A method and device for evaluating and suppressing shaft torsional vibration of a network-constructed doubly-fed wind turbine based on dissipated energy

Abstract

The application discloses a network-constructing type doubly-fed wind turbine shaft torsional vibration damping evaluation-inhibition method and device based on dissipated energy, and relates to the technical field of power system damping control. The method first acquires unit operation electrical quantity data, judges whether shaft torsional vibration occurs or not; if the shaft torsional vibration occurs, the data is preprocessed, the shaft dissipated energy is calculated, the energy dissipation factor is obtained through Hilbert transform and normalization, and the damping size and property are evaluated; then, the damping controller compensation angle is determined by using the measured data, the parameter of a phase shifter is set by using the residue method, the controller gain is adaptively adjusted according to the energy dissipation factor, and the controller is put into operation as needed to inhibit the torsional vibration. The method can effectively improve the shaft torsional vibration damping, inhibit the torsional vibration phenomenon, adapt to the weak damping and negative damping scene, and guarantee the stable operation of a power system containing the network-constructing type doubly-fed wind turbine.

Description

Technical Field

[0001] This invention relates to the field of power system damping control technology, and in particular to a method and apparatus for evaluating and suppressing shaft torsional vibration damping of grid-type doubly fed wind turbine generators based on dissipated energy. Background Technology

[0002] Driven by resource crises and environmental issues, the global transformation towards new energy power generation continues to deepen, accelerating the decarbonization of the power structure. With the continuous improvement of wind power technology and the increasing capacity of wind turbine generators, more and more wind farms are being put into operation, leading to a continuous expansion of wind energy's share in the power grid. Doubly fed induction generators (DFIGs) are currently the mainstream model used in grid-connected wind farms.

[0003] In high-proportion wind power grid-connected systems, conventional synchronous generators are largely replaced by wind turbine generators, leading to a decrease in system frequency and voltage regulation capabilities. Voltage source doubly-fed induction generators (DFIGs) possess the ability to actively support frequency and voltage, providing crucial equipment support for the realization of new power systems and showing promising application prospects. The characteristic of VSG (Virtual Synchronous Generator) control is that it simulates the rotor motion equations of a synchronous generator, giving the converter inertia and damping characteristics. Grid-type DFIGs using VSG control take the amplitude and phase of the stator voltage as control targets, making them exhibit voltage source characteristics. This not only provides good active and reactive power tracking performance but also provides inertia and damping to the system, improving system stability.

[0004] Grid-connected doubly-fed induction generator (DFIG) wind turbines involve a cascaded multi-physical structure encompassing aerodynamics, mechanics, and electrical components. Considering the flexibility of control bandwidth and strong interaction with the power grid, the oscillation modes of the mechanical structure pose a risk of inducing system-level electromechanical oscillations. Shaft torsional vibration not only threatens the safety and stability of the power system but also damages its own mechanical components, thus affecting the overall lifespan of the unit. When DFIGs employ VSG control, the shaft torsional vibration problem undergoes profound changes, even reshaping itself. Therefore, suppressing shaft torsional vibration is particularly urgent to ensure the reliability of grid-connected DFIG systems.

[0005] Application content

[0006] To address the above problems, this invention discloses a method for evaluating and suppressing torsional vibration damping of the shaft system in a grid-type doubly-fed wind turbine based on dissipated energy, comprising the following steps:

[0007] Step 1: Obtain data of various electrical quantities during the operation of the doubly-fed wind turbine. The electrical quantities include data of each electrical quantity at the steady-state operating point and data when oscillation occurs. Based on the data of various electrical quantities during the operation of the doubly-fed wind turbine, determine whether shaft torsional vibration has occurred.

[0008] Step 2: When torsional vibration occurs, the electrical quantity data of each generator in the system are preprocessed to obtain the change of each electrical quantity relative to the steady-state value.

[0009] Step 3: Calculate the dissipated energy ΔW of the shaft system using the changes of each electrical quantity relative to its steady-state value. H The calculation formula is:

[0010] ΔW H =∫ΔT r dΔθ r -D sh ∫(Δω r -Δω g ) 2 dt-∫ΔT e dΔθ g

[0011] Wherein, ΔW H T represents the dissipated energy of the shaft system. r For the mechanical torque of the wind turbine; Δθ r D represents the change in the wind turbine's rotation angle relative to its steady-state value. sh Here, Δω represents the shaft system stiffness coefficient and shaft system damping coefficient. r Δω represents the change in wind turbine speed relative to its steady-state value. g T represents the change in generator speed relative to its steady-state value. e For the electromagnetic torque of the generator; Δθ g The change in generator rotation angle relative to its steady-state value; the subscript 0 indicates the steady-state value of the corresponding variable.

