Improved optimal tracking rotor control method for wind turbine MPPT

Abstract

The application discloses an improved optimal tracking rotor control method for MPPT of a wind turbine, and comprises the following contents: based on the basic principle of a traditional OTR method, a wind turbine controller introduces a compensation loop of the difference between aerodynamic torque and optimal torque in an electromagnetic torque instruction, and dynamically adjusts a compensation coefficient in the compensation loop according to a current wind speed measurement value and a wind wheel acceleration signal, so as to adjust the torque error compensation amount under different wind speeds, thereby mainly enhancing the MPPT performance of the wind turbine in a high wind speed area. Compared with the traditional OTR method adopting a constant compensation coefficient, the method can obtain more wind energy capture amount with a smaller load cost.

Description

Technical Field

[0001] This invention belongs to the field of MPPT control technology for wind turbines, and in particular, it is an improved optimal tracking rotor (OTR) control method for MPPT of wind turbines. Background Technology

[0002] MPPT (Maximum Power Point) is the primary operating mode for wind turbines operating below rated wind speed, making its efficiency crucial. The most common MPPT method is the Optimal Torque (OT) method. This method controls the output electromagnetic torque based on the optimal torque curve, using the imbalance between aerodynamic and electromagnetic torque to accelerate and decelerate the rotor, gradually converging to the maximum power point. This strategy is simple and produces relatively stable electromagnetic torque, making it the most widely used MPPT method in industrialized large-scale wind turbines.

[0003] In actual wind turbine operation under turbulent wind speeds, the turbine is mostly in the tracking process rather than at its steady-state operating point. This results in poor wind energy capture performance for the OT method, which is based on the steady-state optimal torque curve, necessitating improvement from a tracking dynamics perspective. By adding an extra torque to the electromagnetic torque command of the OT method, the imbalance torque between aerodynamic and electromagnetic torque can be further increased, thereby improving tracking dynamic performance. Representative methods include constant bandwidth control, inertia compensation control, and Optimally Tracking Rotor (OTR) control. In the OTR method, the additional torque is introduced into the electromagnetic torque command as a compensation for the difference between the aerodynamic torque and the optimal torque, and the magnitude of the additional torque is adjusted by changing the compensation coefficient. While the OTR method can increase the torque compensation and thus improve wind energy capture efficiency by setting a larger compensation coefficient, this also causes stronger electromagnetic torque fluctuations and increases the load on the wind turbine drivetrain.

[0004] It is important to note that high-wind-speed areas contain significantly more energy than low-wind-speed areas. This means there is a difference in tracking value between the two. With the same reduction in tracking error, the incremental wind energy capture gained from tracking high-wind-speed areas is significantly greater than that from tracking low-wind-speed areas, while the load costs are roughly the same. However, traditional OTR methods use a constant compensation coefficient for any wind speed, ignoring the difference in tracking value between high and low wind speeds. This results in a considerable portion of the load being generated in low-wind-speed areas with lower tracking value, leading to excessive rotational speeds in the low-speed range, reducing the proportion of tracking high-wind-speed areas, and resulting in a significant load cost without achieving the desired improvement in wind energy capture efficiency. Current research on OTR methods has not yet considered dynamically adjusting the compensation coefficient based on the tracking value of wind speed. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art. Considering that MPPT control technology is an important technical means for wind turbines, and addressing the problem that the traditional OTR method ignores the value of wind speed tracking and focuses too much on low wind speed areas, this invention proposes an improved OTR control method for wind turbines. This method dynamically adjusts the compensation coefficient based on the current wind speed conditions and the magnitude of the rotor acceleration, focusing on enhancing the rotor tracking performance in high wind speed areas, and achieving an overall optimized control performance effect of high efficiency under low load.

[0006] The technical solution to achieve the purpose of this invention is: an improved optimal tracking rotor control method for wind turbine MPPT, wherein the wind turbine controller outputs an electromagnetic torque command value in MPPT operation mode as follows:

[0007] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0008] In the formula, T e For electromagnetic torque command; T m The aerodynamic torque is calculated as follows: T m =0.5ρπR 5 C p (λ)ω 2 / λ 3 Where ρ is the air density, R is the rotor radius, ω is the rotor speed, and C p (λ) is the wind energy utilization coefficient, which, when the blade pitch angle is set to 0°, is only related to the tip speed ratio λ = ωR / v, where v is the current wind speed; K opt ω 2 For optimal torque, The optimal tip speed ratio λ opt The corresponding maximum wind energy utilization coefficient; G is the compensation coefficient, which is dynamically adjusted based on the current wind speed and wind turbine acceleration signal.

