WIRELESS DEVICES EMBEDDED THEREIN

The present invention relates to a method for the production of a wind turbine component having one or more wireless devices embedded therein and to the wind turbine component produced by such a method.

In order to optimise the extraction of energy from the wind, wind turbines are typically equipped with a number of sensor systems for providing feedback to the control systems of the turbine. For example, sensor systems are commonly used for monitoring environmental conditions at the wind turbine and for measuring parameters of the wind turbine blades, such as strain. Using the data obtained from these sensor systems, the operational parameters of the wind turbine, such as the pitch of the blades or the yaw of the nacelle, can be adjusted in order to make the wind turbine as efficient as possible at generating energy and also to prevent damage to the wind turbine components.

Sensor systems are often mounted on the surface of wind turbine blades in order to monitor a parameter at the blade surface. The systems are typically put in place after the manufacture of the blades and the mounting and maintenance of the sensor systems on the blades can be complex and time consuming. Furthermore, the sensor systems may be subjected to relatively high levels of mechanical strain as well as the potentially harsh environmental conditions, including for example significant changes in temperature and humidity as well as exposure to dirt and ice on the blade surface.

In certain cases, a sensor system may be mounted within the blade to protect it to a certain extent from the environmental conditions; however, the system may still be subjected to high levels of stress due to bending or vibration. This may adversely affect the functioning and lifetime of the sensor systems, especially those having sensitive electronic components.

A further problem associated with mounting electronic components of sensor systems on the wind turbine blades is that such components are particularly susceptible to lightning strikes and may even attract the lightning, thereby increasing the risk of damage to both the blade and the sensor system. It has been proposed to minimise this problem through the use of wireless devices mounted on the blade, or optical fibres. However, this does not overcome the other problems associated with the mounting of sensor systems on or inside the blade. It would therefore be desirable to provide an improved way to incorporate a sensor system into a wind turbine component, which overcomes these problems. According to a first aspect of the present invention there is provided a method for producing a wind turbine component having one or more wireless devices embedded therein, the method comprising the steps of:

a) providing fibrous reinforcement material in a mould;

b) adding the one or more wireless devices to a curable resin;

c) introducing the resin containing the one or more wireless devices into the closed mould such that the resin and the wireless devices are infused through the fibrous reinforcement material; and

d) curing the resin.

According to a second aspect of the present invention there is provided a moulded wind turbine component comprising a resin matrix having reinforcement fibres distributed therein and further comprising one or more wireless devices embedded within the resin matrix.

Using the method of the present invention it is possible to incorporate one or more wireless devices, such as sensors or transponders, into a wind turbine component during manufacture of the component. This eliminates the need to separately mount the devices and any associated apparatus onto the component after manufacture and is therefore an efficient and cost effective way to incorporate the wireless devices into a component.

The use of wireless devices allows much greater flexibility in the way in which the devices can be incorporated into the material of the wind turbine component, since no connecting wires or cables are required.

In the moulded component produced by the method of the present invention, the one or more wireless devices are embedded within the resin forming the component, rather than being provided on the surface of the component, as in the prior art. Advantageously, the wireless devices are protected from the environmental conditions to which the surface of components, such as blades, may be exposed. Furthermore, the wireless devices are capable of measuring parameters at locations within the composite material in addition to or instead of at the surface of the component. This potentially allows a more accurate and comprehensive measurement of the conditions within the component, or the condition of the composite material forming the component.

As well as being useful to provide an improved means for incorporating sensor systems into a wind turbine component, the method of the present invention can advantageously be used to embed wireless devices which store data about the component and/or about the device itself. This may include, for example, the type of material or production data. The association of such data with the component provides a number of potential benefits in the sale and transport of the components. The method of the present invention uses a type of resin infusion process, such as a resin transfer moulding (RTM) method, in which the one or more wireless devices are incorporated into the resin before the resin is introduced into the mould. The wireless devices are infused into the fibrous material along with the resin and upon curing of the resin, will become fixed in place within the component.

