A wind turbine generator system and method for resonant ride-through before grid connection

Abstract

The application discloses a wind turbine generator system and a resonance crossing method and system before grid connection, comprising: determining the tower inherent frequency of the system and the corresponding coupling frequency rotation speed; determining the rotation speed resonance region according to the coupling frequency rotation speed point; judging whether the system has the fast crossing ability; and the system fast crosses the resonance region. The application can avoid the wind turbine generator system from being resonated by the rotation frequency and the tower before grid connection, and improve the service life of the system. The grid connection signal of the system does not only depend on the average wind speed of the anemometer, and the system keeps the grid connection state at any time when the wind speed is lower than the cut-in wind speed, and the system is quickly connected to the grid when the grid connection ability is achieved through the operation state of the system, so that the grid connection efficiency is effectively improved, the failure rate of the system is reduced, and the power generation hours under the low wind speed condition are improved. The application is simple to implement, and does not need additional sensors and hardware.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind power generation, and particularly to a wind turbine generator system pre-grid resonance crossing method and system, a storage medium and a computing device. BACKGROUND

[0002] In recent years, with the vigorous development of renewable energy, in order to control the load and cost of the wind turbine generator system, the inherent frequency coupling point of the tower is avoided in the operating speed (grid-connected speed to rated speed) of the unit, resulting in that there will be a coupling point between the rotor speed and the inherent frequency of the tower before the grid-connected speed of the wind turbine generator system. In the traditional control process, the historical average wind speed is used as the judgment condition for starting and grid-connecting, and when the average wind speed is greater than the set cut-in wind speed, the unit is started and grid-connected. The actual wind speed is fluctuant, and when the wind condition is maintained for a long time, the speed frequency is in the coupling range of the inherent frequency of the tower, that is, in the resonance region of the speed, resonance phenomenon may occur.

[0003] The traditional resonance region crossing method mainly acts on the unit after grid connection, and avoids the resonance risk by limiting power or limiting torque, so as to avoid the unit staying in the speed forbidden zone for a long time. The method is not applicable to the resonance of the grid-connected speed and the tower.

[0004] For the resonance phenomenon before grid connection, the cut-in wind speed, the grid-connected speed and the opening pitch rate can be increased to make the unit quickly pass through the resonance region. However, increasing the cut-in wind speed and the grid-connected speed will lose the power generation hours in the low wind speed section, and the opening pitch rate is affected by the wind condition and cannot guarantee to quickly pass through the resonance region.

[0005] In summary, the existing control method does not consider the resonance of the tower and the speed frequency before grid connection, and the strategy of limiting torque and power at a constant speed after grid connection is not applicable before grid connection. The existing technology uses the average wind speed as the unit cut-in condition, which cannot avoid the long-time operation of the unit in the speed resonance, increases the resonance risk of the unit, and affects the service life of the unit. SUMMARY

[0006] The first object of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide a safe and reliable wind turbine generator system pre-grid resonance crossing method, which fills the gap in the processing method of avoiding resonance before the wind turbine generator system is grid-connected.

[0007] The second object of the present application is to provide a wind turbine generator system pre-grid resonance crossing system.

[0008] The third object of the present application is to provide a storage medium.

[0009] The fourth object of the present application is to provide a computing device.

[0010] The first object of the application is achieved by the following technical solution: a wind turbine group pre-grid resonance crossing method, comprising the following steps:

[0011] 1) Determine the tower natural frequency of the unit and its corresponding coupling frequency speed;

[0012] 2) Determine the speed resonance region according to the coupling frequency speed point;

[0013] 3) If the current nacelle wind speed is greater than the set value, start normally, if less than, execute step 4);

[0014] 4) Determine whether the unit has fast crossing capability, at this time the lower boundary of the speed resonance region is set as the target value, when the unit speed reaches the lower boundary of the speed resonance region and remains stable, calculate the estimated wind speed of the current unit, and determine whether the optimal absorbed power under the estimated wind speed is greater than the preset threshold, if greater than, consider that the unit has fast crossing capability, execute step 5), if it is determined that the unit does not have fast crossing capability, continue to keep the lower boundary of the speed resonance region as the target value, and when the absorbed power is greater than the preset threshold, perform crossing;

