WO2010123461A1

WO2010123461A1 - A wind turbine comprising a rotor

Info

Publication number: WO2010123461A1
Application number: PCT/SG2010/000155
Authority: WO
Inventors: Yin BO; Heng DENG; Kheng Hong Ang; Xiao Qian Li
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2009-04-21
Filing date: 2010-04-19
Publication date: 2010-10-28
Anticipated expiration: 2011-10-21

Abstract

A wind turbine (1) comprising a rotor (4) is provided, wherein the rotor includes at least one sensor for sensing at least one physical characteristic of the rotor and a power supply unit. The power supply unit (10) is capable of converting light energy into electrical energy for supplying electrical power to the sensor.

Description

A WIND TURBEVE COMPRISING A ROTOR

The present invention relates to a rotor of a wind turbine, and specifically, to a wind turbine comprising a sensor and a power supply unit in the rotor.

Background of the invention

A wind turbine has a rotor which rotates with respect to a stationary portion of the wind turbine. The rotor usually includes a hub and a plurality of blades. When wind is incident on the blades, it causes the rotor to rotate. Most wind turbines are provided with many sensors for obtaining data relating to physical characteristics of components in the wind turbines or to obtain information on the wind.

These sensors may be placed on nacelle, tower, components in the nacelle or tower of the wind turbine. Data obtained from these sensors are provided to a processing unit housed inside the nacelle or tower for processing. Power supply for the sensors in the nacelle or tower may be provided from power generated by the wind turbine or from a separate power supply unit. Sensors may also need to be provided on the hub or blades of the rotor for measuring and monitoring physical properties and characteristics of the blades during the wind turbine's operation. Therefore, corresponding cables need to be provided from the nacelle into the rotor for supplying power to the sensors in the rotor. Additional cables are also needed for transmitting sensed data from the sensors in the rotor to the processing unit in the nacelle.

As the rotor is rotating with respect to the nacelle during operation, cables are provided from the nacelle into the rotor using a slip ring assembly. However, slip ring assemblies have complicated structures and are also prone to failure, resulting in reliability issues. Moreover, providing power supply to sensors in the rotor using electrical cables is not desirable because they are prone to lightning strikes, especially when the cables are in the blades. Furthermore, the movement or deflection of the blades when the wind turbine is in operation may cause the cables in the blades to wear out, resulting in turbine trip or false alarms.

Therefore, it is an object of the invention to supply power to the sensors in the rotor without the disadvantages mentioned above. Summary of the Invention

According to one aspect of the invention, a wind turbine comprising a rotor is provided, wherein the rotor includes at least one sensor for sensing at least one physical characteristic of the rotor and a power supply unit. The power supply unit is capable of converting light energy into electrical energy for supplying electrical power to the sensor.

The wind turbine according to the embodiment does not require electrical cables from the nacelle into the rotor for providing power supply to the sensor. The sensor obtains its power from the power supply unit located in the rotor. Therefore, the complicated slip ring assembly for providing electrical cable from the nacelle to the rotor can be removed. Accordingly, the disadvantages associated with using the slip ring assembly, for example prone to failures, low reliability, etc, can be eliminated. In addition, the power supply unit and the sensor may be placed very close to each other. Therefore, the length of electrical cable from the power supply unit to the sensor can be kept to a minimum. This also greatly reduces the possibility of a lightning strike. Furthermore, by using such an autonomous power supply for sensor in the rotor, any impact from the grid on the power supply is eliminated.

The light energy captured by the supply unit may come from the sun or from any other light source such as lamp posts or spot lights. For example, the sensor may capture light from the sun during the day, and from other artificial light source at night. Thus, power can be supplied to the sensor at all times during the operation of the wind turbine.

It should be noted that "electrical power" in this specification refers to the electricity supplied to a device, in order for the device to function. It is a form of "electrical energy" used to power up the device. Therefore, the term "electrical power" and "electrical energy" may be used interchangeably in this specification.

According to an embodiment, the power supply unit includes at least one photovoltaic cell for capturing and converting light energy into electrical energy. A photovoltaic cell, also known as solar cell, is used for converting any incident light into electrical energy. An interconnected assembly of photovoltaic cells forms a photovoltaic module or panel, also known as solar panel. Other devices capable of capturing light energy and converting it to electrical energy may be used in other embodiments. An example of such device includes a nanoelectronic device.

According to an embodiment, the wind turbine further includes an energy storage unit in the rotor for storing electrical energy from the power supply unit. The energy storage unit supplies electrical power to the sensor when the electrical energy generated from the power supply unit is insufficient. During the day, the power supply unit receives light energy and supplies electrical power converted from the light energy to the sensor. In addition to supplying electrical power to the sensor, the power supply unit also supplies electrical energy to the energy storage unit to be stored therein. When the electrical power from the power supply unit is insufficient, for example at night or during cloudy condition, the stored energy in the energy storage unit is used to supply or supplement electrical power to the sensor. This embodiment hence has the advantage that electrical power can be supplied to the sensor at all times, regardless of whether there is sufficient light energy captured by the power supply unit.

