ISSN 10683712, Russian Electrical Engineering, 2013, Vol. 84, No. 10, pp. 577–580. © Allerton Press, Inc., 2013.
Original Russian Text © I.M. Kirpichnikova, A.S. Mart’yanov, E.V. Solomin, 2013, published in Elektrotekhnika, 2013, No. 10, pp. 46–50.
Generators are used as converters of mechanical
energy into electrical energy in windpower units
(WPUs). In addition to the general requirements, a series
of special requirements are imposed on generators,
which reflects the specificity of their work, which mainly
is that they are driven by a wind wheel, the modes of
operation and, above all, the speed modes of which are
determined by the speed of the wind and are inconstant.
Windpowerunit generators are designed to operate
in a wide range of rotation frequencies, which reduces
their use in comparison with generators rated at con
stant rotation frequency. The generator load is also vari
able. It is formed by the power and number of consum
ers connected at a point in time that depends on the
connected equipment, modes of operation, time of
year, time of day, and condition of accumulator battery.
The output voltage of the generator must be stable
at a variable rotation frequency and variable load.
Therefore, most generators operate with voltage regu
lators that maintain the output voltage. Regulation of
voltage for generators with electromagnetic excitation
is carried out by varying the excitation current of the
generator; at the same time, the excitation current
should not be greater than that allowed for selected
types of voltage regulators.
The generator should be protected from overloads.
The limiting load of the generator is determined by the
heating of the generator itself and voltage rectifiers and
regulators built into it. Generators must have selflim
itation to ensure that the maximum current does not
exceed the value allowed by heating at any speed.
Analysis of known types of generators for wind
power units, along with determination of their charac
teristics, shows that each type of generator structure
has advantages and disadvantages. For example, when
using permanent magnets for generator excitation, the
obvious advantage is the lack of a need for supplying
power to excitation windings and, as a consequence, a
lack of electrical losses during excitation. Use of elec
tromagnetic excitation makes it possible to adjust the
output voltage by the excitation circuit, but there are
electrical losses upon excitation and a sliding contact
(noncontact designs are much more complicated than
designs with contact rings).
It is known that, in electric machines much of the
generated power in unfavorable regimes is used for elec
tromagnetic excitation, which leads to a decrease in the
efficiency of a machine with this type of excitation. This
is because, at a low rotation frequency, when the excita
tion winding should compensate the decrease of rota
tion frequency by increasing the magnetic flux, the effi
ciency of the generator will be even lower, because an
even greater part of the generated energy will be used for
excitation instead of being assigned to the load. Prob
lems concerning cooling of the exciting winding can
arise when using electromagnetic excitation, so using
permanent magnets is most preferred.
Based on an analysis that was carried out of possible
structures, an ac synchronous electric permanentmag
net machine with a longitudinal (axial) gap or “valve
generator” has been selected as a WPU for incorpora
tion into the structure of a windpowerunit hub.
Development and optimization of the generator
and the electronic system of the WPU have their own
peculiarities related to the fact that fullscale (field)
testing is technically difficult and unprofitable from
the economic point of view. These circumstances force
designers to use stateoftheart engineering technol
ogies during designing and testing of these devices,
which reduces the total costs during the design and
production of samples. Mathematical modeling is one
way to solve this problem. At the stage of engineering
development, solid modeling in CAD systems such as
SolidWorks significantly speeds up the engineering
time for generator construction. For electromagnetic
and thermal design, one can apply the finiteelement
method using the EMAG software package Ansys.
Simulation of a Generator for a WindPower Unit
I. M. Kirpichnikova
, A. S. Mart’yanov
, and E. V. Solomin
South Ural State University, Chelyabinsk, 454080 Russia
Received September 16, 2013
—Analysis of excitation systems of generators for windpower units is carried out, a software package
for generator simulation is presented, and the sequence of the generator design is presented.
: winddriven electric plant, generator, simulation, optimization
The original version of this article was revised: A previously
missing affiliation was added.