Application of Extended Kalman Filter to the Modeling of Electric Arc Furnace for Power Quality Issue

Electric arc furnaces(EAFs)represent one of the most disturbing loads in the subtransmission or transmission electric power systems.Therefore,it is necessary to build a practical model to descript the behavior of EAF in the simulation of power system for power quality issues.This paper deals with the modeling of EAF based on the combination of extended Kalman filter to identify the parameter of arc current and the power balance equation to obtain the dynamic,multi-valued u-i characteristics of EAF load.The whole EAF systems are simulated by means of power system blockset in Matlab to validate the proposed EAF model.This model can also be used to assess the impact of the new plant or highly varying nonlinear loads that exhibit chaos in power systems.

Assessment of Electric Power Qualityin Ships' Modern Systems

The paper deals with the selected problems of electric power quality in ships’ modern systems. In the introduction the fundamentals of electric power quality assessment, such as the relations and consequences among power quality phenomena and indices, secondly as the methods and tools as well as the appropriate instrumentation, have been shortly presented. Afterwards, the basic characteristic of power systems on modern ships has been given. The main focus of the paper is put on the assessment of electric power quality in ships’ systems fitted with converter subsystems. The state of the art and actual tendencies in the discussed matter have been shown. Some chosen experimental results, based on the research carried out under supervision of the author, have been presented, too. Finally, some concluding issues have been shortly commented on.

Electric Power Quality Analysis 6-10/0.4 kV Distribution Networks

The paper reports quality analysis and evaluation at 6 - 10/0.4 kV low-voltage distribution grids in Uzbekistan. Power quality frequently does not correspond to the rated value which is largely due to unbalanced phase loading in grids and which also results in increased power loss. The study of the asymmetrical operating modes of the rural distribution networks of 0.4 kV was conducted in three steps: measurement, calculations and analysis of relevant data;providing practical guidelines and finally, implementing instruments to normalize grid operation. Measuring was conducted using certified instrumentation analyzer “MALIKA” designed by authors. The study and analysis of additional power losses as the function of indicators of asymmetrical features of voltage and current in operating 0.4 kV grids reveals that, quality of electric power at grids under investigation, merely does not meet the requirements of the Interstate Standard.

Power Quality Issues Concerning Photovoltaic Generation and Electrical Vehicle Loads in Distribution Grids

The high utilization level of renewable generation including residential photovoltaic (PV) systems together with the uncontrolled charging of electric vehicles (EVs) can have a significant impact on load characteristics in distribution networks. Harmonic content of PV generation, EV charging loads, and their influence on power quality indicators in residential distribution networks are discussed in this paper. For investigating likely power quality scenarios, PV generation and EV charging measurement results including current harmonic amplitude and phase angle values are used and compared with present load characteristics. Different modelling scenarios are analysed and a simplified model of harmonics in PVs and EVs is offered. The results of the study show moderate additional harmonic distortion in residential load current and voltage distortion at the substation’s busbar when PV generation and EV loading are added. The scenarios presented in this paper can be further used for modelling the actual harmonic loads of the PVs and EVs in distribution networks.

Global Harmonic Rate Assessment in the Electricity Distribution Network in Niamey City:Case Studies of Domestic,Industrial and Hospital Substations

Like others countries of the world, in Niger also, we are witnessing an increasing use of non-linear electric loads in the domestic, hospital and industrial sectors. However, these loads degrade the shape of the electrical signal and cause disastrous effects to the equipment of the distribution system and the devices which are connected to the network. This article highlights the presence of electric harmonics in the distribution network in Niamey city. In order to do this, measurements were taken at the secondary level of the substations using an energy quality analyze r (FLUKE 1735). By using this measuring instrument, we quantified the voltage and current Total Harmonic Distortion (THD) in the three substations. The results obtained show that, although the statutable rates set by the standards are not exceeded for phase conductors, the neutral contains a very critical percentage of distortion on the residential and hospital substations. Moreover, this assessment made it possible to observe the variation of harmonics in the presence of voltage drops.

The New Brazilian Power Quality Standard and a Low Cost Device Meter

This paper presents an overview about the new Brazilian Power Quality Standard and provides a low cost device PQ meter, developed and implemented to assist the national campaign to assess the Brazilian power quality indices, unknown until now. This work contributes with the search of a low cost devices PQ meter for a cost sensitive market, and introduces the new Brazilian Power Quality Standard to the international community.

