油浸式电力变压器冷却装置效率计算

变压器冷却装置(冷却器、散热器)效率不足时,将影响到变压器的正常运行。对此,本文提出计算变压器冷却装置效率的方法,开发计算软件。效率计算结果可作为冷却装置清洗的依据。     

地区电网采用高效变压器的节电潜力分析

对配电变压器的运行损耗进行了深入的分析,并根据3种变压器损耗算法建立了3种节电潜力评估模型。以广东电网公司某供电局的电网侧和该地区的用户侧配电变压器为例,分析了该地区电网更换低压配电变压器的节电潜力,结果表明,该地区电网低压配电变压器节电潜力巨大,若进行更换,可获得可观的效益。     

Retrofilling conditions of high voltage transformers

This article reports the procedures and preliminary tests related to the retrofilling of a perchlorethylene-base d fluid (Transclene^TM) filled transformer. Two insulating liquids, a mineral oil and an ester liquid that seemed to be suitable for this retrofilling, were investigated, In order to examine long-term effects, the investigations were performed on new samples as well as on samples subjected to severe ageing conditions. To simulate real operating conditions, the temperature was varied between O and 100 °C with different water contents     

关于DL/T 985《配电变压器能效及技术经济评价导则》的编制说明

为了给国内的变压器用户、变压器制造商和设计单位提供一种简洁且行之有效的评价变压器能效的技术经济手段，本导则提出了基于技术经济效益分析的配电变压器能效评价方法及相关计算公式，供变压器用户在确定变压器能效时采用或参考。     

传递函数法用于变压器冲击试验的故障诊断

利用传递函数法进行变压器故障判断时,传递函数的计算直接影响判断的准确性,试验数据的分析表明,在相同的试验条件下,合理选择采样率和记录长度并对采集到的数据进行滤波将有利于传递函数的计算,从而得到更准确的试验结果。     

Exergoeconomic methodology applied to energy efficiency analysis of industrial power transformers

This work aims to develop a methodology based on exergoeconomic models to be used as a tool in the analysis of energy efficiency transformers arranged in distribution networks. The exergetic modelling method adopted is based on building of thermoeconomic functional diagram that will be used later as a reference for defining the allocation of costs associated with the transformer choose for analysis. The exergetic cost for each compound of transformer has a tendency to decrease because the value aggregated by device operation. Also exergetic production cost and final cost of power output have this same tendency. Finally these costs provide a payback period less than a year, which makes viable the investment in this system with operational set points.     

Background information on high temperature insulation forliquid-immersed power transformers

The availability of insulation materials having a higher temperature rating than cellulose has led to the design of high temperature power transformers for specialized applications where size and weight are important considerations. Such applications include traction transformers, mobile transformers, and power transformers with special loading requirements. Even though such equipment has been in use for many years, there are presently no standards which address high temperature materials in liquid-immersed transformers. Recognizing this deficiency, the IEEE Transformers Committee has established a Working Group to investigate what standards or guides could be formulated. As a first step, the Working Group has prepared this “state-of-the-art” paper to document background information on the materials and their application. It is hoped that discussion of this paper will help to establish future directions for standards     

高频变压器漏电感简化计算方法

绕组高频效应使高频变压器漏感参数具有复杂的频变特性.但传统算法并未考虑漏磁的频变特性导致计算精度较差,而现代计算方法单纯地套用Dowell公式,并且没有考虑不同绕组结构的漏磁分布特性,导致公式通用性较低,在实际工程中难以使用.本文在对高频变压器实际漏磁分布模型分析的基础上,提出一种高频漏磁分布等效变换模型,并基于磁链分...     

主变500kV环氧树脂浸纸套管介损异常原因研究

2001年至今,国内有多家电厂主变500 kV的12具环氧树脂浸纸套管发现介损异常,其中3具已予以更换.通过理论分析、现场实测,以及实验室研究,揭示了环氧树脂浸纸主变高压套管介损异常的原因主要是由于两种不同介质的界面极化所致,建议只要采取额定运行电压下持续运行一段时间的方法,即可使其介损恢复正常.对于该型套管的介质异常应.同时监测介损异常套管的电容量,以作出正确的判断.     

Reliability evaluation of distribution transformers with high penetration of distributed generation

In this paper, a novel methodology is presented to evaluate the micro-grids reliability concerning the dynamic thermal aging failure of transformers. The widespread presence of distributed generation (DG) units reduces the loading passing through the distribution transformers and consequently improves the dynamic thermal failures. The system reliability is investigated for various penetrations of different scenarios from the view of DG technologies. The introduced method is applied to a realistic distribution system comprising different distribution transformers in Iran. The sensitivity analysis corresponding to adequacy indices such as expected energy not-supplied (EENS) based on DG penetrations is performed. By the use of the novel methodology proposed, it is possible to recognize how different DG technologies and penetrations can impact on the system reliability. The results demonstrate that the diesel generators and hybrid systems including diesel generators, photovoltaic units, and wind turbines are the most promising DG technologies to improve the transformer failures and the reliability of micro-grids compared with renewable DG units.     

