| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 87 === With the rapid development of the power electronic techniques, the nonlinear devices, especially static power converters, have been widely used in industry. The harmonic currents, which are generated by nonlinear devices, inject into the power system and result in voltage distortion. Furthermore, with the increasing use of static power capacitor, which is used for improving power factor, can induce a great number of resonant frequencies and there is much risk of harmonic pollution. In order to perceive the distortion in voltage and current waveforms at various points in power distribution system and identify whether any potentially harmful resonance conditions exist, harmonic analyses have become an essential part of power distribution system at planning, design, and operation stages. Firstly, the thesis will discuss the cause of harmonics and the resultant effects of power system harmonics on equipment. Then, a general harmonic model of nonlinear device by means of "Cross Frequency Admittance Matrix" (CFAM model) is derived from experiment and used to replace the current source model for subsequent analysis. The salient feature of CFAM model lies in that it can take into account the interactions between harmonic voltages and currents. Finally, incorporating the aforementioned harmonic model with an iteration algorithm, a software package for harmonic analysis is developed. Simulation results performed for two different distribution systems are compared with actual field measurements. It shows that the proposed method is superior to the conventional current injection method in accuracy improvement.
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