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%.

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.

Advanced Metering Infrastructure for Electric Vehicle Charging

The widely adoption of Electric Vehicle (EV) has been identified as a major challenge for future development of smart grids. The ever increasing electric vehicle charging further increases the energy demand. This paper reports the development of an Advanced Metering Infrastructure (AMI) as an effective tool to reshape the load profile of EV charging by adopting appropriate demand side management strategy. This paper presents a total solution for EV charging service platform (EVAMI) based on power line and internet communication. It must be stressed that the development of Third Party Customer Service Platform in this investigation facilitates a single bill to be issued to EV owners. Hence, EV owners understand their energy usage and thus may perform energy saving activity efficiently. Experiment and evaluation of the proposed system show that the throughput achieved is about 5 Mbps at 10 ms end to end delay in Power line Communication. By introducing two dimensional dynamic pricing and charging schedule, the proposed EVAMI successfully reduces 36% peak consumption and increases the “off peak” consumption by 54%. Therefore the EVAMI does not only reduce the peak consumption but also relocates the energy demand effectively.

Methods and Techniques of Electricity Thieving in Pakistan

The situation of electricity in Pakistan has been alarming from the last ten years. The deficiency in electricity has not only obstructed the business activities but also affected the domestic consumers, educational institutes and hospitals. Usually electrical power companies are liable for electricity shortfall and power interruption. However, electricity end consumers are also equally responsible behind strange shortfall and unusual power interruption. Frequently, the consumers use the heavy electrical equipment in their homes including heaters, geysers, irons and water motors which causes the more electricity consumption, load shedding and huge amount of bills. For escaping the huge amount of electricity bill, the consumers commit the illegal and unethical connections. The illegal usage of electrical power failed the power companies to plan schedule load shedding accordingly and the other side the damaged electricity wires or Pole Mount Transformer increased faults due to overburdening, which directly affected on extend power interruption. In addition that, responsible teams of electrical power companies cannot reach instantly to repair faults and prevent the theft. Electricity thieving is social crime committed by the consumers or meter readers which causes the electricity strange shortfall within country. This paper presents the practical demonstration about the common energy theft methods and techniques done by electricity consumers within their home and residential building. In Pakistan EPC (electrical power companies) deploy the traditional electromechanical meters for electricity consumption measurements, however, these meters do not have any real time communication. Therefore there are many easy ways to manipulate the meter reading as well as internal structural of metering system.

一种基于用电标识的新型用电量计量系统

详细的用户用电信息是推进节能减排、实施能源优化的关键。针对在获取精确的用电信息过程中存在的电力线干扰问题,文中提出了一种基于用电标识的新型用电量计量系统。该计量系统由用电标识端与采集计量端两部分组成。用电标识端通过ASK(Amplitude Shift Keying)数字调制为各用电器的用电信息进行独立编码,经电容耦合至电力线。采集计量端通过电力线载波通信对独立编码信息进行采集,并分析处理从而实现用电量计量。通过Multisim与MATLAB仿真软件对所提计量方案进行仿真验证,根据用电器特性可独立编码用电信息,采集计量端通过对独立编码数据分析处理可还原用电器的用电特性波形,实现较好的抗干扰性。

Smart Meters and Under-Frequency Load Shedding

In some countries, there exists a risk of power deficit in the EPS （electrical power system）. This is a very serious problem and there are various solutions to deal with it. A power deficit in the EPS leads to frequency decrease in the power system. A dedicated automation to load shedding is used to maintain proper EPS operation. For some time, it has applied a mechanism called demand-side response, which in case of an emergency situation allows for a ＂more civilized＂ rationing of electricity to customers, with their consent. Such programs require that the utilities pay the customers for their agreement. The author proposes a new solution, intermediate between strict ALS （acting relieving automation） and demand-side response programs, where the companies have to send information about the price of energy or control signals to households.

