大型水轮发电机进相运行分析

本文对大型水轮发电机进相运行了计算和分析，除了考虑静稳极限和定子端部温升对进相运行的限制外，还计及了定子电流限制和低励限制的影响。并针对某厂２００ＭＷ水轮发电机投入运进后对所在电网的影响，进行了计算和分析，提出Ｐ－Ｑ运行图和该机组进相运行时的意见，对运行人员有实用参考价值。     

某电厂2号发电机组深度进相运行能力综述

发电机由迟相运行转为进相运行,就是说从发出无功功率转为吸收无功功率时,励磁电流愈小,可从系统吸收的无功功率越多,功率角也越大,故发电机允许吸收多少无功功率,发出多少有功功率．决定于静稳定的极限角。此外发电机定子端部漏磁和转子端部漏磁的合成磁通增大会引起发电机定子端部发热,这些都是我们在这里要探讨的主要问题。     

浅谈发电机励磁系统

近年来,新技术、新工艺、新器件不断的涌现出来,并不断的投入使用,完善和发展了发电机的励磁方式,并推广使用许多新型的调节装置。励磁系统的主要作用表现在根据发电机负荷的变化相应的调节励磁电流来维持机端电压为给定值,控制并列运用各发电机问无功功率分配,提高发电机并列运行的静态稳定性,提高发电机并列运行的暂态稳定性,在发电机内部出现故障时进行灭磁减少故障损失程度,根据运行要求时发电机实行最大励磁限制及最小励磁限制。本文还谈论了发电机励磁系统的一些方式和形式。     

发电机进相运行稳定性分析

结合发电机进相运行的数据,分析发电机进相运行时对定子绕组温度、厂用电压、发电机静态稳定性的影响,论证发电机进相运行时的稳定性。     

大型空冷汽轮发电机绝缘结构研究

大型空冷汽轮发电机定子线棒主绝缘性能与多种因素有关,包括绝缘体系、绝缘材料、绝缘结构、制造工艺、角部电场处理等,本文从线棒的主绝缘体系、线棒角部电场强度分布改善、绝缘材料选择、线棒端部防晕处理、绝缘制造工艺改进等多方面阐述了大型空冷汽轮发电机定子线棒绝缘结构研究。     

大型汽轮发电机定子绕组端部模态仿真与试验研究

大型汽轮发电机运行时会受到端部电磁力的作用,当电磁力的频率或者二倍工频与定子绕组端部的固有频率接近时,容易发生较大的振动,产生安全隐患,故需要对定子绕组端部振动情况进行研究。本文建立了定子端部准确的三维模型;为方便计算,对有限元模型进行了简化,进行了模态分析,获得了前两阶的振型;采用试验法进行模态测试,并将仿真计算结果与试验结果进行对比,并进行了误差分析,二者误差在合理范围内,从而验证了本文仿真的合理性,为汽轮发电机的设计和安全运行提供依据。     

大型汽轮发电机定子绕组端部振动管窥

本文通过对大型汽轮发电机定子绕组端部振动原因分析,并进一步阐述了相应的改进策略,旨在为减少大型汽轮发电机定子绕组端部振动起到借鉴作用。     

气隙轴向静偏心对发电机定子-绕组受载及振动的影响

通过理论推导、有限元计算和实验验证,研究了气隙轴向静偏心前后同步发电机定子及绕组的受载与振动特性变化。与其他大部分气隙径向偏心的研究不同,本文重点关注气隙轴向静偏心下定子-绕组的受载及振动特性。在分析气隙磁密变化的基础上,推导得到了正常和气隙轴向静偏心下定子径向及轴向不平衡磁拉力、绕组电磁力的表达式。以CS-5型发电机为分析对象,进行了有限元仿真计算和实验验证。结果表明,气隙轴向静偏心会在减小定子径向磁拉力和转子抽空端定子绕组电磁力的同时增加定子轴向不平衡磁拉力和转子伸出端定子绕组电磁力,对应地,定子径向振动和转子抽空端定子绕组振动将减小,但定子轴向振动和转子伸出端定子绕组振动将增大;定子轴、径向磁拉力和绕组电磁力及振动均以二倍频为主,夹杂其他各偶次倍频。在定子磁拉力作用下,定子铁芯齿槽端部为最大变形位置;在定子齿槽变形挤压和电磁力共同作用下绕组直线段与端部的连接处易发生磨损,在制造及运行中需给予特别注意。     

