Defects in GIS can be effectively detected by detecting the partial discharge (PD). The common methods of detecting partial discharge are pulse current, ultrasonic and UHF (ultra-high frequency). However, the results of different methods may be different due to the different physical quantities detected. It is important to research the differences between the PD detection methods for the PD detection and analysis. In this study, we designed metal protrusion defects in GIS, including protrusion on the conductor and enclosure. Then, we detected the PD of defects using pulse current, UHF and ultrasonic methods at the same time. The PRPD patterns, maximum discharge amplitude of different defects and PD inception voltage (PDIV) detected by the three methods were analyzed. The PRPD patterns and discharge amplitude of the different methods were very similar to each other, but the PDIVs were different. It can be concluded that the process from the PD inception to breakdown can be divided into four sections based on the PRPD and the maximum discharge amplitude. The similarity between the three methods is because their signals are all related to the pulse current during the PD process, and differences in their PDIVs are caused by the differences in sensitivity. The sensitivity of the pulse current is the lowest among the three methods due to its poor anti-jamming capability. The sensitivity of UHF is higher, and that of ultrasonic is the highest.

In order to prevent the impact of extreme rainstorms on power equipment in substations, accurate and reliable real-time precipitation estimates are essential for emergency flood control in substations and to ensure stable grid operation. Compared with ground precipitation measurements, weather radar echo-based monitoring can effectively utilize the latest available information for short-term prediction. In this paper, a deep learning model based on spatio-temporal attention mechanism is proposed for precipitation estimation. The model extracts the rainfall intensity resolution at spatial granularity in high-resolution radar echo maps using separable convolution operations in UNet deep networks, combined with an attention mechanism to capture the relevant features at temporal granularity. To evaluate the effectiveness of the proposed model, a comparison is made with other deep learning models in terms of probability of detection, false alarm rate, critical success index and Heidke skill score. Experimental results on precipitation data from a meteorological institute show that the proposed model has better performance in short-time precipitation forecasting compared with traditional methods.

In severe convective weather, transmission lines are prone to lightning strikes, wind swings, rain flashes and other faults that threaten the safe operation of the power grids. To overcome the problem that the existing nowcasting cannot fully meet the demand for refined weather forecasts for transmission line risk warning, a deep-learning-based nowcasting model of severe convective is constructed in this paper. The model is built by using meteorological radar echo image, assimilated data of wind speed and rainfall, lightning location data of the power grid and it is used to carry out early warning of transmission line risks. First, an long short-term memory (LSTM) network-based forecasting model of severe convective meteorological elements is constructed by taking the meteorological radar echo and its time-series extrapolation data as inputs, and assimilated data of wind speed and rainfall, lightning density, lightning current intensity as outputs. Then, combined with the wind, rain, and lightning forecast output from the model, the risk of wind swing, lightning strike, and tower collapse in the transmission corridor grid is evaluated. The fault probability of the transmission line is calculated in a comprehensive way for risk early warning. Finally, a case of successful early warning of severe convective weather processes in a province in September 2023 is demonstrated, which demonstrates the ability of the proposed method to improve the risk early warning capability of transmission lines under severe convective weather.

针对南阳站中国首台/套户外1 100 kV特高压气体绝缘金属封闭输电线路(GIL),文中首先介绍了户外特高压GIL管壳结构的几何构型特点和静力学服役特性;然后,结合相关行业标准,从弹性力学角度分析评述了户外特高压GIL管壳结构的柔性设计技术和应力强度分析理论,并梳理了南阳站户外特高压GIL管壳结构强度试验的不足之处;最后以南阳站1 100 kV户外GIL管壳结构为试验研究对象,于中国首次进行了基于温升应变的日照环境下户外GIL壳体结构的温升形变试验研究,并应用热应力和第三强度分析理论,分析评价了管线结构的温升形变和强度特性,为类似GIL管壳结构的柔性设计和静力学强度评价提供了相应的试验分析基础和技术指导.

为分析大区域电网对埋地油气管道的持续干扰,本研究在分析持续干扰电压幅值随线路和管道间距变化规律的基础上,提出利用阈值确定大区域电网建模边界,以构建电网对管道持续干扰分析模型的方法,并建立了计算截断误差的概率模型.结果表明:由距离管道较远线路产生的小幅值干扰电压分量的向量和近似为零,且这些干扰电压分量向量和的模值近似服从瑞利分布;在分析线路平均间距大于200 m的220 kV电网对管道的持续干扰时,仅考虑管道两侧4.20 km内导线按ZB型杆塔排列的线路,4.10 km内导线按ZM型杆塔排列的线路,10.65 km内导线按SZ型杆塔排列的线路,11.93 km内导线按SSZ型杆塔排列的线路,11.84 km内导线按SSSZ型杆塔排列的线路,即可使截断误差有95％的概率小于2.23 V.

