this is useful for the b.tech engineering students

1. Solar and wind energy
Topic:- fixed and variable speed wind
turbine
by
Sonu kumar bairwa

2. Fixed speed wind turbine
• A fixed-speed wind turbine always spins at the
same generator/rotor speed during operation,
regardless of the wind speed.
• Thus, the tip-speed ratio (TSR) would change
with wind speed and the rotor aerodynamic
performance would only be optimal at a given
wind speed.
• The generator torque of a fixed-speed wind is
dictated solely by the induction generator.

3. • that the fixed-speed turbine actually has a
small variation in generator speed, so that
large variations in wind speed result in small
variations in generator speed and large
variations in torque / power i.e. the torque-
speed curve is steep.
• The power grid operates at a "fixed
frequency", so, coupling a fixed-speed turbine
to the grid is straightforward.
• Coupling a variable-speed turbine to the grid
requires a fancy power electronics i.e. AC-to-
DC-to-AC conversion

5. • FSWTs are equipped with an induction
generator (squirrel cage or wound rotor) that
is directly connected to the grid via a
transformer, with a soft-starter and a
capacitor bank for reducing reactive power
compensation.
• They are designed to achieve maximum
efficiency at one particular wind speed.
• In general, two control strategies have been
used with FSWT: Active stall control and pitch
control.

6. scSICG-squirrel cage induction generator
The connection with the grid is controlled by a soft-starter and a bank of capacitors.

7. variable speed wind turbine
• A variable-speed wind turbine allows the
generator/rotor speed to vary proportional to
wind speed between cut-in and rated speed,
thus maintaining a constant TSR and optimal
aerodynamic performance.
• Above rated speed, the generator/rotor speed
is then held constant. The torque must be
actively controlled.