ABSTRACT:
This paper
presents a novel control strategy for the operation of a direct drive permanent
magnet synchronous generator (PMSG) based stand alone variable speed wind
turbine. The control strategy for the generator side converter with maximum
power extraction is discussed. The stand alone control is featured with output voltage
and frequency controller capable of handling variable load. The potential
excess of power is dissipated in the damp resistor with the chopper control and
the dc link voltage is maintained. Dynamic representation of dc bus and small
signal analysis are presented. Simulation results show that the controllers can
extract maximum power and regulate the voltage and frequency under varying wind
and load conditions. The controller shows very good dynamic and steady state performance.
KEYWORDS:
1.
Permanent magnet synchronous generator
2.
Maximum power extraction
3.
Switch-mode rectifier
4.
Variable speed
5.
Wind turbine
6.
Voltage and frequency control
SOFTWARE: MATLAB/SIMULINK
Figure
2. Response of the system for a step change of wind speed from 10 m/s
to
12 m/s to 9 m/s to 10 m/s.
Figure
3. Optimum torque and generator torque.
Figure
4. Turbine mechanical input power and Electrical output power.
Figure
5. Voltage and current responses at a constant load.
Figure
6. Frequency response, DC link voltage and modulation index at
a
constant load.
Figure
7. Voltage and current responses when load is reduced by 50%.
Figure
8. Frequency response, DC link voltage and modulation index when load is
reduced by 50%.
CONCLUSION:
Control strategy for a direct drive
stand alone variable speed wind turbine with a PMSG is presented in this paper.
A simple control strategy for the generator side converter to extract maximum
power is discussed and implemented using Simpower dynamic system simulation
software. The controller is capable to maximize output of the variable speed
wind turbine under fluctuating wind. The load side PWM inverter is controlled
using vector control scheme to maintain the amplitude and frequency of the inverter
output voltage. It is seen that the controller can maintain the load voltage
and frequency quite well at constant load and under varying load condition. The
generating system with the proposed control strategy is suitable for a small scale
standalone variable speed wind turbine installation for remote area power
supply. The simulation results demonstrate that the controller works very well
and shows very good dynamic and steady state performance.
REFERENCES:
[1] Müller, S., Deicke, M., and De
Doncker, Rik W.: ‘Doubly fed induction genertaor system for wind turbines’,
IEEE Industry Applications Magazine, May/June, 2002, pp. 26-33.
[2] Polinder H., Van der Pijl F. F. A,
de Vilder G. J., Tavner P. J.: "Comparison
of direct-drive and geared generator concepts for wind turbines," IEEE
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[3] Chan T. F., and Lai L. L., "Permanenet-magnet
machines for distributed generation: a review," Proc. IEEE power
engineering annual meeting, 2007, pp. 1-6.
[4] De Broe M., Drouilhet S., and
Gevorgian V.: “A peak power tracker for small wind turbines in battery charging
applications,” IEEE Trans. Energy Convers. 1999, 14, (4), pp. 1630–1635.
[5] Datta R., and Ranganathan V. T.: “A
method of tracking the peak power points for a variable speed wind energy
conversion system,” IEEE Trans. Energy Convers., 1999, 18, (1), pp. 163–168.
