05-05-2011, 02:31 PM
Abstract -
The proliferation of power electronic
based equipment has produced a significant impact
on the quality of electrical power supply. The
modern day equipments are highly sensitive to
deviation from ideal sinusoidal voltages.
Conventional power quality enhancement
equipments are providing to be in adequate. A very
promising solution for supply voltage imperfection
is UPQC (Unified Power Quality Conditioner).
Unified power quality conditioners (UPQCs) allow
the mitigation of voltage and current disturbances
that could affect sensitive electrical loads while
compensating the load reactive power. In this Paper
We deal with implementation of left shunt
configuration UPQC for voltage sag mitigation. The
solution is proved using MATLAB 7.5.
Index Terms—Custom power device, FACTS, DVR,
STATCOM, Series Injection, Shunt Injection,
Power Quality.
I. OVERVIEWOF POWER QUALITY PROBLEMS
Any problem manifested in voltage, current or
frequency deviation that results in failure of customer
equipment is known as power quality problem.
Low power quality affects electricity consumer in
many ways. The lack of quality can cause loss of
production, damage to equipment and human health.
Therefore it is obvious to maintain high standards of
power quality.
The major types of power quality problems are,
• Voltage Sag
• Voltage swell
• Interruption
• Distortion and
• Harmonics.
A. Interruption:
An Interruption occurs when the supply voltage or
load current decreases to less than 0.1 pu for a period of
time that is not exceeding 1 min. Interruptions can be
the result of power system faults, equipment failures
and control malfunction. Instantaneous re-closing
generally will limit the temporary fault to less than 30
cycles.
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