600MW发电机组励磁变压器冷却系统问题分析及改造

对600MW发电机组励磁变压器冷却系统进行了介绍,分析了存在的问题,对励磁变压器冷却系统进行了改造,分析对比了励磁变压器改造前后的温度趋势。     

110kV新野变两台主变并列运行可行性分析

本文通过110kV新野变新改造两圈变压器与原三圈变压器并列运行的可行性进行分析,验证了两台变压器并列运行的可行性。同时根据实际运行情况对变压器并列运行时的环流进行了分析计算,证明了上述两台变压器并列运行的可靠性,并结合实际对变压器改造时应注意的问题进行了建议。     

电力变压器监造发现质量问题分析及措施建议

本文中作者对变压器监造中发现的质量问题进行了分析,发现了变压器制造中工艺控制和原材料组部件问题,提出了加强变压器质量管理的措施方法。     

基于IEC60076-15的SF6气体绝缘变压器的特殊性

对IEC60076-15《充气式电力变压器》中关于气体绝缘变压器的特殊要求进行了解读,同时对标准中没有提到的SF6气体绝缘变压器的相关问题进行了说明。     

确定用户所从属变压器的方法

对供电公司加装变压器后,由于记录不及时造成的不清楚用户所从属变压器的问题进行了讨论,并设计了用户从属变压器判别装置来解决问题,最后简述了后期维护问题.     

超高压变电站变压器差动保护的若干问题分析

本文通过对变电站变压器差动保护的影响因素进行分析,并提出了正确调试变压器差动保护的措施,有效保证了变压器顺利投入运行,而且对处理类似的变压器差动保护问题有很好的借鉴意义。     

大型变压器绝缘油含硫量测试方法及腐蚀性硫初步研究

针对电网大型变压器在运行中发现的硫腐蚀问题,初步探讨了变压器油硫腐蚀问题的各种影响因素;然后对变压器油中总硫含量及腐蚀性硫的测试方法进行了实验室研究和比较,提出了变压器油中总硫含量及腐蚀性硫测试方法的建议。     

大型变压器潜油泵的改造

为保证大型变压器的安全运行,对变压器潜油泵进行了改造,并对潜油泵的改造情况、改造后对变压器冷却器冷却容量的影响及改造过程中需注意的问题进行了分析。     

厂用变压器烧损事故原因分析及处理

本文通过对某电厂变压器烧损事故进行了详细分析，指出了变压器在内部结构上存在的问题，对变压器的结构和工艺改造提出了建设和方案，为变压器的制作和电力建设变压器的造型提供了良好的建议。     

变压器接线柱防止烧蚀装置的研究与应用

正1问题的提出变压器接线柱发生电弧烧损、锈蚀等问题后,需要将变压器停电、拆装后送至大修厂进行修复,更换变压器接线柱。维修变压器将产生大量费用,同时又影响了油井的运行时率,影响油井的产量。为解决这一问题,研制了变压器接线柱防止烧蚀装置。经实际应用,该装置有效解决了变压器接线柱本身的电弧烧损、锈蚀等问题,避免了因接线柱损坏而更换变压器的现象,可在变压器接线柱的使用领域推广。下面对这一装置进行具体介绍,供参考。     

750 kV变压器的研制

由保定天威保变电气股份有限公司自主研发的用于750kV输变电示范工程的4台750kV变压器产品均为一次试验、试制成功，各项性能指标完全满足或优于用户的要求，2005年9月26日顺利投产后运行情况良好。文章介绍了500MVA／750kV变压器的主要性能参数，分析了其成功研制750kV变压器的技术基础，对750kV变压器研制的关键技术，如产品总体结构、主纵绝缘结构、漏磁分析、防止局部过热、抗短路能力和制造与试验技术等进行了重点介绍。     

