Wind turbine tip speed ratio control with reference speed correction and simulation method

Abstract

The application relates to a wind turbine tip speed ratio control and simulation method with reference rotating speed correction, which comprises the following steps: obtaining a generator theoretical optimal rotating speed reference value based on real-time wind speed of a wind turbine and optimal tip speed ratio; inputting the generator theoretical optimal rotating speed reference value into a low-pass filter, obtaining a generator actual rotating speed reference value after filtering and limiting, constructing a rotating speed closed-loop control based on the generator actual rotating speed reference value and an actual rotating speed of the generator, calculating a generator torque reference value, and applying generator torque control based on the generator torque reference value. Compared with the prior art, the application can find a good balance among the three control targets of wind energy capture efficiency, active power fluctuation of a grid-connected unit and shaft torsional vibration load of the unit, and can adapt to performance degradation of the unit and changes of environmental air density without losing power generation when the conditions occur.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind turbine control, in particular to a wind turbine tip speed ratio control method with reference speed correction. BACKGROUND

[0002] The horizontal axis lift type wind turbine has a unique optimal tip speed ratio, when the wind turbine tip line speed and the wind speed maintain the fixed ratio of the optimal tip speed ratio, the wind energy capture efficiency is the highest.

[0003] The wind turbine maximum power tracking technology includes optimal tip speed ratio control, optimal torque control (including speed-torque lookup table control) and power signal feedback control, and the hill climbing search method. The hill climbing search method needs to continuously apply disturbance, and is more suitable for small capacity wind turbines. The optimal torque control and the power signal feedback control achieve a good balance in wind energy capture efficiency, wind turbine grid-connected active power fluctuation and wind turbine shaft mechanical load, and have better comprehensive performance, and are widely used by megawatt wind turbines, but both the maximum power tracking control technologies need to use the optimal torque coefficient. The optimal torque coefficient is theoretically a constant determined by the wind turbine characteristics, but in fact, the optimal torque coefficient will change with the change of the environmental air density or the aerodynamic performance degradation caused by the aging of the wind turbine, which will cause the wind turbine static working point to deviate in the steady state characteristics of the wind turbine power tracking, and will also have adverse effects on the dynamic characteristics of the wind turbine power tracking. Therefore, the optimal torque control and the power signal feedback control cannot well adapt to the performance degradation of the wind turbine and the change of the environmental air density, and wind energy capture efficiency will be lost when these situations occur.

[0004] The optimal tip speed ratio control is based on the basic principle of the maximum power tracking control of the horizontal axis lift type wind turbine, which has adaptability to the performance degradation of the wind turbine and the change of the environmental air density in principle. The conventional optimal tip speed ratio control detects the real-time wind speed near the wind turbine plane , calculates the optimal speed of the wind turbine according to the optimal tip speed ratio, and directly uses the optimal speed as the reference value of the wind turbine speed, constructs a speed closed loop with the measured speed value, and outputs the generator torque reference value. However, no matter how the parameters of the speed closed loop PI regulator are adjusted, huge torque fluctuation, shaft load and power fluctuation will be produced on the large wind turbine. Although the wind energy capture efficiency is slightly higher than that of the optimal torque control and the power signal feedback control, the conventional optimal tip speed ratio control has huge wind turbine grid-connected active power fluctuation and huge wind turbine shaft mechanical load when applied to the megawatt wind turbine, and therefore cannot be practically applied.

[0005] Most of the existing schemes are conventional optimum tip speed ratio control, which directly obtains the speed reference value according to the wind speed, and obtains the generator torque instruction by adopting the speed closed loop. The conventional optimum tip speed ratio control is acceptable when applied to small power wind turbine, but when applied to megawatt-level unit, the active power fluctuation amplitude of the unit grid connection is huge, the mechanical load of the unit shaft system is huge, and thus the conventional optimum tip speed ratio control cannot be practically applied. SUMMARY

[0006] The present application aims to overcome the defects of the prior art, and provides a wind turbine tip speed ratio control and simulation method with reference speed correction for high-power wind turbines to improve wind energy capture efficiency.

[0007] The object of the present application can be achieved by the following technical solutions:

[0008] The present application provides a wind turbine tip speed ratio control and simulation method with reference speed correction, comprising the following steps:

[0009] Based on the real-time wind speed of the wind turbine and the optimum tip speed ratio, the theoretical optimal speed reference value of the generator is obtained, the theoretical optimal speed reference value of the generator is input into a low-pass filter, and the actual speed reference value of the generator is obtained after filtering and limiting, so as to realize dynamic correction of the reference speed;

[0010] Based on the actual speed reference value of the generator and the actual speed of the generator, a speed closed loop control is constructed and the generator torque reference value is calculated, the generator torque control is applied based on the generator torque reference value, and the tip speed ratio control is realized through speed control and torque control.

