Anti-lightning protection method and system for wind turbine generator

Abstract

The invention provides an anti-lightning protection method and system for a wind turbine generator. The method comprises the steps that S1, an electric field sensor is used for monitoring the intensity of an environment electric field; s2, when the environment electric field intensity exceeds a first-level early warning threshold value, a loop resistance detection unit is started, and ground resistance values of lightning protection channels of three blades of the wind turbine generator set are detected respectively; s3, classifying the three blades according to the resistance to ground values, and screening out a preferable lightning receiving blade; s4, continuously monitoring the environment electric field intensity, and executing a shutdown lightning protection strategy when the environment electric field intensity exceeds a second-level action threshold value; and S5, in the shutdown lightning protection strategy, a yaw system and a variable pitch system of the wind turbine generator are controlled, the screened optimal lightning receiving blade is locked at a vertically upward position to serve as a target lightning receiving blade, and an auxiliary grounding device installed between the main shaft and the tower drum is closed. According to the method, the blade in the optimal state can be selected as the lightning arrester through self-inspection, and the posture of the unit is adjusted to achieve optimal drainage.

Description

Technical Field

[0001] This invention relates to the field of wind turbine protection, and in particular to a method and system for protecting wind turbines from lightning strikes. Background Technology

[0002] Currently, common lightning protection for wind turbines mainly relies on passive solutions (such as lightning rods at the blade tips, down conductors, and grounding grids) or simple storm modes (shutting down and feathering upon detecting a thunderstorm). Existing technologies often overlook the differences in lightning protection performance among the three blades. As operating time increases, down conductors on different blades may break or experience increased impedance. If a random shutdown occurs, and the abnormal blade happens to be at its highest point (the lightning strike point), it can easily lead to blade breakage. Furthermore, existing active lightning protection systems often involve complex plasma generators or laser-induced lightning, which are costly and require extensive mathematical model control. Summary of the Invention

[0003] This invention provides a method and system for lightning protection of wind turbine units, which addresses the shortcomings of existing technologies by enabling the selection of the optimal blade as a lightning arrester through self-testing and adjusting the unit's attitude to achieve optimal current diversion.

[0004] This invention provides a method for lightning protection of wind turbine generators, comprising: Step S1: Monitor the ambient electric field strength using an electric field sensor installed on the top of the cabin; Step S2: When the ambient electric field strength exceeds the first-level warning threshold, the loop resistance detection unit is activated to detect the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. Step S3: Classify the three blades according to the ground resistance value and select the preferred lightning protection blade; Step S4: Continue to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, execute the shutdown and lightning protection strategy. Step S5: In the shutdown lightning protection strategy, control the yaw system and pitch system of the wind turbine to lock the selected preferred lightning protection blades in a vertically upward position as the target lightning protection blades, and close the auxiliary grounding device installed between the main shaft and the tower.

[0005] According to the wind turbine lightning protection method provided by the present invention, step S3 specifically includes: Set the standard safety resistance threshold and the ultimate withstand resistance threshold; If the ground resistance value of a certain blade is less than the standard safety resistance threshold, the blade is marked as a preferred lightning protection blade. If the ground resistance value of a blade is greater than or equal to the standard safety resistance threshold and less than the ultimate withstand resistance threshold, the blade is marked as a spare lightning protection blade. If the ground resistance value of a blade is greater than or equal to the ultimate withstand resistance threshold, the blade is marked as a faulty blade.

[0006] According to the lightning protection method for wind turbine generators provided by the present invention, the selection of the target lightning-absorbing blade in step S5 specifically includes: From the list of preferred lightning protection blades, select the blade with the lowest ground resistance value as the target lightning protection blade; If no preferred lightning protection blade is available, the blade with the lowest ground resistance value is selected from the list of blades marked as spare lightning protection blades as the target lightning protection blade.

[0007] According to the wind turbine lightning protection method provided by the present invention, in step S1, four electric field sensors are set and installed in the front, rear, left and right positions on the top of the nacelle respectively. The control of the yaw system in step S5 specifically includes: By comparing the values ​​from the four electric field sensors, the location of the strongest electric field intensity can be determined. If the direction of the strongest electric field is not directly in front of the nacelle, the yaw motor is activated until the front of the nacelle is aligned with the direction of the strongest electric field.