The addition of the wireless devices into the resin can advantageously be carried out automatically and without affecting the resin flow, or the moulding procedure. In particular, no adaptation to the mould apparatus is required and the introduction of the wireless devices will not compromise the subsequent curing process. The method is suitable for all types of wind turbine components formed of moulded composite materials, irrespective of the relative amounts of reinforcement fibres and resin. Thus, it is equally suitable for the insertion of wireless devices into heavily reinforced components, such as spar caps, and resin rich components, such as couplings.

During a resin infusion method, a source of curable resin is pumped, or injected from a resin source into an inlet port of a closed mould, optionally with the use of a vacuum to help draw the resin through the mould. Step (b) of the method of the present invention, in which the one or more wireless devices are added to the resin may be carried out before the resin begins to flow into the mould. Where a plurality of wireless devices are added, the devices may be distributed more evenly through the resin source by a simple mixing step. Alternatively, the one or more wireless devices may be added to the moving resin flow at a point before the resin is introduced into the mould. For example, the apparatus may incorporate an additional inlet for the introduction of the wireless devices into the resin flow, upstream of the inlet port in the mould.

In preferred embodiments of the invention, a plurality of wireless devices are introduced intermittently into a moving stream of resin so that the wireless devices are spaced apart within the resin. For example, each wireless device may be introduced into the stream of resin after a certain time interval from the introduction of the previous wireless device.. Alternatively, a wireless device may be introduced into the stream of resin after a certain volume or mass of resin has flowed passed the inlet point since the introduction of the previous wireless device. These methods make it possible to control to a certain extent the position and spacing of the wireless devices within the component, which may be particularly desirable for larger wind turbine components. For example, it may be desirable to embed wireless sensors at spaced positions along the length of a wind turbine blade.

The insertion of a plurality of wireless devices into a wind turbine component allows conditions to be monitored at different parts of the component and also allows for redundancy of the devices. The plurality of wireless devices may be the same type of device as each other, or may be different types of parameters, which are provided for different purposes.

Preferably, each wireless device comprises a transmitter, for wirelessly transmitting an output signal from the wind turbine component. The transmitter will typically emit an output signal in the form of an electromagnetic wave which can be detected at a suitable distance from the component. Preferably, the transmitter is a radio transmitter.

The output signals from the transmitter may be received by any suitable wireless receiver. The receiver may be permanently mounted on the wind turbine in order to continuously monitor the component during normal use. Alternatively, the receiver may be remote from the wind turbine and may be used to continuously monitor a parameter of the component, or to occasionally monitor the parameter, for example during routine maintenance or servicing of the turbine. The transmitter may also optionally store any measured data, such that it can be extracted at a later stage.

In certain wind turbine components, a transmitter may not be required and the wireless device may include a component that can be detected by a sensor without emitting an output signal, for example, a magnetic tag.

Preferably, one or more of the wireless devices incorporated into the resin comprises a sensor for measuring a parameter of the wind turbine component. The sensor may be provided in combination with a wireless transmitter, as described above, for wirelessly transmitting an output signal with the detected data from the sensor. Alternatively, or in addition, the sensor may be linked to a storage device for storing the detected data from the sensor.

Any type of wireless sensor may be incorporated into the wind turbine component, including but not limited to a temperature sensor, a strain sensor or a voltage sensor.

Alternatively or in addition to providing one or more sensor devices, one or more of the wireless devices incorporated into the resin may comprise a tag, such as a magnetic tag or a radio frequency identification (RFID) tag which can be detected by an appropriate sensor. This type of wireless device may be used to monitor the position or orientation of a component or a part of a component, such as a wind turbine blade. Alternatively, the tag may provide unique data relating to the component, such as the serial number, manufacturer details, or data relating to the manufacture of the component. This allows the component to be uniquely identified and tracked.

The one or more wireless devices may further comprise a power source, such as a battery, which is preferably capable of powering the device over the lifetime of the component. Alternatively, the one or more wireless devices may be powered by a signal sent to the device from a remote device. For example, the one or more wireless devices may include a transponder, such as a radio frequency identification device, that is powered by a radio signal sent to the device from a remote radio transmitter.