[0015] 5) Change the target value to grid-connected speed, add an additional pitch bias in the pitch controller of the unit to make the unit pitch fast to cross the speed, and start timing, if the unit speed is greater than the upper boundary of the speed resonance region within a specified time, then complete the pre-grid resonance crossing, if the unit speed is still within the speed resonance region, i.e. less than the upper boundary of the speed resonance region, cancel the pitch bias, repeat steps 4), 5), until the unit speed is greater than the upper boundary of the speed resonance region within a specified time, complete the pre-grid resonance crossing.

[0016] Further, in step 1), the nacelle lateral vibration acceleration data of the unit is obtained, the nacelle lateral vibration acceleration data is grouped, and the nacelle lateral vibration acceleration data of each group is subjected to Fourier transform to obtain frequency domain data of each group. The characteristic frequency between the rated speed one times the frequency and the rated speed three times the frequency is compared with the modal tower frequency in the simulation, and the characteristic frequency with a deviation within a preset range from the modal tower frequency is selected as the tower natural frequency.

[0017] Further, in step 1), the coupling frequency speed corresponding to the tower natural frequency is calculated according to the following formula:

[0018]

[0019] In the formula, ω coupfre is the coupling frequency speed, f tower is the tower natural frequency.

[0020] Further, in step 2), the upper and lower boundaries of the rotational speed resonance region are both multiples of the coupling frequency rotational speed, i.e. [a*ω coupfre b*ω coupfre ], a < 1, b > 1, wherein ω coupfre is the coupling frequency rotational speed.

[0021] Further, in step 4), when the rotational speed of the unit reaches the lower boundary of the rotational speed resonance region and remains stable, the absorption power of the current unit is calculated according to the following formula:

[0022]

[0023] The change of rotational kinetic energy of the unit from static to stable at the lower boundary of the rotational speed resonance region is:

[0024]

[0025] The tip speed ratio is defined as:

[0026]

[0027] At this time, the absorption power is converted from the kinetic energy, i.e. formula (2), (3) are equal, and formula (4) is associated:

[0028]

[0029] In the formula, Δt is the time from the unit being static to the rotational speed reaching the lower boundary of the resonance region, β is the current pitch angle of the unit, C p is the wind energy absorption efficiency, β can be measured by a pitch encoder; I is the rotational inertia of the rotating part of the unit, ω is the angular velocity, β, S, R are air density, swept area and impeller radius respectively; all values on the right side of the equation are sensor measurable or inherent parameters of the unit, and the function relationship C p (λ, β) can be obtained in the early simulation, and the tip speed ratio λ can be solved according to the above formula (5);

[0030] The tip speed ratio λ is re-substituted into formula (4) to obtain the estimated equivalent wind speed v of the impeller surface;

[0031] The estimated equivalent wind speed v and the optimal pitch angle β minimum are re-substituted to obtain:

[0032]

[0033] The optimal absorption power of the unit at the estimated equivalent wind speed can be calculated by formula (6).

[0034] Further, in step 5), an additional pitch bias is superimposed in the pitch controller of the unit, which is expressed as:

[0035]

[0036] ω rotorspeed ∈[a*ω coupfre b*ω coupfre ]

[0037] wherein, ε bias is the pitch bias, abs is the absolute value function, ω rotorspeed is the measured rotor speed of the unit, i.e., the unit speed; when the unit speed is in the speed resonance region, the pitch bias increases as the speed approaches the coupling frequency speed, and vice versa, the pitch bias is directly superimposed in the input of the pitch controller, the calculated pitch command is transmitted to the pitch actuator, so that the faster the unit rotor speed approaches the coupling frequency speed point, the faster the pitch is opened.

[0038] The second object of the application is achieved by the following technical scheme: a wind turbine unit pre-grid resonance crossing system for realizing the wind turbine unit pre-grid resonance crossing method described above, comprising:

[0039] A parameter confirmation module is configured to determine the tower natural frequency of the unit and the corresponding coupling frequency speed, and determine the speed resonance region according to the coupling frequency speed point.