[0011] As a preferred technical solution, the acquisition of the real-time wind speed comprises the following steps:

[0012] The wind speed information from the wind measuring device is obtained, and the real-time wind speed is obtained by a delay algorithm.

[0013] As a preferred technical solution, the delay algorithm is realized by the following formula:

[0014]

[0015] Wherein, is the real-time wind speed, is the wind speed measured by the wind measuring device, is the time required for the wind speed measured by the wind measuring device to be transmitted to the wind wheel plane, represents the complex frequency.

[0016] As a preferred technical solution, the limiting specifically is:

[0017] The upper limit of the limit is set at the generator's rated speed, and the lower limit is set at the generator's grid-connected speed.

[0018] As a preferred technical solution, the acquisition of the theoretical optimal speed reference value of the generator includes the following steps:

[0019] Based on the real-time wind speed and the optimal tip speed ratio of the wind turbine, obtain the ideal reference value for the optimal wind turbine speed.

[0020] Based on the optimal speed reference value of the wind turbine and the gear ratio of the transmission system gearbox, the theoretical optimal speed reference value of the generator is obtained.

[0021] As a preferred technical solution, generator torque control is achieved based on the wind turbine converter.

[0022] As a preferred technical solution, the expression for the low-pass filter is:

[0023]

[0024]

[0025]

[0026] in, The per-unit equivalent moment of inertia of the wind turbine. It is the per-unit value of the generator speed in a wind turbine unit. It is a coefficient determined by the parameters of the wind turbine. air density, The radius of the wind turbine blade. C pmax This represents the maximum wind energy utilization coefficient of the wind turbine. λ opt The optimal tip speed ratio.

[0027] As a preferred technical solution, the equivalent moment of inertia is obtained using the following formula:

[0028]

[0029]

[0030]

[0031] in, The per-unit equivalent moment of inertia of the wind turbine. This refers to the rated speed of the wind turbine. This is the reference value for the generator's speed. This refers to the gear ratio of the gearbox in the transmission system. The rated power of the wind turbine unit. a nominal value of the moment of inertia of the wind turbine, a nominal value of the moment of inertia of the generator.

[0032] As a preferred technical solution, the speed unit value of the generator in the wind turbine is obtained by using the following formula:

[0033]

[0034] wherein, a speed unit value of the generator in the wind turbine, an actual speed of the generator, a reference value of the speed of the generator.

[0035] As a preferred technical solution, the low-pass filter is a first-order low-pass filter with variable time constant, and the calculation process of the output of the filter comprises:

[0036] calculating the difference between the input and the feedback of the low-pass filter, inputting the difference into the integrator, and obtaining the output of the filter.

[0037] Compared with the prior art, the present application has the following advantages:

[0038] (1) For high-power wind turbines, the method reduces the active power fluctuation amplitude and the mechanical load of the shaft system: Unlike the conventional optimal tip speed ratio control, when applied to large-capacity wind turbines, the method has the problems of large grid-connected active power fluctuation and large mechanical torsional vibration load of the shaft system. The method first obtains the theoretical optimal speed reference value of the generator based on the real-time wind speed of the wind turbine and the optimal tip speed ratio, then inputs the theoretical optimal speed reference value of the generator into the low-pass filter, obtains the actual speed reference value of the generator after filtering and limiting, and finally realizes closed-loop control of the generator speed based on the actual speed reference value of the generator. The method reduces the influence of the static working point deviation of the wind turbine by setting the low-pass filter to obtain the actual speed reference value. By adding a low-pass filter after the speed reference value and designing the parameters of the low-pass filter according to the formula, the improved optimal tip speed ratio control, optimal torque control and power signal feedback control have quite good power fluctuation characteristics and shaft torsional vibration characteristics, so as to find a balance between wind energy capture efficiency, grid-connected active power fluctuation of the wind turbine and mechanical torsional vibration load of the shaft system.

[0039] (2) Reduce the impact of unit performance degradation and air density changes on the operating point: This method is an improved control strategy of optimal tip speed ratio control at its core. It inherits the basic characteristic of horizontal axis wind turbines that the wind energy utilization coefficient is the highest under the optimal tip speed ratio. It can obtain the optimal tip speed ratio and the optimal operating speed under steady state, thereby capturing the most aerodynamic power from natural wind speed. It can automatically adapt to unit performance degradation and environmental changes, such as increased mechanical loss of unit transmission system and changes in ambient air density, so as not to lose power generation when these situations occur. Attached Figure Description

[0040] Figure 1 This is a schematic block diagram of the control and simulation method for the tip speed ratio control of a wind turbine with reference speed correction in the embodiment.

