System, method, and apparatus for inspecting wind turbine blades.

Abstract

A system according to the present disclosure comprises: a transmitter, for electromagnetic waves, mounted on a first unmanned aerial vehicle; a receiver, for electromagnetic waves, mounted on a second unmanned aerial vehicle; at least one processor communicatively linked to the transmitter and the receiver; and a memory that is communicatively linked to the at least one processor and that has stored therein multiple executable instructions. The multiple instruction causes the at least one processor to execute the following processes. The first process involves radiating electromagnetic waves from the transmitter to the rotation plane of blades of a wind power generation facility in a state where the first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotation plane of the blades. The second process involves receiving, by the receiver, reflected waves and / or diffracted waves generated at the blades through radiation of electromagnetic waves from the transmitter. The third process involves determining the presence or absence of an abnormality in the blades through a process of analyzing the reflected waves or diffracted waves received by the receiver.

Description

Technical Field

[0001] The present disclosure relates to a system, method, and apparatus for inspecting blades of a wind power generation facility.

Background Art

[0002] Infrastructure facilities require regular or irregular inspections. As an example of such infrastructure facilities, wind power generation facilities are known. In the case of wind power generation facilities, it is required to inspect whether there are any damages or deteriorations on the rotating blades.

[0003] As documents that disclose methods for inspecting blades of a wind power generation facility, Patent No. 6768983 and Patent No. 7022858 can be exemplified. Patent No. 6,768,983 introduces, as a conventional method, a method in which an operator checks the blade surface with a camera mounted on a camera or a drone that monitors the outside through an inspection opening on the tower outer wall. Patent No. 7,022,858 discloses a proposal regarding a photographing method when photographing the blade surface with a camera mounted on a drone.

[0004] However, inspection by a camera is easily affected by the weather. For example, at the time of backlighting, cloudy weather, and at night, even if there are damages, cracks, or defects on the blade, the damages may not be reflected in the camera. In addition, in image diagnosis of an image taken by a camera, it may not be possible to judge the bending or warping of the blade in some cases.

[0005] Since power generation is interrupted when the rotation of the blade is stopped, it is desirable that the inspection be carried out while the blade is rotating. For this reason, in order to photograph the damage of the blade with a camera, it is necessary to adjust the shutter speed according to the rotation speed of the blade. However, since it is necessary to increase the shutter speed when the rotation speed of the blade is high, if the resolution and brightness as the lens performance of the camera are low, the damage of the blade may not be accurately reflected.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Patent No. 6768983 [Patent Document 2] Patent No. 7022858 [Overview of the project] [Problems that the invention aims to solve]

[0007] This disclosure is made in view of the issues described above. The purpose of this disclosure is to enable inspection of wind turbine blades without being affected by blade rotation speed or weather conditions. [Means for solving the problem]

[0008] This disclosure provides a system for inspecting the blades of a wind turbine to achieve the above objective. The system of this disclosure comprises an electromagnetic wave transmitter mounted on a first unmanned aerial vehicle and an electromagnetic wave receiver mounted on a second unmanned aerial vehicle. The system of this disclosure further comprises at least one processor communicatively coupled to the transmitter and the receiver, and a memory storing a plurality of executable instructions, communicatively coupled to the at least one processor. The plurality of instructions are configured to cause the at least one processor to perform the following processes: The first process is to radiate electromagnetic waves from the transmitter toward the rotation surface of the blade, with the first and second unmanned aerial vehicles facing each other across the rotation surface of the blade, or with the rotation surface acting as a reflecting surface. The second process is to receive at least one of the reflected waves and diffracted waves generated on the blade by the radiation of electromagnetic waves from the transmitter with the receiver. The third process is to determine whether or not there is an abnormality in the blade by analyzing the reflected waves or diffracted waves received by the receiver.

[0009] Furthermore, this disclosure provides a method for inspecting the blades of a wind turbine to achieve the above objectives. The method of this disclosure includes the following steps: The first step is to radiate electromagnetic waves from a transmitter toward the rotating surface of a blade, with a first unmanned aerial vehicle and a second unmanned aerial vehicle facing each other across the rotating surface of the blade, or with the rotating surface acting as a reflecting surface. The second step is to receive at least one of the reflected waves and diffracted waves generated on the blade by the radiation of electromagnetic waves from the transmitter with a receiver. The third step is to determine whether or not there is an abnormality in the blade by analyzing the reflected waves or diffracted waves received by the receiver.

[0010] Furthermore, to achieve the above objective, this disclosure provides a device for inspecting the blades of a wind turbine. The device of this disclosure comprises an antenna, a receiving unit, and an analysis processing unit. The receiving unit is configured to receive at least one of the reflected waves and diffracted waves generated on the blade by the radiation of electromagnetic waves from a transmitter when the antenna is facing the electromagnetic wave transmitter across the rotation surface of the blade, or when the rotation surface is used as a reflecting surface. The analysis processing unit is configured to determine whether or not there is an abnormality in the blade by analyzing the reflected waves or diffracted waves received by the receiving unit. The analysis processing unit of the device of this disclosure may be implemented by a computer and a program. The program may be recorded on a computer-readable recording medium or provided via a network. [Effects of the Invention]

[0011] According to the system, method, and apparatus of this disclosure, reflected or diffracted waves generated on the blade by electromagnetic wave radiation from a transmitter are analyzed, and the presence or absence of abnormalities in the blade is determined based on the results of the analysis. This makes it possible to inspect the blades of a wind turbine without being affected by the rotational speed of the blade or weather conditions. [Brief explanation of the drawing]

