相复励旋硅式无刷同步励磁电机旋转二极管的故障监测

分析了相复励旋硅式无刷同步励磁电机旋转二极管的开路和短路状态,并以某大功率中速柴油发电机组为例,分析了其旋转二极管监测电路框图的工作原理,该监测电路在二极管开路时能延时发出信号,而在二极管短路时能迅速解列发电机,以维护机组的安全。最后对监测电路的实际性能进行了简要的说明和探讨。     

A discharge locating probe for rotating machines

The basic principles of an improved Tennessee Valley Authority (TVA) probe known as the discharge locating (DL) probe are presented. The principal features of the new device are very-high-frequency detection using a capacitive sensor and microprocessor-based signal processing. These features are intended to make the probe easier to use and less ambiguous in the interpretation of results. The coupling technique used permits significantly improved spatial resolution of the discharge source and immunity to radiated electrical interference. Details of the signal processing electronics and field experience are described     

PD pulse burst characteristics of transformer oils

Partial Discharge (PD) characteristics of four typical transformer oils, having respective viscosities of 3.5, 9.1, 13.0, 18.3 cSt at 40/spl deg/C, were examined under ac conditions, using a needle-to-plane electrode system. Wide and narrow bandwidth measurements were carried out to determine simultaneously the apparent charge transfers associated with the overall PD pulse bursts in the oil as well as that of the individual discrete PD pulses within the PD pulse bursts themselves. Based on the apparent charge transfer value, the size or depth of the PD initiating microcavities in the field direction within the oils, producing the first detected discrete PD pulse, were estimated to be in the order of 2 /spl mu/m. The recurrence rate of the PD pulse bursts was found to increase with voltage above the PD inception voltage; this increase was accompanied by both an increase in number of discrete PD pulses and their amplitude within the pulse burst itself. These increases were reflected by a substantial rise in the apparent charge transfer per PD pulse burst. The charge transfer levels of the PD pulse bursts associated with the highly pressurized gas microcavities were of the same order of magnitude as those produced within the normally much larger macroscopic cavities that exist under atmospheric pressure in conventional oil-impregnated insulating systems of power transformers.     

Importance of bandwidth in PD measurement in operating motors andgenerators

It is well known that partial discharge (PD) events produce electromagnetic radiation with frequencies from de to sometimes hundreds of megahertz. In addition, in complex structures such as stator windings, the initial pulses are significantly distorted and attenuated as they propagate through a winding. The detection of the PD pulses needs to account for these effects. In particular, the bandwidth of the detection system will influence the sensitivity of the PD measurement, as well as in what portions of the winding PD can be detected. This paper summarizes over 20 years of research into these effects in stator windings, and discusses the implications for off-line and on-line PD testing, and the calibration of the PD quantities into apparent charge     

Trends in insulation materials and processes for rotating machines

Market pressure for cost reduction and more rapid innovation has taken away the privilege for the insulation design engineers to re-test everything according to time-honored “in-house” methods     

PD pulse sequence analysis and its relevance for on-site PD defect identification and evaluation

Digital partial discharge (PD) diagnosis has become a state of the art, but computer aided procedures based on pattern recognition principles are negatively effected by on-site disturbances. The benefits and limits of expert diagnosis compared to machine intelligent systems are discussed. It is pointed out that a sufficient noise resistivity and test voltage independency of the diagnosis concept is a must for a successful on-site PD defect identification and evaluation. Experimental results are presented, taken into account especially novel evaluation procedures, which are more independent from the applied PD sensors. It is shown that PD defect identification on site at operating voltages and respectively disturbed data is still a challenge. A method of resolution with an intelligent noise resistant diagnosis concept is discussed. A hierarchical and redundant approach is presented, which improves the on site PD source identification as well as on-site risk assessment.     

