Method and system for detecting a lightning protection system of a wind turbine

Abstract

The application provides a detection method and system of a lightning protection system of a wind turbine, and relates to the technical field of lightning protection system detection, and comprises the following steps: simulating lightning by pulse current, determining a pulse injection period according to the material of a down conductor and the total number of connection nodes of the down conductor and the wind turbine; periodically injecting pulse current into a lightning receptor on a blade according to the pulse injection period; sequentially arranging M detection points along the transmission path of the down conductor, and arranging a group of detection devices on each point; judging whether there is an anomaly based on the detected current value through an anomaly detection model, and outputting an abnormal line range when there is an anomaly; and determining the time interval of the next detection based on the impedance life curve of the grounding resistance and the currently detected measured impedance. The application has the advantages of improving the accuracy and pertinence of the detection of the lightning protection system of the wind turbine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lightning protection system detection, in particular to a detection method and system for a lightning protection system of a wind turbine. BACKGROUND

[0002] Wind turbines are prone to lightning strikes during operation. In order to prevent lightning strikes from causing blade damage, a lightning arrester and down conductor are usually arranged therein to achieve lightning protection by conducting lightning current into the ground.

[0003] In order to ensure the normal operation of the lightning protection system, it is generally periodically detected. The detection can usually be performed by pulse simulation lightning. However, the detection method of the prior art usually has the following problems: the pulse current injection frequency is relatively fixed, and the interval between two detections also lacks targeted setting, that is, the existing detection scheme does not consider the lightning protection system characteristics of each wind turbine. Based on this general scheme, the pulse injection frequency may be too fast for some wind turbines, causing unnecessary life damage to the lightning protection system of the wind turbine, or the pulse injection frequency is too low or the interval between two detections is too long, resulting in failure to discover problems in time.

[0004] Therefore, there is an urgent need for an improved detection method that can adaptively adjust the pulse injection period and dynamically determine the next detection time according to the characteristics of the lightning protection system of different wind turbines, thereby improving the accuracy and pertinence of the detection of the lightning protection system of the wind turbine. SUMMARY

[0005] The present application aims to provide a detection method and system for a lightning protection system of a wind turbine, which can improve the accuracy and pertinence of the detection of the lightning protection system of the wind turbine.

[0006] The present application is implemented by the following technical solutions:

[0007] The detection method for the lightning protection system of the wind turbine comprises the following steps:

[0008] The pulse current simulates lightning, and the pulse injection period is determined according to the material of the down conductor and the total number of connection nodes between the down conductor and the wind turbine;

[0009] The pulse current is periodically injected into the lightning arrester on the blade according to the pulse injection period;

[0010] M detection points are sequentially arranged along the transmission path of the down conductor, and a set of detection devices is arranged at each point, and the first detection point is arranged at the beginning of the transmission path, and the detection devices are used to continuously detect the current value of the corresponding detection point;

[0011] Based on the detected current value, an abnormality detection model is used to determine whether there is an abnormality, and an abnormal line range is output when there is an abnormality.

[0012] According to the impedance life curve of the grounding resistance and the current detected impedance, a time interval of the next detection is determined.

[0013] Preferably, the method for determining the pulse injection period is:

[0014] defining a standard pulse injection period;

[0015] obtaining a thermal diffusivity of the down conductor according to the material;

[0016] determining a correction coefficient of the pulse injection period according to the thermal diffusivity and the total number of connection nodes;

[0017] obtaining the pulse injection period based on the product of the standard pulse injection period and the correction coefficient.

[0018] Preferably, the method for obtaining the thermal diffusivity of the down conductor according to the material is:

[0019] ;

[0020] wherein, is the thermal diffusivity of the down conductor, is the thermal conductivity of the down conductor, is the material density of the down conductor, is the specific heat capacity of the down conductor.

[0021] Preferably, the method for obtaining the correction coefficient is:

[0022] ;

[0023] ;

[0024] wherein, is the correction coefficient, is a preset upper limit of the correction coefficient, is an intermediate parameter, is a preset threshold value of the thermal diffusivity, is a constant not greater than 1, is a positive number not greater than 1, N is the total number of connection nodes of the down conductor and the fan, and N' is a preset connection quantity threshold.

