Environmental Engineering Reference
In-Depth Information
length of warranty period the quantity of controllers in need
of repair would not be sustainable.
While continuing shipping Turbine with controller of known
deficiencies and repairing under warranty any damage to it as well
as improving Turbine mechanics where needs arose, Company
started designing a new controller. This time it relied on in-house
expertise. It was not a modification of the original controller,
as incremental changes wouldn't do. Interaction with Turbine
customers and analyses of their problems brought in new ideas,
some of them were not short of leap for the wind industry.
Company had good understanding of customer needs, turbine
physics, ability of modern electronics—firm base for a solid design
of new controller.
The power circuit was considerably simplified; Schottky
diodes took place of MOSFET transistors where that was practical.
The control algorithm became more sophisticated and included
several modes, some unique at the time of introduction.
The following description of Turbine operational modes
should give the reader an idea of what the modern residential scale
turbine is capable of. Here they are explained on Turbine example,
that is, with battery-charging application in mind. For grid-
tie operation in the description below the DC link in AC-DC-AC
converter has to take place of the battery voltage, active front-
end—the diode rectifier and shorting transistor, and grid—the
battery; there is no need for slow mode in the grid tie.
26.5 
Normal Operation—Peak Power Tracking
The controller loads turbine such a way that the rotational
speed of blades is optimal for the given wind velocity from the
perspectives of maximal power taken from the wind and eventually
converted to the electrical energy consumed by loads or/and stored
by batteries. The controller sets the rotational speed of turbine
by creating the voltage on turbine output. That comes as a result
of turbine physics. The controller creates a voltage on its input by
very fast connecting turbine output to the battery and then shorting
the turbine (boost) or disconnecting the turbine (buck). This
connect-short or connect-disconnect cycle is repeated many
thousand times per second, so only average values become
meaningful. For the boost the voltage on the input of controller
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