面向最小配电块的配网可靠性通用矩阵评估算法

笔者采用面向最小配电区域的等值网络模型,使计算元件数极大简化;提出了基于分区模型的网络描述矩阵,能迅速方便地划分出各类故障节点集;最后归纳总结出网络可靠性指标的通用矩阵评估公式。该算法考虑了负荷熔断器和馈线断路器的不可靠开断、多备用电源的分布,通过网络描述矩阵建立的可靠性评估矩阵公式具有较强的通用性,将配电线路架空部分和电缆部分参数分开设置,更加贴近应用实际。算例验证了该算法的可行性和高效性。     

Reliability of lightning-resistant overhead lines

Lightning continues to be the major cause of outages on overhead power distribution lines. Through laboratory testing and field observations and measurements, the properties of a lightning stroke and its effects on electrical distribution system components are fairly well-understood phenomena. A meticulous compilation of 32 years of historical records has been kept for outage causes, duration, and locations for eight distribution feeders at the Oak Ridge National Laboratory (ORNL). Due to the limited growth of ORNL, the number, length, and location of the 13.8 kV overhead lines have remained the same between 1960 and 1992. Except for noted differences (voltage construction class, length, age, and maximum elevation above a reference level), other factors that could influence the reliability of an overhead line have remained nearly the same. This allowed a meaningful reliability study to be performed on the entire ORNL electrical distribution system. In this article, the main findings of the reliability assessment as it relates to lightning-resistant overhead line construction techniques are out-lined, and a simple and cost-effective method to reduce lightning caused outages is offered. In addition, comparisons are made between the failure rates and causes experienced at ORNL and those in industry surveys. Where large discrepancies exist between survey data and experiences at ORNL, evidence is presented to explain the differences between ORNL's distribution system and those typical of industry     

基于级联全桥型直流断路器的直流配电网自适应重合闸方案

柔性直流配电网是配电系统的重要发展方向,可以采用电缆和架空线2种方式组网。鉴于架空线路瞬时性故障多发的特点,基于架空线的柔性直流配电网应配备有效的自适应重合闸方案,以提高供电可靠性。为实现这一目标,从断路器线路端电压与电流的相位差异特征出发,提出一种基于级联全桥型直流断路器控制的自适应重合闸方案。首先,通过断路器转移支路的主动控制产生一定频率的故障检测电压;进而,根据断路器线路端电压电流在对应频率下相位特征的差异,区分瞬时性和永久性故障,并进一步分析了过渡电阻等因素的影响;最后,利用PSCAD/EMTDC仿真平台搭建了柔性直流配电网模型,验证了所提自适应重合闸方案的可行性和有效性。     

A value-based probabilistic approach to designing urban distribution systems

Achieving high distribution reliability levels and concurrently minimizing capital costs can be viewed as a problem of optimization. Assuming given outage rates and repair times, distribution system design is the remaining factor in determining customer reliability. Including customer value of reliability in an economic analysis allows for optimization of the major components of distribution system design. Using mathematical models and simulations, a comparison of design concepts can be performed to compute the optimal feeder section length, feeder loading level, and distribution substation transformer loading level. The number of feeder ties and feeder tie placement are also optimized through the models. The overall outcome of this analysis is that capital costs can then be directed towards system improvements that will be most cost-effective in improving system reliability. This paper presents a value-based probabilistic approach to designing urban distribution systems. The value-based reliability methodology is illustrated using a practical urban distribution system of MidAmerican Energy Company.     

配电网架空线路无人机自主巡检技术分析

为提高雄安新区配电网架空线路运行可靠性,研究了无人机自主巡检技术,开发了配电网架空线路无人机智能巡检平台.针对水区、工地、农田等巡视人员难以到达的区域开展无人机自主巡检,采用基于关键坐标点的路径规划算法对配电网线路进行规划,保证无人机自主巡检的精确性.通过搭载高清摄像头、红外热像仪等提升无人机巡检感知能力,可及时发现异...     

