ABSTRACT:
This paper investigates dynamic modeling, design and
control strategy of a grid-connected photovoltaic (PV)/wind hybrid power
system. The hybrid power system consists of PV station and wind farm that are
integrated through main AC-bus to enhance the system performance. The Maximum
Power Point Tracking (MPPT) technique is applied to both PV station and wind
farm to extract the maximum power from hybrid power system during variation of
the environmental conditions. The modeling and simulation of hybrid power
system have been implemented using Matlab/Simulink software. The effectiveness of
the MPPT technique and control strategy for the hybrid power system is
evaluated during different environmental conditions such as the variations of
solar irradiance and wind speed. The simulation results prove the effectiveness
of the MPPT technique in extraction the maximum power from hybrid power system during
variation of the environmental conditions. Moreover, the hybrid power system
operates at unity power factor since the injected current to the electrical
grid is in phase with the grid voltage. In addition, the control strategy successfully
maintains the grid voltage constant irrespective of the variations of environmental
conditions and the injected power from the hybrid power system.
KEYWORDS:
1.
PV
2.
Wind
3.
Hybrid system
4.
Wind turbine
5.
DFIG
6.
MPPT control
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. The system configuration of PV/wind hybrid power system.
(a) Solar
Irradiance.
(b)
PV array voltage.
(c)
PV array current.
(d)
A derivative of power with respect to voltage (dPpv/dVpv).
Fig.
2. Performance of PV array during the variation of solar irradiance.
(a) PV
DC-link Voltage.
(b)
d-q axis components of injected current from PV station.
(c)
Injected active and reactive power from PV station.
(d)
Grid voltage and injected current from PV station.
(e)
The power factor of the inverter.
(f)
Injected current from PV station.
Fig.
3. Performance of PV station during variation of the solar irradiance.
(a) Wind
speed profile.
(b)
The mechanical torque of wind turbine.
(c)
The DC-bus voltage of DFIG.
(d)
Injected active and reactive power from the wind farm.
(e)
The power factor of the wind farm.
(f)
Injected current from the wind farm.
Fig.
4. Performance of wind farm during variation of the wind speed.
(a) Power
flow between PV station, wind farm, and hybrid power system.
(b)
Injected active and reactive power from the hybrid system.
(c)
PCC-bus voltage.
Fig.
5. Performance of hybrid power system at PCC-bus.
CONCLUSION:
In
this paper, a detailed dynamic modeling, design and control strategy of a
grid-connected PV/wind hybrid power system has been successfully investigated.
The hybrid power system consists of PV station of 1MW rating and a wind farm of
9 MW rating that are integrated through main AC-bus to inject the generated
power and enhance the system performance. The incremental conductance MPPT
technique is applied for the PV station to extract the maximum power during
variation of the solar irradiance. On the other hand, modified MPPT technique
based on mechanical power measurement is implemented to capture the maximum
power from wind farm during variation of the wind speed. The effectiveness of
the MPPT techniques and control strategy for the hybrid power system is
evaluated during different environmental conditions such as the variations of
solar irradiance and wind speed. The simulation results have proven the
validity of the MPPT techniques in extraction the maximum power from hybrid
power system during variation of the environmental conditions. Moreover, the
hybrid power system successfully operates at unity power factor since the injected
reactive power from hybrid power system is equal to zero. Furthermore, the
control strategy successfully maintains the grid voltage constant regardless of
the variations of environmental conditions and the injected power from the hybrid
power system.
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