Control method for switching wind facing directions of wind turbine in special terrain

Abstract

The invention discloses a wind facing direction switching control method for a wind turbine in a special terrain. The method comprises the steps that S1, whether the wind turbine meets a switching-out condition or not is judged; s2, the wind turbine actively selects whether the wind direction state faces wind or the downwind direction state faces wind according to the relation between the average incoming wind pitch-up angle and the two critical wind direction angles; s3, the wind turbine is switched from the upwind direction state to the downwind direction state according to the wind conditions and the conditions of the wind turbine; and S4, according to the wind conditions and the conditions of the wind turbine, the wind turbine is switched from the downwind direction state to the upwind direction state. The wind turbine can be matched with different incoming wind pitch-up angles to actively adjust the wind facing state, so that the wind turbine has the advantages of an upwind running state and a downwind running state, the running wind speed interval of the wind turbine is increased, the generating capacity of the wind turbine is improved, meanwhile, the limit load of the wind turbine can be reduced, and the cost per kilowatt hour is reduced.

Description

Technical Field

[0001] The invention relates to the field of wind turbines, and in particular to a method for controlling wind direction switching of a wind turbine on a special terrain. Background Art

[0002] Wind energy is an important component of renewable energy. In order to reduce the cost per kilowatt-hour, the size of wind turbines is constantly developing towards large-scale. In the next five years, the power of commercial wind turbines is expected to reach 20MW, and the diameter of the wind rotor will increase to 300m. The increase in blade length also increases its flexibility. Under the same load conditions, the deformation of the blades is greater. The blades of wind turbines designed for operation in the above wind direction state will deform in the direction close to the tower, creating a significant risk of collision between the blades and the tower. Therefore, the blades of wind turbines designed for operation in the above wind direction state must have sufficient mass to provide sufficient rigidity to avoid collision between the blades and the tower, limiting the possibility of blade weight reduction.

[0003] Wind turbines operating in the headwind state and wind turbines operating in the leeward state have their own advantages and disadvantages. If a wind turbine can have both the headwind and leeward operating states, it may be the design direction of future super-large wind turbines. The invention with application number (202110411563X) discloses a control method for a super-large wind turbine, which includes a headwind-leeward switching control strategy for adjusting the wind turbine from the headwind state to the leeward state. The headwind-leeward switching strategy can switch the wind turbine from the headwind state to the leeward state by controlling the yaw motion and pitch motion of the wind turbine. This allows the wind turbine to operate in the leeward state, increases the gap between the blades and the tower, increases the upper limit of the operating range of the wind turbine, achieves unloading in strong winds, and can use lighter and softer blades, reducing the cost per kilowatt-hour. However, the current prior art does not judge whether to switch a wind turbine operating in the upwind direction to the downwind direction according to the upward angle of the incoming wind, nor does it have a logical relationship between the switching process between the upwind direction and the downwind direction and the incoming wind direction. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for switching the wind direction of a wind turbine in special terrain, so that the wind turbine can actively adjust the wind direction to match different incoming wind inclination angles, so that the wind turbine has the advantages of both upwind and downwind operating states, increase the operating wind speed range of the wind turbine, and improve the power generation of the wind turbine. At the same time, it can also reduce the ultimate load of the wind turbine and reduce the cost per kilowatt-hour.

[0005] The object of the present invention is achieved by: a method for controlling wind direction switching of a wind turbine in a special terrain, comprising the following steps:

[0006] Step S1: Determine whether the wind turbine meets the cut-out condition: if the cut-out condition is met, the wind turbine is cut-out, and then the process returns to step S1; if the cut-out condition is not met, the process proceeds to step S2;

[0007] Step S2: The wind turbine actively selects to face the wind in the upwind state or the downwind state according to the relationship between the average incoming wind upward angle and the two critical wind direction angles;

[0008] Step S3: switching the wind turbine from an upwind state to a downwind state according to the wind conditions and the conditions of the wind turbine itself;

[0009] Step S4: switching the wind turbine from the downwind state to the upwind state according to the wind conditions and the conditions of the wind turbine itself.

[0010] As a further limitation of the present invention, step S2 specifically includes: determining whether the wind turbine is in an upwind state or a downwind state: if the wind turbine is in an upwind state, determining the average wind inflow upward angle A in the time period T1 wind Is it greater than the critical wind direction angle A? set1 , if A is satisfied wind >A set1 Then go to step S3. If A is satisfied wind ≤A set1 Then return to step S2 to continue to determine whether the wind turbine is in the upwind state or the downwind state; if the wind turbine is in the downwind state, determine the average inflow wind upward angle A in the time period T1 wind Is it less than the critical wind direction angle A? set2 , if A is satisfied wind <A set1 Then go to step S4. If A is satisfied wind ≥A set1 Then return to step S2 to continue to determine whether the wind turbine is in the upwind state or the downwind state; the value range of the two critical wind direction angles is 0° set2 ≤A set1 <30°.

