ABSTRACT:
The Power Quality problems during the last two decades
has been the major concern of the power companies. 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. DPFC is derived from the unified power-flow controller
(UPFC). 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 (D-FACTS)
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. Simulink
models are developed with and without the controllers. The three phase fault is
created near the load. Simulation results show the effectiveness between the
two controllers.
KEYWORDS:
1.
Power Quality
2.
D-FACTS
3.
DPFC
4.
Voltage Sag
5.
Swell
6.
PI Controller
7.
Fuzzy Logic Controller
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:
In this study mitigation of power quality issues like
voltage sag and swell are simulated in Matlab/Simulink environment 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 Logic
controllers.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] Krishna Mohan Tatikonda,N.Swathi,K.Vijay
Kumar"A Fuzzy Control scheme for damping of oscillations in multi machine
system using UPFC" International trends for emerging trends in engineering
and development on September 2012
[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
