新型电容式称重传感器的研究

研究以工程塑料制作弹性体的电容式称重传感器,给出了设计方法,以及为减小板板横向位移及引线电容影响而提出的设计方案,分析了这种新型传感器的主要特性。     

模块化多电平变换器最近电平调制研究

模块化多电平变换器(modular multilevel converter,MMC)的调制方法直接影响其运行时的整体性能。最近电平调制(nearest level modulation,NLM)由于其多电平输出时开关频率低、易于工程实现等优点在中高压大功率场合得到广泛应用。文章针对传统NLM采用电容电压排序,根据电流方向选择相应子模块触发导通的电压均衡方法,在阶梯波形成过程中引入自变量的偏差值,调整近似函数,对发波过程的算法进行修正,使得输出电平数增加一倍,显著提高交流输出电压谐波特性;同时分析比较不同调制偏差量组合情况下的输出电压谐波水平,最后仿真验证了该方法的效果。     

面向配电网不停电作业装置的高性能电力电容器介质材料制备

随着配电网高可靠性作业的发展,不停电作业装置是配电网运检的必备工具之一.电力电容器是配电网不停电作业装置中配电单元、AC/DC电源变换单元等的能源储存核心单元,其高性能化、轻型化和小型化是其发展的一个关键.为制备新型高储能密度的电力电容器用介质材料,利用磁控溅射技术在Pt/Ti/SiO2/Si基底上制备Ba(Sn0.3...     

电容器介质直流、交流击穿电压值的对比研究

与交流电场不同,在直流电场下,除介质中的空间电荷效应增强之外,电场强度在串联介质中的分配主要由体积电阻率的比值决定.电力电容器常用的液体介质、固体介质由于其相对电容率和体积电阻率存在明显的区别,这给它们复合后在直流电场和交流50 Hz电场的使用上不可避免地带来影响.通过对电容器用液体介质、固体介质以及由他们组成的复合介...     

均压电容器介损现场试验的改进措施

均压电容器电容及介损测量是保证断路器安全稳定运行的一项重要工作。现场测量存在感应电严重干扰的问题,而且目前出现越来越多均压电容器按照预试规程10 kV测试电压下介损值超标,而返厂测试又合格的情况。对现场测量方法进行了研究,提出采用改变试验电源频率和提高试验电源电压的方法来进行均压电容器电容及介损测量。首先对改变试验电源频率来实现对现场电磁干扰的屏蔽、均压电容器介损随电压的变化关系进行了理论分析,然后在某500 kV变电站对均压电容器进行了现场电容及介损测试,结果表明改进后的测试方法收到了很好的效果,这个研究成果对均压电容器预试具有指导性意义。     

改善金属化膜脉冲电容器端部接触的一些探讨

喷金层的端部接触对金属化膜脉冲电容器整体的质量非常重要。笔者采用了不同喷金结构以及不同的浸渍剂,通过对比试验的方法,对如何改进金属化膜脉冲电容器端部的接触进行了研究。     

SOA结合模拟退火算法优化电容器配置研究

为了应对近年来不断增加的电力系统负荷,对配电网的电容器进行配置优化是十分必要和重要的,提出了一种SOA结合模拟退火算法运用到IEEE 33节点配电系统,并对电容器进行优化配置,建立相应的电容器优化配置模型。仿真结果表明,SOA结合模拟退火算法对于此类问题的求解具有一定的可行性及有效性,为电容器的优化配置以及缓解电力负荷提供了理论基础。     

电场耦合取能技术的仿真与试验研究

为给输电线路的监测器件提供稳定、便利的电源,基于电磁感应的原理设计了无线电容取电装置,可以最大化利用空间能量,对支撑输电线路的运行状态监测具有重要意义。首先,分析了电容取电的结构,以此得到取能装置输出功率与高压杂散电容、低压杂散电容、负载电阻等参数的计算关系,发现合理增加感应电极面积、减小感应电极电容值和增加负载电阻值可以有效提升取能装置输出功率;其次,利用多物理场仿真软件模拟了电容取电的影响因素,最后,通过Matlab软件设计了高压实验装置,对实际情况进行模拟与实验。实验结果表明,当电源电压为10 k V、耦合电容为14 p F时,1 MΩ的负载可以得到0.12 m W功率。     

MOS hydrogen sensor with very fast response based on ultra-thin thermal SiO2 film

An MOS capacitor-type hydrogen gas sensor was fabricated with the structure of Ni/SiO₂/Si by using conventional silicon wafer technologies. Grown by dry oxidation at 900°C, the thickness of the SiO₂ film was only 24 Å. At 150°C, comparing to another MOS capacitor with 148 Å-thick oxide and otherwise identical configurations, this sensor showed much faster response speed (the time interval to reach half of the magnitude of the steady-state signal, or t_50%, was only 4 s in response to 1% H₂ without deduction of the delay from the gas delivery system), as well as enhanced signal magnitude (about two times of the former for 1% H₂). Based on the hydrogen-binding to the traps in the bulk SiO₂, a mechanism was proposed to explain the very short response time on the device with the ultra-thin SiO₂. The gate leakage in the device is also discussed. The presented sensor demonstrates a promising step in designing low-cost H₂ detectors with very fast responses.     

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a “dry” gel-electrolyte system a double layer capacitance as high as 130 F g⁻¹. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices.