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9.0 Wind Turbine Operation
NOTICE: Use of the material contained in this document is subject to the warning on page Iv and the disclaimer
on page v of this document.
DOC012R02 AOC 15/50 User Manual Nov 2001
69
9.1.1 Turbine TEST/OFF/ON
Turbine OFF:
This is the normal OFF mode. All brakes are deployed with the brake relays de-energized. The
main contactor is de-energized, disconnecting the turbine from the grid. The PLC disregards all
other sensors while the switch is set to OFF. The brake light should be ON. The high wind,
brake cooling cycle or other fault lights may also be ON, subject to conditions.
Turbine ON:
This is the normal ON mode. The PLC continuously monitors the system parameters for wind
turbine readiness and for fault conditions.
In the absence of faults, the wind turbine is in the ready mode and the ready light will be ON.
At low wind speeds the brake light will be ON indicating that the wind turbine is parked. When
the wind speed average is above 4.9 m/s (11 mph) the PLC will release the brakes allowing the
turbine to freewheel up to speed and come on line as follows:
• The brake relays are energized.
• The tip brake magnets are energized and hold the tip brake plates closed.
• The dynamic brake relay is energized, disconnecting the dynamic brake resistors and
capacitors from the generator output.
• The parking brake solenoid is energized, releasing the high-speed shaft, thereby allowing
it to rotate freely.
• In sufficiently strong winds the wind turbine freewheels up to speed and is monitored by
the controller.
• When the high-speed shaft reaches 1500 rpm (50 Hz wind turbine) or 1800 rpm (60 Hz
wind turbine), the PLC energizes the main contactor connecting the generator to the grid
and turns the online light ON.
If the wind speed average drops below 3.6 m/s (8 mph), the wind turbine will go through a
normal shutdown procedure as follows:
• The main contactor disconnects from the grid.
• The tip brake and dynamic brake relays deploy.
• The brake light lights up.
• The parking brake relay deploys after 4 seconds.
• The brake cooling cycle light lights up; the cooling cycle typically runs for 15 minutes.
The brake cooling cycle allows the dynamic brake resistors and parking brake to cool to ambient
temperatures. During this period, the PLC overrides the wind speed sensor, thereby preventing
the wind turbine from reconnecting to the grid. At the end of the cooling cycle, the PLC reverts
to the normal control mode with the wind turbine ready light ON.