计及电量交易信息的用电碳计量方法

充分挖掘电碳耦合价值,构建电碳协同市场是实现碳达峰、碳中和目标的重要抓手。电碳信息的耦合依赖一套合理、有效的用电碳计量体系,但我国现行用电碳计量体系中尚未考虑电量交易信息的影响,不能完全厘清每个电量交易行为背后蕴含的碳排放责任。针对此问题,该文从碳排放流理论出发,提出一套计及电量交易行为的用电碳计量新方法。首先,根据碳排放流理论的计算特性,针对有损网络建立其无损等效网络模型;之后,将交易电量和非交易流电量拆解开来,并分别根据其电量来源独立核算其产生的对应碳排放责任。该文方法严格遵守直接和间接碳排放的总量守恒原则,能够厘清电量交易行为背后蕴含的碳排放责任转移,且能够兼顾碳排放因子的时空差异性量化需求,进而具备引导用户开展低碳需求响应的能力。基于PJM-5节点系统和我国某地市实际数据开展仿真分析,仿真结果验证该文方法的有效性。

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。

基于碳化硅电源的双芯智能电能表的可靠性测试研究

基于碳化硅电源的双芯智能电能表是新技术在工程领域特别是电力行业的重要尝试。针对其缺少可靠性检测标准的问题,文中根据现有智能电能表运行环境,同时结合碳化硅开关电源和双芯智能电能表特点,通过对电能表各项应力分析,提出了其可靠性检测方案及相应具体方法。提出的检测方案对于确定基于碳化硅开关电源的双芯智能电能表整机的可靠性指标具有十分重要的指导意义,从而实现提升智能电网技术水平,保障电网安全稳定运行的目的。

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.

一种不须停电且无电量损失的电能表更换方法

现有电能表更换技术普遍存在若干问题,实用性较差。为此,文章提出一种实用性很强的电能表更换方法,该方法基本步骤是通过换表线先行并入新表,然后拆离旧表,最后装上新表。该方法具有不须用户停电、不存在电量损失、电量交接简单、绝缘防护完善等优点。

电能计量自动化系统在电力营销中的应用探讨

现阶段,计量自动化系统逐渐成为电力发展一大趋势,将该系统用于电力营销中,不仅可以提高电网自动化水平,还能够达到节电保电的目的。计量自动化系统是集各级计量点与采集终点为一体的现代化应用平台,随着电力系统的日益发展,电能计量自动化系统在电力营销中的关键性作用凸显,因此,电力企业要根据自身发展需要及发展状况合理应用电能计量自动化系统,重视其在电力营销中的应用程度,在提供用电数据的基础上,提高电力企业经济利润。

电力碳排放计量网络溯源方法及计量分析

碳排放流理论在电力间接碳排放量计量中有效应用,电碳表等计量装置已试点部署,形成电力碳排放计量网络(简称电碳计量网络)。电碳计量网络具有数字化、网络化的特征,是一种新的计量方式,目前尚未有针对电碳计量网络的溯源研究及分析。该文在基于电能的碳排放流理论实现方法基础上,首先讨论用户碳排放量的计量属性,再通过对电碳计量网络中通信线路不确定度、电碳表不确定度、电碳计量算法不确定度的研究,提出电碳计量网络整体溯源方法,并对溯源方法进行分析,得出普遍贡献、电能有限影响、逐级递减3条结论,可为电碳计量网络的实际应用提供理论支撑,最后,利用实验室中部署的电碳表系统验证了文中提出的溯源方法及结论的有效性。

基于线损等效的视在功率和功率因数计算方法研究

分析了三相严重不平衡条件下现有功率因数的计算结果,指出了现有计算方法在反映实际线路利用率情况存在的不足。基于线路功率损耗等效原理,提出了一种能够准确反映实际线路利用率的功率因数和视在功率计算新方法。给出了现有智能电能表实现等效功率因数和视在功率计算的升级方案,同时以高准确度智能电能表作为测试平台,与现有功率因数进行三相非正弦不平衡试验条件下的对比测试。数据分析表明,与现有功率因数和视在功率相比,所提出的功率因数和视在功率新方法能够如实反映实际线路利用率情况,能够为功率因数的改善提供合理依据。

