A method for the determination of dynamic resistance of photovoltaic modules under illumination

Dynamic resistance of solar cells and modules have been determined from a dark IV characteristic curve. In the determination, it is often assumed that series resistance R_s is small and the shunt resistance R_sh very large, their effects can be neglected. The resultant dynamic resistance can be called the external dynamic resistance R_D. R_D is normally taken to be the slope of the IV characteristic of a cell or a module. We present in this paper a new method to determine an internal dynamic resistance R_d of a photovoltaic module based on one illuminated IV curve, taken into account finite series and shunt resistance. In the experiment, we measure illuminated and dark characteristics of a 4.5 Wp commercial X-Si solar module (9 V, 500 mA) at 25–27 °C, and calculate R_d and R_D. We see that R_d and R_D can be markedly different. Comparison is also made on the series resistance R_s and shunt resistance R_sh determined from single IV curve and two IV curve methods.     

一种并联有源电力滤波器的复合控制方法研究

在采用并联有源电力滤波器来消除电网谐波时,由于其滤波器的检测精度、指令电流计算延时等原因,一般的控制方法很难达到理想的滤波效果。因此,本文提出了基于常规PI控制和重复控制的复合控制方法,能使系统获得很好的静态性能和动态性能。仿真实验表明,这种控制方法实现相对比较简单,在响应速度和控制精度上都具有一定的优势,且能有效地对...     

干式高压并联电容器的技术特点分析

分析了干式高压并联电容器技术特点，提出了产品结构方面的改进措施和发展方向，就干式高压并联电容器的运行注意事项进行了总结。     

一种高效率MCS51兼容型微控制器内核设计

在对传统的MCS51微处理器的局限性进行分析的基础上，提出了一种高效率、低功耗、适合于SoC应用的改进的MCS51兼容型嵌入式微控制器。该控制器采用流水线结构和两相时钟，指令效率提高了12倍。在兼容原有指令集的基础上进行了扩充，提升了特定应用的效率。增加电源管理机制，提供了低功耗待机状态。在Altera FPGA上验证，此MCU可稳定工作于33MHz时钟频率。     

高密度封装的△I噪声分析

介绍了一种分析封装中△Ｉ噪声的电路模型，根据此模型推导出输出电压方程。应用该方程分析讨论了封装中电源线、接地线及旁路电容对△Ⅰ噪声所产生的影响，总结了控制封装中电源线、接地线电参数的方法，并通过改变电源线、接地线参数及旁路电容值，实现了改善封装中△Ｉ噪声的目的。     

低压无功补偿技术

介绍低压无功补偿的意义、概念及相关知识;分析谐波对并联电容的影响及抑制措施;阐明低压无功动态补偿装置的原理和应用。     

深圳大运会体育场防雷设计释疑

针对深圳大运会体育场防雷设计的主要问题：引下线间距超规、运动场地全面保护、屋面板保护及雷电过电压作了分析。就大运会的防雷设计与规范要求的接触电压、跨步电压、磁场强度作对比,数值均小得多,说明设计是安全的,也指出了需要处理的问题。等电位联结对于降低跨步电压、接触电压和防止雷电反击是十分有效的措施。     

Kleine Ursache – großer Schaden – Fortsetzung einer komplexen Baumaßnahme im Anschluss an eine Havarie

Simple cause – extensive damage. Continuation of a complex project in connection with an accident. In September 2008 at the Müritz‐Elde‐channel the new weir Lewitz could be started‐up. The originally planned construction period amounted to 15 months; however, about three years were actually needed. During the production of a temporary bypass in March 2006 an accident occurred. The consequences of the damage had to be eliminated first, before the planned project could be continued. Subsequently, the construction sequences and procedures had to be adapted to the changed boundary conditions. The accident, the removal of the damages and the effects to the building contract are represented in the following.     

35kV并联电容器故障分析及建模仿真

基于南方电网500 kV变电站35 kV并联电容器组参数对各运行元件进行了数学建模,并对几种典型电容器组运行故障进行了仿真分析。总结了电容器组保护动作的原因及处理方法,并对电容器组保护的运行整定和产品的制造提出建议。     

电容器故障监测系统的应用研究

基于近年并联电容器装置频繁出现故障的现象和特点,研制出一套电容器故障监测系统,分别提取并联电容器装置的电流和电压实时信号,利用Labview虚拟仪器程序进行软件开发实现在线监测,对获取的电流电压信号进行谐波、合闸涌流、暂态过电压等方面进行分析和研究,并应用于现场测量,给出了一起电容器内部击穿故障的监测实例。