Electrical characteristics of new three-phase traction power supply system for rail transit

A novel three-phase traction power supply system is proposed to eliminate the adverse effects caused by electric phase separation in catenary and accomplish a unifying manner of traction power supply for rail transit.With the application of two-stage three-phase continuous power supply structure,the electrical characteristics exhibit new features differing from the existing traction system.In this work,the principle for voltage levels determining two-stage network is dissected in accordance with the requirements of traction network and electric locomotive.The equivalent model of three-phase traction system is built for deducing the formula of current distribution and voltage losses.Based on the chain network model of the traction network,a simulation model is established to analyze the electrical characteristics such as traction current distribution,voltage losses,system equivalent impedance,voltage distribution,voltage unbalance and regenerative energy utilization.In a few words,quite a lot traction current of about 99%is undertaken by long-section cable network.The proportion of system voltage losses is small attributed to the two-stage three-phase power supply structure,and the voltage unbal-ance caused by impedance asymmetry of traction network is less than 1‰.In addition,the utilization rate of regenerative energy for locomotive achieves a significant promotion of over 97%.

Research on the Recognition Method of Electric Energy Meter Lead Title based on the Fuzzy Image Processing

This article puts forward an automatic recognition algorithm of electric energy meter lead seals： firstly, the image will be histogram equalization, smoothing, binaryzation pretreatment, then according to the image characteristics of text changes, the system can quickly and accurately segment image from complex background, finally the system extract different dimension and the feature of English and Arabia using digital projection transform coefficient method and to identify the corresponding number by BP neural network, solves the problem of automatic recognition of electric energy meter lead sealing.

A new method of electric energy metering considering harmonic responsibility

Aiming at the shortcomings of the existing electric energy metering method,combining with the harmonic responsibility analysis model based on the reference impedance method and the idea of apparent power decomposition in IEEE Std 1459-2010 standard,two new metering indicators—billing active power and billing power factor are defined.A new electric energy metering method is proposed and its specific implementation steps are given.The simulation model is built in Matlab/Simulink,and three different examples are set up.Using the simulation data,the various metering indicators need to be examined by the existing electric energy metering method and the new electric energy metering method are calculated.The calculation results show that the new electric energy metering method not only overcomes the shortcomings of the existing electric energy metering method,but also is very easy to be popularized and applied.

A Novel Bidirectional Interaction Model and Electric Energy Measuring Scheme of EVs for V2G with Distorted Power Loads

With the increasing demand for petroleum resources and environmental issues,new energy electric vehicles are increasingly being used.However,the large number of electric vehicles connected to the grid has brought new challenges to the operation of the grid.Firstly,A novel bidirectional interaction model is established based on modulation theory with nonlinear loads.Then,the electric energy measuring scheme of EVs for V2G is derived under the conditions of distorted power loads.The scheme is composed of fundamental electric energy,fundamental-distorted electric energy,distorted-fundamental electric energy and distorted electric energy.And the characteristics of each electric energy are analyzed.Finally,the correctness of the model and energy measurement method is verified by three simulation cases:the impact signals,the fluctuating signals,and the harmonic signals.

Energy flow problem solution based on state estimation approaches and smart meter data

Accurate electric energy(EE)measurements and billing estimations in a power system necessitate the development of an energy flow distribution model.This paper summarizes the results of investigations on a new problem related to the determination of EE flow in a power system over time intervals ranging from minutes to years.The problem is referred to as the energy flow problem(EFP).Generally,the grid state and topology may fluctuate over time.An attempt to use instantaneous(not integral)power values obtained from telemetry to solve classical electrical engineering equations leads to significant modeling errors,particularly with topology changes.A promoted EFP model may be suitable in the presence of such topological and state changes.Herein,EE flows are determined using state estimation approaches based on direct EE measurement data in Watt-hours(Volt-ampere reactive-hours)provided by electricity meters.The EFP solution is essential for a broad set of applications,including meter data validation,zero unbalance EE billing,and nontechnical EE loss check.