[0008] According to the lightning protection method for wind turbine generators provided by the present invention, step S5, which involves locking the preferred lightning-absorbing blade in a vertically upward position, specifically includes: Control the wind turbine to rotate until the target lightning rod is at the 12 o'clock position; Detect the wind turbine locking angle error. If the error is within the preset range, engage the mechanical brake disc to lock the main shaft.

[0009] According to the wind turbine lightning protection method provided by the present invention, step S5 of controlling the pitch system specifically includes: Adjust the pitch angle of the target flash blade at the 12 o'clock position to 0 degrees fully open. Adjust the pitch angle of the other two blades to 90 degrees in a feathering state.

[0010] According to the wind turbine lightning protection method provided by the present invention, the auxiliary grounding device is a mechanical contact carbon brush or a switch, and closing the auxiliary grounding device in step S5 specifically includes: While the main spindle is mechanically braked and locked, the auxiliary grounding device is activated to allow direct connection between the main spindle and the tower through physical contact points, thereby bypassing the main spindle bearing.

[0011] According to the lightning protection method for wind turbine generators provided by the present invention, step S5 is followed by a post-lightning strike self-test step: After the lightning strike event is detected to have ended and the ambient electric field strength has decreased, the loop resistance detection unit is restarted to detect the ground resistance value of the target lightning arresting blade. The ground resistance value after a lightning strike is compared with the ultimate withstand resistance threshold. If it is greater than the ultimate withstand resistance threshold, the blade is marked as a faulty blade.

[0012] The wind turbine lightning protection method provided by the present invention further includes: If the ambient electric field strength exceeds the first-level warning threshold but does not exceed the second-level action threshold, the unit continues to generate electricity and the resistance detection in step S2 is repeated according to the first preset time interval.

[0013] The present invention also provides a wind turbine lightning protection system, comprising: The monitoring module is installed on the top of the cabin to monitor the intensity of the ambient electric field. The detection module activates the loop resistance detection unit when the ambient electric field strength exceeds the first-level warning threshold, and detects the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. The classification module classifies the three blades according to the ground resistance value and selects the preferred lightning-catching blades. The judgment module continues to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, the shutdown and lightning protection strategy is executed. The execution module, in the shutdown lightning protection strategy, controls the yaw system and pitch system of the wind turbine, locks the selected preferred lightning-absorbing blades in a vertically upward position as the target lightning-absorbing blades, and closes the auxiliary grounding device installed between the main shaft and the tower.

[0014] The wind turbine lightning protection method and system provided by this invention differ from existing technologies that involve random shutdowns. This invention ensures that lightning strikes always occur on the blades with the lowest grounding resistance and the healthiest blades, greatly reducing the risk of blade breakage due to down conductor fracture. Furthermore, it incorporates resistance grading and fault degradation processing logic, finding a suboptimal solution even in the event of partial component failure, rather than blindly operating. It also strongly correlates attitude locking with the closed-loop logic of the auxiliary grounding device, solving the problem of poor contact of the grounding carbon brushes during traditional rotation. Moreover, the entire process of this invention involves only comparisons and logical judgments, resulting in a fast controller response and higher reliability than systems relying on AI prediction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a flowchart illustrating the lightning protection method for wind turbine generators provided by the present invention.

[0017] Figure 2 This is a schematic diagram of the structure of the wind turbine lightning protection system provided by the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] The following is combined with Figures 1 to 3 This invention describes embodiments of the wind turbine lightning protection method and system. It should be understood that the following descriptions are merely illustrative embodiments of the invention and do not constitute any specific limitation on the invention.

[0021] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for lightning protection of wind turbine generators, the method comprising: Step S1: Monitor the ambient electric field strength using an electric field sensor installed on the top of the cabin; Step S2: When the ambient electric field strength exceeds the first-level warning threshold, the loop resistance detection unit is activated to detect the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. Step S3: Classify the three blades according to the ground resistance value and select the preferred lightning protection blade; Step S4: Continue to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, execute the shutdown and lightning protection strategy. Step S5: In the shutdown lightning protection strategy, control the yaw system and pitch system of the wind turbine to lock the selected preferred lightning protection blades in a vertically upward position as the target lightning protection blades, and close the auxiliary grounding device installed between the main shaft and the tower.

