Patent Description:
Patent Document <NUM> discloses a state monitoring system for a wind turbine power generating apparatus for accurately estimating the damage state of wind turbine blades due to a lightning strike. In this state monitoring system, the damage state of wind turbine blades is estimated based on a lightning parameter indicating the severity of the lightning strike. <CIT> describes systems and methods for detecting lightning strikes on wind turbines. <CIT> describes a device for detecting lightning strike damage of a blade based on noise.

When lightning strikes a wind turbine blade on a wind turbine generator, the damage state of the wind turbine blade can be checked by inspecting the wind turbine blade. However, it is undesirable in terms of labor and cost to dispatch a person for inspection regardless of the magnitude of the damage risk of the lightning strike. It is desirable to perform automatic inspection of the wind turbine blade according to the magnitude of the damage risk of the lightning strike. In this regard, Patent Document <NUM> does not disclose a configuration for judging the necessity of automatic inspection of the wind turbine blade according to the magnitude of the damage risk of the wind turbine blade.

In view of the above, an object of the present disclosure is to provide a wind turbine monitoring device, a wind turbine system, and a wind turbine monitoring method whereby it is possible to judge whether it is necessary to automatically inspect the wind turbine blade according to the magnitude of the damage risk of the wind turbine blade.

To accomplish the above object, there is provided a wind turbine monitoring device according to claim <NUM>.

Further, to accomplish the above object, there is provided a wind turbine monitoring method according to claim <NUM>.

According to the present disclosure, there is provided a wind turbine monitoring device, a wind turbine system, and a wind turbine monitoring method whereby it is possible to judge whether it is necessary to automatically inspect the wind turbine blade according to the magnitude of the damage risk of the wind turbine blade.

Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.

<FIG> is a schematic side view of a wind turbine <NUM> to be monitored by a wind turbine monitoring device according to an embodiment.

The wind turbine <NUM> includes a tower <NUM> installed on a foundation <NUM>, a nacelle <NUM> disposed on the upper end of the tower <NUM>, a rotor <NUM>, and a generator <NUM> driven by the rotor <NUM>. The rotor <NUM> includes a rotor head (hub) <NUM> rotatably attached to the nacelle <NUM>, and at least one wind turbine blade (blade) <NUM> attached to the rotor head <NUM>. In an embodiment, the wind turbine <NUM> has three wind turbine blades <NUM>.

When the rotor <NUM> is rotated by wind power, the generator <NUM> generates electric power, and the electric power is supplied to a power grid connected to the generator <NUM>. The wind turbine <NUM> can be installed both onshore and offshore.

<FIG> is a diagram schematically showing a surrounding structure of the rotor <NUM>.

In some embodiments, each wind turbine blade <NUM> of the wind turbine <NUM> includes a hollow blade body <NUM> composed of, for example, a glass fiber reinforced plastic (GFRP) or carbon fiber reinforced plastic (CFRP) and a coil or (mesh) metal layer <NUM> formed on the surface of the blade body <NUM>. In other cases, the wind turbine blade <NUM> includes the hollow blade body <NUM> and a conductor inside the blade body <NUM>. This figure shows the former. The metal layer <NUM> extends from the blade tip to the blade root of each wind turbine blade <NUM>, and is electrically connected to a conductive electric discharge member <NUM> fitted at the blade root.

The electric discharge member <NUM> is electrically connected to a power receiving part <NUM> disposed on the nacelle <NUM> via a spoke-like conductive material <NUM> extending radially from the nacelle <NUM>, and is electrically connected to the nacelle <NUM>. The conductive portion of the nacelle <NUM> is electrically connected to the conductive portion of the tower <NUM>. One end of the conductive material <NUM> forms a contact point <NUM> which is slidable on the outer peripheral surface of the electric discharge member <NUM> when the wind turbine blade <NUM> changes the pitch angle in the direction A. The other end of the conductive material <NUM> forms a contact point <NUM> which is slidable on the power receiving part <NUM> when the rotor <NUM> rotates in the direction B. Thus, the metal layer <NUM>, the electric discharge member <NUM>, the nacelle <NUM>, and the tower <NUM> constitute a current path (grounding line) <NUM> (see <FIG>) extending from the tip of the wind turbine blade <NUM> to the lower end of the tower <NUM>, and the metal layer <NUM> functions as a down-conductor. Each wind turbine blade <NUM> may have a conductive wire extending inside the wind turbine blade <NUM> as a down-conductor. The current path <NUM> constitutes a lightning protection system (LPS) of the wind turbine blade <NUM>.

<FIG> is a diagram showing a hardware configuration of a wind turbine monitoring device <NUM> for monitoring the wind turbine <NUM>.

