- 學位論文
考慮自備電源系統之大型科技廠高壓與低壓系統接地故障及諧波特性分析
Analysis of Ground Fault and Harmonic Characteristics of HV and LV Systems in the Large High-Tech Industrial Plants Considering the Backup Power Supply System
摘要
本研究主要分析大型科技廠內高壓及低壓系統發生接地故障時之暫態與穩態特性，以及平時運轉之諧波特性並評估其影響，首先應用電磁暫態分析軟體(EMTP/ATP)建構電路模型，模型涵蓋高壓變電站等效模型、高壓變壓器、高壓及低壓電纜、下游系統負載以及各種設備中性線及接地線等，並且使用所建構之模型進行分析單相接地故障之暫態與穩態特性，其中故障位置分別為高壓變壓器一次側(22.8kV)、負載匯流排及自備電源系統匯流排，並考慮市電與自備電源系統併聯供電、市電單獨供電及自備電源系統單獨供電三種情況，且負載含有諧波電流。此外，藉由前述分析所得注入接地網之電流，再應用接地系統分析軟體(CDEGS)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，最後將評估可能發生之風險包括對於人員與設備所受的影響。
並列摘要
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.