光伏新能源电能信号游程域模态分解理论与特征提取

高比例光伏新能源接入下的电能信号呈现出强随机、快时变、大波动特性,常导致电能表电能计量严重超差,影响电能交易的公正合理性。针对新能源电能信号敏感特征不清楚、对电能表电能计量影响不明确的问题,建立了游程域映射理论,解决了电能信号在游程域的表征问题;提出了游程域模态分解(R-EMD)方法,基于游程完成电流幅度在长持续时间下局部区间的自适应模态分解,得出光伏新能源电能信号的2个全局重要特征;构建了游程域特征参量与特征函数,并提取得到光伏新能源电能信号的4个游程域敏感特征;通过实验验证了游程域敏感特征对电能计量的影响。

Effect of harmonic distortion on electric energy meters of different metrological principles

This paper deals with the errors of electric energy metering devices as a result of distortions in the shape of the curves of voltage and current load. It is shown and proved that the errors in energy measurements depend on the design and the algorithms used in electricity meters. There are three main types of metering devises having different principles: inductive (electro-mechanical), elec-tronic static, and digital electronic (microprocessor). Each of these types has its measuring features. Some devices take into account all the harmonic distortions and the constant component which occur in the network while others measure the power and energy values of the fundamental harmonic only. Such traits lead to the discrepancies in the readings of commercial electric energy meters of different types. Hence, the violations in the measurement system unity occur, and a significant error can be observed in the balance of transmitted/consumed electric energy.

对有关电能计量若干问题的思考

文中基于论证和较全面分析,就不同场景下电能计量所关注的截然不同的问题、更好利用大数据去构建电能表检验新方法、动态电能计量研究面临新挑战、关注超谐波电能计量、不宜将电能计量装置与电能表简单划等号,以及测量准确度不同于测量精度等六个问题,阐述了作者的观点和认识,旨在对开展相关研究,以及更清楚理解相关测量方法及概念等起到促进作用。

Design of PLC Centralized Meter Reading System

With the increasing development of urban housing construction and the rapid expansion of the number of inhabitants and independent electric energy meter, a variety of tariff systems are launched, meter reading metering becomes increasingly complex, and the traditional manual meter reading is already hard to adapt to new changes. This thesis studies the design of a centralized meter reading system. This program applies PLC technology for information transfer, which guarantees the stability of system carrier communication. This system is composed of electric energy meter, collector, concentrator and other hardware, as well as communication and management software of collection copies system. It is characterized by functions of power data collection, centralization, remote transmission, distance control, electricity analysis, line loss calculation, integrated query, and time-sharing billing. Its promotion and application will necessarily provide important technical means for power supply, property and urban utilities to improve their modernized and automatic management level.

Power ＂Smart Pricing＂ with and without Smart Meters

Over the past several years, the Taiwan Power Company has launched two smart pricing programs to assess the demand response of residential customers： the TOU （time-of-use） rate scheme and the DRI （demand reduction incentive） scheme. This paper discusses these two programs and evaluates their respective performances. We develop an efficient approach based on marginal cost pricing to redesign the TOU rate scheme. In our finding, the TOU price levels could be revised to encourage more customers to participate by enlarging the price gap. Moreover, the DRI scheme can be further improved in order to reach an efficient win-win solution among customers, the utility and society. This can be achieved via a careful design of incentive tariff discounts to take account of the time-of-use or location-specific features of the power supply/demand condition.