[0009] Furthermore, the compensation coefficient G is dynamically adjusted based on the current wind speed and wind turbine acceleration signals. The specific process includes:

[0010] Step 2-1: The anemometer samples the current instantaneous wind speed and sends the instantaneous wind speed measurement value to the wind turbine controller; at the same time, the wind turbine controller acquires the wind turbine acceleration signal at this time.

[0011] Step 2-2: The wind turbine controller dynamically adjusts the compensation coefficient G based on the measured wind speed and the rotor acceleration. The adjustment formula is as follows:

[0012]

[0013] In the formula, g1 represents the wind turbine acceleration; g2 and g1 are weighting coefficients obtained in advance through wind turbine modeling and simulation, applicable to different wind turbine models.

[0014] Furthermore, the weighting coefficients g1 and g2 are specifically obtained as follows:

[0015] Step 3-1: Based on the structural and control parameters of the wind turbine, a simplified mathematical model of the wind turbine is pre-constructed:

[0016]

[0017]

[0018] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0019] Step 3-2: According to the requirements of IEC61400-1 standard, generate various typical wind conditions: change the average wind speed (4-7 m / s, with a change step of 1 m / s), turbulence intensity level (A, B, C) and integral scale (100-500 m, with a change step of 50 m) in sequence to generate n turbulent wind speed sequences for each wind condition with a duration of t1 min and a wind speed sampling period of t2 s;

[0020] Step 3-3, according to the rated torque limit T eN Determine the allowable range of values ​​for g1 and g2: Set the initial values ​​of g1 and g2 to 0, change the values ​​of g1 and g2 in turn, perform time-domain simulation for each turbulent wind speed sequence in step 3-2 based on the simplified mathematical model of the wind turbine, and record the load until the output electromagnetic torque exceeds the set threshold, then stop the search.

[0021] Steps 3-4: Based on the simplified mathematical model of the wind turbine, for each turbulent wind speed sequence described in Step 3-2, time-domain simulation is performed using the traditional OTR method, and the load is recorded.

[0022] Steps 3-5: Calculate the average load reduction rate of each group g1 and g2 compared to the load corresponding to the traditional OTR method;

[0023] Steps 3-6: Among groups g1 and g2, select the weighting coefficient with the highest average load reduction rate.

[0024] Compared with the prior art, the significant advantages of this invention are:

[0025] 1) The compensation coefficient is dynamically adjusted according to wind speed and wind turbine acceleration, so that the wind turbine MPPT pays more attention to high wind speed areas with more energy and greater tracking value, thus achieving the control performance optimization effect of obtaining more wind energy capture at the cost of less load.

[0026] 2) The above dynamic adjustment method also takes into account the wind turbine's operating status. During the acceleration phase, G is increased to allow the wind turbine to enter the high wind speed area more quickly; during the deceleration phase, G is decreased to prevent the speed from excessively entering the low speed range and affecting the subsequent tracking effect.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 The control block diagram for improving the MPPT optimal tracking rotor control method of wind turbine units.

[0029] Figure 2 Figure (a) shows the speed tracking trajectory diagram and compensation coefficients of the OT method, the traditional OTR method, and the improved wind turbine MPPT optimal tracking rotor control method in the embodiments of the present invention, and Figure (b) shows the compensation coefficient diagram. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] In one embodiment, an improved optimal tracking rotor control method for wind turbine MPPT is provided. Based on the basic principle of the traditional OTR method, the wind turbine controller introduces a compensation loop for the difference between aerodynamic torque and optimal torque in the electromagnetic torque command. The compensation coefficient in the compensation loop is dynamically adjusted according to the current wind speed measurement value and the wind turbine acceleration signal, so as to adjust the torque error compensation amount under different wind speeds, thereby focusing on enhancing the MPPT performance of the wind turbine in high wind speed areas.