[0041] Figure 2 This is a schematic block diagram illustrating the application control of the wind turbine tip speed ratio control and simulation method with reference speed correction in the embodiment.

[0042] Figure 3 A block diagram illustrating the specific implementation method for improving the optimal tip speed ratio control. Detailed Implementation

[0043] 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0044] Example 1

[0045] like Figure 1 This embodiment provides a wind turbine tip speed ratio control and simulation method with reference speed correction, applicable to large wind turbine units. This method balances three major control objectives: wind energy capture efficiency, grid-connected active power fluctuations, and turbine shaft mechanical load, while also adapting to turbine performance degradation and changes in ambient air density. By improving the optimal tip speed ratio control, its advantages are leveraged while avoiding its disadvantages.

[0046] The method in this embodiment is as follows:

[0047] Detecting real-time wind speed near the rotor plane of a wind turbine The ideal optimal speed reference value for a wind turbine is obtained by calculating the optimal tip speed ratio of the wind turbine. Further use Multiply by the gear ratio of the transmission system's gearbox (if it is a direct-drive wind turbine). =1), to obtain the ideal generator theoretical optimal speed reference value , then add a parameter T to a quantitatively designed first-order low-pass filter , add a limiter after the first-order low-pass filter, the upper limit value of the limiter is the rated speed of the generator , the lower limit value of the limiter is the grid-connected speed of the generator , take the output value of the limiter as the actual speed reference value of the generator , and construct a speed closed loop with the actual speed of the generator and the actual speed of the generator to obtain the generator torque reference value , and apply the generator torque control through the wind turbine converter, which can adopt mature control strategies such as rotor flux oriented vector control and stator voltage oriented vector control. Through simulation test, the improved optimal tip speed ratio control can obtain steady and dynamic control effect comparable to optimal torque control or power signal feedback control, while playing the advantages of optimal tip speed ratio control in automatically adapting to unit performance degradation and environmental changes, and the parameters of the speed loop PI regulator are easy to design.

[0048] wherein the first-order low-pass filter adopts the form of , wherein the design formula of the filter parameter is

[0049] (1)

[0050] wherein is the normalized equivalent moment of inertia of the wind turbine, and the calculation method is to take the rated power of the wind turbine as the power reference value (unit: watt), take the rated speed of the wind turbine as the speed reference value of the wind turbine (unit: rad / s), assume that the gear ratio of the gearbox in the transmission system is , then the speed reference value of the generator is , then the reference value of the moment of inertia of the wind turbine is , the reference value of the moment of inertia of the generator is , then the normalized equivalent moment of inertia of the wind turbine is , wherein is the nominal value of the moment of inertia of the wind turbine (unit: ), is the nominal value of the moment of inertia of the generator (unit: ).

[0051] is the speed normalized value of the generator in the wind turbine, , It is the actual speed of the generator (with a nominal value).

[0052] It is a constant coefficient determined by the parameters of the wind turbine. ,in, It is air density. It is the radius of the wind turbine blade. C pmax This represents the maximum wind energy utilization coefficient of the wind turbine. λ opt The optimal tip speed ratio.

[0053] Although the optimal torque coefficient is also used in the parameter design of the low-pass filter. Furthermore, this coefficient is also affected by the deterioration of unit performance and air density, but in this technology... It only slightly affects the dynamic power tracking performance of the unit, while the static optimal operating point of the unit can be effectively guaranteed. That is, the static optimal operating point of the unit will not be affected by changes in ambient air density, nor by the aerodynamic characteristics deterioration caused by the aging of the wind turbine.

[0054] Specifically, if the wind turbine's anemometer measures the wind speed at a certain distance directly in front of the turbine... (For example, using laser wind radar), a delay algorithm should also be used to... Converted to real-time wind speed near the wind turbine rotor plane Then, the aforementioned techniques are applied. The method for wind speed conversion is... ,in It is the time required for the wind speed measured by the wind measuring device to travel from the plane to the wind turbine plane.

[0055] like Figure 2 This is a practical application of the wind turbine tip speed ratio control and simulation method with reference speed correction. The speed loop PI is connected to the torque loop PI, and the torque loop PI is connected to the current loop PI. The speed closed-loop control and current inner loop control are achieved by applying generator torque through the converter.

