A strategy, system and device for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm

Abstract

The present invention discloses a strategy, system, and device for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm. The strategy first utilizes a compaction technique to approximate the projected subspace tracking algorithm to online acquire the frequency and attenuation factor information from the system's subsynchronous oscillation signal. When the acquired attenuation factor reaches a preset threshold, an adaptive notch filter is triggered and applied to the wind turbine rotor-side converter control loop. The adaptive notch filter parameters are adaptively adjusted based on the acquired frequency to block the propagation of the subsynchronous oscillation component, thereby suppressing subsynchronous oscillations. The present invention extracts real-time oscillation information from the system's online operating data, independent of the system's accurate mathematical model. The system requires minimal data, exhibits excellent real-time performance, and possesses strong robustness and adaptability.

Description

Technical Field

[0001] The present invention relates to the technical field of power system control, and in particular to a time-varying subsynchronous oscillation suppression strategy, system and device for a doubly-fed wind farm. Background Art

[0002] Since wind power bases and load centers are "inversely distributed", large-scale, long-distance power transmission is required, so series compensation capacitor technology is widely used in wind power grid-connected systems. However, this also leads to subsynchronous oscillation (SSO) in wind farms caused by the interaction between the doubly fed wind turbine converter and the series compensation capacitor.

[0003] Currently, the addition of subsynchronous damping controllers to doubly-fed wind turbine converters has attracted widespread attention in research on suppressing subsynchronous oscillations in wind farms due to their low cost and ease of control. However, wind farm operation is subject to numerous uncertainties, with significant variations in wind turbine operating conditions and a wide range of time-varying subsynchronous oscillation frequencies. Existing controllers for adding subsynchronous damping only consider a single or a few operating points when designing their control parameters. This makes them unable to adapt to all operating conditions when the system oscillation frequency drifts or when grid operating conditions change significantly. Summary of the Invention

[0004] The present invention aims to provide a strategy, system, and device for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm. This strategy utilizes a compaction technique to approximate a projected subspace tracking algorithm to online acquire the frequency and attenuation factor information from the system's subsynchronous oscillation signal. When the acquired attenuation factor reaches a preset threshold, an adaptive notch filter is triggered and applied to the wind turbine rotor-side converter control loop. The adaptive notch filter parameters are adaptively adjusted based on the acquired frequency to block the propagation of subsynchronous oscillation components, thereby suppressing subsynchronous oscillations. This system extracts real-time oscillation information from the system's online operating data, independent of the system's accurate mathematical model. The system requires minimal data, exhibits excellent real-time performance, and possesses strong robustness and adaptability.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present application proposes a strategy for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm, comprising the following steps:

[0007] The fan outlet current signal is used as the input signal of the subsynchronous oscillation suppression strategy, and the oscillation information in the input signal is obtained by using a compaction technique approximate projected subspace tracking algorithm;

[0008] Extracting subsynchronous oscillation information from the acquired oscillation information; judging the oscillation condition of the system based on the subsynchronous oscillation information; and setting an enabling signal and a center frequency of the adaptive notch filter trigger based on the oscillation condition.

[0009] In some embodiments, the method of using a compaction technique to approximate a projected subspace tracking algorithm to obtain oscillation information in an input signal includes the following steps:

[0010] Define the unconstrained cost function:

[0011]

[0012] Where x(t) is the sampled data vector at time t, W(t) is an m×r matrix, and β∈(0, 1] is the forgetting factor.

[0013] When the cost function reaches the global minimum, we can get sub-matrices W1 and W2, that is,

[0014]

[0015] From this, the signal subspace S can be expressed as:

[0016] S=(W1) + W2 (5)

[0017] By calculating the eigenvalue λ of the signal subspace S k (k=1,2,…,r), we can estimate the frequency and attenuation coefficient of the sinusoidal component in the signal. The frequency and attenuation coefficient of the sinusoidal component are the oscillation information:

[0018]

[0019] Where λ k (k=1,2,…,r) is the eigenvalue of the signal subspace S, f k , τ k are the signal frequency and attenuation coefficient respectively.