[0025] Preferably, the judgment method of the abnormality detection model is:

[0026] According to the current values of the continuous detection points, the feature data of each detection point is obtained, and the feature data includes the distance from the detection point to the first detection point, the current peak value and the corresponding time;

[0027] extracting a time residual and an amplitude residual of each of the detection nodes based on the feature data, the time residual being used to describe an error between an actual time of arrival of the current peak and an ideal time, and the amplitude residual being used to describe an error between a measured current peak and an ideal current peak;

[0028] judging whether there is an abnormality based on the time residual and the amplitude residual, and outputting an abnormal line range when there is an abnormality.

[0029] Preferably, the method for obtaining the time residual is:

[0030]

[0031] the method for obtaining the amplitude residual is:

[0032] ;

[0033]

[0034] wherein, and are the time residual and the amplitude residual of the kth detection node respectively, , and are the current peak, the corresponding time and the distance to the first detection node of the kth detection node respectively, v is the propagation speed of the pulse current in the down conductor, and m is the amplitude attenuation constant of the pulse current in the down conductor.

[0035] Preferably, the method for judging whether there is an abnormality based on the time residual and the amplitude residual is:

[0036] obtaining the median of all the time residuals and the median of all the amplitude residuals ;

[0037] obtaining the difference between the time residual of the kth detection node and the median , obtaining the difference between the amplitude residual of the kth detection node and the median ;

[0038] obtaining the median of all and the median of all ; obtaining the time residual evaluation parameter and the amplitude residual evaluation parameter

[0039] of the kth detection node respectively: ​​​

[0040] ;

[0041] ;

[0042] obtaining a comprehensive evaluation parameter of the kth detection point :

[0043]

[0044] wherein, and are the weight and the amplitude residual evaluation parameter of the time residual evaluation parameter respectively;

[0045] when the is greater than a preset threshold, it is judged that there is an abnormality between the kth detection point and the k-1th detection point of the down conductor 1.

[0046] Preferably, the method for determining the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the currently detected measured impedance is:

[0047] The time interval from the first detection to the second detection is a preset time;

[0048] The fitting function z=f(t) of the impedance of the grounding resistance z changing with the use time t is constructed through fitting experiments, and the fitting function is used as the impedance life curve;

[0049] Obtaining a plurality of impedances, including the theoretical impedance and the measured impedance of the grounding resistance at the k-1th detection, and the theoretical impedance and the measured impedance of the grounding resistance at the kth detection, wherein the kth detection is the current detection, and k is an integer not less than 2;

[0050] Obtaining the time interval from the k-2th detection to the k-1th detection ;

[0051] Determining the current time interval decay coefficient based on the plurality of impedances and the use time length of the grounding resistance up to the current detection;

[0052] Taking the product of and the current time interval decay coefficient as the time interval from the current detection to the next detection.

[0053] Preferably, the current time interval decay coefficient is determined based on the plurality of impedances and the use time length of the grounding resistance up to the current detection ​The method is:

[0054] ;

[0055] Wherein, Is the initial impedance of the grounding resistance, min is the minimum function, max is the maximum function, s is a positive number not greater than 0.5.

[0056] The application also provides a detection system of the lightning protection system of the wind driven generator, applied to the detection method of the lightning protection system of the wind driven generator, comprising:

[0057] The lightning simulation module is used for simulating lightning through pulse current, and the pulse injection period is determined according to the material of the down conductor and the number of lightning arresters;

[0058] The pulse injection module is used for periodically injecting pulse current into the lightning arresters on the blade according to the pulse injection period;

[0059] The detection module is used for sequentially arranging a plurality of detection points along the transmission path of the down conductor, and arranging a group of detection devices on each point, and the detection devices are used for continuously detecting the current value of the corresponding detection point;

[0060] The abnormality judgment module is used for judging whether there is an abnormality based on the detected current value through an abnormality detection model, and outputting an abnormal line range when there is an abnormality;

[0061] The detection time determination module is used for determining the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the measured impedance of the current detection.

[0062] The technical scheme of the application has at least the following advantages and beneficial effects:

[0063] The application adaptively determines the pulse injection period according to the material of the down conductor and the number of connection nodes, and then reasonably sets the injection frequency according to the lightning protection system characteristics of different wind driven generators, avoids the life damage of the lightning protection system caused by too fast injection, and also avoids the insufficient comprehensiveness of abnormality detection caused by too slow injection;

[0064] The application dynamically determines the time interval from the current detection to the next detection by using the impedance life curve of the grounding resistance and the real-time measured impedance value, so that the detection period can be adjusted according to the life change characteristics of the lightning protection system, the detection period is shortened when the impedance index deteriorates, the hidden danger of the lightning protection system can be found in time, and the timeliness and reliability of detection are improved;

[0065] The application can quickly identify abnormal conditions in the lightning protection system by distributing detection points and analyzing current values through an abnormality detection model, and outputting an abnormal line range;

[0066] The detection process of the present application can be implemented without disassembling the fan or damaging the existing structure, the detection means is simple and can be combined with the daily operation and maintenance process of the fan, and is convenient for popularization and implementation. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 A flowchart of the detection method of the lightning protection system of the wind driven generator provided for the embodiment 1 of the present application is shown in the figure.