高阻抗变压器附加损耗增大的原因分析

由于变压器机械强度问题日益突出,越来越多的用户采用高阻抗变压器。但高阻抗变压器的附加损耗较大,如何降低其附加损耗是高阻抗变压器设计、制造中应着重解决的问题。通过对高阻抗变压器附加损耗增大的原因的理论分析,提出了实际生产中降低附加损耗的措施。     

Superconducting transformers

The technological progress of power frequency AC superconductors is remarkable and application studies are being carried out, targeting AC superconducting (SC) machines for power systems. The introduction of SC machines into the power system needs to display the merits of not only efficiency improvement, but also power system performance and operation. A conceptual design for a coreless superconducting transformer (SCT) is made, based on the above views and its merits evaluated. A future possible power system employing coreless SCTs is presented, and consideration is given to the actual service in a future power system     

一种双向谐振型高频直流变压器通用参数设计方法

交流微电网和直流微电网之间多通过电力电子变压器(PET)构成交直流混合微电网以减少额外的电能转换环节.但是PET中高频变压器的谐振参数常常限值了效率的提升,且谐振拓扑的细微变化也会进一步加剧参数设计的难度.针对该问题,提出一种面向交直流混合微电网(HADM)的双向谐振型高频直流变压器(HFT)通用型参数设计方法,明确只...     

Current transformers and coupling-capacitor voltage transformers inreal-time simulations

This paper describes two models: a saturable current transformer model (CT) and a wide-band coupling capacitor voltage transformer suitable for real-time transients simulation. By using very efficient network reduction and network synthesis techniques, the operations count for these models is kept to a minimum. The accuracy of the models has been tested in connection with our real-time transients simulator RTNS and compared to conventional EMTP models     

Multiband current transformers

The design and principle of action of the new multiband transformer of a current is considered in which the expansion of the top range of measurements is carried out by creation against a magnet driving force in the closed core.     

环氧浇注干式变压器与其他类型干式变压器的比较

干式变压器的发展及类型1.历史回顾及干式变压器的发展｛有下列类型: 不带填料的薄绝缘注型式(用模具)环氧浇注式 带填料的薄绝缘注型式(用模具) 绕包式(不用模具)绝缘等级主要为F级,但也有少量H级的(图1)。 采用NOMEX纸的开敞通风式(OVDT) H级干变(用VPI)工艺(图2) 采用NOMEX纸的VDT(或VPE)包封式浸渍(漆)式 H级 干变(用VPI工艺) 不用NOMEX纸的OVDT H级干变(用 Ⅵ工艺)(如MORA技术)图1 环氧浇注式H级干变…     

Application of common transformers faults diagnosis methods on biodegradable oil-filled transformers

Due to environmental concerns regarding the use of mineral oil, biodegradable oil is increasingly being used as an alternative dielectric fluid. This paper presents results of experiments performed in the laboratory on the use of biodegradable oils for transformer application. The investigations cover two important diagnostic techniques for insulation assessment: (i) an investigation of partial discharge (PD) activity and characteristics in such oils and (ii) an investigation of the standard hydrocarbon dissolved gas products produced due to transformer faults. The fundamental aim of the investigation was to provide information as to whether the existing analysis techniques of PD fault pattern recognition and dissolved gas analysis methods, developed for mineral oil, are valid when used for insulation assessment with biodegradable transformer oil. The experiments were conducted on test samples to simulate three common types of transformer faults: low-energy PDs, high-energy arcing/sparking, and overheating. For the purpose of comparison, the same tests were performed using a mineral oil (Shell Diala MX) and a biodegradable oil (Envirotemp FR3). Also, each oil type was tested at three different moisture levels and with or without the presence of solid insulating materials (pressboard). PD activity was monitored using the standard IEC60270 phase-resolved analysis method. The fault gases produced were extracted and analysed by standard gas chromatography methods. Test results indicate that the PD phase resolved patterns are, in general, similar for the two oil types and thus existing PD pattern interpretations can be used to distinguish different types of PD faults, e.g. corona versus surface discharges. However, the values of various discharge quantities (PD magnitudes, repetition rate, current, etc) are very different under the same test condition. The quantities and the trend of dissolved gases for faults in biodegradable oil are substantially different compared with mineral oil. For the PD fault, biodegradable oil was found to release only a limited number of gases. For arcing and overheating faults, the main key gas produced is different between the two oils. Also, the presence of cellulosic materials such as pressboard influences the extent of hydrocarbon gases dissolved in the oil. It was found that for biodegradable oil, fewer amounts of gases are produced as the oil gets wetter.     

Single-phase insulator transformers

To show that voltage surges are effectively transmitted between the windings of insulator transformers, a relatively simple and functional test was prepared. The test applied differential-mode voltage surges with small amplitudes to the primary winding of three different types of single-phase no-load insulator transformers. The differential-mode was selected based on the fact that this mode is much more frequent than the common-mode.     

高效光伏逆变器综述

介绍了光伏逆变器漏电流相关标准,分析了无变压器隔离的光伏逆变器的几种典型拓扑、工作原理与优缺点,阐述了多电平拓扑在光伏逆变器上的应用及其对提高效率的贡献,总结了高效功率器件在光伏逆变器上的应用,说明了调制和控制算法应用于光伏逆变器的必要性,展望了下一代逆变器的发展趋势。     

多组变压器在低压大电流开关电源中应用的研究

本文介绍了一种低压大电流开关电源采用的变压器结构，并与传统的一组变压器结构进行了比较。以12V／1000A移相全桥ZVS开关电源的PSPICE仿真验证了这种结构的优点。