[0012] [Figure 1]This figure illustrates an overview of a method for inspecting the blades of a wind turbine according to an embodiment of this disclosure. [Figure 2] This figure shows an example of the time variation of the direct wave received by a radio receiver when a radio transmitter emits radio waves toward the rotating surface of a blade. [Figure 3] This figure shows an example of the delay profile of diffracted and reflected waves obtained when radio waves are emitted from a radio transmitter toward the rotating surface of the blade, assuming the blade is functioning correctly. [Figure 4] This figure shows an example of the delay profile of diffracted and reflected waves obtained when a blade breaks, when radio waves are emitted from a radio transmitter toward the rotating surface of the blade. [Figure 5] This figure shows an overview of the wind turbine blade inspection system according to the embodiment of this disclosure. [Figure 6] This is a block diagram showing the configuration of a wind turbine blade inspection system according to an embodiment of the present disclosure. [Figure 7] This flowchart shows the operation flow of the wind turbine blade inspection system according to the embodiment of this disclosure. [Figure 8] This figure shows an example of the time variation in the level of reflected waves received by a radio receiver when radio waves are emitted from a radio transmitter toward the rotating surface of a blade. [Figure 9] This flowchart shows the processing flow of the first specific example of received signal analysis processing. [Figure 10] This figure shows an example of the time variation in the phase difference between the reflected wave and the direct wave when a radio transmitter emits radio waves toward the rotating surface of a blade, as received by a radio receiver. [Figure 11] This flowchart shows the processing flow of the second specific example of received signal analysis processing. [Figure 12] This figure shows an example of a filter that extracts delayed waves. [Figure 13] This figure shows the configuration of a first modified example of a wind turbine blade inspection system according to the embodiment of this disclosure. [Figure 14]It is a diagram showing the configuration of a second modification of a blade inspection system for a wind power generation facility according to an embodiment of the present disclosure.

Embodiment for Carrying Out the Invention

[0013] 1. Outline of Blade Inspection Method Hereinafter, a system for inspecting a blade of a wind power generation facility according to an embodiment of the present disclosure and a method executed by the system will be described with reference to the drawings. Hereinafter, a system for inspecting a blade of a wind power generation facility will be referred to as a blade inspection system, and a method executed by the blade inspection system will be referred to as a blade inspection method.

[0014] First, the outline of the blade inspection method according to the embodiment of the present disclosure will be described with reference to FIG. 1. The blade inspection method according to the present embodiment is carried out during the operation of the wind power generation facility 4, that is, while the blade 6 of the wind power generation facility 4 is rotating. An unmanned aircraft is used in the blade inspection method according to the present embodiment. Specifically, the unmanned aircraft used are two drones 100A and 100B capable of hovering in the air. Hereinafter, when distinguishing between the two, the drone 100A will be denoted as the first drone, and the drone 100B will be denoted as the second drone.

[0015] The first drone 100A includes a radio transmitter 120A. The second drone 100B includes a radio receiver 120B. When inspecting the blade 6, the two drones 100A and 100B are flown near the wind power generation facility 4 and arranged at positions facing each other across the blade rotation surface 8 where the blade 6 rotates. Then, inspection radio waves are radiated from the inspection transmission antenna 104A of the radio transmitter 120A mounted on the first drone 100A toward the blade rotation surface 8. The radio waves radiated from the radio transmitter 120A pass through the blade rotation surface 8 and reach the inspection reception antenna 104B of the radio receiver 120B mounted on the second drone 100B.

[0016] When there is no obstruction between the first drone 100A and the second drone 100B, the radio waves radiated from the inspection transmitting antenna 104A reach the inspection receiving antenna 104B as direct waves. However, during the operation of the wind power generation equipment 4, the blades 6 rotate between the first drone 100A and the second drone 100B. Therefore, at the time when the blades 6 block the direct waves, some of the radiated radio waves are shielded by the blades 6. When the radio waves radiated from the radio transmitter 120A are shielded by the blades 6, diffracted waves are generated that bend around the back of the blades 6, and these are received by the radio receiver 120B along with the direct waves. Regarding the diffracted waves, as shown in Figure 1, the diffracted waves diffracted at the front edge in the direction of rotation of the blades 6 and the diffracted waves diffracted at the rear edge in the direction of rotation of the blades 6 are received separately by the radio receiver 120B. In addition, the pitch angle of the blades 6 is set so that they rotate due to the wind. Therefore, while the blade 6 is rotating, the radio waves emitted from the inspection transmitting antenna 104A of the first drone 100A are reflected off the surface of the blade 6 and received as reflected waves by the inspection receiving antenna 104B of the second drone.

[0017] Figure 2 shows an example of the time variation of the direct wave received by the radio receiver 120B when radio waves are emitted from the radio transmitter 120A toward the blade rotation surface 8. As shown in Figure 2, the reception level of the direct wave received by the radio receiver 120B decreases at a constant period. Since the decrease in the reception level occurs because the direct wave is shielded by the blade 6, the period of the decrease in the reception level corresponds to the rotation period of the blade 6.

[0018] While the direct wave reaches the receiver 120B from the radio transmitter 120A via the shortest distance, the diffracted and reflected waves reach the receiver 120B via bent paths. Therefore, the time at which the diffracted and reflected waves are received by the receiver 120B is delayed compared to the time at which the direct wave is received by the receiver 120B. Since the three blades 6 of the wind power generation equipment 4 are identical in shape, the delay time patterns of the diffracted and reflected waves relative to the direct wave are almost the same among the blades 6. Also, since there is no difference in the diffraction and reflection states of the radio waves among the blades 6, the reception levels of the direct wave, diffracted wave, and reflected wave received by the radio receiver 120B are also almost the same among the blades 6. As a result, if each blade 6 is functioning normally, when radio waves are radiated from the radio transmitter 120A toward the blade rotation surface 8, delay profiles of the diffracted and reflected waves as illustrated in Figure 3 should be obtained for all blades 6.

