Electrical injury: understanding the body's response

Studies of electrical injury are described in which the electrical field associated with the current is shown to be a source of damage, in addition to heat. It is shown that this result explains clinical observations that connective tissue is not harmed during electrical accidents, while skeletal muscles are destroyed. The researchers identified three cell categories, exhibiting three distinct types of response to the electric field     

660MW梯级供热机组耦合电锅炉运行优化

基于对660 MW梯级供热机组耦合电锅炉运行特性分析,提出一种确定机组实时运行最佳经济背压的方法.试验表明控制机组主蒸汽流量和外界热负荷工况,参考最佳经济背压运行能有效增加机组的输出功率,可提高机组运行热经济性.机组梯级供热改造后,供热能力提升约440 GJ.在保证对外供热负荷不变时,梯级供热可降低发电机功率86 MW...     

Electrical injury: mechanisms, manifestations, and therapy

Human contact with strong electrical power sources often results in complex injury patterns which have been difficult to explain and even more difficult for survivors to overcome. Fundamentally, there are two basic modes of tissue injury: direct effects of strong electric fields on proteins and cellular structures and indirect effects related to joule heating. Historically, tissue injury due to direct effects of electric forces have received no consideration with respect to understanding electrical injury. Recently, substantial progress has been made in understanding this aspect. The structural characteristics of nerve and skeletal muscle tissue renders them particularly vulnerable to injury by supraphysiological electric fields. How the injury manifests from the combination of thermal and electric effects depends on several variables including the tissue field strength, duration of exposure, frequency, and current path. This review describes the destructive changes to cellular structure resulting from exposure to commercial electrical power sources and the resulting manifestations at the organ system level. Finally, several important new therapeutic approaches to treat and possibly reverse the molecular alterations of electrical shock are discussed.     

Determination of criteria to find the quality of an electrical connection

A contact system is a nonredundant technical structure of electric railways that should provide uninterrupted power supply for railway vehicles. The failure of one part can lead to failure of the contact system. About 20% of damage to contact systems is due to inadmissibly high temperature at part of an overheated catenary. In this paper, normative indices are analyzed to determine the state of the terminal under operating conditions. The existing methods of thermal control are unable to determine the current heat state of an electric bolted connection with required accuracy. Heating control of electrical connections is suggested. To determine the state of the electrical connection, the factor of defectiveness due to heating is selected. As a result, criteria for determining the state of an electrical connection are obtained, which allows a methodology to be developed for monitoring the quality of an electrical connection.     

采用短距离无线通信技术的电气设备温度在线监测的实现

针对高压电气设备接触点发热的现象,对设备维护中发热点监测的方法进行分析,提出利用短距离无线通信技术,实现高压电气设备接触式在线温度监测的实施方案。     

电蓄热技术在张家口清洁供热领域的适用性研究

张家口是中国重要的清洁能源富集区之一,其清洁供热实施方案对全国具有示范作用。在介绍电蓄热技术原理的基础上,分析张家口某医院电蓄热式清洁供热改造工程的几种方案,并计算得出固体电蓄热方案具有良好的经济性;建议张家口应用互联网+电蓄热技术优化集中式和分布式清洁供暖实施方案,该方案可显著提高清洁能源消纳水平,对于实际工程的实施具有较大的参考价值。     

W-Cu触头材料的电寿命研究

研究了W-Cu系列触头材料的电弧烧损规律。触头材料的电弧烧损随开断次数的变化分为老炼、稳定和失效三个阶段，其中稳定阶段的长短是影响电寿命的决定性因素。还发现蚀头材料的电弧烧损主要是触点在断开和闭合的过程中，产生电弧或其它放电现象的热效应所造成的。材料的比热容、密度、熔点和电导率决定触头的电寿命。     

利用蓄热式电采暖提高电网风电接纳能力的研究

电能的特点是易传输不易存储,热能的特点是易存储不易传输,热力系统的时间常数远大于电力系统,对电供热系统功率的短期调整不会明显影响供热效果。下面结合蓄热式电采暖的特点和风电出力特性,提出利用蓄热式电采暖技术提高电网接纳风电能力,解决了部分地区冬季热电厂因供热影响发电出力、系统调峰容量减少与风电接入后对系统调峰容量需求增加的矛盾,提高电网运行的安全性。     

Dimensional soft tissue thermal injury analysis using transmission line matrix (TLM) method