[0012] Step 4: The dissipated energy ΔW H Perform a Hilbert transform to obtain the upper envelope of the dissipated energy. Then, perform Z-score normalization on the upper envelope to obtain the normalized upper envelope of the dissipated energy, ΔW. Finally, calculate the energy dissipation factor K. dam The calculation formula is:

[0013]

[0014] Among them, K dam ΔW is the energy dissipation factor used to evaluate the magnitude and properties of shaft torsional vibration damping; n is the total number of data samples, t is time, and ΔW is the energy dissipation factor. i+1 Let ΔW be the normalized upper envelope value of the dissipation energy at the (i+1)th sampling time. i Let t(i+1) be the normalized upper envelope value of the dissipated energy at the i-th sampling time, and t(i+1) be the time value at the (i+1)-th sampling time, and t(i) be the time value at the i-th sampling time.

[0015] Step 5: Calculate the compensation angle of the damping controller using the measurement data, determine the phase shifter parameters of the additional damping controller using the residue method, and determine the energy dissipation factor K based on the measured data. dam Determine the additional damping controller gain K add The magnitude of the additional damping controller gain K add The formula is:

[0016]

[0017] Where K1 and K2 are proportionality coefficients;

[0018] Step 6: Based on the energy dissipation factor K dam The value is used to evaluate the magnitude and nature of the shaft system's torsional vibration damping. If the torsional vibration damping is poor, the damping controller is activated to suppress the shaft system's torsional vibration.

[0019] Preferably, the compensation angle of the damping controller in step 5 is calculated in the following way:

[0020] When a doubly-fed wind turbine experiences torsional vibration, the system exhibits a dominant oscillation mode σ1±jω1, and the expressions for the changes in any two electrical quantities y1 and y2 are as follows:

[0021]

[0022] Where A1 and A2 are the amplitudes of y1 and y2 under the dominant oscillation mode of the system; and The phases of y1 and y2 are defined in the system's dominant oscillation mode.

[0023]

[0024] Complex signals z1 and z2 are constructed using the Hilbert transform. The expressions for these complex signals are as follows:

[0025]

[0026] Taking the logarithm of the complex signals z1 and z2 respectively, we obtain the complex signals l1 and l2.

[0027]

[0028] The phase difference between the two electrical quantities y1 and y2 for:

[0029]

[0030] Where Im[·] represents the imaginary part, and the compensation angle of the damping controller is the phase difference between the rotor d-axis current and the electromagnetic torque, which is calculated in the above manner.

[0031] Preferably, when determining the phase shifter parameters of the additional damping controller using the residue method in step 5, the phase shift caused by the filtering stage also needs to be considered, specifically including:

[0032] The transfer function of the filtering stage is:

[0033]

[0034] Where K(s) is the transfer function of the filter, and T ω The time constant of the filter;

[0035] Leading phase generated by the filter for:

[0036]

[0037] The angle that the phase compensation stage should compensate for

[0038]

[0039] in, The phase compensation angle for the damping controller;

[0040] The formula for setting the phase shifter parameters using the residue method is:

[0041]

[0042] Where, ω i Let be the angular frequency of the shaft system torsional vibration, m be the number of phase compensation elements, and T be the angular frequency. a and T b is the time constant of the phase shifter.

[0043] Preferably, the damping controller includes a filtering stage, a phase compensation stage, and a gain stage, wherein the transfer function of the phase compensation stage is:

[0044]

[0045] Where G(s) is the transfer function of the phase shifter, T a and T b Let be the time constant of the phase shifter, and s be the Laplace operator.

[0046] Preferably, the input signal of the damping controller is the speed difference between the high-speed shaft and the low-speed shaft, and the output is connected to the current loop of the rotor-side converter to adjust the electromagnetic torque by affecting the magnitude of the rotor d-axis current.

