| Summary: | 碩士 === 國立成功大學 === 電機工程研究所 === 83 === Recently, since electronic equipment, intermittent load,
such as electrical arc furnace, welder, and repetitive
starting of large induction motor are extensively used,
the problem harmonics and flickers become so serious that
the electrical power quality is widely concerned. In order
to solve these problems, the status of harmonic pollution
and voltage fluctu- ation on the electrical feeder must be
accurately realized by proper instruments. Several
commercialized instruments had been developed and applied
to filed measurement. But, most of them can not provide
simultaneous detections of the harmonics and flickers of the
three phase voltages and currents for a feed- er. In this
thesis,the prototype of a microcomputer-based instru- ment
system was proposed to meet the problem. It can be
simultaneously applied to harmonic and flicker
measurements. The hardware architecture of the system
are composed of a personnel computer, a sampling and hold
circuit, an analog-to- digital data acquisition system,
an analog low pass filter, and electrical power signal
transducers ( auxiliary PT and CT), The softwares include data
acquisition, digital signal harmonic and flicker
analyzing, and display programs for interactive and long
trend monitoring. Especially, in flicker surement an
indirect demodulation algorithm was proposed to avoid
the serious leakage effect of the system frequency
deviation. Finally, the prototype on-line tested by use it
to measure the outputs of a harmonic/flicker generator
and the recorded data of a real arc furnace feeder，The
availability of the instrument system was validated during
the test, therefore. it is recommended that an economical
and practical is further developed to facilitate the
promotion of power quality.
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