A method and system for controlling a wind turbine generator set under extreme wind conditions

Abstract

The present invention discloses a method and system for controlling a wind turbine generator set under extreme wind conditions, comprising the following steps: comparing a generator speed deviation with a generator speed difference judgment value; if the generator speed deviation is less than the generator speed difference judgment value, assigning the generator speed difference judgment value to a generator speed difference intermediate value; determining a generator speed change judgment value by judging the generator speed difference intermediate value; adjusting a wind turbine operation strategy by comparing an actual value of a speed nacelle vibration acceleration with a speed nacelle vibration acceleration threshold value, judging a timing for changing an operation instruction while issuing a power reduction operation instruction, and referencing a relationship between a pitch angle and a generator speed difference linear interpolation to ensure that a minimum generator speed difference is reduced while a possible pitch angle is increased; and adopting a generator speed judgment value to avoid the problem of poor control effect caused by an excessively large nacelle acceleration judgment portion.

Description

Technical Field

[0001] The present invention belongs to the field of wind turbine generator set control, and in particular relates to a method and system for controlling a wind turbine generator set under extreme wind conditions. Background Art

[0002] The rotor of a horizontal-axis wind turbine absorbs wind energy and rotates, in turn driving the connected generator to generate electricity. The control objectives of the wind turbine vary depending on wind speed. Above rated wind speed, the control objective is to maintain the turbine speed near the rated speed through pitch control, thereby maintaining the turbine output power near the rated power and ensuring that the mechanical and electrical components of the wind turbine operate normally within the designed range.

[0003] In some extreme wind conditions, the extreme loads on the turbine unit can be detrimental to wind turbine operation. Therefore, it's necessary to adjust the load control strategy to minimize turbine loads in extreme wind conditions, such as those with large wind direction and speed fluctuations. Conventional control methods primarily monitor real-time speed and, based on speed fluctuations, use PI or PID control to determine the corresponding pitch angle. The pitch angle can limit or absorb wind energy. However, the real-time speed is only compared with the reference speed as a control input, and the speed fluctuation trend is not considered. As a result, traditional turbine control methods cannot effectively prevent the occurrence of extreme loads. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a method for controlling a wind turbine generator set under extreme wind conditions. This method replaces the prior art solution that relies solely on measuring the turbine speed to schedule pitch control, thereby more specifically addressing the impact of extreme loads caused by rapid changes in wind speed and direction. The present invention uses real-time operating data on generator speed and nacelle acceleration to determine their changing trends and determine whether the turbine is experiencing extreme gust conditions. If so, the method limits wind energy absorption by reducing power or adjusting pitch, thereby reducing the extreme out-of-plane loads on large turbine components, such as the blade roots.

[0005] To achieve the above object, the present invention adopts a technical solution: a method for controlling a wind turbine generator set under extreme wind conditions, comprising the following steps:

[0006] Compare the generator speed deviation with the generator speed difference judgment value;

[0007] If the generator speed deviation is less than the generator speed difference judgment value, the generator speed difference judgment value is assigned to the generator speed difference middle value;

[0008] Determine whether the middle value of the generator speed difference is greater than 0: if the middle value of the generator speed difference is greater than 0, the generator speed change judgment value is assigned to 0; if the middle value of the generator speed difference is less than 0, the generator speed change judgment value is the inverse of the middle value of the generator speed difference;

[0009] Comparing the actual value of the speed cabin vibration acceleration with the speed cabin vibration acceleration threshold: if the actual value of the speed cabin vibration acceleration is less than the speed cabin vibration acceleration threshold, the control process ends; if the actual value of the speed cabin vibration acceleration is greater than the speed cabin vibration acceleration threshold, a power reduction operation instruction is issued, and the load control action time and monitoring amount are set and determined;

[0010] When the monitored amount reaches or determines the load control action time, the control process ends.

[0011] Furthermore, through the one-to-one correspondence between the speed nacelle vibration acceleration threshold and the blade pitch position angle pitch, the real-time speed change pitch angle threshold speed nacelle vibration acceleration threshold is obtained, and the wind turbine blade pitch position angle pitch is directly obtained through the sensor.

[0012] Furthermore, the generator speed deviation = the real-time generator speed - the generator speed set point, and the generator speed deviation is assigned to the generator speed difference middle value.

[0013] Furthermore, the generator speed difference judgment value omega_errl is calculated by the wind turbine blade pitch position angle pitch and linear interpolation parameters a and b, specifically: omega_errl = a*pitch+b, where a and b are constants.

[0014] Furthermore, the actual value of the speed nacelle vibration acceleration is the product of the generator speed change judgment value and the nacelle acceleration judgment value; it is obtained by the following method: the nacelle acceleration is detected. If the nacelle acceleration Nacc is less than 0, the nacelle acceleration judgment value is 0; if the nacelle acceleration is greater than 0, the nacelle acceleration judgment value = nacelle acceleration.