At least some of the one or more wireless devices may be operable to monitor a parameter of the wind turbine component during normal operation of the wind turbine into which the component is incorporated. This allows for the continuous monitoring of parameters such as temperature, strain and voltage during operation of the wind turbine, so that the operational parameters of the component can be optimised. It may also enable any problems with the component to be identified.

At least some of the one or more wireless devices may be operable to monitor a parameter of the wind turbine component during the curing step (d) of the production process set out above. The same wireless devices used to monitor a parameter of the component during the curing process may subsequently be used to monitor the same, or a different parameter of the component during normal operation. Alternatively, a combination of wireless devices may be introduced into the component, with some of the devices being operable to measure a parameter during curing and other devices being operable to measure a parameter during normal operation.

The introduction of one or more wireless sensors into the resin during the method of the present invention not only provides an efficient way of incorporating sensor systems to be used during normal operation of the wind turbine, but also enables the use of embedded sensors to optimise the curing process. The use of wireless sensors is preferable to the use of conventional wired sensors, since there are no wires or cables to affect the closure or seal of the mould and it is possible to avoid having unnecessary wires or cables embedded within the component. The use of embedded sensors may be particularly beneficial in the production of relatively thick components, since it allows the monitoring of the conditions deeper within the component, rather than just at the surface. This in turn enables the curing process to be adjusted more specifically.

The preferred type of wireless device for monitoring a parameter of the component during the curing process comprises a temperature sensor operable to detect a temperature parameter of the surrounding resin and transmitter means for transmitting an output signal with the detected temperature data from the sensor. This allows a feedback system to be set up, which makes it possible to carefully control the heating of the component during curing, in response to the measured temperatures. In particular, the heating can be controlled to more accurately provide the desired curing cycle and/or to adjust heating locally, for example, to compensate for heat sinks at certain locations within the component.

The first step of the moulding method according to the invention involves the placement or 'lay-up' of dry fibrous reinforcement material in the mould, typically on the mould surface. This process is well known to the skilled person. The fibrous reinforcement material may be at least partially preformed to the desired shape of the component, if desired. The fibrous reinforcement material may be in any suitable form for a resin infusion moulding method, including but not limited to woven or non woven fabrics, mats, individual or groups of fibres such as tow. Preferably, prior to the infusion of the resin, the fibrous reinforcement material is dry, i.e. substantially free from moisture or resin. The fibrous reinforcement material preferably comprises one or more types of fibres selected from: carbon fibres, glass fibres, aramid fibres, synthetic fibres, bio fibres, mineral fibres or boron fibres.

Once the fibrous reinforcement material is in place on the surface of the mould, a second mould part may be clamped over the first part to define a cavity containing the fibrous reinforcement material. Alternatively, a cavity may be produced through the use of a vacuum bag rather than a mould part, but in this case only one side of the component will have a moulded surface.

The resin is typically premixed with a catalyst, or hardener and the resin is then drawn through the cavity so that it infuses into the fibrous reinforcement material. The resin will typically be introduced into the mould cavity under pressure and optionally, the flow of resin through the cavity may be assisted by the application of vacuum. Once the required amount of resin has been introduced into the mould and the fibrous reinforcement material is sufficiently 'wet', the resin ports will be closed so that the mould cavity is sealed prior to the curing step. The infusion of the resin may take place at ambient temperature, or at an elevated temperature.

The resin may be a thermoplastic or thermosetting resin and may be based on, for example, unsaturated polymer, polyurethane, polyvinyl ester, epoxy or combinations thereof. Most preferably, the resin is an epoxy resin. Resin formations for use in a resin infusion method, such as resin transfer moulding, are well known in the art.

A suitable hardener or catalyst should be selected depending on the type of resin used in the method and the intended curing cycle. Hardeners for use in a resin infusion method are well known in the art.

