Three-defense Line Coordination Strategy of the Guizhou Power Grid with the New Security Situation

In order to meet the requirements of Decree of the State Council of the People's Republic of China (No.599), this paper presents a three-defense line coordination strategy based on the Decree of the State Council (No.599). Taking the Guizhou power grid of 220 kV&500 kV as an example, the security and stability problem of the Guizhou power grid is analyzed. The strategy using three-defense line coordination for lowering the level of electricity safety accidents is researched. The analysis results show that the proposed coordination strategy is feasible, which can lower the level of electricity safety accidents under the same fault in same operation mode. Through studying the three-defense line of the Guizhou power grid, this paper presents a basic idea of the three-defense line coordination strategy based on the Decree of the State Council (No.599). The three-defense line coordination strategy provides reference for other provinces power grid.

Next Generation Narrowband(Under 500 kHz) Power Line Communications(PLC) Standards

In the past decade,several efforts around the world were started with the goal of introducing "smart metering" capabilities into the power grid.These efforts have spurred renewed interest in the design of next generation Narrowband Power Line Communications(NB-PLC) transceivers.In the past few years,ITU-T and IEEE have standardized a family of next generation OFDM-based NB-PLC transceivers some of which are today being considered for massive deployments in Europe and Asia.This paper addresses the important role that PLC has not only for smart metering but also for many other Smart Grid applications,and also gives an overview of the main differences between these next generation NB-PLC standards.

Regulating cost for renewable energy integration in power grids

To address the issue of climate change caused by the use of polluting, non-renewable energy sources, the use of renewable energy has gained momentum worldwide. Consequently, the increased integration of renewable energy sources into power grids has necessitated the inclusion of flexible capacities in the power systems to solve problems of intermittent and fluctuating characteristics associated with renewable generation outputs. In this work, we study the regulating cost of a power system with high renewable penetration using an improved time-series system production simulation analysis method. The operational cost of the system is considered as the objective function. Three different methods to increase regulating capacities, including using interconnection lines, building additional flexible power capacities, and retrofitting existing thermal power plants, are adopted and simulated to compare the costs of accommodating renewable energy in the system in these cases. Our results indicate that increasing the flexibility of thermal power plants and developing crossregional connection lines are cost-effective methods of increasing renewable energy consumption.

Implementation of Dynamic Line Rating in a Sub-Transmission System for Wind Power Integration

Based on conventional static line rating method, the actual current carrying capability of overhead conductors cannot be judged. Due to continuous increment in electricity demand and the difficulties associated with new line constructions, the overhead lines are therefore required to be rated based on a method that should establish their real-time capability in terms of electricity transmission. The method used to determine the real-time ampacity of overhead conductors not only can enhance their transmission capacity but can also help in allowing excessive renewable generation in the electricity network. In this research work, the issues related to analyzing an impact of wind power on periodical loading of overhead line as well as finding its static and dynamic ampacities with line current are investigated in detail. Moreover, the investigation related to finding a suitable location for the construction of a 60 MW wind farm is taken on board. Thereafter, the wind park is integrated with a regional grid, owned by Fortum Distribution AB. In addition to that, the electricity generated from the wind park is also calculated in this project. Later on, the work is devoted to finding the static and dynamic line ratings for “VL3” overhead conductor by using IEEE-738-2006 standard. Furthermore, the project also deals with finding the line current and making its comparison with maximum capacity of overhead conductor (VL3) for loading it in such a way that no any violation of safe ground clearance requirements is observed at all. Besides, the line current, knowing the conductor temperature when it transmits the required electricity in the presence of wind power generation is also an important factor to be taken into consideration. Therefore, based on real-time ambient conditions with actual line loading and with the help of IEEE-738-2006 standard, the conductor temperature is also calculated in this project. At the end, an economic analysis is performed to evaluate the financial advantages related to applying the dynamic line ratings approach in place of traditional static line ratings technique across an overhead conductor (VL3) and to know how much beneficial it is to temporarily postpone the rebuilding and/or construction of a new transmission line. Furthermore, an economic analysis related to wind power system is taken into consideration as well to get familiar with the costs related to building and connecting a 60 MW wind farm with the regional grid.

