Research Progress of On-line Monitoring Technology for Electromagnetic Environment of Power Transmission and Transformation Projects

Based on the collection of relevant literature and cases,the research and application status of on-line monitoring technology for electromagnetic environment of power transmission and transformation projects at home and abroad were introduced.Moreover,the problems existing in the on-line monitoring of electromagnetic environment were expounded,and the development prospect was forecasted.

Reliability of Power Transmission and Transformation Facilities in 2010

Through the reliability analysis on transmission and transformation facilities with 220 kV or above voltage level in China in 2010, particularly by investigating the planned and unplanned outage of transformers, circuit breakers and overhead transmission lines with 220 kV, 330 kV and 500 kV level, the weak parts that may influence the operational reliabilities are figured out from technical and liability causes. Moreover, through the research on the device models and comparison of performance indices between domestic and imported devices, the trend of the reliability changes are identified so that the references can be provided for power enterprises to determine corresponding effective reliability measures during planning, design, implementation and production stages.

Power Transmission and Distribution Equipment in Steady Progress

SEC is not only one of the largest enterprise groups in China that engaged in designing and manufacturing of power generating equipment, but also is noted for designing and manufacturing power transmission and distribution equipment. Shanghai Power Transmission and Distribution Equipment Corporation is a subsidiary of SEC. It consists of key enterprises, including Shanghai Hua Tong Switchgear Works, Shanghai Relay Plant,Shanghai Instrument Transformer Works, Shang-

Manufacturing Development Emphases on Power Generation and Transmission Apparatus in 11th Five-Year Plan Period and Prospect to the Year 2020

Based on predictions on Chinese power development in the coming 20 years, this paper introduces the emphases and key technologies in power sources and power network construction, and puts for ward the major tasks and technological orientation for machinery manufacturers to supply qualified equipment to China power industry.

Basic Concept and Theoretical Study of Condition-based Maintenance for Power Transmission System

状态检修背景下,为解决电网运行整体与输变电设备个体之间的矛盾和冲突,在已有研究成果基础上,提出电网状态检修的概念,在输变电设备状态检修决策过程中,给出电网故障风险和电网检修风险的定义以及相应的量化表达式。依据设备状态预测,以电网故障风险和电网检修风险的和最小为目标,将设备检修、运行以及电网整体性能在概率引导下相互牵制,形成电网状态检修的数学模型,并给出相应的解决方法。最后,为验证该理论研究的可行性,分别以可靠性测试系统RBTS-BUS6和IEEE-RTS79系统为例,对各种情况进行分析,体现了预期的效果,并期望为电网检修与运行协调决策理论的深入研究提供必要的理论基础。

High Precision Ultrasonic Guided Wave Technique for Inspection of Power Transmission Line

Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.

Combined approach for analysing evolutionary power spectra of a track-soil system under moving random loads

The pseudo-excitation method combined with the integral transform method (PEM-ITM) is presented to investigate the ground vibration of a coupled track-soil system induced by moving random loads. Commonly in the track model, the rail, sleepers, rail pads, and ballast are modelled as an infinite Euler beam, discretely distributed masses, discretely distributed vertical springs, and a viscoelastic layer, respectively. The soil is regarded as a homogenous isotropic half-space coupled with the track using the boundary condition at the surface of the ground. By introducing a pseudo-excitation, the random vibration analysis of the coupled system is converted into a harmonic analysis. The analytical form of evolutionary power spectral density responses of the simplified coupled track-soil system under a random moving load is derived in the frequency/wavenumber domain by PEM-ITM. In the numerical examples, the effects of different parameters, such as the moving speed, the soil properties, and the coherence of moving loads, on the ground response are investigated.

Towards a (More) Electronic Transmission and Distribution (eT&D)

The challenges and the path towards a(more)electronic transmission and distribution(eT&D)is presented in this paper.The challenges are first identified together with key stakeholders in the drive for grid modernization.A fundamental question is then asked about the investment priority.Six basic characteristics are reviewed,leading to the composition of structured microgrids as the basic functional cell of a modern grid.One example of fractal radial structure and one fractal meshed structure are presented.The likely evolution path is then proposed together with basic technology sets.Specific foundation technologies are discussed in detail,including adiabatic power conversion,3MC technology,medium voltage conversion,distribution-level electronic power transformer and FACTs hardware integration,and back-to-back converters as a universal interconnect element.The rapidly emerging on-wire sensing technology is also discussed.It is pointed out that the distribution-level large electronic power transformer will provide a key component to enable hybrid ac/dc grid flow control and ancillary support for a flexible electronic transmission and distribution(eT&D)systems.

