阅读说明：本技术 一种风电机组传动链扭振附加阻尼控制方法 (Wind turbine generator set transmission chain torsional vibration additional damping control method ) 是由 吴仟 孙勇 王瑞良 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种风电机组传动链扭振附加阻尼控制方法,考虑风电机组传动链扭振特性及运行安全性,建立了轴系两质量块模型下速度环的状态空间方程,采用卡尔曼滤波观测器对传动链扭转角速度进行估计,有效地解决了实际系统中信号测量难题。对传动链扭转角速度进行滤波、信号放大、限幅后得到与传动链扭转速度相反的扰动转矩,附加到风电机组控制系统的给定转矩值上。该方法不仅能避开风轮转速的多阶穿越频率,而且能增大传动链系统的等效阻尼,实现传动链扭振抑制目的。(The invention discloses a control method for torsional vibration additional damping of a transmission chain of a wind turbine generator, which considers torsional vibration characteristics and operation safety of the transmission chain of the wind turbine generator, establishes a state space equation of a speed ring under two mass block models of a shafting, adopts a Kalman filtering observer to estimate the torsional angular speed of the transmission chain, and effectively solves the problem of signal measurement in an actual system. And filtering, signal amplifying and amplitude limiting the torsional angular speed of the transmission chain to obtain a disturbance torque opposite to the torsional speed of the transmission chain, and adding the disturbance torque to a given torque value of a control system of the wind turbine generator. The method not only can avoid the multi-order crossing frequency of the rotating speed of the wind wheel, but also can increase the equivalent damping of the transmission chain system, and achieves the purpose of suppressing the torsional vibration of the transmission chain.)

1. A wind turbine generator transmission chain torsional vibration additional damping control method is characterized by comprising the following steps:

s1, constructing a state space equation of the speed ring under the two-mass-block model of the shafting by combining the two-mass-block model of the shafting of the wind turbine generator and the closed-loop control structure of the speed ring;

s2 discretizing the state space equation of the speed ring under the shafting two-mass block model, and utilizing a Kalman filtering observer to carry out transmission chain torsion angular velocityPredicting to obtain the optimal state estimation value

S3, carrying out notch filtering on the obtained torsion angle of the transmission chain to obtain a filtering torsion angular velocity;

s4, band-pass filtering and signal amplifying are carried out on the filtering torsion angular velocity in the step 3, and a disturbance torque T opposite to the torsion velocity of the transmission chain is obtained_d；

S5 wind turbine generator control systemAdding disturbance torque T to statistically calculated given torque value_dAnd performs torque increment limitation on this.

2. The wind turbine generator transmission chain torsional vibration additional damping control method according to claim 1, wherein the step S1 is used for constructing a state space equation of a speed ring under a shafting two-mass-block model

The construction process specifically comprises the following steps:

s1.1 simplifying the current loop as a proportional link 1, electromagnetic torque instruction valueFor setting the speedDifference with velocity feedback, introducing state variablesElectromagnetic torque T after speed PI closed-loop control_gCan be expressed as:

wherein K_p、K_iRespectively, the proportional and integral coefficients of the outer ring of the speed;

s1.2, two mass block models are adopted to describe the dynamic characteristics of a wind wheel and a low-speed shaft, and the torsional transmission of a transmission chain is expressed by a mathematical formula as follows:

wherein J_r、J_gIs the rotational inertia of wind wheel and generator, T_r、ω_rAs wind wheel torque, angular velocity, K_cTo system equivalent stiffness, D_eIs the coefficient of damping viscosity, θ, of the system_sIs the drive chain twist angle;

s1.3, combining the two-mass-block model of the shafting of the wind turbine generator and a speed ring closed-loop control structure, the state space expression of the speed ring under the two-mass-block model of the shafting can be expressed as follows:

3. the wind turbine generator transmission chain torsional vibration additional damping control method according to claim 1, wherein the optimal state estimation value is performed in step S2The method comprises the following steps:

s2.1, discretizing the state space equation A, B coefficient matrix in the step S1 to obtain:

wherein I is a unit matrix, and T is sampling time;

s2.2, assuming that the measurement noise and the process noise are random quantities and the mean value is 0, the discretization form of the state space equation is as follows:

s2.3, the discretization difference equation is processed to obtain a corresponding state prediction equationError covariancePrediction equation P_k|k-1Kalman gain equation K_kState estimation correction equationError covariance estimation correction equation P_k|kThe concrete form is as follows:

P_k|k-1＝MP_k-1|k-1M^T+Q

K_k＝P_k|k-1C^T(CP_k-1|k-1C^T+R)^-1

P_k|k＝(I-K_kC)P_k|k-1

r, Q are the covariance of the measurement noise and the process noise, respectively;

s2.4, after the wind wheel rotating speed estimated value and the generator rotating speed estimated value are obtained according to the Kalman filtering observer, the transmission system torsional angular speed estimated value

4. The wind turbine generator transmission chain torsional vibration additional damping control method according to claim 1, wherein the step S3 is used for avoiding the multi-order crossing frequency of the wind turbine rotation speed, and the expression form of the notch filter is as follows:

wherein, ω is₁、ω₂Is angular frequency, ξ₁、ξ₂Is the damping ratio.

5. The method for controlling the torsional vibration additional damping of the transmission chain of the wind turbine generator set according to claim 1, wherein the band-pass filter in the step S4 is expressed as follows:

where K is the gain, ω₃Is angular frequency, ξ_fIs the damping ratio.

6. The wind turbine generator transmission chain torsional vibration additional damping control method according to claim 1, wherein step S5 is performed to limit the generator torque variation range to be too large, so as to increase the equivalent damping of the transmission chain system and achieve the purpose of suppressing the transmission chain torsional vibration.

Technical Field

The invention relates to the technical field of wind turbine generators, in particular to a method for controlling torsional vibration additional damping of a transmission chain of a wind turbine generator.

Background

Along with the increasing of the capacity of the wind turbine generator, the flexibility of a transmission chain of the generator is increased, the damping is reduced, the coupling probability of each mode is increased, the influence of dynamic load on the transmission chain of the generator is increased, the torsional vibration problem of the transmission chain is more and more prominent, the actual service life of the generator and the economic benefit of a wind power plant are seriously influenced, and therefore the increasing of the damping for the transmission chain is very important for improving the performance of the generator.

Aiming at the problem of torsional vibration of a transmission chain, the research at home and abroad mainly proceeds from two aspects of mechanical control and electrical control. And (5) researching active damping control of the traveling transmission chain. In the aspect of mechanical control, shock insulation or energy consumption devices are artificially installed at certain parts of the unit, so that the mechanical damping of the system is increased; from an electrical control perspective, damping may be provided by appropriate modification of the torque control of the generator. Because of the high cost of mechanical control, electrical damping control is still the mainstream at present.

In an actual wind turbine generator system, an electrical damping control method is adopted, a sensor is required to acquire the rotating speed of a wind wheel and the rotating speed of a generator to acquire the torsional angular velocity, but the rotating speed of the wind wheel is usually low, and the resolution and accuracy of a low-speed shaft sensor are possibly deficient, so that the rotating speeds of the wind wheel and the generator cannot be acquired at the same time, and the torsional angular velocity cannot be directly acquired, so that a proper observer is added in a transmission chain torsional vibration control link, and the state quantity required by torsional vibration control is effectively estimated. Meanwhile, the avoidance of multi-order crossing frequency is considered, and the filtering processing of the state estimator is also necessary.

Chinese patent document CN109657320A discloses a "wind turbine generator transmission chain modeling and torsional vibration characteristic analysis method". The modeling and analyzing method comprises the following steps: firstly: establishing a drive chain dynamic model, which comprises the following steps: a transmission chain three-dimensional entity model and a transmission chain finite element model; and secondly, carrying out simulation analysis on the transmission chain finite element model, and carrying out post-processing on a simulation result. The invention overcomes the defect that the existing mass block model can only extract individual torsional vibration frequency, and avoids the frequency loss caused by simplifying the flexibility of parts; meanwhile, the torsional vibration of the transmission chain can be clearly judged in a pattern form, so that the torsional vibration characteristic of the transmission chain can be quantitatively analyzed.