A Liability Division Method for Harmonic Pollution Based on Line-Transferred Power Components

The existing liability division methods for harmonic pollution are either inexplicit or incomplete in physical meaning. To compensate these defects, two new methods are proposed based on line-transferred power components in this paper. At first, all harmonic sources are represented by ideal equivalent current source, line current components and bus voltage components of a source are determined by stimulation of this source with all other sources disabled. Then, the line-trans- ferred power component owing to a source under all sources action together is determined by the theory of line-transferred power components, and called source’s line-transferred power component. At last, the liability of a source for line-end harmonic pollution is divided by two methods: the ration of the source’s line-transferred active power component to the total line-transferred power, and the ration of projection of the source’s line-transferred complex power component to absolute value of the total line-transferred complex power. These two methods are taken into account not only harmonic voltage but also harmonic current in the liability division. Simulation results show that the proposed liability division method based on active power component is the most effective and ideal one.

Broadband over Power Line (BPL): An Emerging Technology for Bangladesh

Broadband over Power Line (BPL) is an alternative means of providing high-speed Internet access, Voice over Internet Protocol (VoIP), and other broadband services to homes and businesses by using the existing medium voltage (MV) and low voltage (LV) power lines. This paper provides a comprehensive understanding about BPL with its implementation prospects. In this context, the existing power grid infrastructures are discussed elaborately. BPL system functionality with its components and its benefits over other access technologies is also pointed out. Implementation scenarios for various deployment options are illustrated here. The different implementation challenges for BPL system, such as the characteristics of power lines, attenuation problem, noise, potential interference with the other radio frequencies are also presented with their remedies. Comparative analysis between several broadband access technologies shows the feasibility of BPL deployments all over the world.

基于限流电抗器两侧特定频段暂态能量比的MTDC电网单端量保护方案

柔性直流输电技术有利于未来大量分布式能源接入电网,而配置快速、可靠的保护方案是柔性直流技术发展的关键。基于直流电网等效模型,提出一种基于限流电抗器两侧电压特定频段暂态能量比差异性的单端量故障区域识别方法。该方法依据贝瑞隆等效模型计算出限流电抗器两侧电压比,通过广义S变换提取限流电抗器两侧特定频段电压,根据故障时正负极限流电抗器的电压幅值差的差异性实现故障选极。最后在PSCAD/EMTDC平台搭建仿真模型,分析出发生区内外故障时差异性明显,具备较强的耐过渡电阻与抗噪声干扰能力。

更好的场所--政府建筑师的角色转变及其在悉尼货运线更新中的呈现

铁路遗产具有线性、综合性和辐射性的特征,对城市更新影响深远。在澳大利亚铁路遗产更新中,政府建筑师扮演了重要角色。澳大利亚政府建筑师曾负责设计重要公共建筑,这些建筑多为政府持有产权的城市地标。自2016年起,政府建筑师的职责重心从建筑设计转向设计管理。文章以政府建筑师的角色转变为线索,分析了悉尼货运线更新中的建筑设计和设计管理环节,更新内容涵盖欧缇莫动力博物馆、公共空间和地方级“绿网”三个层面。其中,政府建筑师通过制定设计政策和政策框架,持续地推广优秀案例、推动优质设计。这不仅为城市公共空间复兴提供了借鉴,也为拓展建筑师的职业范畴带来新思路。

多直流馈入受端电网的最大受电能力估计方法

为保证多直流馈入受端电网稳定运行,提出一种静态稳定约束下多直流馈入受端电网的最大受电能力估计方法。首先,基于奇异值理论推导出多直流馈入受端电网静态电压稳定约束;然后,在考虑静态电压稳定性约束的情况下,建立多直流馈入受端电网优化调度模型;接着,给出一种计及静态电压稳定约束的优化调度模型分段线性求解方法,并基于该方法给出最大受电能力估计方法;最后,通过修改的IEEE39节点系统验证本文所提方法的有效性。

基于改进下垂的多逆变器并联控制策略

针对微电网孤岛运行时,传统解耦式下垂控制策略由于未能考虑线路阻抗的影响,多逆变器并联运行时存在无功功率分配不均、环流等问题,论文提出一种基于自适应电压补偿的改进下垂控制策略。文中首先针对因线路阻抗不同所带来的电压跌落问题,增加了线路压降补偿环节,在此基础上,考虑逆变器出口处电压与母线电压的一致性,改进了下垂控制式,并利用低带宽通信技术获取各逆变器输出功率信息,引入自适应电压补偿环节,提高了逆变器间无功功率的均分精度。最后,基于Matlab平台搭建文章所提控制策略的仿真模型,仿真结果验证了所提控制策略的正确性与有效性。

电力网技术线损及降损对策解析

新时期,社会生产、生活对电能需求量不断增加,电力网损耗问题也愈加明显,这也让供电企业进一步提升了对节能降损问题的关注度。线损率会直接影响供电企业经济效益,也有效反映了供电企业管理水平,因此做好线损管理、采取有效降损措施有着重要意义。但目前部分地区普遍存在高线损情况,如何有效降低电力网线损一直都是电力企业管理的重点与难点。基于此,分析了电力网线损的概念与构成,从电力网结构、经济运行、电力设备等方面探究造成电力网技术线损的原因,并有针对性地提出几点降损对策,旨在降低电力网的线损量,提升供电企业的经营管理效益。

一种基于RPA技术的电网线路故障检测方法

由于电网电力故障检测具有重复性、高精度、低价值特征,线路故障数据的人工检测效率极低。为此利用RPA思维设计电网线路故障数据检测方法。在故障判断流程中引入三阶段RPA重复判断方法,通过构建检测矩阵和时间矩阵,计算故障初始行波波头到达端点的时间确定故障区域。在故障区域内找出一条疑似故障线路,并结合所定义的一条虚拟母线,通过反复计算验证找出准确故障线路。实验结果表明,所提方法故障检测的绝对误差小,错误故障检测率和遗漏故障检测率较低,故障数据检测的查全率与查准率较高,实际应用效果好。

电网架空输电线路绝缘子缺陷识别算法研究

电网架空输电线路绝缘子长期处于外部暴露环境中,易产生侵蚀、开裂、破碎等问题,导致电网运行的可靠性降低。为此,对电网架空输电线路绝缘子缺陷识别算法进行了研究。通过滤波去除采集的绝缘子图像乘性噪声,利用不同尺度高斯掩膜进行卷积处理,并结合图像梯度方向提取表面缺陷特征。将构建的深度前馈神经网络作为基本架构,设置三层网络结构的自编码器。在前馈网络的优化目标函数中融入惩罚因子,以构建稀疏性限制条件。通过遗传算法优化自编码器初始权值,经网络迭代得到表面缺陷识别结果。试验结果表明,所提算法对绝缘子缺陷的识别准确率始终高于90%、平均识别用时为1.72 s,具有显著的可行性。该研究对监控安防、图像分析等领域具有一定的启示意义。

基于无人机的架空输电线路缺陷智能识别

为了提高智能识别效果,设计一种基于无人机的架空输电线路缺陷智能识别方法。建立图像信息提取模型,在图像信息卷积输出结构中获取卷积核的输入输出值以及激活函数,得到函数的回归损失函数值。生成架空输电线路缺陷判别网络,得到不同采样点的目标函数,建立离散微分算子的矩阵信息,计算双边拟合误差,匹配特征点的函数值。设计线路缺陷智能识别算法,完成架空输电线路缺陷的智能识别方法设计。实验结果证明,设计方法可以以最少的训练次数获取最小的损失值,得到损失值的最小值约为0.35,识别效果更佳,具有一定应用价值。