[0047] To address the aforementioned problems, this invention also provides a torsional vibration damping assessment and suppression device for the shaft system of a grid-type doubly-fed induction generator based on dissipated energy, used to perform the aforementioned method for assessing and suppressing torsional vibration damping of the shaft system of a grid-type doubly-fed induction generator based on dissipated energy, comprising:

[0048] The acquisition module is used to acquire data of various electrical quantities during the operation of the doubly fed wind turbine, including data of each electrical quantity at the steady-state operating point and data when oscillation occurs;

[0049] The calculation module is used to preprocess the data acquired by the acquisition module and calculate the dissipated energy and energy dissipation factor K of the shaft system. dam And determine the compensation angle, phase shifter parameters and gain of the damping controller;

[0050] The judgment module is used to determine whether shaft torsional vibration has occurred based on the data acquired by the acquisition module, and to determine whether the vibration has occurred based on the energy dissipation factor K. dam The value determines whether the damping controller needs to be engaged;

[0051] An execution module is used to activate the damping controller to suppress shaft torsional vibration when the judgment module determines that the damping controller needs to be activated.

[0052] Beneficial effects

[0053] Precise and efficient torsional vibration suppression: Constructing an energy dissipation factor K based on dissipated energy dam It can quantitatively assess the magnitude and nature of shaft torsional vibration damping, and adjust the damping controller gain and parameters accordingly. It can effectively suppress torsional vibration in different scenarios such as weak damping and negative damping, significantly accelerate the speed convergence speed, and avoid torsional vibration divergence damage to the unit.

[0054] Controller adaptive adjustment: The damping controller gain is based on the energy dissipation factor K. dam Adaptive matching means that the weaker the damping is when there is positive damping and the larger the absolute value is when there is negative damping, the greater the output compensation of the controller. It can adapt to the dynamic changes of torsional vibration without manual intervention, thus improving control flexibility and response speed.

[0055] Low data dependency and easy implementation: The required data, such as speed, torque and current, are obtained through conventional measurements of the unit, without the need for additional complex sensing equipment; the core calculation is based on mature algorithms such as Hilbert transform and residue method, with clear logic and easy engineering implementation, adapting to the actual operation scenarios of grid-type doubly fed wind turbine units.

[0056] Ensuring dual safety for both the system and the unit: Effectively suppressing shaft torsional vibration avoids system stability risks caused by the coupling of torsional vibration with grid electromechanical oscillations, reduces the impact damage of torsional vibration on the unit's mechanical components, extends the unit's service life, and provides important support for the safe and stable operation of high-proportion wind power grid-connected systems.

[0057] It does not affect steady-state operating characteristics: The damping controller has a built-in filter that only functions when torsional vibration occurs. It will not interfere with the active and reactive power tracking performance of the unit during normal steady-state operation, thus balancing the torsional vibration suppression effect with the unit's normal operating requirements. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings involved in the embodiments or the prior art are briefly described below. Obviously, these drawings illustrate several embodiments of the present invention, and those skilled in the art can derive other possible drawings based on these drawings without creative effort. The purpose of the drawings is limited to illustrating specific embodiments and does not limit the scope of the present invention.

[0059] Figure 1 This is a structural diagram of the damping controller provided in an embodiment of the present invention;

[0060] Figure 2 This is a schematic diagram of the steps of the method for evaluating and suppressing the torsional vibration damping of the shaft system of a grid-type doubly fed wind turbine based on dissipated energy provided in an embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of the composition of the damping evaluation-suppression device provided in this invention example;

[0062] Figure 4 This is a schematic diagram of a grid-connected doubly-fed wind turbine system provided in an embodiment of the present invention;

[0063] Figure 5 This is a diagram illustrating the effect of a damping controller under weak damping conditions in a specific example provided in this embodiment of the invention.

[0064] Figure 6 This is a diagram illustrating the effect of the damping controller under negative damping conditions in a specific example provided by the embodiments of the present invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0066] In DFIG (Doubly-Fed Induction Generator) active response grids with grid-based control, the shaft torsional vibration problem becomes more complex. Furthermore, the frequency of the shaft torsional vibration is in the same frequency band as the electromechanical oscillation frequency of the grid, making coupling easy and posing a serious challenge to the safe operation of the power system. To address these issues, this invention provides a method for evaluating and suppressing shaft torsional vibration damping in grid-based doubly-fed induction generators based on dissipative energy. In this proposed method, the data used can be obtained through measurement, and the gain of the damping controller can be adaptively adjusted according to the shaft torsional vibration damping strength. The following is a detailed description:

[0067] The damping controller structure designed in this invention is as follows: Figure 1 As shown. Since the shaft speed is a large factor in the oscillation mode of shaft torsional vibration, the shaft speed can be used as the input to the additional damping controller. Because the inertia of the wind turbine mass is much greater than that of the generator mass, the speed change of the low-speed shaft is much smaller than that of the high-speed shaft when torsional vibration occurs, and the speed changes of the low-speed shaft and high-speed shaft are in opposite directions. Therefore, the speed difference between the high-speed and low-speed shafts is chosen as the input signal to the additional damping controller to improve observability. The output of the damping controller is connected to the current loop of the rotor-side converter. The output of the damping controller directly affects the magnitude of the rotor d-axis current, thereby regulating the electromagnetic torque. The damping controller consists of three parts: a filtering stage, a phase compensation stage, and a gain stage. The phase compensation stage is used to adjust the phase of the speed difference and the rotor d-axis current, and the gain stage is used to adjust the output of the damping controller. To avoid affecting the output characteristics in steady state, a filtering stage is also required.

[0068] The transfer function of the phase compensation stage is:

[0069]

[0070] Where G(s) is the transfer function of the phase shifter, T a and T b Let be the time constant of the phase shifter, and s be the Laplace operator.

[0071] The transfer function of the filtering stage is:

[0072]

[0073] Where K(s) is the transfer function of the filter, and T ω The time constant of the filter;

[0074] Figure 2 This is a schematic diagram of the shaft torsional vibration damping evaluation and suppression method for grid-type doubly-fed induction generators based on dissipated energy, provided in an embodiment of the present invention. Figure 2As shown, a shaft torsional vibration suppression method based on dissipated energy is implemented by a shaft torsional vibration damping assessment and suppression device based on dissipated energy. The method includes the following steps: acquiring electrical quantity data of a voltage source type DFIG, including calculating the changes of each state quantity relative to its steady-state value. The acquired electrical quantities include the mechanical torque of the wind turbine, the rotational speed of the wind turbine, the electromagnetic torque of the generator, the rotational speed of the generator, and the rotor d-axis current. The dissipated energy of the shaft system is calculated based on the acquired data.

[0075] The method for calculating the dissipated energy of a shaft system is as follows:

[0076] ΔW H =∫ΔT r dΔθ r -D sh ∫(Δω r -Δω g ) 2 dt-∫ΔT e dΔθ g

[0077] Wherein, ΔW H T represents the dissipated energy of the shaft system. r For the mechanical torque of the wind turbine; Δθ r D represents the change in the wind turbine's rotation angle relative to its steady-state value. sh Here, Δω represents the shaft system stiffness coefficient and shaft system damping coefficient. r Δω represents the change in wind turbine speed relative to its steady-state value. g T represents the change in generator speed relative to its steady-state value. e For the electromagnetic torque of the generator; Δθ g The change in generator rotation angle relative to its steady-state value; the subscript 0 indicates the steady-state value of the corresponding variable;

[0078] The dissipated energy m(t) = ΔWH obtained above is subjected to a Hilbert transform h(t) = H[m(t)], where H[m(t)] is the Hilbert transform of the signal; this forms the analytic signal of the dissipated energy x(t) = m(t) + jh(t); the magnitude A(t) = |x(t)| of the analytic signal x(t) is calculated to obtain amplitude information. A(t) is the upper envelope of the dissipated energy, representing the variation law of the oscillation amplitude of the dissipated energy and reflecting the variation trend of the original signal. Normalizing it with z-score yields the trend curve ΔW of the dissipated energy. The trend of dissipated energy reflects the rate of energy consumption. When oscillation occurs, there is energy conversion in the system, and due to damping, energy is continuously consumed during the conversion process. The faster the energy is consumed, the stronger the system damping. Therefore, the trend of dissipated energy is a measure of damping.

[0079] The energy dissipation factor is calculated using the dissipated energy variation trend obtained above. The energy dissipation factor reflects the magnitude and nature of the shaft system's torsional vibration damping. A larger energy dissipation factor indicates stronger torsional vibration damping of the shaft system, while a negative energy dissipation factor indicates that the shaft system's torsional vibration has negative damping.

[0080] The method for calculating the energy dissipation factor is as follows:

[0081]

[0082] Among them, K dam ΔW is the energy dissipation factor used to evaluate the magnitude and properties of shaft torsional vibration damping; n is the total number of data samples, t is time, and ΔW is the energy dissipation factor. i+1 Let ΔW be the normalized upper envelope value of the dissipation energy at the (i+1)th sampling time. i Let t(i+1) be the normalized upper envelope value of the dissipated energy at the i-th sampling time, and t(i+1) be the time value at the (i+1)-th sampling time, and t(i) be the time value at the i-th sampling time.