Disclosure of Invention

The invention mainly solves the technical problems of high cost and inconvenient rotating speed acquisition of the transmission chain torsional vibration control realized by the original technical scheme, provides the additional damping control method for the wind turbine transmission chain torsional vibration, considers the torsional vibration characteristics and the operation safety of the wind turbine transmission chain, establishes a state space equation of a speed ring under two mass block models of a shafting, adopts a Kalman filtering observer to estimate the angular speed of the transmission chain torsion, and effectively solves the signal measurement problem in an actual system. And filtering, signal amplifying and amplitude limiting the torsional angular speed of the transmission chain to obtain a disturbance torque opposite to the torsional speed of the transmission chain, and adding the disturbance torque to a given torque value of a control system of the wind turbine generator. The method not only can avoid the multi-order crossing frequency of the rotating speed of the wind wheel, but also can increase the equivalent damping of the transmission chain system, and achieves the purpose of suppressing the torsional vibration of the transmission chain.

The technical problem of the invention is mainly solved by the following technical scheme: the invention comprises the following steps:

s1, constructing a state space equation of the speed ring under the two-mass-block model of the shafting by combining the two-mass-block model of the shafting of the wind turbine generator and the closed-loop control structure of the speed ring;

s2 discretizing the state space equation of the speed ring under the shafting two-mass block model, and utilizing a Kalman filtering observer to carry out transmission chain torsion angular velocityPredicting to obtain the optimal state estimation value

S3, carrying out notch filtering on the obtained torsion angle of the transmission chain to obtain a filtering torsion angular velocity;

s4, band-pass filtering and signal amplifying are carried out on the filtering torsion angular velocity in the step 3, and a disturbance torque T opposite to the torsion velocity of the transmission chain is obtained_d；

S5 adding disturbance torque T to the given torque value calculated by the wind turbine control system_dAnd performs torque increment limitation on this.

Preferably, the step S1 is to construct a state space equation of the velocity ring under the shafting two-mass-block model

The construction process specifically comprises the following steps:

s1.1 simplifying the current loop as a proportional link 1, electromagnetic torque instruction valueFor setting the speedDifference with velocity feedback, introducing state variablesElectromagnetic torque T after speed PI closed-loop control_gCan be expressed as:

wherein K_p、K_iRespectively, the proportional and integral coefficients of the outer ring of the speed;

s1.2, two mass block models are adopted to describe the dynamic characteristics of a wind wheel and a low-speed shaft, and the torsional transmission of a transmission chain is expressed by a mathematical formula as follows:

wherein J_r、J_gIs the rotational inertia of wind wheel and generator, T_r、ω_rAs wind wheel torque, angular velocity, K_cTo system equivalent stiffness, D_eIs the coefficient of damping viscosity, θ, of the system_sIs the drive chain twist angle;

s1.3, combining the two-mass-block model of the shafting of the wind turbine generator and a speed ring closed-loop control structure, the state space expression of the speed ring under the two-mass-block model of the shafting can be expressed as follows:

as a preference, the first and second liquid crystal compositions are,the step S2 performs the optimum state estimationThe method comprises the following steps:

s2.1, discretizing the state space equation A, B coefficient matrix in the step S1 to obtain:

wherein I is a unit matrix, and T is sampling time;

s2.2, assuming that the measurement noise and the process noise are random quantities and the mean value is 0, the discretization form of the state space equation is as follows:

s2.3, the discretization difference equation is processed to obtain a corresponding state prediction equationError covariance prediction equation P_k|k-1Kalman gain equation K_kState estimation correction equationError covariance estimation correction equation P_k|kThe concrete form is as follows:

P_k|k-1＝MP_k-1|k-1M^T+Q

K_k＝P_k|k-1C^T(CP_k-1|k-1C^T+R)^-1

P_k|k＝(I-K_kC)P_k|k-1

r, Q are the covariance of the measurement noise and the process noise, respectively;

s2.4, after the wind wheel rotating speed estimated value and the generator rotating speed estimated value are obtained according to the Kalman filtering observer, the transmission system torsional angular speed estimated value

Preferably, the step S3 is to avoid the multiple-step crossover frequency of the rotor speed, and the expression form of the notch filter is as follows:

wherein, ω is₁、ω₂Is angular frequency, ξ₁、ξ₂Is the damping ratio.