[0019] However, if there are abnormalities such as scratches, cracks, or deterioration due to defects on the surface of the blade 6, changes will occur in the diffraction state when radio waves are diffracted by the blade 6 and in the reflection state when radio waves are reflected by the surface of the blade 6. For example, scratches on the surface of the blade 6 may change the dielectric constant or change the direction of reflection of the reflected wave, thereby reducing the signal level of the reflected wave. Figure 4 shows an example of the delay profile of diffracted and reflected waves obtained when the blade 6 is damaged, when radio waves are radiated from the radio transmitter 120A toward the blade rotation surface 8. In this example, the reception level of the reflected wave received by the radio receiver 120B is reduced, but the phase difference of the reflected wave relative to the direct wave may also change. In addition, the reception level of the diffracted wave may decrease, or the phase difference of the diffracted wave relative to the direct wave may change. Furthermore, depending on the extent of the damage to the blade 6, a combination of these may occur.

[0020] As described above, damage or deterioration of the blade 6 changes the delay profile of the diffracted or reflected wave. The blade inspection method according to this embodiment focuses on this point. According to the blade inspection method according to this embodiment, first, with the first drone 100A and the second drone 100B facing each other across the blade rotation surface 8, radio waves are emitted from the radio transmitter 120A toward the blade rotation surface 8. Next, at least one of the reflected wave and the diffracted wave generated in the blade 6 by the radiation of radio waves from the radio transmitter 120A is received by the radio receiver 120B. Then, the presence or absence of an abnormality in the blade 6 is determined by analyzing the reflected wave or diffracted wave received by the radio receiver 120B. With this method, the blade 6 can be inspected without being affected by the rotation speed of the blade 6 or the weather.

[0021] 2. Configuration of the blade inspection system Next, a blade inspection system in which the above blade inspection method is implemented will be described. Figure 5 is a diagram showing an overview of the blade inspection system 2 according to this embodiment. The blade inspection system 2 according to this embodiment includes a first drone 100A and a second drone 100B, and an inspection control device 200 that controls them.

[0022] The first drone 100A comprises a drone body 110A having the basic structure of a drone, including rotors, motors, a speed controller, and a flight controller, and a radio transmitter 120A attached to the drone body 110A. An antenna 102A for drone control is attached to the drone body 110A. The first drone 100A also includes, internally, a processor 190A that is communicatively coupled to at least the radio transmitter 120A, and a memory 192A that is communicatively coupled to the processor 190A. Multiple executable instructions 194A are stored in the memory 192A.

[0023] The processor 190A may be a central processing unit (CPU), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or another processing unit. Alternatively, the processor 190A may be a combination of two or more CPUs, FPGAs, ASICs, or other processing units. When instruction 194A stored in memory 192A is executed, the processor 190A, which is a CPU, FPGA, ASIC, or another processing unit, is triggered to execute the function described later. Note that memory 192A may be a separate device from the processor 190A, or it may be built into the processor 190A.

[0024] The second drone 100B has a drone body 110B having the basic structure of a drone, such as rotors, motors, a speed controller, and a flight controller, and a radio receiver 120B attached to the drone body 110B. An antenna 102B for drone control is attached to the drone body 110B. The first drone 100B also has a processor 190B that is communicatively coupled to at least the radio receiver 120B, and a memory 192B that is communicatively coupled to the processor 190B. Multiple executable instructions 194B are stored in the memory 192B. The processor 190B may be a CPU, FPGA, ASIC, or another processing unit, or a combination of two or more CPUs, FPGAs, ASICs, or other processing units. The memory 192B may be a separate device from the processor 190B, or it may be built into the processor 190B.

[0025] The inspection and testing control device 200 is configured to control two drones 100A and 100B with a single unit, and to have the drones 100A and 100B perform inspections of the blades 6. The inspection and testing control device 200 is equipped with an antenna 202 for drone control. A signal line 10A for flight control and a signal line 20A for inspection and testing control are established between the antenna 202 of the inspection and testing control device 200 and the antenna 102A of the first drone 100A. A signal line 10B for flight control and a signal line 20B for inspection and testing control are established between the antenna 202 of the inspection and testing control device 200 and the antenna 102B of the second drone 100B. The inspection and testing control device 200 includes a processor 290 and a memory 292 that is communicatively coupled to the processor 290. Multiple executable instructions 294 are stored in the memory 292. The processor 290 may be a CPU, FPGA, ASIC, or another processing unit, or a combination of two or more CPUs, FPGAs, ASICs, or other processing units. The memory 292 may be a separate device from the processor 290, or it may be built into the processor 290.

[0026] Figure 6 is a block diagram showing the configuration of the blade inspection system 2. In Figure 6, the configuration of the drone 100 and the configuration of the inspection control device 200 are represented as blocks. The configuration of the drone 100 shown in Figure 6 is also the configuration of the first drone 100A and the second drone 100B. The first drone 100A and the second drone 100B have basically the same configuration, with the first drone 100A being used for transmission and the second drone 100B being used for reception.

[0027] The inspection and control device 200 comprises an inspection and control unit 210, a flight control unit 220, a wireless transceiver unit 230 for flight control, a radio wave transceiver unit 240, a wireless transceiver unit 250 for inspection and control, and an antenna 202 for drone control. The inspection and control unit 210 accepts operator input and also functions as an HMI that provides information to the operator. The inspection and control unit 210 is coupled to the flight control unit 220 and the radio wave transceiver unit 240. be.