Computer aided instruction of rotating electric machines viaanimated graphics

A menu-driven interactive graphics software package has been developed for use as an instructional aid for the electric machines course in the electrical engineering curriculum. The main purpose of this tool is to give the students a clearer understanding of the basics of the operation of rotating electric machines. The animation program was developed for displaying live and rotating diagrams depicting different modes of operation of synchronous generators. Different parts are identified with different colors. The interaction of the magnetic poles on the stator and on the rotor, and the relative spatial positions and time variations of the magnetic and electric quantities are demonstrated through moving images. The software features are described     

PD source recognition by Weibull processing of pulse heightdistributions

The problem of identification of partial discharge (PD) phenomena occurring in an insulation system is addressed in this paper. PD distributions coming from different sources, such as internal voids, as well as surface and corona discharges, are compared. In particular, the investigation focuses on the Weibull probability function applied to pulse charge-height distribution. It is shown that the different discharge sources can be identified on the basis of the value of the shape parameter of the Weibull distribution and that identification holds even when two PD sources are combined, i.e. are active simultaneously. In this case, the application of the 5-parameter Weibull function permits separation of PD phenomena, and recognition by means of the shape parameter value associated to each phenomenon. Finally, the proposed procedure is applied to practical objects, i.e. insulation systems of rotating machines, with real insulation defects, showing promising on-field application prospective     

单个局部放电脉冲测量系统

基于高频局部放电信号研究的需要,研制了一套用于提取单个局部放电脉冲的,具有较宽频率响应范围的测量系统,并利用校正脉冲对系统中的信号传输单元进行了校验,表明该系统可以满足测量要求,为确保提取到的放电信号真实可靠,对测量中存在的典型干扰信号的特征进行了研究,最后利用该系统测取了标准电晕放电的脉冲,与国际上同类测量系统所得结果基本吻合。     

Discrimination between PD pulse shapes using different neuralnetwork paradigms

A comparison has been carried out on the partial discharge (PD) pulse shape recognition capabilities of neural networks, using the nearest neighbor classifier, learning vector quantization and multilayer perceptron paradigms. The PD pattern recognition capabilities were assessed on artificial cylindrical cavities of different sizes. The performance of the three neural network paradigms was found to be equivalent in all respects, with the exception of the case where a distinction was required between small cavity sizes; under those circumstances, the learning vector quantization paradigm was distinctly superior to the two other paradigms. The experimental results also demonstrated that, even with simple metallic electrode cavities, the discrimination capabilities of the three types of neural networks are not always perfect     

基于插值法的旋转设备振动信号的谐波分析

为了实现对转频变化的振动信号的分析 ,提出了软件整周期采样。其核心是利用数学中的插值法 ,在不改变硬件采样频率的条件下 ,通过软件实现了对原信号的重新采样     

New practices for partial discharge detection and localization in large rotating machines

This paper presents a new technique for detection and localization of partial discharges (PD) in large rotating machines. In this technique, denoted "InTech", a stator winding with (n) coils is equipped with (n + 1) inductive sensors; as a result, every stator coil is situated between two sensors. The measurement is then focused on the individual stator coils. In this way common difficulties facing partial discharge measurements in rotating machines such as attenuation and distortion of the signals in the stator winding, noise reduction, and the calibration accuracy are reduced considerably. The treatment of the sensor signals, using a special method, results in a measurement of PD in each respective stator coil. In addition, the stator coil from which the PD originates is identified. Results from field measurements on both hydro and turbo machines are presented and discussed.     

Dielectric response studies on insulating system of high voltage rotating machines

A significant method to characterize the electrical properties of materials and to evaluate the condition of the insulating systems is the dielectric response study which can be done in the time or frequency domain. The dielectric response measuring results can be affected by different parameters like measuring voltage, temperature, water content and aging condition of insulating system. In this work numerous measurements are presented, thus to understand, how the dielectric response measurement results at the insulating system of high voltage rotating machines can be affected by these parameters in the time and frequency domain. Because of the importance of the dielectric response application as a non-destructive diagnostic method the possibilities and limitations of this method to reflect the deterioration processes due to thermal and electrical stress were also investigated. In addition the possibility to transfer the measuring data from the time to frequency domain was investigated and the calculated and measured data were compared. For the test object actual stator bars were used that were manufactured with epoxy VPI technology.     