柔性低频输电系统的主变稳态负序差动保护

为了解决常规纵差保护难以适用于低频系统的问题,通过分析低频系统的序分量抑制策略,并根据低频系统故障进入稳态后单侧有负序注入的特征,提出一种基于稳态负序分量的主变差动保护方法。为防止该差动保护在区外故障时因电流互感器饱和出现误动,通过对比分析三类制动电流计算方式的制动性能,得到了差动保护的制动方程和制动系数。为解决励磁涌流、电流互感器断线可能导致误动的问题,提出了相电压突变量的差动保护开放条件。仿真分析表明,该方法能够灵敏反映区内金属性故障及轻微故障,在区外故障伴随电流互感器饱和时有可靠的制动裕度。

0.2~2.0GHz100W超宽带GaN功率放大器

设计并实现了一款基于0.25μm GaN高电子迁移率晶体管(HEMT)工艺的100 W超宽带功率放大器。基于SiC无源工艺设计了集成无源器件(IPD)输入预匹配电路芯片;设计了基于陶瓷基片的T型集成输出预匹配电路;基于建立的传输线变压器(TLT)的精确模型,设计了宽带阻抗变换器,在超宽频带内将50Ω的端口阻抗变换至约12.5Ω,再通过多节微带电路与预匹配后的GaN HEMT芯片实现阻抗匹配。最终,以较小的电路尺寸实现了功率放大器的超宽带性能指标。测试结果表明,功率放大器在0.2~2.0 GHz频带内,在漏极电压36 V、输入功率9 W、连续波的工作条件下,输出功率大于103 W,漏极效率大于50%,输入电压驻波比(VSWR)≤2.5。

基于数字孪生技术的新型电力系统数字化

随着“双碳”目标的提出,大规模的清洁能源、电力电子设备和新型负荷将接入电力系统,传统的电力系统管理控制模式难以应对双侧随机性、波动性增强等问题,电力系统的安全稳定运行迎来巨大挑战。数字孪生技术作为重要的数字化手段,成为电力系统转型升级新方法。针对新型电力系统内在机理发生的深刻复杂变化,综述了数字孪生的发展历程以及其在电力系统领域的研究现状,并从新型电力系统数字化需求、数字建模方法、数字化平台建设3个层面研究了电力系统数字化转型进程。最终,提出了以数字孪生技术为核心的新型电力系统建模方法和框架。

基于垂直中继的U型高压线路无线供电系统设计

为解决110 kV输电线路杆塔侧在线监测设备的供电问题,文中提出一种基于垂直中继的U型高压线路无线供电系统。首先结合互感耦合理论与有限元仿真,提出U型无线供电系统的整体设计方案,实现杆塔侧在线监测设备长距离、大功率、高效率、宽频带的无线供电。在此基础上建立系统级仿真模型,对U型无线供电系统的距离特性、频率特性、负载特性及电磁分布特性进行分析,验证了设计方案的可行性和电磁兼容性。最后搭建实验平台,在600 kHz的工作频率和1.2 m的传输距离下,系统输出功率达到73.58 W,能够满足杆塔侧在线监测设备的实际功率需求,为无线电能传输技术在高压设备供电领域的应用提供了参考依据。

极端气象条件下基于深度学习网络特征的变压器故障预测

根据极端气象条件下变压器产生故障时的环境参数,结合变压器故障预测中常用的油中溶解气体的含量,提出一种基于深度学习网络的故障预测方法。针对已有的变压器故障诊断方法泛化能力弱、时效性低、精度低等缺点,引入极端气象参数,并通过对多组数据序列进行时因分析,提取数据随着时间的变化关系;其次,设计一种新型的神经网络,将油气参数与极端气象参数的时间特征融合,并通过深度学习网络进行故障分类与预测。仿真实验结果表明,相比于其他传统故障预测方法,所提出的极端气象条件下基于深度学习网络的变压器故障预测方法准确率有显著提高。

特高压阀侧套管数字孪生系统集成设计方法

提出了一种数字孪生系统的集成设计方法,以满足真实工况下的实际应用。首先,分析了阀侧套管数字孪生系统的功能需求并构建了数字孪生系统框架结构;其次,基于系统框架结构的功能模块设计研发了对应的实现方法;最后,用一起阀侧套管数字孪生系统的应用对该方法进行了展示和验证。所提方法为数字孪生系统的实际应用提供了一种设计思路,可以为电网的数字化转型提供实用而有效的解决方案。