[0068] Figure 2 A structure diagram of the detection system of the lightning protection system of the wind driven generator provided for the embodiment 2 of the present application is shown in the figure. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0070] Embodiment 1

[0071] The embodiment provides a detection method of the lightning protection system of the wind driven generator, referring to Figure 1 , comprising the following steps:

[0072] Step S1: simulate lightning by pulse current, and determine the pulse injection period according to the material of the down conductor and the total number of the connection nodes of the down conductor and the fan.

[0073] In the embodiment, the method for determining the pulse injection period is:

[0074] define a standard pulse injection period;

[0075] acquire the thermal diffusivity of the down conductor according to the material;

[0076] determine a correction coefficient of the pulse injection period according to the thermal diffusivity and the total number of the connection nodes;

[0077] obtain the pulse injection period based on the product of the standard pulse injection period and the correction coefficient.

[0078] Wherein, the method for acquiring the thermal diffusivity of the down conductor according to the material is:

[0079] ;

[0080] Wherein, is the thermal diffusivity of the down conductor, is the thermal conductivity of the down conductor, The material density of the down conductor is... The specific heat capacity of the lead wire.

[0081] A higher thermal diffusivity means faster heat transfer and easier cooling. In other words, a lower thermal diffusivity in the downlead indicates a greater susceptibility to localized overheating or lifespan reduction when subjected to pulsed current surges, thus requiring more cooling time. Secondly, the number of connection nodes directly affects the distribution characteristics and loss level of the pulsed current, depending on the connection method between the downlead and the fan. More nodes result in a more complex current transmission path, making localized anomalies more likely and necessitating a longer injection cycle.

[0082] Based on this, the method for obtaining the correction coefficient is as follows:

[0083] ;

[0084] ;

[0085] in, The correction coefficient is... This is the upper limit of the preset correction coefficient value. For intermediate parameters, The preset thermal diffusivity threshold, A constant not greater than 1 N is a positive number not greater than 1, where N is the total number of connection nodes between the down conductor and the wind turbine, and N' is a preset connection number threshold.

[0086] In the calculation of the correction factor, 1 and The lower and upper limits of the correction coefficient are used to limit its range of values, preventing the correction coefficient from deviating too much from the normal level when the calculated value is too abnormal, and avoiding extreme shortening or lengthening. A value of 3-5 is acceptable when the number of connected nodes is sufficiently small (less than 5). ), parameters obtained solely based on the thermal diffusivity Calculate the correction factor; when the number of connected nodes is too large, it will... Continue on the basis Amplification correction factor, The coefficient based on the number of connected nodes can be mapped to a parameter greater than 1 and less than 2, resulting in a smooth mapping that doesn't amplify excessively. Slow diffusion means... When it's too small, it will be The injection cycle is increased by mapping the coefficient to a value greater than 1.

[0087] It should be noted that, as an implementation case, The thermal diffusion coefficient of the most commonly used down conductor material can be selected, and the most commonly used safe injection period of the down conductor test of this material is taken as the standard pulse injection period under the condition of fewer connection nodes. The influence degree can be used to amplify or reduce The influence degree can be taken as 1 in the case of strong influence, and can be taken as 0.3-0.6 in general. The influence degree can be used to amplify or reduce

[0088] In the lightning protection system, in addition to the lightning arrester, the down conductor is also connected to multiple nodes of the wind turbine, such as the hub, the metal support of the wind turbine, etc. There can be local impedance and contact resistance at each connection node of the down conductor, and the current waveform at the node is prone to stacking interference. In the prior art, the injection period of the pulse current is usually a fixed value, and cannot be differentiated according to the structural differences of different wind turbine lightning protection systems. For down conductors with poor heat diffusion capacity or more connection nodes, the fixed period can be too frequent, which can easily cause local overheating or accelerate the service life decay of the components, and can also cause interference to the detection. In addition, from the perspective of heat dissipation, the pulse current passing through the node can more easily cause resistive heating, and the superposition effect of multiple nodes can also slow down the overall cooling speed. In addition to the above considerations, it is also desirable to inject as continuously as possible to test the performance while giving the lightning arrester enough time to dissipate heat. The detection of the lightning protection system is expected to be carried out in a way that minimizes the impact on the service life of the lightning protection system, so the injection scheme of the pulse current in the embodiment is calculated in a targeted manner to minimize the negative impact on the service life of the lightning protection system while ensuring the detection effect.

