexible low-frequency grid-connected system:

[0093] (1)

[0094] In formula (1), represents the differential, x wv is the state variable of the wind power flexible low-frequency grid-connected system, t is time, A wv is the state matrix of the wind power flexible low-frequency grid-connected system, B wv is the input matrix of the wind power flexible low-frequency grid-connected system, u wv are the input variables of the wind power flexible low-frequency grid-connected system. And:

[0095] , where ws is the speed of the wind turbine, ids and iqs are the d-axis and q-axis currents of the wind turbine stator in the synchronous coordinate system, udc is the DC capacitor voltage of the wind turbine, idg and iqg are the d-axis and q-axis currents of the wind turbine grid-side converter outlet, udg and uqg are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet, id and iq are the d-axis and q-axis currents of the collector line, xa and xb are the two state variables of the wind turbine phase-locked loop, xlow1 and xlow2 are the two state variables of the flexible low-frequency system phase-locked loop, idlow and iqlow are the d-axis and q-axis currents of the flexible low-frequency system, udlow and uqlow are the d-axis and q-axis voltages of the flexible low-frequency system;

[0096] , where idsref is the d-axis reference value of the wind turbine stator, wsref is the speed reference value of the wind turbine, udcref is the DC capacitor voltage reference value of the wind turbine, iqref is the q-axis current reference value of the output side of the wind turbine grid-side converter, udlowref and uqlowref are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system respectively;

[0097] Step S1.2: Establish a state-space model for a single broadband oscillation suppression strategy:

[0098] Step S1.2.1: Use equations (2) and (3) to establish the state space models of the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy respectively:

[0099] (2)

[0100] (3)

[0101] In formula (2) and formula (3), is the state variable of the i-th active broadband oscillation suppression strategy, is the state matrix of the i-th active broadband oscillation suppression strategy, is the input matrix of the i-th active broadband oscillation suppression strategy, is the input variable of the i-th active broadband oscillation suppression strategy; is the state variable of the j-th passive broadband oscillation suppression strategy, is the state matrix of the j-th passive broadband oscillation suppression strategy, is the input matrix of the j-th passive broadband oscillation suppression strategy, is the input variable of the j-th passive broadband oscillation suppression strategy. And:

[0102] , where ws_i is the wind turbine speed under the i-th active broadband oscillation suppression strategy, ids_i and iqs_i are the d-axis and q-axis currents of the wind turbine stator under the i-th active broadband oscillation suppression strategy, udc_i is the DC capacitor voltage of the wind turbine under the i-th active broadband oscillation suppression strategy, idg_i and iqg_i are the d-axis and q-axis currents of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, udg_i and uqg_i are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, id_i and iq_i are the are the d-axis and q-axis currents of the collector line under the i-th active wide-band oscillation suppression strategy, xa_i and xb_i are the two state variables of the wind turbine phase-locked loop under the i-th active wide-band oscillation suppression strategy, xlow1_i and xlow2_i are the two state variables of the flexible low-frequency system phase-locked loop under the i-th active wide-band oscillation suppression strategy, idlow_i and iqlow_i are the d-axis and q-axis currents under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy, udlow_i and uqlow_i are the d-axis and q-axis voltages under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy;

[0103] , where idsref_i is the d-axis reference value of the wind turbine stator under the i-th active broadband oscillation suppression strategy, wsref_i is the wind turbine speed reference value under the i-th active broadband oscillation suppression strategy, udcref_i is the wind turbine DC capacitor voltage reference value under the i-th active broadband oscillation suppression strategy, iqref_i is the reference value of the q-axis current on the grid-side converter outlet side of the wind turbine under the i-th active broadband oscillation suppression strategy, udlowref_i and uqlowref_i are the reference values ​​of the d-axis and q-axis voltages of the flexible low-frequency system under the i-th active broadband oscillation suppression strategy, respectively;

