ABSTRACT:
During the last two decades, the operation of power systems
has become complex due to growing consumption and increased number of
non-linear loads because of which compensation of multiple power quality issues
has become an compulsion. A new component within the flexible AC-transmission
system (FACTS) family, called distributed Power-flow controller (DPFC) is
presented in this paper.
The DPFC is derived from the unified power-flow controller
(UPFC). The DPFC can be considered as a UPFC with an 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 employs the distributed FACTS (DFACTS) concept,
which is to use multiple small-size single-phase converters instead of the one
large-size three-phase series converter in the UPFC. Power quality issues are
studied and DPFC is used to mitigate the voltage deviation and improve power
quality. In this paper, the capability of DPFC is observed for the transmission
line based on PI and fuzzy logic controllers (FLC). On comparing the two
controllers performance, we can say that Fuzzy Logic Controller based DPFC
gives better compensation than PI Controller based DPFC. Matlab/Simulink is
used to create the PI and FLC and to simulate DPFC model.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig 1 The DPFC Structure
EXPECTED SIMULATION RESULTS:
Fig 2 Voltage Sag without DPFC
Fig 3 Current Swell without DPFC
Fig 4 THD without DPFC
Fig 5 Voltage sag Compensation with DPFC using PI Controller
Fig 6 Current Swell Compensation with DPFC using PI
Controller
Fig 7 THD with DPFC using PI Controller
Fig: 8 Voltage Sag Compensation with DPFC using Fuzzy Logic
Controller
Fig: 9 Current Swell Compensation with DPFC using
Fuzzy Logic Controller
Fig 10 THD with DPFC using Fuzzy Logic Controller
CONCLUSION:
This paper has presented mitigation of various power
quality issues like voltage sag and swell by employing a new FACTS device
called Distributed Power Flow Controller(DPFC).
The DPFC .is emerged from the UPFC and inherits the
control capability of the UPFC, which is the simultaneous adjustment of the
line impedance, the transmission angle, and the bus voltage magnitude.
The common dc link between the shunt and series
converters, which is used for exchanging active power in the UPFC, is
eliminated.
This power is now transmitted through the transmission
line at the third harmonic frequency.
The series converter of the DPFC employs the D FACTS
concept, which uses multiple small single phase converters instead of one large
size converter. 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.
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.
Also the performance of DPFC is simulated using two
mechanisms i.e., with PI and Fuzzy controllers Simulation is also carried
without these two controllers.
In this case study three phase fault is injected into
the system near the load and the results prove that the DPFC with Fuzzy
controller gives better voltage compensation than DPFC with PI controller.
REFERENCES:
(1)
Zhihui Yuan, Sjoerd W.H de Haan, Braham Frreira and Dalibor Cevoric “A FACTS
Device: Distributed Power Flow Controller (DPFC)” IEEE Transaction on Power
Electronics, vol.25, no.10,October 2010.
(2) 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”. Power Delivery, IEEE Transactions on,
1995.
(3) Y. H. Song and A. Johns. Flexible ac transmission systems
(FACTS). Institution of Electrical Engineers, 1999.
(4) " Power quality improvement and Mitigation
case study using Distributed Power Flow Controller "Ahmad Jamshidi
,S.Masoud Barakati and Mohammad Moradi Ghahderijani,IEEE Transactions on,2012
(5) N.G.Hingorani and L.Gyugyi, Understanding FACTS,
Concepts and Technology of Flexible AC Transmission Systems. Piscataway, NJ:
IEEE Press 2000