[0011] As a further limitation of the present invention, step S3 specifically includes:

[0012] Step S3.1: Determine whether the wind turbine meets the extreme working condition. If the wind turbine meets the extreme working condition, the wind turbine load reduction control is performed. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme working condition is met; if the wind turbine does not meet the extreme working condition, determine whether the load of the key part of the wind turbine exceeds the standard. If the load of the key part of the wind turbine exceeds the standard, the wind turbine load reduction control is performed. If the load of the key part of the wind turbine does not exceed the standard, enter step S3.2;

[0013] ​Step S3.2: Execute the switching of the wind turbine from the upwind state to the downwind state. The wind turbine performs yaw motion and pitch motion, and then determines whether the switching from the upwind state to the downwind state is completed. If the switching from the upwind state to the downwind state is not completed, return to step S3.1; if the switching from the upwind state to the downwind state is completed, the wind turbine is in the downwind state, and then returns to step S1.

[0014] As a further limitation of the present invention, step S4 specifically includes:

[0015] Step S4.1: Determine whether the wind turbine meets the extreme working condition. If the wind turbine meets the extreme working condition, the wind turbine load reduction control is performed. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme working condition is met; if the wind turbine does not meet the extreme working condition, determine whether the load of the key part of the wind turbine exceeds the standard. If the load of the key part of the wind turbine exceeds the standard, the wind turbine load reduction control is performed. If the load of the key part of the wind turbine does not exceed the standard, enter step S4.2;

[0016] Step S4.2: Execute the switching of the wind turbine from the downwind state to the upwind state, the wind turbine performs yaw movement and pitch movement, and then determines whether the switching from the downwind state to the upwind state is completed. If the switching from the downwind state to the upwind state is not completed, return to step S4.1; if the switching from the downwind state to the upwind state is completed, the wind turbine is in the upwind state, and then returns to step S1.

[0017] As a further limitation of the present invention, the confirmation process of the extreme operating conditions described in step S3.1 is: performing aeroelastic dynamics simulation on the wind turbine, the simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China, and the simulated wind turbine moves as the wind turbine switches from an upwind state to a downwind state; if the performance of the wind turbine under certain extreme wind conditions violates the design strength condition or the design stiffness condition or the design aeroelastic stability condition or the resonance limit condition or the design buckling failure limit condition, then the extreme wind condition is included in the extreme operating condition in step S3.1.

[0018] As a further limitation of the present invention, the confirmation process of the extreme operating conditions described in step S4.1 is: performing aeroelastic dynamics simulation on the wind turbine, the simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China, and the simulated wind turbine moves as a wind turbine switching from a downwind state to an upwind state; if the performance of the wind turbine under certain extreme wind conditions violates the design strength condition or the design stiffness condition or the design aeroelastic stability condition or the resonance limit condition or the design buckling failure limit condition, then the extreme wind condition is included in the extreme operating condition in step S4.1.

[0019] As a further limitation of the present invention, the method of determining whether the load at a key part of a wind turbine exceeds the standard specifically includes: installing a sensor at the key part of the wind turbine, and if the displacement measured by the sensor exceeds the standard, or the speed exceeds the standard, or the acceleration exceeds the standard, or the load exceeds the standard, then determining that the measurement value at the key part of the wind turbine exceeds the standard.

[0020] As a further limitation of the present invention, the judgment as to whether the switching from the upwind state to the downwind state is completed in step S3.2 specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the yaw angle of the wind turbine in the upwind working state is A; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the upwind working state is B; the absolute value range of the yaw angle A is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

[0021] As a further limitation of the present invention, the judgment as to whether the switching from the downwind state to the upwind state is completed in step S4.2 specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the downwind state to the upwind state is completed and the yaw angle of the wind turbine in the downwind working state is C; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the downwind working state is D; the absolute value range of the yaw angle C is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

[0022] As a further limitation of the present invention, when the wind turbine is in the upwind state, the rotation direction of the wind rotor relative to the generator housing is opposite to the rotation direction of the wind rotor relative to the generator housing when the wind turbine is in the downwind state; when the wind turbine is in the upwind state, the wind rotor is located on the upwind side of the tower, and the wind first flows through the wind rotor and then flows to the tower; when the wind turbine is operating in the downwind state, the wind rotor is located on the downwind side of the tower, and the wind first flows through the tower and then flows to the wind rotor.