The wind turbine monitoring device <NUM> is provided by a computer including a central processing unit (CPU) <NUM>, a random access memory (RAM) <NUM>, a read only memory (ROM) <NUM>, a hard disk drive (HDD) <NUM>, an input I/F <NUM>, and an output I/F <NUM>, which are connected via a bus <NUM>. The hardware configuration of the wind turbine monitoring device <NUM> is limited thereto, and may be configured by a combination of a control circuit and a storage device. The wind turbine monitoring device <NUM> is provided by executing a program that realizes each function of the wind turbine monitoring device <NUM> by the computer. The function of each part of the wind turbine monitoring device <NUM> described below is realized by, for instance, loading a program stored in the ROM <NUM> into the RAM <NUM> and executing the program by the CPU <NUM>, and reading and writing data in the RAM <NUM> or the ROM <NUM>. Further, with an arithmetic device specialized for image processing such as graphics processing unit (GPU), image data can be more efficiently processed.

<FIG> is a block diagram for describing a functional configuration of the wind turbine monitoring device <NUM>. The wind turbine monitoring device <NUM> is arranged, for instance, inside the nacelle <NUM>, and the wind turbine <NUM> and the wind turbine monitoring device <NUM> constitutes a wind turbine system.

As shown in <FIG>, a current sensor <NUM> is attached to a portion of the current path <NUM> for example between the electric discharge member <NUM> and the nacelle <NUM> as a lightning sensor for detecting a lightning strike on the wind turbine blade <NUM>. In an embodiment, three current sensors <NUM> are attached to three parallel portions of respective current paths <NUM> of three wind turbine blades <NUM>. More specifically, one current sensor <NUM> is attached to each of the three conductive materials <NUM>. That is, the current sensor <NUM> is disposed on each wind turbine blade <NUM> to detect a lightning current flowing through the wind turbine blade <NUM>. The current sensor <NUM> is, for example, a Rogowski coil or a current transducer.

The wind turbine monitoring device <NUM> includes a lightning parameter acquisition part <NUM>, a lightning level determination part <NUM>, and an inspection control part <NUM>.

The lightning parameter acquisition part <NUM> is configured to acquire a plurality of lightning parameters based on the output of the current sensor <NUM>. In the present embodiment, the lightning parameter acquisition part <NUM> acquires a plurality of lightning parameters for example including a peak value of lightning current flowing through the wind turbine blade <NUM> due to the lightning strike, a specific energy of the lightning strike obtained by integrating the square of the lightning current over the duration of the lightning strike, and/or an electric charge of the lightning strike obtained by integrating the lightning current over the duration of the lightning strike, based on the output of the current sensor <NUM>. Hereinafter, the term "peak value of current" means the peak value of the lightning current (maximum value of lightning current) acquired by the lightning parameter acquisition part <NUM>, the term "specific energy" means the specific energy of the lightning strike acquired by the lightning parameter acquisition part <NUM>, and the term "electric charge" means the electric charge of the lightning strike acquired by the lightning parameter acquisition part <NUM>.

The lightning level determination part <NUM> determines a level of the lightning strike detected by the current sensor <NUM> from a plurality of lightning levels Q1 to Q4, based on the plurality of lightning parameters (peak value of lightning current, specific energy, and electric charge) acquired by the lightning parameter acquisition part <NUM>.

In the present embodiment, the plurality of lightning levels includes four levels: Q1 (first level), Q2 (second level), Q3 (third level) and Q4 (fourth level) in order of severity. Specifically, among the four lightning levels Q1 to Q4, Q1 is the least severe, Q2 is more severe than Q1, Q3 is more severe than Q2, and Q4 is more severe than Q3 and the most severe. Other embodiments of the invention may have fewer or more levels.

An example of a method for determining the level of the lightning strike by the lightning level determination part <NUM> will now be described.

First, the lightning level determination part <NUM> determines whether the level of the lightning strike detected by the current sensor <NUM> is Q1. Specifically, if all of the following conditions <NUM>, <NUM>, and <NUM> are satisfied, it is determined that the level of the lightning strike is Q1.

Condition <NUM>: peak value of lightning current is greater than <NUM> and equal to or less than threshold I1.

Condition <NUM>: specific energy is greater than <NUM> and equal to or less than threshold E1.

Condition <NUM>: electric charge is greater than <NUM> and equal to or less than threshold C1.

The thresholds I1, E1, and C1 may be for example, but is not limited to, <NUM> (kA), <NUM> (MJ/ohm), and <NUM> (C), respectively.