一种配电变压器热评估方法

针对配电变压器运行中的负荷特殊性和热传递微分方程参数难以确定的问题,提出了一种配电变压器热评估方法,分析了配电变压器热传递的动态过程,指出了传统神经网络难以适用于配电变压器热评估当中,考虑配电变压器三相负载系数,建立了配电变压器LSTM型循环神经网络热评估模型,对配电变压器顶层油温进行预测,达到配电变压器热评估的目的。算例表明:预测结果比热传递微分方程更接近实际情况,验证了该方法的有效性和实用性。     

Determination of phase angle and amplitude error of voltage and current transformers up to some 100 Hz for loss measurements on power transformers

Contents  For the load loss measurement of power transformers, current and voltage transformers with usually extremely low errors of phase angle and amplitude are used. However, even small errors of the measuring transformers may result in an error in the measured load loss. Therefore, national and international standards allow the correction of the measured value by the amount caused by phase angle and amplitude error of the measuring equipment [2–4]. The determination of the errors of phase angle and amplitude of measuring transformers is carried out on the basis of calibrated standard measuring transformers which are traceable to national standard equipment at rated frequency, e.g. at 50 and 60 Hz. For some applications – e.g. the load loss measurement of HVDC power transformers according to the draft of IEC standard 61378-2 [1] – a load loss measurement at frequencies other than rated frequency is required. For that, the errors of phase angle and amplitude of the measuring transformers must be known. This paper describes a method how to determine the phase angle and amplitude errors of the measuring transformers at arbitrary frequencies on the basis of the calibrated error values at rated frequency. Received: 9 August 2000     

基于电流互感器的长距离GIL短路故障在线定位方法研究

气体绝缘金属封闭输电线路(gas insulated metal-enclosed transmission line,GIL)内部发生短路故障后,如何在线准确、快速地确定故障位置,缩短故障后的检修时间,对电网的安全稳定运行至关重要。本文通过分析汇流排处电流互感器检测到的电流的特征,提出一种基于汇流排电流的长距离GIL短路故障在线定位方法。首先从理论上计算了GIL发生短路故障时,流过各电流互感器电流的特征;然后分析了GIL接入的架空线发生接地故障时,各电流互感器测得的电流分布,在此基础上,利用故障点两侧电流互感器的测量结果,制定出GIL短路故障的在线定位判据。还针对当短路故障位于GIL首/末段时无法精确定位的特殊情况,提出应缩短GIL首/末段两侧电流互感器的安装距离。本文提出的定位方法只与位于故障点两侧最近的两电流互感器测得的电流幅值有关,原理简单,结果准确。最后,以苏通GIL综合管廊工程为例,验证并说明了本文所提出方法及结论的正确性与有效性。     

An improved nonlinear thermal model for MV/LV prefabricated oil-immersed power transformer substations

The largest part of the investments of transmission and distribution systems is due to transformers used in changing the voltage level. The operating life of transformers is important due to their considerable economic impact on the power systems. To ensure the economical operation and secured service it is important to have knowledge about the insulation condition, operating life, and loading capacitance of transformer. The most important parameter in transformers life expectancy is the insulation temperature level, which accelerates the rate of aging of the insulation. The modeling of the energy balance and heat transfer of transformer is a major task in transformers thermal modeling. The aim of this paper is to present improved thermal models for transformers loaded at prefabricated MV/LV transformer substations and outdoor situations. The top-oil temperature is studied both for indoor and outdoor transformers and the thermal models proposed for them are compared. Since the thermal transfer is different for indoor and outdoor transformers considering their operating conditions, their thermal models differ from each other. The proposed thermal models are verified by the results obtained from the experiments carried out on typical indoor 30 kV/0.4 kV transformer stations at different operating conditions.     