计及电力数据安全的智能合约上链方法及防篡改技术研究

随着“大云物移智链”等数字化技术在能源电力领域迅猛发展,大量新兴技术快速地在电网业务系统中进行创新应用,导致用电信息采集系统中数据交互更加频繁,从而出现数据经过流转后发生缺失、损坏等问题,进而导致业务数据公信力下降,且流转过程不清晰不透明,难以进行数据追溯溯源。针对用电信息采集系统数据可信度低、溯源难等问题,分析了区块链技术在用电信息采集系统应用情况,设计了区块链-用电信息采集系统三元结构模型,提出了一种采用区块链-用电信息采集系统三元结构的基于改进模型的实用型哈希算法的结构防篡改加密算法。仿真结果表明,区块链-用电信息采集系统三元结构的防篡改加密算法可提升数据质量进而提升业务数据公信力,同时通过该结构增强了数据的溯源能力,极大提升了用电信息采集系统数据在交互和使用过程的安全性。

智能物联电能表扩展功能模组设计

在能源转型和数字化革命的大背景之下,仅具备传统计量、收费、通信功能的智能电能表,已经无法支撑能源互联网快速发展带来的迫切需求。文中设计了一款具备硬件扩展功能的智能物联电能表,通过采用多芯、模组化的理念,设计各类模组的标准化接口,为扩展功能模组提供电源、通信接口以及原始采样数据,可满足电力用户多样化的应用需求。以需要开展电能质量分析的应用场景为例,设计了智能物联电能表用电能质量监测模组,并通过试验验证了扩展功能模组的功能及数据监测的准确性。

谐波条件下感应式电能表误差校验方法研究

在谐波存在的情况下,电流、电压工作磁通会随着谐波频率的增大而减小,驱动力矩也随之减小,使得电能表转速减慢,计量失准。为提升电能计量系统的准确性和可靠性,研究了谐波条件下感应式电能表误差校验方法。通过计算感应式电能表实际电能消耗,可以定量评估谐波对电能表计量误差的影响程度,由此得到谐波误差。结合谐波误差,在Budeanu功率定义的基础上,引入谐波特性系数,构建感应式电能表计量误差的校验模型,并采用基于功能驱动原理的赋权法确定电能表对各次谐波的重要计量特性系数,实现谐波条件下感应式电能表误差校验。实验结果表明,该方法校验后的电能读数实际电能值偏差均在0.02 kW·h以下,并且受温度的影响较小,在稳定性、变差和反应时间三个关键性能指标上均表现最佳。

基于电力大数据和天牛群算法的直流电能数字化计量方法

为了提高直流电能计量的准确性,基于电力大数据和天牛群算法提出一种直流电能数字化计量方法。利用多周期滤波算法对电力大数据进行处理,提取电压和电流的基波分量。通过谐波计量分析技术识别和分析电力信号中的谐波分量。设计直流电能计量流程,结合自适应梳状滤波器和天牛群算法,实现对电能的精确计量和修正。测试结果表明,采用提出的方法对直流电能进行计量处理时,电能计量相对误差值多数在10 W以下,最低误差值为6.6 W,能够提高直流电能计量的准确性,具备较为理想的计量效果。

电能计量中的自动化技术应用

电能计量系统属于电力管理系统的基础性内容,主要负责对各项基础性数据进行采集和计量,能够为后续运维与管理等工作的开展提供数据依据,是保证电力系统管理工作开展质量的关键所在。将自动化技术应用到电能计量中,能够在有效提高电能计量效率的同时,解决人工计量所存在的各种问题,保证电能计量精准度,会对我国电力系统应用与发展产生积极作用。通过对电能计量自动化技术应用优势的介绍,对自动化系统展开研究,并会在此基础上对自动化技术在电能计量中的应用展开深度探讨,旨在提高自动化技术应用水平,推动我国电能计量工作稳定性发展。

基于云计算的电力电能计量信息采集系统设计

本文指出随着电力行业的快速发展和电力需求的增长,电力电能计量成为电力行业中一个重要的环节。传统的电能计量系统存在数据采集方式不便、信息传输缓慢和计量数据不准确等问题,已经不能满足现代电力行业的需求。因此,本文基于云计算技术设计了一种电力电能计量信息采集系统,以期解决传统电能计量系统的问题,同时也为相关领域的研究提供一定的理论和技术参考。