[0022] As can be seen from the above embodiments, the wind turbine lightning protection method provided by this invention differs from the random shutdown technology of the prior art. This invention ensures that lightning strikes always occur on the blades with the lowest grounding resistance and the healthiest blades, greatly reducing the risk of blade breakage due to down conductor fracture. Furthermore, it incorporates resistance grading and fault degradation processing logic, which can find a suboptimal solution even in the event of partial component failure, rather than blindly operating. It also strongly correlates attitude locking with the closed-loop logic of the auxiliary grounding device, solving the problem of poor contact of the grounding carbon brushes in traditional rotating states. Moreover, the entire process of this invention involves only comparison and logical judgment, resulting in a fast controller response and higher reliability than systems relying on AI prediction.

[0023] The above method will be described in detail below with reference to embodiments. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute any limitation on the present invention.

[0024] The invention begins with step S1, which involves monitoring the ambient electric field strength using electric field sensors installed on the top of the nacelle. Specifically, in this embodiment, the wind turbine does not rely on a single sensor but employs an array-based monitoring system. Specifically, high-sensitivity atmospheric electric field sensors are installed on the exterior of the nacelle top (within the lightning protection zone) at four positions: front, rear, left, and right. These four sensors correspond to the 0° (front), 90° (right), 180° (rear), and 270° (left) directions in the nacelle coordinate system, respectively. The wind turbine's main controller reads the electric field strength values ​​from these four sensors in real time according to a preset sampling frequency (e.g., once per second), labeling them as Efront, Erear, Eleft, and Eright, respectively.

[0025] By placing sensors in four positions on the top of the cabin—front, rear, left, and right—this step not only detects the possibility of a lightning strike but also implies the direction from which the lightning strike originated through the differences in the four values. Although step S1 is mainly used to trigger an early warning, the real-time data collected in these four positions is a necessary prerequisite for subsequent cabin yaw and protection of the cabin sidewalls.

[0026] Next, the invention proceeds to step S2, whereby when the ambient electric field strength exceeds the first-level warning threshold, the loop resistance detection unit is activated to detect the ground resistance values ​​of the lightning protection channels of the three wind turbine blades. Specifically, the system pre-sets a first-level warning threshold E1 (e.g., 2kV / m, a value set according to the lightning warning standard defined by the local meteorological bureau). Then, the controller executes the following logical judgment steps.

[0027] First, at each sampling time, the controller compares the real-time values ​​from the four sensors and selects the maximum value, denoted as Emax. Then, a threshold comparison process is performed: Scenario 1 (Safe State): If Emax is less than the preset first-level warning threshold E1, the system determines that the current weather is non-thunderstorm or the thunderstorm is far away. At this time, the wind turbine maintains its current normal grid-connected power generation mode without any intervention. To save system resources, the system will wait for a preset time interval T1 (e.g., 60 seconds) and then repeat the above data collection and comparison process.

[0028] Scenario 2 (Warning Triggered): If Emax is greater than or equal to the preset first-level warning threshold E1 and less than the preset second-level action threshold E2, the system determines that the atmospheric electric field around the unit has distorted and a thunderstorm weather is forming or approaching. At this time, the system immediately triggers the next stage of the lightning protection program, that is, automatically jumps to execute the start-up loop resistance detection unit to detect the ground resistance values of the lightning protection channels of the three blades of the wind turbine respectively.

[0029] Compared with the prior art, in the prior art, many units immediately shut down as soon as they detect a thunderstorm signal. By setting the first-level warning threshold E1 in this step, the weather warning and the shutdown action are decoupled. When only exceeding E1 but not reaching the dangerous level, the unit only enters the preparation state (checking the resistance) instead of shutting down immediately. This means that in the marginal or weak thunderstorm weather, the unit can still continue to generate electricity, effectively reducing the power generation loss caused by excessive defense. Moreover, through the judgment condition of Emax≥E1, as the trigger signal for starting the subsequent resistance detection, it ensures that the downlead resistance is only detected when the lightning strike risk truly exists, avoiding the aging of the detection circuit and energy waste caused by frequent detection on weekdays, and also ensuring that the system has completed the physical examination of the blade health status before the lightning strike really comes, eliminating the lag risk.

[0030] Further, when the controller receives the signal fed back by the electric field sensor and confirms that Emax≥E1 and Emax<E2 (the second-level action threshold), it immediately sends an activation instruction to the loop resistance detection unit. The loop resistance detection unit independently detects the three blades (blade A, blade B, blade C) of the wind turbine through the pre-buried measurement lines. The detection loop covers the complete current discharge channel from the tip lightning arrester of the blade, the internal downlead of the blade, the root connection part to the main grounding grid. The system reads the DC resistance values of the three channels in real time, denoted as Ra, Rb, and Rc respectively. To avoid instantaneous interference, the system continuously collects multiple times (e.g., 5 times) within a very short time (e.g., 1 second) and takes the average value as the current final measured resistance value.