If the level of the lightning strike is not Q1, the lightning level determination part <NUM> determines whether the level of the lightning strike is Q4. Specifically, if at least one of the following conditions <NUM>, <NUM>, and <NUM> is satisfied, it is determined that the level of the lightning strike is Q4.

Condition <NUM>: peak value of lightning current is greater than threshold I3.

Condition <NUM>: specific energy is greater than threshold E3.

Condition <NUM>: electric charge is greater than threshold C3.

The thresholds I3, E3, and C3 are greater than the thresholds I1, E1, and C1, respectively. The thresholds I3, E3, and C3 may be for example, but is not limited to, <NUM> (kA), <NUM> (MJ/ohm), and <NUM> (C), respectively.

If the level of the lightning strike is neither Q1 nor Q4, and if at least one of the following conditions <NUM>, <NUM>, and <NUM> is satisfied, the lightning level determination part <NUM> determines that the level of the lightning strike is Q3.

Condition <NUM>: peak value of lightning current is greater than threshold I2.

Condition <NUM>: specific energy is greater than threshold E2.

Condition <NUM>: electric charge is greater than threshold C2.

The thresholds I2, E2, and C2 are greater than the thresholds I1, E1, and C1, respectively. Further, the thresholds I2, E2, and C2 are less than the thresholds I3, E3, and C3, respectively. The thresholds I2, E2, and C2 may be for example, but is not limited to, <NUM> (kA), <NUM> (MJ/ohm), and <NUM> (C), respectively.

If the level of the lightning strike is neither Q1, Q3 nor Q4, since at least one of the following conditions <NUM>, <NUM>, and <NUM> is satisfied, it is determined that the level of the lightning strike is Q2.

Condition <NUM>: peak value of lightning current is greater than threshold I1.

Condition <NUM>: specific energy is greater than threshold E1.

Condition <NUM>: electric charge is greater than threshold C1.

The inspection control part <NUM> is configured to judge whether it is necessary to automatically inspect the wind turbine blade <NUM> by at least one inspection unit <NUM> for automatically inspecting the damage state of the wind turbine blade <NUM>, according the level Q1 to Q4 of the lightning strike determined by the lightning level determination part <NUM>. Further, the inspection control part <NUM> is configured to judge whether it is necessary to inspect the wind turbine blade <NUM> by at least one inspection unit <NUM> for inspecting the damage state of the wind turbine blade <NUM>, according the level Q1 to Q4 of the lightning strike determined by the lightning level determination part <NUM>. The inspection unit <NUM> and the inspection unit <NUM> differ in the manner of inspecting the wind turbine blade <NUM>. Herein, the "automatic inspection" means that the inspection unit <NUM> automatically inspects the wind turbine blade <NUM> without any manual operation.

The at least one inspection unit <NUM> is an inspection unit which enables simple automatic inspection of the wind turbine blade <NUM>, and includes at least one of an imaging device 40a, a microphone 40b, or an evaluation part 40c, as shown in <FIG>. The at least one inspection unit <NUM> is an inspection unit which enables remote inspection of the wind turbine blade <NUM> without sending a person to the wind turbine <NUM>, and includes at least one of a load sensor 41a, a drone 41b, an evaluation part 41c, an electrical resistance sensor 41d, an acceleration sensor 41e, an optical sensor 41f, a deflection sensor <NUM>, or a pressure sensor <NUM>.

The imaging device 40a shown in <FIG> may be a camera fixed to a hole <NUM> provided in an outer wall of the tower <NUM>, for example as shown in <FIG>, and configured to capture an image of the wind turbine blade <NUM>. In the example shown in <FIG>, the at least one inspection unit <NUM> includes a plurality of imaging devices 40a. The imaging devices 40a are cameras fixed to respective holes <NUM> arranged along the height direction of the tower on the outer wall of the tower <NUM>. Imaging devices 40a may alternatively be moveable for example on a rail along the tower or around the tower. One or more illumination devices, such as lamps, may also be provided to allow for improved imaging.

Further, when the shell of the wind turbine blade <NUM> includes a plurality of layers having different colors as shown in <FIG>, the damage state of the wind turbine blade <NUM> may be inspected based on the color of the shells of the wind turbine blade <NUM> captured by the imaging device 40a.

The microphone 40b shown in <FIG> may be fixed inside the wind turbine blade <NUM>, for example. Since the wind turbine blade <NUM> is formed by joining a plurality of structural parts, when the joint condition of the structural parts deteriorates due to a lightning strike, sound is generated at the joint. Thus, by detecting the sound with the microphone 40b fixed inside the wind turbine blade <NUM>, the damage state of the wind turbine blade <NUM> can be inspected.