The skin is sensitive to temperature change and the effect may not be significant while the temperature at the surface is below 44°C. However, higher surface temperatures (above 44°C) will further incur time burning and carbonization so that irreversible damage may happen. An investigation of the heating intensity and the duration of the exposure to the heating source suggested that when the surface temperature is greater than 51°C, the exposure time required to destroy the epidermis is so short that trans‐epidermal necrosis may occur. In this paper, we present one‐ and two‐dimensional numerical models based on transmission line matrix (TLM) method for a quantitative prediction of skin burn injury resulting from the exposure of the skin surface to a high temperature heat source. Transient temperatures are numerically estimated by solving the Pennes' bioheat equation, and the damage function denoting the extent of burn injury is calculated using the Arrhenius assumptions for protein damage rate. The TLM model is used to analyse the effects of exposure time and geometrical dimensions of mutlilayered skin, on the transient temperature distribution and damage extension. TLM results showed good agreement with other numerical sources, suggesting that TLM modelling can be used as a tool for an effective thermal diagnostic of burn injuries. Copyright © 2008 John Wiley & Sons, Ltd.     

考虑配电网容量约束和建筑热惰性的城市换热站电制热补热优化配置方法

北方地区市政供暖普遍存在热源、热网缺口和化石燃料依赖度高的问题,增量建筑的末端供热效果难以保障,而依靠传统配电网增容的方式一定程度上造成了社会资源的浪费。设计了一种面向城市换热站的电制热补热系统,提出了一种配电网“免增容”的城市换热站电制热补热优化配置方法。首先,阐述了电制热补热系统的设计结构,建立了制热设备和蓄热设备的模型与建筑热惰性模型。然后,通过两阶段优化方法,考虑设备投资与运行成本,以经济性为目标,建立了电制热补热优化配置模型。最后,以北京市石景山某居民区为研究对象通过Matlab进行仿真计算,研究结果表明,电制热补热优化配置方法可有效降低配电网负荷峰谷差,保障末端供热效果,并且具有较好的经济性,可为电采暖规划提供参考。     

Human element factors affecting reliability and safety

Many system reliability prediction methods are based solely on equipment failures, neglecting the human component of man-machine systems (MMS). These methods do not consider the identification of the root causes of human errors. The reliability and safety of industrial and commercial power systems and processes (i.e., MMS) are dependent upon human characteristics and many dependent and dynamic interactive factors. The consequences of human errors are very diverse and can range from damage to equipment and property, injury to personnel or fatalities, to disruption of scheduled system operation, all of which represent a significant cost to society. This paper focuses on accidents-injuries and the disruption of scheduled system operation caused by human element factors and shows that the human element is a very significant factor affecting the reliability and safety of electrical systems. The paper initially presents several case studies to reveal the frequency of human errors which disrupted scheduled computer and utility system operation. This paper also presents statistics on the injury accident rate in electric utilities and the number of days lost to injury accidents. It presents some of the factors that direct human behavior and discusses how these factors help identify the possible root causes of electrical accidents, using an accident-injury sequence model to determine the cause of human errors. Knowledge of human factors can be used to mitigate their impact on power system interruptions and injury accidents (e.g., increased productivity, increased reliability, decreased errors, increased safety, etc.)     

基于柔性负荷聚合的多方协作机制电采暖项目经济性分析

清洁供暖行业仍处于向市场化运作转变的过程中,电采暖投资运行依靠政府补贴,对电采暖项目经济性问题进行研究十分有必要.构建了蓄热式电采暖热源站经济性分析模型和聚合管理模型,对比了电采暖热源站进行聚合管理参与辅助服务前后的经济效益,结果表明对具有柔性调控潜力的电采暖负荷进行聚合管理参与辅助服务市场可以获得聚合收益,降低热源站...     

阀控式铅酸蓄电池中的氧循环与热失控现象

研讨了阀控式铅酸蓄电池在充电后期的主要反应和它们的热效应，论证了闭合氧循环在密封电池内通过两个途径实现，它们将大部分电能转化为热能而耗散，在散热不良的状况下，电池温度上升迅速，因自加速效应而会导致热失控现象。因此，对阀控式铅酸蓄电池充电必须严格控制条件以减少正极氧的析出，同时保证必要的散热条件。     

Main factors causing damage to the high-temperature heating surfaces used in power-generating boilers

Main factors causing damage to the high-temperature heating surfaces used in power-generating boilers are presented, as well as certain design shortcomings of boilers and specific features of their operating conditions due to which infliction of damage to their heating surfaces becomes most probable.     