[0031] Next, the present invention proceeds to step S3, that is, classifying the three blades according to the ground resistance values and screening out the preferred lightning-receiving blades. Specifically, the core of step S3 is to convert the physically measured resistance values into logical tags recognizable by the control system, so as to decide which blade is the most preferred for lightning reception.

[0032] Specifically, the system presets two key physical thresholds: 1. Standard safety resistance threshold (Rsafe): For example, it is set to 0.2 ohms. This value represents that the down-lead connection of the blade is intact, without corrosion or looseness, and is in the best state at the factory level.

[0033] 2. Limit tolerance resistance threshold (Rlimit): For example, it is set to 1.0 ohms. This value represents that there may be slight oxidation in the down-lead or an increase in the contact resistance at the connection point, but it can still barely discharge the lightning current during an emergency without immediate fusing.

[0034] Then the controller compares Ra, Rb, and Rc obtained in step S2 with the above thresholds respectively.

[0035] If the resistance value Rx of a certain blade < Rsafe, it means that the channel is extremely unobstructed, and the system marks this blade as the preferred lightning-receiving blade. If Rsafe ≤ Rx < Rlimit, it means that the performance of the channel has decreased but has not completely failed, and the system marks this blade as the backup lightning-receiving blade. If Rx ≥ Rlimit, it means that the impedance of the channel is too large (there may be an open circuit or severe corrosion), and it is extremely easy to generate high heat during lightning strikes, causing the blade to burst, and the system marks this blade as a faulty blade (not available).

[0036] Based on the above classification labels, the system executes the final screening logic: Preferred logic: Check if there are blades marked as preferred lightning-receiving blades. If there are (quantity ≥ 1), then directly select the one with the smallest resistance value from these preferred blades as the target lightning-receiving blade.

[0037] Sub-optimal degradation logic: If all blades do not meet the preferred standard (quantity = 0), but there are backup lightning-receiving blades. Then select the one with the smallest resistance value from the backup blades as the target lightning-receiving blade, and at the same time send a maintenance alarm for the lightning protection system to degrade operation to the SCADA system. If all three blades are marked as faulty blades, it is determined that no blade of the unit has the ability to receive lightning strikes, and the full-fault protection mode is triggered.

[0038] Compared to existing technologies, this invention, through the resistance self-testing and classification steps described above, can accurately identify blades with broken down conductors or excessively high impedance, and exclude them from the lightning strike list. This ensures that the blade ultimately used as a lightning rod (the target lightning strike blade) is the one with the best conductivity in the current unit, thus avoiding Joule heating caused by lightning current flowing through a high-impedance path, which could lead to blade cracking or fire. Furthermore, by setting dual thresholds Rsafe and Rlimit, not only is path optimization during lightning strikes achieved, but the system is also effectively given the ability for online health diagnosis. When the system can only select a backup lightning strike blade, although lightning protection can still be provided, a maintenance alarm has already been issued. This tiered strategy ensures that the unit will not be shut down and scrapped due to slight aging, and also avoids blindly connecting to lightning strikes in cases of complete failure. Furthermore, this invention performs the above steps at the first-level warning (E1) stage, rather than waiting until the second-level action (E2), i.e., the moment a lightning strike is about to occur. This means that when a thunderstorm actually arrives and shutdown is required, the system has already locked onto the target blade in advance, eliminating the need for further resistance testing and calculation, and can directly execute mechanical actions. This preprocessing logic greatly shortens the time difference between lightning strike determination and attitude locking, effectively responding to the sudden changes in lightning weather.

[0039] Further, the method of the present invention proceeds to step S4, which involves continuing to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, a shutdown lightning protection strategy is executed. Specifically, in this embodiment of the invention, when the system determines that the ambient electric field strength exceeds the secondary action threshold (E2), it means that a lightning strike is about to occur, and the system immediately switches from monitoring mode to active defense mode. At this time, the controller will execute the optimal attitude locking process according to the corresponding logical sequence.