基于多阶段协同的电网厂站接线图智能识别

电网厂站接线图作为电力系统网络结构的重要数据,承载着电力设备运行的关键信息,在电网调度控制应用中具有重要作用。针对调度运维人员手动绘制方式导致工作繁琐、任务量大的问题,提出基于多阶段协同的电网厂站接线图智能识别方法,实现机器代人绘图。首先,采用切割检测增强对图元小目标的检测能力,通过形态特征提取及模糊比对处理实现图元方向识别;其次,基于随机粘贴原理增强文字识别模型的鲁棒性,基于知识融合技术提升图元文本匹配准确性;最后,基于连通域检测识别连接线,采用遍历筛选匹配图元与主接线的连接关系。实验结果表明,该方法对电网厂站接线图整体识别准确率在88%以上,将其应用变电站监控系统、换流站运行人员控制系统中,极大提升了作业人员构图建模效率。

煤矿电网的单相接地故障选线研究

为解决采用谐振接地系统的煤矿电网在发生单相接地故障后难以正确选择故障线路的问题,提出了一种基于故障后暂态信息和聚类分析的故障选线方法。首先计算故障后各线路暂态零序电流的12种时域特征和5种频域特征来得到故障特征向量,接着将各线路故障特征向量进行归一化处理并添加辅助向量,最后通过聚类分析筛选出故障线路。该方法实现简单,适用性强,可以正确识别母线故障。仿真分析结果验证了该方法的有效性。

山区电网线路过载保护协调优化控制策略研究

山区电网小水电众多但负荷轻,若叠加新能源大量接入,将造成夏季丰水期输电断面过载,限制清洁能源外送和威胁电网设备安全。为此,提出将断面过载保护与可调节电源进行协调配合以获得最优控制效果的保护动作策略。首先,基于潮流追踪法确定电源至断面的功率传输路径,并基于功率灵敏度确定单个电源对过载线路的影响大小;然后,建立以系统电源损失出力最小和保护动作后系统安全裕度最大为目标的多目标优化模型,通过优化电源出力和保护动作量实现电源出力损失最小和系统安全裕度最大,减少因源荷波动造成保护频繁动作;最后,以某一山区电网为算例进行仿真验证,计算结果表明所建立的模型能够实现电源出力损失最小和系统安全裕度最大的目标。

智能电网中的线损管理技术分析

阐述针对电网线损管理中的问题,包括审核管理不严、线路设备老化、监督管理不到位,从构建完善的审核机制、完善智能化线损管理方案、构建完善的降损节能管理机制方面提出应用对策。

市县级电网线损管理水平对标评价方法研究

为解决当前地区线损管理考评方式仅关注线损率指标的高低,而难以全面地评价电网企业线损管理能力优劣的问题,文章提出了一种市县级电网线损管理水平对标评价方法。首先,基于地区客观特征,应用聚类分析方法,对市县级对标群组进行科学划分;其次从电网结构、设备属性等5个维度,构建电网线损影响因素评价指标体系;最后,基于灰色关联分析计算地区线损综合评分,通过比较综合评分排名与电网实际线损率排名的差距,实现对同类地区电网线损管理水平的对标评价。

基于云计算的农电网低压电力线载波通信抄表系统设计

文章设计并实现了一种基于云计算的农电网低压电力线载波通信抄表系统。该系统应用最新的载波通信技术和云计算资源,全面覆盖了从抄表系统需求分析、载波通信模块设计,到抄表数据的编码与传输,再到系统界面与交互设计的每一个环节。同时,通过系统化的测试证实该系统具有较好的性能和实用性,为农电网的智能化管理提供有效的技术支持和实现路径。