[0020] In some embodiments, the condition for extracting the subsynchronous oscillation information from the oscillation information is:

[0021]

[0022] Where, f er is the subsynchronous oscillation frequency.

[0023] In some embodiments, determining the oscillation condition of the system based on the subsynchronous oscillation information specifically includes:

[0024] When the subsynchronous component attenuation coefficient is greater than 0, it is determined that the system is experiencing divergent subsynchronous oscillation;

[0025] When the subsynchronous component attenuation coefficient is less than 0, it is determined that the system has sufficient damping at the corresponding frequency.

[0026] In some embodiments, the step of setting the enabling signal and the center frequency of the adaptive notch filter trigger based on the oscillation condition includes the following steps:

[0027] When it is determined that the system has sufficient damping at the corresponding frequency, there is no need to adjust the enable signal and center frequency of the adaptive notch filter trigger;

[0028] When it is determined that the system has subsynchronous oscillation, the enable signal En is set to 1, an alarm is sent to the control console, and system operation and subsynchronous oscillation information is transmitted. The center frequency of the adaptive notch filter is set to:

[0029] f n =f1-f er (8)

[0030] Where f1 is the system base frequency.

[0031] In some embodiments, the control algorithm of the adaptive notch filter is:

[0032] The adaptive notch filter weight vector update formula is:

[0033] W(k)=W(k-1)+C(k)ξ(k) (9)

[0034] Where W(k) is the weight vector, and the prior estimation error is

[0035] ξ(k)=x(k)-W T (k-1)u(k)

[0036] The gain vector is

[0037]

[0038] The inverse correlation matrix is

[0039] Z(k)=R -1 (k) = λ -1 [Z(k-1)-C(k)u(k)Z(k-1)]

[0040] Where λ∈(0, 1] is the forgetting factor.

[0041] In a second aspect, the present application proposes a doubly-fed wind farm time-varying subsynchronous oscillation suppression system according to any one of the first aspects, characterized in that it includes the following modules:

[0042] Input module: extracts the signal with significant subsynchronous component when subsynchronous oscillation occurs as input signal;

[0043] Oscillation information module: uses the compaction technique to approximate the projected subspace tracking algorithm to obtain the oscillation information in the input signal;

[0044] Oscillation information screening module: extracts subsynchronous oscillation information from oscillation information;

[0045] Identification module: identifies the oscillation status of the system based on subsynchronous oscillation information;

[0046] Adjustment module: sets the enable signal and center frequency of the adaptive notch filter trigger based on the oscillation situation.

[0047] In a third aspect, the present application proposes a terminal device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor. The memory stores a computer program capable of running on the processor. When the processor loads and executes the computer program, it adopts a time-varying subsynchronous oscillation suppression strategy for a doubly fed wind farm as described in any one of the first aspects.

[0048] In a fourth aspect, the present application proposes a computer-readable storage medium, which stores a computer program. When the computer program is loaded and executed by a processor, a time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm as described in any one of the first aspects is adopted.

[0049] Beneficial effects of the present invention:

[0050] The subsynchronous oscillation suppression strategy of the present invention does not rely on the accurate mathematical model of the system, has low algorithm complexity, and is not affected by the accuracy of modeling;

[0051] The subsynchronous oscillation suppression strategy of the present invention obtains real-time system operation data online, has strong self-adaptation capability, and is suitable for wind power systems with large operating state changes.

[0052] The subsynchronous oscillation suppression strategy of the present invention is not put into use in the wind turbine control system when the system does not have subsynchronous oscillation, and does not affect the normal operation control of the wind turbine;

[0053] The subsynchronous oscillation suppression strategy of the present invention requires a small amount of real-time data and a small amount of calculation, has a low cost, and has a high engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention will be further described below with reference to the accompanying drawings.