In step (d) of the method according to the invention, the resin is cured in order to achieve cross-linking and hardening. The cure conditions will depend upon the resin system used and will typically require the application of heat over a specific period of time, although some resins may be cured at ambient temperature. Where heat is required in the curing process, the mould will typically incorporate heaters in order to heat the inner mould surfaces. In some cases, curing may be initiated or accelerated by the incorporation of curing agents into the resin, or by the application of UV light. As the resin cures and hardens, the one or more wireless devices will become fixed within the resin. The method according to the invention is suitable for the production of many different types of composite wind turbine components, but finds particular application in the production of components for wind turbine blades, where the use of sensor systems is important for optimising control of the blades. Other types of component which may be produced by this method include resin rich components, such as couplings.

The present invention also provides a component produced by the method according to the invention set out above having one or more wireless devices embedded therein and in particular, a wind turbine blade component.

The invention will now be further described, by way of example only, and with reference to the accompanying Figure 1.

Figure 1 shows a schematic diagram of the moulding apparatus used to carry out a method according to an embodiment of the invention for producing a wind turbine component having a plurality of wireless sensor devices embedded therein. In the first step of the method, a plurality of fibrous tows 10 are laid on the surface of a first, lower mould part 12. A release agent and/or a gel coat may be applied to the mould surface prior to the fibrous tows, if required. A second, upper mould part 14 is clamped in place over the first mould part 12 and the fibrous tows 10 to create a mould cavity 16.

A source of resin 18 and a source of hardener 20 are provided and each source is connected to a pre-mixing chamber 22 in which the resin 18 and hardener 20 are combined, prior to being introduced into the mould cavity 16. The mixture of resin 18 and hardener 20 from the pre-mixing chamber 22 is introduced into the mould cavity 16 by means of a resin conduit 24 and a resin inlet port 26 provided in the upper mould part 14. Upstream of the pre-mixing chamber, a device inlet port 28 is provided, through which wireless devices 30 may be introduced into the resin flow.

Once the second mould part 14 has been fixed in place using clamping means 32, the flow of resin 18 and hardener 20 is started and the mixture of resin and hardener is injected into the mould cavity 16 from the pre-mixing chamber 22 using pumping means (not shown). Vacuum is applied to the mould cavity 16 to assist the infusion of the resin mixture through the fibrous tows 10. Wireless devices 30 are intermittently introduced into the flow of resin through the device inlet port 28, either automatically or by hand. The wireless devices 30 travel with the resin flow and are infused into the fibrous tows 10 along with the resin. Each wireless device 30 comprises a temperature sensor and a wireless transmitter for transmitting a radio output signal with temperature data from the temperature sensor.

Once the required amount of resin mixture has been pumped into the mould cavity

16, the resin and hardener flows are stopped and the resin inlet port 26 is closed, together with any other inlet or outlet ports in the mould. The resin 18 is then cured by the application of heat to the first 12 and second 14 mould parts, in a defined heating cycle.

During the heating cycle, the temperature at various parts of the resin 18 within the mould is monitored by the wireless temperature sensors 30 and the output signals from the transmitters are received by a radio receiver (not shown). A controller processes the temperature data received from the sensor and calculates the required adjustment to the temperature of the resin material. The controller then sends a signal to adjust the power provided to the heating means, in order to adjust the temperature of the resin to the desired level. Thus, a feedback loop is set up to achieve accurate heating of the resin within the mould.

When the curing process is completed, the moulded component is released from the mould cavity 16 and may be subject to further processing steps, such as painting. The component is then ready to be incorporated into a wind turbine without any further adjustment to the wireless devices 30. Each wireless device 30 includes a battery, so that the lifetime of the device is sufficiently long that it can continue to function throughout the lifetime of the turbine. The wind turbine is equipped with a radio receiver to receive the signals from the transmitter, so that the temperature within the component can be continuously monitored during normal operation of the turbine.

In an alternative embodiment, a combination of wireless temperature sensors 30a and wireless strain sensors 30b are introduced into the resin flow. The temperature sensors 30a may be used to monitor temperature within the component during cure as well as during normal operation, as described above. The strain sensors 30b are distributed throughout the component in order to detect undesirable levels of strain or deformation in the component during normal operation of the wind turbine.