[0023] The present invention adopts the above technical scheme, and compared with the prior art, the beneficial effects are as follows: the present invention can enable the wind turbine to realize active switching between the downwind state and the upwind state according to the incoming wind direction, and the wind turbine switches from the upwind state to the downwind state under the condition of large incoming wind upward angle; the wind turbine switches from the downwind state to the upwind state under the condition of small incoming wind upward angle; and the wind turbine load reduction control can be turned on for extreme wind conditions; the present invention can enable the wind turbine to actively adjust according to the wind direction conditions, so that the wind turbine has the advantages of both the upwind operating state and the downwind operating state, thereby increasing the operating wind speed range of the wind turbine, and improving the power generation of the wind turbine. At the same time, it can also reduce the ultimate load of the wind turbine and reduce the cost per kilowatt-hour. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a logical schematic diagram of the present invention.

[0025] Figure 2 Schematic diagram of a wind turbine in a downwind position on a special terrain.

[0026] Figure 3 This is a power comparison diagram of a 5MW wind turbine in the downwind state and the upwind state when the incoming wind is upward.

[0027] Figure 4 This is a comparison diagram of the equivalent fatigue of the blade root bending moment of a 5MW wind turbine in the downwind state and the upwind state when the incoming wind is upward. DETAILED DESCRIPTION

[0028] like Figure 1 A method for controlling wind direction switching of a wind turbine in a special terrain is shown, comprising the following steps:

[0029] Step S1: Determine whether the wind turbine meets the cut-out condition. If the cut-out condition is met, the wind turbine is cut out, and then the process returns to step S1 to continue to determine whether the wind turbine meets the cut-out condition; if the cut-out condition is not met, the process proceeds to step S2;

[0030] Step S2: The wind turbine actively selects to face the wind in the upwind state or the downwind state according to the relationship between the average incoming wind upward angle and the two critical wind direction angles;

[0031] Determine whether the wind turbine is in the upwind state or the downwind state: If the wind turbine is in the upwind state, determine the average wind inflow upward angle A in the time period T1 wind Is it greater than the critical wind direction angle A? set1 , if A is satisfied wind >A set1 Then go to step S3. If A is satisfied wind ≤A set1Then return to step S2 to continue judging whether the wind turbine is in the upwind state or the downwind state; if the wind turbine is in the downwind state, judge the average upwind angle A of the oncoming wind during the time period T1 wind Whether it is less than the critical wind direction angle A set2 , if A wind <A set1 is satisfied, then enter step S4; if A wind ≥A set1 is satisfied, then return to step S2 to continue judging whether the wind turbine is in the upwind state or the downwind state; the value range of the two critical wind direction angles is 0°<A set2 ≤A set1 <30°;

[0032] The upwind angle A of the oncoming wind wind refers to the angle between the oncoming wind velocity vector and the normal of the wind turbine plane; the wind turbine that activates the wind direction switching control method for special terrain wind turbines actively selects whether to face the wind in the upwind state or the downwind state according to the relationship between the average upwind angle of the oncoming wind and the two critical wind direction angles; since the projected area of the wind turbine perpendicular to the oncoming wind decreases approximately proportionally to the cosine function cos(A wind ) as the upwind angle of the oncoming wind increases, when A wind =30°, cos(A wind )≈0.866, representing a power loss of about 13.4%. Therefore, the value range of the two critical wind direction angles is 30>A set1 ≥A set2 >0; if it is set that A set1 >A set2 , then when the average upwind angle A wind rapidly decreases after step S3 is executed, the time for the wind turbine to enter step S4 is postponed, so that the wind turbine will enter step S4 only when the average upwind angle A wind drops to a smaller A set2 ; it also makes the time for the wind turbine to enter step S3 postponed when the average upwind angle A wind rapidly increases after step S4 is executed, so that the wind turbine will enter step S4 only when the average upwind angle A wind increases to a larger A set1 ; if it is set that A set1 =A set2 , then the wind turbine uses the same wind direction angle value to judge whether to switch between the upwind state and the downwind state; the range of the time period T1 is 10 seconds < T1 < 60 minutes.