[0104] , where ws_j is the wind turbine speed under the j-th passive broadband oscillation suppression strategy, ids_j and iqs_j are the d-axis and q-axis currents of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the j-th passive broadband oscillation suppression strategy, idg_j and iqg_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udg_j and uqg_j are the d-axis and q-axis voltages of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, id_j and iq_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, are the d-axis and q-axis currents of the collector line under the j-th passive broadband oscillation suppression strategy, xa_j and xb_j are the two state variables of the wind turbine phase-locked loop under the j-th passive broadband oscillation suppression strategy, xlow1_j and xlow2_j are the two state variables of the flexible low-frequency system phase-locked loop under the j-th passive broadband oscillation suppression strategy, idlow_j and iqlow_j are the d-axis and q-axis currents of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, udlow_j and uqlow_j are the d-axis and q-axis voltages of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy;

[0105] , where idsref_j is the d-axis reference value of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, wsref_j is the wind turbine speed reference value under the j-th passive broadband oscillation suppression strategy, udcref_j is the DC capacitor voltage reference value of the wind turbine under the j-th passive broadband oscillation suppression strategy, iqref_j is the export side q-axis current reference value of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udlowref_j and uqlowref_j are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, respectively;

[0106] Step S1.3: Establish the state space model of the wind power flexible low-frequency grid-connected system under different broadband oscillation suppression strategies and different installation locations:

[0107] Step S1.3.1: Use equations (4) to (6) to establish the interface relationship between the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy when they are installed on the wind turbine converter, collector line, and AC converter respectively, and the wind power flexible low-frequency grid-connected system:

[0108] (4)

[0109] (5)

[0110] (6)

[0111] In formulas (4) to (6), the variable subscript -w indicates that the broadband oscillation suppression strategy is installed on the wind turbine converter, -c indicates that the broadband oscillation suppression strategy is installed on the collector line, and -v indicates that the broadband oscillation suppression strategy is installed on the AC converter.

[0112] In formula (4), is the voltage variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the voltage variable of the wind power flexible low-frequency grid-connected system, represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system and the wind power converter when the i-th active wide-band oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the current variable of the wind power flexible low-frequency grid-connected system, The variable representing the current interface between the wind power flexible low-frequency grid-connected system and the i-th active wide-band oscillation suppression strategy when it is installed in the wind turbine converter, collector line, and AC converter respectively;

[0113] In formula (5), is the voltage variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively;

[0114] In formula (6), represents the coordinate system of the i-th active broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, is the coordinate system of the wind power flexible low-frequency grid-connected system, The variable representing the interface between the coordinate system of the i-th active wide-band oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system, represents the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, The variable representing the interface between the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system;

[0115] Step S1.3.2: Combining the state space model of the wind power flexible low-frequency grid-connected system in equation (1), the state space models of different broadband oscillation suppression strategies in equations (2)-(3), and the interface relationships between broadband oscillation suppression strategies set at different locations and the wind power flexible low-frequency grid-connected system in equations (4)-(6), the state space models of the wind power flexible low-frequency grid-connected system with broadband oscillation suppression strategies set at different locations can be obtained, as shown in equations (7) and (8);

[0116] (7)

[0117] (8)

[0118] In formula (7), is the state variable of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line, and AC converter when the i-th active wide-band oscillation suppression strategy is applied respectively;

[0119] In formula (8), The state variables of the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line and AC converter respectively when the j-th passive broadband oscillation suppression strategy is applied;

[0120] Step S2: Obtaining the installation position of the wide-band oscillation suppression strategy under the non-target frequency band damping constraint;

[0121] Step S2.1: Analyze the changes in broadband damping before and after different broadband oscillation suppression strategies are set at different positions:

[0122] Step S2.1.1: Linearize equation (1) and use equation (9) to establish the linearized state space model of the wind power flexible low-frequency grid-connected system:

[0123] (9)

[0124] In formula (9), express increment.

