Active suppression method for shafting oscillation of offshore permanent magnet synchronous wind driven generator

Abstract

The invention discloses an active suppression method for shafting oscillation of an offshore permanent magnet synchronous wind driven generator, which comprises the following steps of: S1, designing an unknown input observer, and observing the rotating speed of the wind driven generator and the torsion angle of a transmission chain under time-varying disturbance on line; s2, designing a sliding mode controller based on an observation result of an unknown input observer, and solving a compensation torque to control the torsion angle of the transmission chain to be stable; and S3, the compensation torque is fed forward to vector control of the permanent magnet synchronous wind driven generator, and the shafting oscillation active suppression system of the permanent magnet synchronous wind driven generator is constructed. According to the method, the defects that an existing method is poor in robustness and high in complexity, and multiple sensors need to be additionally installed are overcome, and shafting oscillation is effectively restrained under the condition that multi-source interference exists in the pneumatic torque of the permanent magnet synchronous wind driven generator.

Description

Technical Field

[0001] The invention relates to the field of motor control, and in particular to a method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine generator. Background Art

[0002] The increasing capacity of offshore wind turbines and the harsh offshore environment will affect the service life of the transmission chain. Therefore, research on reducing the adverse effects of vibration and noise on the transmission chain has high academic research and engineering value. At present, domestic and foreign scholars have summarized three types of vibration reduction technologies based on the process from the source of vibration and noise to the transmission, namely, suppressing the vibration source, optimizing the vibration transmission path, and intervening in the control system.

[0003] The literature (Z.Xu, J.Wei, S.Zhang, Z.Liu, X.Chen, Q.Yan and J.Guo. A state-of-the-art review of the vibration and noise of wind turbine drivetrains [J]. Sustainable Energy Technologies and Assessments, 2021, 48: 1-22) uses a tuned liquid damper based on liquid sway and friction. Experiments have shown that this method effectively enhances structural damping, but since the damper is tuned to a certain oscillation frequency, this will limit its application under a wide excitation frequency. The literature (C.Noyes, C.Qin, E.Loth. Pre-aligned downwind rotor for a 13.2MW wind turbine [J]. Renewable Energy, 2018, 116: 749-754) studied the three-point installation drive system layout, which suppressed the transmission of torque loads in the drive system, but this method is sensitive to non-torque loads. In contrast, the intervention of control systems focuses on reducing vibration and noise through "software" systems rather than "hardware" systems that suppress sources and optimize transmission paths. The classical strategy uses a disturbance observer to estimate target parameters (such as torque deviation and speed deviation), and the inherent oscillation components are filtered out by a bandpass filter and used as feedback to generate additional torque (E. Taherian-Far, R. Sahebi, T. Niknam, A. Izadian, M. Shasadeghi. Wind turbine drivetrain technologies [J]. IEEE Transactions on Industry Applications, 2020, 56 (2): 1729-1741). However, the traditional method has poor robustness under a variety of different operating conditions, and the corresponding controller parameters must be readjusted to restore good damping performance.

[0004] Through the analysis of existing research results, it can be seen that the vibration source suppression method based on additional dampers still has the problem of needing to add additional equipment and difficulty in completely suppressing the vibration source; while the optimization of the vibration transfer path method will cause the system to be sensitive to non-torque loads, and this method usually requires the generation of applicable damping under strong excitation, which also limits its application in offshore wind power scenarios with irregular strong winds. The robustness of the existing control strategy has not yet reached the best, and it is necessary to install additional sensors or use the transmission chain torsion angle that can only be obtained through multiple calculations as the source of response extraction, which also limits its application in some low-cost, compact wind turbine scenarios. Therefore, how to design a control strategy with strong robustness, low cost and excellent performance has become the key to achieving shaft oscillation suppression of offshore permanent magnet synchronous wind turbines. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for actively suppressing shaft oscillations of offshore permanent magnet synchronous wind turbines, so as to overcome the shortcomings of existing methods such as poor robustness, high complexity and the need to install additional sensors, and to achieve effective suppression of shaft oscillations under the condition of multiple sources of interference in the aerodynamic torque of the permanent magnet synchronous wind turbine.