Impact Analysis of Off-board Charger to Power Quality

In this paper, we tested the entire charging process of a single off-board charger in one charging station in Beijing. Among the testing data, we chose the typical power quality parameters and compared them with national standard. Then we drew conclusions as follows: 1) Electric vehicle battery is the capacitive load. It can export reactive power when charging. 2) In the charging process of the off-board charger, indicators of voltage deviation, frequency deviation, power factor, and voltage distortion rate are qualified. 3) Off-board charger produces odd harmonics in the charging process, and with increasing harmonic order, harmonic content reduces. There is a certain amount of high-order harmonic in off-board charger, mainly distributing around 6650 kHz. 4) Generated harmonics of the actual device, the harmonic is mainly reflected in the current, voltage, only a small distortion.

Harmonic Measurement and Analysis during Electric Vehicle Charging

This paper presentsand describes harmonic measurement and analysis of studying harmonic propagation during electric vehicle (EV) charging. The measurement study is performed on a golf cart and two modern type of EVs. Harmonics from a single EV charging and a group of EV charging was measured. The voltage and current waveform during the charging was captured and analyzed to investigate the harmonic components that exist in the electrical system. Total current harmonic distortion (THDi) and total voltage harmonic distortion (THDi) were both calculated. Modern electric vehicles are found to release low THDi but higher THDv compared to a golf cart. On the measurement study during charging of? a group of EV, it is found that the summation of THD is not linear with a number of vehicles. The finding of the study reveals that harmonic contamination from EV charging on electrical grid is not as critical as thought by most of power system researchers and engineers.

Power Quality Improvement and Signal Conditioning of PV Array and Grid Interfaced Off-board Charger for Electric Vehicles with V2G and G2V Capabilities

In this work,we present a photovoltaic(PV)-based off-board charging system integrated with the grid using a voltage source converter(VSC).The control of the grid-tied off-board charger is derived from the joint logarithmic hyperbolic cosine robust sparse adaptive filter(JLHCAF)algorithm.This algorithm effectively tracks the fundamental component of the load current in a short duration,providing a good dynamic response.Due to its robustness against impulsive interference,the JLHCAF outperforms other sparsity-aware robust algorithms The cascaded proportional-integral(PI)controller is used to control the bidirectional buck-boost converter for electric vehicle(EV)charging/discharging,which acts in buck operation if the EV is being charged and in boost operation if it is discharged.The reference DC link voltage for the controller is derived by using adaptive MPPT technique.The bidirectional properties of the system enable various functions,including grid-to-vehicle(G2V),vehicle-to-grid(V2G),PV source-to-grid(PV2G),vehicle-to-home(V2H),and PV source-to-vehicle(PV2V)operations.Additionally,the system can supply power to critical nonlinear loads.The control strategy ensures compliance with the power quality requirements set by the IEEE standard,as demonstrated in the results.To validate the effectiveness of the proposed system,we conducted tests under dynamic conditions by disconnecting and reconnecting household loads.Furthermore,the off-board charging system was subjected to actual conditions,such as variations in solar PV insolation,and its steady-state performance was evaluated through simulation and laboratory experimental prototypes.The results,including total harmonic distortion(THD),support the validation of the developed charging system.

基于RPC的光储接入牵引供电系统协调控制方法

为将光伏发电接入牵引供电系统进行有效利用,同时兼顾牵引供电系统电能质量改善及列车再生制动能量回收利用,提出了一种基于铁路功率调节器的光储系统接入牵引供电系统的协调控制方法.首先,搭建基于铁路功率调节器的光储系统接入牵引供电拓扑结构,并对其电能质量补偿机理进行理论分析;在此基础上,充分考虑光储系统的运行条件以及列车牵引、制动、空载或惰行工况,提出光储系统接入牵引供电的联合协调控制方法,实现了“光+储+荷”三者间的协调控制、牵引供电系统负序的动态补偿以及谐波的有效抑制;在RT-Lab实时仿真系统中建立了基于铁路功率调节器的光伏接入牵引供电系统仿真模型,并结合实际光照和牵引工况数据验证本文所提出的系统结构以及协调控制方法的有效性.结果表明:本文所提出的系统结构以及协调控制方法能够实现牵引供电系统中光储系统的有效接入,再生制动能量回收率提升至86.7%,功率因数提升6.4%,对谐波特别是高次谐波含有率有较大改善,满足光伏电能高效消纳及综合利用、电能质量动态综合补偿、再生制动能量回收多重需求.

