Multi-strategy collaborative broadband oscillation uniform suppression method of wind power flexible low-frequency grid-connected system

Abstract

The invention discloses a multi-strategy collaborative broadband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system. The method comprises the following steps: 1, establishing a wind power flexible low-frequency grid-connected system state space model under different installation positions and different broadband oscillation suppression strategies; 2, a broadband oscillation suppression strategy installation position under non-target frequency band damping constraint is obtained; and 3, selecting a multi-strategy collaborative broadband oscillation uniform suppression strategy type. The invention provides a multi-strategy collaborative broadband oscillation uniform suppression strategy by considering the problems that non-target frequency band damping is possibly deteriorated and the system is unstable while the target frequency band damping of a wind power flexible low-frequency grid-connected system is improved by the broadband oscillation suppression strategy. After the broadband oscillation suppression strategy is added, any frequency band has uniform positive damping, the stability margin of the wind power flexible low-frequency grid-connected system is improved from the broadband range, and the problem of system instability caused by non-target frequency band damping deterioration is avoided.

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 a wind power flexible low-frequency grid-connected system. Background Art

[0002] Oscillation suppression strategies usually achieve system oscillation suppression by improving the damping of the instability frequency band of the wind power flexible low-frequency grid-connected system. However, there is coupling between the damping of different frequency bands. While improving the damping of the target frequency band, the damping of the non-target frequency band may deteriorate or even become unstable. Therefore, it is difficult to achieve wide-band oscillation suppression with a single suppression strategy. In the Chongqing-Hubei DC back-to-back interconnection project, the 1810Hz high-frequency oscillation on the Hubei side was eliminated after low-pass filtering suppression measures were adopted; however, at this time, a 700Hz medium-frequency oscillation appeared on the Chongqing side. The single oscillation suppression strategy suppressed the specific frequency band while exciting the oscillation of other frequency bands. The document "Analysis of High-Frequency Oscillation Characteristics and Suppression Strategy Research of Flexible DC Transmission System" shows that adding a single damping controller is impossible to improve the stability of the flexible low-frequency system in the full frequency band range. The impedance characteristics of the high-frequency band are more sensitive to the impedance characteristics of the low-frequency band, and the coupling between the high-frequency band damping and the low-frequency band damping is obvious. The document "Impedance Reshaping and Medium- and High-Frequency Oscillation Suppression Method for Flexible DC Transmission" proposes a high-frequency band oscillation suppression method for flexible DC transmission systems based on passive impedance reshapers. While suppressing high-frequency oscillations, medium-frequency oscillations will not be excited. However, the document does not consider the changes in low-frequency band damping during the suppression of medium- and high-frequency oscillations. The low-frequency band damping may become smaller, resulting in system instability. Flexible low-frequency transmission, as a new type of AC transmission technology, is similar to flexible DC transmission systems. It also contains power electronic equipment such as AC converters, which leads to wide-band dynamic coupling in the control link, thus causing wide-band oscillation problems. At the same time, compared with DC transmission systems, flexible low-frequency transmission systems have more heterogeneous frequency interaction characteristics, and their dynamic characteristics are more complex, and the problem of wide-band dynamic interaction is more prominent. The suppression strategies adopted by existing research are difficult to achieve wide-band (including low-frequency band, medium-frequency band and high-frequency band) oscillation suppression in wind power flexible low-frequency grid-connected systems. Summary of the invention

[0003] The present invention aims to solve 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 a wide-band (low-band, medium-band, and 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 a wide-band range.

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

[0005] The present invention discloses a multi-strategy coordinated broadband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system, wherein the wind power flexible low-frequency grid-connected system mainly comprises: a wind turbine set, a collector line, and a flexible low-frequency system; the multi-strategy coordinated broadband oscillation uniform suppression method 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 equation (2) and equation (3), respectively establish the state space model of the i-th active broadband oscillation suppression strategy and the state space model of the j-th passive broadband oscillation suppression strategy:

[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 jth passive broadband oscillation suppression strategy;

[0013] Step S3: According to 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 positions of the wind turbine converter, the collector line, and the 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: analyzing the change of broadband damping before and after different broadband oscillation suppression strategies are set at different positions;

[0016] Step S4.2: according to the analysis result of step S4.1, obtaining the broadband damping transfer law when different broadband oscillation suppression strategies are set at different positions;

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

[0018] Step S5: According to the optimal installation position obtained in step S4, the type of the multi-strategy coordinated wide-band oscillation uniform suppression strategy is selected;

[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 outlet 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 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 at the outlet side of the wind turbine grid-side converter 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 jth 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 jth passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the jth 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 jth 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 jth passive broadband oscillation suppression strategy, id_j and iq_j are the 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] Further, step S3 includes:

[0030] Step S3.1: 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 and the wind power flexible low-frequency grid-connected system when they are respectively set in the wind turbine converter, the collector line, and the AC converter:

[0031] (4)

[0032] (5)

[0033] (6)

[0034] In formula (4) to formula (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 circuit, 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, It represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system 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 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, represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the i-th active broadband oscillation suppression strategy 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 jth 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 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, 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) to obtain the state space model of the wind power flexible low-frequency grid-connected system set at different locations under different wide-band 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 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 i-th active 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 i-th active 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 in the wind turbine converter, collector line and AC converter respectively for the i-th active broadband oscillation suppression strategy;

[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. 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 for the jth passive wide-band oscillation suppression strategy.

[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 of

[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 active / passive broadband oscillation suppression strategies at different installation locations:

[0048] (10)

[0049] (11)

[0050] In formula (10) and formula (11), express The increment of express The increment of

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

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

[0053] Solve the state matrix in equation (11) respectively 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 , , The positive and negative signs of make the damping transfer from the frequency band with negative damping change to the frequency band with positive damping change after the i-th active wide-band oscillation suppression strategy is added;

[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 broadband 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 when the wind turbine converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position 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 when the collector line is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 when the AC converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 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 , , When it is negative, the corresponding frequency band 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 the value set in the wind turbine converter 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 adding position 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 adding position 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 adding position 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, select the maximum non-target frequency band damping 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 selected;

[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] An electronic device of the present invention includes a memory and a processor, wherein 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, and the computer program executes the steps of the multi-strategy coordinated wideband oscillation uniform suppression method when the computer program is executed by a processor.

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

[0083] 1. The present invention analyzes the broadband damping transmission law of different broadband oscillation suppression strategies at different installation locations (wind turbine converter, collector line, AC converter), considers the constraint of non-target frequency band damping, and proposes a method for selecting the installation locations of different broadband oscillation suppression strategies under the constraint of non-target frequency band damping; this method avoids the situation that after the installation of a single oscillation suppression strategy, the non-target frequency band damping may deteriorate into negative damping, resulting in system instability;

[0084] 2. The present invention adopts a multi-strategy coordinated approach and selects the types of multi-strategy coordinated wide-band oscillation suppression strategies according to the principle of wide-band oscillation uniform suppression, and proposes a method for selecting the types of multi-strategy coordinated 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 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0087] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

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

[0089] like Figure 2 As shown, a wind power flexible low-frequency grid-connected system multi-strategy coordinated wide-band oscillation uniform suppression strategy is carried out 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 the state space model of 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 is the input variable 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 outlet 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 the state space model of a single broadband oscillation suppression strategy:

[0098] Step S1.2.1: Use equation (2) and equation (3) to establish the state space model 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 jth 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 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 at the outlet side of the wind turbine grid-side converter 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 jth 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 jth passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the jth 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 jth 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 jth passive broadband oscillation suppression strategy, id_j and iq_j are the 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 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 at 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 in 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 formula (4) to formula (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 circuit, 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, It represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system 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 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, represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the i-th active broadband oscillation suppression strategy 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 jth 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 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, 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 formula (1), the state space models of different wide-band oscillation suppression strategies in formulas (2)-(3), and the interface relationship between the wide-band oscillation suppression strategies set at different positions and the wind power flexible low-frequency grid-connected system in formulas (4)-(6), the state space model of the wind power flexible low-frequency grid-connected system with the wide-band oscillation suppression strategies set at different positions can be obtained, as shown in formulas (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 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 i-th active 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 i-th active 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 in the wind turbine converter, collector line and AC converter respectively for the i-th active broadband oscillation suppression strategy;

[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. 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 in the wind turbine converter, collector line and AC converter respectively for the jth passive broadband oscillation suppression strategy;

[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 a 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 active / passive broadband oscillation suppression strategies at different installation locations:

[0126] (10)

[0127] (11)

[0128] In formula (10) and formula (11), express The increment of express The increment of

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

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

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

[0132] 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 broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively is calculated as follows: , , ;

[0133] 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 jth passive broadband oscillation suppression strategy is set in the wind turbine converter, collector line and AC converter respectively is calculated as follows: , , .

[0134] Step S2.2: Obtain the broadband damping transfer law 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 , , The positive and negative signs of make the damping transfer from the frequency band with negative damping change to the frequency band with positive damping change after the i-th active wide-band oscillation suppression strategy is added;

[0136] After adding the jth passive broadband oscillation suppression strategy, the damping changes in different frequency bands , , The positive and negative signs of the j-th passive wide-band oscillation suppression strategy are added, and 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 broadband 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 when the wind turbine converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position 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 , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 damping of the non-target frequency band of the wind power flexible low-frequency grid-connected system when the AC converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 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 , , When it is negative, the corresponding frequency band 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 the wind turbine 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 adding position 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 adding position 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 adding position 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, select the maximum non-target frequency band damping 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: selecting the type of the multi-strategy coordinated wideband 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 three frequency bands: low frequency band, medium frequency band and 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 wideband oscillation suppression strategy.

