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市内变电站接地系统的设计和分析

电网与清洁能源 2016年第12期32卷 28-33页

作者：周亮徐骏刘垚付龙海李业旭 farid paul dawalibi 国网上海市电力公司经济技术研究院上海200120 国网上海电力设计有限公司上海200025 北京加华赛时电力安全技术有限公司北京100080

为了更好地进行市内变电站的设计和分析,介绍了市内变电站接地系统的基本设计流程,重点讨论了进行市内接地系统设计分析与常规郊区接地系统相比需考虑和出现的新问题。分析结果表明,与常规的接地系统相比,在进行市内接地系统设计时除了... 详细信息

为了更好地进行市内变电站的设计和分析,介绍了市内变电站接地系统的基本设计流程,重点讨论了进行市内接地系统设计分析与常规郊区接地系统相比需考虑和出现的新问题。分析结果表明,与常规的接地系统相比,在进行市内接地系统设计时除了要考虑各种常规因素外,还需考虑可能的多块土壤结构、各电压等级电缆在故障电流分布计算中的影响,以及考虑电站入地电流对周边构筑物以及民用设施的安全影响等方面,否则会对电站评估安全计算结果带来显著的误差,遗漏周边安全性评估等,造成安全隐患。

关键词：市内接地系统故障电流分布 GIS 土壤结构传导干扰地电位升

Electrostatic Field and Potential Generated by Arbitrarily-Oriented Line and Surface Sources with Additional External Electric Fields in Air

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Electrostatic Field and Potential Generated by Arbitrarily-O...

Measurement and Computation of Induced Noise Levels in Telephone Lines Due to Harmonics in Nearby Power Lines

2011 World Congress on Engineering and Technology(CET 2011)

作者： Simon Fortin farid P.dawalibi Safe Engineering Services ＆ technologies ltd. 3055 Blvd. Des Oiseaux Laval Québec H7L 6E8 Canada

This paper presents a new numerical method to calculate the electrostatic field and potential generated by arbitrarily-oriented line and surface sources with additional external electric fields in air. In the analysis, the soil is simplified as a semi-infinite metallic medium. The metallic objects can be connected to ground to keep them at zero potential or can be floating with a known energized potential or leakage current. This approach can be used to simulate the electric field and potential distribution around substations, power plants, transmission line towers, or buildings under a huge charged cloud in extreme conditions, in order to investigate lightning protection scenarios. The electric field generated by the charged cloud can be represented by an external electric field in this type of simulation. In the paper numerical results are presented for various configurations such as conductor systems, parallel plates, multiple plates forming a closed box and a complex system simulating a substation including bus bars, metallic supports and lighting protection masts under a huge charged cloud. Typical results are validated with available analytical methods or valid numerical methods.

关键词： Electric field scalar potential HVDC transmission lines substations HVDC substations power plants.

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Measurement and Computation of Induced Noise Levels in Telep...

The Fourth Asia-Pacific Conference on Environmental Electromagnetics

作者： Robert D.Southey farid P.dawalibi Safe Engineering Services ＆ technologies ltd.1544 Viel Montreal QuebecCanadaH3M 1G4 Safe Engineering Services ＆ technologies ltd.1544 Viel Montreal QuebecCanadaH3M 1G4

＜正＞This paper presents a real case study which includes measurement and computation of noise levels on telephone cables due to harmonics in nearby power lines. The objective of the study is to find the most efficient and economic mitigation measures to reduce the noise levels. A circuit model has been built and induced noise levels computed. Computation results are compared with the measurement data and they are in general agreement. Mitigation measures are proposed and will be examined in the second phase of the study.

关键词： inductive coupling circuit noise power influence harmonics

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电磁干扰领域中最新分析及计算技术

电力设备 2001年第4期2卷 29-33页

作者：马金喜 farid P.dawalibi 加拿大SES安全工程技术公司

通过实例阐述了电磁干扰问题中的分析与计算技术,并介绍了在此领域中用于分析与计算的软件工具。

关键词：电磁干扰瞬态干扰雷击分析设备保护

Analysis of a Large Grounding System and Subsequent Field Test Validation Using the Fall of Potential Method

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Energy and Power Engineering 2013年第4期5卷 1266-1272页

作者： Huan Huang Hualin Liu Hong Luo Hao Du Yi Xing Yexu Li farid P. dawalibi Haijun Zhou Longhai Fu Guizhou Electric Power Test & Research Institute Guiyang China Safe Engineering Services & technologies ltd Blvd. Des Oiseaux Laval Québec Canada

This paper examines various aspects of the design process and subsequent field test measurements of a large and complex substation grounding system. The study and measurements show that soil layering and lead interference can have a significant impact on the appropriate test location that yields the exact substation ground impedance. Applying a specific percentage rule such as the 61.8% rule for uniform soils to obtain the true ground impedance may lead to unacceptable errors for large grounding systems. This poses significant problems when attempting to validate a design based on raw test data that are interpreted using approximate methods to evaluate substation ground impedance, and determine ground potential rise (GPR), touch and step voltages. Advanced measurement methodologies and modern software packages were used to obtain and effectively analyze fall of potential test data, compute fault current distribution, and evaluate touch and step voltages for this large substation. Fault current distribution between the grounding system and other metallic paths were computed to determine the portion of fault current discharged in the grounding system. The performance of the grounding system, including its GPR and touch and step voltages, has been accurately computed and measured, taking into account the impedance of the steel material used of the ground conductors and circulating currents within the substation grounding system.

