【作者】 侯纪勇；

【导师】 李和明； 李俊卿； 王红宇；

【作者基本信息】 华北电力大学（北京） ， 电气工程， 2011， 博士

【摘要】 发电机励磁绕组匝间短路是常见故障,准确检测和及时诊断是保障机组安全运行的有效措施。本文对汽轮发电机励磁绕组匝间短路时励磁磁动势分析、数学模型建立、仿真分析及励磁绕组匝间短路诊断判据和定位方法进行了深入探讨和实验研究。完成的主要工作和取得的成果如下：1.对汽轮发电机励磁绕组短路时励磁磁动势进行了分析,得到了其级数表达式,可对汽轮发电机励磁绕组正常和不同匝数、不同线圈匝间短路时励磁磁动势定性和定量分析,解决了不同励磁线圈短路时励磁磁动势难用分段函数表示的间题,且可考虑励磁磁动势各次谐波的单独作用。得到了汽轮发电机励磁绕组正常和不同匝数、不同线圈短路时励磁磁动势分布图、励磁磁动势基波和各次谐波幅值的变化规律,与实验时空载分支电压频谱分析结果一致。2.对励磁绕组不同匝数和不同线圈的匝间短路,完成了考虑饱和和齿槽效应影响的有限元计算分析,总结了短路不同匝数、短路不同线圈与气隙磁通密度变化规律的对应关系。其结果与励磁磁动势的分析结果相互吻合。3.建立了汽轮发电机空载和并网时励磁绕组匝间短路的多回路数学模型。该模型将短路的励磁绕组等效为故障回路和正常回路,用磁导分析法推导了与励磁绕组有关的电感系数计算公式,给出了数学模型中各回路参数的计算方法。该模型适用于发电机绕组正常和励磁绕组匝间短路仿真。4.采用多回路数学模型完成了汽轮发电机励磁绕组不同匝数、不同线圈短路仿真和故障特征量分析,并进行了实验研究。得到了励磁绕组不同匝数、不同线圈短路时相电压、励磁电流、定子并联支路环流的变化波形及其各次谐波的变化特征,仿真与实验波形吻合,表明了数学模型的正确性。完成了300MW汽轮发电机励磁绕组匝间短路仿真,表明了数学模型的实用性。5.通过理论分析,提出了基于定子分支电压和并联支路环流偶数次谐波2-范数的励磁绕组匝间短路诊断判据。通过研究不同线圈、不同匝数短路时定子并联支路环流偶数次谐波幅值2-范数和相电压3次谐波幅值的比值变化规律,揭示了该比值与短路励磁线圈号的一一对应规律,给出了实现励磁线圈匝间短路故障定位方法。并对动模实验室7.5kW汽轮发电机进行了转子改造设计和安装调试,完成了励磁绕组实验研究。理论分析、数值仿真和实验结果吻合,验证了上述诊断判据和定位方法的可行性。更多还原

【Abstract】 Field winding inter-turn short circuits is a common fault of the generator, accurate detection and timely diagnosis are effective measures to guarantee the safe operation of generators.The field magnetic motive force (MMF) analysis, mathematical model, simulation analysis and the diagnosis criterion and localization method of field winding inter-turn short circuits in turbine generator are deeply discussed and experimental studied in this dissertation. The major work done and results achieved are as follows:1. The field MMF of the turbine generator with field winding short circuits was analyzed, and a series expression was obtained, which is suitable for the qualitative and quantitative analysis of the turbine generator’s field MMF with normal winding and field winding different turn number and different coils short circuits. The series expression not only solves the problem that is difficult represent the field MMF in piecewise function with filed different winding coils short circuits but also considers field MMF harmonic’s independent effect. The field MMF distribution and the amplitude variation of the fundamental and harmonic in turbine generator with normal field winding and field winding different turn number and different coils short circuits were obtained, which are identical to the spectrum analysis results of the tested no-load phase voltage.2. The finite element analysis of the field winding different turn number and different coils short circuits considering the saturation and slot effect was completed. The correspondence between the short circuit turn number and flux distribution and the correspondence between the short circuit coil and flux distribution were summarized. Conclusion is consistent with theoretical analysis.3. The multi-loop mathematical model of the turbine generator with field winding inter-turn short circuits under no-load and grid was established. The short circuit field winding of the model is equivalent as the fault loop and the normal loop, the field winding’s related inductances were deduced in permeability analysis method, the loop parameter’s calculation method was gived, the model is suitable for the simulation of generator with normal winding and field winding inter-turn short circuits.4. Simulation analysis and experimental research of the turbine generator with field winding different turn number and different coils short circuits were achieved. The simulation and experimental waveform comparison shows the validity of mathematical model. The harmonic variation of the phase voltage and field current and the stator’s parallel branch circumfluence after field winding different turn number and different coils short circuits were obtained. Simulation of the 300MW turbo-generator with field winding inter-turn short circuits was completed, which shows practicality of mathematical model. 5. The diagnosis criterions that are 2-norm of the branch voltage and parallel branch circumfluence’s even harmonics maximum quantity were presented by theory analysis.The change feature of the ratio of the parallel branch circumfluence even harmonics maximum quantity’s 2 norm and the phase voltage 3rd harmonic maximum quantity was studied,the one-to-one correspondence between the ratio and field coil was found,The field winding inter-turn short circuits fault localization method was given.The rotor design transformation, installation and commissioning of the 7.5KW turbine generator in dynamic simulation laboratory were completed. The field winding different turn number inter-turn short circuits experiment was carried out.Theoretical analysis, simulation and experimental results are in agreement.更多还原