蒸发冷却大电机定子主绝缘的试验研究

针对大型蒸发冷却电机的定子设计出一种新的绝缘结构 ,由冷却介质承担主绝缘使主绝缘厚度大幅减薄。用13.8k V电压等级的定子模拟线棒试验的结果表明 ,这种新型主绝缘可行。     

135MW全浸式蒸发冷却电机定子的绝缘结构

为了将拥有我国自主知识产权的蒸发冷却技术应用于高电压、大容量的汽轮发电机,并作为主力机组,需要解决定子绝缘结构的合理设计问题。全浸式蒸发冷却定子需要利用蒸发冷却介质的绝缘性能,大幅度减薄定子主绝缘的厚度,实现冷却与绝缘的双重功效。为此运用有限元数值仿真理论,首先详细计算并分析了该冷却方式下的定子绝缘结构内的电场与温度场,总结其分布规律与特点,证明了135MW全浸式蒸发冷却汽轮发电机主绝缘减薄的的合理性与可能性。这些仿真计算的结果通过了试验模型的检验,是合理可靠的,在此基础上提出定子主绝缘厚度的合理设计值以及对应的电流密度。研究结果值得国内制造业的借鉴。     

绝缘文摘与专利

脉冲电压对电机定子绝缘影响的试验研究,电器附件产品中绝缘材料部件的安全性要求及检测方法,135MW全浸式蒸发冷却电机定子的绝缘结构     

135MW蒸发冷却汽轮发电机定子绝缘结构的研究

为了将蒸发冷却技术应用于高电压、大容量的汽轮发电机,并作为主力机组,需要解决定子绝缘结构的合理设计问题.本论文针对蒸发冷却的特点,提出采用浸润式蒸发冷却定子的间接冷却方式,详细计算并分析了该冷却方式下的定子绝缘结构内的电场与温度场,总结其分布规律与特点.在此基础上提出135MW蒸发冷却汽轮发电机定子的绝缘厚度以及相应的电流密度,并通过了试验模型的检验,研究结果值得借鉴.     

蒸发冷却对高压电机电场分布改善的研究

为尽早开发国内24 kV级大型汽轮发电机,提出了采用蒸发冷却方式的技术路线。根据蒸发冷却介质高绝缘性能提出了一种适于该冷却方式的高电压等级汽轮发电机新型定子绝缘结构。采用有限元数值计算软件仿真了电机定子槽内与端部高压静电场的分布状况,列出了若干组电场强度的计算结果,据此详尽地分析了蒸发冷却方式下形成的气、液、固三态绝缘系统的耐电晕、耐击穿的可靠性,系统地研究了新定子绝缘结构的特点及规律。结果表明该新型绝缘系统无需防晕处理,可实现主绝缘仅4 mm的24 kV等级蒸发冷却汽轮发电机。     

蒸发冷却技术应用于大型汽轮发电机的技术可行性

针对大型汽轮发电机的发展要求,介绍了汽轮发电机定子蒸发冷却及转子蒸发冷却的原理和结构.详尽地分析了蒸发冷却技术应用于大型汽轮发电机的可行性,得出定子浸润式、转子开放管道式蒸发冷却方案应用于大型汽轮发电机在技术上是可行的结论;同时对汽轮发电机转子绕组开放管道式蒸发冷却技术进行了模拟实验,实验目的是为了取得开放管道式转子绕组沿半径方向的温度分布情况,并粗略估计冷却能力,旨在为蒸发冷却汽轮发电机向更大容量发展、探索新的冷却结构提供技术参考.     