[0089] Step S2: periodically injecting a pulse current into the lightning arrester on the blade according to the pulse injection period.

[0090] In this step, due to the setting of step S1, the down conductor has enough recovery time in multiple aspects, and can be directly injected at multiple points at the same time or injected at a single point. Safety and reliability can be ensured in diversified tests.

[0091] Step S3: sequentially setting M detection points along the transmission path of the down conductor, and arranging a set of detection devices at each point, and the first detection point is set at the beginning of the transmission path, and the detection devices are used to continuously detect the current value of the corresponding detection point.

[0092] Step S4: based on the detected current value, determining whether there is an anomaly through an anomaly detection model, and outputting an abnormal line range when there is an anomaly.

[0093] As a preferred scheme, the judgment method of the anomaly detection model is:

[0094] Based on the current values ​​of the continuous detection points, the characteristic data of each detection point is obtained. The characteristic data includes the distance from the detection point to the first detection point, the peak current, and the corresponding time.

[0095] The time residual and amplitude residual of each detection node are extracted based on the feature data. The time residual is used to describe the error between the actual time and the ideal time when the current peak arrives, and the amplitude residual is used to describe the error between the measured current peak and the ideal current peak.

[0096] The system determines whether an anomaly exists based on the time residual and the amplitude residual, and outputs the range of the abnormal line when an anomaly exists.

[0097] Specifically, the method for obtaining the time residual is as follows:

[0098]

[0099] The method for obtaining the amplitude residual is as follows:

[0100] ;

[0101]

[0102] in, and These are the time residual and the amplitude residual at the k-th detection point, respectively. , and Let v be the peak current at the k-th detection point, the corresponding time, and the distance to the first detection point, respectively; v be the propagation speed of the pulse current in the down conductor; and m be the amplitude attenuation constant of the pulse current in the down conductor.

[0103] The time residual compares the difference between the actual peak current arrival time and the ideal propagation time. This value can be used to assess anomalies; for example, if there is an impedance anomaly or increased loss in a certain section of the down conductor, the current propagation speed will deviate. The amplitude residual describes the difference between the measured peak current and the ideal attenuation value. If there is poor contact or localized loss anomaly in a certain section of the down conductor, the deviation will be larger. Therefore, based on the results obtained above, the preferred method for determining whether an anomaly exists based on the time residual and the amplitude residual is as follows:

[0104] Obtain the median of all the aforementioned time residuals. and the median of all the aforementioned amplitude residuals ;

[0105] Obtain the time residual and median of the k-th detection point respectively. The difference , respectively, the difference between the amplitude residual and the median of the kth detection point ;

[0106] Obtain the median of all and the median of all ;

[0107] respectively, the time residual evaluation parameter and the amplitude residual evaluation parameter of the kth detection point:

[0108] ;

[0109] ;

[0110] Obtain the comprehensive evaluation parameter of the kth detection point:

[0111]

[0112] wherein, and are the weights of the time residual evaluation parameter and the amplitude residual evaluation parameter respectively;

[0113] When is greater than a preset threshold, it is determined that there is an anomaly between the kth detection point and the k-1th detection point of the down conductor 1.

[0114] Through the double feature analysis of the time residual and the amplitude residual, not only can the defects caused by the abnormal current propagation speed be found, but also the defects caused by the abnormal current amplitude attenuation can be found, thereby improving the comprehensiveness of anomaly detection. When there is an anomaly between a certain detection point and an adjacent detection point, the abnormal section can be directly located, the fault troubleshooting range is significantly reduced, and the maintenance efficiency is improved. In each comparison of the embodiment, the median is used as the reference, the median is not affected by extreme values, and is more robust than the average value.

[0115] Step S5: Determine the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the measured impedance of the current detection.