[0006] Technical solution: The method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine described in the present invention comprises the following steps:

[0007] S1. Design an unknown input observer to observe the wind turbine speed and transmission chain torsion angle under time-varying disturbances online;

[0008] S2. Design a sliding mode controller based on the observation results of the unknown input observer to obtain the compensation torque to control the torsion angle stability of the transmission chain;

[0009] S3. Feed forward the compensation torque to the vector control of the permanent magnet synchronous wind turbine generator to construct an active suppression system for the shaft oscillation of the permanent magnet synchronous wind turbine generator; including: subtracting the wind turbine speed given value obtained according to the maximum wind energy capture principle from the actual value, and obtaining the given value of the q-axis current of the wind turbine generator after the error passes through a speed proportional-integral controller, and superimposing it with the q-axis current compensation component output by the sliding mode controller, and after passing through a current proportional-integral controller, outputting a switching signal to drive the permanent magnet synchronous generator.

[0010] Furthermore, the state space equation of the unknown input observer designed in step S1 is:

[0011]

[0012] Among them, z is the auxiliary variable, u is the control input, and y is the system output. is the time derivative of the auxiliary variable, is the observed value of the state variable, and N, G, L, and H are the parameter matrices to be solved.

[0013] Furthermore, the solution method for the parameter matrices N, G, L, and H of the unknown input observer is:

[0014] The wind turbine transmission chain model is expressed as the following state equation form:

[0015]

[0016] Among them, x is the state variable of the wind turbine transmission chain model, is the time derivative of the state variable of the wind turbine transmission chain model; d is the disturbance applied to the aerodynamic torque; A dt , B dt , C dt , D dt are the four parameter matrices in the state equation of the wind turbine transmission chain model;

[0017] The dynamic equation of the state variable observation error e is:

[0018]

[0019] in, is the time derivative of the state variable observation error, P = I + HC dt is the parameter matrix, I is the unit matrix;

[0020] The observed error dynamics are independent of the state of the wind turbine drive train system, control input, and disturbance, and it is concluded that:

[0021]

[0022] G=PB dt

[0023]

[0024] K=L+NH

[0025] Calculate the matrices H and G from the above formula;

[0026] The matrix N needs to satisfy the Hurwitz stability condition and construct the Lyapunov function V 1 =e T Xe, where, e T is the transpose of the observation error e, the matrix X is a positive definite matrix; for the Lyapunov function V 1 Taking the derivative, we get:

[0027]

[0028] in, V 1 The time derivative of ; T represents the matrix transpose; for e T The time derivative of ; parameter matrix

[0029] By solving the matrix X, Get matrices N and L.

[0030] Furthermore, the wind turbine transmission chain model is:

[0031]

[0032] Among them, w R 、w G and θ are wind turbine speed, wind generator speed, and transmission chain torsion angle, respectively; B t , B g are the self-damping coefficients at the wind rotor end and the wind turbine generator end respectively; J t , J g are the rotational inertia of the wind rotor end and the wind turbine generator end respectively; K dt , B dt are the stiffness coefficient and damping coefficient of the transmission chain respectively; η is the transmission efficiency of the transmission chain, N is the reduction ratio of the transmission chain; T classical The aerodynamic torque provided to the wind rotor end, T e The electromagnetic torque provided by the wind turbine generator end, T disturbance is the disturbance applied to the aerodynamic torque.

[0033] Furthermore, the matrix X, The solution is obtained using the LMI toolbox in MATLAB.

[0034] Furthermore, step S2 is specifically as follows:

[0035] When considering the oscillating component, the state space equation of the original system is rewritten as:

[0036]

[0037] Among them, θ is the torsion angle of the transmission chain, w is the speed of the transmission chain, are the oscillation components of θ and w respectively, is the aerodynamic torque T aero The oscillating component of is the electromagnetic torque of the wind turbine generator T e The oscillation component of , J is the equivalent moment of inertia;

[0038] Will The term is expressed as the compensation torque T ecomp and the unmodeled interference function The sum of , where t is time, is:

[0039]

[0040] Design a feedback control law to suppress the transmission chain speed oscillation caused by unknown disturbances Constructing sliding surface Among them, γ is the coefficient of the torsional oscillation component of the transmission chain; construct the Lyapunov function Taking its derivative, we get:

[0041]

[0042] in, Sliding surface s 1 The time derivative of is the Lyapunov function V 2 The time derivative of

[0043] make v is the expression to be determined, the error function Bounded, that is L 1 is the upper bound of the absolute value of the error function, substituting into the above formula:

[0044]

[0045] Select v = -ρsgn(s 1 ), where ρ is the coefficient of the sign function, when ρ>L 1 hour, The compensation torque should be designed as

[0046] Furthermore, step S3 is specifically as follows:

[0047] The wind turbine speed is obtained by using the speed sensor, and the coefficient matrix of the unknown input observer is solved by the LMI toolbox. The wind turbine speed and transmission chain torsion angle are observed based on the unknown input observer.