[0032] The control block diagram for the MPPT operation mode is as follows: Figure 1 As shown, the structure and control parameters of the wind turbine generator set and C P The (λ,β) curves are shown in Table 1 below:

[0033] Table 1. Structure and Control Parameters of Wind Turbine Units

[0034]

[0035]

[0036] λ i = [1 / (λ+0.08β)-0.035 / (1+β)] 3 )] -1

[0037] In the formula, when the pitch angle β is 0°, the wind energy utilization coefficient C p (λ) depends only on the tip speed ratio λ=ωR / v The optimal tip speed ratio λ opt The corresponding maximum wind energy utilization coefficient.

[0038] In this embodiment, the electromagnetic torque command value output by the wind turbine controller in MPPT operation mode is:

[0039] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0040] In the formula, T e For electromagnetic torque command; T m The aerodynamic torque is calculated as follows: T m =0.5ρπR 5 C p (λ)ω 2 / λ 3 Where ρ is the air density, R is the rotor radius, ω is the rotor speed, and v is the current wind speed; K opt ω 2 For optimal torque, G is the compensation coefficient, which is dynamically adjusted based on the current wind speed and wind turbine acceleration signal.

[0041] In this embodiment, the compensation coefficient G is dynamically adjusted based on the current wind speed and wind turbine acceleration signal, including the following steps:

[0042] Step 1: The anemometer samples the current instantaneous wind speed and sends the instantaneous wind speed measurement value to the wind turbine controller; at the same time, the wind turbine controller acquires the wind turbine acceleration signal at this time.

[0043] Step 2: The wind turbine controller dynamically adjusts the compensation coefficient G according to the measured wind speed and the rotor acceleration, based on the following mathematical expression:

[0044]

[0045] In the formula, g1 represents the wind turbine acceleration; g2 and g1 are weighting coefficients obtained in advance through wind turbine modeling and simulation, applicable to the wind turbine model.

[0046] Here, the advantage of dynamically adjusting the compensation coefficient G based on the current wind speed and rotor acceleration signal is that, since the energy contained in high and low wind speeds differs, i.e., their tracking value differs, this dynamic adjustment method is based on distinguishing wind speed conditions. In high wind speed areas, G is increased to enhance rotor tracking performance, while in low wind speed areas, G is decreased to avoid unnecessary load growth, thus achieving an overall optimized control performance effect of low load and high efficiency. Furthermore, this dynamic adjustment method also considers the rotor's operating state, increasing G during the acceleration phase to allow the wind turbine to enter the high wind speed area more quickly; and decreasing G during the deceleration phase to prevent the rotational speed from excessively entering the low-speed range and affecting subsequent tracking performance.

[0047] In this embodiment, g1 and g2 are weighting coefficients applicable to the wind turbine model, obtained in advance through wind turbine modeling and simulation, including:

[0048] Step 1: Based on the structural and control parameters of the wind turbine generator set as described in Table 1, a simplified mathematical model of the wind turbine generator set is pre-constructed:

[0049]

[0050]

[0051] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0052] Step 2: According to the requirements of IEC61400-1 standard, generate various typical wind conditions: change the average wind speed (4-7 m / s, with a change step of 1 m / s), turbulence intensity level (A, B, C) and integral scale (100-500 m, with a change step of 50 m) in sequence to generate 5 turbulent wind speed sequences for each wind condition, with a duration of 10 min and a wind speed sampling period of 0.05 s.

[0053] Step 3, according to the rated torque limit T eN Determine the allowable value ranges of g1 and g2: Set the initial values ​​of g1 and g2 to 0, and change the values ​​of g1 and g2 sequentially (with change steps of 0.01 and 1 respectively). Based on the simplified wind turbine model, perform time-domain simulation for each turbulent wind speed sequence described in step 2 and record the load until the output electromagnetic torque exceeds 110%T. eN Stop searching;

[0054] Step 4: Based on the simplified model of the wind turbine, perform time-domain simulation and record the load for each turbulent wind speed sequence described in Step 2 using the traditional OTR method. The constant compensation coefficient of the traditional OTR method is set to 2.

[0055] Step 5: Calculate the average load reduction rate of each group g1 and g2 compared to the load corresponding to the traditional OTR method;

[0056] Step 6: Select the weighting coefficient setting value with the highest average load reduction rate from each group g1 and g2. g1 and g2 are 0.12 and 40, respectively.