[0040] In step S4, after the system is in a first-level warning state (i.e., the ambient electric field strength E≥E1) and has completed the blade resistance self-check, the control system enters a highly alert real-time monitoring mode. At this time, the system reads the real-time values ​​of the four azimuth electric field sensors on the top of the nacelle at a higher sampling frequency (e.g., 10 times per second) and compares the maximum value Emax among the four values ​​with the preset second-level action threshold E2. The value of E2 is usually set as the critical field strength when a lightning leader is about to form (e.g., 20kV / m). Only when Emax≥E2 does the system determine that the lightning strike risk is imminent. At this time, regardless of power generation benefits, it immediately issues the highest priority lightning protection shutdown command, forcibly interrupts the current power control cycle, and enters the execution process of step S5. In this way, by setting dual thresholds (E1 warning, E2 action), frequent shutdowns are avoided when thunderstorms do not form due to passing clouds, ensuring the utilization rate of the unit; at the same time, it ensures that there is a sufficient time window before a lightning strike actually occurs (usually, thunderstorm clouds need time to accumulate charge) to complete attitude adjustment.

[0041] As described in step S5, in the shutdown lightning protection strategy, the yaw system and pitch system of the wind turbine are controlled to lock the selected preferred lightning-catching blades in a vertically upward position as the target lightning-catching blades, and the auxiliary grounding device installed between the main shaft and the tower is closed.

[0042] Specifically, upon receiving a lightning protection shutdown command, the controller first needs to determine which blade will take on the lightning protection role. The system calls the classification list generated in step S3 and first searches the list of preferred lightning protection blades. If a blade is in the list (e.g., blade A and blade C), the system further compares their real-time resistance values ​​Ra and Rc, selecting the blade with the smallest absolute resistance value (let's say blade A) as the target lightning protection blade. If the list of preferred lightning protection blades is empty (meaning all blades have slightly high resistance but are not open-circuited), the system searches the list of backup lightning protection blades, again selecting the blade with the smallest resistance value as the target lightning protection blade. This process abandons the traditional random or fixed shutdown mode. Through physical-level resistance screening, it ensures that the lightning current always flows to the ground through the lowest impedance and most reliable connection, minimizing the risk of blade bursting or internal arcing due to poor contact of the down conductor.

[0043] Simultaneously with selecting the target blade, the nacelle begins horizontal attitude adjustment. The controller reads the values ​​from the four electric field sensors (front, rear, left, and right) of the nacelle and identifies the sensor with the highest value by comparison. For example, if the left sensor reading is significantly higher than the other three, the center of the lightning cloud is determined to be on the left side of the nacelle. Then, the yaw motor starts, driving the nacelle to rotate until the front of the nacelle (hub direction) is directly facing the direction of the strongest electric field. During this process, the nacelle, typically constructed of metal or conductive composite material, is positioned with its front facing the direction of the incoming lightning strike. This allows the nacelle shell to shield the delicate internal electrical equipment, reducing damage from lateral lightning strikes to the non-conductive areas of the nacelle sidewalls. Furthermore, it ensures that the rotor plane is perpendicular to the direction of the lightning electric field, providing the optimal geometric basis for subsequent blade positioning.

[0044] After the nacelle is aligned, the target lightning-catching blade needs to be precisely positioned at its highest point. Specifically, the pitch control system, in conjunction with generator torque control, drives the turbine to rotate slowly until the selected target lightning-catching blade is at the 12 o'clock position (vertically upward). The system then reads the values ​​from the turbine position encoder to determine if the angular deviation of the target blade is within ±5 degrees. If so, the mechanical brake disc on the high-speed or low-speed shaft is immediately engaged to mechanically lock the main shaft and prevent the turbine from rotating. If not, the torque is fine-tuned until the error requirement is met. In this way, the blade with the best lightning-catching performance is placed at the highest point. Utilizing the principle of point discharge, this position becomes the location with the most severe electric field distortion in the entire unit, thereby actively attracting lightning leaders and acting as lightning rods to protect the anemometer equipment at the rear of the nacelle and the nacelle itself. The mechanical locking prevents the turbine from rotating unexpectedly due to strong thunderstorm winds, ensuring the stability of the lightning strike path.