基于节能降耗的飞轮储能电力计量技术

飞轮储能电力计量技术,是一种将飞轮储能与电力计量技术相结合的创新型电力管理技术。飞轮储能以其高功率密度、长寿命、快速响应和环保无污染等特点,在电力系统中展现出巨大的应用潜力。而电力计量技术则是电力系统中的重要组成部分,用于准确计量和监测电能的使用情况。将两者结合,飞轮储能电力计量技术旨在提高电力系统的运行效率,优化资源配置,并推动电力行业的可持续发展。本文从节能降耗的角度出发,分析飞轮储能电力计量技术的应用研究情况,并从多个角度阐述未来飞轮储能电力计量技术的应用研究方向,以实现对电力系统的高效、绿色管理。

基于混合铁心的新型电流互感器研究

传统电流互感器铁心饱和会导致其二次电流波形发生畸变,进而可能影响电能计量的精度或引起继电保护设备错误动作,威胁电网的安全稳定运行。针对此类问题,提出了基于混合铁心的新型电流互感器(CCCT)。CCCT主要由混合铁心、二次绕组、二次电阻、磁场传感器与信号处理电路组成,其中混合铁心包含完整的内铁心与带气隙的外铁心,磁场传感器放置在外铁心的气隙中,其输出信号用于补偿发生畸变的二次电流。为验证该结构的有效性,进行了有限元仿真,制作了CCCT样机并进行了正弦交流电流、正弦半波电流、短路电流和直流电流的测量实验。有限元仿真与实验结果表明,CCCT在额定电流下的复合误差小于0.2%,稳态对称短路电流下的复合误差为2.04%,暂态短路电流下的峰值瞬时误差为4.25%,直流条件下输出与输入的拟合优度为0.999 9,既基本保留了传统电流互感器的测量精度,也具有良好的暂态响应特性与抗直流特性,可同时满足相关标准对测量、保护用电流互感器的精度要求,具备在实际工程中应用的潜力。

考虑电力市场化交易的电碳表计量及实现方法研究

电力间接碳排放是电力用户碳排放的主要来源之一,碳排放流是计算电力间接碳排放的重要方法。目前,基于碳排放流的计量理论尚未考虑电力市场化交易的影响,缺乏相应工程应用的实现方法,参与电力市场化交易的用户难以准确获得其用电量所对应的间接碳排放量。为解决这一难题,该文研究碳排放流理论的分布式电能实现方法,考虑电力市场化交易对交易双方及相关用户碳排放因子的影响,提出含电力市场化交易的电力系统源、网、荷全过程电碳排放量计量方法;并研究存在绿电交易、储能等情况下的电碳排放因子特点及计算方法。基于上述理论,研制了电碳表及其相关系统,并利用电碳表系统对某地电网部分实际拓扑进行分析,验证了所提方法的有效性及电碳表的实用性。

量子功率标准综述:原理、现状及展望

随着国际单位制(International System of Units,SI)量子化变革的稳步推进和广域落地实施,以更加准确、稳定的量子计量标准替代实物计量标准,已成为计量学领域的重点攻关任务之一。量子功率标准对电能的精准计量将发挥关键作用,可有力保障电能贸易结算、电碳交易的公平和公正。首先,该文从交流功率标准和直流功率标准两方面,对当前国内外功率标准研究现状进行了综述。对于交流功率标准,分别阐述了工频交流功率标准和宽频交流功率标准的基本架构、测量原理,指出基于热电变换器的交流功率标准可实现工频和宽频(百kHz)交流功率的高准确度溯源,而国内外已有交流量子功率标准的工作频带一般不超过400Hz,需开展宽频交流量子功率标准研究;对于直流功率标准,国内外还处于初步研究阶段,由于当前尚缺乏对直流电压、电流信号的标准化定义,导致应以何种形式的直流功率信号作为标准被测对象尚不明确,无法为构建直流量子功率标准提供方向性指导。随后,该文对比分析了不同的功率标准,给出了对当前构建功率标准所存在问题的思考,并试对交、直流功率标准的未来发展做出展望:随着宽频量子电压标准技术的发展与进步,有望实现宽频量子功率标准;同时,开展宽频、宽量限电压、电流放大器和比例技术的研究,是实现高准确度交、直流量子功率标准的重要前提。

