| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系研究所 === 102 === Nowadays, most of home-use electrical appliances are electronic products which usually have the advantages of multifunction and small size, but their capability to withstand the impacts of lightning and switching surges is usually low. Consequently,damage cases in the low voltage customers due to lightning and switching surges from feeder are frequent. In the thesis, the characteristics of lightning and switching surges of secondary substation and feeders are analyzed, and the surge voltages from feeder to low voltage customers are surveyed and the affections are evaluated.
First of all, Modeling based on the alternative transient program (ATP) of electromagnetic transient program (EMTP) for secondary substation and the downstream feeders are presented. Then, the voltages at low voltage customer during various types of lightning and switching at substation and feeder are analyzed based on ATP simulations. For lightning surge simulation, different lightning points with different lightning strengths are considered. Also, for the switching surge simulation, the switch close and open operations at primary and secondary sides of substation and at the feeder under synchronous and non-synchronous operation are considered.
Finally, the affections of lightning and switching surges on the low voltage customer will be assessed based on the comparisons between the simulation results and the surge voltage tolerances of low voltage equipments specified by IEC standard. The assessment results show that malfunction may be occurred on the sensitive equipments in low voltage customers due to surge voltage from the switch non-synchronous close operation, while various equipments will suffer form damages due to lightning on the nearby feeder. Thus, more attention should be given to the surge protection issues for low voltage customer, and the study can provide related information and numerical date.
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