[0045] Then, different pitch maneuvers are performed on different blades. Specifically, the target lightning-catching blade at the 12 o'clock position has its pitch angle adjusted to 0 degrees (fully open). At this time, the blade's maximum windward surface faces the direction of the incoming lightning, maximizing the exposed area of ​​the blade tip lightning arrester. The other two blades at the 4 o'clock and 8 o'clock positions have their pitch angle adjusted to 90 degrees (feathered position). At this time, the blades face the lightning direction with their thinnest trailing or leading edge. The top blade at the 0-degree pitch angle has the largest projected area and the most prominent tip, making it highly likely to induce an upward leader and ensure lightning interception. The two lower blades are in a feathered state, with minimal aerodynamic drag, and their tip electric field concentration is significantly lower than that of the top blade at the 0-degree angle, thus suppressing the probability of non-target blades being struck by side lightning.

[0046] Simultaneously with the mechanical structure locking, the electrical connection path also changes. When the feedback signal from the spindle's mechanical brake action confirms the locked state, the control system immediately issues a command to close the auxiliary grounding device (such as a high-current carbon brush or clamp driven by a pneumatic actuator) installed between the spindle and the tower. During normal operation, the spindle relies on bearings for support, and the oil film within the bearings provides insulation. In the event of a lightning strike, without a bypass, the high-voltage lightning current will rupture the oil film, creating an electric spark (electrolytic erosion) between the balls and raceways, completely destroying the spindle bearings. After the auxiliary grounding device is closed, it provides a physically contacting metal channel with an impedance far lower than that of the bearing oil film, directly introducing the lightning current from the spindle into the tower and discharging it to the ground, achieving absolute protection for the core components of the transmission chain.

[0047] Furthermore, in embodiments of the present invention, a post-lightning strike self-test step is included after step S5: After the lightning strike event is detected to have ended and the ambient electric field strength has decreased, the loop resistance detection unit is restarted to detect the ground resistance value of the target lightning arresting blade. The ground resistance value after a lightning strike is compared with the ultimate withstand resistance threshold. If it is greater than the ultimate withstand resistance threshold, the blade is marked as a faulty blade.

[0048] Specifically, based on the active protection process, after step S5 is completed, that is, after the unit completes attitude lock and successfully resists the risk of lightning strike, the system will not directly resume normal power generation, but will execute the following post-processing logic.

[0049] Once the system detects that the external electric field sensor reading has fallen below the first-level warning threshold (E1), or after a significant lightning current discharge event has ended as detected by the current sensor, the controller sends a command to the loop resistance detection unit to force the test current to be applied again to the target lightning-absorbing blade that was just used for lightning protection. The system then reads its latest resistance to ground, recorded as Rnew. The system calls the preset limit withstand resistance threshold (Rlimit, e.g., 1 ohm). If Rnew > Rlimit, or if Rnew experiences an open-circuit abrupt change in resistance compared to the value before the lightning strike (e.g., becoming infinite), it is determined that the down conductor or lightning arrester inside the blade has melted or been damaged in the lightning strike. At this point, the system immediately updates the blade's health status to fault and adds it to the blacklist in the control system's database. Until manually reset by maintenance personnel, this blade will be strictly prohibited from use as a target lightning-absorbing blade during the next thunderstorm.

[0050] In this way, this embodiment prevents the system from mistakenly selecting a damaged blade (such as a burnt-out down conductor) to receive the lightning strike during the next thunderstorm through immediate self-check after the lightning strike, thereby avoiding blade bursting accidents caused by reusing failed blades.

[0051] In addition, in the embodiments of the present invention, the method further includes that if the environmental electric field strength exceeds the first warning threshold but does not exceed the second action threshold, the unit is maintained in power generation operation, and the resistance detection in step S2 is repeatedly performed at a first preset time interval. In other words, between step S1 (first-level warning) and step S4 (second-level action / shutdown), there is a potential time window when the environmental electric field is relatively high (E1 < E < E2), but it has not reached the level where shutdown is necessary. To ensure the real-time effectiveness of the data, the system executes the following logic. The unit maintains a normal grid-connected power generation operation state without shutdown. A short time interval T (for example, every 10 minutes) is set, and the system periodically repeats the resistance detection action in step S2. The resistance values Ra, Rb, and Rc of blades A, B, and C are updated in real time, and the sorted list of preferred lightning-receiving blades is refreshed in real time according to the latest resistance values. For example, at time T0, the resistance of blade A is the smallest, but at time T1, due to the centrifugal force or vibration generated by blade A rotating with the wind turbine, the connection of its down-lead joint becomes loose and the resistance suddenly increases. At this time, the system will immediately adjust blade B to the target lightning-receiving blade with the first priority. Once the sudden increase in the environmental electric field triggers the shutdown instruction in step S4, the system will directly call the most recently refreshed sorting result to lock the wind turbine. During the operation of the wind turbine generator, the connection state of the down-lead may change dynamically due to mechanical vibration, temperature change, or centrifugal force. This embodiment ensures that when lightning strikes, the system relies on the most reliable hardware state at the current moment rather than the outdated data at the beginning of the storm, significantly improving the accuracy and robustness of decision-making.

