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154 Doru Calarasu et al.
2. Constructive-Operational Description
A wind power plant turns wind energy into mechanical power. The chosen
solution refers to very low power (500 – 1000 W) wind turbines.
When the wind speed does not exceed a certain speed limit, the rotor
assembly does not tilt. The propeller rotates at an angular speed, which depends
on the wind speed and on the mechanical output load.
When the wind speed reaches or exceeds the speed limit, the rotor assembly
tilts and the propeller changes its rotation plane.
HAWT
Damping
device
Protection
mechanism
Tilting
device
Fig. 1 – Constructive block diagram.
Balancing
device
Thanks to its components (Fig. 1), this mechanical-hydraulic protection
mechanism also ensures the operation of the wind turbine at wind speeds higher
than the rating speed, having the following functions:
a) the rotor assembly is directed towards the wind stream using the
mechanism’s lower bearing, by means of which the assembly is placed on the
support pillar;
b) the tilting device becomes active when the wind speed exceeds the safety
limit and it reduces the active turbine surface exposed to the wind;
c) the balancing device ensures stable balance to the wind turbine rotor at wind
speeds lower than the safety limit and unstable balance when the wind speed
reaches the safety limit;
d) the damping device protects the plant against wind gusts by delaying the
propeller’s resuming its initial position.
3. Digital Simulation Tests performed on the Conceptual Model of
Mechanical-Hydraulic Protection Mechanisms
The Matlab-Simulink programming environment was used for the
performance of the digital simulations.