台区线损管理瓶颈的突破

随着台区线损精益化管理的逐步深入,台区线损承包人为完成台区线损考核指标弄虚作假的现象时有发生,使台区线损统计失真。问题的关键是公司线损管理层不掌握台区线损统计中的供电量,这也是制约公司对台区线损进一步深入管理的一个瓶颈。廊坊供电公司从科技化管理方面入手,用时两年建设了台区集中抄表系统和负控系统,通过发布台区供电量的方式来堵塞线损管理环节出现的漏洞,从电源侧将线损管理的压力真正传递到台区管理人员,从而达到降损目的。     

不拆高压引线测量耦合电容器介质损耗和电容量

针对耦合电容器拆高压引线传统预防性试验的不足,根据不拆高压引线测量耦合电容器介质损耗和电容量值的试验方法,通过对南雁变南仙4367线等4条线路实测,与传统试验数据进行了对比分析,证明该方法可行有效。     

From defects creation to circuit reliability - A bottom-up approach (invited)

This paper presents a theoretical framework about interface states creation rate from Si-H bonds at the Si/SiO₂ interface. It includes three mains ways of bond breaking. In the first case, the bond can be broken thanks to the bond ground state rising with an electrical field. In the two others cases, incident carriers will play the main role either if there are very energetic or very numerous but less energetic. This concept allows us physically modeling the reliability of MOSFET transistors, and particularly NBTI permanent part, and Channel Hot Carrier (CHC) to Cold Carrier (CCC) damage. Finally, the translation of these physical models into reliability spice models is discussed. These models pave the way to Design-in Reliability (DiR) approach which seeks to provide a quantitative assessment of reliability - CMOS device reliability in this case - at design stage thereby enabling judicious margins to be taken beforehand.     

检定S型短型热电偶的4种不同冷端补偿方法之比较

检定长度在200～700 mm范围内的S型热电偶时,由于参考端温度大都处于室温或者波动的温场之中,需要将参考端温度恒定在0℃或采取修正、补偿等措施进行修正。现采取检定中最常用的4种不同的冷端补偿方法检定同一支S型短型热电偶,对结果进行比较分析,得到这4种不同的冷端补偿方法的优劣性及其准确度排序。结果表明,将参考端应用达到一等标准热电偶准确度水平的同极性热电偶丝延伸至参考端恒温器方法能获得较为理想的补偿效果。     

两台变压器的经济运行对节能降损的影响分析

随着能源的日益短缺,各行各业对节能降损越来越重视.在电力行业中,配网损耗中的60％是由变压器贡献的,因此实现变压器的经济运行对用电企业的节能降损具有重要要义.以江门地区某工厂为实例进行了计算论证,针对性的提出了两台同容量和不同容量变压器经济运行的方法.     

Evaluation of wind load integration in disproportionate collapse analysis of steel moment frames for column loss

The design of steel structures, in most cases, depends majorly on the level of wind loads which are prescribed by codes and regulations and are used in the structural analysis due to the fact that steel structures being light and ductile systems are strongly affected from a slight difference in the values of wind loading. During the last decades, disproportionate collapse analysis has become of major interest mainly due to the increasing number of failures occurring in that pattern. Commonly accepted guidelines and methods of analysis have been produced, the most dominating of which being the Department of Defense Facilities criteria or DoD. In the DoD, as well as in other criteria, the event of a column loss is suggested as the modeling scenario which has to be sustained by a structural system in order to be robust. However, all the guidelines so far have disconnected the column loss analysis from wind loads and have only performed it for gravity loading. This paper presents the dynamic time history disproportionate collapse analysis of steel frames, including various levels of wind loading. Interesting aspects are discussed through the parametric analysis of five different numerical examples of moment resisting frames.     

Experimental investigation on a parabolic trough solar collector for thermal power generation

Developing solar thermal power technology in an effective manner is a great challenge in China.In this paper an experiment platform of a parabolic trough solar collector system(PTCS) was developed for thermal power generation,and the performance of the PTCS was experimentally investigated with synthetic oil as the circulate heat transfer fluid(HTF).The solar collector's efficiency with the variation of the solar flux and the flow rate of the HTF was identified.The collector efficiency of the PTCS can be in ...     

Effect of heat treatment on mechanical properties of heavily cold-rolled Fe-6.5wt%Si alloy sheet

Fe-6.5wt%Si alloy has excellent soft magnetic properties,but it is hard to be cold-rolled due to appearance of ordered phases in this alloy.In this paper we report that ultra thin Fe-6.5wt%Si sheet of 0.05 mm thick was obtained by heavily cold rolling.By means of optical microscope,micro-hardness indenter,instron,SEM and X-ray diffraction,the effect of heat treatment on mechanical properties of this alloy sheet was investigated.The heavily cold-rolled sheet exhibits some extent of ductility.The ultimate ten...     

PWM激励下异步电机铁耗等值电阻模型

通过分析PWM激励下异步电机铁耗变化的特点,提出了一种综合考虑电机运行工况和PWM波形特性的铁耗等值电阻模型。基于铁耗分离原理,使用三个电阻分别等效电机铁耗的磁滞分量、经典涡流分量和异常涡流分量,并推导了正弦激励下各个电阻分量的表达式;进而通过分析PWM激励与正弦激励下铁耗间关系,对正弦激励下铁耗模型进行修正,获得PWM激励下铁耗模型;最后提出了确定该模型参数的实验方案。所建模型中各个电阻分量随电机运行频率和PWM波形的调制系数变化而变化,且变化规律各不相同,提高了电机铁耗计算的准确性。仿真和实验验证了该模型的正确性和有效性。     

Power loss minimization considering short‐circuit capacity in distribution system with decentralized distributed generation

In the future, a large number of distributed generators are expected to be connected to the distribution system. However, with the connected capacity of distributed generation (DG) increasing, the problems of short‐circuit capacity (SCC) over the interrupting capacity of the circuit breaker (CB) and power loss increases due to reverse power flow from DG are inevitable. In this paper, a reconfiguration methodology based on an optimal algorithm is applied to the distribution system with DG to minimize power loss, taking into account the SCC. Moreover, in order to further reduce the loss, the daily load variation is also considered and the optimal model decided by calculations. Finally, to illustrate its application, the methodology is applied to a case study of a 33‐bus system with decentralized DG units. The results show that this method is obviously able to reduce power loss and make the network operate in the optimal mode with normal load variation, at the same time decreasing the SCC within the interrupting maximum of the faulty CB. Moreover, the whole voltage profile is also improved. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.