Topic 2-WT Drivetrain Design Flashcards
What is the drivetrain of a wind turbine? What is the indirect or direct drivetrain design of a wind turbine? For the NREL 750 kW wind turbinedesign, identify the components belong to the drivetrain.
The drivetrain consists of all the rotating components of the wind turbine (excluding the rotor hub), including the main shaft, gearbox, couplings, brakes, and generator.
For indirect and direct drivetrain designs, state the most important advantage and the most important disadvantage.
Indirect drivetrain: most large wind turbines include a gearbox to increase the speed of the rotor shaft to the required high speed of the generator thus reduce its size and weight. The motivation for direct drive train is to simplify the design and to improve reliability without using gearbox; although there are considerable challenges in designing direct drivetrain that is lighter or more cost‐effective than the conventional geared drive trains.
What are the most commonly used generator types for variable‐speed operation of wind turbine? What PMSG, WRIG, and SQIG stand for?
Synchronous generator and induction generator are two most commonly used generator types for variable‐speed operation of wind turbines. PMSG: Permanent Magnet Synchronous Generator; WRIG: Wound Rotor Induction Generators; SQIG: Squirrel Cage Induction Generator.
What are the advantages of WRIGs when compared with other types of generators?
A Wound Rotor Induction Generator (WRIG) consists of stator and rotor both having windings of copper wire; rotor windings are accessible via brushes and slip rings. Power can either be extracted or injected into the rotor via the brushes and slip rings of a WRIG. WRIGs are compact
and fairly rugged (except for the brushes and slip rings) and are less expensive than SGs, but more expensive than SQIGs.
What is the drivetrain design configuration using DFIG? Illustrate the drivetrain design with a sketch.
A drivetrain using DFIG (Doubly Fed Induction
Generator) has the ability to transfer power into or out
of the rotor, as well as out of the stator. This configuration allows a range of operating speed of the induction generator, from approximately 50% below synchronous speed to 50% above.
A wind turbine is to be designed by using a generator with synchronous speed 1800 rpm; rated wind speed 16 m/s. Consider two design options, sketch the power curve for each design by using the Power vs. Rotor speed curves provided: Design 1 – using variable rotor speed to tracking the optimum tip speed ratio ;Design 2 – using fixed rotor speed and gearbox ratio is 1:128.6.
: Power will be regulated at the rated power when wind speed reaches its rated value of 16 m/s so only the part of power curve at or below 16 m/s is shown in the answer below. The Power vs. Rotor spend curves can be used to derive the power curves (Power vs. Wind speed) for two
designs considered.
Design 1: operates at variable rotor speed when wind speed varies, tracking the optimum tip speed ratio to ensure the WT operates at its maximum power coefficient cp; the power curve can be obtained from the maximum power values at various wind speeds, the rated power 5.25MW;
Design 2: the gearbox speed‐up ratio 1:128.6, the generator synchronous speed is 1800 rpm. WT operates at a fixed rotor speed 14 rpm; the power curve can be obtained from the power values at
rotor speed of 14 rpm at various wind speed as shown, rated power 3.0MW.
