Distributed control of a nine phase permanent magnet PO ... J.R. and Miller, T.J.E., Design of...
Transcript of Distributed control of a nine phase permanent magnet PO ... J.R. and Miller, T.J.E., Design of...
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ACKNOWLEDGEMENTS
This study was supported by the Spanish Ministerio de Economía y Competitividad under the project
ENE2012-33043
First, a the detailed mathematical model of the multiphase machine, assuming non-
zero mutual couplings between the three stators [3-6] is developed. Once the model
is defined, the current controller of the machine is designed based on the obtained
system equations, considering that no communications are available between the
different stator controllers. For this reason, the torque control is divided in three
independent controllers, each performed by the converter connected to each stator.
Each converter carries out its own controller in the machine reference frame,
regulating the active and reactive current flowing through its circuit. The controllers
are designed to show a reduced interaction between the stators during the
operation.
A distributed torque control of a nine-phase wind turbine generator is proposed in
this paper. Specifically, the generator is compounded by three different three-phase
stators embedded in the same machine yoke. Due to this configuration, the
machine couplings between stators are present during the operation [1], fact that
complicates the design of the current controllers. Multiphase machines usually
require a centralized controller to achieve a good performance during the operation
[2]. However, the control proposal presented here deals with the implementation of
a decentralized controller, considering that each stator only knows its own
measurements, in order to increase the machine operation possibilities.
Different simulations and experiments have been performed to test the behavior
of the machine distributed current control, considering different possible
scenarios. These tests have validated the concept viability and the controller
design methodology with satisfactory results. These experiments also have
shown that a triple three-phase permanent magnet generator configuration, along
with the designed controller, could be an interesting proposal to be installed in
future offshore wind power plants, because it has additional capabilities in
comparison with the classical three-phase structures, in terms of redundancy,
fault operation and control possibilities.
Abstract
Distributed control of a nine phase permanent magnet
generator and scaled platform validationE. Prieto-Araujoa / D. Lavèrniab / A. Junyent-Ferréc / O. Gomis-Bellmunta,b
aCITCEA-UPC / bIREC / cC&P Imperial College
PO. ID
338
Experimental results
Control design methodology
Conclusions
Simulations
References
EWEA 2014, Barcelona, Spain: Europe’s Premier Wind Energy Event
To validate the controller, a simulation model representing the operation of a nine-
phase wind turbine generator has been developed. The simulated scenario
consists on introducing a step change to the active current reference of the stator 1
(q axis), to observe the performance of the controller of this stator along with the
interaction between stators.
Summary
Magnitude -
𝑖𝑠1𝑞∗
reference 0 to 500 A - 0.5 s.
𝑖𝑠1𝑑∗reference Constant at 0 A
𝑖𝑠2𝑞∗
reference Constant at 0 A
𝑖𝑠2𝑑∗reference Constant at 0 A
𝑖𝑠3𝑞∗
reference Constant at 0 A
𝑖𝑠3𝑑∗reference Constant at 0 A
Controllers
time response
10 ms
Speed Constant (rated)
The controller shows a good
performance during the current step
change. The time response defined
during the controller design stage is
accomplished because the stator 1
active current reaches the steady
state in 10 ms. Also, as the
controllers do not compensate the
effects between stators, currents of
stators 2 and 3 are affected by the
current change in stator one.
However, these effects are
compensated in a few milliseconds
by their respective controllers.
The control algorithms have been
validated in a scaled wind turbine test
rig. This rig is composed by two 30
kW permanent magnet machines,
one acting as a motor and the other
as a generator, joined mechanically
by their axes. The motor is connected
to a frequency converter and the
generator is a nine-phase generator
with three independent stators,
connected to the grid by means of
three back-to-back converters.
Two different experiments are performed to show the behavior of the designed
controller. The first test is performed to validate the decentralized controller of
the machine, setting the active current reference of the three stators to the same
value. Then a second experiment is developed to validate that the current
regulator is able to operate the machine with different current references for
each stator. The results shown below have validated the performance of the
controller during the developed experiments.
Machine phase ‘a’
current waveforms
flowing through each
of the machine
stators during the
experimental tests.