汽轮发电机定子绕组端部振动模态分析

结构振动问题在大型汽轮发电机中普遍存在,尤其定子端部绕组的振动问题最为突出。定子绕组端部的振动模态分析是减小端部振动的有效手段。利用三维有限元法模态分析,通过比较、分析发电机定子绕组端部振动系统的固有频率在不同模型结构和绕组安装工艺条件下的变化,总结出线棒的截面结构和加固结构对电机固有频率的影响规律。通过比较完整系统的模态分析计算结果和实测结果,证实了模态分析计算的有效性。分析结果对定子绕组端部结构设计和安装工艺有很大指导意义。     

新疆伊犁特克斯河山口水电站1号机组进相试验

2011年7月,新疆伊犁特克斯河山口水电站对1号发电机开展进相试验。通过试验,系统而全面地验证一、二次设备对机组的适应性及进相能力,并对机组实际电网进相运行注意问题和限制条件有进一步认识,为电网利用水电机组调节无功控制电压提供依据。     

发电机出口PT匝间短路故障分析

某电厂发变组保护A、B柜分别报"定子零序电压高段保护动作",引起机组跳闸。检查该发电机发变组保护动作、故障录波器均正常,现场发现发电机出口电压互感器（potential transformer,PT）B相5042PT有明显过热。通过分析事故经过,对故障PT完成直阻、绝缘、励磁特性曲线、空载电流测试等试验,确认发电机PT匝间短路是造成此次机组跳闸的主要原因。针对如何提前发现发电机出口PT绝缘裂化故障提出了相应的防范措施,应严格按预试规范要求完成发电机出口PT的局放、3倍频耐压等试验,并对各项常规预试项目数据进行趋势分析,及时发现异常。通过此次发电机出口PT匝间短路故障分析对及时发现设备安全隐患,提高设备运行可靠性起到较好排查作用。定期按规范要求完成相关试验,重视试验数据的趋势分析能有效降低同类型事故发生概率及减小事故范围。     

Semi-analytical method for determining d-axis synchronous generator parameters using the dc step voltage test

The DC step voltage experiment is an alternative and non-destructive time-domain test to extract parameters from electrical machines that follows the standstill frequency response test procedure described in IEEE standard 115A. This work presents a new method for semi-analytically determining the characteristic parameters of the d-axis synchronous machine model. The test is carried out when the machine is at rest and the rotor's position is at d-axis; a DC-controlled power source is applied suddenly at two of the three terminals of the stator machine and the field circuit is short-circuited. Test measurements of d-axis stator voltage excitation and field and d-axis stator current responses were used. Both stator and field current patterns are simultaneously fitted to exponential functions which coefficients are analytically related to the d-axis characteristic parameters of the equivalent circuit. These characteristic parameters come from the conventional two transfer functions: direct-axis operational inductance L_d(s) and the armature to field transfer function sG(s). To validate the proposed methodology, test data is used in the d-axis parameter determination of a 7 kVA, 220 V, 60 Hz synchronous generator     

R.F. diode sputtering in permanent-match mode

A constans-voltage r.f. diode sputtering set incorporating a self-excited oscillator was designed. The variable discharge impedance was stabilized, as seen from the r.f. generator output, by suitable capacitive discharge shunting combined with a rather tight coupling to the generator. A conventional r.f. power oscillator of the Colpitt type was used and, as the loading of the oscillator by the discharge and its associated electrical network was essentially constant, there was no need for an impedance matching network or voltage-and/or power-controlling servosystems to assure stable operation of the equipment.For bias sputtering, the variation in the substrate holder voltage was established by variation of the mutual inductance to the bias circuit which allows the bias voltage to be operated in phase or 180° out of phase with respect to the target voltage. The r.f. generator had a line-modulated power supply; its influence on the accelerating voltages governing sputtering was considered and the ion energy distribution was studied. The operation of the equipment is illustrated by refractive index results obtained in TiO₂ films deposited by in-phase and inverse-phase bias sputtering.     

