Oscillation monitoring
Oscillation monitoring detects excessive oscillation or excursion of the wind energy converter tower
top.
Two acceleration sensors detect the acceleration of the nacelle along the direction of the hub axis
(longitudinal oscillation) and perpendicular to this axis (transverse oscillation). The WEC control
system uses this input to calculate the tower excursion compared to its resting position. If the ex‐
cursion exceeds the permissible limit, the wind energy converter stops. It restarts automatically af‐
ter a short delay. The acceleration sensors are mounted on the same support as the vibration sen‐
sor. If multiple out-of-range tower oscillations are recorded within a 24-hour period, the wind ener‐
gy converter does not attempt any further restarts.
Temperature monitoring
The components of the ENERCON wind energy converter are cooled by an air cooling system. In
addition, temperature sensors continuously measure the temperature of WEC components that
need to be protected from excessive heat.
In the event of excessive temperatures, the power output of the wind energy converter is reduced.
If necessary, the WEC stops. The wind energy converter cools down and typically restarts auto‐
matically as soon as the temperature falls below a predefined limit.
Some measuring points are equipped with additional overtemperature switches. These also initiate
a stop of the wind energy converter, but without an automatic restart after cooling down, once the
temperature exceeds a specific limit.
At low temperatures, some assemblies such as the pitch system emergency power supply and the
generator are heated in order to keep them operational.
Noise monitoring sensors
Sensors located in the rotor head respond to loud knocking sounds such as might be caused by
loose or defective components. If any of these sensors detects any noise and there is nothing to
indicate a different cause, the wind energy converter stops.
In order to rule out exterior causes for the noise (mainly the impact of hail during a thunderstorm),
the signals from all wind energy converters in a wind farm are matched against each other. If the
sensors in multiple WECs are detecting noise at the same time, an exterior cause is assumed. The
noise sensors are deactivated briefly so that none of the wind energy converters in the wind farm
stops. For wind energy converters outside of wind farms, the signal from a noise sensor in the ma‐
chine house is used for reference.
Cable untwisting
If the nacelle of the wind energy converter has turned around its own axis up to three times and
twisted the cables running down inside the tower, the WEC control system uses the next opportuni‐
ty to automatically untwist the cables.
The cable untwisting system includes a sensor system with an angle encoder with two programma‐
ble relays that travel along in the yaw bearing gear rim. If outside the permitted range, the power
supply to the yaw motors is cut.
Safety system
D0376616-2 / DA 11 of 21
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