A wind turbine generator set rotating speed fluctuation identification and variable pitch control method

Abstract

The application provides a wind turbine rotating speed fluctuation identification and variable pitch control method, comprising the following steps: obtaining a first advance variable pitch starting power and a maximum advance variable pitch angle; continuously detecting and obtaining wind speed, generator rotating speed, variable pitch angle and real-time power with a sampling interval lower than 100 ms and a period of 10 min; performing rotating speed fluctuation identification to determine whether the rotating speed fluctuation is caused by advance variable pitch control based on power; controlling and optimizing the advance variable pitch; calculating characteristic quantities based on swept wind area; simulating at different variable pitch angles based on stable wind to obtain advance variable pitch gain based on power; obtaining a second advance variable pitch starting power based on the advance variable pitch gain, and replacing the first advance variable pitch starting power with the second advance variable pitch starting power. The method identifies the fluctuation caused by the advance variable pitch control algorithm based on power under low turbulence conditions according to the rotating speed, variable pitch angle and power, and solves the fluctuation problem caused by the advance variable pitch control based on power.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to a method for identifying wind turbine generator speed fluctuations and pitch control. Background Technology

[0002] As the wind power industry develops, competition is becoming increasingly fierce, with turbine manufacturers continuously launching wind turbine generators with longer blades and taller towers. Driven by cost considerations, load control of the entire turbine is becoming increasingly refined, such as addressing load issues near rated operating conditions.

[0003] To address the issue of excessive load on variable-speed, variable-pitch wind turbines near their rated operating conditions, the industry commonly employs a pre-adjustment pitch control method. This load-reducing control method typically uses the average power output over a period of time as input to adjust the pitch angle in advance.

[0004] In actual operation, when the external energy input is relatively stable, the following will occur: 1) Power increases, pitch adjustment and retraction; 2) Due to pitch adjustment and retraction, wind energy absorption decreases, resulting in a power reduction; 3) Power decreases, pitch adjustment and opening; 4) Due to pitch adjustment and opening, wind energy absorption increases, pitch adjustment and retraction. Due to power lag, steps 1-4 cycle repeatedly, resulting in speed fluctuations, typically periodic low-frequency fluctuations. This phenomenon is particularly pronounced in long-bladed turbine units.

[0005] This periodic fluctuation will accelerate fatigue damage to components such as towers and elastic supports. Summary of the Invention

[0006] In view of this, the problem to be solved by the present invention is to provide a method for identifying and controlling the speed fluctuation of a wind turbine generator set. The method identifies fluctuations that occur under low turbulence conditions due to the influence of factors such as the power pre-pitch control algorithm based on the speed, pitch angle and power, and solves the fluctuation problem caused by the power pre-pitch control.

[0007] The present invention solves the above-mentioned technical problems through the following technical means: The present invention provides a method for identifying wind turbine generator speed fluctuations and pitch control, comprising the following steps:

[0008] Obtain the initial power of the first advance pitch and the maximum advance pitch angle;

[0009] With a sampling interval of less than 100ms and a cycle of 10min, continuous detection is performed to acquire wind speed, generator speed, pitch angle and real-time power.

[0010] Perform speed fluctuation identification to determine whether the speed fluctuation is caused by power-based advance pitch control. If so, proceed to the next step; otherwise, return to the first step and re-determine.

[0011] If the speed fluctuation is caused by power-based advance pitch control, then the advance pitch control is optimized.

[0012] Calculate characteristic quantities based on swept area;

[0013] Based on stable wind, simulations at different pitch angles yielded power-based advance pitch gain.

[0014] The second advance pitch starting power is obtained based on advance pitch gain calculation, and the first advance pitch starting power is replaced with the second advance pitch starting power.

[0015] Furthermore, it also includes comparing the real-time power with the first advance pitch power and comparing the pitch angle with the advance pitch angle. If the real-time power < first advance pitch activation power PowerOn*0.9 and / or pitch angle > advance pitch maximum angle PitchMax+1, then the advance pitch starting power is restored to the first advance pitch activation power.

