水轮发电机定子绕组内部短路故障的电磁问题研究

发布时间：2018-07-01 17:40

本文选题：水轮发电机 + 内部故障　；参考：《哈尔滨理工大学》2014年硕士论文

【摘要】：水轮发电机定子绕组内部故障破坏力极强，会对发电机本身甚至电力系统的稳定运行造成严重影响。因此水轮发电机组必须配置有效的主保护方案，以便及时检测出机组的内部故障。通常要求发电机的主保护在故障后1个周波左右动作，此时电机的过渡过程还没有结束，因此需要准确地计算水轮发电机定子绕组内部故障暂态过程。本文基于场路耦合法以矢量磁位和回路电流为求解变量，建立了分析同步发电机绕组短路故障的数学模型，，该模型兼顾了多回路分析法和电磁场有限元法的共有优点，使分析结果更接近实际情况。本文以SF600－42/1308水轮发电机为研究对象，建立了SF600－42/1308水轮发电机—变压器—无穷大电网的场路耦合模型。首先，仿真计算了该电机空载状态下定子绕组突然三相短路的暂态过程，并将本文的仿真结果与经典的解析公式法进行了对比，验证了本文分析方法及模型的正确性。其次，依然保持发电机为空载状态，仿真计算了定子绕组发生匝间短路、同相异分支短路和相间短路故障的故障分支电流、短接线电流、励磁电流和非故障分支电流的瞬态波形。分析了各电流波形的谐波含量，揭示了内部故障后各分支电流的特点。并将相应电流的基波幅值与多回路法的分析结果进行了对比，验证了本文提出的数学模型分析发电机内部故障的准确性。并且，本文还分析了以上3种内部故障的故障分支电流随短路匝比（差）的变化规律，以及故障发生的位置和时刻对故障分支电流的影响。最后，以匝间短路为例，在额定负载工况下仿真计算了故障后阻尼绕组中的涡流波形。分析了涡流产生的原因，揭示涡流波形的特点。并研究了阻尼绕组节距、阻尼条直径和阻尼绕组约束方式对内部故障电流量的影响，为进一步研究内部故障后阻尼绕组中的涡流提供参考。
[Abstract]:The internal failure of hydrogenerator stator windings is extremely destructive, which will seriously affect the stable operation of the generator itself and even the power system. Therefore, the turbine generator must be equipped with an effective main protection scheme in order to detect the internal faults of the unit in time. The main protection of the generator is usually required to operate at about 1 Zhou Bo after the fault, and the transient process of the motor is not over, so it is necessary to accurately calculate the transient process of the fault in the stator winding of the hydrogenerator. Based on the field circuit coupling method, a mathematical model for the analysis of short circuit faults of synchronous generator windings is established using vector magnetic potential and loop current as the solution variables. The model takes into account the common advantages of the multi-loop analysis method and the electromagnetic field finite element method. The results of the analysis are closer to the actual situation. In this paper, the SF600-42 / 1308 hydrogenerator is taken as the research object, and the field-circuit coupling model of SF600-42 / 1308 hydrogenerator, transformer and infinite power network is established. Firstly, the transient process of the stator winding with three phase short circuit in the no-load state is simulated, and the simulation results are compared with the classical analytical formula method, which verifies the correctness of the analysis method and the model. Secondly, the generator is still in the no-load state. The fault branch current and short connection current of stator winding with inter-turn short circuit, same phase and different branch short circuit and interphase short circuit fault are simulated and calculated. Transient waveform of excitation current and non-fault branch current. The harmonic content of each current waveform is analyzed, and the characteristics of each branch current after internal fault are revealed. The comparison of the fundamental amplitude of the corresponding current with the analysis results of the multi-loop method verifies the accuracy of the mathematical model proposed in this paper for the analysis of the internal faults of the generator. In addition, the variation of fault branch current with short-circuit turn ratio (difference) and the influence of fault location and time on fault branch current are also analyzed in this paper. Finally, taking inter-turn short circuit as an example, the eddy current waveform in damping winding after failure is simulated under rated load condition. The causes of eddy current are analyzed, and the characteristics of eddy current waveform are revealed. The effects of pitch distance of damping winding, diameter of damping strip and restraint mode of damping winding on internal fault current are studied, which provides a reference for further study of eddy current in damping winding after internal fault.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM312

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