[0015] Furthermore, actual wind speed, wind direction detected by an anemometer, generator power, pitch angle, and pitch rate are used as parameters to judge extreme wind conditions.

[0016] Furthermore, the power can be reduced by superimposing the pitch rate on the original pitch rate instruction to perform pitch control, performing power limiting operation at a set rate, reducing the generator speed, or performing yaw control operation.

[0017] Furthermore, the load control action time is determined by setting the accumulation time, power limit or pitch limit.

[0018] At the same time, a wind turbine generator set control system is provided, which adopts the method for controlling a wind turbine generator set under extreme wind conditions described in the present invention.

[0019] A wind turbine generator set may also be provided, which adopts the wind turbine generator set control system of the present invention.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] The present invention uses the changing trend of generator speed and cabin acceleration as control inputs, and determines whether extreme gust conditions have occurred by judging their relationship with a threshold value; the relationship between pitch angle and generator speed difference is referenced by linear interpolation to ensure that the minimum generator speed difference is reduced while the possible pitch angle is increased; the generator speed difference judgment value is adopted to avoid an excessively large cabin acceleration judgment part, resulting in poor control effect; the overall power reduction method is adopted to protect the safe operation of the unit; and multiple control indicators can be used to judge the action time of load control, so as to more specifically solve the influence of extreme load caused by rapid changes in wind speed and wind direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] The numbering of the steps in the present invention is only for the convenience of explanation and is not intended to limit the specific order of the steps. A person skilled in the art will know which steps must be performed in sequence. The present invention provides a method for controlling a wind turbine generator set under extreme wind conditions, with reference to Figure 1 , including the following steps:

[0025] S1, detect the wind turbine generator generation operation flag. This method only operates in the power generation condition, so it is determined whether the flag is 1;

[0026] S2: If the flag is not 1, it means that the unit is not generating electricity and the control process ends;

[0027] S3, if the flag is 1, the control process starts; it can also directly start executing the following steps in a known running state;

[0028] S4, detecting the pitch angle of the wind turbine blades;

[0029] S5, obtaining the speed nacelle vibration acceleration threshold omega_Nacc_threshold, where the threshold has a one-to-one correspondence with the blade pitch position angle pitch;

[0030] S6, through the blade pitch position angle pitch obtained in S4, finds the speed change pitch angle threshold speed cabin vibration acceleration threshold omega_Nacc_threshold at this time; as another example, the present invention adopts a method of using the pitch angle table lookup to obtain the judgment threshold, considering that the pitch angle detection is more reliable and accurate under strong wind conditions; but the judgment threshold can also be obtained by obtaining the wind speed and power as a lookup table.

[0031] S7, detect the generator speed omega;

[0032] S8, detecting the generator speed set point omega_sp; the generator speed set point can be directly assigned.

[0033] S9, subtracting the generator speed set point omega_sp obtained in S8 from the generator speed omega obtained in S7, thereby obtaining the generator speed deviation omega_err;

[0034] S10, assigning the generator speed deviation omega_err to the generator speed difference intermediate value omega_errm;

[0035] S11, obtaining linear interpolation parameters a and b;

[0036] S12, calculate the generator speed difference judgment value omega_errl from the wind turbine blade pitch position angle pitch obtained in S4 and a and b obtained in S11, using the formula omega_errl = a*pitch+b;

[0037] S13, judging whether the generator speed deviation omega_err obtained in S9 is less than the generator speed difference judgment value omega_errl obtained in S12;

[0038] S14, if the generator speed deviation omega_err is less than the generator speed difference judgment value omega_errl, the generator speed difference judgment value omega_errl is assigned to the generator speed difference intermediate value omega_errm;

[0039] S15, determining whether the generator speed difference intermediate value omega_errm is greater than 0;

[0040] S16, if the generator speed difference intermediate value omega_errm is greater than 0, the generator speed change judgment value omega_m is set to 0;

[0041] S17, if the generator speed difference intermediate value omega_errm is less than 0, the generator speed change judgment value is inverted omega_m = -omega_errm;

[0042] S18, detecting cabin acceleration Nacc;

[0043] S19, determining whether the cabin acceleration Nacc is greater than 0;

[0044] S20, if the cabin acceleration Nacc is less than 0, the cabin acceleration judgment value Naccm=0;

[0045] S21, if the cabin acceleration Nacc is greater than 0, the cabin acceleration judgment value Naccm=Nacc;

[0046] S22, multiplying the generator speed change judgment value omega_m obtained in S17 by the nacelle acceleration judgment value Naccm obtained in S21 to calculate the actual calculated value of the speed nacelle vibration acceleration omega_Nacc_cal;

[0047] S23, determining whether the actual calculated value of the speed cabin vibration acceleration omega_Nacc_cal is greater than the omega_Nacc_threshold obtained in S6;

[0048] S24, if omega_Nacc_cal is less than omega_Nacc_threshold, the control flow ends;

[0049] S25. If omega_Nacc_cal is greater than omega_Nacc_threshold, the speed-pitch controller gives a pitch rate of 2 degrees per second superimposed on the original pitch rate instruction or performs power limiting operation at a rate of -300 kilowatts per second; as an optional embodiment, the adjustment operation mode described in S25 can also be replaced by reducing the generator speed or performing yaw control.