According to an embodiment, the wind turbine further includes a power control unit for controlling at least one of the following: supply of electrical power from the power supply unit to the sensor; supply of electrical power from the power supply unit to the energy storage unit to be stored therein; and supply of electrical power from the energy storage unit to the sensor.

In this embodiment, the power control unit controls the flow of electrical power among the power supply unit, the energy storage unit and the sensor. When there is sufficient light, the power control unit controls the power supply unit to supply electrical power to the sensor and the energy storage unit. When there is insufficient light or the electrical power from the power supply unit is insufficient, the power control unit controls the energy storage unit to supply electrical power to the sensor. The power control unit thus ensures that the sensor always receive electrical power when the wind turbine is in operation.

According to an embodiment, the energy storage unit includes a rechargeable battery. By using a rechargeable battery, the energy storage unit is capable of storing electrical energy from the power supply unit, and supplying electrical power to the sensor by discharging its stored electrical energy when required. It is also possible to use non-rechargeable battery in other embodiments. When a non-rechargeable battery is used, it does not receive electrical energy from the power supply unit. When the electrical power from the power supply unit is insufficient, the non-rechargeable battery supplies electrical power to the sensor. When the electrical power from the non-rechargeable battery is used up, it has to be replaced.

According to an embodiment, the wind turbine includes a hub and at least one blade connected to the hub. The sensor and the power supply unit are located in the blade. By locating both the sensor and the power supply unit in the blade, the length of the electrical cable between the power supply unit and the sensor is minimal. It should be noted that both the power supply unit and the sensor may be located in the hub in another embodiment.

According to an embodiment, the wind turbine includes a light reflector for reflecting light from a light source to the power supply unit. Light from the light source may not directly fall on the power supply unit, especially at night. Light reflector is used to reflect light from the light source onto the power supply unit. Accordingly, the amount of light incident on the power supply unit, and hence the electrical power supplied by the power supply unit, can be increased.

According to an embodiment, the wind turbine includes a nacelle where the rotor is supported from, and a wireless connection means for transmitting data between the rotor and the nacelle. By using wireless connection means for data transmission, any wires or cables between the nacelle and the rotating rotor is totally eliminated. Standard wireless connection means for data transmission known to a person skilled in the art may be used.

In another aspect of the invention, a method for supplying electrical power to at least one sensor located in a rotor of a wind turbine is provided. The method includes receiving light energy by a power supply unit located in the rotor, converting the received light energy to electrical energy, and supplying electrical power to the sensor.

According to an embodiment, the method further includes storing electrical energy into an energy storage unit. According to an embodiment, the method further includes supplying electrical power to the sensor from the energy storage unit when the electrical power supplied by the power supply unit is insufficient.

Brief Description of the Drawings

The invention will be better understood with reference to the detailed description when considered in conjunction with the non-limiting examples and the accompanying drawings.

Figure 1 shows a general setup of a wind turbine.

Figure 2 shows a wind turbine having a solar panel located on one of its blades according to an embodiment.

Figure 3 shows a schematic diagram of a sensor system housed in one of the blades of the wind turbine according to an embodiment.

Figure 4 shows a flow chart of a method for supplying electrical power to a sensor located in a rotor of the wind turbine according to an embodiment.

Detailed Description of the Invention

Figure 1 shows a general setup of a wind turbine 1. The wind turbine 1 includes a tower 2 having a number of tower sections, a nacelle 3 positioned on top of the tower 2, and a rotor 4 extending from the nacelle 3. The tower 2 is erected on a foundation 7 built in the ground. The rotor 4 is rotatable with respect to the nacelle 3, and includes a hub 5 and one or more blades 6.

Wind incident on the blades 6 causes the rotor 4 to rotate with respect to the nacelle 3. The mechanical energy from the rotation of the rotor 4 is converted into electrical energy by a generator (not shown) in the nacelle 3. The generated electrical energy can be supplied to an electrical grid or to a local community. Wind turbines are expected to be in operation for many years. Therefore, various monitoring systems are used to monitor the operating health of the wind turbines. This is done by having many sensors in the wind turbines to obtain data relating to physical characteristics of the components in the wind turbines, and processing these data to determine whether any of the components has a high possibility of failing. When a component is determined to have high possibility of failing, the component is replaced or some other corrective measures are taken. Some sensors may need to be placed in the blades 6 to monitor the physical characteristics of the blades 6, such as mechanical stress on the blades, etc. hi the prior art, as mentioned earlier, cables need to be provided from the nacelle 3 to the sensors in the blades 6 for supplying power and data transmission, resulting in a number of disadvantages. According to the invention, the supply of power to the sensors in the blades 6 or in the hub 5 is possible without the need of power cables from the nacelle 3, and hence, eliminating the corresponding disadvantages.