Preferably, in step S4, the band-pass filter is expressed as follows:

where K is the gain, ω₃Is angular frequency, ξ_fIs the damping ratio.

Preferably, step S5 is to limit the generator torque variation range to be too large, so as to increase the equivalent damping of the drive train system and achieve the purpose of suppressing the torsional vibration of the drive train.

The invention has the beneficial effects that: the torsional vibration characteristic and the operation safety of the transmission chain of the wind turbine generator are considered, a state space equation of a speed ring under a two-mass-block model of a shafting is established, a Kalman filter observer is adopted to estimate the torsional angular speed of the transmission chain, and the signal measurement problem in an actual system is effectively solved. And filtering, signal amplifying and amplitude limiting the torsional angular speed of the transmission chain to obtain a disturbance torque opposite to the torsional speed of the transmission chain, and adding the disturbance torque to a given torque value of a control system of the wind turbine generator. The method not only can avoid the multi-order crossing frequency of the rotating speed of the wind wheel, but also can increase the equivalent damping of the transmission chain system, and achieves the purpose of suppressing the torsional vibration of the transmission chain.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a frequency characteristic diagram of a notch filter of the present invention.

FIG. 3 is a structural diagram of additional damping control for torsional vibration of a wind turbine generator according to the present invention.

FIG. 4 is a graph comparing the dynamic response of a wind turbine system incorporating additional damping control of the drive train with no damping control in case of turbulent wind according to the present invention.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings. Example (b): the method for controlling the torsional vibration additional damping of the transmission chain of the wind turbine generator set in the embodiment is shown in fig. 1 and comprises the following steps:

s1, combining the two-mass-block model of the wind turbine shafting and the closed-loop control structure of the speed ring to construct the state space equation of the speed ring under the two-mass-block model of the shafting.

The construction process specifically comprises the following steps:

s1.1 simplifying the current loop as a proportional link 1, electromagnetic torque instruction valueFor setting the speedDifference with velocity feedback, introducing state variablesElectromagnetic torque T after speed PI closed-loop control_gCan be expressed as:

wherein K_p、K_iRespectively, the proportional and integral coefficients of the outer ring of the speed;

s1.2, two mass block models are adopted to describe the dynamic characteristics of a wind wheel and a low-speed shaft, and the torsional transmission of a transmission chain is expressed by a mathematical formula as follows:

wherein J_r、J_gIs the rotational inertia of wind wheel and generator, T_r、ω_rAs wind wheel torque, angular velocity, K_cTo system equivalent stiffness, D_eIs the coefficient of damping viscosity, θ, of the system_sIs the drive chain twist angle;

s1.3, combining the two-mass-block model of the shafting of the wind turbine generator and a speed ring closed-loop control structure, the state space expression of the speed ring under the two-mass-block model of the shafting can be expressed as follows:

s2 discretizing the state space equation of the speed ring under the shafting two-mass block model, and utilizing a Kalman filtering observer to carry out transmission chain torsion angular velocityPredicting to obtain the optimal state estimation valueThe method comprises the following steps:

s2.1, discretizing the state space equation A, B coefficient matrix in the step S1 to obtain:

wherein I is a unit matrix, and T is sampling time;

s2.2, assuming that the measurement noise and the process noise are random quantities and the mean value is 0, the discretization form of the state space equation is as follows:

s2.3, the discretization difference equation is processed to obtain a corresponding state prediction equationError covariance prediction equation P_k|k-1Kalman gain equation K_kState estimation correction equationError covariance estimation correction equation P_k|kThe concrete form is as follows:

P_k|k-1＝MP_k-1|k-1M^T+Q

K_k＝P_k|k-1C^T(CP_k-1|k-1C^T+R)^-1

P_k|k＝(I-K_kC)P_k|k-1

r, Q are the covariance of the measurement noise and the process noise, respectively;

s2.4, after the wind wheel rotating speed estimated value and the generator rotating speed estimated value are obtained according to the Kalman filtering observer, the torsional angular speed of the transmission system is estimatedValue ofS3, the notch filter is used for avoiding the multi-order crossing frequency of the wind wheel rotating speed, and carrying out notch filtering on the obtained torsion angle of the transmission chain to obtain the filtering torsion angular speed, and the expression form of the notch filter is as follows:

wherein, ω is₁、ω₂Is angular frequency, ξ₁、ξ₂Is the damping ratio.

