Environmental Engineering Reference
In-Depth Information
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rotor speed (variable speed systems)
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power factor (capacitor or generator control systems)
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wind turbine normal and emergency shutdowns
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diagnostics for fault detection
Solid-state or conventional mechanical relays are used to activate the associated mecha-
nisms. Time-delay devices or the control software are used to prevent frequent wind turbine
starts and stops when the wind speeds loiter around the turbine's cut-in and cut-out speeds. In
addition to its operational duties, the central microprocessor generally monitors and records
the following performance parameters:
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wind turbine status (on-line or disabled)
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cumulative wind turbine availability
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wind speed and direction
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generator output
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cumulative energy produced
Some central computers compare the actual power and energy performances of each
individual wind turbine to its expected performance ( i.e. , expected output vs . wind speed) and
provide a figure of merit for each machine. This information allows the operator to identify
machines that may need adjustment or maintenance. Another feature that has been incor-
porated into central processors is the ability to calculate cumulative revenues for each wind
turbine and for the entire wind power station.
In addition to electrical protection, wind turbines employ various other sensors to protect
the machinery from damage and to assist in the control of the machine. The following items
have been monitored for these purposes:
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wind speed
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wind direction
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nacelle orientation
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rotor speed
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blade pitch angle (for variable pitch wind turbines)
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equipment vibration levels
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gearbox oil level, temperature, and pressure
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generator speed
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brake pad thickness
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hydraulic fluid level, temperature, and pressure
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bearing temperatures
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structural integrity ( e.g ., by strain gauges, crack detectors and bolt damage sensors)
Transport and Assembly
Transport of wind turbine components from manufacturing plants and system assembly
at the site remain significant cost factors. Table 4-6 [Griffin 200] summarizes the signifi-
cant transportation limitations on the major components of a large-scale wind turbine. While
a number of the components of a wind turbine add to transport and assembly costs, the blades
and the tower are the most significant.
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