The evaluation part 40c inspects the wind turbine blade <NUM> by reading correlation information indicating a relationship between the plurality of lightning parameters (peak value of lightning current, specific energy, and electric charge) and the damage amount of the wind turbine blade <NUM>, and evaluating the damage amount of the wind turbine blade <NUM> based on the correlation information and the plurality of lightning parameters. The correlation information may be generated based on a test result of a lightning protection system, which has been previously performed, and stored in a storage part <NUM>, or may be generated from data of lightning strikes acquired by the actual wind turbine <NUM> and stored in the storage part <NUM>.

The load sensor 41a is fixed to the wind turbine blade <NUM>. When the wind turbine blade <NUM> is damaged, such as cracked or chipped, the load is increased as compared with the normal state of the wind turbine blade. Thus, by detecting the load on the wind turbine blade <NUM> with the load sensor 41a, the damage state of the wind turbine blade <NUM> can be inspected. The load sensor may be, for example, an optical fiber sensor or a strain gauge.

When the drone 41b is used, the wind turbine blade <NUM> can be inspected with a desired inspection method by bringing the drone 41b close to any portion of the wind turbine blade <NUM>.

The evaluation part 41c inspects the wind turbine blade <NUM> by reading a power curve indicating a relationship between the wind speed and the output of the wind turbine <NUM> (amount of power generated by generator <NUM>) from the storage part <NUM>, and comparing the output of the wind turbine <NUM> after the wind turbine blade <NUM> is struck by lightning with the power curve to evaluate the damage state of the wind turbine blade <NUM>. For instance, when the output of the wind turbine <NUM> struck by lightning is lower than the output indicated by the power curve, it may be determined that the wind turbine blade <NUM> is damaged.

The electrical resistance sensor 41d inspects the damage state of the wind turbine blade <NUM> by detecting the electrical resistance of a conductor portion (in the example shown in <FIG>, a portion composed of the metal layer <NUM> and the conductive material <NUM>) of the wind turbine blade <NUM>. The electrical resistance sensor 41d may apply a current between the blade tip and the blade root of the wind turbine blade <NUM>, for example, using the drone 41b (see <FIG>) to detect the electrical resistance.

The acceleration sensor 41e is fixed to the wind turbine blade <NUM>. The acceleration sensor 41e measures vibration of the blade of the wind turbine, converts the vibration into a spectrum by fast Fourier transform (FFT), and inspects the damage state of the blade by pattern recognition based on the peak deviation and the amplitude deviation, comparison of three wind turbine blades <NUM>, and signal strength, and/or a comparison of the pattern of the blade with a historical pattern for the same blade.

The optical sensor 41f inspects the damage state of the wind turbine blade <NUM> by detecting the load applied to the wind turbine blade <NUM> and the deflection of the wind turbine blade <NUM> by a laser and a reflector disposed inside the wind turbine blade <NUM> or the tower <NUM>.

The deflection sensor <NUM> inspects the damage state of the wind turbine blade <NUM> by detecting the load applied to the wind turbine blade <NUM> and the deflection of the wind turbine blade <NUM> by a camera and a reflector disposed inside the wind turbine blade <NUM> for pitch control.

The pressure sensor <NUM> inspects the damage state of the wind turbine blade <NUM> by detecting the internal pressure of the wind turbine blade <NUM>. When lightning strikes the wind turbine blade <NUM>, the internal pressure of the wind turbine blade <NUM> increases, and the joint condition of structural parts constituting the wind turbine blade <NUM> deteriorates. As a result, the holding force of a receptor (not shown) provided at the tip of the wind turbine blade <NUM> is reduced, so that the receptor may be detached. Therefore, the internal pressure of the wind turbine blade <NUM> and/or development of the pressure over time can be used as an indicator of the damage state of the wind turbine blade <NUM>.

Hereinafter, an example of a method for monitoring the wind turbine <NUM> by the wind turbine monitoring device <NUM> will be described. <FIG> is a flowchart showing an example of a method for monitoring the wind turbine <NUM> by the wind turbine monitoring device <NUM>.

First, in S101, the lightning level determination part <NUM> judges whether the current sensor <NUM> detects a lightning strike on the wind turbine blade <NUM>, based on the output of the current sensor <NUM>.

In S101, if the current sensor <NUM> does not detect a lightning strike, i.e., if the current sensor <NUM> does not detect a current (in the case where the current sensor <NUM> is disposed for each wind turbine blade <NUM> as described above, if none of the current sensors <NUM> detects a current), in S102, the operation of the wind turbine <NUM> is continued. The expression "continuing operation of wind turbine <NUM>" means that the rotor <NUM> is rotating and the power generation by the generator <NUM> continues.

In S101, if the current sensor <NUM> detects a lightning strike, i.e., if the current sensor <NUM> detects a current (in the case where the current sensor <NUM> is disposed for each wind turbine blade <NUM> as described above, if any of the current sensors <NUM> detects a current), in S103, the inspection control part <NUM> stops the operation of the wind turbine <NUM> regardless of the level of the lightning strike. The expression "stopping operation of wind turbine <NUM>" means that the rotor <NUM> is stopped and the power generation by the generator <NUM> is stopped.

In S104, the lightning parameter acquisition part <NUM> acquires a peak value of lightning current flowing through the wind turbine blade <NUM> due to the lightning strike, a specific energy of the lightning strike obtained by integrating the square of the lightning current over the duration of the lightning strike, and an electric charge of the lightning strike obtained by integrating the lightning current over the duration of the lightning strike as lightning parameters, based on the output of the current sensor <NUM>. Then, the lightning level determination part <NUM> determines whether the level of the lightning strike detected by the current sensor <NUM> is Q1, based on the three lightning parameters acquired by the lightning parameter acquisition part <NUM>. The lightning level determination part <NUM> determines that, if all of the above-described conditions <NUM>, <NUM>, and <NUM> are satisfied, the level of the lightning strike is Q1.

In S104, if it is determined that the level of the lightning strike is Q1, in S105, the inspection control part <NUM> judges that inspection of the wind turbine blade <NUM> by the inspection unit <NUM> and inspection of the wind turbine blade <NUM> by the inspection unit <NUM> are both unnecessary, and restarts the operation of the wind turbine <NUM> without inspecting the wind turbine blade <NUM>.

In S104, if it is determined that the level of the lightning strike is not Q1, in S106, the lightning level determination part <NUM> determines whether the level of the lightning strike is Q4. The lightning level determination part <NUM> determines that, if at least one of the above-described conditions <NUM>, <NUM>, and <NUM> is satisfied, the level of the lightning strike is Q4.

In S106, if it is determined that the level of the lightning strike is Q4, in S107, the inspection control part <NUM> transmits information indicating that it is necessary to perform inspection (detailed inspection such as visual inspection) of the wind turbine blade <NUM> by a person and rapidly repair the wind turbine blade <NUM> without restarting the operation of the wind turbine <NUM> to a maintenance company of the wind turbine <NUM> or the like.

In S106, if it is determined that the level of the lightning strike is not Q4, in S108, the it is determined whether the level of the lightning strike is Q3. If the level of the lightning strike is neither Q1 nor Q4, and if at least one of the above-described conditions <NUM>, <NUM>, and <NUM> is satisfied, the lightning level determination part <NUM> determines that the level of the lightning strike is Q3.

In S108, if it is determined that the level of the lightning strike is Q3, in S109, remote inspection of the wind turbine blade <NUM> by the at least one inspection unit <NUM> is instructed. For instance, information indicating that it is necessary to perform remote inspection of the wind turbine blade <NUM> by the at least one inspection unit <NUM> is transmitted to a maintenance company of the wind turbine <NUM>. Further, in S110, it is judged whether to restart the operation of the wind turbine <NUM>, based on a result of the remote inspection of the wind turbine blade <NUM> by the at least one inspection unit <NUM>. Additionally, in S108, if it is determined that the level of the lightning strike is Q3, a person may be sent within a predetermined period (for example, within <NUM> months) to perform detailed inspection or repair of the wind turbine blade <NUM>.

In S108, if it is determined that the level of the lightning strike is not Q3, since at least one of the above-described conditions <NUM>, <NUM>, and <NUM> is satisfied, it is determined that the level of the lightning strike is Q2. In this case, in S111, the inspection control part <NUM> performs automatic inspection of the wind turbine blade <NUM> by the at least one inspection unit <NUM>. In S112, the inspection control part <NUM> judges whether to restart the operation of the wind turbine, based on a result of the automatic inspection in S111. Additionally, in S108, if it is determined that the level of the lightning strike is Q2, a person may be sent within a period longer than the predetermined period (for example, within <NUM> months) to perform detailed inspection or repair of the wind turbine blade <NUM>.

Next, another example of a method for monitoring the wind turbine <NUM> by the wind turbine monitoring device <NUM> will be described. <FIG> is a flowchart showing another example of a method for monitoring the wind turbine <NUM> by the wind turbine monitoring device <NUM>.

First, in S201, the lightning level determination part <NUM> determines whether the current sensor <NUM> detects a lightning strikes on the wind turbine blade <NUM>, based on the output of the current sensor <NUM>.