基于云技术的电能表校验装置远程计量

通过应用数字化技术实现电能表校验装置的远程计量。该方法使用软件控制被测设备与标准表,利用云技术使计量技术机构实验室与客户实验室之间数据互通,保障数据的可靠性与安全性。该方法与传统电能表校验装置计量相比,创新服务方式、提高服务效率,为其他计量领域实现远程计量提供借鉴参考。

基于台区电能量分层级解耦的电能表远程在线校准

针对电能表元件稳定性较差的问题,提出基于台区电能量分层级解耦的电能表远程在线校准方法。根据台区电能量分层级精准解耦原则,设置典型分层端口结构,求解微分解耦数据方程,实现对电能系数的计量处理。分别从AD转换器量化误差、数值求积截断误差、同步误差三个角度着手,分析校准参量的取值结果,完成远程在线校准设计。实验结果表明:采用所提方法的总线电能表示数、支线电能表示数与理想示数之间的差值水平均能得到较好控制,与三轴同步校准方法相比,更符合维持电能表示数稳定性的实际应用需求。

基于季节性指数平滑法的电能表需求预测分析

随着智能电能表大规模普及应用,电能表需求数量日益庞大,采用经验人工估计容易造成电能表临时短缺和库存积压等问题。基于计量系统中的电能表历史安装数据,采用简单季节性模型、Winters加法模型和Winters乘法模型,并结合LSTM模型对结果进行对比分析,比较不同模型的优劣,确定电能表需求预测最优方法。实证结果表明:Winters乘法模型预测效果最好,预测值平均误差为2.46%,预测趋势符合实际情况。Winters乘法指数平滑法能够对电能表需求变化趋势进行科学合理预测,可以协助供电公司更加高效开展电能表运营管理,提高计量资产利用效率。

电能计量在线监测模型设计探索

为准确实时定位计量故障,保障电网安全运行,提升经济效益和社会效益。通过分析电能计量装置管理需求,设计电能计量在线监测设计方案,搭建以异常信息生成模块、消缺模块及专项分析模块为主体的电能计量装置在线监测模型。建立分钟级海量采集数据的计量异常实时研判体系,并分析异常消缺的历史数据,评价研判结果,促进规则模型持续优化。结果表明,异常研判更加及时准确,说明建立合理的模型,通过分析海量数据,现场反馈信息等,可以精确定位故障,满足电能计量装置在线监测的功能需求。

电磁兼容检测用电能表检验装置的研制

针对电能表电磁兼容检测过程中辅助设备导致的测量重复率较低问题,基于场理论和电路原理,研制出性能优异的电磁兼容检测用电能表检验装置。本文研究了电能表电磁抗扰度实验过程产生电磁干扰的传输路径,分析了电能表检验装置承受的传导和辐射电磁干扰特性;结合干扰耦合方式、干扰频段和干扰强度,优化了装置电源驱动能力、干扰去耦能力、外壳电磁屏蔽效能和内部线缆布局;并提出合理的试验方案,验证了受干扰时装置的性能。最后,制订了电力行业标准DL/T 2556.2-2022《电力行业电磁兼容检测辅助设备第2部分:电磁兼容检测用电能表检验装置》,总结了电磁兼容检测辅助设备的技术要求和验证方法。

基于数据挖掘的计量参数异常4步优化识别技术

针对传统计量数据异常识别方法会出现较大的识别偏差,影响计量数据的正常统计与分析。结合历史识别经验,引入数据挖掘算法对其进行针对性优化,通过电能计量数据采集聚类计算;基于数据挖掘的聚类数据贝叶斯分类;对计量参数的挖掘确定;异常数据识别;通过上述4步优化,完成电能计量数据异常识别参量的挖掘特征优化与配置。通过仿真数据对比表明,数据挖掘算法能够有效提升异常数据的识别响应指标与准确度指标,且全局稳定性得到同步提升,具备解决传统识别方法偏差较大的能力。