[0055] Figure 1 This is a control block diagram of the subsynchronous oscillation suppression strategy of the present invention;

[0056] Figure 2 This is a principle block diagram of the adaptive notch filter of the present invention;

[0057] Figure 3 The wind power transmission system of the present invention;

[0058] Figure 4 The suppression effect of the subsynchronous oscillation suppression strategy of the present invention when the system operating state changes at different times;

[0059] Figure 5 The double-fed wind power grid-connected system of the present invention includes wind turbine groups 1 and 2;

[0060] Figure 6 This is the time domain waveform of the active output of the wind turbine group 1 when a large disturbance occurs in the present invention. DETAILED DESCRIPTION

[0061] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0062] A strategy, system, and device for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm, comprising the following steps:

[0063] S1: collecting the fan outlet current signal as the input signal of the subsynchronous oscillation suppression strategy;

[0064] S2: Using the compaction technique to approximate the projected subspace tracking algorithm to obtain the oscillation information in the input signal;

[0065] S3: The subsynchronous oscillation suppression strategy filters the oscillation information obtained in S3 and extracts subsynchronous oscillation information;

[0066] S4: The subsynchronous oscillation suppression strategy determines the system oscillation condition based on the subsynchronous oscillation information extracted in S4;

[0067] S5: The subsynchronous oscillation suppression strategy sets the enable signal and the center frequency of the adaptive notch filter trigger according to the system oscillation situation determined in S5.

[0068] The fan outlet current signal can be expressed as the superposition of several sinusoidal signals with attenuation coefficients and noise, namely:

[0069]

[0070] Where k = 1, 2, ..., r; r is the number of complex sinusoidal components in the sampled signal; T s is the sampling period; B k 、φ k , αk 、f k are the amplitude, initial phase, attenuation coefficient and frequency of the kth sinusoidal component respectively; w is white noise.

[0071] The sampled data vector x(t) at time t is expressed as:

[0072] x(t,m)=[x(t),x(t+1),x(t+2),...,x(t+m-1)] T (2)

[0073] Where, [.] T is the matrix transpose; m is the window length.

[0074] The control strategy block diagram of the present invention is as follows: Figure 1 As shown, it contains two modules: 1) oscillation information estimator of subsynchronous signal; 2) controller for triggering adaptive notch filter

[0075] The purpose of the subsynchronous signal oscillation information estimator is to monitor unstable subsynchronous modes using a compaction technique to approximate the projected subspace tracking algorithm and accurately estimate the subsynchronous oscillation frequency. Define the unconstrained cost function:

[0076]

[0077] Where W(t) is an m×r matrix and β∈(0, 1] is the forgetting factor.

[0078] When the cost function reaches the global minimum, W(t) approaches the eigenvector of the signal subspace S in c(t), thereby estimating the relevant oscillation information in the signal. W(t) is solved iteratively using the recursive least squares method. By deleting the first and last rows of the matrix W(t), we can obtain submatrices W1 and W2, that is,

[0079]

[0080] Therefore, the signal subspace S is expressed as:

[0081] S=(W1) + W2(5)

[0082] Where (.) + is the pseudo-inverse matrix.

[0083] By calculating the eigenvalue λ of the signal subspace S k (k=1,2,…,r), the frequency and attenuation coefficient of the sinusoidal component in the signal can be estimated:

[0084]

[0085] Attenuation coefficient τk The size of τ can be used to intuitively determine the subsynchronous oscillation of the system. k >0 indicates that the system diverges with a frequency of f k Oscillation, τ k <0 indicates that the system has sufficient damping at the corresponding frequency.

[0086] When a fault or disturbance occurs, the system operation data may contain medium and low frequency transients, high frequency noise, supersynchronous components, and fundamental frequency components. Therefore, it is necessary to extract the subsynchronous oscillation signal from the acquired oscillation information. The selection criteria are:

[0087]

[0088] The controller used to trigger the adaptive notch filter sets the adaptive notch filter after monitoring the system operating status. Specifically, when the subsynchronous component attenuation coefficient is detected to be greater than 0 for the first time, it indicates that the system is experiencing divergent subsynchronous oscillation. At this time, the enable signal En needs to be set to 1, and the measured subsynchronous oscillation frequency and enable signal need to be sent to the next module to put the adaptive notch filter into operation. In addition, an alarm needs to be issued to the console, and system operation and subsynchronous oscillation information needs to be reported.