[0050] S26, start timing at the same time, starting with time = 0, and accumulating time with cycle as the step length;

[0051] S27, obtaining the dead time setting parameter Durationtime;

[0052] S28, determining whether the accumulated time time is greater than the dead time setting parameter Durationtime;

[0053] S29, if time is greater than Durationtime, it means that the load control action time domain has expired, the control process ends, and time is set to 0;

[0054] S30: If it is determined that time is less than Durationtime, it means that the load control action time domain has not yet expired, and time continues to accumulate.

[0055] In S26 to S30, the accumulated time is used as the judgment basis, and a power limit or a pitch limit can also be given. When the power or pitch angle reaches or exceeds the limit, it means that the load control action time domain has expired and the control process ends.

[0056] During implementation, the control method of the present invention can be used to improve the control system of existing wind turbine generator sets and in the control system of newly built sets.

[0057] At the same time, the control system of the present invention can be implemented together with a wind turbine generator set, and the wind turbine generator set adopts the wind turbine generator set control system of the present invention.

[0058] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for controlling a wind turbine generator set under extreme wind conditions, characterized in that: The following steps are involved: Compare the generator speed deviation with the generator speed difference judgment value; If the generator speed deviation is less than the generator speed difference judgment value, the generator speed difference judgment value is assigned to the generator speed difference middle value; Determine whether the middle value of the generator speed difference is greater than 0: if the middle value of the generator speed difference is greater than 0, the generator speed change judgment value is assigned to 0; if the middle value of the generator speed difference is less than 0, the generator speed change judgment value is the inverse of the middle value of the generator speed difference; Comparing the actual value of the speed cabin vibration acceleration with the speed cabin vibration acceleration threshold: if the actual value of the speed cabin vibration acceleration is less than the speed cabin vibration acceleration threshold, the control process ends; if the actual value of the speed cabin vibration acceleration is greater than the speed cabin vibration acceleration threshold, a power reduction operation instruction is issued, and the load control action time and monitoring amount are set and determined; When the monitored quantity reaches or determines the load control action time, the control process ends; the generator speed difference judgment value omega_errl is calculated by the wind turbine blade pitch position angle pitch and the linear interpolation parameters a and b, specifically: omega_errl=a*pitch+b, a and b are constants; the actual value of the speed cabin vibration acceleration is the product of the generator speed change judgment value and the cabin acceleration judgment value; it is obtained by the following method: detect the cabin acceleration, if the cabin acceleration Nacc is less than 0, the cabin acceleration judgment value is 0, if the cabin acceleration is greater than 0, the cabin acceleration judgment value = cabin acceleration.

2. The method for controlling a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: The real-time speed change pitch angle threshold speed nacelle vibration acceleration threshold is obtained through the one-to-one correspondence between the speed nacelle vibration acceleration threshold and the blade pitch position angle pitch. The wind turbine blade pitch position angle pitch is directly obtained through the sensor.

3. The method for controlling a wind turbine generator set under extreme wind conditions according to claim 1, wherein: Generator speed deviation = real-time generator speed - generator speed set point, and then the generator speed deviation is assigned to the middle value of the generator speed difference.

4. The method for controlling a wind turbine generator set under extreme wind conditions according to claim 1, wherein: The actual wind speed, wind direction detected by anemometer, generator power, pitch angle and pitch rate are used as parameters to judge extreme wind conditions.

5. The method for controlling a wind turbine generator set under extreme wind conditions according to claim 1, wherein: The power reduction method includes superimposing the pitch rate on the original pitch rate instruction to change the pitch, performing power limiting operation at a set rate, reducing the generator speed or performing yaw control operation.

6. The method for controlling a wind turbine generator set under extreme wind conditions according to claim 1, characterized in that: The load control action time is determined by setting the accumulation time, power limit or pitch limit.

7. A wind turbine generator control system, characterized in that: A method for controlling a wind turbine generator set under extreme wind conditions as described in any one of claims 1 to 6 is adopted.

8. A wind turbine generator set, characterized in that: The wind turbine generator control system according to claim 7 is adopted.

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