[0083] If the shaft system's torsional vibration damping is poor, the gain of the damping controller is determined using the Kdam parameter. The gain of the damping controller adapts to changes in the energy dissipation factor. When the shaft system's torsional vibration damping is weak, the damping controller can output a larger gain. The magnitude of the compensation gain can be determined based on the energy dissipation factor. When the energy dissipation factor is positive, the shaft system's torsional vibration has positive damping. The smaller the value of the energy dissipation factor, the worse the shaft system's torsional vibration damping. A smaller energy dissipation factor means that the additional damping controller should output a larger compensation amount to provide more positive damping. When the energy dissipation factor is negative, it means that the shaft system's torsional vibration damping is negative. The larger the absolute value of the energy dissipation factor, the worse the torsional vibration. A larger absolute value of the energy dissipation factor means that the damping controller should output a larger compensation amount.

[0084] The method for determining the gain of the damping controller is as follows:

[0085]

[0086] Where K1 and K2 are proportionality coefficients;

[0087] The damping controller needs to compensate for the phase difference between the rotor d-axis current and the electromagnetic torque, which can be obtained from measurement data, as detailed below. When a doubly-fed wind turbine experiences torsional vibration, a dominant oscillation mode σ1±jω1 exists in the system. The expressions for the changes in any two electrical quantities y1 and y2 are as follows:

[0088]

[0089] Where A1 and A2 are the amplitudes of y1 and y2 under the dominant oscillation mode of the system; and The phases of y1 and y2 are defined in the system's dominant oscillation mode.

[0090] Complex signals z1 and z2 are constructed using the Hilbert transform. The original signals y1 and y2 are the real parts of the complex signals z1 and z2. The expressions for z1 and z2 are:

[0091]

[0092] According to Euler's formula, complex signals z1 and z2 can be written in the following form:

[0093]

[0094] The constructed complex signal contains the amplitude and phase information of the original signal. To separate the amplitude and phase information, the logarithms of the complex signals z1 and z2 are taken respectively to obtain complex signals l1 and l2.

[0095]

[0096] Angle of the original signal y1 This refers to the imaginary part of the constructed signal l1; the angle of y2. This is the imaginary part of the constructed signal l2. Therefore, the phase difference between any two electrical quantities y1 and y2 in the dominant oscillation mode is... It is equal to the difference between the imaginary parts of their respective complex signals, and its expression is shown below:

[0097]

[0098] Where Im[·] represents the imaginary part, and the compensation angle of the damping controller is the phase difference between the rotor d-axis current and the electromagnetic torque, which is calculated in the above manner.

[0099] Therefore, the angle that the damping controller needs to compensate for can be calculated from the measured signals of the rotor d-axis current and electromagnetic torque.

[0100] When designing the phase compensation stage, the phase shift introduced by the filtering stage needs to be considered.

[0101] The expression for the leading phase generated by the filter is:

[0102]

[0103] in, The phase shift generated by the filter,

[0104] Therefore, the phase compensation stage should compensate for the angle. for:

[0105]

[0106] in, The phase compensation angle for the damping controller;

[0107] The control parameters of the phase shifter are set using the residue method.

[0108] The formula for the residue method is shown below:

[0109]

[0110] Where, ω i Let be the angular frequency of the shaft system torsional vibration, m be the number of phase compensation elements, and T be the angular frequency. a and T b is the time constant of the phase shifter.

[0111] Based on the above embodiments, Figure 3 A schematic diagram of a shaft torsional vibration damping evaluation and suppression device for a grid-type doubly-fed wind turbine based on dissipated energy, provided in an embodiment of the present invention, is shown below. Figure 3 As shown, this embodiment of the invention provides a shaft torsional vibration damping assessment and suppression device for grid-type doubly-fed wind turbines based on dissipated energy, comprising:

[0112] The module is used to acquire data of various variables required for subsequent calculations; the module is used to process and calculate the data of various variables in the system acquired by the module to obtain the energy dissipation factor of shaft torsional vibration and the parameters of the damping controller; the module is used to determine whether the damping controller needs to be activated; and the module is used to activate the damping controller.