[0057] In one embodiment, an improved optimal tracking rotor control system for wind turbine MPPT is provided, in which the wind turbine controller outputs an electromagnetic torque command value in MPPT operation mode as follows:

[0058] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0059] In the formula, T e For electromagnetic torque command; T m The aerodynamic torque is calculated as follows: T m =0.5ρπR 5 C p (λ)ω 2 / λ 3 Where ρ is the air density, R is the rotor radius, ω is the rotor speed, and C p (λ) is the wind energy utilization coefficient, which, when the blade pitch angle is set to 0°, is only related to the tip speed ratio λ = ωR / v, where v is the current wind speed; K opt ω 2 For optimal torque, The optimal tip speed ratio λ opt The corresponding maximum wind energy utilization coefficient; G is the compensation coefficient, which is dynamically adjusted based on the current wind speed and wind turbine acceleration signal.

[0060] Specific limitations regarding the improved optimal tracking rotor control system for wind turbine MPPT can be found in the limitations of the improved optimal tracking rotor control method for wind turbine MPPT mentioned above, and will not be repeated here. Each module in the improved optimal tracking rotor control system for wind turbine MPPT described above can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0061] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to perform the following:

[0062] The wind turbine controller outputs the electromagnetic torque command value under MPPT operation mode as follows:

[0063] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0064] In the formula, T e For electromagnetic torque command; T m The aerodynamic torque is calculated as follows: T m =0.5ρπR 5 C p (λ)ω 2 / λ 3 Where ρ is the air density, R is the rotor radius, ω is the rotor speed, and C p (λ) is the wind energy utilization coefficient, which, when the blade pitch angle is set to 0°, is only related to the tip speed ratio λ = ωR / v, where v is the current wind speed; K opt ω 2 For optimal torque, The optimal tip speed ratio λ opt The corresponding maximum wind energy utilization coefficient; G is the compensation coefficient, which is dynamically adjusted based on the current wind speed and wind turbine acceleration signal.

[0065] For specific limitations, please refer to the limitations of the improved optimal tracking rotor control method for wind turbine MPPT mentioned above, which will not be repeated here.

[0066] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, performs the following:

[0067] The wind turbine controller outputs the electromagnetic torque command value under MPPT operation mode as follows:

[0068] T e =K opt ω 2 -G(T m -K opt ω 2 )

[0069] In the formula, T e For electromagnetic torque command; T m The aerodynamic torque is calculated as follows: T m =0.5ρπR 5 C p (λ)ω 2 / λ 3 Where ρ is the air density, R is the rotor radius, ω is the rotor speed, and C p (λ) is the wind energy utilization coefficient, which, when the blade pitch angle is set to 0°, is only related to the tip speed ratio λ = ωR / v, where v is the current wind speed; K opt ω 2 For optimal torque, The optimal tip speed ratio λ opt The corresponding maximum wind energy utilization coefficient; G is the compensation coefficient, which is dynamically adjusted based on the current wind speed and wind turbine acceleration signal.

[0070] For specific limitations, please refer to the limitations of the improved optimal tracking rotor control method for wind turbine MPPT mentioned above, which will not be repeated here.

[0071] As a specific example, the invention will be further described in detail in one embodiment. According to the IEC 61400-1 standard, a turbulent wind speed sequence with a duration of 10 minutes and a wind speed sampling period of 0.05 seconds was randomly generated. MPPT control was then implemented on the wind turbine based on the OT method, the method proposed in this invention, and the traditional OTR method using a constant compensation coefficient. The constant compensation coefficient should be chosen such that the average wind energy capture efficiency P obtained by the traditional OTR method is... favg P, in relation to the method proposed in this invention favg Equal, thus facilitating comparison of loads under the premise of equal average wind energy capture efficiency.

[0072] Furthermore, the wind turbine speed tracking trajectories and corresponding compensation coefficients under the three methods are as follows: Figure 2 The figure shows the average wind energy capture efficiency, load, and the percentage increase in load. As shown in Table 2.