[0040] A first judgment module is configured to judge whether the current nacelle wind speed is greater than a set value, if yes, the unit is started normally, and if no, a second judgment module is executed.

[0041] The second judgment module is configured to judge whether the unit has fast crossing capability, at this time, the lower boundary of the speed resonance region is set as a target value, when the unit speed reaches the lower boundary of the speed resonance region and remains stable, the estimated wind speed of the current unit is calculated, and it is judged whether the optimal absorbed power under the estimated wind speed is greater than a preset threshold, if yes, it is considered that the unit has fast crossing capability, and a fast crossing module is executed, if it is judged that the unit does not have fast crossing capability, the lower boundary of the speed resonance region is continuously maintained as the target value, and when the absorbed power is greater than the preset threshold, the crossing is performed.

[0042] The fast crossing module is configured to change the target value to the grid-connected speed, and additionally superimpose the pitch bias in the pitch controller of the unit to make the unit pitch fast to cross the speed, and start timing, if the unit speed is greater than the upper boundary of the speed resonance region within a specified time, the pre-grid resonance crossing is completed, if the unit speed is still in the speed resonance region, i.e., less than the upper boundary of the speed resonance region, within the specified time, the pitch bias is cancelled, the second judgment module and the fast crossing module are repeatedly executed until the unit speed is greater than the upper boundary of the speed resonance region within the specified time, and the pre-grid resonance crossing is completed.

[0043] The third object of the present invention is achieved through the following technical solution: a storage medium stores a program, and when the program is executed by a processor, the above-mentioned resonance ride-through method before the wind turbine generator set is connected to the grid is implemented.

[0044] The fourth purpose of the present invention is achieved through the following technical solution: a computing device, comprising a processor and a memory for storing a program executable by the processor, wherein when the processor executes the program stored in the memory, the above-mentioned resonance ride-through method before the wind turbine is connected to the grid is implemented.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] 1. The present invention can avoid the wind turbine generator set from being affected by frequency rotation and tower resonance before being connected to the grid, thereby increasing the service life of the set.

[0047] 2. The unit grid-connected signal does not only rely on the average wind speed of the anemometer. When the wind speed is lower than the cut-in wind speed, the unit will remain in the grid-connected state at any time. When the grid-connected capacity is reached through inference from the unit's operating status, the unit will be quickly connected to the grid, effectively improving the grid-connected efficiency, reducing the unit failure rate, and increasing the number of power generation hours under low wind speed conditions.

[0048] 3. The present invention is simple to implement and does not require additional sensors and hardware. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Flowchart of the method of the present invention.

[0050] Figure 2 This is the pitch control block diagram.

[0051] Figure 3 This is an architecture diagram of the system of the present invention. DETAILED DESCRIPTION

[0052] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment discloses a resonance ride-through method for a wind turbine generator set before grid connection, and its specific solution is as follows:

[0055] 1) Determine the tower natural frequency of the unit and its corresponding coupling frequency speed;

[0056] The cabin lateral vibration acceleration data of the unit is acquired, the cabin lateral vibration acceleration data is grouped, the Fourier transform is performed on the cabin lateral vibration acceleration data of each group to obtain frequency domain data of each group, and the characteristic frequency between the rated speed one times rotational frequency and the rated speed three times rotational frequency is compared with the modal tower frequency in simulation, and the characteristic frequency with a deviation within a preset range from the modal tower frequency is selected as the tower natural frequency;

[0057] The coupling frequency rotational speed corresponding to the tower natural frequency is calculated according to the following formula:

[0058]

[0059] In the formula, ω coupfre is the coupling frequency rotational speed, f tower is the tower natural frequency.

[0060] 2) The rotational speed resonance region is determined according to the coupling frequency rotational speed point, and the upper boundary and the lower boundary of the rotational speed resonance region are generally in a multiple relationship of the coupling frequency rotational speed, that is, [a*ω coupfre b*ω coupfre ], a < 1, b > 1, wherein ω coupfre is the coupling frequency rotational speed.