[0116] In the embodiment, the method for determining the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the measured impedance of the current detection is:

[0117] ​​​The time interval between the first detection and the second detection adopts a preset time, which can adopt a standard detection period interval;

[0118] The fitting function z=f(t) of the impedance of the grounding resistor z varying with the use time t is constructed by fitting the experiments, and the fitting function is the impedance life curve;

[0119] A plurality of impedances are acquired, including the theoretical impedance of the grounding resistor in the k-1th detection and the measured impedance , the theoretical impedance of the grounding resistor in the kth detection and the measured impedance , the kth detection is the current detection, and k is an integer not less than 2;

[0120] The time interval between the k-2th detection and the k-1th detection is acquired ;

[0121] A current time interval attenuation coefficient is determined based on the plurality of impedances and the use time length of the grounding resistor until the current detection;

[0122] The product of and the current time interval attenuation coefficient is taken as the time interval between the current detection and the next detection.

[0123] The method for determining the current time interval attenuation coefficient based on the plurality of impedances and the use time length of the grounding resistor until the current detection is ;

[0124] ;

[0125] Wherein, the initial impedance of the grounding resistor is , min is a minimum function, max is a maximum function, and s is a positive number not greater than 0.5.

[0126] In actual use, the impedance of the grounding resistor will increase with the use time due to sudden corrosion and other influences, and the failure rate in the life thereof can be easily quantified, so the grounding resistor is selected as the reference value for determining the detection interval, the measurement is easy to implement, the calculation is simple, and the result is reliable. In the above calculation, can be regarded as the failure rate of the grounding resistor under the current measured impedance First, 1 is subtracted from the failure rate to obtain a basic coefficient for determining the current time interval attenuation coefficient, that is, the higher the failure rate, the smaller the basic coefficient, because the higher the failure rate represents a greater risk of damage, and the detection frequency needs to be improved. The difference between the actual change of the impedance and the ideal change of the impedance during the two detections can be evaluated, and if the actual change is too large, it can be judged that the deterioration is too fast, The value of the lightning resistance will become smaller. under the action of the lightning resistance, When the value of the lightning resistance is not less than 1, it indicates that the service life consumption of the lightning resistance is good, and the basic coefficient will not be further reduced. The faster the actual lightning resistance deteriorates, The smaller the value of the lightning resistance is, the more the basic coefficient will be further reduced, The minimum degree of reduction can be limited to avoid unnecessary detection too frequently. It is particularly pointed out that the value of the lightning resistance impedance can also be directly used to evaluate whether the lightning resistance of the lightning protection system is abnormal.

[0127] Embodiment 2

[0128] The embodiment provides a detection system of a lightning protection system of a wind turbine, which is applied to the detection method of the lightning protection system of the wind turbine, and refers to Figure 2 , comprising:

[0129] A lightning simulation module is configured to simulate lightning by pulse current, and determine a pulse injection period according to the material of the down conductor and the number of lightning arresters;

[0130] A pulse injection module is configured to periodically inject pulse current into the lightning arresters on the blade according to the pulse injection period;

[0131] A detection module is configured to sequentially arrange a plurality of detection points along the transmission path of the down conductor, and arrange a set of detection devices on each point, which are configured to continuously detect the current value of the corresponding detection point;

[0132] An abnormality judgment module is configured to judge whether there is an abnormality based on the detected current value through an abnormality detection model, and output an abnormal line range when there is an abnormality.

[0133] A detection time determination module is configured to determine the time interval from the current detection to the next detection according to the impedance life curve of the lightning resistance and the measured impedance of the current detection.