[0125] Step S2.1.2: Linearize Equations (7) and (8), and use Equations (10) and (11) to establish the linearized state space model of the wind power flexible low-frequency grid-connected system under different installation locations and different active / passive broadband oscillation suppression strategies:

[0126] (10)

[0127] (11)

[0128] In formula (10) and formula (11), express the increment; express the increment;

[0129] Step S2.1.3: Solve the state matrix in equation (9) separately Damping ratio of eigenvalues ​​in low frequency band, mid frequency band and high frequency band 、 、 ;

[0130] Solve the state matrix in equation (10) separately Damping ratio of eigenvalues ​​in low frequency band, mid frequency band and high frequency band 、 、 ;

[0131] Solve the state matrix in equation (11) separately Damping ratio of eigenvalues ​​in low frequency band, mid frequency band and high frequency band 、 、 ;

[0132] Calculate the damping variation of the wind power flexible low-frequency grid-connected system in the low-frequency band, medium-frequency band and high-frequency band when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively: 、 、 ;

[0133] Calculate the damping variation of the wind power flexible low-frequency grid-connected system in the low-frequency band, medium-frequency band and high-frequency band when the j-th passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively: 、 、 .

[0134] Step S2.2: Obtain the broadband damping transfer laws of different broadband oscillation suppression strategies at different installation positions:

[0135] After adding the i-th active broadband oscillation suppression strategy, the damping changes in different frequency bands are 、 、 The positive and negative signs of , after the i-th active wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change;

[0136] After adding the jth passive broadband oscillation suppression strategy, the damping changes in different frequency bands 、 、 The positive and negative signs of , after the j-th passive wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change;.

[0137] Step S2.3: Select the installation locations of different broadband oscillation suppression strategies under non-target frequency band damping constraints:

[0138] Step S2.3.1: Set the non-target frequency band damping of the i-th active wideband oscillation suppression strategy to be no less than , then after the i-th active broadband oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 When it is negative, the corresponding frequency band is the non-target frequency band of the i-th active wide-band oscillation suppression strategy;

[0139] Step S2.3.2 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active wide-band oscillation suppression strategy when it is set in the wind turbine converter. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind1 ;

[0140] Step S2.3.3 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active broadband oscillation suppression strategy when it is set on the collector line. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L line1 ;

[0141] Step S2.3.4 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active broadband oscillation suppression strategy when the AC converter is set. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L conveter1 ;

[0142] Step S2.3.5 Compare the selected addition position L wind1 , L line1 and L conveter1 The damping of the corresponding non-target frequency band is selected, and the maximum damping of the non-target frequency band is selected as the optimal installation position L of the active wide-band oscillation suppression strategy under the non-target frequency band damping constraint. actbest ;

[0143] Step S2.3.6 sets the non-target frequency band damping of the jth passive broadband oscillation suppression strategy to be no less than ; After the j-th source wide-band oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 The corresponding frequency band when is negative is the non-target frequency band of the j-th passive wide-band oscillation suppression strategy;

[0144] Step S2.3.6 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when different passive broadband oscillation suppression strategies are set in the wind turbine converter. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind2 ;

[0145] Step S2.3.7 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the collector line is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L line2 ;

[0146] Step S2.3.8 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the AC converter is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L conveter2 ;

[0147] Step S2.3.9 Compare the selected addition position L wind2 , L line2 and L conveter2 The corresponding non-target frequency band damping is selected, and the maximum non-target frequency band damping is selected as the optimal installation position L of the passive broadband oscillation suppression strategy under the non-target frequency band damping constraint. pasbest ;

[0148] Step S3: Select the type of multi-strategy coordinated broadband oscillation uniform suppression strategy;

[0149] Step S3.1: Obtain uniform damping of the wind power flexible low-frequency grid-connected system:

[0150] Step S3.1.1: Use Equation (12) to obtain the total damping of the wind power flexible low-frequency grid-connected system :

[0151] (12)

[0152] Step S3.1.2: Due to the total damping is the sum of the damping of the low-frequency band, the medium-frequency band, and the high-frequency band. Therefore, the uniform damping of the wind power flexible low-frequency grid-connected system can be obtained using formula (13): :

[0153] (13)

[0154] Step S3.2: Obtain the type of active / passive broadband oscillation suppression strategy.