Although the wind turbine 1 shown in Figure 1 has three blades 6, it should be noted that a wind turbine may have different number of blades. It is common to find wind turbines having one to four blades. The wind turbine 1 shown in Figure 1 is a Horizontal Axis Wind Turbine (HAWT) as the rotor 4 rotates about a horizontal axis. It should be noted that the rotor 4 may rotate about a vertical axis. Such a wind turbine having its rotor rotates about the vertical axis is known as a Vertical Axis Wind Turbine (VAWT). The embodiments described henceforth are not limited to HAWT having 3 blades. They may be implemented in both HAWT and VAWT, and having any number of blades 6 in the rotor 4.

Figure 2 shows the wind turbine 1 having a solar panel 10 on one of its blades 6 according to an embodiment of the invention. The blade 6 having the solar panel 10 also includes a sensor (not shown) connected to the solar panel 10. The solar panel 10 includes a plurality of photovoltaic or solar cells. The photovoltaic cells capture light incident on them, and generate a direct current. Such solar panel is known to one ordinarily skilled in the art. The electrical power produced by the solar panel 10 is proportional to the amount of incident light, and is supplied to the sensor on the blade 6. Therefore, there is no electrical cable from the nacelle 3 to provide electrical power to the sensor in the blade 6.

It should be noted that the solar panel 10 and the sensor may be located in different parts of the rotor 4. For example, both the solar panel 10 and the sensor may be located in the hub 5. Alternatively, the sensor may be located in the blade 6, and the solar panel 10 is located in the hub. Figure 3 shows a schematic diagram of a sensor system housed in one of the blades 6 of the wind turbine according to an embodiment. The sensor system includes a sensor 20, a solar panel 21, a rechargeable battery 22 and a power controller 23. The solar panel 21 includes a plurality of photovoltaic cells (not shown) for capturing light energy and converting them to electrical power. The function of the power controller 23 is to control the flow of electrical power between the sensor 20, the solar panel 21 and the rechargeable battery 22.

When there is sunlight during the day or when artificial light source is present, light incident on the solar panel 21 is captured and converted to electrical energy. The power controller 23 channels the flow of electrical power from the solar panel 21 to the sensor 20 when the wind turbine is operating. At the same time, the power controller 23 also channels part of the electrical power from the solar panel 21 to the rechargeable battery 22. This portion of the electrical power to the rechargeable battery 22 is used to charge the rechargeable battery 22. If the wind turbine is not in operation, all the electrical power produced by the solar panel 21 is used to charge the rechargeable battery 22.

When the amount of sunlight or artificial light source is low, such as during the night or on cloudy days, the electrical power produced by the solar panel 21 may be insufficient to power the sensor 20. Accordingly, electrical power from the rechargeable battery 22 is used to supplement the electrical power from the solar panel 21 for the sensor 20. When the solar panel 21 is unable to produce any electrical power (for example in total darkness), the power controller 23 channels electrical power from the rechargeable battery 22 to the sensor 20. Power for the power controller 23 may be supplied by the solar panel 21 and/or the rechargeable battery 22. According to this embodiment, electrical power is always supplied to the sensor 20 when the wind turbine is in operation, regardless of whether there is enough light.

It should be noted that the schematic diagram of the sensor system shown in Figure 3 is only one of the many possible arrangements. Other arrangements are also possible. For example, one or more sensors 20 may be provided and connected to the power controller 23. The sensors 20 may be located on the same blade 6, or on different blades 6. Also, more than one panel 21 may be used to supply electrical power to the sensor 20. Similarly, more than one rechargeable battery 22 may be used for storing electrical power and providing the electrical power to the sensors 20 when needed. It should also be noted that the rechargeable battery 22 and the power controller 23 are optional, that is, they may be omitted.

Different types of batteries may be used as the rechargeable battery 22 in this embodiment. Examples of rechargeable batteries that may be used include, but not limited to, fuel cell, flow cell, Lithium-Ion (Li-Ion) battery, Nickel Metal Hydride (MiMH) battery and a capacitor. These rechargeable batteries are known to a person skilled in the art.

The power controller 23 includes components such as power converters and corresponding control circuits. The power controller 23 may also include other functions such as maximum power point tracking of the solar panel 21, charging/discharging control of energy storage units or rechargeable batteries and output voltage regulation. Such a power controller 23 can be implemented by a person skilled in the art.