[0028] The inspection and maintenance control unit 210 inputs piloting instructions from the operator to the flight control unit 220. The flight control unit 220 generates commands to fly the drone 100 according to the piloting instructions. The flight control commands generated by the flight control unit 220 are output from the drone control antenna 202 to the flight control signal line 10 by the flight control wireless transceiver unit 230. Information regarding the flight status of the drone 100, emitted from the drone 100, is input from the flight control signal line 10 to the flight control wireless transceiver unit 230 via the drone control antenna 202. The flight control unit 220 inputs the flight status information received by the flight control wireless transceiver unit 230 to the inspection and maintenance control unit 210. The inspection and maintenance control unit 210 stores the input flight status information in a storage device or displays it on a display device.

[0029] The inspection control unit 210 inputs an instruction from the operator to start the inspection to the radio wave transmission / reception control unit 240. Alternatively, the inspection control unit 210 itself determines whether to start the inspection based on information regarding the flight status of the drone 100 and inputs an instruction to start the inspection to the radio wave transmission / reception control unit 240. The radio wave transmission / reception control unit 240 generates an inspection command according to the instruction to start the inspection. The inspection command generated by the radio wave transmission / reception control unit 240 is output from the drone control antenna 202 to the inspection control signal line 20 by the wireless transmission / reception unit 250 for inspection and control. Inspection data transmitted from the drone 100 is input from the inspection control signal line 20 to the wireless transmission / reception unit 250 for inspection and control via the drone control antenna 202. The radio wave transmission / reception control unit 240 inputs the inspection data received by the wireless transmission / reception unit 250 for inspection and control to the inspection control unit 210. The inspection control unit 210 saves the input inspection data to a storage device or displays it on a display device.

[0030] In the above configuration of the inspection and control device 200, at least the inspection and control unit 210, the flight control unit 220, and the radio wave transmission and reception control unit 240 are implemented by a processor 290. Each of the inspection and control unit 210, the flight control unit 220, and the radio wave transmission and reception control unit 240 may be configured by a separate processor 290, or multiple of them may be configured by a single processor 290. For example, if the processor 290 is a CPU, the program including the instructions 294 may be provided via a network.

[0031] The drone 100 comprises a drone body 110, a drone control antenna 102, and a battery 130. Flight control commands issued from the survey and inspection control device 200 are input to the drone body 110 via the drone control antenna 102 from the flight control signal line 10. The flight controller constituting the drone body 110 controls the speed controllers of each motor based on the flight control commands. Power to operate the motors is supplied to the speed controllers from the battery 130. In addition, information regarding the flight status of the drone 100 issued from the flight controller is output from the drone control antenna 102 to the flight control signal line 10.

[0032] The drone 100 further comprises a wireless transceiver unit 140 for survey, inspection, and control, a processing unit 150, a transmission command unit 160, a radio wave transceiver 120, an inspection transceiver antenna 104, a received signal analysis processing unit 170, and a storage unit 180. The radio wave transceiver 120 includes a radio wave transmission unit 122 and a radio wave reception unit 124. Inspection commands issued from the survey, inspection, and control device 200 are input to the wireless transceiver unit 140 for survey, inspection, and control via the drone control antenna 102 from the survey, inspection, and control signal line 20. The wireless transceiver unit 140 for survey, inspection, and control inputs the received commands to the processing unit 150.

[0033] The processing performed by the processing unit 150 differs depending on whether the drone 100 is operating as the first drone 100A or the second drone 100B. When the drone 100 is operating as the first drone 100A, the processing unit 150 receives an inspection command and activates the transmission command unit 160. The activated transmission command unit 160 issues a radio wave transmission command to the radio wave transmission unit 122. The radio wave transmission unit 122 receives the radio wave transmission command and emits radio waves from the inspection transceiver antenna 104. In this case, the radio wave transceiver 120 functions as the radio wave transmitter 120A, and the inspection transceiver antenna 104 functions as the inspection transmission antenna 104A.

[0034] When drone 100 is operated as the second drone 100B, the processing unit 150 receives an inspection command and activates the radio wave receiving unit 124 and the received signal analysis processing unit 170. The radio wave receiving unit 124 receives radio waves input to the inspection transmitting / receiving antenna 104. When inspecting the blade 6, the radio waves received by the radio wave receiving unit 124 include direct waves, diffracted waves, and reflected waves. In this case, the radio wave transceiver 120 functions as a radio wave receiver 120B, and the inspection transmitting / receiving antenna 104 functions as an inspection receiving antenna 104B. The received signal analysis processing unit 170 analyzes the received radio waves and stores the analysis results in the storage unit 180. The storage unit 180 is, for example, a storage device such as flash memory or a hard disk. The specific details of the received signal analysis processing by the received signal analysis processing unit 170 will be described later, but the presence or absence of abnormalities in the blade 6 is determined from the analysis results. The analysis results stored in the memory unit 180 are output from the wireless transceiver unit 140 for survey, inspection, and control to the flight control signal line 10 via the drone control antenna 102.

[0035] In the above configuration of the drone 100, at least the processing unit 150, the transmission command unit 160, and the received signal analysis processing unit 170 are implemented by a processor. Each of the processing unit 150, the transmission command unit 160, and the received signal analysis processing unit 170 may be configured by a separate processor, or multiple of them may be configured by a single processor. When the drone 100 is operated as the first drone 100A, the processing unit 150 and the transmission command unit 160 are each configured by separate processors 190A, or one processor 190A constitutes both the processing unit 150 and the transmission command unit 160. When the drone 100 is operated as the second drone 100B, the processing unit 150 and the received signal analysis processing unit 170 are each configured by separate processors 190B, or one processor 190B constitutes both the processing unit 150 and the received signal analysis processing unit 170. For example, if each processor 190A, 190B is a CPU, the program including instruction 194A and the program including instruction 194B may be provided via a network.