[0033] Step S3: According to the wind conditions and the conditions of the wind turbine itself, perform the switching of the wind turbine from the upwind state to the downwind state;

[0034] Step S3.1: Determine whether the wind turbine meets the extreme operating conditions. If the wind turbine meets the extreme operating conditions, perform load reduction control on the wind turbine. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme operating conditions are met; if the wind turbine does not meet the extreme operating conditions, determine whether the load of the key parts of the wind turbine exceeds the standard, install sensors at the key parts of the wind turbine, and if the displacement measured by the sensor exceeds the standard, the speed exceeds the standard, the acceleration exceeds the standard, or the load exceeds the standard, it is determined that the measurement value of the key part of the wind turbine exceeds the standard; if the load of the key part of the wind turbine exceeds the standard, perform load reduction control on the wind turbine, and if the load of the key part of the wind turbine does not exceed the standard, enter step S3.2; after the wind turbine load reduction control is performed, the wind turbine performs pitch change, braking, shutdown, and yaw actions to reduce the load of the wind turbine;

[0035] The confirmation process of extreme operating conditions is as follows: aeroelastic dynamics simulation is performed on the wind turbine that is to adopt the wind direction switching control method of the special terrain wind turbine. The simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China. The simulated wind turbine moves as the wind turbine switches from the upwind state to the downwind state; if the performance of the wind turbine under certain extreme wind conditions violates the design strength condition or the design stiffness condition or the design aeroelastic stability condition or the resonance limit condition or the design buckling failure limit condition, then the extreme wind condition is included in the extreme operating condition in step S3.1.

[0036] Step S3.2: Execute the switching of the wind turbine from the upwind state to the downwind state, the wind turbine performs yaw motion and pitch motion, and then determines whether the switching from the upwind state to the downwind state is completed. If the switching from the upwind state to the downwind state is not completed, return to step S3.1; if the switching from the upwind state to the downwind state is completed, the wind turbine is in the downwind state, and then return to step S1; Figure 2 Shown is a wind turbine in a downwind position on a special terrain.

[0037] Determining whether the switching from the upwind state to the downwind state is completed specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the yaw angle of the wind turbine in the upwind working state is A; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the upwind working state is B; the absolute value range of the yaw angle A is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

[0038] Step S4: switching the wind turbine from a downwind state to an upwind state according to the wind conditions and the conditions of the wind turbine itself;

[0039] Step S4.1: Determine whether the wind turbine meets the extreme operating conditions. If the wind turbine meets the extreme operating conditions, perform load reduction control on the wind turbine. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme operating conditions are met; if the wind turbine does not meet the extreme operating conditions, determine whether the load of the key parts of the wind turbine exceeds the standard, install sensors at the key parts of the wind turbine, and if the displacement measured by the sensor exceeds the standard, or the speed exceeds the standard, or the acceleration exceeds the standard, or the load exceeds the standard, it is determined that the measurement value of the key part of the wind turbine exceeds the standard; if the load of the key part of the wind turbine exceeds the standard, perform load reduction control on the wind turbine, and if the load of the key part of the wind turbine does not exceed the standard, enter step S4.2; after the wind turbine load reduction control is performed, the wind turbine performs pitch change, braking, shutdown, and yaw actions to reduce the load of the wind turbine;

[0040] The confirmation process of the extreme working condition is as follows: aeroelastic dynamics simulation is performed on the wind turbine that is to adopt the wind direction switching control method of the special terrain wind turbine, the simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China, and the simulated wind turbine moves as the wind turbine switches from the downwind state to the upwind state; if the performance of the wind turbine violates the design strength condition or the design stiffness condition or the design aeroelastic stability condition or the resonance limit condition or the design buckling failure limit condition under a certain extreme wind condition, then the extreme wind condition is included in the extreme working condition in step S4.1;

[0041] Step S4.2: Execute the switching of the wind turbine from the downwind state to the upwind state, the wind turbine performs yaw movement and pitch movement, and then determines whether the switching from the downwind state to the upwind state is completed. If the switching from the downwind state to the upwind state is not completed, return to step S4.1; if the switching from the downwind state to the upwind state is completed, the wind turbine is in the upwind state, and then returns to step S1.

[0042] Determining whether the switching from the downwind state to the upwind state is completed specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the downwind state to the upwind state is completed and the yaw angle of the wind turbine in the downwind working state is C; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the downwind working state is D; the absolute value range of the yaw angle C is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

[0043] When the wind turbine is in the upwind state, the rotation direction of the wind rotor relative to the generator housing is opposite to the rotation direction of the wind rotor relative to the generator housing when the wind turbine is in the downwind state; when the wind turbine is in the upwind state, the wind rotor is located on the upwind side of the tower, and the wind first flows through the wind rotor and then flows to the tower; when the wind turbine is operating in the downwind state, the wind rotor is located on the downwind side of the tower, and the wind first flows through the tower and then flows to the wind rotor; the tower adopts a fixed tower or a floating tower.