关键词： Ground Resistance Fall-of-Potential Ground Impedance Measurement Ground Potential Rise Ground Potential Difference Touch Voltage Step Voltage Steel Conductors

Study of the Physical, Mechanical and Thermal Properties of Banana Fiber Reinforced HDPE Composites

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Materials Sciences and Applications 2020年第4期11卷 245-262页

作者： Budrun Neher Rakib Hossain Kaniz Fatima M. A. Gafur Md. Abul Hossain farid Ahmed Department of Physics Jahangirnagar University Dhaka Bangladesh Department of Physics Bangabandhu Sheikh Mujibur Rahman Science & Technology University Gopalganj Bangladesh PP and PDC Bangladesh Council of Scientific and Industrial Research Dhaka Bangladesh

Natural fiber reinforced composite materials are replacing the conventional materials, owing to their excellent physical, mechanical, electrical, and thermal properties. Also they increase biodegradability, reduce cost and decrease environmental pollution and hazards. In this study, obsolete high density polyethylene (HDPE) has used as polymer matrix and banana fiber as reinforcement material. Composites (5%, 10%, 15% and 20% of fiber contents) were made by hot press molding method by using paul-Otto Weber Hydraulic press machine. The physical, mechanical and thermal properties of banana fiber-HDPE composites were studied and investigated the increment or decrement nature of different properties due to addition of banana fiber in BF-HDPE composites. The bulk density of composites increased with the increase wt. (%) of fiber content in composites. Water absorption ability of banana fiber and BF-HDPE composites also increased with the increase of wt. (%) of fiber content in composites and with socking time. Tensile strength of the BF-HDPE composites increased with the increase of fiber content in both cases (continuous aligned fiber orientation and continuous bidirectional fiber orientation). Moreover, the tensile strength of BF-HDPE composites with continuous aligned fiber orientation was greater than that of continuous bidirectional fiber orientation. At first, the flexural strength increased for 5% BF-HDPE composites then the value decreased for other higher compositions. The flexural strength of continuous aligned fiber orientation was slightly greater than that of continuous bidirectional fiber orientation and composite with 5% banana fiber showed better flexural properties than others. Leeb’s rebound hardness decreased with the increase of fiber addition. Different thermal properties like TG/DTG, DTA of the obsolete HDPE and BF-HDPE composites were studied using thermo gravimetric analyzer and it was found that composite with 20% fiber content was more thermally

关键词： BF-HDPE Water Absorption Tensile Strength Hardness TG-DTG

Effects of low intensity laser irradiation phototherapy on dental pulp constructs

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World Journal of Stomatology 2013年第1期2卷 12-17页

作者： Amr M Elnaghy Peter E Murray paul Bradley Melissa Marchesan Kenneth N Namerow Amany E Badr Youssry M El-Hawary farid A Badria Conservative Dentistry and Endodontics Department Faculty of Dentistry Mansoura University Mansoura 35516 Egypt Department of Endodontics College of Dental Medicine Nova Southeastern University Fort Lauderdale FL 33328-2018 United States Department of Orofacial Pain College of Dental Medicine Nova Southeastern University Fort Lauderdale FL 33328-2018 United States Department of Oral Biology Faculty of Dentistry Mansoura University Mansoura 35516 Egypt Department of Pharmacognosy Faculty of Pharmacy Mansoura University Mansoura 35516 Egypt

AIM: To investigate low intensity laser irradiation phototherapy(LILIP) on the proliferation, mineralization and degradation of dental pulp ***: Stem cells from human exfoliated deciduous teeth(SHED) were grown to confluence and seeded on collagen scaffolds to create dental pulp constructs. LILIP was delivered to the dental pulp constructs using an 830 nm GaA IAs laser at an output power of 20 m W. The LILIP energy density was 0.4, 0.8, 1.2, and 2.4 J/cm2. After 8 d, the cell proliferation and degradation within the dental pulp constructs were measured using histologic criteria. After 28 d, the effect of LILIP on SHED mineralization was assessed by von Kossa ***: SHED proliferation within the dental pulp constructs varied after exposure to the 0.4, 0.8, 1.2,and 2.4 J/cm2 LILIP energy densities(P < 0.05). The maximum proliferation of SHED in nutrient deficient media was 218% after exposure to a 1.2 J/cm2 LILIP energy density. SHED grown in nutrient deficient media after exposure to a 0.4, 0.8, and 1.2 J/cm2 LILIP energy density, proliferated by 167-218% compared to the untreated(non-LILIP) control group(P < 0.05).SHED exposed to a 0.4, 0.8, and 1.2 J/cm2 LILIP energy density, and grown in optimal nutritional conditions and proliferated by 147%-164% compared to the untreated(non-LILIP) control group(P < 0.05). The exposure of SHED to the highest LILIP energy density(2.4 J/cm2) caused a reduction of the cell proliferation of up to 73% of the untreated(non-LILIP) control(P < 0.05). The amount of mineral produced by SHED increased over time up to 28 d(P < 0.05). The 0.8 and 1.2J/cm2 LILIP energy densities were the most effective at stimulating the increased the mineralization of the SHED from 150%-700% compared to untreated(nonLILIP) control over 28 d(P < 0.05). The degradation of dental pulp constructs was affected by LILIP(P <0.05). The dental pulp constructs grown in optimal nutritional conditions exposed to a 0.8 J/cm2 or 1.2 J/cm2 LILIP e

关键词： Dental pulp cells Proliferation Low intensity laser Low intensity laser irradiation phototherapy Stem cells from human exfoliated deciduous teeth