[0036] 3. Operation of the blade inspection system Next, the operation of the blade inspection system 2 configured as described above will be explained using a flowchart. Figure 7 shows both a flowchart illustrating the operation flow of the inspection control device 200 and a flowchart illustrating the operation flow of the drone 100, in particular the radio wave transceiver 120.

[0037] According to the operation flow of the inspection control device 200, first, in step S201, the position information of the two drones 100A and 100B is confirmed. In step S202, a decision is made on whether to start blade inspection based on the position information confirmed in step S201. Specifically, after it is confirmed that the first drone 100A and the second drone 100B are facing each other across the blade rotation surface 8, it is decided to start blade inspection. This decision may be made by the inspection control unit 210, or it may be accepted as input from the operator. Whether the first drone 100A and the second drone 100B are facing each other across the blade rotation surface 8 can be determined from the reception status of radio waves emitted from the first drone 100A by the second drone 100B. In addition, if at least one of the two drones 100A and 100B is equipped with a camera, the positional relationship between the two with respect to the blade rotation surface 8 can be confirmed from the camera image.

[0038] If it is determined in step S202 to start blade inspection, an inspection command is sent from the inspection control device 200 to the drone 100 in step S203. The inspection command is sent simultaneously to both the first drone 100A and the second drone 100B.

[0039] Here, we will explain the operation of each drone 100A and 100B after receiving an inspection command. The two drones 100A and 100B fly to positions opposite each other with the blade rotation surface 8 in between, and then hover while waiting for the inspection to begin. In other words, as shown in the operation flow of drone 100, first, in step S101, each drone 100A and 100B enters a waiting state for the inspection to begin. Then, in step S102, it is determined whether an inspection command has been received from the survey and inspection control device 200. Until an inspection command is received, each drone 100A and 100B maintains a waiting state.

[0040] If an inspection command is received in step S102, it is determined in step S103 whether to perform a transmission process or a reception process. This determination is made in the processing unit 150. In the case of the first drone 100A, which uses the radio transceiver 120 to function as a radio transmitter 120A, the operation flow proceeds to step S111 in order to perform a transmission process. The operation flow from step S111 to step S114 is the operation flow of the first drone 100A.

[0041] In step S111, the radio transmitter 120A of the first drone 100A starts transmitting radio waves. In step S112, it is determined whether a termination command has been received from the inspection control device 200. The termination command is a command to drones 100A and 100B to end the blade inspection. Until a termination command is received, the radio transmitter 120A continues transmitting radio waves in step S113.

[0042] In the case of the second drone 100B, which uses the radio transceiver 120 as a radio receiver 120B, the operation flow proceeds from step S103 to step S121 in order to perform reception processing. The operation flow from step S121 to step S125 is the operation flow of the second drone 100B.

[0043] In step S121, the radio receiver 120B of the second drone 100B starts receiving radio waves. In step S122, analysis processing is performed on the radio waves received by the radio receiver 120B. Details of the received signal analysis processing performed in step S122 will be described later. Next, in step S123, the analysis results from the received signal analysis processing, that is, inspection data showing the results of the blade inspection, are transmitted to the survey and inspection control device 200. However, instead of transmitting the analysis results in step S123, the analysis results may be stored in the storage unit 180. In step S124, it is determined whether a termination command has been received from the survey and inspection control device 200. Steps S122 and S123 are repeated until a termination command is received.

[0044] Returning to the operation flow of the inspection control device 200, after sending inspection commands to drones 100A and 100B, step S204 determines whether to terminate the blade inspection. This determination may be made by the inspection control unit 210, or it may be accepted as input from the operator. For example, upon receiving inspection data indicating the results of the blade inspection from the second drone 100B, the inspection control unit 210 may automatically terminate the blade inspection, or the operator may terminate the blade inspection after confirming the inspection data. In addition, the blade inspection may be forcibly terminated before inspection data is obtained, based on the operator's judgment.

[0045] If the blade inspection is completed, the next step S205 determines whether to save the inspection data transmitted from the second drone 100B. If the determination in step S205 is affirmative, in step S206 the inspection data is saved to the storage of the inspection control device 200. Whether or not to save the inspection data can be decided arbitrarily. For example, if, as a result of reviewing the inspection data, it is determined that there is clearly no abnormality in the blade 6, the inspection data may not be saved. On the other hand, if it is determined that there is a possibility of an abnormality in the blade 6, the inspection data may be saved.

[0046] In step S207, after deciding whether or not to save the inspection data, the inspection control device 200 sends a termination command to both the first drone 100A and the second drone 100B. Then, in step S208, the blade inspection is terminated upon receiving the termination command.

[0047] Upon receiving the termination command transmitted from the inspection control device 200 by the first drone 100A, the determination in step S112 changes from negative to positive. As a result, in step S114, the transmission of radio waves by the radio transmitter 120A is terminated.

[0048] Furthermore, upon receiving the termination command transmitted from the survey and inspection control device 200 by the second drone 100B, the determination in step S124 changes from negative to positive. As a result, in step S125, the reception of radio waves by the radio receiver 120B and the analysis processing by the received signal analysis processing unit 170 are terminated.

[0049] 4. Received signal analysis processing 4-1. First Specific Example Next, we will specifically describe the received signal analysis processing performed by the received signal analysis processing unit 170 when drone 100 functions as the second drone 100B. The received signal analysis processing is an analysis process performed on reflected waves or diffracted waves to determine whether or not there is an abnormality in the blade 6 from the radio waves received by the radio wave receiver 120B. Here, we will describe the analysis processing for reflected waves, in particular the analysis processing based on the reception level of the reflected waves.