[0089] When the subsynchronous component attenuation coefficient is greater than 0 again, and the current measured frequency exceeds the previously set adaptive notch filter bandwidth BW, that is, |f er -f er ini When |>BW / 2, the secondary synchronization frequency is updated and sent to the next module.

[0090] It's worth noting that when subsynchronous oscillations occur in the system, it indicates an operational problem, such as poor wind farm operating conditions, a grid fault, or a major disturbance. If the adaptive notch filter is deactivated before the operational problem is resolved, unstable subsynchronous oscillations may recur, affecting system stability. Therefore, the adaptive notch filter should be deactivated by the console after the operational problem is resolved, setting its enable signal, En, to 0.

[0091] After detecting system oscillation, set the center frequency of the adaptive notch filter:

[0092] f n =f1-f er (8)

[0093] Where f1 is the system base frequency.

[0094] The principle block diagram of the adaptive notch filter is as follows Figure 2 As shown, it adjusts its own coefficients through an adaptive algorithm to achieve the optimal filtering effect. The specific control algorithm is:

[0095] W(k)=W(k-1)+C(k)ξ(k) (9)

[0096] Where W(k) is the adaptive notch filter weight vector, and the prior estimation error is

[0097] ξ(k)=x(k)-W T (k-1)u(k)

[0098] u(k)=[sin(2πf n k)sin(2πf n k)] T is the reference signal of the adaptive notch filter at time k, and the gain vector is:

[0099]

[0100] The inverse correlation matrix Z(k) is:

[0101] Z(k)=R -1 (k) = λ -1 [Z(k-1)-C(k)u(k)Z(k-1)]

[0102] Where λ∈(0, 1] is the forgetting factor.

[0103] A specific embodiment of the present invention is described below.

[0104] The verification example used in the present invention is a wind power transmission system including a doubly-fed wind farm and series compensation capacitor compensation. The adaptive notch filter is installed at the current comparison item outlet of the doubly-fed wind turbine rotor-side converter. The oscillation information estimator of the sub-synchronous signal collects the wind turbine outlet current as the input signal. The doubly-fed wind farm consists of several identical 1.5MW doubly-fed wind turbines. Each doubly-fed wind turbine is connected to the same busbar through a 0.69 / 35kV on-site step-up transformer T1 for grid-connected power generation. The entire doubly-fed wind farm is simulated using a single-machine equivalent model. The entire wind farm is then connected to the 220kV line through a 35 / 220kV transformer T2, and finally connected to the 500kV line through a 220 / 500kV step-up transformer T3 for long-distance power transmission, and series compensation capacitors are installed in the 500kV line for compensation.

[0105] Example 1:

[0106] Building in MATLAB / SIMULINK Figure 3 The transient simulation model shown in the figure sets the initial operating state of the system to be v wind =7m / s,P output =0.1933pu,Q output =-0.3pu, n = 1000, the system starts to use fixed series compensation (K c=10%), change v at t=10s wind 11m / s, K c is 60%. Then the wind farm active output P output The time domain waveform is as follows Figure 4 shown.

[0107] It can be found that when the 6s and 9s system operating states change, the present invention can promptly and adaptively adjust according to the system oscillation state, thereby quickly and effectively suppressing subsynchronous oscillations. This shows that the present invention's strategy, system, and device for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm have strong adaptive update capabilities and robustness to the situation where the system operating point is constantly changing, enabling it to successfully suppress SSCI triggered by various disturbances every time.