[0061] 3) If the current cabin wind speed is greater than 5 m / s, the unit is normally started, and if it is less than 5 m / s, step 4) is performed;

[0062] 4) It is judged whether the unit has a rapid crossing capability, at this time, the lower boundary of the rotational speed resonance region is set as a target value, when the unit rotational speed reaches the lower boundary of the rotational speed resonance region and is stable, the absorption power of the current unit is calculated, and the absorption power of the current unit is calculated according to the following formula:

[0063]

[0064] The rotational kinetic energy change of the unit from static to the lower boundary of the rotational speed resonance region when stable is:

[0065]

[0066] The tip speed ratio is defined as:

[0067]

[0068] At this time, the absorption power is converted from the kinetic energy, that is, formulas (2) and (3) are equal, and formula (4) can be obtained by combining formulas (2) and (3):

[0069]

[0070] In the formula, Δt is the time from the unit from static to the lower boundary of the rotational speed resonance region, β is the current pitch angle of the unit, and Cp For wind energy absorption efficiency, β can be measured by the pitch encoder; I is the rotational inertia of the rotating part of the unit, ω is the angular velocity, ρ, S, R are air density, swept area and impeller radius respectively; all values on the right side of the equation are sensor measurable or inherent parameters of the unit, and the function relationship C p (λ, β) can be obtained in the early simulation, and the tip speed ratio λ can be solved according to the above formula (5);

[0071] The tip speed ratio λ is substituted back into formula (4) to obtain the estimated equivalent wind speed v of the impeller surface;

[0072] The estimated equivalent wind speed v and the optimal pitch angle β minimum are substituted back to obtain:

[0073]

[0074] The absorption power of the unit under the estimated equivalent wind speed can be calculated by formula (6); it is set that when the absorption power of the unit is greater than the preset threshold, it is considered that the unit has the rapid crossing ability, step 5) is executed, if it is judged that the unit does not have the rapid crossing ability, the lower boundary of the resonance region of the speed is kept as the target value, and when the absorption power is greater than the preset threshold, the crossing is performed.

[0075] 5) The target value is changed to the grid-connected speed, an additional pitch bias is superimposed in the pitch controller of the unit to make the unit quickly pitch to cross the speed, and the timing starts, as shown in Figure 2

[0076]

[0077] ω rotorspeed ∈[a*ω coupfre b*ω coupfre ]

[0078] In the formula, ε bias is the pitch bias, abs is the absolute value function, ω rotorspeed is the measured impeller speed of the unit, i.e. the unit speed; when the unit speed is in the speed resonance region, the pitch bias increases as the speed approaches the coupling frequency speed, and vice versa, the pitch bias decreases as the coupling frequency speed increases. The pitch bias is directly superimposed in the input of the pitch controller, the calculated pitch command is transmitted to the pitch actuator, so that the pitch rate is faster when the impeller speed of the unit is closer to the coupling frequency speed point;

[0079] ​If the unit speed is greater than the upper boundary of the speed resonance region within 30 seconds, the resonance crossing before grid connection is completed. If the unit speed is still within the speed resonance region, i.e. less than the upper boundary of the speed resonance region, the pitch bias is cancelled, steps 4) and 5) are repeatedly executed until the unit speed is greater than the upper boundary of the speed resonance region within 30 seconds, and the resonance crossing before grid connection is completed.

[0080] Embodiment 2

[0081] The embodiment discloses a wind turbine unit resonance crossing before grid connection system for implementing the wind turbine unit resonance crossing before grid connection method in embodiment 1, as shown in the following figure, which comprises: Figure 3

[0082] A parameter confirmation module is configured to determine the tower natural frequency of the unit and the corresponding coupling frequency speed, and determine the speed resonance region according to the coupling frequency speed point.

[0083] A first judgment module is configured to judge whether the current nacelle wind speed is greater than a set value. If yes, the unit is started normally. If no, a second judgment module is executed.

