电容电流剧增条件下大型发电机定子接地故障分析与优化设计研究

大型发电机定子单相接地故障发生率高，会导致定子铁心烧伤、接地故障发展为相间或匝间短路，危害极大。项目将围绕电容电流剧增条件下大型发电机定子接地故障分析与优化设计展开理论分析和试验研究：1）以真机（定子铁心+线棒）升流燃弧试验为基础，建立定子铁心烧损过程的“电-热”分析模型，进而定量分析试验研究无法考虑因素对定子铁心烧损过程的影响，科学确定定子接地故障安全电流值；2）提出大型发电机组合型接地变优化设计及验证方法，通过不同方式引入电感分量来补偿电容电流，满足接地故障安全电流值的要求并抑制重燃弧暂态过电压；3）提出兼顾定子绕组优化设计的大型发电机定子接地故障定位方法，依据对波绕组发电机分支电势构成特点的分析，将提高定位精度至故障线棒。项目成果将确保大型发电机定子接地故障发生后定子铁心的安全，避免定子铁心返厂检修或重新现场叠片，并准确定位故障线棒，缩短故障检修的时间，具有重大的经济效益和社会效益。

Large generator stator single-phase grounding faults have a high incidence, and it can cause stator core damaged, and may also cause grounding fault to develop into phase-to-phase short circuit or inter-turn short circuit, which are extremely harmful..The project will focus on theoretical analysis and experimental research on the stator grounding fault analysis and optimization design of large generators under the condition that capacitor current is increasing rapidly:.1) Based on the arc damage experiments of the generator (stator core + winding bar), establish an "electric-thermal" analysis model of the stator core damage process, and then quantitatively analyze the effects of factors which cannot be considered in the experimental research on the stator core damage process, and scientifically determine the stator grounding fault safety current;.2) Propose the optimization design and verification method of large generator combined grounding transformer, introduce inductance components in different ways to compensate the capacitor current, meet the requirements of grounding fault safety current and suppress transient overvoltage when the grounding fault occurs;.3) Propose a large-scale generator stator ground fault location method that takes the optimal design of the stator winding into account. According to the analysis of the constituent characteristics of the wave winding generator branch electromotive force, the location result is precise to within a winding bar..The project achievement will ensure the safety of the stator core of large generators in the event of a stator grounding fault, and avoid returning the stator core to the factory for repair or reassembling on-site. Besides, it can accurately locate the winding bar where the fault occurs, shorten the time for fault maintenance. Overall, it has significant economic benefits and social benefits.