When the wind turbine is operating, the sensor 20 obtains data relating to the physical characteristics of the blade 6. The data is subsequently transmitted to a processing unit (not shown) for processing. The processing unit is normally located in the nacelle 3 or in the tower 2. Therefore, data cable is provided from the nacelle 3 to the blade 6 for data transmission between the sensor 20 and the processing unit.

According to an embodiment, data obtained by the sensor 20 is transmitted to the processing unit in the nacelle 3 or tower 2 using wireless connection means. Therefore, there is no need to have any data cable from the nacelle 3 to the sensor 20 in the blade 6 for data transmission. Examples of wireless connection means include, but not limited to, WLAN 802.11 a/b/n standard and Bluetooth.

It is also possible to channel light from other artificial light source onto the solar panel 10 on the blades 6, so that electrical power can be supplied by the solar panel 10 for a longer period of time. According to an embodiment, one or more light reflectors are used to reflect light onto the solar panel 10. Examples of light reflectors include mirrors. The mirrors may be placed outside the wind turbine, or attached to the wind turbine, for example on the tower 2 or the nacelle 3. In another embodiment, a light source is placed inside the rotor 4, in particular, inside the hub 5. Light from the light source inside the rotor 4 is then channeled to the solar panel 10 inside the blade 6 using optical fiber cable or light reflector. In this embodiment, a double-sided solar panel 10 may be used to capture the light inside the rotor 4 or blade 6. Specifically, the double-sided solar panel 10 has one side facing the inside of the blade 6 to receive light from the light source in the rotor 4. It is also possible that this light source is in the nacelle 3 and is projected into the rotor 4.

Figure 4 shows a flow chart of a method for supplying electrical power to the sensor located in the rotor 4 of the wind turbine 1 according to an embodiment. Step 41 includes receiving light energy by a power supply unit in the rotor 4. In particular, the solar panel 10 on the blade 6 captures the light energy. Step 42 includes converting the light energy into electrical energy. In particular, the solar panel 10 converts the captured light energy into electrical energy. Step 43 includes supplying electrical power to the sensor in the rotor 4. In particular, the solar panel 10 supplies the converted electrical energy as electrical power to the sensor.

As already mentioned earlier, the method described in Figure 4 may further include storing the converted electrical energy into an energy storage unit. The energy storage unit supplies electrical power to the sensor when the electrical power supplied by the power supply unit is insufficient.

It should be emphasized that the above-described embodiments are possible examples of implementations which are merely set forth for a clear understanding of the principles of the invention. The person skilled in the art may make many variations and modifications to the above-described embodiments) of the invention, said variations and modifications are intended to be included herein within the scope of the following claims.

Claims

What is claimed:

1. A wind turbine comprising a rotor, wherein the rotor comprises: at least one sensor for sensing at least one physical characteristic of the rotor; and a power supply unit, wherein the power supply unit is capable of converting light energy into electrical energy for supplying electrical power to the at least one sensor.

2. The wind turbine of claim 1, wherein the power supply unit further comprises at least one photovoltaic cell for capturing and converting light energy into electrical energy.

3. The wind turbine of claim 1 or 2, wherein the rotor further comprises: an energy storage unit, wherein the energy storage unit stores electrical energy from the power supply unit and supplies electrical power to the at least one sensor when the electrical power from the power supply unit is insufficient.

4. The wind turbine of any of claims 1 to 3, further comprising: a power control unit, wherein the power control unit is adapted to control at least one of the following: supply of electrical power from the power supply unit to the at least one sensor; supply of electrical power from the power supply unit to the energy storage unit to be stored therein; and supply of electrical power from the energy storage unit to the at least one sensor.

5. The wind turbine of any of claims 1 to 4, wherein the energy storage unit comprises a rechargeable battery.

6. The wind turbine of any of the preceding claims, wherein the rotor further comprises: a hub; and at least one blade connected to the hub, wherein the at least one sensor and the power supply unit are located in the at least one blade.

7. The wind turbine of any of the preceding claims, further comprising: a light reflector for reflecting light from a light source to the power supply unit.

8. The wind turbine of any of the preceding claims, further comprising: a nacelle where the rotor is supported therefrom; and a wireless connection means for transmitting data between the rotor and the nacelle.

9. A method for supplying electrical power to at least one sensor located in a rotor of a wind turbine, the method comprising: receiving light energy by a power supply unit located in the rotor; converting the received light energy to electrical energy; and supplying the electrical power to the sensor.

10. The method according to claim 9, further comprising storing electrical energy into an energy storage unit.

11. The method according to claim 10, further comprising supplying electrical power to the sensor from the energy storage unit when the electrical power supplied by the power supply unit is insufficient.