[0134] The above is only a preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of detecting a lightning protection system of a wind power generator, characterized in that The method comprises the following steps: The lightning is simulated by pulse current, and the pulse injection period is determined according to the material of the down conductor and the total number of connection nodes of the down conductor and the fan; The pulse current is periodically injected into the lightning receptor on the blade according to the pulse injection period; M detection points are sequentially arranged along the transmission path of the down conductor, and a group of detection devices are arranged at each point, and the first detection point is arranged at the beginning of the transmission path, and the detection devices are used for continuously detecting the current value of the corresponding detection point; Based on the detected current value, whether there is an anomaly is judged by an anomaly detection model, and the abnormal line range is output when there is an anomaly; The time interval from the current detection to the next detection is determined according to the impedance life curve of the grounding resistance and the measured impedance of the current detection; The judgment method of the anomaly detection model is: According to the current value of the continuous detection point, the feature data of each detection point is obtained, and the feature data includes the distance from the detection point to the first detection point, the current peak value and the corresponding time; Based on the feature data, the time residual and the amplitude residual of each detection point are extracted, the time residual is used to describe the error between the actual time and the ideal time when the current peak value arrives, and the amplitude residual is used to describe the error between the measured current peak value and the ideal current peak value; According to the time residual and the amplitude residual, whether there is an anomaly is judged, and the abnormal line range is output when there is an anomaly; The acquisition method of the time residual is: ； The acquisition method of the amplitude residual is: ； ； wherein, and are the time residual and the amplitude residual of the kth detection point, respectively, , and are the current peak value, the corresponding time and the distance to the first detection point of the kth detection point, respectively, v is the propagation speed of the pulse current in the down conductor, and m is the amplitude attenuation constant of the pulse current in the down conductor. The method for judging whether there is an anomaly according to the time residual and the amplitude residual is: obtaining a median of all the time residuals and a median of all the amplitude residuals ; Obtain the time residual and median of the k-th detection point respectively. The difference The amplitude residual and median of the k-th detection point are obtained respectively. The difference ; get all the median of and all the median of ; Residual evaluation parameters of time and amplitude are obtained respectively at the kth detection point and the amplitude : ； ； acquiring the comprehensive evaluation parameter of the kth detection point : ； wherein and are the weight and the amplitude residual evaluation parameter of the time residual evaluation parameter respectively; When If the difference is greater than a preset threshold, it is determined that there is an abnormality between the kth detection point and the k-1th detection point of the down conductor 1.

2. The lightning protection system for a wind power generator according to claim 1, wherein The method for determining the pulse injection period is: A standard pulse injection period is defined; The thermal diffusivity of the down conductor is obtained according to the material; The correction coefficient of the pulse injection period is determined according to the thermal diffusivity and the total number of connection nodes; The pulse injection period is obtained based on the product of the standard pulse injection period and the correction coefficient.

3. The lightning protection system for a wind power generator according to claim 2, wherein The method for obtaining the thermal diffusivity of the down conductor according to the material is: ； wherein is the thermal diffusivity of the down conductor, is the thermal conductivity of the down conductor, is the material density of the down conductor, is the specific heat capacity of the down conductor.

4. The lightning protection system for a wind power generator according to claim 3, wherein The acquisition method of the correction coefficient is: ； ； wherein, is the correction coefficient, is a preset upper limit of the correction coefficient value, is an intermediate parameter, is a preset thermal diffusion coefficient threshold value, is a constant not greater than 1, is a positive number not greater than 1, N is the total number of connection nodes of the down conductor and the fan, and N' is a preset connection quantity threshold value.

5. The lightning protection system for a wind power generator according to claim 1, wherein The method for determining the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the measured impedance of the current detection is: The time interval from the first detection to the second detection adopts a preset time; The fitting function z=f(t) of the impedance of the grounding resistance z changing with the use time t is constructed by fitting experiments, and the fitting function serves as the impedance life curve; Obtaining a plurality of impedances, including a theoretical impedance of the grounding resistance at the k-1th detection and a measured impedance , and a theoretical impedance of the grounding resistance at the kth detection and a measured impedance , the kth detection being a current detection, and k being an integer not less than 2. acquiring a time interval between the k-2nd detection and the k-1st detection ; A current time interval decay coefficient is determined based on a plurality of impedances and the use time length of the grounding resistance before the current detection; by The product of the current time interval decay coefficient and the current time interval is used as the time interval between the current detection and the next detection.

6. The lightning protection system for a wind power generator according to claim 5, wherein The current time interval attenuation coefficient is determined based on the use time length of the plurality of impedances and the current detected grounding resistance The method is as follows: ； wherein is an initial impedance of the grounding resistance, min is a function of finding a minimum value, max is a function of finding a maximum value, and s is a positive number not greater than 0.

5.

7. The detection system of the lightning protection system of the wind power generator, applied to the detection method of the lightning protection system of the wind power generator according to any one of claims 1-6, characterized in that, It comprises: A lightning simulation module is used to simulate lightning by pulse current, and the pulse injection period is determined according to the material of the down conductor and the number of lightning receptors; A pulse injection module is used to periodically inject pulse current into the lightning receptor on the blade according to the pulse injection period; A detection module is used to sequentially arrange a plurality of detection points along the transmission path of the down conductor, and a group of detection devices are arranged at each point, and the detection devices are used for continuously detecting the current value of the corresponding detection point; Anomaly judgment module, configured to judge whether there is an anomaly based on the detected current value through an anomaly detection model, and output an abnormal line range when there is an anomaly; The detection time determination module is configured to determine the time interval from the current detection to the next detection according to the impedance life curve of the grounding resistance and the measured impedance of the current detection.

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