In S201, if the current sensor <NUM> does not detect a lightning strike, i.e., if the current sensor <NUM> does not detect a current (in the case where the current sensor <NUM> is disposed for each wind turbine blade <NUM> as described above, if none of the current sensors <NUM> detects a current), in S202, the operation of the wind turbine <NUM> is continued.

In S201, if the current sensor <NUM> detects a lightning strike, i.e., if the current sensor <NUM> detects a current (in the case where the current sensor <NUM> is disposed for each wind turbine blade <NUM> as described above, if any of the current sensors <NUM> detects a current), in S203, the lightning parameter acquisition part <NUM> acquires a peak value of lightning current flowing through the wind turbine blade <NUM> due to the lightning strike, a specific energy of the lightning strike obtained by integrating the square of the lightning current over the duration of the lightning strike, and an electric charge of the lightning strike obtained by integrating the lightning current over the duration of the lightning strike as lightning parameters, based on the output of the current sensor <NUM>. Then, the lightning level determination part <NUM> determines whether the level of the lightning strike detected by the current sensor <NUM> is Q1, based on the three lightning parameters acquired by the lightning parameter acquisition part <NUM>. The lightning level determination part <NUM> determines that, if all of the above-described conditions <NUM>, <NUM>, and <NUM> are satisfied, the level of the lightning strike is Q1.

In S203, if it is determined that the level of the lightning strike is Q1, in S204, the inspection control part <NUM> judges that inspection of the wind turbine blade <NUM> by the inspection unit <NUM> and inspection of the wind turbine blade <NUM> by the inspection unit <NUM> are both unnecessary, and continues the operation of the wind turbine <NUM> without inspecting the wind turbine blade <NUM>.

In S203, if it is determined that the level of the lightning strike is not Q1 (if the level of lightning strike is more severe than Q1), in S205, the inspection control part <NUM> stops the operation of the wind turbine <NUM>.

The subsequent steps S206 to S212 are the same as S106 to S112 described with reference to <FIG>, so description thereof will be omitted.

The present disclosure is not limited to the embodiments described above, but includes modifications to the embodiments described above, and embodiments composed of combinations of those embodiments.

For instance, if the level of the lightning strike is Q4, the inspection control part <NUM> may perform not only visual inspection of the wind turbine blade <NUM> by a person but also automatic inspection of the wind turbine blade <NUM> by the inspection unit <NUM>, or remote inspection of the wind turbine blade by the inspection unit <NUM>.

Further, if the level of the lightning strike is Q3, the inspection control part <NUM> may perform not only remote inspection of the wind turbine blade by the inspection unit <NUM> but also automatic inspection of the wind turbine blade <NUM> by the inspection unit <NUM>.

In the above-described embodiment, the lightning parameter acquisition part <NUM> acquires a peak value of lightning current flowing through the wind turbine blade <NUM> due to the lightning strike, a specific energy of the lightning strike obtained by integrating the square of the lightning current over the duration of the lightning strike, and an electric charge of the lightning strike obtained by integrating the lightning current over the duration of the lightning strike as lightning parameters, based on the output of the current sensor <NUM>. However, the lightning parameter acquired by the lightning parameter acquisition part <NUM> is not limited to the three parameters, but may include a current, an energy, an electric charge due to the lightning strike on the wind turbine blade <NUM>, or at least one parameter derived from at least one of the current, the energy or the electric charge.

Although in the above-described embodiment, the wind turbine monitoring device <NUM> arranged inside the nacelle <NUM> has been described, the wind turbine monitoring device <NUM> may be disposed in a remote place apart from the wind turbine <NUM> and may be configured to monitor the wind turbine <NUM> through communication with the wind turbine <NUM>. In this case, similarly, the wind turbine <NUM> and the wind turbine monitoring device <NUM> constitutes a wind turbine system.

The contents described in the above embodiments would be understood as follows, for instance.

With the wind turbine monitoring device described in the above (<NUM>), since the lightning level determination part determines the level of the lightning strike using the lightning parameter based on the output of the lightning sensor, it is possible to determine the level of the lightning strike corresponding to the magnitude of the damage risk of the wind turbine blade.

Further, since the inspection control part judges whether it is necessary to automatically inspect the wind turbine blade by the at least one inspection unit for inspecting the wind turbine blade according the level of the lightning strike determined by the lightning level determination part, it is possible to appropriately judge whether it is necessary to automatically inspect the wind turbine blade according to the magnitude of the damage risk of the wind turbine blade.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>), the at least one lightning parameter includes a current, an energy, an electric charge due to the lightning strike on the wind turbine blade, or at least one parameter derived from at least one of the current, the energy or the electric charge.