[0113] This invention provides a shaft torsional vibration damping evaluation and suppression device for grid-type doubly fed wind turbines based on dissipated energy, used to execute the methods described in the above embodiments. The specific steps of executing the methods described in the above embodiments using the device provided in this embodiment are the same as those in the above embodiments, and will not be repeated here.

[0114] Specific examples:

[0115] Figure 4The example system shown is a grid-connected doubly-fed induction generator (DFIG) wind turbine system. The rotor-side converter uses VSG control, while the grid-side converter uses conventional vector control. An additional damping controller is integrated into the inner current loop control structure of the rotor-side converter. The wind farm outputs 600 MV of power. A three-phase short-circuit fault is applied to the infinite bus to simulate a potential accident in the actual system. Torsional vibration occurs in the shaft system of the DFIG wind turbine. Modal analysis of the system yields a torsional vibration frequency of 2.23 Hz and a torsional vibration damping ratio of 4.23%. Calculation of the energy dissipation factor reveals poor shaft torsional vibration damping. The gain coefficient of the damping controller is calculated using the energy dissipation factor, and the parameters of the phase shifter are calculated using the residue method and immediately activated by the damping controller, suppressing the shaft torsional vibration. Tables 1 and 2 show the damping controller parameters obtained using the method proposed in this invention under weak and negative damping conditions, respectively.

[0116] Table 1 Controller parameter settings under weak damping condition

[0117]

[0118] Table 2 Controller parameter settings under negative damping conditions

[0119]

[0120] Figure 5 and Figure 6 The effects of the damping controller under weak and negative damping conditions are presented. As can be seen from the figures, when the shaft torsional vibration has positive damping, the high-speed shaft speed exhibits a convergent trend. After the additional damping controller is applied, the convergence speed significantly accelerates and eventually stabilizes. When the shaft torsional vibration has negative damping, the high-speed shaft speed exhibits a divergent trend. After the additional damping controller is applied, the divergence is suppressed and the speed quickly stabilizes. This demonstrates that the proposed method can effectively suppress shaft torsional vibration in a voltage-source DFIG.

[0121] Those skilled in the art should understand that the above embodiments are merely illustrative of the content of this disclosure and do not limit its scope. The system capacity, voltage, line parameters, etc., shown may vary depending on the specific circumstances of the power electronic grid-connected generator set and its grid connection. Based on this disclosure, those skilled in the art can make other changes or adjustments, and these changes still fall within the scope of this disclosure.

Claims

1. A method for evaluating and suppressing torsional vibration damping of the shaft system in a grid-type doubly-fed wind turbine based on dissipated energy, characterized in that, Includes the following steps: Step 1: Obtain data of various electrical quantities during the operation of the doubly-fed wind turbine. The electrical quantities include data of each electrical quantity at the steady-state operating point and data when oscillation occurs. Based on the data of various electrical quantities during the operation of the doubly-fed wind turbine, determine whether shaft torsional vibration has occurred. Step 2: When torsional vibration occurs, the electrical quantity data of each generator in the system are preprocessed to obtain the change of each electrical quantity relative to the steady-state value. Step 3: Calculate the dissipated energy ΔW of the shaft system using the changes of each electrical quantity relative to its steady-state value. H The calculation formula is: ΔW H =∫ΔT r dΔθ r -D sh ∫(See r -See g ) 2 dt-∫ΔT e dΔθ g Wherein, ΔW H T represents the dissipated energy of the shaft system. r For the mechanical torque of the wind turbine; Δθ r D represents the change in the wind turbine's rotation angle relative to its steady-state value. sh Here, Δω represents the shaft system stiffness coefficient and shaft system damping coefficient. r Δω represents the change in wind turbine speed relative to its steady-state value. g T represents the change in generator speed relative to its steady-state value. e For the electromagnetic torque of the generator; Δθ g The change in generator angle relative to its steady-state value; Step 4: The dissipated energy ΔW H Perform a Hilbert transform to obtain the upper envelope of the dissipated energy. Then, perform Z-score normalization on the upper envelope to obtain the normalized upper envelope of the dissipated energy, ΔW. Finally, calculate the energy dissipation factor K. dam The calculation formula is: Among them, K dam ΔW is the energy dissipation factor used to evaluate the magnitude and properties of shaft torsional vibration damping; n is the total number of data samples, t is time, and ΔW is the energy dissipation factor. i+1 Let ΔW be the normalized upper envelope value of the dissipation energy at the (i+1)th sampling time. i Let t(i+1) be the normalized upper envelope value of the dissipated energy at the i-th sampling time, and t(i+1) be the time value at the (i+1)-th sampling time, and t(i) be the time value at the i-th sampling time. Step 5: Calculate the compensation angle of the damping controller using the measurement data, determine the phase shifter parameters of the additional damping controller using the residue method, and determine the energy dissipation factor K based on the measured data. dam Determine the additional damping controller gain K add The magnitude of the additional damping controller gain K add The formula is: Where K1 and K2 are proportionality coefficients; Step 6: Based on the energy dissipation factor K dam The value is used to evaluate the magnitude and nature of the shaft system's torsional vibration damping. If the torsional vibration damping is poor, the damping controller is activated to suppress the shaft system's torsional vibration.

