—In order to remove interference signal and external discharge signal during partial discharge test and get the effective signal of partial discharge, this paper carries out the research of typical interference signal mining and identification method for transformer partial discharge test. Firstly, based on the experience of previous researchers in partial discharge research, 47 feature parameters including statistical, texture and shape features are extracted, and the original feature space is constructed based on them, which provides the data basis for the optimization of the feature space and signal classification identification later. Next, the random forest algorithm is used to measure and rank the importance of the feature parameters, and the original feature space is optimized according to the ranking results to obtain the optimized feature space. Finally, the optimized feature space is used as the input of linear discriminant analysis algorithm and K-nearest neighbor algorithm to classify and identify the local discharge signal and typical interference signal, and the recognition accuracy of these two classification and identification algorithms is compared and analyzed, and the K-nearest neighbor algorithm is selected as the final classification and identification algorithm.

特高压变压器现场组装完成后,经加热干燥后的油温会影响变压器绝缘安全.针对传统热油循环法在寒冷地区现场加热特高压变压器效率偏低的问题,该文建立典型特高压交流变压器绕组流体-温度耦合数值模型,仿真分析1000kV特高压交流变压器热油循环加热及低频加热的温升规律,提出一种基于低频加热绕组热点温度反馈结果确定散热器油泵开启合理时间的变压器加热干燥方法,通过温升试验验证仿真模型与算法的可行性.结果表明低频加热配合散热器热油循环技术在7h时刻开启散热器油泵可以大幅缩短加热时间,提升加热效率.研究结果为寒冷地区特高压交流变压器的加热干燥提供了新的解决方案.

特高压输电技术的广泛应用已经为中国能源调配、大气污染治理、大规模新能源并网接入发挥了巨大作用,±1 100 kV昌吉—古泉特高压直流输电工程是目前世界上电压等级最高、输送容量最大、输送距离最远的输电工程。文中以该工程送端昌吉换流站HD换流变现场阀侧交流外施耐压及局放试验为研究对象,通过分析试验方法、试验布置、试验设备、试验参数、电场环境校核和试验结果,验证了采用免吊装的整装式试验平台在阀厅内开展该试验的可行性,提出了阀厅内开展该试验的电场校核空气最小净距应不小于7.5 m,该次试验的最终测得局放量小于150 pC,这也是全世界首次在阀厅内开展特高压换流变的该项试验,试验的方法和结果为阀厅内开展相关试验提供了解决方案。

本文中作者通过理论和试验研究分析了变压器剩磁对变压器绕组变形测量结果的影响,提出了一种电力变压器剩磁大小估算方法.

本文分析了一起由真空有载分接开关故障引起的变压器烧毁事故,指出了分接开关结构的不足之处,针对性提出了一种新型真空有载分接开关的设计思路,并制造了样机且已通过型武试验的考核.

电力系统三相之间存在轻微的不平衡现象,可能影响金属氧化锌避雷器(MOA)在线监测结果.提出了一种分析三相不平衡影响避雷器在线监测系统的评估方法:首先,按国标《GB/T 15543—2008电能质量三相电压不平衡》规定使用解析法计算三相不平衡电压向量,然后分析负序电压和零序电压对三相不平衡的影响.计算结果表明,系统最大相间偏差角度可取负序不平衡度与零序不平衡度之和的100倍.建议在TV二次侧直接提取三相电压作不平衡分析以提高MOA在线监测的准确度.

在荆门特高压站1号主变1000 kV无间隙金属氧化物避雷器进行直流参考电压及泄漏电流试验时,发现A相最下一节避雷器0.75倍直流8 mA参考电压下的泄漏电流I0.75U8mA实测值比初值(以出厂值作为初值)大了约42％,超出《GB/Z 24846-20091000 kV交流电气设备预防性试验规程》要求.为了查找原因,对该节避雷器进行了诊断性试验分析.各项试验结果表明,该节避雷器符合规程要求,并建议试验结果以国家电网有限公司企业标准《Q/GDW 322-20091000 kV交流电气设备预防性试验规程》为判断标准.

提出一种可识别接触状态的隔离开关分合位置判别方法,通过对隔离开关触头压紧弹簧压力和触头温度的综合判别来实现,根据压力的突变量大小来判别隔离开关处于分位还是合位,当判断隔离开关处于合位时,根据温度的高低来判断触头接触状态是否良好.该方法简单可靠,实时性好,解决了现有隔离开关分合位置判别方法不能判别隔离开关处于半合状态的难题,对于电网设备的安全稳定运行具有重要意义.