[0048] A high-pass filter is used to extract the oscillation component of the transmission chain torsion angle. The specific form of the filter transfer function is:

[0049]

[0050] Among them, ω n is the cut-off frequency of the high-pass filter, ζ is the damping coefficient;

[0051] The control input of the sliding mode controller is designed to be the oscillation component of the torsion angle of the transmission chain. The control output is the wind turbine q-axis current compensation component i qcomp* , superimposed on the current control loop given by the wind turbine, and combined with the wind turbine vector control unit, they together form an active suppression system for shaft oscillation of a permanent magnet synchronous wind turbine.

[0052] The above method corresponds to an offshore permanent magnet synchronous wind turbine shaft oscillation active suppression system, comprising:

[0053] Online observation unit, used to design unknown input observer and online observe wind turbine speed and transmission chain torsion angle under time-varying disturbance;

[0054] A compensation torque obtaining unit is used to design a sliding mode controller based on the observation result of the unknown input observer to obtain the compensation torque so as to control the torsion angle stability of the transmission chain;

[0055] A control unit is used to feed forward the compensation torque to the vector control of the permanent magnet synchronous wind turbine generator to construct an active suppression system for the shaft oscillation of the permanent magnet synchronous wind turbine generator; it includes: subtracting the wind turbine speed given value obtained according to the maximum wind energy capture principle from the actual value, and obtaining the given value of the q-axis current of the wind turbine generator after the error passes through the speed proportional integral controller, and superimposing it with the q-axis current compensation component output by the sliding mode controller, and after passing through the current proportional integral controller, outputting a switching signal to drive the permanent magnet synchronous generator.

[0056] An electronic device for storing and executing the above method, the device comprising:

[0057] A memory storing executable program code;

[0058] a processor coupled to the memory;

[0059] The processor calls the executable program code stored in the memory to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine.

[0060] A computer-readable storage medium for storing and executing the above method, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are called, they are used to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine.

[0061] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are: (1) The control scheme has good robustness. When interference is applied, the unknown input observer can still accurately observe the system state variables, and the sliding mode controller can effectively improve the transient performance and steady-state performance of the system and suppress shaft system oscillation; (2) The control scheme has a simple control architecture and does not require complex calculation processes. It is more convenient to execute in digital microprocessors commonly used in actual offshore permanent magnet synchronous wind turbine control systems; (3) The control scheme does not need to be equipped with an electromagnetic torque sensor, but only needs to use a speed sensor to extract the real-time speed of the wind turbine. Active suppression of shaft system oscillation can be achieved without increasing the system software and hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a flow chart of the method of the present invention;

[0063] Figure 2 It is a structural block diagram of the shaft system oscillation active suppression system of the present invention;

[0064] Figure 3 It is the simulation experiment result of the unknown input observer for system state estimation without external disturbance; among them, (a) is the wind turbine speed simulation curve, (b) is the wind generator speed simulation curve, (c) is the transmission chain torsion angle simulation curve; (d) is the wind turbine speed observation error simulation curve; (e) is the wind generator speed observation error simulation curve; (f) is the transmission chain torsion angle observation error simulation curve;

[0065] Figure 4 It is the simulation experiment result of the unknown input observer under the external disturbance of the system state estimation; among them, (a) is the wind turbine speed simulation curve, (b) is the wind generator speed simulation curve, (c) is the transmission chain torsion angle simulation curve; (d) is the wind turbine speed observation error simulation curve; (e) is the wind generator speed observation error simulation curve; (f) is the transmission chain torsion angle observation error simulation curve;

[0066] Figure 5 are the simulation experimental results of the control effect of the sliding mode controller; among them, (a) is the simulation curve of wind turbine speed, (b) is the simulation curve of wind generator speed, and (c) is the simulation curve of transmission chain torsion angle. DETAILED DESCRIPTION

[0067] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0068] like Figure 1 As shown, a method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine of the present invention comprises the following steps:

[0069] S1. Design an unknown input observer (UIO) to observe the wind turbine speed and transmission chain torsion angle under time-varying disturbances online when only the wind turbine speed is known; including:

[0070] Consider the following wind turbine drive train model:

[0071]

[0072] Among them, w R 、w G , θ are wind turbine speed, wind generator speed, and transmission chain torsion angle, respectively; are the time derivative of wind turbine speed, the time derivative of wind generator speed, and the time derivative of transmission chain torsion angle respectively; B t , B g are the self-damping coefficients at the wind rotor end and the wind turbine generator end respectively; J t , J g are the rotational inertia of the wind rotor end and the wind turbine generator end respectively; K dt , B dt are the stiffness coefficient and damping coefficient of the transmission chain respectively; η is the transmission efficiency of the transmission chain, N is the reduction ratio of the transmission chain; T classical The aerodynamic torque provided to the wind rotor end, T e The electromagnetic torque provided by the wind turbine generator end, T disturbance is the disturbance applied to the aerodynamic torque.

[0073] The wind turbine transmission chain model is expressed as the following state equation form:

[0074]

[0075] Among them, x is the state variable of the wind turbine transmission chain model, is the time derivative of the state variable of the wind turbine transmission chain model; y is the system output, and u is the control input; the four parameter matrices in the state equation of the wind turbine transmission chain model can be expressed as C dt =[10 0], d is the vector form of the disturbance applied to the aerodynamic torque.

[0076] The UIO state space equation is designed as follows:

[0077]

[0078] Among them, z is an auxiliary variable, is the time derivative of the auxiliary variable, is the observed value of the state variable, and N, G, L, and H are the parameter matrices to be solved.

[0079] According to equations (2) and (3), the observation error e is obtained as:

[0080]

[0081] Among them, I is the unit matrix, P = I + HC dt is the parameter matrix.

[0082] By taking the derivative of formula (4), we get the dynamic equation of observation error:

[0083]

[0084] in, is the time derivative of the observation error.

[0085] The observed error dynamics are independent of the state of the wind turbine drive train system, control input, and disturbance, so it is concluded that:

[0086]

[0087] The matrix parameter matrices H and G are calculated from the above formula. From formula (5), we can see that the matrix N must satisfy the Hurwitz stability condition. In order to accurately calculate the matrices N and L, construct the Lyapunov function V 1 for:

[0088] V 1 =e T Xe (7)

[0089] Among them, the matrix X is a positive definite matrix, e T is the transpose of the observation error e. For the Lyapunov function V 1 Taking the derivative, we get:

[0090]

[0091] in, V 1 The time derivative of ; T represents the matrix transpose; for e T The time derivative of ; parameter matrix

[0092] By solving the following linear matrix inequality using the LMI toolbox in MATLAB, we can obtain the matrix X,

[0093] Where α is the upper limit of the value of the matrix element to be designed. Solve the matrix X, Then the matrices N and L can be solved by formula (6).

[0094] At this point, all the matrices N, G, L, and H required for the design of UIO have been solved.

[0095] S2. Design a sliding mode controller (SMC) based on the observation results of the unknown input observer to obtain the compensation torque to control the torsion angle stability of the transmission chain; specifically:

[0096] When considering the shaft oscillation component, the state space equation of the wind turbine transmission chain system is rewritten as:

[0097]

[0098] in, They are the oscillation components of θ and w respectively, and w is the time derivative of the transmission chain torsion angle, that is, the transmission chain speed. is the aerodynamic torque T aero The oscillating component of is the electromagnetic torque of the wind turbine generator T e The oscillation component of ; J is the equivalent moment of inertia.

[0099] Will The term is expressed as the compensation torque T ecomp and the unmodeled interference function The sum of , where t is time, is:

[0100]

[0101] Design a feedback control law to suppress the transmission chain speed oscillation component caused by unknown disturbances Construct sliding surface 1 for

[0102]

[0103] Among them, γ is the coefficient of the torsion angle oscillation component of the transmission chain; for the sliding surface s 1 Taking the derivative, we get:

[0104]

[0105] in, is the time derivative of the sliding surface. Construct the Lyapunov function V 2

[0106]

[0107] Taking its derivative, we get:

[0108]

[0109] in, V 2 Time derivative. Let v is the expression to be determined, the error function Bounded, that is L 1 is the upper limit of the absolute value of the error function, substituting into the above formula:

[0110]

[0111] Select v = -ρsgn(s 1 ), where ρ is the coefficient of the sign function, when ρ>L 1 hour, Therefore, the compensation torque should be designed as

[0112] S3. Feed forward the compensation torque to the vector control of the permanent magnet synchronous wind turbine generator to construct an active suppression system for the shaft oscillation of the permanent magnet synchronous wind turbine generator; including: subtracting the wind turbine speed given value obtained according to the maximum wind energy capture principle from the actual value, and obtaining the given value of the q-axis current of the wind turbine generator after the error passes through a speed proportional-integral controller, and superimposing it with the q-axis current compensation component output by the sliding mode controller, and after passing through a current proportional-integral controller, outputting a switching signal to drive the permanent magnet synchronous generator.

[0113] Active suppression system for shaft oscillation of permanent magnet synchronous wind turbine Figure 2 As shown in the figure, the system obtains the optimal wind turbine speed given value under the current wind speed based on the maximum wind power capture (MPPT) principle. The actual value of the wind turbine speed is obtained through the speed sensor, thereby obtaining the deviation value from the target, and this value is used through the speed proportional integral (PI) controller to obtain the given value i of the wind turbine q-axis current. q * , through the current loop to control the wind turbine q axis current i q , thereby controlling the electromagnetic torque T of the wind turbine e , and then further control the wind turbine speed w R In order to suppress the shaft oscillation of the wind turbine, the system uses an unknown input observer (UIO) to observe the transmission chain torsion angle θ and uses a high-pass filter (HPF) to extract the oscillation component of the transmission chain torsion angle Design of appropriate wind turbine q-axis current compensation component i using sliding mode controller (SMC) qcomp * , thereby changing the electromagnetic torque of the wind turbine generator and suppressing the oscillation of the transmission chain system; specifically:

[0114] The wind turbine speed is obtained by using the speed sensor, and the coefficient matrix of the unknown input observer is solved through the LMI toolbox. The wind turbine speed and transmission chain torsion angle are observed based on the unknown input observer.

[0115] A high-pass filter (HPF) is used to extract the oscillation component of the transmission chain torsion angle θ. The specific form of the filter transfer function is:

[0116]

[0117] The cutoff frequency of the high-pass filter is ω n The frequency is set to 3 Hz and the damping coefficient ζ is set to 0.707 to filter out the main DC component of the transmission chain torsion angle.

[0118] The control input of the sliding mode controller is the oscillation component of the torsion angle of the transmission chain The control output is the wind turbine q-axis current compensation component i qcomp * , superimposed on the current control loop of the wind turbine, combined with the wind turbine vector control algorithm, together constitute a permanent magnet synchronous wind turbine shaft oscillation active suppression system.

[0119] The method of the present invention corresponds to an offshore permanent magnet synchronous wind turbine shaft oscillation active suppression system, comprising:

[0120] Online observation unit, used to design unknown input observer and online observe wind turbine speed and transmission chain torsion angle under time-varying disturbance;

[0121] A compensation torque obtaining unit is used to design a sliding mode controller based on the observation result of the unknown input observer to obtain the compensation torque so as to control the torsion angle stability of the transmission chain;

[0122] A control unit is used to feed forward the compensation torque to the vector control of the permanent magnet synchronous wind turbine generator to construct an active suppression system for the shaft oscillation of the permanent magnet synchronous wind turbine generator; it includes: subtracting the wind turbine speed given value obtained according to the maximum wind energy capture principle from the actual value, and obtaining the given value of the q-axis current of the wind turbine generator after the error passes through the speed proportional integral controller, and superimposing it with the q-axis current compensation component output by the sliding mode controller, and after passing through the current proportional integral controller, outputting a switching signal to drive the permanent magnet synchronous generator.

[0123] An electronic device for storing and executing the above method, the device comprising:

[0124] A memory storing executable program code;

[0125] a processor coupled to the memory;

[0126] The processor calls the executable program code stored in the memory to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine.

[0127] A computer-readable storage medium for storing and executing the above method, wherein the computer-readable storage medium stores computer instructions, and when the computer instructions are called, they are used to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine.