电力系统架空多导体传输线的高频耦合电流计算模型

架空传输线作为电力系统中的重要组成部分,其在瞬态电磁场或激励源作用下（例如高空电磁脉冲）通常能够耦合出高幅值过电流,将作为强电磁干扰的耦合路径对电力系统造成严重干扰。现有建模方法中,经典传输线理论在处理非电小尺寸横截面线路的高频耦合问题时存在较大误差;全波数值算法（例如矩量法）依赖于网格剖分的计算过程使得其在处理长线情况时存在效率问题。此外,电力系统中往往线缆数量通常较多,且地面均考虑为实际有耗情况。为解决上述问题,本文提出了一种能够计算电力系统架空传输线高频耦合电流的渐近模型。基于计算效率较高的渐近理论,引入反射与散射过程对高阶模式分量进行量化,并针对任意线路数量、任意参数地面及不同激励情况,推导了其统一的电流表达式。最后利用全波数值仿真以及天线辐照实验验证了模型的有效性和可靠性。本文计算模型能够快速计算高频耦合电流,为线路防护以及电磁效应研究提供理论基础与数据支撑。     

配电系统综合自动化的研究与设计

针对目前我国的配电网绝大多数为树状结构的架空线可靠性差、送电距离过长、损耗严重、电压质量差的问题,提出了断路器优化定位的数学模型,并应用遗传算法解决非线性优化问题,构造了遗传算法所需要的适应度函数。对基于CAN总线通信方式的配电自动化进行了系统研究,设计了配电自动化系统的整体方案,包括系统设计、功能设计、软件设计和硬件配置等。     

基于馈线元计及负荷分级的含DG配电系统可靠性分析

为实现配网可靠性快速评估,在深刻理解经典解析法的基础上,按系统主馈线上的开关元器件进行切割划分,将分段开关或断路器视为切割边界形成馈线元,再以馈线元为单位且考虑负荷转移问题进行配网可靠性分析;并通过评估结果,按负荷重要度分级以经济效益最大化将相应馈线元加入分布式电源(DG)进行改造,以此增强配电系统内重点电力用户供电可靠性,降低网内负荷持续停电经济损失。以RBTS-BUS 6系统进行算例分析,算例结果验证了本文提出方法的有效性。     

Analysis of Animal-Related Outages in Overhead Distribution Systems With Wavelet Decomposition and Immune Systems-Based Neural Networks

Outages in overhead distribution systems caused by different factors significantly impact their reliability. Since animals cause large number of outages in overhead distribution systems, analysis of these outages has a practical value as it allows utilities to keep track of historical trends. This paper presents a methodology for yearend analysis of animal-caused outages in the past year. Models to estimate weekly animal-caused outages in overhead distribution systems using combination of wavelet transform techniques and neural networks are presented. Discrete wavelet transform is applied to decompose the time series of weekly animal-caused outages into two components and separate neural networks are constructed for each decomposed coefficient series. The outputs of neural networks are combined according to wavelet reconstruction techniques to get estimated results for the weekly animal-caused outages. Artificial immune system (AIS) is used to overcome the overtraining problem associated with neural networks. Results obtained for four districts in Kansas of different sizes are compared with observed outages to evaluate performance of three different models for estimating these outages.     

Modeling Weather-Related Failures of Overhead Distribution Lines

Weather is one of the major factors affecting the reliability of power distribution systems. An effective method to model weather's impact on overhead distribution lines' failure rates will enable utilities to compare their systems' reliabilities under different weather conditions. This will allow them to make the right decisions to obtain the best operation and maintenance plan to reduce impacts of weather on reliabilities. Two methods to model overhead distribution lines' failure rates are presented in this paper. The first is based on a Poisson regression model, and it captures the counting nature of failure events on overhead distribution lines. The second is a Bayesian network model, which uses conditional probabilities of failures given different weather states. Both methods are used to predict the yearly weather-related failure events on overhead lines. This is followed by a Monte Carlo analysis to determine prediction bounds. The results obtained by these models are compared to evaluate their salient features     