[0084] The second judgment module is configured to judge whether the unit has a fast crossing capability. At this time, the lower boundary of the speed resonance region is set as a target value. When the unit speed reaches the lower boundary of the speed resonance region and remains stable, the estimated wind speed of the current unit is calculated, and it is judged whether the optimal absorbed power under the estimated wind speed is greater than a preset threshold. If yes, it is considered that the unit has a fast crossing capability, and a fast crossing module is executed. If it is judged that the unit does not have a fast crossing capability, the lower boundary of the speed resonance region is continuously maintained as the target value, and the crossing is performed when the absorbed power is greater than the preset threshold.

[0085] The fast crossing module is configured to change the target value to a grid connection speed, add a pitch bias to the pitch controller of the unit to make the unit pitch fast to cross the speed, and start timing. If the unit speed is greater than the upper boundary of the speed resonance region within a specified time, the resonance crossing before grid connection is completed. If the unit speed is still within the speed resonance region, i.e. less than the upper boundary of the speed resonance region, the pitch bias is cancelled, the second judgment module and the fast crossing module are repeatedly executed until the unit speed is greater than the upper boundary of the speed resonance region within the specified time, and the resonance crossing before grid connection is completed.

[0086] Embodiment 3

[0087] The embodiment discloses a storage medium storing a program, which is executed by a processor to implement the wind turbine unit resonance crossing before grid connection method in embodiment 1.

[0088] ​The storage medium in the embodiment can be a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), a U disk, a mobile hard disk, and the like.

[0089] Embodiment 4

[0090] The embodiment discloses a computing device, comprising a processor and a memory for storing a processor-executable program, when the processor executes the program stored in the memory, the wind turbine unit pre-grid resonance ride-through method in embodiment 1 is realized.

[0091] The computing device in the embodiment can be a desktop computer, a notebook computer, a smart phone, a PDA handheld terminal, a tablet computer, a programmable logic controller (PLC), or other terminal devices with processor functions.

[0092] The above-mentioned embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above-mentioned embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and all are included in the protection scope of the present application.

Claims

1. A resonance ride-through method for a wind turbine generator set before grid connection, characterized in that: The following steps are involved: 1) Determine the natural frequency of the tower and its corresponding coupling frequency speed of the unit; 2) Determine the speed resonance region based on the coupling frequency speed; 3) If the current cabin wind speed is greater than the set value, start the engine normally; if it is less than, proceed to step 4); 4) Determine whether the unit has the ability to quickly cross over. In this case, set the lower boundary of the speed resonance region as the target value. When the unit speed reaches the lower boundary of the speed resonance region and remains stable, calculate the estimated wind speed of the current unit and determine whether the optimal absorbed power at the estimated wind speed is greater than a preset threshold. If so, the unit is considered to have the ability to quickly cross over, and execute step 5). If it is determined that the unit does not have the ability to quickly cross over, continue to maintain the lower boundary of the speed resonance region as the target value, and cross over when the absorbed power is greater than the preset threshold. 5) The target value is changed to the grid-connected speed. A pitch bias is additionally superimposed on the pitch controller of the unit to enable the unit to quickly change pitch for speed crossing, and timing is started. If the unit speed is greater than the upper boundary of the speed resonance region within the specified time, the pre-grid connection resonance crossing is completed. If the unit speed is still within the speed resonance region, that is, less than the upper boundary of the speed resonance region within the specified time, the pitch bias is canceled, and steps 4) and 5) are repeated until the unit speed is greater than the upper boundary of the speed resonance region within the specified time, and the pre-grid connection resonance crossing is completed.

2. A method for resonance ride-through before grid connection of a wind turbine generator set according to claim 1, characterized in that: In step 1), the coupling frequency speed corresponding to the tower natural frequency is calculated according to the following formula: （1）； Where, is the coupling frequency speed, is the natural frequency of the tower.

3. A resonance ride-through method for a wind turbine generator set before grid connection according to claim 1, characterized in that: In step 2), the upper and lower boundaries of the speed resonance region are both multiples of the coupling frequency speed, that is: ,in is the coupling frequency speed.