[0128] The effectiveness of the active suppression method for shaft oscillation of an offshore permanent magnet synchronous wind turbine proposed in the present invention is verified by MATLAB / Simulink simulation experiments and the simulation experimental results are given;

[0129] In order to demonstrate the proposed control method more clearly, the parameters of the wind turbine, transmission chain and 300kW permanent magnet synchronous wind turbine generator selected in the simulation experiment are as follows:

[0130] ① Wind turbine parameters: impeller radius 14m, air density 1.2kg / m 3 ;

[0131] ② Transmission chain parameters: Low speed side moment of inertia 1800kgm 2 , high speed side moment of inertia 600kgm 2 , transmission chain stiffness coefficient 100000Nm / rad, transmission chain damping coefficient 0Nms / rad, low-speed side self-damping 0Nms / rad, high-speed side self-damping 0Nms / rad, reduction ratio is 1;

[0132] ③Generator parameters: pole pair number is 12, stator resistance is 0.025Ω, d-axis inductance is 3.6mH, q-axis inductance is 3.6mH, permanent magnet flux is 3.89Wb, and DC bus voltage is 1.8kV.

[0133] In the simulation experiment, given a wind speed of 12 m / s, the specific form of disturbance application is classical A negative triangular spike with a maximum amplitude of -10000Nm and a period of 0.03s is added to the unknown input observer. The observation results of the unknown input observer without disturbance and with disturbance are as follows: Figure 3 (a)~(f) and Figure 4 The simulation results show that the unknown input observer can achieve fast convergence of the observed value, and its observation error is within 2×10 -4 rad, the observation performance is excellent. The control effect of the sliding mode controller is as follows Figure 5As shown in (a), (b), and (c), it can be seen from the figure that although the addition of SMC will produce a small vibration in the steady-state speed of the motor, the oscillation amplitude of the transmission chain torsion angle is effectively attenuated compared to when no control is added, which proves that the proposed SMC achieves the improvement of the steady-state performance of the system. In addition, the adjustment time of the system is about 3.5s when no control is taken, and the adjustment time of the system is about 2.6s after adding SMC control, which proves that the proposed SMC improves the transient performance of the system. In summary, the unknown input observer designed in the present invention can realize the accurate observation of the speed and the transmission chain torsion angle, and the designed sliding mode controller can effectively improve the transient and steady-state performance of the wind turbine system and suppress the torsional vibration of the permanent magnet synchronous wind turbine transmission chain.

Claims

1. A method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine, characterized in that: The following steps are involved: S1. Design an unknown input observer to observe the wind turbine speed and transmission chain torsion angle under time-varying disturbances online; S2. Design a sliding mode controller based on the observation results of the unknown input observer to obtain the compensation torque to control the torsion angle stability of the transmission chain; S3. Feed forward the compensation torque to the vector control of the permanent magnet synchronous wind turbine generator to construct an active suppression system for the shaft oscillation of the permanent magnet synchronous wind turbine generator; including: subtracting the wind turbine speed given value obtained according to the maximum wind energy capture principle from the actual value, and obtaining the given value of the q-axis current of the wind turbine generator after the error passes through a speed proportional-integral controller, and superimposing it with the q-axis current compensation component output by the sliding mode controller, and after passing through a current proportional-integral controller, outputting a switching signal to drive the permanent magnet synchronous generator.

2. A method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 1, characterized in that: The state space equation of the unknown input observer designed in step S1 is: Among them, z is the auxiliary variable, u is the control input, and y is the system output. is the time derivative of the auxiliary variable, is the observed value of the state variable, and N, G, L, and H are the parameter matrices to be solved.

3. A method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 2, characterized in that: The solution method for the parameter matrices N, G, L, and H of the unknown input observer is: The wind turbine transmission chain model is expressed as the following state equation form: Among them, x is the state variable of the wind turbine transmission chain model, is the time derivative of the state variable of the wind turbine transmission chain model; d is the disturbance applied to the aerodynamic torque; A dt , B dt , C dt , D dt are the four parameter matrices in the state equation of the wind turbine transmission chain model; The dynamic equation of the state variable observation error e is: in, is the time derivative of the state variable observation error, P = I + HC dt is the parameter matrix, I is the unit matrix; The observed error dynamics are independent of the state of the wind turbine drive train system, control input, and disturbance, and it is concluded that: G=PB dt K=L+NH Calculate the matrices H and G from the above formula; The matrix N needs to satisfy the Hurwitz stability condition and construct the Lyapunov function V1=e T Xe, where, e T is the transpose of the observation error e, and the matrix X is a positive definite matrix; taking the derivative of the Lyapunov function V1, we get: in, is the time derivative of V1; T represents matrix transpose; for e T The time derivative of ; parameter matrix By solving the matrix X, Get matrices N and L.