[0050] Figure 8 shows an example of the time variation in the level of the reflected wave received by the radio receiver 120B when radio waves are emitted from the radio transmitter 120A toward the blade rotation surface 8. If the second blade of the three blades is damaged, the reflected wave from the second blade will show a different profile from the reflected waves from the first and third blades. In the example shown in Figure 8, a large fluctuation occurs only in the reception level of the second blade. In the first specific example of the received signal analysis process, the presence or absence of a malfunction in the blade 6 is determined by detecting such abnormal fluctuations in the reception level.

[0051] Figure 9 is a flowchart showing the processing flow of a first specific example of the received signal analysis process. First, in step S301, the delay profile of the radio waves received by the radio wave receiver 120B is measured. In step S302, the counter τ for determining the end of the measurement interval shown in Figure 8 is initialized.

[0052] In step S303, the reflected wave is extracted from the delay profile measured in step S301. A specific example of the method for extracting the reflected wave will be described later. Next, in step S304, it is determined whether the received level of the extracted reflected wave has become greater than a threshold. The threshold used in step S304 is a threshold for detecting the rising edge of the reflected wave. Steps S303 and S304 are repeated until the received level of the reflected wave becomes greater than the threshold. The received level of the reflected wave becoming greater than the threshold signifies the start of the measurement interval.

[0053] If the received level of the reflected wave exceeds the threshold, the loop of steps S303 and S304 is exited and the processing flow proceeds to step S305. In step S305, data on the received level of the reflected wave over time is accumulated. Next, in step S306, it is determined whether the extracted received level of the reflected wave remains above the threshold. The threshold used in step S306 is a threshold for detecting the falling edge of the reflected wave. The value of this threshold may be the same as the threshold used in step S304. Steps S305 and S306 are repeated until the received level of the reflected wave falls below the threshold.

[0054] As shown in Figure 8, there are two cases in which the reflected wave reception level falls below the threshold: when the blade passes and the measurement section ends, and when the reflected wave reception level fluctuates due to blade damage. In the former case, the reception level remains below the threshold, whereas in the latter case, the decrease in the reception level is temporary. Therefore, to distinguish between the two, the elapsed time since the reflected wave reception level fell below the threshold is measured. The parameter used to measure the elapsed time is the counter initialized in step S302.

[0055] If the reflected wave reception level falls below a threshold in step S306, it is determined in step S307 whether the counter τ has exceeded a predetermined time T. The predetermined time T is the time at which it can be determined that the measurement interval has ended if the time during which the reflected wave reception level remains below the threshold is longer than that time. The predetermined time T can be set based on the rotation speed of the blade 6 and the width of the blade 6. If the counter τ has not exceeded the predetermined time T, a waiting time of Δt is given in step S308. In step S309, the counter τ is updated by adding the waiting time Δt to the counter τ.

[0056] Steps S305 to S309 are repeated until the counter τ exceeds a predetermined time T, as determined in step S307. When the counter τ exceeds the predetermined time T, it is determined that the measurement section of the reflected wave has ended, and the process flow exits the loop of steps S305 to S309 and proceeds to step S310. In step S310, it is determined whether the fluctuation of the received level data accumulated during the measurement section is large. Specifically, it is determined whether the variance or standard deviation of the accumulated received level data is greater than a predetermined reference value.

[0057] Fluctuations in the received level data accumulated during the measurement interval indicate whether or not there is an abnormality in the blade corresponding to that measurement interval. If the fluctuation in the received level data is large, it is determined in step S311 that there is damage to the blade corresponding to the measurement interval. If the fluctuation in the received level data is not large, it is determined in step S312 that there is no abnormality in the blade corresponding to the measurement interval.

[0058] The first specific example of the received signal analysis process having the above processing flow can also be applied to analysis processing based on the received level of diffracted waves.

[0059] 4-2. Second Specific Example Next, a second specific example of the received signal analysis process performed by the received signal analysis processing unit 170 will be described. Here, the analysis process for reflected waves, in particular, the analysis process based on the phase difference of the reflected wave compared to the direct wave, will be described.

[0060] Figure 10 shows an example of the time variation of the phase difference between the reflected wave and the direct wave when radio waves are radiated from the radio transmitter 120A toward the blade rotation surface 8, and received by the radio receiver 120B. If the second blade of the three blades is damaged, the reflected wave from the second blade will show a different profile from the reflected waves from the first and third blades. In the example shown in Figure 10, a large variation in the phase difference between the reflected wave and the direct wave occurs only in the second blade. In the second specific example of the received signal analysis process, the presence or absence of a defect in blade 6 is determined by detecting an abnormal variation in the phase difference between the reflected wave and the direct wave.

[0061] Figure 11 is a flowchart showing the processing flow of a second specific example of the received signal analysis process. First, in step S401, the delay profile of the radio wave received by the radio wave receiver 120B is measured. In step S402, the reflected wave is extracted from the delay profile measured in step S401. A specific example of the method for extracting the reflected wave will be described later. Next, in step S403, it is determined whether the received level of the extracted reflected wave has become greater than a threshold. The threshold used in step S403 is a threshold for detecting the rising edge of the reflected wave. Steps S402 and S403 are repeated until the received level of the reflected wave becomes greater than the threshold. The received level of the reflected wave becoming greater than the threshold signifies the start of the measurement interval.