4. A resonance ride-through method for a wind turbine generator set before grid connection according to claim 1, characterized in that: In step 4), when the unit speed reaches the lower boundary of the speed resonance region and remains stable, the current unit absorbed power is calculated according to the following formula: （2）； The change in rotational kinetic energy of the unit from static to stable at the lower boundary of the speed resonance region is: （3）； Tip speed ratio definition: （4）； At this time, the absorbed power is converted from kinetic energy, that is, formula (2) and (3) are equal, and formula (4) is combined to obtain: （5）； Where, It is the time from the unit being stationary to the speed reaching the lower boundary of the speed resonance area, is the current pitch angle of the unit, is the wind energy absorption efficiency, Can be measured by pitch encoder; is the moment of inertia of the rotating parts of the unit, is the angular velocity, 、 、 They are air density, swept area and impeller radius respectively; all values ​​on the right side of the equation are measurable by the sensor or inherent parameters of the unit, and the functional relationship It can be obtained in the early simulation, and the tip speed ratio can be solved according to the above formula (5) ; Tip speed ratio Substituting it back into formula (4), the estimated equivalent wind speed on the impeller surface is obtained: ; The estimated equivalent wind speed and optimal pitch angle Resubstituting: （6）； The optimal absorbed power of the unit under the estimated equivalent wind speed can be calculated using formula (6).

5. A resonance ride-through method for a wind turbine generator set before grid connection according to claim 3, characterized in that: In step 5), the pitch bias is additionally added to the pitch controller of the unit, and the formula is expressed as: ； ； Where, is the pitch offset, is the absolute value function, is the impeller speed measured for the unit, that is, the unit speed; when the unit speed is in the speed resonance area, the pitch bias increases as the speed approaches the coupling frequency speed, and conversely decreases when it moves away from the coupling frequency speed. The pitch bias is directly superimposed on the input of the pitch controller, and the calculated pitch command is transmitted to the pitch actuator, so that the closer the unit impeller speed is to the coupling frequency speed point, the faster the pitch opening rate.

6. A resonance ride-through system for wind turbine generators before grid connection, characterized in that: A method for achieving resonance ride-through before grid connection of a wind turbine generator set according to any one of claims 1 to 5, comprising: The parameter confirmation module is used to determine the tower natural frequency of the unit and its corresponding coupling frequency speed, and determine the speed resonance area according to the coupling frequency speed point; The first judgment module is used to judge whether the current cabin wind speed is greater than the set value. If it is greater, the engine is started normally; if it is less, the second judgment module is executed; The second judgment module is used to determine whether the unit has the ability to quickly cross the speed. At this time, the lower boundary of the speed resonance area is set as the target value. When the unit speed reaches the lower boundary of the speed resonance area and remains stable, the estimated wind speed of the current unit is calculated, and it is determined whether the optimal absorbed power at the estimated wind speed is greater than a preset threshold. If it is greater, the unit is considered to have the ability to quickly cross the speed, and the fast crossing module is executed. If it is determined that the unit does not have the ability to quickly cross the speed, the lower boundary of the speed resonance area is continued to be set as the target value, and the crossing is performed when the absorbed power is greater than the preset threshold. The fast crossing module is used to change the target value into the grid-connected speed, and additionally superimpose the pitch bias in the pitch controller of the unit to enable the unit to quickly change the pitch for speed crossing, and start timing. If the unit speed is greater than the upper boundary of the speed resonance area within the specified time, the pre-grid connection resonance crossing is completed. If the unit speed is still within the speed resonance area within the specified time, that is, less than the upper boundary of the speed resonance area, the pitch bias is canceled, and the second judgment module and the fast crossing module are repeatedly executed until the unit speed is greater than the upper boundary of the speed resonance area within the specified time, and the pre-grid connection resonance crossing is completed.

7. A storage medium storing a program, characterized in that: When the program is executed by a processor, the resonance ride-through method before grid connection of a wind turbine generator set according to any one of claims 1 to 5 is implemented.

8. A computing device comprising a processor and a memory for storing a program executable by the processor, characterized in that: When the processor executes the program stored in the memory, the resonance ride-through method before grid connection of a wind turbine generator set according to any one of claims 1 to 5 is implemented.

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