Monitoring of Blade Frequencies of a Wind Turbine

A method for monitoring blade frequencies of a wind turbine, comprising:

• providing a first bolt gauge, which includes a built-in load cell;
• providing a rotating hub including a pitch bearing, which includes an inner ring and an outer ring,
• the outer ring is connected to a hub by a plurality of bolts, each of which is secured by a tightening means,
• the inner ring is connected to a plurality of rotating blades by a plurality bolts, each of which is secured by a tightening means,
• the first bolt gauge positioned on a first bolt of the plurality of bolts of the outer ring between the pitch bearing and the tightening means of the first bolt, or
• the first bolt gauge positioned on a first bolt of the plurality of bolts of the inner ring between the pitch bearing and the tightening means of the first bolt, or
• detecting a load or pressure via the bolt gauge;
• and
• receiving an electrical signal for the detected load or detected pressure which is used to measure the vibrations and/or frequencies of the plurality of rotating blades.

A monitoring system monitoring the blade frequencies of a wind turbine (1) comprising:

• a first bolt gauge, which includes a built-in load cell;
• and
• a rotating hub including a pitch bearing, which includes an inner ring and an outer ring,
• the outer ring is connected to the hub by a plurality of bearing bolts, each of which is secured by a tightening means, wherein
• the inner ring is connected to at least one rotating blade by a plurality blade bolts, each of which is secured by a tightening means,
• the first bolt gauge positioned on a first bearing bolt of the plurality of bearing bolts between the pitch bearing and the tightening means of the first bearing bolt, or
• the first bolt gauge positioned on a second blade bolt of the plurality of blade bolts between the pitch bearing and the tightening means of the first blade bolt.