[0052] In addition, the present invention may further include a full-fault protection mode. That is, when it is determined in step S3 that all three blades are faulty blades, step S5 is not executed, but instead, all three blades are forced to be adjusted to the 90-degree feathering state, and the wind turbine is controlled to rotate so that any two blades are in a Y-shaped upper-open state, and at the same time, the auxiliary grounding device is closed.

[0053] Specifically, when the detection results of steps S2 and S3 show that all three blades of the wind turbine do not meet the safety requirements (i.e., the ground resistance values ​​of all three blades are greater than the ultimate withstand resistance threshold Rlimit), it indicates that relying on the blades to intercept lightning is extremely dangerous. At this time, the system triggers the highest priority full-fault protection mode. The system disables the instruction to "lock the blades at the 12 o'clock position" in step S5, because the blades have no conductivity at this time, and placing them at the highest point will only attract lightning strikes and cause physical damage. The control pitch system forces all blades into a 90-degree feathering state to reduce the blade frontal area and the accumulation of electric field at the tips. The control yaw and braking system locks the rotor in an inverted Y-shaped (or upper open Y-shaped) attitude. Specifically, the rotor azimuth angle is adjusted so that one blade points vertically to the ground (6 o'clock position), while the other two blades point diagonally upwards (10 o'clock and 2 o'clock positions), respectively. At the same time, regardless of the blade state, the auxiliary grounding device (such as carbon brush or brake grounding) between the main shaft and the tower is forcibly closed.

[0054] When all blades fail, one blade is positioned vertically downwards and the other two angled upwards. Compared to a single blade vertically upwards, this significantly reduces the overall height of the rotor. Given the selectivity of lightning strikes, reducing the height effectively decreases the probability of lightning leader lock-in. Furthermore, even if the blades cannot divert current, lightning can still strike the tail or side of the nacelle. By maintaining the auxiliary grounding device closed even in full-failure mode, a bypass path is forcibly created between the nacelle, main shaft, auxiliary grounding, and tower. This ensures that even in the event of a lightning strike, current will not flow through the precision main shaft bearings, thus avoiding the costly failure of bearing electrolytic corrosion.

[0055] Further as Figure 2 As shown, this embodiment of the invention also provides a wind turbine lightning protection system, which can be referred to in conjunction with the method described above. The system includes: The monitoring module is installed on the top of the cabin to monitor the intensity of the ambient electric field. The detection module activates the loop resistance detection unit when the ambient electric field strength exceeds the first-level warning threshold, and detects the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. The classification module categorizes the three blades based on their resistance to ground and selects the preferred lightning-catching blades. The judgment module continues to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, the shutdown and lightning protection strategy is executed. The execution module, in the shutdown lightning protection strategy, controls the yaw system and pitch system of the wind turbine, locks the selected preferred lightning-absorbing blades in a vertically upward position as the target lightning-absorbing blades, and closes the auxiliary grounding device installed between the main shaft and the tower.

[0056] Figure 3An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 3 As shown, the electronic device may include a processor 810, a communications interface 820, a memory 830, and a communication bus 840. The processor 810, communications interface 820, and memory 830 communicate with each other via the communication bus 840. The processor 810 can call logical instructions from the memory 830 to execute the wind turbine lightning protection method described above.

[0057] Furthermore, the logical instructions in the aforementioned memory 830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0058] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the wind turbine lightning protection method provided by the above methods.

[0059] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the wind turbine lightning protection method provided by the above methods.

[0060] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0061] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0062] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for lightning protection of wind turbine generators, characterized in that, include: Step S1: Monitor the ambient electric field strength using an electric field sensor installed on the top of the cabin; Step S2: When the ambient electric field strength exceeds the first-level warning threshold, the loop resistance detection unit is activated to detect the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. Step S3: Classify the three blades according to the ground resistance value and select the preferred lightning protection blade; Step S4: Continue to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, execute the shutdown and lightning protection strategy. Step S5: In the shutdown lightning protection strategy, control the yaw system and pitch system of the wind turbine to lock the selected preferred lightning protection blades in a vertically upward position as the target lightning protection blades, and close the auxiliary grounding device installed between the main shaft and the tower.