[0155] Step S3.2.1: Use formula (14) to obtain the difference between the broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system after adding different active broadband oscillation suppression strategies. :

[0156] (14)

[0157] In formula (14) The optimal installation position L corresponding to the minimum value actbest The i-th active broadband oscillation suppression strategy is the type of active broadband oscillation suppression strategy selected;

[0158] Step S3.2.2: Use formula (15) to obtain the difference between the broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system after adding different passive broadband oscillation suppression strategies. :

[0159] (15)

[0160] In formula (15) The optimal installation position L corresponding to the minimum value pasbest The j-th passive broadband oscillation suppression strategy is the type of the selected passive broadband oscillation suppression strategy.

[0161] Based on the principle of non-target damping constraint, combined with the installation location of the multi-strategy coordinated wide-band oscillation suppression strategy in step 2 and the selection of the type of the multi-strategy coordinated wide-band oscillation suppression strategy in step 3, a multi-strategy coordinated wide-band oscillation uniform suppression strategy for the wind power flexible low-frequency grid-connected system is obtained, which realizes that the wind power flexible low-frequency grid-connected system has large approximate positive damping in the low-frequency band, medium-frequency band and high-frequency band, ensures that the wind power flexible low-frequency grid-connected system has a large stability margin in the wide band, and reduces the risk of wide-band oscillation.

[0162] In this embodiment, an electronic device includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the above method, and the processor is configured to execute the program stored in the memory.

[0163] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are executed.

Claims

1. A multi-strategy coordinated broadband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system, the wind power flexible low-frequency grid-connected system mainly comprising: Wind turbine, collector line, flexible low-frequency system; characterized in that the multi-strategy coordinated broadband oscillation uniform suppression method is carried out in the following steps: Step S1: Use equation (1) to establish the state space model of the wind power flexible low-frequency grid-connected system: (1) In formula (1), represents the differential, x wv is the state variable of the wind power flexible low-frequency grid-connected system, t is time, u wv is the input variable of the wind power flexible low-frequency grid-connected system, A wv is the state matrix of the wind power flexible low-frequency grid-connected system, B wv It is the input matrix of the wind power flexible low-frequency grid-connected system; Step S2: Using equations (2) and (3), establish the state space model of the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy respectively: (2) (3) In formula (2), is the state variable of the i-th active broadband oscillation suppression strategy, is the state matrix of the i-th active broadband oscillation suppression strategy, is the input matrix of the i-th active broadband oscillation suppression strategy, is the input variable of the i-th active broadband oscillation suppression strategy; is the state variable of the j-th passive broadband oscillation suppression strategy, is the state matrix of the j-th passive broadband oscillation suppression strategy, is the input matrix of the j-th passive broadband oscillation suppression strategy, is the input variable of the j-th passive broadband oscillation suppression strategy; Step S3: Based on the state space model established in step S2, a state space model of a wind power flexible low-frequency grid-connected system is established with different broadband oscillation suppression strategies set at different locations of the wind turbine converter, collector line, and AC converter; Step S4: according to the state space model of the wind power flexible low-frequency grid-connected system established in step S3, obtaining the optimal installation position under the wide-band oscillation suppression strategy under the non-target frequency band damping constraint; Step S4.1: Analyze the changes in broadband damping before and after different broadband oscillation suppression strategies are set at different positions; Step S4.2: Based on the analysis results of step S4.1, obtain the broadband damping transfer law when different broadband oscillation suppression strategies are set at different positions; Step S4.3: Select the optimal installation location of different broadband oscillation suppression strategies under the non-target band damping constraint according to the broadband damping transfer law; Step S5: selecting the type of the multi-strategy coordinated wideband oscillation uniform suppression strategy based on the optimal installation position obtained in step S4; Step S5.1: Obtain uniform damping of the wind power flexible low-frequency grid-connected system ; Step S5.2: Add the broadband oscillation suppression strategy under the optimal installation position to the broadband damping of the system. By comparison, the types of active / passive broadband oscillation suppression strategies are obtained and used in the wind power flexible low-frequency grid-connected system to achieve broadband oscillation suppression.

2. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 1, characterized in that: State variables of the wind power flexible low-frequency grid-connected system in step S1 , where ws is the speed of the wind turbine, ids and iqs are the d-axis and q-axis currents of the wind turbine stator in the synchronous coordinate system, udc is the DC capacitor voltage of the wind turbine, idg and iqg are the d-axis and q-axis currents of the wind turbine grid-side converter outlet, udg and uqg are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet, id and iq are the d-axis and q-axis currents of the collector line, xa and xb are the two state variables of the wind turbine phase-locked loop, xlow1 and xlow2 are the two state variables of the flexible low-frequency system phase-locked loop, idlow and iqlow are the d-axis and q-axis currents of the flexible low-frequency system, udlow and uqlow are the d-axis and q-axis voltages of the flexible low-frequency system; Input variables of wind power flexible low-frequency grid-connected system , where idsref is the d-axis reference value of the wind turbine stator, wsref is the speed reference value of the wind turbine, udcref is the DC capacitor voltage reference value of the wind turbine, iqref is the q-axis current reference value of the output side of the wind turbine grid-side converter, udlowref and uqlowref are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system, respectively.

3. The multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 2 is characterized in that: In step S2: ， Among them, ws_i is the speed of the wind turbine under the i-th active broadband oscillation suppression strategy, ids_i and iqs_i are the d-axis and q-axis currents of the wind turbine stator under the i-th active broadband oscillation suppression strategy, udc_i is the DC capacitor voltage of the wind turbine under the i-th active broadband oscillation suppression strategy, idg_i and iqg_i are the d-axis and q-axis currents of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, udg_i and uqg_i are the d-axis and q-axis voltages of the wind turbine grid-side converter outlet under the i-th active broadband oscillation suppression strategy, id_i and iq_i are respectively are the d-axis and q-axis currents of the collector line under the i-th active wide-band oscillation suppression strategy, xa_i and xb_i are the two state variables of the wind turbine phase-locked loop under the i-th active wide-band oscillation suppression strategy, xlow1_i and xlow2_i are the two state variables of the flexible low-frequency system phase-locked loop under the i-th active wide-band oscillation suppression strategy, idlow_i and iqlow_i are the d-axis and q-axis currents under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy, udlow_i and uqlow_i are the d-axis and q-axis voltages under the flexible low-frequency system under the i-th active wide-band oscillation suppression strategy; , where idsref_i is the d-axis reference value of the wind turbine stator under the i-th active broadband oscillation suppression strategy, wsref_i is the wind turbine speed reference value under the i-th active broadband oscillation suppression strategy, udcref_i is the wind turbine DC capacitor voltage reference value under the i-th active broadband oscillation suppression strategy, iqref_i is the reference value of the q-axis current on the grid-side converter outlet side of the wind turbine under the i-th active broadband oscillation suppression strategy, udlowref_i and uqlowref_i are the reference values ​​of the d-axis and q-axis voltages of the flexible low-frequency system under the i-th active broadband oscillation suppression strategy, respectively; ， Among them, ws_j is the wind turbine speed under the j-th passive broadband oscillation suppression strategy, ids_j and iqs_j are the d-axis and q-axis currents of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the j-th passive broadband oscillation suppression strategy, idg_j and iqg_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udg_j and uqg_j are the d-axis and q-axis voltages of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, id_j and iq_j are the d-axis and q-axis currents of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, respectively. are the d-axis and q-axis currents of the collector line under the j-th passive broadband oscillation suppression strategy, xa_j and xb_j are the two state variables of the wind turbine phase-locked loop under the j-th passive broadband oscillation suppression strategy, xlow1_j and xlow2_j are the two state variables of the flexible low-frequency system phase-locked loop under the j-th passive broadband oscillation suppression strategy, idlow_j and iqlow_j are the d-axis and q-axis currents of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, udlow_j and uqlow_j are the d-axis and q-axis voltages of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy; , where idsref_j is the d-axis reference value of the wind turbine stator under the j-th passive broadband oscillation suppression strategy, wsref_j is the wind turbine speed reference value under the j-th passive broadband oscillation suppression strategy, udcref_j is the DC capacitor voltage reference value of the wind turbine under the j-th passive broadband oscillation suppression strategy, iqref_j is the export side q-axis current reference value of the wind turbine grid-side converter under the j-th passive broadband oscillation suppression strategy, udlowref_j and uqlowref_j are the d-axis and q-axis voltage reference values ​​of the flexible low-frequency system under the j-th passive broadband oscillation suppression strategy, respectively.

4. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 3, characterized in that: Step S3 includes: Step S3.1: Use equations (4) to (6) to establish the interface relationship between the wind power flexible low-frequency grid-connected system when the i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy are respectively set in the wind turbine converter, collector line, and AC converter: (4) (5) (6) In formulas (4) to (6), the variable subscript -w indicates that the broadband oscillation suppression strategy is installed on the wind turbine converter, -c indicates that the broadband oscillation suppression strategy is installed on the collector line, and -v indicates that the broadband oscillation suppression strategy is installed on the AC converter. In formula (4), is the voltage variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the voltage variable of the wind power flexible low-frequency grid-connected system, represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system and the wind power converter when the i-th active wide-band oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the i-th active broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively, is the current variable of the wind power flexible low-frequency grid-connected system, The variable representing the current interface between the wind power flexible low-frequency grid-connected system and the i-th active wide-band oscillation suppression strategy when it is installed in the wind turbine converter, collector line, and AC converter respectively; In formula (5), is the voltage variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. is the current variable when the jth passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively. represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is installed in the wind turbine converter, collector line, and AC converter respectively; In formula (6), represents the coordinate system of the i-th active broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, is the coordinate system of the wind power flexible low-frequency grid-connected system, The variable representing the interface between the coordinate system of the i-th active wide-band oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system, represents the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter, The variable representing the interface between the coordinate system of the jth passive broadband oscillation suppression strategy installed in the wind turbine converter, collector line, and AC converter and the coordinate system of the wind power flexible low-frequency grid-connected system; Step S3.2: Using equations (7) and (8), obtain the state space model of the wind power flexible low-frequency grid-connected system set at different locations under different broadband oscillation suppression strategies; (7) (8) In formula (7), is the state variable of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the i-th active wide-band oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line, and AC converter when the i-th active wide-band oscillation suppression strategy is applied respectively; In formula (8), The state variables of the wind power flexible low-frequency grid-connected system when the j-th passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the state matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. is the input matrix of the wind power flexible low-frequency grid-connected system when the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line, and AC converter respectively. The input variables of the wind power flexible low-frequency grid-connected system are set at the wind turbine converter, collector line, and AC converter when the j-th passive wide-band oscillation suppression strategy is used.

5. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 4, characterized in that: The step S4.1 includes: Step S4.1.1: Use Equation (9) to establish a linearized state space model of the wind power flexible low-frequency grid-connected system: (9) In formula (9), express the increment; Step S4.1.2: Use equations (10) and (11) to establish the linearized state space model of the wind power flexible low-frequency grid-connected system under different installation locations and different active / passive broadband oscillation suppression strategies: (10) (11) In formula (10) and formula (11), express the increment; express the increment; Step S4.1.3: Solve the state matrix in equation (9) separately Damping ratio of low-frequency band eigenvalue, mid-frequency band eigenvalue, and high-frequency band eigenvalue 、 、 ; Solve the state matrix in equation (10) separately Damping ratio of low-frequency band eigenvalue, mid-frequency band eigenvalue, and high-frequency band eigenvalue 、 、 ; Solve the state matrix in equation (11) separately Damping ratio in low frequency band, mid frequency band and high frequency band 、 、 ; When the i-th active broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively, the damping variation of the wind power flexible low-frequency grid-connected system in the low frequency band, medium frequency band and high frequency band is calculated as follows: 、 、 ; When the jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively, the damping variation of the wind power flexible low-frequency grid-connected system in the low frequency band, medium frequency band and high frequency band is calculated as follows: 、 、 .

6. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 5, characterized in that: The step S4.2 includes: After adding the i-th active broadband oscillation suppression strategy, the damping changes in different frequency bands are 、 、 The positive and negative signs of , after the i-th active wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change; After adding the jth passive broadband oscillation suppression strategy, the damping changes in different frequency bands 、 、 The positive and negative signs of , after the j-th passive wide-band oscillation suppression strategy is added, the damping transfer is transferred from the frequency band with negative damping change to the frequency band with positive damping change.

7. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 6, characterized in that: The step S4.3 includes: Step S4.3.1: Set the non-target frequency band damping of the i-th active wideband oscillation suppression strategy to be no less than , then after the i-th active broadband oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 When it is negative, the corresponding frequency band is the non-target frequency band of the i-th active wide-band oscillation suppression strategy; Step S4.3.2 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active wide-band oscillation suppression strategy when it is set in the wind turbine converter. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind1 ; Step S4.3.3 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active broadband oscillation suppression strategy when it is set on the collector line. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L line1 ; Step S4.3.4 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than the value of the active wide-band oscillation suppression strategy when the AC converter is set. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected. Otherwise, the position added under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, and they are respectively recorded as L conveter1 ; Step S4.3.5 Compare the selected addition position L wind1 , L line1 and L conveter1 The damping of the corresponding non-target frequency band is selected, and the maximum damping of the non-target frequency band is selected as the optimal installation position L of the active wide-band oscillation suppression strategy under the non-target frequency band damping constraint. actbest ; Step S4.3.6 sets the non-target frequency band damping of the jth passive broadband oscillation suppression strategy to be no less than ; After the j-th source wide-band oscillation suppression strategy is added, the damping changes in different frequency bands are 、 、 The corresponding frequency band when is negative is the non-target frequency band of the j-th passive wide-band oscillation suppression strategy; Step S4.3.6 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when different passive broadband oscillation suppression strategies are set in the wind turbine converter. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L wind2 ; Step S4.3.7 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the collector line is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L line2 ; Step S4.3.8 Determine whether the damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system is less than when the AC converter is set under different passive broadband oscillation suppression strategies. , if they are all less than, then the position added under each passive broadband oscillation suppression strategy is not selected. Otherwise, the position added under a passive broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, recorded as L conveter2 ; Step S4.3.9 Compare the selected addition position L wind2 , L line2 and L conveter2 The corresponding non-target frequency band damping is selected, and the maximum non-target frequency band damping is selected as the optimal installation position L of the passive broadband oscillation suppression strategy under the non-target frequency band damping constraint. pasbest .

8. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 7, characterized in that: The step S5.1 includes: Step S5.1.1: Use Equation (12) to obtain the total damping of the wind power flexible low-frequency grid-connected system : (12) Step S5.1.2: Use Equation (13) to obtain the uniform damping of the wind power flexible low-frequency grid-connected system : (13)。 9. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 8, characterized in that: The step S5.2 includes: Step S5.2.1: Use formula (14) to obtain the optimal installation position L actbest After the i-th active broadband oscillation suppression strategy is added, the difference between broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system is , thus obtaining the addition position L actbest After each active broadband oscillation suppression strategy is added, the difference between the broadband damping and the uniform damping of the wind power flexible low-frequency grid-connected system is calculated, and the active broadband oscillation suppression strategy corresponding to the minimum value is selected as the type of active broadband oscillation suppression strategy; (14) Step S5.2.2: Use formula (15) to obtain the optimal installation position L pasbest After the jth passive broadband oscillation suppression strategy is added, the difference between broadband damping and uniform damping of the wind power flexible low-frequency grid-connected system is , thus obtaining the optimal installation position L pasbest After each passive broadband oscillation suppression strategy is added, the difference between the broadband damping and the uniform damping of the wind power flexible low-frequency grid-connected system is calculated, and the passive broadband oscillation suppression strategy corresponding to the minimum value is selected as the type of the selected passive broadband oscillation suppression strategy; (15)。 10. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the multi-strategy coordinated wideband oscillation uniform suppression method according to any one of claims 1 to 9, and the processor is configured to execute the program stored in the memory.

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