[0016] Furthermore, speed fluctuation identification also includes:

[0017] By analyzing the frequency spectrum of the rotational speed, a significant frequency f below 1P is obtained, with a period of Y = 1 / f.

[0018] Calculate turbulence intensity:

[0019] Divide the data into 10-minute intervals with interval T, and collect the data within each interval T:

[0020] The times for obtaining the maximum and minimum RPMs are: MotorspeedMaxT; MotorspeedMinT;

[0021] The times for obtaining maximum and minimum power are: PowerMaxT; PowerMinT;

[0022] The times for obtaining the maximum and minimum pitch angles are: PitchPostionMaxT; PitchPostionMinT;

[0023] Calculate the time intervals between the maximum / minimum speed and the maximum / minimum pitch angle, and between the maximum power and the maximum pitch angle, respectively:

[0024] ΔMotorspeedToPitchpositon=(PitchPostionMaxT-MotorspeedMaxT) / 2+(PitchPostionMinT-MotorspeedMinT) / 2;

[0025] ΔPowerToPitchpositon = (PitchPostionMaxT - PowerMaxT) / 2 + (PitchPostionMinT - PowerMin) / 2;

[0026] Calculate the average values ΔPowerToPitchpositon and ΔMotorspeedToPitchpositon of the phase differences between the pitch angle and power, and between the pitch angle and rotational speed respectively according to the above formula;

[0027] If the following conditions are simultaneously met: ΔMotorspeedToPitchpositonAvg > 0.05 * T > ΔPowerToPitchpositonAvg, the pitch angle < PitchMax + 1, the real-time power > PowerOn * 0.9, and the wind speed turbulence is less than the set value; then it can be determined that the rotational speed fluctuation is caused by the power-based early pitch control.

[0028] Furthermore, the set value is 60% - 80% of the IEC standard Class C turbulence.

[0029] Furthermore, based on the swept area S, calculate the characteristic quantity δ = S * S / 1000 / 1000.

[0030] Furthermore, the power-based early pitch gain is the slope of the fitting curve obtained by fitting the pitch angle and power through simulation of the stable wind conditions at different pitch angles.

[0031] Furthermore, calculating the second early pitch power based on the early pitch gain Kptp includes: the starting power of the second early pitch = rated power - ceil(δ * Kptp) * the maximum pre-pitch angle PitchMax.

[0032] As can be seen from the above technical solution, the beneficial effects of the present invention are as follows: The present invention provides a method for identifying wind turbine generator speed fluctuations and pitch control, including the following steps: obtaining the first advance pitch control starting power and the maximum advance pitch control angle; continuously detecting and obtaining wind speed, generator speed, pitch angle, and real-time power with a sampling interval of less than 100ms and a period of 10min; identifying speed fluctuations and determining whether the speed fluctuations are caused by power-based advance pitch control; if so, proceeding to the next step; otherwise, returning to the first step to re-determine; if the speed fluctuations are caused by power-based advance pitch control, optimizing the pre-pitch control; calculating characteristic quantities based on swept area; deriving the power-based advance pitch gain based on simulations under different pitch angles in stable wind conditions; calculating the second advance pitch control starting power based on the advance pitch gain, and replacing the first advance pitch control starting power with the second advance pitch control starting power. This method identifies fluctuations occurring in low-turbulence conditions due to the influence of power-based pre-pitch control algorithm factors based on speed, pitch angle, and power, thus solving the fluctuation problem caused by power pre-pitch control. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0034] Figure 1 This is a schematic diagram of the speed fluctuation identification process of the present invention;

[0035] Figure 2 This is a schematic diagram of the pitch control process of the present invention. Detailed Implementation

[0036] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0037] Please see Figures 1-2 As shown, the present invention provides a method for identifying wind turbine generator speed fluctuations and controlling pitch, comprising the following steps:

[0038] The system obtains the initial power (PowerOn) for early pitch control and the maximum pitch angle (PitchMax). In practical applications, the wind turbine's mapping is first obtained. This mapping includes the hub thrust mapping under over-power conditions, the turbine power mapping under over-power conditions, and the hub thrust limit boundary. Based on the obtained wind turbine mapping, the initial power (PowerOn) for early pitch control is then obtained. The initial power (PowerOn) is the power required to activate early pitch control, and it is less than the wind turbine's rated power.