面向功率冲击平抑的岸电系统储能型电能调控装置容量优化配置策略

针对港口岸电系统负荷侧存在的冲击性功率等电能质量问题,提出一种储能型电能调控装置容量优化配置方法。介绍港口岸电系统及储能型电能调控装置拓扑结构,并分析冲击性负荷运行特征;探讨负荷运行工况与功率因数控制目标之间的关系,根据电池荷电状态与负荷运行工况,提出储能型电能调控装置多类型运行工况自适应容量设计的补偿控制策略;建立储能型电能调控装置技术-经济模型,通过在技术模型中考虑岸电系统电能质量的要求建立容量模型,经济模型提供评估寿命成本和效益的方法。基于某港口岸电负荷实测数据,验证所提方法的有效性。

高功率密度电机制造质量提升方法

近年来,我国电动汽车和新能源汽车等高新技术产业的蓬勃发展,高功率密度现已成为电机的一个关键设计指标,其应用优势包括:重量轻、体积小及输出功率大等。但是在促进电机高功率密度化发展的过程中,也面临着一系列的问题,如:加工制造难度大、电机内部发热增高等,这些问题都在很大程度上影响到电机制造的质量和运行的安全性。基于此,本文对上述问题进行深入分析,采取针对性的方法来切实提高高功率密度电机制造质量,从而推动我国电机产业的可持续发展。

三相电力弹簧的无源控制策略研究

针对太阳能、风能等新能源设备大规模并入电网造成的电能质量下降问题,近年来出现了电力弹簧(ES)的概念。依据推导出的三相电力弹簧(TPES)的数学模型,搭建了对应的系统模型,依据无源控制(PBC)理论,分析了系统的无源性,并分别采用传统PI控制和无源控制验证了三相电力弹簧能够维持关键负载(CL)电压的稳定。通过仿真和实验验证,在有功功率变动工况下,无源控制的超调量远远低于PI控制的13.7%,调节时间0.03 s也低于PI控制的0.07 s,静差率0.0002%也小于PI控制的0.08%,表明无源控制的动态性能和静态性能都更出色。此外,相比于传统的PI控制,无源控制所需参数更少,控制系统结构更加简单。

电动汽车充电站群电能质量协同监测技术

为解决现有电能质量监测技术存在的监测范围小、精度低的问题,优化设计电动汽车充电站群电能质量协同监测技术。根据电动汽车充电站群的组成结构,构建充电站群模型,模拟充电过程。针对电能质量指标配置相应的电能质量监测点,协同采集与处理电动汽车充电站群暂态信号,通过对扰动、谐波/间谐、电压偏差、频率偏差等指标的计算,得出电能质量的协同监测结果。通过与现有监测技术的对比,所设计监测技术的监测范围扩大了1306.24m^(2),且监测误差更低。

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。

电气控制系统中电子技术应用的相关研究

科学技术的进步,为电子技术的升级与发展提供了有力支持。将电子技术应用到电气控制系统当中,不仅可以加强电子器件的控制,还可以保证整个电气控制系统操作的精准性,使整个系统长时间维持在稳定运行状态。重点围绕电气控制系统中的电子技术应用展开论述,旨在借助电子技术的应用优势,提高电气控制系统的运行质量。

多措并举推动电力企业对外设计咨询高质量发展

近年来,受应对气候变化、局部能源危机和地缘政治紧张等因素影响,全球能源绿色低碳转型目标不断提升,步伐进一步加快。基于全球能源转型与发展新形势,结合我国对外设计咨询“走出去”新特征,本文对电力企业对外设计咨询高质量发展存在问题进行了深入分析,并提出有针对性的对策建议。研究认为,我国电力企业应逐步实现从“市场创造”向“价值创造”的转型,通过夯实对外设计咨询专业基础、完善人才培养体系、开展功能性并购等方式,多措并举推动设计咨询行业高质量发展。