[0044] like Figure 3 As shown in the figure, the power comparison of a 5MW wind turbine in the downwind state and the upwind state when the incoming wind is upward. It can be seen that when the incoming wind is upward, the wind turbine in the upwind state or running against the wind has a large power loss, while the wind turbine in the downwind state or running away from the wind can maintain a high power level.

[0045] like Figure 4 The figure shows the comparison of equivalent fatigue of the blade root bending moment of a 5MW wind turbine in the downwind state and the upwind state when the incoming wind is upward. TwrBsMxt and TwrBsMMyt are the equivalent fatigue of the bending moment in the swing direction and the equivalent fatigue of the bending moment in the swing direction respectively. It can be seen that the blade root fatigue of the wind turbine in the downwind state or leeward operation is not significantly increased due to the tower wake. Figure 3 and Figure 4 It can be seen that the advantage of operating in the downwind state is when the incoming wind is upward.

[0046] The present invention discloses a method for controlling the wind direction switching of a wind turbine in a special terrain, including: when the special terrain causes a large upward inclination angle of the incoming wind, the wind turbine switches from the upwind direction to the downwind direction; when the incoming wind upward inclination angle is small, the wind turbine switches from the downwind direction to the upwind direction; and the wind turbine load reduction control can be turned on for extreme wind conditions. The present invention can enable the wind turbine to actively adjust the wind direction to match different upward inclination angles of the incoming wind, so that the wind turbine has the advantages of both the upwind direction operating state and the downwind direction operating state, increases the operating wind speed range of the wind turbine, improves the power generation of the wind turbine, and can also reduce the ultimate load of the wind turbine, reducing the cost per kilowatt-hour.

[0047] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A method for controlling wind direction switching of a wind turbine in a special terrain, characterized in that: The following steps are involved: Step S1: Determine whether the wind turbine meets the cut-out condition: if the cut-out condition is met, the wind turbine is cut-out, and then returns to step S1; If the cut-out condition is not met, go to step S2; Step S2: The wind turbine actively selects to face the wind in the upwind state or the downwind state according to the relationship between the average incoming wind upward angle and the two critical wind direction angles; Step S3: switching the wind turbine from an upwind state to a downwind state according to the wind conditions and the conditions of the wind turbine itself; Step S4: switching the wind turbine from the downwind state to the upwind state according to the wind conditions and the conditions of the wind turbine itself.

2. According to claim 1, a method for controlling wind direction switching of a wind turbine in a special terrain is characterized in that: The step S2 specifically includes: determining whether the wind turbine is in an upwind state or a downwind state; if the wind turbine is in an upwind state, determining the average wind inflow upward angle A in the time period T1; wind Is it greater than the critical wind direction angle A? set1 , if A is satisfied wind >A set1 Then go to step S3. If A is satisfied wind ≤A set1 Then return to step S2 to continue to determine whether the wind turbine is in the upwind state or the downwind state; if the wind turbine is in the downwind state, determine the average inflow wind upward angle A in the time period T1 wind Is it less than the critical wind direction angle A? set2 , if A is satisfied wind <A set1 Then go to step S4. If A is satisfied wind ≥A set1 Then return to step S2 to continue to determine whether the wind turbine is in the upwind state or the downwind state; the value range of the two critical wind direction angles is 0° set2 ≤A set1 <30°.​ 3. The method for controlling wind direction switching of a wind turbine in a special terrain according to claim 1 is characterized in that: The step S3 specifically includes: Step S3.1: Determine whether the wind turbine meets the extreme working condition. If the wind turbine meets the extreme working condition, the wind turbine load reduction control is performed. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme working condition is met; if the wind turbine does not meet the extreme working condition, determine whether the load of the key part of the wind turbine exceeds the standard. If the load of the key part of the wind turbine exceeds the standard, the wind turbine load reduction control is performed. If the load of the key part of the wind turbine does not exceed the standard, enter step S3.2; Step S3.2: Execute the switching of the wind turbine from the upwind state to the downwind state. The wind turbine performs yaw motion and pitch motion, and then determines whether the switching from the upwind state to the downwind state is completed. If the switching from the upwind state to the downwind state is not completed, return to step S3.1; if the switching from the upwind state to the downwind state is completed, the wind turbine is in the downwind state, and then returns to step S1.