[0039] With a sampling interval of less than 100ms, 10 minutes of data are acquired to determine whether low-frequency fluctuations exist, and to calculate the fluctuation frequency and fluctuation period. With a period of 10 minutes, continuous detection is performed to acquire wind speed, generator speed, pitch angle and real-time power.

[0040] The system identifies speed fluctuations and determines whether they are caused by power-based advance pitch control. If so, it proceeds to the next step; otherwise, it returns to the first step to re-evaluate. Since both pitch angle and power are controlled based on speed as input, under normal circumstances, the trends of pitch angle and power change are consistent with the speed.

[0041] Specifically, by analyzing the frequency spectrum of the rotational speed, a significant frequency f below 1P is obtained, with a period of Y = 1 / f. During normal operation of the unit, continuous rotation will generate periodic excitation. If an excitation is generated for each rotation, the corresponding frequency is 1P.

[0042] Calculate turbulence intensity:

[0043] Divide the data into 10-minute intervals with interval T, and collect the data within each interval T:

[0044] The times for maximum and minimum engine speeds are obtained separately: MotorspeedMaxT and MotorspeedMinT;

[0045] The times for obtaining maximum power and minimum power are PowerMaxT and PowerMinT, respectively.

[0046] The times for obtaining the maximum and minimum pitch angles are PitchPostionMaxT and PitchPostionMinT, respectively.

[0047] Calculate the time intervals between the maximum / minimum speed and the maximum / minimum pitch angle, and between the maximum power and the maximum pitch angle, respectively:

[0048] ΔMotor speed To Pitch position = (Pitch Position Max T - Motor speed Max T) / 2 + (Pitch Position Min T - Motor speed Min T) / 2;

[0049] ΔPower To Pitch position = (Pitch Position Max T - Power Max T) / 2 + (Pitch Position Min T - Power Min) / 2; Calculate the average value over 10 minutes, and obtain the phase difference between the pitch angle and power by finding the average value of the time difference;

[0050] Calculate the average values of the phase differences ΔPower To Pitch position and ΔMotor speed To Pitch position between the pitch angle and power, and between the pitch angle and speed respectively according to the above formulas;

[0051] If all of the following conditions are met simultaneously: ΔMotor speed To Pitch position Avg > 0.05 * T > ΔPower To Pitch position Avg, pitch angle < Pitch Max + 1, real-time power > Power On * 0.9, and wind speed turbulence is less than the set value; the set value is 60% - 80% of the IEC standard Class C turbulence. Preferably, the set value is 70% of the IEC standard Class C turbulence.

[0052] During normal operation, the pitch angle and speed are in phase, and there is no obvious trend relationship with power. By judging the phase difference relationship, if the relationship between power and pitch angle is more correlated; it can be determined that the speed fluctuation is caused by the pitch control in advance based on power;

[0053] If the speed fluctuation is caused by the pitch control in advance based on power, then optimize the pre-pitch control;

[0054] Calculate the characteristic quantity based on the swept area; specifically, based on the swept area S, calculate the characteristic quantity δ = S * S / 1000 / 1000.

[0055] Based on the steady wind, simulations at different pitch angles are carried out to obtain the pitch control in advance gain Kptp based on power; specifically, the pitch control in advance gain based on power is the slope of the fitting curve obtained by fitting the pitch angle and power for the steady wind conditions simulations at different pitch angles.

[0056] The second advance pitch starting power is obtained based on the advance pitch gain calculation, and the first advance pitch starting power is replaced with the second advance pitch starting power; specifically, the second advance pitch starting power = rated power - ceil(δ*Kptp)*maximum pre-pitch angle PitchMax.