[0062] If the received level of the reflected wave exceeds the threshold, the processing flow exits the loop of steps S402 and S403 and proceeds to step S404. In step S404, the phase difference of the reflected wave relative to the direct wave is measured. In step S405, the phase difference data measured in step S404 is accumulated. Next, in step S406, it is determined whether the state in which the received level of the extracted reflected wave remains above the threshold is maintained. The threshold used in step S406 is a threshold for detecting the falling edge of the reflected wave. The value of this threshold may be the same as the threshold used in step S403. Steps S404 to S406 are repeated until the received level of the reflected wave falls below the threshold.

[0063] If the reflected wave reception level falls below a threshold in step S406, it is determined that the measurement section for the reflected wave has ended, and the processing flow exits the loop of steps S404 to S406 and proceeds to step S407. In step S407, it is determined whether the fluctuations in the phase difference data accumulated during the measurement section are large. Specifically, it is determined whether the variance or standard deviation of the accumulated phase difference data is greater than a predetermined reference value.

[0064] Fluctuations in the phase difference data accumulated during the measurement interval indicate whether or not there is an abnormality in the blade corresponding to that measurement interval. If the fluctuation in the received level data is large, it is determined in step S408 that there is damage to the blade corresponding to the measurement interval. If the fluctuation in the received level data is not large, it is determined in step S409 that there is no abnormality in the blade corresponding to the measurement interval.

[0065] The second specific example of the received signal analysis process having the above processing flow can also be applied to analysis processing based on the phase difference of the diffracted wave relative to the direct wave. Furthermore, it is possible to determine the presence or absence of blade abnormalities by using the first and second specific examples of the received signal analysis process in combination.

[0066] 5. Filter for extracting delayed waves As a means of extracting diffracted and reflected waves from radio waves received by the radio wave receiver 120B, for example, a transversal filter as shown in Figure 12 can be used. Figure 12 depicts a filter configured to extract a first wave, a filter configured to extract a second wave, a filter configured to extract a third wave, and a filter configured to extract a fourth wave.

[0067] Figure 12 also shows example delay profiles for the first to fourth waves. The reception levels h1 for the first wave, h2 for the second wave, h3 for the third wave, and h4 for the fourth wave shown in the delay profiles are all measured values ​​under normal conditions. The delay times τ1 for the second wave relative to the first wave, τ2 for the third wave relative to the second wave, and τ3 for the fourth wave relative to the third wave, also shown in the delay profiles, are all measured values ​​under normal conditions. Each filter is created using these values.

[0068] 6. Variations of the blade inspection system 6-1. First Variation Finally, a modified example of the blade inspection system according to this embodiment will be described with reference to the figures. In the figures showing the modified example, elements common to the blade inspection system 2 are denoted by the same reference numerals.

[0069] Figure 13 shows the configuration of a first modified example of the blade inspection system according to this embodiment. The first modified blade inspection system 2-1 includes a first drone 100A equipped with a radio transmitter 120A, a second drone 100B equipped with a radio receiver 120B, a survey and inspection control device 200, and an analysis computer 300. The analysis computer 300 includes a processor 302 and a memory 304 that is communicatively coupled to the processor 302. Multiple executable instructions 306 are stored in the memory 304. The analysis computer 300 is connected to the survey and inspection control device 200.

[0070] In the first modified blade inspection system 2-1, the second drone 100B does not have a received signal analysis processing unit. Therefore, the received signal analysis processing for determining whether or not there is an abnormality in the blade 6 is not performed by the second drone 100B. The second drone 100B transmits the received data, including direct waves, diffracted waves, and reflected waves received by the radio receiver 120B, to the inspection control device 200.

[0071] The inspection control device 200 transfers the received data transmitted from the second drone 100B to the analysis computer 300. In the analysis computer 300, at least a portion of the multiple instructions 306 are executed by the processor 302, so that the processor 302 functions as a received signal analysis processing unit 310. In other words, in the first modified blade inspection system 2-1, the received signal analysis processing is performed by the analysis computer 300.

[0072] 6-2. Second Variation Figure 14 shows the configuration of a second modified example of the blade inspection system according to this embodiment. The second modified example, blade inspection system 2-2, includes a first drone 100A equipped with a radio transmitter 120A, a second drone 100B equipped with a radio receiver 120B, an inspection control device 200, and an analysis computer 300. The analysis computer 300 includes a processor 302 and a memory 304 that is communicatively coupled to the processor 302. Multiple executable instructions 306 are stored in the memory 304.

[0073] In the second modified blade inspection system 2-2, the second drone 100B does not have a received signal analysis processing unit. Therefore, the received signal analysis processing to determine whether or not there is an abnormality in the blade 6 is not performed by the second drone 100B. The second drone 100B stores the received data, including the direct wave, diffracted wave, and reflected wave received by the radio receiver 120B, in storage 196B.

[0074] The received data stored in the storage 196B of the second drone 100B can be transferred from the storage 196B to the analysis computer 300 by connecting the second drone 100B to the analysis computer 300. Alternatively, if the storage 196B is, for example, a memory card, the received data can be transferred to the analysis computer 300 by moving the memory card from the second drone 100B to the analysis computer 300. In the analysis computer 300, at least a portion of the multiple instructions 306 are executed by the processor 302, causing the processor 302 to function as a received signal analysis processing unit 310. In other words, in the second modified blade inspection system 2-2, the received signal analysis processing is performed by the analysis computer 300.

[0075] 7. Other In the embodiment described above, radio waves are used for blade inspection, but electromagnetic waves can be used for blade inspection as long as reflected or diffracted waves can be obtained.

