ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...

2. POWER QUALITY Mustafa İNCİ
2. POWER QUALITY
The term “Power Quality” is defined as “Set of parameters defining the
properties of power quality as delivered to the user in normal operating conditions
in terms of continuity of supply and characteristics of voltage (symmetry,
frequency, magnitude, waveform) in IEC. In IEEE Std. 1100-1 999, “Power Quality”
is defined as “The concept of powering and grounding electronic equipment in a
manner that is suitable to the operation of that equipment in a manner that is suitable
to the operation of that equipment and compatible with the premise wiring system
and other connected equipment (Ise et al., 2000).
Power Quality just meant the ability of utilities to provide electric power
without interruption. However, in recent years, power quality becomes an important
concern to customers as well as utilities and facilities. Customers require higher
quality of power than ever before due to the increase in critical load and electronic
device. Power quality is different from reliability in view of the duration of events it
deals with. It treats very short events with a few cycles or seconds duration. New
power quality problems such as sag, swell, harmonic distortion, unbalance, transient,
and flicker may impact on customer devices, causes malfunctions and cost on lost
production and downtime. These problems should be measured and assessed more
accurately than before (Won et al., 2003).
Recently, an increased number of sensitive loads have been integrated into
the electrical power systems. Consequently, the demand for high power quality and
voltage stability has increased significantly (Meyer et al., 2008). Some basic
criterions for power quality are constant rms value, constant frequency, symmetrical
three-phases, pure sinusoidal wave shape and limited THD. These values should be
kept between limits determined by standards if the power quality level is considered
to be high. Power quality covers several types of problems of electrical supply
and power system disturbances. The cost of power interruptions and disturbances
can be quite high as a result of the important processes controlled and maintained
by the sensitive devices (Dong et al., 2004). Sources and effects of power quality
problems can be summarized as follows in 2.1.
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