[0057] The real-time power is compared with the first advance pitch power, and the pitch angle is compared with the advance pitch angle. If the real-time power < first advance pitch activation power PowerOn*0.9 and / or pitch angle > advance pitch maximum angle PitchMax+1, then the advance pitch starting power is restored to the first advance pitch activation power. Based on power, speed, and pitch angle, it is identified whether a power-based advance pitch algorithm is causing speed fluctuations, and then low-frequency speed fluctuations are resolved by adaptively adjusting parameters.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for identifying speed fluctuations and controlling pitch in a wind turbine generator set, characterized in that: Includes the following steps: Obtain the initial power of the first advance pitch and the maximum advance pitch angle; With a sampling interval of less than 100ms and a cycle of 10min, continuous detection is performed to acquire wind speed, generator speed, pitch angle and real-time power. Perform speed fluctuation identification to determine whether the speed fluctuation is caused by power-based advance pitch control. If so, proceed to the next step; otherwise, return to the first step and re-determine. If the speed fluctuation is caused by power-based advance pitch control, then the advance pitch control is optimized. Calculate characteristic quantities based on swept area; Based on stable wind, simulations at different pitch angles are used to obtain power-based advance pitch gain. The second advance pitch starting power is obtained by calculating the advance pitch gain based on power, and the first advance pitch starting power is replaced by the second advance pitch starting power.

2. The method for identifying wind turbine generator speed fluctuations and controlling pitch according to claim 1, characterized in that, It also includes comparing the real-time power with the first advance pitch power and comparing the pitch angle with the advance pitch angle. If the real-time power < first advance pitch activation power PowerOn*0.9 and / or pitch angle > advance pitch maximum angle PitchMax+1, then the advance pitch starting power is restored to the first advance pitch activation power.

3. The method for identifying wind turbine generator speed fluctuations and controlling pitch according to claim 2, characterized in that, The process of identifying speed fluctuations also includes: By analyzing the frequency spectrum of the rotational speed, a significant frequency f below 1P is obtained, with a period of Y = 1 / f. Calculate turbulence intensity: Divide the data into 10-minute intervals with interval T, and collect the data within each interval T: The times for obtaining the maximum and minimum RPMs are: MotorspeedMaxT; MotorspeedMinT; The times for obtaining maximum and minimum power are: PowerMaxT; PowerMinT; The times for obtaining the maximum and minimum pitch angles are: PitchPostionMaxT; PitchPostionMinT; Calculate the time intervals between the maximum / minimum speed and the maximum / minimum pitch angle, and between the maximum power and the maximum pitch angle, respectively: ΔMotorspeedToPitchpositon=(PitchPostionMaxT-MotorspeedMaxT) / 2+(PitchPostionMinT-MotorspeedMinT) / 2; ΔPowerToPitchpositon=(PitchPostionMaxT-PowerMaxT) / 2+(PitchPostionMinT-PowerMin) / 2; Based on the above formulas, calculate the average values ​​of the phase difference between pitch angle and power, and between pitch angle and speed, ΔPowerToPitchpositon and ΔMotorspeedToPitchpositon respectively. If the following conditions are simultaneously met: ΔMotorspeedToPitchpositonAvg > 0.05 * T > ΔPowerToPitchpositonAvg, the pitch angle < PitchMax + 1, the real-time power > 0.9 * PowerOn, and the wind speed turbulence is less than the set value; it can be determined that the rotational speed fluctuation is caused by the power-based early pitch control.

4. The wind turbine generator speed fluctuation identification and pitch control method according to claim 3, characterized in that, The set value is 60% - 80% of the IEC standard Class C turbulence.

5. The method for identifying wind turbine generator speed fluctuations and controlling pitch according to claim 1, characterized in that, Based on the swept area S, calculate the characteristic quantity δ = S * S / 1000 / 1000.

6. The method for identifying wind turbine generator speed fluctuations and controlling pitch according to claim 5, characterized in that, The power-based early pitch gain is the slope of the fitting curve obtained by fitting the pitch angle and power based on the simulation of the steady wind conditions at different pitch angles.

7. The wind turbine generator speed fluctuation identification and pitch control method according to claim 6, characterized in that, Calculating the second early pitch power based on the early pitch gain Kptp includes: The starting power of the second early pitch = rated power - ceil(δ * Kptp) * the maximum pre-pitch angle PitchMax.

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