| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系所 === 97 === The thesis is to study the characteristics of transient state and steady state of power supply system and grounding system with respect to high voltage grounding faults in the high-tech plaints supplied by 161kV power, and to analyze the harmonic characteristics during normal operation and assess their affections. The circuit model is first constructed by using the electromagnetic transient program/ alternative transient program (EMTP/ATP), in which the very high voltage (VHV) substations, main transformers, high voltage cables, down-stream system loads and each equipment grounding lines are considered. The model is used to analyze the characteristics of transient state and steady state of single-phase ground fault. Three fault points, namely, the second of main transformer, down-stream high voltage bus, and the primary of a step-up transformer of back-up power system are analyzed, besides, the conditions of with and without back-up power system interconnected, down-stream load included harmonic current sources are also considered. Based on the simulation results, the fault currents injected into grounding system at fault points are obtained and the electromagnetic characteristics values of ground grids are further analysis. Finally, a software package for grounding system analysis, namely, CDEGS(Current Distribution Electromagnetic Grounding and Soil Structure Analysis) are used, from which we can find the distribution of ground potential rise (GPR), potential on the ground surface, touch voltage, step voltage, conductor current and electromagnetic field (EMF) on the ground surface. All the electromagnetic characteristics of grounding system for both case of with and without interconnection between main ground grid and down-stream ground grid are analyzed and compared. Then based on the above analysis results, the affections on personnel, equipments and systems are evaluated.
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