2. The method for evaluating and suppressing torsional vibration damping of a doubly-fed induction generator shaft system based on dissipated energy, as described in claim 1, is characterized in that... The compensation angle of the damping controller mentioned in step 5 is calculated in the following way: When a doubly-fed wind turbine experiences torsional vibration, the system exhibits a dominant oscillation mode σ1±jω1, and the expressions for the changes in any two electrical quantities y1 and y2 are as follows: Where A1 and A2 are the amplitudes of y1 and y2 under the dominant oscillation mode of the system; and The phases of y1 and y2 are defined in the system's dominant oscillation mode. Complex signals z1 and z2 are constructed using the Hilbert transform. The expressions for these complex signals are as follows: Taking the logarithm of the complex signals z1 and z2 respectively, we obtain the complex signals l1 and l2. The phase difference between the two electrical quantities y1 and y2 for: Where Im[·] represents the imaginary part, and the compensation angle of the damping controller is the phase difference between the rotor d-axis current and the electromagnetic torque, which is calculated in the above manner.

3. The method for evaluating and suppressing torsional vibration damping of a doubly-fed induction generator shaft system based on dissipated energy, as described in claim 2, is characterized in that... When determining the phase shifter parameters of the additional damping controller using the residue method in step 5, the phase shift caused by the filtering stage must also be considered, specifically including: The transfer function of the filtering stage is: Where K(s) is the transfer function of the filter, and T ω The time constant of the filter; Leading phase generated by the filter for: The angle that the phase compensation stage should compensate for in, The phase compensation angle for the damping controller; The formula for setting the phase shifter parameters using the residue method is: Where, ω i Let be the angular frequency of the shaft system torsional vibration, m be the number of phase compensation elements, and T be the angular frequency. a and T b is the time constant of the phase shifter.

4. The method for evaluating and suppressing torsional vibration damping of a doubly-fed induction generator shaft system based on dissipated energy, as described in claim 1, is characterized in that... The damping controller includes a filtering stage, a phase compensation stage, and a gain stage. The transfer function of the phase compensation stage is: Where G(s) is the transfer function of the phase shifter, T a and T b Let be the time constant of the phase shifter, and s be the Laplace operator.

5. The method for evaluating and suppressing torsional vibration damping of a doubly-fed induction generator shaft system based on dissipated energy, as described in claim 1, is characterized in that... The input signal of the damping controller is the speed difference between the high-speed shaft and the low-speed shaft, and the output is connected to the current loop of the rotor-side converter. The electromagnetic torque is adjusted by affecting the magnitude of the rotor d-axis current.

6. A device for evaluating and suppressing torsional vibration damping of a doubly-fed induction generator shaft system based on dissipated energy, characterized in that, The method for evaluating and suppressing shaft torsional vibration damping of a grid-type doubly-fed wind turbine based on dissipated energy as described in any one of claims 1-5 includes: The acquisition module is used to acquire data of various electrical quantities during the operation of the doubly fed wind turbine, including data of each electrical quantity at the steady-state operating point and data when oscillation occurs; The calculation module is used to preprocess the data acquired by the acquisition module and calculate the dissipated energy and energy dissipation factor K of the shaft system. dam The acquisition module determines the compensation angle, phase shifter parameters, and gain of the damping controller; the judgment module determines whether shaft torsional vibration has occurred based on the data acquired by the acquisition module, and determines the energy dissipation factor K. dam The value determines whether the damping controller needs to be engaged; An execution module is used to activate the damping controller to suppress shaft torsional vibration when the judgment module determines that the damping controller needs to be activated.

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