雷击输电杆塔时,通过接地装置流入大地电流和流过地线的电流都会在附近埋地管道的防腐层上形成干扰电压,对管道形成威胁.本研究利用频域矩量法结合时频转化的方法,建立了雷击输电杆塔时附近埋地管道防腐层电压的计算模型,给出了土壤电阻率、管道与输电线路的间距、管道尺寸、防腐层电阻率和防腐层厚度对防腐层电压的影响,并对安装排流带和改变杆塔接地装置结构的防护措施的效果进行了计算,结果表明合理的布置排流带和改变接地装置结构,可降低管道防腐层的电压.

新型三元混合绝缘油具有优良的热稳定性及抗老化性,可以有效延长老旧变压器绝缘系统的使用寿命.在不改变原有结构的情况下,将运行20年的35kV老旧矿物绝缘油变压器绝缘介质直接更换为新型抗老化三元混合绝缘油,并进行试验对比研究.结果表明,注入三元混合绝缘油的老旧变压器完全满足矿物绝缘油变压器相关试验要求,且挂网运行期间各项试验指标均满足运行标准要求,并不影响变压器的实际运行特性,这对于延长在运老旧油浸式变压器使用寿命具有一定的可行性.

当雷击中输电杆塔时,在雷电流的阻性耦合和感性耦合作用下,埋地管道上的感应电压会对防腐涂层造成威胁.笔者建立了管道与输电线路平行的模型,研究了 土壤电阻率频变特性对管道感应电压的影响.计算表明,土壤电阻率频变特性会使管道金属电位和防腐层电位均有所下降,由于两者下降的程度相近,导致管道防腐层两端承受的电压无明显变化,而绝缘接头的电压则有明显的降低.

以SF6为绝缘介质的全封闭式组合电器(GIS)已广泛应用于电力系统.由于金属微粒、绝缘子缺陷等,可能引发设备发生局部放电,甚至造成停电事故.为及时、有效辨识设备内部局部放电故障类型,本文在积累的大量SF6局部放电分解特征组分数据的基础上,提取出表征典型局部放电故障特征的分解特征组分,采用"故障数据分布密度"标准差最小化的原则来确定反映故障状态的主要特征量权重,最终建立了针对SF6气体绝缘设备局部放电的三角形诊断法,实现了典型局部放电故障的诊断.通过已有实验和现场数据,对该方法的诊断准确性进行测试,结果表明该方法可以有效识别局部放电故障并精确区分其放电类型,诊断准确率可达90％.

模拟了河南典型土壤介质环境,研究了典型"金属引下线(镀锌钢)-石墨接地网"之间的电偶腐蚀行为.结果表明:在模拟土壤介质工况条件下,金属引下线和石墨接地网之间的电位差约为700 mV,具有显著电偶腐蚀倾向,其中,引下线镀锌钢的自腐蚀电位更负,为电偶腐蚀阳极,腐蚀进程将被加速;电导率和含氧量对这两种材料间的电偶腐蚀行为均有显著影响;随着电导率和含氧量的升高,电偶电流密度均增大,在含氧量15％和电导率1 000μS/cm条件下,相比无偶接试样,其电偶腐蚀加速倍率分别达到13.36和5.18,电偶加速效应明显;面积比的升高对电偶腐蚀也具有明显的促进作用;本研究条件下上述两种材料间的电偶腐蚀敏感性等级均达到最高级E级.在新型石墨接地网装置中,镀锌钢引下线存在较高电偶腐蚀风险,在实际使用中应尽量避免上述两种材质的组合,在无法避免的情况下,应对其采取合理的防护措施.

对接地网进行准确的腐蚀诊断是电力工程中十分关注的问题.为了解决接地网腐蚀诊断过程中计算方程组欠定所导致的诊断精度不高,效果不理想的问题,文中提出一种基于支路电压扰动的接地网腐蚀诊断方法,该方法通过接地网腐蚀前后支路电压的扰动实现腐蚀缺陷支路的定位和腐蚀程度的判断.文中首先理论分析接地网支路电压对支路电阻的灵敏度;其次,利用支路电压扰动特性,建立接地网腐蚀诊断模型,得出支路电压扰动峰值位置、大小与接地网腐蚀支路位置和腐蚀程度的映射规律;最后,实验验证了该方法能够对接地网的支路腐蚀进行有效的诊断.

输电线路舞动是指架空输电线路导线发生偏心覆冰后,在风的激励下产生的一种低频率、大振幅自激振动现象.输电线路舞动严重威胁电网冬季运行安全,易造成倒塔、断线、送电中断等重大电网安全事故,是亟需解决的世界性难题.我国是输电线路舞动灾害的高发区,而河南是舞动较为为严重的地区.因此,解决舞动问题对保障电网安全、促进河南经济发展、实现国家能源安全具有重要意义.

Transmission lines and buried oil and gas pipelines are very similar in the principle of selecting paths, the situation that transmission lines and buried oil and gas pipelines are parallel for a long distance or intersected occurs constantly. When the transmission line is struck by lightning, the safety of buried oil and gas pipelines will be threatened. In this paper, CDEGS is used to study the influence of uniform soil, horizontal stratified soil and vertical stratified soil on the pipeline induced voltage when the buried oil and gas pipeline is parallel to the transmission line. It can be seen from the study that the maximum coating voltage along the pipeline is mainly related to the soil resistivity around the ground device of the tower struck by lightning. In the design stage of the pipeline and transmission line, the field investigation should be done and the transmission line should be arranged on the side with low soil resistivity.