[0073] Table 2 Simulation data results for the three MPPT methods

[0074]

[0075] Depend on Figure 2 It can be seen that the method proposed in this invention maintains the G-value at a high level in the high-wind-speed region, accelerates the dynamic process of rotational speed tracking in this region, and avoids over-tracking of low-wind-speed targets to a certain extent. Therefore, according to the data results, the load growth rate of the method proposed in this invention is only 43.33%, which saves 31.48% compared with the traditional OTR method, achieving an equal average wind energy capture efficiency at a lower load cost.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An improved optimal tracking rotor control method for MPPT in wind turbine generators, characterized in that, The wind turbine controller outputs the electromagnetic torque command value under MPPT operation mode as follows: ； In the formula, This is an electromagnetic torque command; The aerodynamic torque is calculated as follows: ,in air density, Where is the radius of the wind turbine. The wind turbine rotation speed, The wind energy utilization coefficient, when the blade pitch angle is set to 0°, is only related to the tip speed ratio. related, This is the current wind speed value; For optimal torque, , For the optimal tip speed ratio The corresponding maximum wind energy utilization coefficient; The compensation coefficient is dynamically adjusted based on the current wind speed and wind turbine acceleration signals. The compensation coefficient is adjusted based on the current wind speed and wind turbine acceleration signals. Dynamic adjustments are made, and the specific process includes: Step 2-1: The anemometer samples the current instantaneous wind speed and sends the instantaneous wind speed measurement value to the wind turbine controller; at the same time, the wind turbine controller acquires the wind turbine acceleration signal at this time. Step 2-2: The wind turbine controller adjusts the compensation coefficient based on the measured wind speed and rotor acceleration. Dynamic adjustments are made, and the adjustment formula is as follows: ； In the formula, For wind turbine acceleration; These are weighting coefficients applicable to wind turbine models, obtained in advance through wind turbine modeling and simulation.

2. The improved optimal tracking rotor control method for wind turbine MPPT according to claim 1, characterized in that, The weighting coefficients The specific method of obtaining it is as follows: Step 3-1: Based on the structural and control parameters of the wind turbine, a simplified mathematical model of the wind turbine is pre-constructed: ； ； ； Step 3-2: According to the requirements of IEC61400-1 standard, generate various typical wind conditions: change the average wind speed, turbulence intensity level and integral scale in turn to generate n turbulence wind speed sequences for each wind condition with a duration of t1min and a wind speed sampling period of t2s. Step 3-3, according to the rated torque limit Sure Allowed value range: Setting The initial values ​​are all 0, and then changed sequentially. The value of is determined by performing time-domain simulation and recording the load for each turbulent wind speed sequence in step 3-2 based on the simplified mathematical model of the wind turbine, until the output electromagnetic torque exceeds the set threshold and the search stops. Steps 3-4: Based on the simplified mathematical model of the wind turbine, for each turbulent wind speed sequence described in Step 3-2, time-domain simulation is performed using the traditional OTR method, and the load is recorded. Steps 3-5: Calculate for each group The corresponding load is compared to the average load reduction rate of the load using the traditional OTR method; Steps 3-6, in each group Among them, the weighting coefficients with the highest average load reduction rate are selected.

3. The improved optimal tracking rotor control method for wind turbine MPPT according to claim 2, characterized in that, In step 3-2, t1 = 10 min and t2 = 0.05 s.

4. The improved optimal tracking rotor control method for wind turbine MPPT according to claim 2, characterized in that, The changes described in step 3-3 The values ​​of are 0.01 and 1, respectively.

5. The improved optimal tracking rotor control method for wind turbine MPPT according to claim 2, characterized in that, In step 3-3, the threshold is set to .

6. The improved optimal tracking rotor control method for wind turbine MPPT according to claim 2, characterized in that, In steps 3-4, the constant compensation coefficient of the traditional OTR method is set to 2.

7. An improved optimal tracking rotor control system for wind turbine MPPT based on the method of any one of claims 1 to 6, characterized in that, In this system, the electromagnetic torque command value output by the wind turbine controller in MPPT operation mode is: ； In the formula, This is an electromagnetic torque command; The aerodynamic torque is calculated as follows: ,in air density, Where is the radius of the wind turbine. The wind turbine rotation speed, The wind energy utilization coefficient, when the blade pitch angle is set to 0°, is only related to the tip speed ratio. related, This is the current wind speed value; For optimal torque, , For the optimal tip speed ratio The corresponding maximum wind energy utilization coefficient; The compensation coefficient is dynamically adjusted based on the current wind speed and wind turbine acceleration signals.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the content of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the content of the method according to any one of claims 1 to 6.

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