ABSTRACT:
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 concept, in which the common
dc-link between the shunt and series converters are eliminated and three-phase
series converter is divided to several single-phase series distributed
converters through the line. According to the growth of electricity demand and
the increased number of non-linear loads in power grids harmonics, voltage sag
and swell are the major power quality problems. DPFC is used to mitigate the
voltage deviation and improve power quality. Simulations are carried out in
MATLAB/Simulink environment. The presented simulation results validate the DPFC
ability to improve the power quality.
KEYWORDS:
1. Load
flow control
2. FACTS
3. Power
Quality
4. Harmonics
5. Sag
and Swell Mitigation
6. Distributed Power Flow Controller
7. Y–Δ transformer
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. DPFC configuration
EXPECTED SIMULATION RESULTS:
Fig 2. three phase voltage
sag waveform without DPFC
Fig. 3 three phase voltage
sag waveform with DPFC
Fig.4 3-ϕ load current swell
waveform without DPFC
Fig.5 Mitigation of 3-ϕ load current
swell with DPFC
Fig.6 Total harmonic
distortion of load voltage without DPFC
.
Fig.7 Total harmonic
distortion of load voltage with DPFC
CONCLUSION:
This paper has presented a new concept called DPFC. The
DPFC emerges 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 DFACTS 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. To
improve power quality in the power transmission system, the harmonics due to
nonlinear loads, voltage sag and swell are mitigated. To simulate the dynamic performance,
a three-phase fault is considered near the load. It is shown that the DPFC
gives an acceptable performance in power quality improvement and power flow
control.
REFERENCES:
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[3] Zhihui Yuan, Sjoerd W.H de Haan and Braham Frreira “DPFC control during
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