Bearing protection arrangement

1. A bearing protection arrangement of a journal bearing of a wind turbine, the bearing protection arrangement comprising:

a wind speed monitor arranged to monitor wind speed in a vicinity of the wind turbine and to generate a wake-up signal when the monitored wind speed increases from less than a predefined minimum speed to greater than the predefined minimum speed; and

a backup battery having a low-power mode in which only circuitry for receiving the wake-up signal is powered thereby and a normal-power mode in which a brake system of the wind turbine is powered thereby,

a mode switch module configured to:

switch the backup battery from the normal-power mode into the low-power mode when a charge level of the backup battery is less than a predefined minimum capacity, and

switch the backup battery from the low-power mode into the normal-power mode in response to the wake-up signal.

2. The bearing protection arrangement according to claim 1 , wherein the wind speed monitor is incorporated in a wind speed sensor arranged on an exterior of the wind turbine.

3. The bearing protection arrangement according to claim 2 , wherein the wind speed sensor comprises a vertical axis anemometer.

4. The bearing protection arrangement according to claim 3 , wherein the wind speed monitor comprises a rotary encoder configured to generate a digital wind speed value on a basis of a rotational velocity of the vertical axis anemometer.

5. The bearing protection arrangement according to claim 4 , wherein the wind speed monitor comprises a digital signal processor adapted to generate the wake-up signal on the basis of the digital wind speed value.

6. The bearing protection arrangement according to claim 2 , wherein the wind speed monitor comprises an ultrasonic wind speed sensor configured to generate a digital wind speed value.

7. The bearing protection arrangement according to claim 1 , comprising a rechargeable battery arranged to provide power to components of the wind speed monitor.

8. The bearing protection arrangement according to claim 1 , wherein the backup battery is arranged to provide power to a lubricant pump arrangement of the journal bearing in response to the wake-up signal being generated.

9. The bearing protection arrangement according to claim 1 , wherein the backup battery is arranged to provide power to a yaw system of the wind turbine in response to the wake-up signal being generated.

10. A wind turbine comprising:

the bearing protection arrangement according to claim 1 ;

a rotary component and a housing, wherein the journal bearing is arranged between the housing and the rotary component;

a number of auxiliary systems arranged to restart the wind turbine after the wake-up signal is generated.

11. A method of protecting a journal bearing of a wind turbine during standstill, the method comprising:

providing a wind speed monitor to measure wind speed in a vicinity of the wind turbine and to generate a wake-up signal when the measured wind speed increases from less than a predefined minimum speed to greater than the predefined minimum speed;

providing a backup battery having a low-power mode in which only circuitry for receiving the wake-up signal is powered thereby and a normal-power mode in which a brake system of the wind turbine is powered thereby;

switching the backup battery from the normal-power mode into the low-power mode when a charge level of the backup battery is less than a predefined minimum capacity; and

switching the backup battery to the normal-power mode in response to the wake-up signal.

12. The method according to claim 11 , wherein the predefined minimum capacity of the backup battery is determined in a prior step of calculating an amount of energy necessary to turn an aerodynamic rotor of the wind turbine into the wind and to release brakes of the brake system and/or to operate a lubricant pump of the journal bearing.