4. A method for controlling wind direction switching of a wind turbine in a special terrain according to claim 1, characterized in that: The step S4 specifically includes: Step S4.1: Determine whether the wind turbine meets the extreme working condition. If the wind turbine meets the extreme working condition, the wind turbine load reduction control is performed. After the load reduction control is completed, return to step S3.1 to continue to determine whether the extreme working condition is met; if the wind turbine does not meet the extreme working condition, determine whether the load of the key part of the wind turbine exceeds the standard. If the load of the key part of the wind turbine exceeds the standard, the wind turbine load reduction control is performed. If the load of the key part of the wind turbine does not exceed the standard, enter step S4.2; Step S4.2: Execute the switching of the wind turbine from the downwind state to the upwind state, the wind turbine performs yaw movement and pitch movement, and then determines whether the switching from the downwind state to the upwind state is completed. If the switching from the downwind state to the upwind state is not completed, return to step S4.1; if the switching from the downwind state to the upwind state is completed, the wind turbine is in the upwind state, and then returns to step S1.

5. A method for controlling wind direction switching of a wind turbine in a special terrain according to claim 3, characterized in that: The confirmation process of the extreme operating conditions described in step S3.1 is: performing aeroelastic dynamics simulation on the wind turbine, the simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China, and the simulated wind turbine moves as the wind turbine switches from the upwind state to the downwind state; if the performance of the wind turbine under certain extreme wind conditions violates the design strength condition or the design stiffness condition or the design aeroelastic stability condition or the resonance limit condition or the design buckling failure limit condition, then the extreme wind condition is included in the extreme operating conditions in step S3.

1.

6. A method for controlling wind direction switching of a wind turbine in a special terrain according to claim 4, characterized in that: The confirmation process of the extreme working condition described in step S4.1 is: performing aeroelastic dynamics simulation on the wind turbine, the simulated wind conditions include the extreme wind conditions specified in the wind turbine generator set standard issued by the International Electrotechnical Commission IEC and the extreme wind conditions specified in the wind turbine generator set standard issued by the People's Republic of China, and the simulated wind turbine moves as the wind turbine switching from the downwind state to the upwind state; If the performance of the wind turbine under certain extreme wind conditions violates the design strength condition, the design stiffness condition, the design aeroelastic stability condition, the resonance limit condition, or the design buckling failure limit condition, then the extreme wind condition is included in the extreme operating condition in step S4.

1.

7. A method for controlling wind direction switching of a wind turbine in a special terrain according to claim 3 or 4, characterized in that: Determining whether the load at a key part of a wind turbine exceeds the standard specifically includes: installing a sensor at the key part of the wind turbine, and if the displacement measured by the sensor exceeds the standard, or the speed exceeds the standard, or the acceleration exceeds the standard, or the load exceeds the standard, then determining that the measurement value at the key part of the wind turbine exceeds the standard.

8. The method for controlling wind direction switching of a wind turbine in a special terrain according to claim 3 is characterized in that: The judgment as to whether the switching from the upwind state to the downwind state is completed in step S3.2 specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the yaw angle of the wind turbine in the upwind working state is A; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the upwind working state is B; the absolute value range of the yaw angle A is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

9. A method for controlling wind direction switching of a wind turbine in a special terrain according to claim 4, characterized in that: The judgment as to whether the switching from the downwind state to the upwind state is completed in step S4.2 specifically includes: if the difference between the yaw angle of the wind turbine after the switching from the downwind state to the upwind state is completed and the yaw angle of the wind turbine in the downwind working state is C; the difference between the pitch angle of the wind turbine after the switching from the upwind state to the downwind state is completed and the pitch angle of the wind turbine in the downwind working state is D; the absolute value range of the yaw angle C is 140° to 220°, and the absolute value range of the pitch angle B is 140° to 220°.

10. A method for controlling wind direction switching of a wind turbine in a special terrain according to any one of claims 1 to 9, characterized in that: When the wind turbine is in the upwind state, the rotation direction of the wind rotor relative to the generator housing is opposite to the rotation direction of the wind rotor relative to the generator housing when the wind turbine is in the downwind state; when the wind turbine is in the upwind state, the wind rotor is located on the upwind side of the tower, and the wind first flows through the wind rotor and then flows to the tower; when the wind turbine is operating in the downwind state, the wind rotor is located on the downwind side of the tower, and the wind first flows through the tower and then flows to the wind rotor.

Images