[0056] In this method, the tip speed ratio control is achieved through speed control and torque control using existing technologies.

[0057] This method balances the three major control objectives of wind energy capture efficiency, active power fluctuations during grid connection, and mechanical load on the generator shaft system, while also adapting to generator performance degradation and changes in ambient air density. Improvements are made to the optimal tip speed ratio control, leveraging its advantages while avoiding its disadvantages.

[0058] Example 2

[0059] See Figure 3, on the basis of Embodiment 1, the present application provides a first-order low-pass filter with variable filter time constant T, as the first-order low-pass filter in Embodiment 1. Specifically, at the input of the low-pass filter the output of the low-pass filter obtained by feedback is subtracted, the difference is divided by the variable filter time constant T, and then the output of the low-pass filter is obtained through an integrator (denoted by ). .

[0060] The implementation principle of the first-order low-pass filter with variable filter time constant can be represented by formula (2):

[0061] (2)

[0062] Embodiment 3

[0063] The present embodiment provides an electronic device, comprising: one or more processors and a memory, the memory having one or more programs stored therein, the one or more programs comprising instructions for performing the wind turbine tip speed ratio control and simulation method with reference speed correction as described in Embodiment 1.

[0064] Embodiment 4

[0065] The present embodiment provides a computer-readable storage medium comprising one or more programs for execution by one or more processors of an electronic device, the one or more programs comprising instructions for performing the wind turbine tip speed ratio control and simulation method with reference speed correction as described in Embodiment 1.

[0066] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for controlling and simulating the tip speed ratio of a wind turbine blade with reference speed correction, characterized in that, Includes the following steps: Based on the real-time wind speed and optimal tip speed ratio of the wind turbine, the theoretical optimal speed reference value of the generator is obtained. The theoretical optimal speed reference value of the generator is input into a low-pass filter. After filtering and limiting, the actual speed reference value of the generator is obtained, thereby realizing dynamic correction of the reference speed. Based on the actual generator speed reference value and the actual generator speed, a closed-loop speed control is constructed, and a generator torque reference value is calculated. Based on the generator torque reference value, generator torque control is applied. Tip speed ratio control is achieved through speed control and torque control. The expression for the low-pass filter is: in, The per-unit equivalent moment of inertia of the wind turbine. It is the per-unit value of the generator speed in a wind turbine. It is a coefficient determined by the parameters of the wind turbine. air density, The radius of the wind turbine blade. C pmax This represents the maximum wind energy utilization coefficient of the wind turbine. λ opt The optimal tip speed ratio.

2. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The acquisition of real-time wind speed includes the following steps: Wind speed information from the anemometer is obtained, and the real-time wind speed is obtained through a delay algorithm.

3. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 2, characterized in that, The delay algorithm is implemented using the following formula: in, For real-time wind speed, The wind speed measured by the anemometer. It is the time required for the wind speed measured by the anemometer to travel from the plane of the wind turbine to the plane of the wind turbine. Represents a complex frequency.

4. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The aforementioned amplitude limit is specifically as follows: The upper limit of the limit is set at the generator's rated speed, and the lower limit is set at the generator's grid-connected speed.

5. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The process of obtaining the theoretical optimal speed reference value for the generator includes the following steps: Based on the real-time wind speed and the optimal tip speed ratio of the wind turbine, obtain the ideal reference value for the optimal wind turbine speed. Based on the optimal speed reference value of the wind turbine and the gear ratio of the transmission system gearbox, the theoretical optimal speed reference value of the generator is obtained.

6. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, Generator torque control is achieved based on the wind turbine converter.

7. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The equivalent moment of inertia is obtained using the following formula: in, The per-unit equivalent moment of inertia of the wind turbine. This refers to the rated speed of the wind turbine. This is the reference value for the generator's speed. This refers to the gear ratio of the gearbox in the transmission system. The rated power of the wind turbine unit. The moment of inertia of the wind turbine has a given value. This is the named value of the generator's moment of inertia.

8. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The per-unit speed of the generator in a wind turbine is obtained using the following formula: in, This represents the per-unit speed of the generator in a wind turbine unit. This is the actual speed of the generator. This is the reference speed value for the generator.

9. The method for controlling and simulating the tip speed ratio of a wind turbine with reference speed correction according to claim 1, characterized in that, The low-pass filter is a first-order low-pass filter with a variable time constant. The calculation process of the filter output includes: The difference between the input of the low-pass filter and the output of the low-pass filter obtained from feedback is calculated. The ratio of this difference to the variable filter time constant is then input into the integrator to obtain the filter output.

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