330MW蒸发冷却汽轮发电机转子穿装工艺

蒸发冷却技术是我国自主研发的新型冷却技术,由于发电机定子采用全浸泡式蒸发冷却,其结构同常规发电机有很大的不同,其装配工艺也不同。文章主要介绍了330MW蒸发冷却汽轮发电机厂内总装时转子穿装的工艺方案的制定和实施。     

发电机定子线棒的电磁振动和磨损

两年来,许多发电厂的TQN型汽轮发电机相继发生定子主绝缘大面积磨损问题,威胁着安全运行。造成发电机主绝缘大面积磨损的主要原因,是载流定子线棒的电磁振动。对于10万千瓦级的汽轮发电机,人们往往因其槽电流不很大,而忽视了结构改进和工艺质量。对于更大容量的发电机,能否有效地限制电磁振动,承受长期满发和可能的系统故障,问题将更加突出。这是因为发电机单机容量的增大,主要是通过冷却方式的发展和冷却结构的改进,来增大发电机的功率密度,而定子电压不能提得很     

高速永磁电机的转子涡流损耗分析

在高速永磁电机中,转子涡流损耗会使转子温度升高,影响电机效率等性能,甚至导致永磁体过热退磁.针对高速永磁电机中的转子涡流损耗问题,进行了解析分析和有限元计算,分析了产生转子涡流损耗的谐波来源,研究了不同定转子结构电机的转子涡流损耗,分析了定子槽数、槽口宽度、气隙长度、屏蔽层、定子齿开辅助槽对转子涡流损耗的影响.结果表明,增加定子槽数、减小槽口宽度、增加气隙长度可以减小转子涡流损耗;在护套和永磁体中间加一层高电导率屏蔽层能有效减小永磁体的涡流,且选择合适的屏蔽层厚度能够进一步减小转子涡流损耗;提出了使用合适宽度、深度、角度和槽型的辅助槽来减小转子涡流损耗、帮助电机散热的新方法.对高速永磁电机的研制具有重要的理论研究和工程应用价值.     

隐极同步电动机冷却空气流场特性研究

为了研究在相应通风道结构下某变频调速隐极同步电动机冷却空气流场的特点,建立了包括定子和转子风道的电机1/8结构的三维流场物理模型,基于有限体积法,对三维湍流流动控制方程进行数值求解,得到了两种额定转速时电机内各部分空气流速、空气流量分布的特点。结果表明,在计算条件下,转子转速分别为3120r/min、4800r/min时,定子部分流过定子端部、压指间、定子铁心段径向通风沟及转子部分的冷却空气流量分配百分比基本不变,转子端部未布置补风口的3号槽与布置补风口的6号槽冷却风量较小。所得结论可为通风道结构设计提供参考。     

探讨大型变频调速矿井提升同步电动机设计的特殊性

针对大型矿井提升同步电动机和为其供电的交-交变频电源的特点,概括介绍了此类电机的电磁、结构等方面的设计要点。在电机电磁设计方面,说明了对于使用变频电源下,如何选择电机容量、额定电压,确定极对数、定子铁心外径及气隙磁密、定子线圈每相串联匝数和定子铁心长度等初步设计需要考虑的问题。进而对详细计算进行说明。在结构设计方面,分别对定转子的组成和定转子线圈结构特点进行了简要介绍。所生产的电机不仅在性能上满足用户的要求,而且经济指标也在逐步提升。     

An aid for teaching doubly fed synchronous machines based on thecircle diagram

This paper discusses with the extension of the circle diagram to the doubly fed synchronous machine (DFSM). Beyond the slip, this graphical approach is characterized by two leading parameters: the rotor voltage root-mean-square value and the angle between the stator voltage phasor and the rotor voltage phasor referred to as the stator windings. The generalization of the torque line in the case of the DFSM has allowed the machine power flow analysis     

大型汽轮发电机故障特征规律的研究

介绍了大型汽轮发电机现场故障特征规律分析研究的结果,给出了大型汽轮发电机的静子断水,静子漏水,转子漏水、静子线圈过热,静子绝缘损坏,静子接地,转子一点接地、转子绕组匝间短路、转子不平衡、轴承油膜振荡、轴瓦损坏、机座外壳振动等１２种常见故障的模式与后果,特征信号,特兆和诊断规则,以及基于可靠性理论的发电机常见故障发生概率的计算公式。文中使用的电气信号,振动信号以及水或氢冷却子系统和润滑子系统的液压等     