针对智能运检技术未形成统一标准,存在技术过于超前无法落地应用,或技术过于落后效果欠佳的问题,在深入分析当前运检技术的基础上,提出了适合于当前工业发展水平的智能运检模式,并解决了其中的几个核心问题,形成了成熟的解决方案.实际应用效果表明:所提出的智能运检方案能有效提升设备状态掌控水平,大幅提高现有劳动生产率.

The existing fault diagnosis methods of converter transformer windings under lightning impulse voltages have low sensitivity.It is difficult to diagnose fault types.The experimental data of the converter transformer under fault conditions are insufficient.It is difficult to study on the fault characteristics deeply.In view of the above problems,the reduced-scale model with a typical structure of converter transformer windings was designed and made with the scale of about 1/5.The lightning impulse tests were carried out under different fault conditions.The test data of different fault conditions were analyzed.The correlation coefficients for the transfer function of the fault condition and normal condition was calculated in different frequency bands and chosen as characteristic parameters.A fault diagnosis method was proposed based on the learning vector quantization network.The network was trained with characteristic parameters.Then the testing samples were used for testing.The results show that the correlation coefficients in specified frequency bands can reflect fault characteristics.The diagnostic accuracy of the testing samples is 98.2％.It verifies the effectiveness of the fault diagnosis method.

阐述了在现场进行特高压换流变压器空载试验的主要困难,分析了通常用于大型变压器现场空载试验的电容补偿法的缺陷,给出了实例.

为了研究800kV换流变压器缩比模型在雷电冲击电压下的电压分布特性,采用多导体传输线(MTL)的方法,建立了双绕组数学模型,并将计算结果与仿真结果进行比较,证实了此方法的正确性.

特高压换流变压器的现场局部放电试验电压等级高,现场环境复杂,试验要求高。在对称加压方式下,存在被试品端部电位差大,电抗器补偿调节和电压电流测量不便等问题。为获得合理的电抗器补偿方式,减小对称加压方式下各端部电压差,研究了特高压换流变压器电容网络的等效方法,并根据现场试验的参数进行仿真研究,获得了补偿电抗器参数。

In this paper, the influence factors of transformer core saturation in low frequency short circuit method are studied. A method to draw the B-H curve of the saturation state of the iron core and the formula for calculating the critical frequency of iron core saturation are presented in this paper. The formula is verified in experiments and the field application of the low frequency heating of the UHV converter transformer.

相似理论是试验分析中被广泛采用的应用科学方法,以相似理论为基础确立缩比关系有助于从模型测试结论推导至实际模型结论,采用缩比模型试验用于变压器的设计或者特性研究具有良好的经济意义和价值.本文首先对相似理论的基本定律进行了介绍,然后以电力变压器为研究对象,以尺寸和电流幅值作为基本缩比因子推导得到变压器的缩比关系式,基于Ansoft有限元仿真软件,建立了180匝的变压器原模型和缩比模型,最后进行了电磁场数值仿真比较.研究结果表明,原模型和缩比模型的磁场云图分布规律完全相同,对应时刻及对应位置上的磁感应强度幅值满足缩比关系,验证了本文推导的缩比关系.

提出了一种基于奇异值分解的变压器局部放电模式识别方法.通过搭建人工缺陷实验环境并采集样本数据,计算每个样本的统计特征参数,构成实验数据的样本矩阵.对样本矩阵进行奇异值分解,判断保留矩阵的特征是否明显,确定最佳保留矩阵的阶数,从而得到降维后的类型特征空间描述矩阵和类中心描述向量组.对现场采集的样本数据进行计算得到待分类的样本向量,并用类型特征空间描述矩阵进行线性变换,然后计算变换后的向量与类中心向量组中每个向量的距离,从而得到分类的判断结果.该算法简单而且高效,能够实现局部放电检测中各种放电信号的有效区分,局部放电模式识别召回率约为91.3％.

An experimental scale-down model of ultra high voltage direct current converter transformer is designed and manufactured to study the wave process in the winding under impulse voltage. Nine outgoing lines are configured on different winding coils of the scale-down model. The voltage waveforms of different outgoing lines are obtained by the lightning impulse voltage. The simulation model of scale-down transformer is established to calculate the distributed parameter matrices through the finite-element method. The equivalent circuit of the transformer winding is proposed to calculate the voltage waveforms and the potential gradient distribution. The comparative analysis of test and simulation results shows that the oscillating voltage occurs in the winding, and the simulation results can reflect the wave process characteristics.

针对电力设备在操作冲击电压下产生局部放电现象,构建了油纸绝缘气隙模型,基于局部放电发展过程特征变化,分析了放电重复率和放电量.