Influence of supply voltage frequency and magnitude on PD pulse parameters

A study on the influence of supply voltage magnitude and frequency on partial discharge (PD) pulse shapes is presented in this paper. Ultrawide band (UWB) timeresolved PD pulse measurements were carried out on artificial PD defects using test voltage frequency range of 10 ? 400 Hz and voltage range of 2 - 11 kV. The manner in which the PD pulse shape responded to changes in the test voltage characteristics depended on the defect type. The observations can be interpreted using the generally agreed theory of PD mechanisms. The knowledge generated in this work is valuable in the interpretation and comparison of PD measurements made at different voltages and frequencies. It also contributes to development of PD defect classification techniques based on the correlation between test voltage frequency and time-resolved PD.     

A method for wide frequency range modeling of power transformersand rotating machines

Wide frequency range representation of power system components such as power transformers, reactors and rotating machines is mainly needed for the analysis of electromagnetic transients in power systems. In this paper, a method is presented for state space formulation of machine windings. The described procedure is completely based on external terminal impedance measurements and data related to the internal structure is not required. First, the wide frequency behavior of machine windings is reviewed and the nonlinearity effects of the iron core are discussed. A numerical method is given for calculation of the state equation parameters directly from the measured terminal impedance characteristics. The presented modeling method is applicable to any transformer, reactor or rotating machine in service where sufficient information on the internal design is not available. Besides, the canonical structure of the model offers advantages in terms of computer memory and computation effort in time domain analyses of complex power systems     

New electric insulating materials for the insulation systems of rotating electrical machines

A wide range of nomenclature and properties for new materials for the insulation of high voltage electrical machines and traction motors of F and H insulation classes developed at Elinar Holding Company are presented in the report.     

Modern electric insulating materials for the insulation systems of rotating electric machines

Modern insulation systems of turbo- and hydrogenerators, large electric machines, and traction motors based on new electric insulating materials (EIMs) produced by the JSC Elinar Holding Company (Elinar HC) are described briefly. The technical characteristics of some new EIMs are given.     

Experience with development and evaluation of corona-suppression systems for HV rotating machines

This paper presents the results of a project aimed at the development of reliable corona-suppression systems for high voltage rotating machines. These systems are based on both conducting and semi-conducting dry and B-stage tapes as well as paints of different resistivity. Three groups of anti-corona systems were developed; namely, paint (on the slot portion) - paint (on the slot exit) system, paint (on the slot portion) - tape (on the slot exit) system, and tape (on the slot portion) - tape (on the slot exit) system. Sample results of standard evaluation and acceptance tests are presented. The accelerated life-aging test was run on test coil samples at the National Electric Coil HV testing facility. A numerical 2-dimensional finite difference model for the electric potential and field analysis along the end-turn zone was developed and the model results are used as guidelines through the design process of the grading system. Laboratory test results on randomly selected sample coils were confirmed by an independent testing facility. The proposed corona-suppression systems were applied on thousands of production coils.     

PD pulse burst behavior of a transformer type synthetic organic ester fluid

The partial discharge (PD) pulse burst characteristics of a transformer type synthetic organic ester fluid were compared with those of an equivalent transformer type mineral oil. Wide and narrow bandwidth measurements were carried out to determine simultaneously the apparent charge transfers associated with the overall PD pulse burst as well as that of the individual discrete pulses within the PD pulse burst. The PD pulse burst behavior was found to be similar in both insulating liquids. The discharge cavity formation times ranged from 0.5 to 1.5 μs, while the charge transfers associated with the PD pulse bursts in the liquids were found to extend from approximately 5 to 30 pC.