[0155] Step S3.2.1: Use equation (14) to obtain the difference between 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 the selected active broadband oscillation suppression strategy;

[0158] Step S3.2.2: Use equation (15) to obtain the difference between 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 jth 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 constraints, combined with the installation position 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 a wind power flexible low-frequency grid-connected system is obtained, which enables the wind power flexible low-frequency grid-connected system to have 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 on the computer-readable storage medium, and the computer program executes the steps of the above method when executed by a processor.

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 equation (2) and equation (3), respectively establish the state space model of the i-th active broadband oscillation suppression strategy and the state space model of the j-th passive broadband oscillation suppression strategy: (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 jth passive broadband oscillation suppression strategy; Step S3: According to 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 positions of the wind turbine converter, the collector line, and the 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: analyzing the change of broadband damping before and after different broadband oscillation suppression strategies are set at different positions; Step S4.2: according to the analysis result of step S4.1, obtaining the broadband damping transfer law when different broadband oscillation suppression strategies are set at different positions; Step S4.3: According to the broadband damping transfer law, select the optimal installation position of different broadband oscillation suppression strategies under the non-target band damping constraint; Step S5: According to the optimal installation position obtained in step S4, the type of the multi-strategy coordinated wide-band oscillation uniform suppression strategy is selected; 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 outlet 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. A multi-strategy coordinated wideband oscillation uniform suppression method for a wind power flexible low-frequency grid-connected system according to claim 2, characterized in that: In step S2: , 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 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 at the outlet side of the wind turbine grid-side converter 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; , where ws_j is the wind turbine speed under the jth 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 jth passive broadband oscillation suppression strategy, udc_j is the DC capacitor voltage of the wind turbine under the jth 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 jth 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 jth passive broadband oscillation suppression strategy, id_j and iq_j are the 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 i-th active broadband oscillation suppression strategy and the j-th passive broadband oscillation suppression strategy and the wind power flexible low-frequency grid-connected system when they are respectively set in the wind turbine converter, the collector line, and the AC converter: (4) (5) (6) In formula (4) to formula (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 circuit, 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, It represents the variable of the voltage interface between the wind power flexible low-frequency grid-connected system 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 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, represents the variable of the current interface between the wind power flexible low-frequency grid-connected system when the i-th active broadband oscillation suppression strategy 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 jth 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 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, 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) to obtain the state space model of the wind power flexible low-frequency grid-connected system set at different locations under different wide-band 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 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 i-th active 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 i-th active 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 in the wind turbine converter, collector line and AC converter respectively for the i-th active broadband oscillation suppression strategy; In formula (8), The state variables 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 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. 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 for the jth passive wide-band oscillation suppression strategy.

5. A multi-strategy coordinated wide-band 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 comprises: 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 of 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 active / passive broadband oscillation suppression strategies at different installation locations: (10) (11) In formula (10) and formula (11), express The increment of express The increment of Step S4.1.3: Solve the state matrix in equation (9) respectively Damping ratio of low frequency band eigenvalue, mid frequency band eigenvalue, and high frequency band eigenvalue , , ; Solve the state matrix in equation (10) respectively Damping ratio of low frequency band eigenvalue, mid frequency band eigenvalue, and high frequency band eigenvalue , , ; Solve the state matrix in equation (11) respectively 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 comprises: After adding the i-th active broadband oscillation suppression strategy, the damping changes in different frequency bands , , The positive and negative signs of make the damping transfer from the frequency band with negative damping change to the frequency band with positive damping change after the i-th active wide-band oscillation suppression strategy is added; 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 comprises: Step S4.3.1: Set the non-target band damping of the i-th active broadband 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 when the wind turbine converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position 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 when the collector line is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 when the AC converter is set under different active broadband oscillation suppression strategies. , if they are all less than, then the position added under each active broadband oscillation suppression strategy is not selected, otherwise, the adding position under an active broadband oscillation suppression strategy corresponding to the maximum damping of the non-target frequency band is selected, which 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 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 , , When it is negative, the corresponding frequency band 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 the value set in the wind turbine converter 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 adding position 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 adding position 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 adding position 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, select the maximum non-target frequency band damping 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 comprises: 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 comprises: 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 selected; (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 wide-band oscillation uniform suppression method described in any one of claims 1 to 9, and the processor is configured to execute the program stored in the memory.

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