| dc.description.abstract | Power system harmonic phenomenon was an old problem, but with renewed and unprecedented threat. This matter deserved to get a refreshing look as proliferation of non-linear loads, one of the harmonic sources, has been increasing exponentially
especially at low voltage network. Despite this fact, research into the problem seemed to be declining. Firstly the effect of harmonic current in low voltage, balanced three-phase system has been researched. Cable sizes involved in this study were 2.5 mm2 to 16 mm2. This level of system has been thought to be important since interaction between
users, trained or not, and systems was commonly taken place. Secondly how harmonic
eventually neutral conductor sizing has been studied. It has been confirmed that with the
increased of harmonic content, neutral current value would be increased. In addition,
neutral conductor initial ampacity has been found to be de-rated under the presence of
harmonic. Harmonic derating factor, heating effect method, proposed techniques by
Arthur and Shanahan, followed by Chindris as well as guidelines from IEC and NEC
standards have been identified to be applied to determine the neutral conductor sizing
under harmonic presence. Analysis of results from each method as well as their
performance has been done. Simulation and analysis using Fast Fourier Transform has
been carried out using MATLAB environment. Comparison between each method
including comparison to the basic conductor sizing formulation has also been carried
out. It has been concluded that each method, including those proposed by standards, had
its own shortcomings. By further analysing results from two of the methods, two new
mathematical relationships that correlate harmonic content and neutral conductor sizing
have been developed. One of the two formulations has been identified as the best based
on several criteria. This formula contributes towards correct, faster and shorter step of
determining neutral conductor sizing under harmonic presence. | en_US |