[0108] Example 2:

[0109] During the operation of the system, large disturbances such as machine trips and short circuits are inevitable. Therefore, it is necessary to verify the effect of the subsynchronous oscillation suppression strategy on the suppression of subsynchronous oscillations when large disturbances occur. In the second experimental example, two aggregated wind turbines are used to represent wind turbine groups 1 and 2 under different working conditions. Figure 5 As shown in the figure, the initial speed of wind turbine group 1 is 7m / s, and the speed of wind turbine group 2 is 9m / s. The reactive output of the two wind turbine groups is Q output = 0p.u., number of wind turbines in operation n = 500. Series compensation capacitor (K c =12%) was put into operation at startup. At t = 6s, wind turbine group 2 tripped; and at t = 9s, a three-phase ground short circuit fault occurred on the high-voltage side of T2, and the fault was cleared after 30ms. Without control and under the control of the double-fed wind farm time-varying subsynchronous oscillation suppression strategy, system and device for wind turbine converters of the present invention, the dynamic response waveform of wind turbine group 1 is as follows: Figure 6 shown.

[0110] It can be seen that without additional control, the system waveform begins to oscillate at t=6s and continues to diverge. However, when the doubly-fed wind farm time-varying subsynchronous oscillation suppression strategy, system and device of the present invention are added to the control, the system subsynchronous oscillations caused by the two large disturbances of machine tripping and short-circuit fault can still be successfully suppressed, indicating that the doubly-fed wind farm time-varying subsynchronous oscillation suppression strategy, system and device for wind turbine converters of the present invention are still effective in suppressing oscillations under large disturbances.

[0111] The present application discloses a system for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm, including the following modules:

[0112] Input module: extracts the signal with significant subsynchronous component when subsynchronous oscillation occurs as input signal;

[0113] Oscillation information module: uses the compaction technique to approximate the projected subspace tracking algorithm to obtain the oscillation information in the input signal;

[0114] Oscillation information screening module: extracts subsynchronous oscillation information from oscillation information;

[0115] Identification module: identifies the oscillation status of the system based on subsynchronous oscillation information;

[0116] Adjustment module: sets the enable signal and center frequency of the adaptive notch filter trigger based on the oscillation situation.

[0117] An embodiment of the present application further discloses a terminal device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein when the processor executes the computer program, any one of the time-varying subsynchronous oscillation suppression strategies for a doubly-fed wind farm in the above embodiments is adopted.

[0118] Among them, the terminal device can be a computer device such as a desktop computer, a laptop computer or a cloud server, and the terminal device includes but is not limited to a processor and a memory. For example, the terminal device can also include input and output devices, network access devices and buses, etc.

[0119] Among them, the processor can adopt a central processing unit (CPU). Of course, according to actual usage, other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (SICs for time-varying subsynchronous oscillation suppression in doubly-fed wind farms), ready-made programmable gate arrays (FPGs for time-varying subsynchronous oscillation suppression in doubly-fed wind farms) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. can also be adopted. The general-purpose processor can adopt a microprocessor or any conventional processor, etc., and this application does not impose any restrictions on this.

[0120] Among them, the memory can be an internal storage unit of the terminal device, such as the hard disk or memory of the terminal device, or it can be an external storage device of the terminal device, such as a plug-in hard disk, smart memory card (SMC), secure digital card (SD) or flash memory card (FC) equipped on the terminal device, etc., and the memory can also be a combination of the internal storage unit and the external storage device of the terminal device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory can also be used to temporarily store data that has been output or is to be output. This application does not impose any restrictions on this.

[0121] Among them, through this terminal device, any one of the doubly fed wind farm time-varying subsynchronous oscillation suppression strategies in the above embodiments is stored in the memory of the terminal device, and is loaded and executed on the processor of the terminal device for easy use.

[0122] An embodiment of the present application further discloses a computer-readable storage medium, and the computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, any one of the doubly-fed wind farm time-varying subsynchronous oscillation suppression strategies in the above embodiments is adopted.

[0123] Among them, the computer program can be stored in a computer-readable medium, and the computer program includes computer program code. The computer program code can be in the form of source code, object code, executable file or certain middleware, etc. The computer-readable medium includes any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (R doubly fed wind farm time-varying subsynchronous oscillation suppression M), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the computer-readable medium includes but is not limited to the above-mentioned components.

[0124] Among them, through this computer-readable storage medium, any one of the time-varying subsynchronous oscillation suppression strategies of the doubly fed wind farm in the above embodiments is stored in the computer-readable storage medium, and is loaded and executed on the processor to facilitate the storage and application of the above method.