配电自动化终端布点优化的动态规划研究

提高配电系统的供电可靠性是配电自动化系统建设的重要目标,但需考虑配电自动化设备的经济成本,且实际工程中通常是分阶段拨款。提出一种考虑供电可靠性和经济成本的配电自动化终端布点优化的动态规划方法,混合使用多种类型配电终端,在架空线安装故障指示器、电压时间型终端、电压电流型终端,在电缆线安装故障指示器、二遥终端和三遥终端,根据自动化终端类型确定故障影响模式。运用JAVA语言进行编程,实现从XML文件读取配网数据。以开关为边界划分配电网的区域节点,采用开源的图形库JGraphT存储配网拓扑信息。考虑故障停电情况,以用户年平均故障停电时间为评价供电可靠性的指标,分别建立以可靠性指标为优化目标和以投资总额为优化目标的配电自动化终端布点优化的动态规划模型。使用建模系统GAMS求解模型,得到配电终端布点优化结果。采用某地区区域配电网自动化终端布点规划作为算例验证,结果显示了该方法的可行性与优越性,为类似实际工程提供借鉴与依据。     

Fuse cutout allocation in radial distribution system considering the effect of hidden failures

Among the several components of distribution systems, protection devices present a fundamental importance, since they aim at keeping the physical integrity not only of the system equipment, but also of the electricians team and the population in general. One of the protective devices playing a vital role in overhead distribution lines is fused cutout. At the era of privatized utilities, the protection devices should be allocated and coordinated optimally to reduce capital investments and the system outage costs. Amid this situation, the mentioned type of the protection device (fuse cutout) has not been studied for economical allocation up to now. In this paper, responding to this need, an accurate reliability model of fuse cutout containing hidden failures is figured out in the shape of a new Markov model. This model is used for economical allocation of the fuse cutouts. On the basis of the proposed model, a methodology for economic allocation of fuse cutouts is presented. This methodology involves the worth of energy not supplied (ENS) of the network and makes a balance between the cost of fuse cutout installation and the benefit of ENS decrease because of the minimizing the faulty zone by using more fuse cutouts. The methodology is tested on a sample distribution network as well as on IEEE 6-bus distribution test system (RBTS). Moreover, its capability on decision making about the fuse cutout placement and its simplicity for implementing on MV overhead lines are displayed.     

基于阻抗源变换器的光伏直流升压汇集系统

针对大型光伏电站直流升压汇集技术挑战,提出一种计及阻抗网络概念的新型光伏直流升压汇集系统解决方案。该方案以一种阻抗型多模块串联式直流升压变换器为核心,具备多路最大功率点跟踪(MPPT)与高增益升压变流一体化功能,从而无需低压直流母线与专用MPPT装置,结构清晰可靠,便于内部故障隔离与整站动态控制。阻抗网络的引入,一方面具备灵活调压能力,可有效地解决输入光伏阵列间功率不均衡问题,具备良好运行适应性;另一方面具备抵御直通短路故障能力,可以大幅度提升电力电子系统运行可靠性。详述了系统架构、核心直流升压变流器拓扑、工作原理与控制方法。针对光伏阵列输出功率均衡与不均衡两种典型工况,对该系统进行仿真验证。仿真结果表明所述理论分析正确可靠,该系统对于未来直流光伏电站的推广应用具备潜在应用价值。     

Covering all the bases - industrial power system design in a utility environment

The scheme discussed here is unique: a large electrical network is spread over a very large geographic area. This creates an exceptional set of circumstances. Construction specifications and techniques are used that increase the reliability of the system above standard utility practices. This adds to the cost of the project, and necessitates modified approaches to overhead line construction. Transformer selection and design is greatly influenced by the size of the load, as well as overhead pole construction. PF correction is accomplished using both standard distribution level capacitors, and using medium-voltage capacitors at the voltage terminals. Lightning protection uses both standard surge arrestors on the line, as well as advanced grounding systems. In each of these cases, standard utility construction techniques are combined with industrial design to meet the requirements of the system. Without the use of computer-based system modeling, proper design and operation of such a complex system would be impossible. Computer models give an accurate picture of the loading on the system in a particular configuration. They also aid the engineer in selection and coordination of protective devices, as well as power-factor correction. Conclusively, with the aid of modern tools, a system can be constructed that serves the needs of an industrial user in a utility environment.     