4. A method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 3, characterized in that: The wind turbine transmission chain model is: Among them, w R 、w G and θ are wind turbine speed, wind generator speed, and transmission chain torsion angle, respectively; B t , B g are the self-damping coefficients at the wind rotor end and the wind turbine generator end respectively; J t , J g are the rotational inertia of the wind rotor end and the wind turbine generator end respectively; K dt , B dt are the stiffness coefficient and damping coefficient of the transmission chain respectively; η is the transmission efficiency of the transmission chain, N is the reduction ratio of the transmission chain; T classical The aerodynamic torque provided to the wind rotor end, T e The electromagnetic torque provided by the wind turbine generator end, T disturbance is the disturbance applied to the aerodynamic torque.

5. The method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 3, characterized in that: Matrix X, The solution is obtained using the LMI toolbox in MATLAB.

6. The method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 1, characterized in that: Step S2 is specifically as follows: When considering the oscillating component, the state space equation of the original system is rewritten as: Among them, θ is the transmission chain torsion angle, w is the transmission chain speed, are the oscillation components of θ and w respectively, is the aerodynamic torque T aero The oscillating component of is the electromagnetic torque of the wind turbine generator T e The oscillation component of , J is the equivalent moment of inertia; Will The term is expressed as the compensation torque T ecomp and the unmodeled interference function The sum of , where t is time, is: Design a feedback control law to suppress the transmission chain speed oscillation caused by unknown disturbances Constructing sliding surface Among them, γ is the coefficient of the torsional oscillation component of the transmission chain; construct the Lyapunov function Taking its derivative, we get: in, is the time derivative of the sliding surface s1, is the time derivative of the Lyapunov function V2; make v is the expression to be determined, the error function Bounded, that is L1 is the upper bound of the absolute value of the error function. Substituting it into the above formula, we get: Select υ=-ρsgn(s1), where ρ is the coefficient of the sign function. When ρ>L1, The compensation torque should be designed as 7. The method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine according to claim 1, characterized in that: Step S3 is specifically as follows: The wind turbine speed is obtained by using the speed sensor, and the coefficient matrix of the unknown input observer is solved by the LMI toolbox. The wind turbine speed and transmission chain torsion angle are observed based on the unknown input observer. A high-pass filter is used to extract the oscillation component of the transmission chain torsion angle. The specific form of the filter transfer function is: Among them, ω n is the cut-off frequency of the high-pass filter, ζ is the damping coefficient; The control input of the sliding mode controller is designed to be the oscillation component of the torsion angle of the transmission chain. The control output is the wind turbine q-axis current compensation component i qcomp * , superimposed on the current control loop given by the wind turbine, and combined with the wind turbine vector control unit, they together form an active suppression system for shaft oscillation of a permanent magnet synchronous wind turbine.

8. An active suppression system for shaft oscillation of an offshore permanent magnet synchronous wind turbine, characterized in that: include: Online observation unit, used to design unknown input observer and online observe wind turbine speed and transmission chain torsion angle under time-varying disturbance; A compensation torque obtaining unit is used to design a sliding mode controller based on the observation result of the unknown input observer to obtain the compensation torque so as to control the torsion angle stability of the transmission chain; A control unit is used to construct an active suppression system for shaft oscillation of a permanent magnet synchronous wind turbine generator and to perform vector control on the permanent magnet synchronous wind turbine generator, including: subtracting a given value of the wind turbine speed obtained according to the maximum wind energy capture principle from an actual value, and obtaining a given value of the q-axis current of the wind turbine generator after the error passes through a speed proportional-integral controller, and superimposing it with the q-axis current compensation component output by a sliding mode controller, and after passing through a current proportional-integral controller, outputting a switch signal to drive the permanent magnet synchronous generator.

9. An electronic device, characterized in that: The device comprises: A memory storing executable program code; a processor coupled to the memory; The processor calls the executable program code stored in the memory to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, which, when called, are used to execute the steps of the method for actively suppressing shaft oscillation of an offshore permanent magnet synchronous wind turbine as described in any one of claims 1 to 7.

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