Estimation of low-potential heat recuperation efficiency of smoke fumes in a condensation heat utilizer under various operation conditions of a boiler and a heating system

For enhancement of the natural gas utilization efficiency in boilers, condensation heat utilizers of low-potential heat, which are constructed based on a contact heat exchanger, can be applied. A schematic of the contact heat exchanger with a humidifier for preheating and humidifying of air supplied in the boiler for combustion is given. Additional low-potential heat in this scheme is utilized for heating of the return delivery water supplied from a heating system. Preheating and humidifying of air supplied for combustion make it possible to use the condensation utilizer for heating of a heat-transfer agent to temperature exceeding the dewpoint temperature of water vapors contained in combustion products. The decision to mount the condensation heat utilizer on the boiler was taken based on the preliminary estimation of the additionally obtained heat. The operation efficiency of the condensation heat utilizer is determined by its structure and operation conditions of the boiler and the heating system. The software was developed for the thermal design of the condensation heat utilizer equipped by the humidifier. Computation investigations of its operation are carried out as a function of various operation parameters of the boiler and the heating system (temperature of the return delivery water and smoke fumes, air excess, air temperature at the inlet and outlet of the condensation heat utilizer, heating and humidifying of air in the humidifier, and portion of the circulating water). The heat recuperation efficiency is estimated for various operation conditions of the boiler and the condensation heat utilizer. Recommendations on the most effective application of the condensation heat utilizer are developed.     

电场对带电颗粒在电连接器表面沉积过程的影响

基于尘土颗粒周围电场与其在电接触表面沉积的密切联系导致电接触可靠性下降甚至接触故障,分析了电连接器自身及外加电场对尘土颗粒运动产生影响的过程和机理,提出了衡量电连接器对颗粒吸引能力的判据和计算方法.仿真实验表明,该吸引能力与电连接器两端电压和距离有关,颗粒运动趋势与其进入电场时间有关,而与其所带电荷极性无关.     

基于仿真模拟的空气源热泵电采暖经济技术分析

为助力采暖电能替代工作推进,首先建立了冷凝器、蒸发器、压缩机、膨胀节流阀等热泵部件的数学模型和仿真子系统,构建热泵机组仿真系统;然后对多种品牌和型号热泵的供热模式进行仿真,将主要热泵性能参数的模拟值与相应的实测值进行对比,以验证仿真的准确性;最后基于搭建的热泵仿真系统,计算北京地区典型采暖季单位采暖面积空气源热泵的终端能耗量、二氧化碳排放量、运行成本、总成本,并与蓄热式电暖器、散煤采暖、分散式燃气采暖的数据进行对比。研究表明,热泵性能参数的模拟值与相应实测值的误差在可接受范围内,空气源热泵是最值得推广的分散式采暖技术。     

户外高压隔离开关电触头温升机理研究

针对110 kV以上电压等级隔离开关电触头易发热的现象,以具有代表性的GW4A-126型高压隔离开关为对象,研究电触头的温度特性。在简化电触头结构后,应用有限元分析软件ANSYS 建立触指部分的三维模型,在不同接触电阻、接触面积和负载电流的条件下对模型施加载荷,根据得到的温度场分析触指最高温度的变化情况。仿真结果表明：接触压力、接触电阻、接触面积、负载电流和触点材料是影响电触头温度的主要因素;接触电阻和负载电流越大,电触头温升幅度越明显;增大接触面积可以提高电触头的热稳定性。     

严寒地区分散式电采暖负荷可调节特性量化建模研究

我国北方地区冬季采暖需求巨大,这为利用电采暖解决大气污染及大规模风电消纳等问题提供了巨大的发展空间。但是,现有研究缺乏对分散式电采暖负荷可调节能力量化建模及评估的关注。由此,建立了基于多层建筑物传热过程的电采暖负荷可调节特性模型,并基于严寒地区实测数据,定量分析了多层建模分散式电采暖负荷功率-时间维度的可调节能力及其影响因素,为进一步控制电采暖负荷满足电力系统多种灵活调度需求奠定了良好基础。     

熔渗法AgW（75）触头材料研究

电触头作为电器设备的关键元件之一,既是载流体,又是机械零部件,要求具有良好的导电导热性、耐电孤烧损、抗熔焊、低而稳定的接触电阻、有一定的强度和易于机械加工等。本研究采用粉末冶金熔渗技术制备AgW（75）电触头材料,对其进行复压、复烧,并测量了其力学物理性能和显微组织。结果表明,粉末冶金熔渗技术与复压复烧相结合制备的AgW（75）触头材料的相对密度高,硬度达到国家标准要求,但材料收缩性大。