| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系研究所 === 98 === The thesis is to study the characteristics of transient and steady state of high and low voltage systems with respect to grounding faults in the Large High-Tech industrial plants, 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 high voltage(HV) substations, high voltage transformers, high and low voltage cables, down-stream loads, each equipment grounding and neutral lines are considered. The model is used to analyze the characteristics of transient state and steady state of single-phase ground fault. The fault are at the primary side of high voltage transformer, backup power supply bus, down-stream load bus, and each down-stream single-phase and three-phase loads. The conditions of with and without backup power supply 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 analyzed. Finally, a software package for grounding system analysis, namely, CDEGS(Current Distribution Electromagnetic Grounding and Soil Structure Analysis) are used, for the analysis of 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 each ground grids are analyzed and compared. Then based on the above analysis results, the affections on personnel, equipments and systems are evaluated.
|
|---|