交流差频电力测功机的方案研究

本文论述的“交流差频电力测功机”方案是一种节能型电力功机。测功电机定子直接接电网,转子与内燃机同轴连接,差频发生器给转子绕组提供一个电压和频率可调,相序可变的三相交流电源,达到回收内燃机试验能量的目的。     

Nonlinear model and momentary performance capability of a cagerotor induction machine used as an automotive combinedstarter-alternator

This paper presents the calculated and the measured performance capability of a cage rotor induction machine used as a direct connected, crankshaft speed, combined starter-alternator for an automotive diesel engine in an experimental hybrid electric vehicle. The calculated results are based on a nonlinear equivalent circuit model of the machine in which saturation is considered only in the stator and rotor magnetizing flux paths. The development details of this model are given as well as several sets of calculation results for a prototype induction machine. Finally, measured maximum performance results for the test machine are presented and compared with model-based calculated results for the same operating conditions of speed, terminal voltage and current     

电机电磁计算中的各种磁导率

本文讨论电机中铁磁材料的各种不同的磁导率,介绍了典型的凸极同步电机转子材料增量磁导率的测量结果,并给出了电机定,转子铁心典型材料的各种磁导率,文章最后还给出了应用不同磁导率计算变频器供民的同步电机运算电感的实例。     

Lower speed range drive for sensorless vector controlled induction machines with stator voltage offset compensation method

The vector control method is widely used for induction machine drives. Recently, sensorless vector control for induction machines has been investigated and proposed. The speed range for the drives is limited to about 1:100 in industry. The main reason for this limitation is the inaccuracy of stator voltage measurement. The lower the rotor speed is, the lower the stator voltage. Therefore, it is difficult to detect the stator voltage accurately in the lower speed region, and difficult to control motor speed and motor torque precisely. This paper presents a method of improving the lower speed performance of sensorless vector controlled induction machine drives using offset compensation of stator voltage. The offset is compensated by using the fluctuation of the estimated rotor flux. The validity of the proposed method is verified by experimentation. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 79–86, 2000     

Memory motors

A new class of permanent-magnet (PM) machines, named memory motors for their ability to change the intensity of magnetization and memorize the flux density level in rotor magnets is described in the article. A memory motor can be built either as a variable-flux or pole-changing machine. In both machine types, the magnetization of PMs can be simply varied by a short current pulse, with no need for permanent demagnetizing current as in conventional internal PM machines at flux-weakening mode. The demagnetizing current flows through stator winding(s) supplied from the same source as the stator current. Memory motors combine advantages of a wound-rotor machine (variable rotor flux) with those of a wide-speed machine (no excitation losses), resulting in a unique machine concept that has the potential to find numerous applications in electric drives.     

Robust control of doubly fed induction generator for stand-alone applications

The doubly fed induction generator (DFIG) is generally used in the production of the electric energy and more specifically in wind turbines. Currently, a problem of electrical machine control and especially for wind turbines is the change of internal parameters of the machine, which greatly deteriorates the control. In addition, for stand-alone applications, the load and wind speed change frequently. In this paper, a robust control strategy based on the H_∞ control theory is developed for the independent control of the stator voltage amplitude and frequency of a stand-alone DFIG. The DFIG is fed through the rotor windings by a voltage inverter controlled by Space Vector Modulation (SVM). A capacitive and inductive filter is introduced to reduce harmonics on stator voltages and rotor currents. The robust control strategy rejects all the disturbances that may affect the system and that result from the variations of machine parameters, of the rotor speed and of the load. Experimental tests are carried out to verify the effectiveness of the robust control through a comparison with the classical PI regulator in the framework of the Field Oriented Control (FOC) strategy of the DFIG.