核电站辅助变压器缺相保护研究

辅助变压器缺相检测是核电厂中最为关心的问题。一些核电厂的事件表明,变压器轻载时高压侧的缺相可能很难被现有的电气保护方案检测到。如果未能及时发现缺相状态,变压器不能与系统隔离,则可能会导致关键的电机驱动负载跳闸以及电厂安全系统的损失。然而,重负载到中等负载变压器的缺相条件可以通过传统的保护方案可靠地检测和保护。相反,轻负载或空载变压器可靠的缺相检测是具有挑战性的。本文介绍了核电站辅助变压器缺相的问题,提出了适用于大多数电力变压器的线路变压器缺相保护方案。新的方案使用光学电流互感器能够可靠检测重负载到中等负载变压器的缺相也可以可靠检测轻负载或空载的变压器缺相。     

Outage data analysis of utility power transformers based on outage reports during 2002–2009

Statistical analysis of failures and forced outages of power transformers constitute an important basis for asset management of these transformers. Results of the statistical analysis can be used, for example, to enhance utility reliability, influence transformer design and technology, and improve maintenance and condition monitoring practices. In addition, various methods for transformer reliability evaluation require that the expected values of component outage rates, outage durations, and repair durations be known. In this paper, outage data are obtained from the Egyptian Electricity Transmission Company (EETC). This work presents outage data analysis over eight years, from 2002 to 2009, for 1922 (average number) transformers in voltage populations ranging from 33 kV to 500 kV and MVA rating from 5 MVA to 500 MVA. Forced outages due to correct and false action of transformer’s protection systems are carefully considered. Outage data analysis is conducted according to two basic phases. In the first phase, failure and repair analysis of transformers is performed while in the second phase impact of transformer outages on customers is assessed. Percentage average number of failures (%AANF) and annual average repair time (AART) per transformer are used to represent the failure and repair data of power transformers. Two indicators are used to represent the impact of transformer outages on customer interruptions. These indicators are the annual average interrupted MW (AAIMW) and annual average customer-interruption duration (AACID). A summary of the main outcomes of the work presented in this paper is provided in the conclusions’ section; however, it is worthy to be mentioned here that the fire-fighting systems are responsible for the highest number of false trips in all voltage subpopulations except the 220 kV subpopulation where the dominant cause of false trips is the busbar protection. Therefore, it is recommended to improve the maintenance and design of this protection equipment to reduce the failure rate of power transformers.     

依托Hadoop架构的海量变压器实时监测与存储方案构建

随着智能电网的建设以及电力变压器在线监测技术的成熟,电力变压器在线监测数据呈现出体量大、类型多等特点。使用传统存储技术存储变压器在线监测数据,已不能满足实时、快速的需求。为此,设计基于Hadoop集群的变压器在线监测数据存储方案。该方案利用HBase(分布式列式数据库)具有快速实时读写数据的优势,将变压器在线监测系统采集的海量数据实时快速地存储。为能自动快速实时收集数据和避免因数据流过大造成系统崩溃,分别采用Flume(日志收集工具)和Kafka(分布式流处理平台)收集和缓存数据。以电力变压器在线监测的油色谱数据为例,验证了所提存储方案的可行性和有效性。     

Harmonic cancellation characteristics of specially connected transformers

Specially connected transformers such as V–V, Scott and Le-Blanc transformers are used to convert a three-phase supply into one or two single-phase supplies. These transformers are commonly used in the electro locomotive traction systems. This paper investigates the harmonic cancellation characteristics of such transformers. The results show that when two harmonic-producing loads are connected to each single-phase side of the transformers, the harmonics produced by the loads will cancel out at the primary sides of the transformers. The amount of cancellation is affected by transformer type and harmonic order. The study is performed for seven types of specially connected transformers.     

Scalable modeling with simple topology for stacked millimeter‐wave transformers

Scalable modeling with very simple topology for stacked millimeter‐wave transformers is presented. Because of high‐frequency effect and thick metal effect, the architecture is based on single‐π and double‐π network for transformers with turn ratio 1:1 and 1:2, respectively. The model parameters are extracted from two factors—the layout and process data. Simple and accurate expressions for the self‐inductance, mutual coupling inductance, and oxide capacitance are provided for the model. The proposed model is verified by 65 nm technology transformers. A very close agreement is shown for S‐parameter, self‐inductances of each coil, and coupling coefficient up to 110 GHz. Copyright © 2015 John Wiley & Sons, Ltd.