基于区块链数据安全机制的输变电工程建设动态计算技术研究

针对现今输变电工程施工过程中不确定性因素较多、造价计算偏向静态等问题,文章建立了基于区块链数据安全机制的输变电工程造价实时动态计算模型,实现了造价实时动态计算技术与计算结果的精准高效。文章以区块链可信数据交换技术为底层模型,利用区块链去中心化信任体系、链上数据不可篡改等特性,构建输变电工程的数据上传、交互、储存与计算的架构体系;使用粒子群算法优化径向基神经网络参数,构造输变电工程造价数据预测计算模型;采用杰卡德距离对计算结果进行校正,且在反馈误差的同时进一步优化计算模型。利用仿真算例验证了模型的先进性与可行性。

新能源发电设备接入的电磁暂态仿真研究

构建由风力机模型、双馈感应电机模型及传动系统等构成的双馈风力发电机组(DFIG)为新能源发电设备代表,进行考虑新能源发电设备接入的电磁暂态仿真研究,深度剖析DFIG接入后的电网系统平稳运行以及电压跌落状态下的电磁暂态响应。

基于暂态特征参数的数字式非接触负载测量研究

无线能量传输系统暂态过程中的高阶非线性问题是负载测量和辨识的一个难点,在处理由于高阶非线性出现的拍频信号时,现有模拟包络检波方法存在信号易失真、电路灵活性差以及测量范围有限等问题。针对此,提出基于希尔伯特变换的数字包络检波方法。在希尔伯特变换的基础上,设计数字包络检波器,提取电压拍频信号的包络线,并通过仿真和实验对所提方法进行验证,结果表明:对于不同待测负载,该方法均能够准确提取电压拍频包络线,实现负载阻值1~2000Ω范围内误差小于5%的测量。该方法拓宽了基于暂态特征参数的非接触负载测量的范围,为无人机等飞行器电池内阻的测量提供了新思路。

知识图谱在输变电设备运维中的应用

对输变电设备海量数据进行有效利用和管理是新型电力系统信息化发展的重要方向,挖掘电网输变电设备运维数据,并感知其运行态势,可保障输变电设备安全稳定的运行。该文将知识图谱引入输变电设备运维领域,分析输变电设备运维的数据情况和现存问题;介绍输变电设备数据融合聚类技术和运维知识图谱的构建技术;结合输变电设备运维特性,总结知识图谱在输变电设备运维中的典型应用场景;分析当前研究热点,探讨知识图谱在输变电设备运维领域的关键问题,并展望该领域的发展前景。运用知识图谱,在提高企业维修效率的同时,还能降低人力成本。

基于AHP-熵权法的输变电工程低碳评价体系及方案优选

“双碳”目标要求下,输变电工程项目向节能减碳方向发展势在必行。为掌握输变电工程减碳与成本及效益之间的本征关系,建立输变电工程成本效益评价指标体系。运用层次分析法(analytic hierarchy process,AHP)确定各项指标对成本及效益的影响权重,再采用熵权法对指标权重进行标准化及客观化修正,之后对每种技术方案选取1000个采样点进行敏感性分析,从而建立起较为完善的输变电工程综合评价体系。基于所建立的指标体系与数学模型对110 kV和220 kV案例进行分析,所得准则层与指标层误差均不足10%。随后提出8种备选减碳方案,逐一计算该8种方案全生命周期净现值与现金流,并对方案综合评分。最终得出结论:准则层中权重占比最高的为“新型变压器”技术,指标层中权重占比最高的为“变压器负载损耗”,且依据方案7改造有望以较低成本实现较高效益。

直流偏磁对500 kV变压器振动特性的影响分析

特高压直流工程单极-大地回路运行时,直流电流侵入大型变压器绕组,致使变压器振动加剧。为了深入了解直流偏磁对大型变压器振动特性的影响,分析了变压器的振动机理及直流偏磁的影响机制。在白鹤滩—江苏±800 kV特高压直流输电工程调试期间,对500 kV三相变压器的中性点电流、振动信号进行了实测,量化了直流偏磁程度,分析了不同直流偏磁程度下变压器振动信号时域及频谱特征。提取了波形畸变比、奇偶次谐波能量比、累计能量占比、功率谱熵等特征量来分析直流偏磁对大型变压器振动特性的影响。结果表明:直流偏磁导致波形畸变,1个工频周期内2个半周期对应的振动波形不再对称分布;随着直流偏磁程度增加,振动信号主频分量改变,50 Hz倍频谐波分量增多,其中50 Hz奇次谐波增幅要大于偶次谐波,且影响主要集中在600 Hz以内;由于铁心饱和作用,直流偏磁增大到一定程度时,磁不平衡性降低,振动信号复杂度不再增加。