S4, band-pass filtering and signal amplifying are carried out on the filtering torsion angular velocity in the step 3, and a disturbance torque T opposite to the torsion velocity of the transmission chain is obtained_dThe band pass filter is expressed as follows:

where K is the gain, ω₃Is angular frequency, ξ_fIs the damping ratio.

S5 adding disturbance torque T to the given torque value calculated by the wind turbine control system_dAnd carrying out torque increment amplitude limiting on the transmission chain, limiting the torque variation range of the generator to be overlarge, and finally achieving the purposes of increasing the equivalent damping of the transmission chain system and restraining the torsional vibration of the transmission chain.

In the embodiment, a WD131-2200 (wind wheel diameter 131m and power 2200kw) double-fed model is selected to test the invention, the cut-in wind speed of the model is 3m/s, the cut-out wind speed is 20m/s, and the optimal pitch angle is 0 degree.

The simulation test is carried out by industrial simulation software Bladed, and the specific steps are as follows:

step 1: and establishing a state space equation of the speed ring under the shafting two-mass block model. In this example, K_p＝480.5，K_i＝153.7，J_r＝1484.98，J_g＝129.92，D_e＝0.00608，K_c＝0.0001；

Step 2: discretizing the state space equation, and utilizing a Kalman filtering observer to carry out torsional angular velocity on the transmission chainAnd (6) forecasting to obtain an optimal state estimation value by continuously adjusting R, Q covariance. In this embodiment, considering that the system noise is much larger than the measurement noise, let R ═ 0.0001]，Q＝[10¹²]；

And step 3: in order to avoid the multi-order crossing frequency of the rotating speed of the wind wheel, the obtained torsion angle of the transmission chain is subjected to notch filtering, and the filtering torsion angular speed is obtained. In this embodiment, ω₁＝7.97，ξ₁＝0.1，ω₂＝7.97，ξ₂0.45, the frequency characteristic is shown in fig. 2;

and 4, step 4: performing band-pass filtering and signal amplification on the filtering torsional angular velocity in the step 3 to obtain a disturbance torque T opposite to the torsional velocity of the transmission chain_dIn this embodiment, K is 525.38, ω₃＝8.6536,ξ_f＝0.50789；

And 5: adding T to a given torque value calculated by a wind turbine control system_dAnd performing torque increment amplitude limiting on the torque increment to limit the torque variation range of the generator to be overlarge, wherein the transmission chain torsional vibration suppression structure is shown in a figure 3. In an embodiment, the clipping values are ± 600 Nm/s.

In the present embodiment, turbulent wind with an average wind speed of 12m/s is set, and the turbulence intensities in the three degrees of freedom are 5, 4, and 2.5, respectively. As can be seen from fig. 4, where (a) wind speed, (b) generator torque, (c) output power, and (d) rotating hub Mx load, at the same turbulent wind conditions at 40 s-70 s, the generator torque fluctuation amplitude in the additional damping control strategy is larger and the generator speed is smoother compared to undamped control, due to the additional torque being directly superimposed on the torque setpoint. But it can be seen from the load of the rotary hub Mx direction that the fluctuation amplitude is obviously smaller than that of the undamped control, and the dynamic load of the transmission chain is effectively smaller. Therefore, the transmission chain torsional vibration additional damping control strategy can increase the equivalent damping of a transmission chain system and realize the effective inhibition of the dynamic load of the transmission chain.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although terms such as two-mass model of wind turbine shafting, closed-loop control structure of speed ring, etc. are used more frequently herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.