【作者】 刘广；

【导师】 姚缨英； 吴金水；

【作者基本信息】 浙江大学 ， 电气工程， 2012， 硕士

【摘要】 为研究水轮发电机的不对称运行能力,准确反映水轮发电机各种不对称运行工况下的运行状态,本文对水轮发电机的稳态不对称运行工况以及因负载突然短路故障所造成的短时不对称运行工况下的电磁场和温度场进行了系统的分析,总结了各种运行工况下的电磁场和温度场分布规律。首先,针对水轮发电机不对称运行时的不同运行工况,分别建立了水轮发电机转子的二维时谐稳态电磁场计算模型和二维时变运动电磁场计算模型。并对其中的场路耦合问题、转子旋转问题及后处理中阻尼绕组电流与损耗确定等问题进行了深入的研究。其次,建立了水轮发电机转子磁极的稳态温度场和暂态温度场数学模型,对其中热源载荷的确定、散热系数确定、迎风面与背风面散热系数差异以及电磁场和温度场的耦合求解方法等问题进行了探讨。随后,采用有限元法对水轮发电机负序稳态运行时的电磁场和温度场进行稳态分析,得到了该工况下电磁场和温度场分布,总结了其分布规律,并对磁极表面附加损耗、阻尼绕组气隙建模、耦合场热源加载及负序电流比等因素对温度场的影响进行了研究。最后,采用有限元法对水轮发电机在额定运行基础上发生的负载突然单相接地短路、两相短路和三相短路故障工况时的电磁场和温度场进行了瞬态分析,得到了故障瞬态过程结束后的电磁场及温度场分布规律和转矩、定子电流及阻尼绕组电流及损耗在瞬态过程中的变化曲线,确定了各种负载突然短路故障对水轮发电机的危害程度及造成危害的主要原因。本文的研究对水轮发电机的合理设计和可靠运行,乃至整个电力系统的安全运行都具有十分重要的意义,具有非常高的工程价值和学术价值。更多还原

【Abstract】 The finite-element method had been taken in analysis of hydro-generator’s electromagnetic field and temperature field on asymmetric operating conditions.Firstly, the 2-D time-harmonic and time-stepped movement electromagnetic field models and the steady-state and transient temperature field models had been established. The field-circuit coupled, the rotating of the rotor, the difference between the windward side and the wind surface, and the coupled field solving method of electromagnetic field and temperature field had been discussed. The determining of the current and loss of damper windings, the loads and the thermal coefficient of temperature field had been studied.Secondly, steady-state finite-element analysis of the electromagnetic field and temperature field had been taken on the steady negative-sequence operating condition of hydro-generator. The accurate distribution of electromagnetic field and temperature field had been obtained. And the distribution law had been summarized. The impact on temperature field of the additional loss of pole surface, the modeling of the damper air-gap, the coupled field method to apply load had been studied.Thirdly, transient finite-element analysis of the electromagnetic field and temperature field had been taken on the rated operating condition and the sudden single-phase ground short-circuit fault, sudden two-phase short-circuit fault, sudden three-phase short-circuit fault that based on the rated operating condition. The distribution law of electromagnetic field and temperature field, and the curve of the torque, the stator current and the damper winding loss and current over time had been obtained. The harm degree of every sudden short-circuit fault had been determined.The study is very important to the design and the operation of hydro-generator. It is also very important to the safe operation of the whole power system. It has very high value to engineering and academic.更多还原