[0076] In the above embodiment, two drones 100A and 100B are controlled by one survey and inspection control device 200. However, the survey and inspection control device that controls the first drone 100A and the survey and inspection control device that controls the second drone 100B may be different devices. [Explanation of symbols]

[0077] 2, 2-1, 2-2 Blade Inspection System 4. Wind power generation facilities 6 blades 8 Blade rotation surface 100 Drones (Unmanned Aerial Vehicles) 100A First Drone (First Unmanned Aerial Vehicle) 100B Second Drone (Second Unmanned Aerial Vehicle) 120 Radio Transceivers 120A radio transmitter 120B radio receiver 170, 310 Received signal analysis processing unit 190A, 190B, 290, 302 processors 192A, 192B, 292, 304 memory Instructions 194A, 194B, 294, 306 200 Inspection and Control Device 300 computers for analysis

Claims

1. A system for inspecting the blades of wind turbines, The electromagnetic wave transmitter mounted on the first unmanned aerial vehicle, The electromagnetic wave receiver mounted on the second unmanned aerial vehicle, At least one processor is communicatively coupled to the transmitter and the receiver, The system comprises a memory that stores multiple executable instructions and is communicably coupled to at least one processor, The plurality of instructions are provided to at least one processor, The first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotating surface of the blade, and the transmitter emits electromagnetic waves toward the rotating surface. The receiver receives at least one of the reflected waves and diffracted waves generated in the blade by the radiation of electromagnetic waves from the transmitter. The receiver is configured to perform the following actions: determine whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiver. Determining whether or not there is an abnormality in the blade by the analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the reception level of the diffracted waves received by the receiver. A system characterized by the following features.

2. A system for inspecting the blades of a wind turbine, The electromagnetic wave transmitter mounted on the first unmanned aerial vehicle, The electromagnetic wave receiver mounted on the second unmanned aerial vehicle, At least one processor is communicatively coupled to the transmitter and the receiver, The system comprises a memory that stores multiple executable instructions and is communicably coupled to at least one processor, The plurality of instructions are provided to at least one processor, The first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotating surface of the blade, and the transmitter emits electromagnetic waves toward the rotating surface. The receiver receives at least one of the reflected waves and diffracted waves generated in the blade by the radiation of electromagnetic waves from the transmitter. The receiver is configured to perform the following actions: determine whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiver. Determining whether or not there is an abnormality in the blade by the aforementioned analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the phase difference between the reflected wave or diffracted wave received by the receiver and the direct wave. A system characterized by the following features.

3. A system for inspecting the blades of a wind turbine, The electromagnetic wave transmitter mounted on the first unmanned aerial vehicle, The electromagnetic wave receiver mounted on the second unmanned aerial vehicle, At least one processor is communicatively coupled to the transmitter and the receiver, The system comprises a memory that stores multiple executable instructions and is communicably coupled to at least one processor, The plurality of instructions are provided to at least one processor, The first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotating surface of the blade, and the transmitter emits electromagnetic waves toward the rotating surface. The receiver receives at least one of the reflected waves and diffracted waves generated in the blade by the radiation of electromagnetic waves from the transmitter. The receiver is configured to perform the following actions: determine whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiver. The analysis process includes extracting at least one of the reflected wave and the diffracted wave from a received wave that includes the reflected wave and the diffracted wave, and the direct wave, by using a filter based on a delay profile. A system characterized by the following features.

4. A method for inspecting the blades of a wind turbine, The first unmanned aerial vehicle equipped with an electromagnetic wave transmitter is to be stationed around the rotating surface of the blade, A second unmanned aerial vehicle equipped with an electromagnetic wave receiver is to be stationed around the rotating surface, The first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotating surface, and the transmitter emits electromagnetic waves toward the rotating surface. The receiver receives at least one of the reflected waves and diffracted waves generated in the blade by the radiation of electromagnetic waves from the transmitter. This includes determining whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiver, Determining whether or not there is an abnormality in the blade by the analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the reception level of the diffracted waves received by the receiver. A method characterized by the following:

5. A method for inspecting the blades of a wind turbine, The first unmanned aerial vehicle equipped with an electromagnetic wave transmitter is to be stationed around the rotating surface of the blade, A second unmanned aerial vehicle equipped with an electromagnetic wave receiver is to be stationed around the rotating surface, The first unmanned aerial vehicle and the second unmanned aerial vehicle are facing each other across the rotating surface, and the transmitter emits electromagnetic waves toward the rotating surface. The receiver receives at least one of the reflected waves and diffracted waves generated in the blade by the radiation of electromagnetic waves from the transmitter. This includes determining whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiver, Determining whether or not there is an abnormality in the blade by the aforementioned analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the phase difference between the reflected wave or diffracted wave received by the receiver and the direct wave. A method characterized by the following:

6. A device for inspecting the blades of a wind turbine, Antenna and, When the antenna is facing an electromagnetic wave transmitter across the rotating surface of the blade, the receiving unit is configured to receive at least one of the reflected waves and diffracted waves generated on the blade by the radiation of electromagnetic waves from the transmitter using the antenna, The system includes an analysis processing unit configured to determine whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiving unit, Determining whether or not there is an abnormality in the blade by the analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the reception level of the diffracted waves received by the receiving unit. A device characterized by the following features.

7. A device for inspecting the blades of a wind turbine, Antenna and, When the antenna is facing an electromagnetic wave transmitter across the rotating surface of the blade, the receiving unit is configured to receive at least one of the reflected waves and diffracted waves generated on the blade by the radiation of electromagnetic waves from the transmitter using the antenna, The system includes an analysis processing unit configured to determine whether or not there is an abnormality in the blade by analyzing the reflected or diffracted wave received by the receiving unit, Determining whether or not there is an abnormality in the blade by the aforementioned analysis process includes distinguishing between abnormal blades and normal blades based on the fluctuation state of the phase difference between the reflected wave or diffracted wave received by the receiving unit and the direct wave. A device characterized by the following features.

Images