[0125] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0126] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A strategy for suppressing time-varying subsynchronous oscillations in a doubly-fed wind farm, characterized in that: The steps include: The wind turbine outlet current signal is used as the input signal of the subsynchronous oscillation suppression strategy, and the oscillation information in the input signal is obtained by using a compaction technique approximate projection subspace tracking algorithm; and the subsynchronous oscillation information is extracted from the obtained oscillation information. Determine the oscillation status of the system based on subsynchronous oscillation information; Setting the enable signal and center frequency of the adaptive notch filter trigger based on the oscillation situation; The method of using a compaction technique to approximate a projected subspace tracking algorithm to obtain oscillation information in an input signal comprises the following steps: Define the unconstrained cost function: Where x(t) is the sampled data vector at time t, W(t) is an m×r matrix, and β∈(0,1] is the forgetting factor; When the cost function reaches the global minimum, we get sub-matrices W1 and W2, that is, From this, the signal subspace S can be expressed as: S=(W1) + W2 (5) By calculating the eigenvalue λ of the signal subspace S k (k=1,2,…,r), estimate the frequency and attenuation coefficient of the sinusoidal component in the signal. The frequency and attenuation coefficient of the sinusoidal component are the oscillation information: Where λ k (k=1,2,…,r) is the eigenvalue of the signal subspace S, f k , τ k are the frequency and attenuation coefficient of the signal respectively; The condition for extracting subsynchronous oscillation information from the acquired oscillation information is: Where, f er is the subsynchronous oscillation frequency.

2. The time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm according to claim 1 is characterized in that: The determining the oscillation condition of the system based on the subsynchronous oscillation information specifically includes: When the subsynchronous component attenuation coefficient is greater than 0, it is determined that the system is experiencing divergent subsynchronous oscillation; When the subsynchronous component attenuation coefficient is less than 0, it is determined that the system has sufficient damping at the corresponding frequency.

3. The time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm according to claim 2, characterized in that: The method of setting the enabling signal and the center frequency of the adaptive notch filter trigger based on the oscillation condition includes the following steps: When it is determined that the system has sufficient damping at the corresponding frequency, there is no need to adjust the enable signal and center frequency of the adaptive notch filter trigger; When it is determined that the system has subsynchronous oscillation, the enable signal En is set to 1, an alarm is sent to the control console, and system operation and subsynchronous oscillation information is transmitted. The center frequency of the adaptive notch filter is set to: in n =f1-f er (8) Where f1 is the system base frequency.

4. The time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm according to claim 3 is characterized in that: The control algorithm of the adaptive notch filter is: The adaptive notch filter weight vector update formula is: W(k)=W(k-1)+C(k)ξ(k) (9) Where W(k) is the weight vector, and the prior estimation error is ξ(k)=x(k)-W T (k-1)u(k) The gain vector is: The inverse correlation matrix is: Z(k)=R -1 (k)=λ -1 [Z(k-1)-C(k)u(k)Z(k-1)] Where λ∈(0, 1] is the forgetting factor.

5. A doubly-fed wind farm time-varying subsynchronous oscillation suppression system according to any one of claims 1 to 4, characterized in that: Includes the following modules: Input module: extracts the signal with significant subsynchronous component when subsynchronous oscillation occurs as input signal; Oscillation information module: uses the compaction technique to approximate the projected subspace tracking algorithm to obtain the oscillation information in the input signal; Oscillation information screening module: extracts subsynchronous oscillation information from oscillation information; Identification module: identifies the oscillation status of the system based on subsynchronous oscillation information; Adjustment module: sets the enable signal and center frequency of the adaptive notch filter trigger based on the oscillation situation.

6. A terminal device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: The memory stores a computer program that can be run on the processor. When the processor loads and executes the computer program, the time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm according to any one of claims 1 to 4 is adopted.

7. A computer-readable storage medium storing a computer program, wherein: When the computer program is loaded and executed by the processor, a time-varying subsynchronous oscillation suppression strategy for a doubly-fed wind farm according to any one of claims 1 to 4 is adopted.

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