变电站接地网故障诊断技术主要包括接地特性参数、电阻网络节点、磁感应强度、电化学分析和超声导波检测等5种常用方法.对基于信号输入输出状态响应检测的接地网故障诊断技术进行了探讨,提出了扫频法即扫频阻抗和幅频响应测试技术.利用搭建的测试系统,对8m×8m(2m等间隔)规格敷设的接地网,在设置模拟脱焊、导体断裂以及导体腐蚀缺陷3种工况下,完成了试验测试.对4通道高频采样获取的激励电流和三个响应电压波形,进行了扫频阻抗和幅频响应曲线分析.相关系数分析结果表明:设置导体断裂时的扫频电压波形、幅频响应曲线与无缺陷时的波形曲线有细微区别.

Firstly, the insulation structures of oil-immersed current transformer (TA) and SF6 TA are introduced. And then, the causes of TA insulation breakdowns are analyzed based on an investigation of the insulation faults of TAs occurring in several cases. It is concluded through further disintegration examination that the seal failure is the root cause for insulation fault. Lastly, operation recommendations and precautions are presented for seal failure caused by the metal expander leakage of oil-immersed TA and the rupture disc damage of SF6 TA.

通过在变压器油中添加热导率高的氮化铝(AlN)陶瓷纳米颗粒,可以提高基础油的热导率;但随着混合油的热导率增大,其电气性能有所下降.文中选取的添加浓度,在满足设备电气性能的同时,也使混合油的导热性能大为提升.文中提出了纳米油变压器实际应用方案,通过试验研究了纳米油变压器自然负载、低负载运行及过负载运行工况等实际挂网运行性能,对比研究了纳米粒子的添加对变压器稳态和短时温升提升效果的差异,研究发现氮化铝纳米陶瓷粒子的添加能够加强变压器内部热量的传导,提高变压器的散热效率,但在较低的负荷工况下稳态温升降低幅度小于变压器高负载工况下短时温升的降低幅度.

The UHV transmission lines usually have large regional spans and involve various weather conditions, which will have different effects on the circuit design and electromagnetic environment. However, the existing research lacks the ion flow field analysis of AC and DC parallel lines under different weather conditions. Hence, we studied the distribution law of the ion flow field of ±800 kV DC and 500 kV AC parallel transmission lines under different weather conditions, and compared the calculated results with measured results. First, we used the meshless method to model the ion flow field of AC and DC parallel lines in different weathers. Then, the influence of environmental factors on the ion flow field was analyzed. The effects of temperature, humidity and haze on the distribution of the ion flow field were obtained based on long-term monitoring and measurement. Results show that the ion flow field of the theoretical calculation results was basically in accord with the actual measurement. The ion flow field of parallel lines increases with the rise of temperature, first increases and then decreases with the rise of humidity, and increases with the rise of haze.

DL/T 266-2012《接地装置冲击特性参数测试导则》规定了电力系统中发电厂、变电站和输电线路杆塔的接地装置冲击特性参数测试的一般原则、内容、方法和判据.在该标准的基础上,对基于信号输入输出状态响应检测的接地网故障诊断技术进行了探讨,提出了冲击法即冲击阻抗和幅频响应测试技术.利用搭建的测试系统,对28 m×25 m(不等间隔)规格敷设的接地网,在设置模拟脱焊、导体断裂以及导体腐蚀缺陷3种工况下,完成了试验测试.对多通道高频采样获取的激励电流和响应电压波形,进行了幅频响应和冲击阻抗曲线分析.结果 表明:设置导体断裂时的冲击电流电压波形、幅频响应曲线与无缺陷时的波形曲线有细微区别.

基于电网络理论分析方法,设计开发了一套基于循环电压测量法的接地网故障定位装置,实现了接地网的小电流注入、节点毫欧级别低电位和支路毫欧级别的低阻抗的自动循环精确测量;同时利用多态近似解方法求解支路阻抗变化,实现故障精确诊断及定位.通过开展系统的实验室和现场试验测试,装置的可行性及准确性得到了验证.

文中对近年来铁心电抗器振动与噪声的研究进行了总结.考虑电抗器铁心材料及结构特点,得出硅钢片磁致伸缩效应、铁心饼间电磁吸引力及绕组受安培力作用是引起电抗器振动的主要因素.分析电抗器铁心振动时位移和加速度情况,测量超/特高变电站内电抗器设备噪声的声级及频谱分布,得出影响电抗器振动与噪声的主要因素包括激励源大小、选材及制作水平和安装运行环境.通过开发高效隔振器及高性能隔声装置能够有效减弱电抗器振动传递与噪声传播,设备主要材料及结构改进也能在一定程度上降低设备运行时的可听噪声.