Effects of low radiation on the power quality of a distributed PV-grid connected system

We have previously investigated effects of radiation levels on power quality of a number PV-grid interactive systems in Thailand, in terms of harmonics and voltage variation at the point of common coupling (PCC). In this paper, we focus on the nature of components of complex power (actual, reactive and apparent power) of inverter output of a PV-grid interactive system due to low radiation, below 400 W/m². The system being investigated has an array of 4.2 kWp and representative of roof top units. It is observed that a PV array supplies increasing real power, in magnitude and as percentage of complex power, at high values of radiation. At low radiation level when the array does not provide enough output power, reactive power is drawn from distribution transformer and fed into an inverter and loads. Based on results from the test site and long term radiation data of Bangkok, we then estimate energy available from low radiation from a hypothetical PV-grid interactive unit in Bangkok of a similar size. It can be seen that for a tropical climate like Thailand a significant amount of energy, 20–30% of radiation energy, is in the form of reactive power. Methods must be devised to capture this low radiation energy and converted into real power form.     

关于变压器二次额定电压的计算

推导了变压器二次负载电压的计算公式,建议由此公式代替以往原理书中惯用的近似公式。利用此公式绘制和分析了不同功率因数额定负载时的相量轨迹图。     

国产掘进机在龙门滩引水隧洞施工中的应用

在长隧洞的施工中，采用掘进机施工的工程越来越多，特别是国外掘进机的引进，加快了长隧洞工程的开发。而国产掘进机由于其性能和材质方面的原因，存在着一定的技术缺陷．通过国产SJ-45型掘进机在龙门滩工程的施工应用，分析和总结了SJ-45型掘进机的机械性能和存在的技术问题及处理结果，以利于国产掘进机的科研、生产和施工。     

就地补偿在动力厂水泵电机上的应用实例

就我公司动力厂给水车间155kW水泵电机无功就地补偿的可行性及经济效益进行了分析和研究，对工厂用电如何节能降耗有一定的参考价值。     

秦山核电厂核空气净化系统试验与运行

本文介绍了秦山核电厂核空气净化系统的设置,系统功能及运行方式,净化部件的性能参数。文章着重叙述安装工作完成后所进行的现场试验的项目、目的、方法和评价标准。已完成的现场试验证实,秦山核电站核空气净化系统将是可靠高效率的,文章最后介绍了运行管理的要点,指出强化运行管理是核空气净化系统能否发挥预定功能的关键。目前,秦山核电站正向满功率进军,核空气净化系统运行正常,满足了秦山核电厂安全运行的要求。     

浅谈21世纪新建电厂热控系统的规划设计

为了适应电力工业发展和国家新兴产业政策的需要,本文扼要介绍了21世纪新建电厂在热控系统的规划设计方面应做的改进和注意的问题.并在此基础上阐述了一些个人的观点和看法供管理、设计和技术人员参考.     

Theory of a novel voltage-sustaining layer for power devices

The theory of a novel voltage-sustaining layer for power devices, called a Composite Buffer layer (CB-layer for short) is proposed. The CB-layer can be implemented in several ways, one particular implementation is used here, which consists of alternating n- and p-type regions, that are parallel to the direction of the applied electric field. In the off-state, the fields induced by the depletion charges of both region types compensate each other to allowing the doping in both n-regions and p-regions to be very high without causing a reduction of the breakdown voltage. In the onstate the heavy doping ensures the voltage drop is very low and that the saturation current density high. A simple relationship between the specific on-resistance and R_on and the sustaining voltage V_B can be shown to be R_on=2.53 × 10⁻⁷bV_B^1.23 ωcm², where the breadth b (in μm) of each region is much smaller than the thickness W. The design method of the CB-layer is discussed in some detail. The simulation results are shown to be in perfect agreement with the theory. The structure has application to a wide variety of different power devices. An RMOST structure has been used to demonstrate the benefits of the technique in the paper, for which excellent performance is demonstrated.     

Practical method for generation expansion planning based on dynamic programming

This paper presents an efficient method which provides the optimal generation mix and the optimal generation construction process. The approximation method in which the dynamic programming technique and gradient method are combined is applied to determine the optimal generation mix with hydropower generation technologies. The successive approximations dynamic programming (SADP) technique, which is very suitable for high-dimensional multistage decision process problems, is used for obtaining the optimal generation construction process. The effectiveness and feasibility of the developed technique are demonstrated on a practical power system model which has five types of generation technologies including a hydropower generation technology.     

核电厂操作人员心理特质的定量研究

在介绍前苏联Ｐｒｏｇｎｏｚ心理研究所和我国台湾省我国内外有关心理特质定量测试研究基础上，介绍了对我国核电厂操作人员运用美国明尼苏达多项个性测试（ＭＭＰ）进行心理特质分析的初步结果，提出了开展我国核电厂操作人员心理物质研究了主要内容，并强调了进行核电厂操作人员心理物质选拔和心理培训的必要性。     

电源对介质阻挡放电(DBD)激发准分子(XeCl*)辐射的影响

本文对电源参数如电压幅值、频率及正负电压对介质阻挡放电激发准分子XeCl 紫外 (30 8nm)辐射的影响进行了实验研究。结果表明 ,UV辐射随电压幅度的增加而增强 ,但效率下降 ;提高频率 ,增加了放电次数 ,导致UV辐射的增强 ;此外 ,在较高的频率下 ,电压上升沿变陡 ,使得电子获得的能量主要用于原子的激发和电离。正、负电压放电的不对称源于电极结构的不对称而引起的放电过程的差异 ,负电压内电极可向放电管中馈入更多的能量 ;比较发光光谱可判断生成准分子的等离子体化学过程没有明显的差别