ABSTRACT
The
flexible ac-transmission system (FACTS) family called distributed power flow
controller (DPFC). The DPFC is derived from the unified power flow controller
(UPFC) with eliminated common dc link. The active power exchange between the
shunt and series converters, which is through the common dc link in the UPFC,
is now through the transmission lines at the third harmonic frequency. The DPFC
is to use multiple small size single phase converters instead of large size
three phase series converter in the UPFC. The large number of series converters
provides redundancy, thereby increasing the system reliability. As the D-FACTS
converters are single phase and floating with respect to the ground, there is
no high voltage isolation required between the phases. The cost of the DPFC
system is lower than the UPFC. The DPFC has the same control capability as the
UPFC, which comprises the adjustment of the line impedance, the transmission
angle, and the bus voltage. Due to the high control capability DPFC can also be
used to improve the power quality and system stability, such as low frequency power
oscillation damping, voltage sag restoration or balancing asymmetry.
KEYWORDS
1.
AC–DC power conversion
2.
Load flow control
3.
Power electronics
4.
Power semiconductor devices
5.
Power system control
6.
Power-transmission control
SOFTWARE:
MATLAB/SIMULINK
BLOCK
DIAGRAM:
Figure
1.DPFC configuration
EXPECTED SIMULATION RESULTS
Figure
2.Supply voltage during sag condition
Figure
3. Injected voltage during sag condition
Figure
4. Elimination of sag voltage
Figure
5. Supply voltage during swell
Figure
6. Injected voltage for swell
Figure
7. Elimination of swell voltage
CONCLUSION
The
series converter of the DPFC employs the DFACTS concept, which uses multiple
small single-phase converters instead of one large-size converter. It is proved
that the shunt and series converters in the DPFC can exchange active power at
the third-harmonic frequency, and the series converters are able to inject
controllable active and reactive power at the fundamental frequency. The DPFC
is also used to improving power quality problems such as sag and swell. The reliability
of the DPFC is greatly increased because of the redundancy of the series
converters. The total cost of the DPFC is also much lower than the UPFC,
because no high-voltage isolation is required at the series converter part and
the rating of the components of is low.
REFERENCES
[1]
D. Divan and H. Johal, “Distributed facts-A new concept for realizing grid
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8–14.
[2]
K K. Sen, “Sssc-static synchronous series compensator: Theory, modeling, and
application”,IEEE Trans. Power Del., vol. 13, no. 1, pp 241–246, Jan. 1998.
[3]
L.Gyugyi, C.D. Schauder, S. L.Williams, T. R. Rietman, D. R. Torgerson, and A.
Edris, “The unified power flow controller: A new approach to power transmission
control”, IEEE Trans. Power Del., vol. 10, no. 2, pp. 1085– 1097, Apr. 1995.
[4]
M. D. Deepak, E. B. William, S. S. Robert, K. Bill, W. G. Randal, T. B. Dale,
R. I. Michael, and S. G. Ian, “A distributed static series compensator system
for realizing active power flow control on existing power lines”, IEEE Trans.
Power Del., vol. 22, no. 1, pp. 642–649, Jan.2007.
[5]
M. Mohaddes, A. M. Gole, and S. Elez, “Steady state frequency response of
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