With the wind turbine monitoring device described in the above (<NUM>), it is possible to appropriately judge whether it is necessary to automatically inspect the wind turbine blade, according to the level of the lightning strike determined based on a current, an energy, an electric charge due to the lightning strike, or at least one parameter derived from at least one of the current, the energy or the electric charge.

(<NUM>) According to the invention, in the wind turbine monitoring device described in the above (<NUM>) or (<NUM>), the inspection control part is configured to: if the level of the lightning strike is a first level (e.g., Q1 described above), judge that it is unnecessary to automatically inspect the wind turbine blade by the at least one inspection unit; and if the level of the lightning strike is a second level (e.g., Q2 described above) more severe than the first level, perform automatic inspection of the wind turbine blade by the at least one inspection unit.

With the wind turbine monitoring device described in the above (<NUM>), if the level of the lightning strike on the wind turbine blade is the first level of low severity, the automatic inspection of the wind turbine blade by the inspection unit is not performed, while if the level of the lightning strike is the second level more severe than the first level, the automatic inspection of the wind turbine blade by the inspection unit is performed. Thus, it is possible to appropriately perform the automatic inspection by the inspection unit according to the level of the lightning strike without excessively performing the inspection.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>), the inspection control part is configured to, when the lightning sensor detects a lightning strike on the wind turbine blade, stop the operation of the wind turbine regardless of the level of the lightning strike.

With the wind turbine monitoring device described in the above (<NUM>), it is possible to avoid a risk associated with continuing the operation of the wind turbine struck by lightning. The wind turbine monitoring device described in the above (<NUM>) can be applied to a wind turbine monitoring device that monitors a wind turbine installed in a country, a region, or the like where it is obliged to stop the operation of the wind turbine regardless of the level of lightning when the wind turbine is struck by lightning.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>), the inspection control part is configured to, if the level of the lightning strike is the first level, restart the operation of the wind turbine without automatically inspecting the wind turbine blade by the at least one inspection unit.

With the wind turbine monitoring device described in the above (<NUM>), if the level of lightning strike is the first level, which has a negligible impact on the wind turbine, the wind turbine is promptly restarted without automatically inspecting the wind turbine blade. Thus, it is possible to suppress an increase in risk associated with the operation of the wind turbine struck by lightning while suppressing a decrease in the operating rate of the wind turbine.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>), the inspection control part is configured to, when the lightning sensor detects a lightning strike on the wind turbine blade, continue the operation of the wind turbine without stopping if the level of the lightning strike is the first level, and stop the operation of the wind turbine if the lightning strike is more severe than the first level.

With the wind turbine monitoring device described in the above (<NUM>), if the level of lightning strike is the first level, which has a negligible impact on the wind turbine, the operation of the wind turbine is not stopped but continued, while if the level of the lightning strike is more severe than the first level, the operation of the wind turbine is stopped. Thus, it is possible to suppress an increase in risk associated with the operation of the wind turbine struck by lightning while suppressing a decrease in the operating rate of the wind turbine. The wind turbine monitoring device described in the above (<NUM>) can be applied to a wind turbine monitoring device that monitors a wind turbine installed in a country, a region, or the like where it is not obliged to stop the operation of the wind turbine regardless of the level of lightning when the wind turbine is struck by lightning.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the any one of above (<NUM>) to (<NUM>), the inspection control part is configured to, if the level of the lightning strike is the second level, perform automatic inspection of the wind turbine blade by the at least one inspection unit after stopping the operation of the wind turbine, and judge whether to restart the operation of the wind turbine based on a result of the automatic inspection of the wind turbine blade by the at least one inspection unit.

With the wind turbine monitoring device described in (<NUM>), if the level of the lightning strike is the second level more severe than the first level, it is judged whether to restart the operation of the wind turbine based on a result of the automatic inspection of the wind turbine blade by the inspection unit. Thus, it is possible to appropriately judge whether to restart the operation of the wind turbine in consideration of the damage state of the wind turbine blade due to the lightning strike.

(<NUM>) According to the invention, in the wind turbine monitoring device described in the any one of above (<NUM>) to (<NUM>), the inspection control part is configured to, if the level of the lightning strike is a third level (e.g., Q3 described above) more severe than the second level, instruct inspection of the wind turbine blade by a different type of inspection unit (e.g., inspection unit <NUM> described above) from the at least one inspection unit.

