本研究主要分析捷運雙邊供電系統及接地系統於發生接地故障時之暫態與穩態特性,以及平時運轉、故障時之諧波特性並評估其影響,其中考慮軌道採用二極體接地及非接地兩種情況。首先應用電磁暫態分析軟體(EMTP/ATP)建構電路模型,模型涵蓋22.8kV高壓變電站、整流變壓器、高壓電纜、二極體、避雷器、第三軌、行車鋼軌及各種設備接地線等,並使用此模型分析單相接地故障之暫態與穩態特性,其中故障位置分別考慮整流變壓器一次側(22kV)、整流變壓器二次側(588V)及行車鋼軌等三種情況,本文中另外有考慮第三軌與行車鋼軌間之短路故障並加以分析。藉由上述分析所得注入地網之各點故障電流,將這些故障電流注入接地系統分析軟體(CDEGS)所建構之等效地網來模擬地網電磁暫態及穩態特性,包括地電位昇(GPR)、地表電位、接觸電壓、步間電壓、導體電流及地表電磁場之分佈狀況,其中各地網間互連之情形亦加以比較差異,藉由上述分析結果,最後評估可能發生之風險包括對於人員與設備所受的影響。
The thesis is to study the characteristics of transient state and steady state of power supply system and grounding system with respect to grounding faults in the Rapid Transit System (RTS) supplied by double-side source, and to analyze the harmonic characteristics during normal operation and fault occurrence. Two cases of diode grounded and ungrounded for rails are considered and their affections assessed. The circuit model is first constructed by electromagnetic transient program/ alternative transient program (EMTP/ATP), in which the high voltage (22.8kV) substations, rectifier transformers, high voltage cables, diodes, surge arresters, third rail, running rail and each equipment grounding lines are considered. The model is used to analyze the characteristics of transient state and steady state of single-phase grounding fault, and three fault points are considered, that are primary of rectifier transformer, the second of rectifier transformer and running rail ,respectively, and the short fault between the third rail and running rail is also considered. Based on the above simulation results, the fault currents are obtained and injected them into the fault points of the grounding system, which is constructed by CDEGS(Current Distribution Electromagnetic Grounding and Soil Structure Analysis), to analysis electromagnetic characteristics of steady state and transient state in ground grids, including distribution of ground potential rise (GPR), potential on the ground surface, touch voltage, step voltage, conductor current and electromagnetic field (EMF). All the electromagnetic characteristics of grounding system for both cases 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.