2. The method for lightning protection of wind turbine generators according to claim 1, characterized in that, Step S3 specifically includes: Set the standard safety resistance threshold and the ultimate withstand resistance threshold; If the ground resistance value of a certain blade is less than the standard safety resistance threshold, the blade is marked as a preferred lightning protection blade. If the ground resistance value of a blade is greater than or equal to the standard safety resistance threshold and less than the ultimate withstand resistance threshold, the blade is marked as a spare lightning protection blade. If the ground resistance value of a blade is greater than or equal to the ultimate withstand resistance threshold, the blade is marked as a faulty blade.

3. The method for lightning protection of wind turbine generators according to claim 2, characterized in that, The selection of the target lightning-absorbing blade in step S5 specifically includes: From the list of preferred lightning protection blades, select the blade with the lowest ground resistance value as the target lightning protection blade; If no preferred lightning protection blade is available, the blade with the lowest ground resistance value is selected from the list of blades marked as spare lightning protection blades as the target lightning protection blade.

4. The method for lightning protection of wind turbine generators according to claim 3, characterized in that, In step S1, four electric field sensors are set up and installed in the front, rear, left and right positions on the top of the cabin, respectively. The control of the yaw system in step S5 specifically includes: By comparing the values ​​from the four electric field sensors, the location of the strongest electric field intensity can be determined. If the direction of the strongest electric field is not directly in front of the nacelle, the yaw motor is activated until the front of the nacelle is aligned with the direction of the strongest electric field.

5. The method for lightning protection of wind turbine generators according to claim 4, characterized in that, The step S5 of locking the preferred lightning-absorbing blade in a vertically upward position specifically includes: Control the wind turbine to rotate until the target lightning rod is at the 12 o'clock position; Detect the wind turbine locking angle error. If the error is within the preset range, engage the mechanical brake disc to lock the main shaft.

6. The method for lightning protection of wind turbine generators according to claim 5, characterized in that, The specific steps in step S5, including controlling the pitch system, include: Adjust the pitch angle of the target flash blade at the 12 o'clock position to 0 degrees fully open. Adjust the pitch angle of the other two blades to 90 degrees in a feathering state.

7. The method for lightning protection of wind turbine generators according to claim 6, characterized in that, The auxiliary grounding device is a mechanical contact carbon brush or a switch, and closing the auxiliary grounding device in step S5 specifically includes: While the main spindle is mechanically braked and locked, the auxiliary grounding device is activated to allow direct connection between the main spindle and the tower through physical contact points, thereby bypassing the main spindle bearing.

8. The method for lightning protection of wind turbine generators according to claim 7, characterized in that, Step S5 is followed by a post-lightning strike self-test step: After the lightning strike event is detected to have ended and the ambient electric field strength has decreased, the loop resistance detection unit is restarted to detect the ground resistance value of the target lightning arresting blade. The ground resistance value after a lightning strike is compared with the ultimate withstand resistance threshold. If it is greater than the ultimate withstand resistance threshold, the blade is marked as a faulty blade.

9. The method for lightning protection of wind turbine generators according to claim 7, characterized in that, Also includes: If the ambient electric field strength exceeds the first-level warning threshold but does not exceed the second-level action threshold, the unit continues to generate electricity and the resistance detection in step S2 is repeated according to the first preset time interval.

10. A wind turbine lightning protection system, characterized in that, include: The monitoring module is installed on the top of the cabin to monitor the intensity of the ambient electric field. The detection module activates the loop resistance detection unit when the ambient electric field strength exceeds the first-level warning threshold, and detects the ground resistance value of the lightning protection channel of each of the three blades of the wind turbine. The classification module classifies the three blades according to the ground resistance value and selects the preferred lightning-catching blades. The judgment module continues to monitor the ambient electric field strength. When the ambient electric field strength exceeds the secondary action threshold, the shutdown and lightning protection strategy is executed. The execution module, in the shutdown lightning protection strategy, controls the yaw system and pitch system of the wind turbine, locks the selected preferred lightning-absorbing blades in a vertically upward position as the target lightning-absorbing blades, and closes the auxiliary grounding device installed between the main shaft and the tower.

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