基于成功流法的配电信息物理系统可靠性评估

文章引入成功流法解决现有蒙特卡洛法应用于大规模配电信息系统可靠性评估耗时的问题。根据智能分布式的故障处理模式对信息物理系统进行设备及功能可靠性建模，利用同一系统内、不同系统间元件之间的依存关系定量分析信息系统故障对物理系统供电可靠性的影响，获得计及信息系统影响的成功运行频率概率和区域成功运行时间概率，并由此得到负荷点及系统可靠性指标。最后，将文章提出的方法与蒙特卡洛法进行比较，计算结果表明文章提出的方法具有较好的精度及实用性，在大规模配电信息物理系统中效率优势更为明显。     

基于可靠性跟踪的薄弱环节辨识方法及在省级电网可靠性改善中的应用

可靠性跟踪就是运用跟踪思想确定电网各节点或系统可靠性指标在元件间的分配关系,即确定元件对节点或系统可靠性指标的"贡献"比例,进而对比不同元件对系统不可靠性的贡献大小,辨识电网的薄弱环节。文中运用可靠性跟踪原理,分析了某省电网各元件对系统不可靠性的分摊关系,辨识出四种典型运行方式下系统的薄弱环节,并提出了针对性的两种电网改善方案,通过对改善方案的改善效果进行后评估,验证了基于可靠性跟踪的省级电网薄弱环节辨识方法的正确性和所提出改善措施的合理性。     

城市中压配电网典型接线方式分析

配电网改造和配电网自动化系统建设的目的在于提高系统的可靠性,配电网接线方式的选择是提高配电系统可靠性的前提和重要基础。首先,介绍了配电网接线方式的选择原则,接着从经济性、可靠性、灵活性等方面对城市中压配电网络的常用接线方式进行了分析比较,如架空线路接线方式、电缆线路接线方式、架空线路和电缆线路混合接线方式,根据不同情况推荐了适用的电网接线方式。     

基于开关影响范围的复杂配电网可靠性顺流评估算法

以开关为对象,提出了复杂中压配电网可靠性顺流评估算法。该算法根据原始数据形成开关对作用元件、节点和开关对之间的父子关系矩阵,以开关对的作用元件组为单位进行可靠性分析,避免了复杂的故障搜索,根据开关对之间的父子关系矩阵可快速确定节点的故障类型,形成系统和节点的可靠性指标。RBTS-bus6系统和实际中压配电系统的仿真计算结果表明了该算法的正确性、高效性和实用性。     

复杂配电网络可靠性评估的向量法

在故障模式后果分析法的基础上，提出配电网络可靠性指标计算的向量法。该方法以构造负荷点供电“最小路馈线段行向量”的方法，方便地求得带子馈线、备用电源的复杂配电网络的可靠性指标。在最小路馈线段行向量生成后，计算中不需要再考虑网络结构，可简化计算。同时，还有助于方便地找出配电网中的薄弱环节。实例计算表明，向量法计算结果准确、计算过程更加简单。     

基于小波AlexNet网络的配电网故障区段定位方法

文中提出一种基于深度网络迁移学习的配电网故障区段定位方法。利用小波包变换(WPT)分解配电网各区段的电量信号,将各节点小波包系数按照低频到高频的顺序重新排列获得时频矩阵,通过颜色编码将时频矩阵转成具有图像性质的像素矩阵,像素矩阵囊括了当前系统的工作状况信息,利用迁移学习AlexNet网络,调整网络结构使其适应于配电网故障区段辨识,通过微调的AlexNet网络自主挖掘像素矩阵的故障特征作为预测变量,利用门控循环单元(GRU)、学习向量量化(LVQ)、朴素贝叶斯分类器(NBC)、极限学习机(ELM)、支持向量机(SVM)等模式识别算法进行故障特征分类,从而实现配电网故障区段定位。针对多分支的线缆混合线路进行实验分析,比较5种模式识别算法的分类效果,得到GRU算法准确率可以达到99.92%,证明了该方法不受故障时刻、故障类型和过渡电阻等因素的影响,可满足配电网对故障区段定位准确度和可靠性的需求。