| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 89 === The three phases four wires 220/380V grounded Y connected con-figuration is mostly used for low voltage distribution system in Taiwan. Meanwhile the three phases four wires 110/220 V-V connected configu-ration is widely used for commercial and residencial regions to supply single phase home appliances and other equipments. The electrical engi-neers were used to design low voltage distribution system with reducing the rating of the neutral wire based on the considerations that electric loads were distributed evenly and the unbalance condition was not very serious.
Recently, a large number of power electronic control equipments were used in industrial applications, the current harmonic contents became to be the major concerns affect the power quality of the distribution sys-tems and the electric safety. It may cause electric fire hazards when the total current flowing in the neutral wire exceeds the rated ampacity of the neutral wire. The research was devoted to discuss the effects and harmfulness due to current harmonics caused by higher harmonic loads in the distribution system. The various connections model of the dis-tribution transformer and Y/ connected configurations of the loads were proposed firstly, then we simulate and analyze the effects caused by current harmonics by Pspice, a commercial simulation software, in order to evaluate the distribution safety quantitively. Finally, many strategies were proposed to solve the current harmonics problems caused by lighting luminaries as an example to discuss the effectiveness of the strategies proposed.
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