ABSTRACT
Present energy
need heavily relies on the conventional sources. But the limited availability
and steady increase in the price of conventional sources has shifted the focus
toward renewable sources of energy. Of the available alternative sources of
energy, wind energy is considered to be one of the proven technologies. With a
competitive cost for electricity generation, wind energy conversion system
(WECS) is nowadays deployed formeeting both grid-connected and stand-alone load
demands. However, wind flow by nature is intermittent. In order to ensure
continuous supply of power suitable storage technology is used as backup. In
this paper, the sustainability of a 4-kW hybrid of wind and battery system is
investigated for meeting the requirements of a 3-kW stand-alone dc load
representing a base telecom station. A charge controller for battery bank based
on turbine maximum power point tracking and battery state of charge is
developed to ensure controlled charging and discharging of battery. The
mechanical safety of the WECS is assured by means of pitch control technique.
Both the control schemes are integrated and the efficacy is validated by
testing it with various load and wind profiles in MATLAB/SIMULNIK.
KEYWORDS
1. Maximum power point tracking (MPPT)
2. Pitch control
3. State of charge (SoC)
4. Wind energy conversion system (WECS).
SOFTWARE: Matlab/Simulink
BLOCK DIAGRAM:
Fig.
1. Layout of hybrid wind–battery system for a stand-alone dc load.
SIMULATION RESULTS:
Fig.
2. (a) WT and (b) battery parameters under the influence of gradual variation
of wind speed.
Fig.
3. (a)WT and (b) battery parameters under the influence of step variation of
wind speed.
Fig.
4. (a) WT and (b) battery parameters under the influence of arbitrary variation
of wind speed.
CONCLUSION
The power available from a WECS is very
unreliable in nature. So, a WECS cannot ensure uninterrupted power flow to the
load. In order to meet the load requirement at all instances, suitable storage
device is needed. Therefore, in this paper, a hybrid wind-battery system is
chosen to supply the desired load power. To mitigate the random characteristics
of wind flow the WECS is interfaced with the load by suitable controllers. The
control logic implemented in the hybrid set up includes the charge control of
battery bank using MPPT and pitch control of the WT for assuring electrical and
mechanical safety. The charge controller tracks the maximum power available to
charge the battery bank in a controlled manner. Further it also makes sure that
the batteries discharge current is also within the C/10 limit. The current
programmed control technique inherently protects the buck converter from over
current situation. However, at times due to MPPT control the source power may
be more as compared to the battery and load demand. During the power mismatch
conditions, the pitch action can regulate the pitch angle to reduce the WT
output power in accordance with the total demand. Besides controlling the WT
characteristics, the pitch control logic guarantees that the rectifier voltage
does not lead to an overvoltage situation. The hybrid wind-battery system along
with its control logic is developed in MATLAB/SIMULINK and is tested with
various wind profiles. The outcome of the simulation experiments validates the
improved performance of the system.
REFERENCES
[1]
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[2]
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“Wind energy systems,” Proc. IEEE, vol. 81, no. 3, pp. 378–389, Mar.
1993.
[3]
R. Saidur, M. R. Islam, N. A.
Rahim, and K. H. Solangi, “A review on global wind energy policy,” Renewable
Sustainable Energy Rev., vol. 14, no. 7, pp. 1744–1762, Sep. 2010.