Dynamic electromagnetic torque model and parameter estimation for a deep-bar induction machine

A dynamic analytical electromagnetic torque model for a deep-bar induction machine is presented. The model is based on the space-vector theory of electrical machines. The parameters are estimated using the data provided by the numerical impulse response test performed within the two-dimensional time-stepping finite element analysis. Two different impulse tests are studied. The impulse excitation is applied to the stator voltage and rotor position angle, and the parameter estimates are compared. The applicability of the impulse test is based on the assumption of linear behaviour in the neighbourhood of an operation point. Hence, one of the main objectives is to study the validity of the impulse test. From the results of the angle impulse test, a frequency range of negative damping is detected. The phenomenon is also studied by measurements.     

Synchronous generator third-order model parameter estimation using online experimental data

A method to estimate the dynamic parameters of the commonly used third-order d-q model of a synchronous generator, based on measured electrical power, reactive power, terminal voltage, field current, field voltage and rotor angle following a small perturbation of the field voltage, is described. The parameters are estimated from two newly developed nonlinear functions for electrical power and terminal voltage by using a nonlinear least squares (NLS) algorithm. Results of simulation studies and experimental data collected from an 80 MVA, 10.5 kV generator show the efficacy of the proposed method and also reveal that the proposed method is valid for a wide range of operating conditions. For cases where rotor angle is not available, a new method for rotor angle estimation is also proposed.     

3-D Electromagnetic Force Distribution in the End Region of Turbogenerator

The paper deals with detailed investigation of the electromagnetic forces in the end zone of turbine generator. The electromagnetic field is analyzed using 3-D FEM computation. The regions of interest are the stator and rotor end cores including the zone of the teeth and the end windings. The dynamic behavior of the local electromagnetic force densities is studied in accordance with the working mode. Two modes at the leading and at the lagging power factor are considered. Comparison between the ratio of the local electromechanical loads under considered modes and the relevant loads at the rated mode is discussed and appropriate conclusions are drawn. Calculations are implemented on a 200 MW turbine generator.      

复合式罩极电机扭转振动检测与分析

设计了一种复合式罩极电机,为双定子双转子结构,电机运行时定子绕组施加励磁,产生的旋转磁场带动转子旋转。分析了电机气隙磁场的特性,推导了电磁转矩公式,表明电机运行时存在扭转振动。研制了复合式罩极电机样机,利用传感器对电机在不同励磁状态下的转矩输出进行了检测,表明电机运行时存在扭转振动,且扭振幅值随两相励磁电压的相位差而变化,最后对变化规律进行了理论分析,结果表明:扭转振动波的相位差为两相励磁电压相位差的2倍。     

Voltage and frequency control of parallel operated synchronous generator and induction generator with STATCOM in micro hydro scheme

Parallel operation of synchronous and induction generators in micro hydro scheme is presented. The synchronous generator has an exciter, which provides a fixed excitation to produce normal rated terminal voltage at full resistive load. On the other hand, the induction generator has neither exciter nor speed controller. Static compensator (STATCOM) is connected to the common bus for terminal voltage and frequency control. A resistive dump load is connected across the DC link capacitor of STATCOM through a chopper to control active power. Simulink model is developed to perform transient analysis of the proposed scheme. Experimental results are presented to compare with the simulation results. It is found that connection of an induction generator in parallel with the synchronous is much simpler than connecting two synchronous generators in parallel.     

发电机定冷水系统不明异物的表征和分析

为解决发电机定子线圈槽的异常升温现象,利用扫描电子显微镜、能谱仪等现代分析手段对300MW发电机定冷水系统不明异物进行了表征和分析。结果表明,定冷水箱中的不明异物是离子交换有机树脂、腐蚀产物氧化铜、氧化铁以及外部引入的硅胶和泥沙;过滤网中的不明异物是腐蚀产物氧化铁及碳酸钙等所组成的颗粒混合物。由于异物的堵塞导致发电机定子线圈槽的异常升温。提出了解决方法,为大型发电机组长期安全稳定运行提供了实用数据和科学依据。     

间接激励压电发电机的建模仿真与试验研究

为满足旋转机械监测系统的自供电需求、解决现有压电发电机可靠性低及有效带宽窄等问题,提出一种基于移动凸轮间接激励并限幅的旋转式压电发电机(简称间接激励压电发电机).介绍了发电机的结构原理并进行了建模仿真与试验测试,获得了激励磁铁数量比、凸轮升程及升角对激振力形式/幅值、压电振子变形量/输出电压及发电机带宽等的影响规律.结...