With the wind turbine monitoring device described in the above (<NUM>), if the wind turbine blade is struck by lightning of the third level more severe than the second level, inspection of the wind turbine blade by an inspection unit that can perform more detailed inspection than the at least one inspection unit is prompted. Thus, it is possible to inspect the wind turbine blade with a suitable inspection unit according to the level of the lightning strike.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>), the at least one inspection unit includes at least one of an imaging device (e.g., imaging device 40a described above), a microphone (e.g., microphone 40b described above), or an evaluation part (e.g., evaluation part 40c described above) configured to evaluate a damage amount of the wind turbine blade based on the at least one lightning parameter. The different type of inspection unit from the at least one inspection unit includes at least one of a load sensor (e.g., load sensor 41a described above), a drone (e.g., drone 41b described above), an evaluation part (e.g., evaluation part 41c described above) configured to evaluate a damage state of the wind turbine blade based on an output of the wind turbine, an electrical resistance sensor (e.g., electrical resistance sensor 41d described above), an acceleration sensor (e.g., acceleration sensor 41e described above), an optical sensor (e.g., optical sensor 41f described above), a deflection sensor (e.g., deflection sensor <NUM> described above), or a pressure sensor (e.g., pressure sensor <NUM> described above).

With the wind turbine monitoring device described in the above (<NUM>), if the level of the lightning strike is the first level, simple inspection can be rapidly performed, while if the level of the lightning strike is the second level more severe than the first level, more detailed inspection can be performed.

(<NUM>) In some embodiments, in the wind turbine monitoring device described in the above (<NUM>) or (<NUM>), the inspection control part is configured to, if the level of the lightning strike is a fourth level (e.g., Q4 described above) more severe than the third level, transmit information indicating that it is necessary to manually inspect the wind turbine blade without restarting the operation of the wind turbine.

With the wind turbine monitoring device described in (<NUM>), if the level of the lightning strike is the fourth level more severe than the third level, detailed inspection of the wind turbine blade by a person is prompted without restarting the operation of the wind turbine in consideration of high damage risk of the wind turbine blade. After the wind turbine blade is inspected in detail and repaired as necessary, the operation of the wind turbine blade may be restarted.

(<NUM>) A wind turbine system according to the present disclosure comprises the wind turbine monitoring device described in any one of the above (<NUM>) to (<NUM>) and the wind turbine.

With the wind turbine system described in the above (<NUM>), it is possible to appropriately judge whether it is necessary to automatically inspect the wind turbine blade, according to the level of the lightning strike on the wind turbine blade.

(<NUM>) In some embodiments, in the wind turbine system described in the above (<NUM>), the lightning sensor is a current sensor (e.g., current sensor <NUM> described above) for detecting a current flowing through the wind turbine blade.

With the wind turbine system described in the above (<NUM>), by determining the level of the lightning strike using the lightning parameter based on the current flowing through the wind turbine blade, it is possible to appropriately judge whether it is necessary to automatically inspect the wind turbine blade by the at least one inspection unit.

(<NUM>) A wind turbine monitoring method according to the present disclosure is a method for monitoring a wind turbine (e.g., wind turbine <NUM> described above) including a lightning sensor (e.g., current sensor <NUM> described above) for detecting a lightning strike on a wind turbine blade (e.g., wind turbine blade <NUM> described above), comprising: acquiring at least one lightning parameter based on an output of the lightning sensor; and judging whether it is necessary to automatically inspect the wind turbine blade by at least one inspection unit (e.g., inspection unit <NUM> described above) for inspecting the wind turbine blade, according the level of the lightning strike determined based on the at least one lightning parameter.

Claim 1:
A wind turbine monitoring (<NUM>) device for monitoring a wind turbine (<NUM>) including a lightning sensor (<NUM>) for detecting a lightning strike on a wind turbine blade (<NUM>), comprising:
a lightning parameter acquisition part (<NUM>) configured to acquire at least one lightning parameter based on an output of the lightning sensor (<NUM>);
a lightning level determination part (<NUM>) configured to determine a level of the lightning strike based on the at least one lightning parameter acquired by the lightning parameter acquisition part (<NUM>); and
an inspection control part (<NUM>) configured to judge whether it is necessary to automatically inspect, without any manual operation, the wind turbine blade (<NUM>) by at least one inspection unit for inspecting the wind turbine blade, according to the level of the lightning strike determined by the lightning level determination part (<NUM>);
wherein the inspection control part (<NUM>) is configured to:
if the level of the lightning strike is a first level (Q1), judge that it is unnecessary to automatically inspect, without any manual operation, the wind turbine blade by the at least one inspection unit (<NUM>);
if the level of the lightning strike is a second level (Q2) more severe than the first level, perform automatic inspection, without any manual operation, of the wind turbine blade by the at least one inspection unit (<NUM>); and
if the level of the lightning strike is a third level (Q3) more severe than the second level, instruct inspection of the wind turbine blade by a different type of inspection unit (<NUM>) from the at least one inspection unit (<NUM>).