This paper
presents a control strategy for a standalone wind-energy conversion system
using Permanent Magnet Synchronous Generator (PMSG). The presented control
strategy aims at regulating the load voltage in terms of magnitude and frequency
under different operating conditions including wind speed variation, load
variation and the unbalanced conditions. The wind generating-system under study
consists of a wind turbine, PMSG, uncontrolled rectifier, DC-DC boost converter
and voltage source inverter. The presented control strategy is based firstly
upon controlling the duty cycle of the boost converter in order to convert the
variable input dc-voltage, due to different operating conditions, to an appropriate
constant dc voltage. Hence, a sinusoidal pulse width modulated (SPWM) inverter
is used to regulate the magnitude and frequency of the load voltage via
controlling the modulation index. In order to verify the performance of the employed
wind generating-system, a sample of simulation results is obtained and analyzed.
The presented simulation results show the effectiveness of the employed control
strategy to supply the load at constant voltage and frequency under different
operating conditions.
KEYWORDS:
1.
Wind turbine
2.
PMSG
3.
Voltage and frequency
control
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1.Complete structure of the stand-alone wind-energy conversion system
Fig.
2.Effect of wind-speed variation on the generated voltage and frequency:
a)
Wind speed b) generated line voltage c) frequency of the generated voltage
Fig.
3. DC-link voltage
Fig.
4. Load voltage and current during different periods of wind-speed
variation
a) Effective value of the load voltage b) Instantaneous three-phase
load-current
waveforms
Fig.
5. Effect of load variation on the generated voltage and frequency at
constant
wind speed a) generated line voltage b) frequency of the generated
voltage
Fig.
6. Load voltage and current during different periods of load variations a)
Effective
value of load voltage during different loads b) Instantaneous threephase
load-current
waveforms
Fig.
7. DC Link Voltage during balanced and unbalanced
Fig.
8. Effective value of the load voltage during both balanced and
unbalanced
loading condition
Fig.
9. Load current of each phase during both balanced and unbalanced
loading
conditions (a) Instantaneous waveforms (b) Effective value
CONCLUSION:
This paper has presented a control
strategy of a stand-alone wind-driven Permanent Magnet Synchronous Generator (PMSG)
in order to regulate the magnitude and frequency of the load voltage under
different operating conditions. In order to ensure the validity of the presented
control strategy, the performance characteristics of the wind-generating system
has been studied and discussed under three different operating conditions;
wind-speed variation, load variation and unbalance operating condition. The presented
simulation results have verified the effectiveness of the control strategy to
maintain the load voltage and frequency at a constant level under different
operating conditions. This has been achieved by controlling the duty cycle of
the employed DC-DC boost converter in order to maintain the DC-link voltage
constant at a predetermined value. In addition, the magnitude and frequency of
the load voltage has been maintained constant via controlling the modulation
index of the load-side SPWM inverter. A constant modulation index has been used
in the case of balanced loading conditions. However, different modulation index
for each phase has been used in case of unbalanced loading conditions.
REFERENCES:
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