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风电机组电控系统防雷有效保护电压水平计算
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作者 邱国祥 杜明慧 +3 位作者 陶海亮 何春 刘美峰 王子琼 《东方汽轮机》 2023年第2期63-65,70,共4页
随着风电场向山地、高原、近海等更容易遭受雷击的区域发展,使得风电机组的雷击风险越来越高,机组的防雷也越来越重要.风电机组电气与控制系统是风电机组重要构成部分,也是最容易遭受雷击破坏的部分.文章分析了防雷系统中有效保护电压... 随着风电场向山地、高原、近海等更容易遭受雷击的区域发展,使得风电机组的雷击风险越来越高,机组的防雷也越来越重要.风电机组电气与控制系统是风电机组重要构成部分,也是最容易遭受雷击破坏的部分.文章分析了防雷系统中有效保护电压水平的构成,特别计算了SPD两端连接导线的感应电压降,通过对SPD连接导线电感的计算,得出了有效保护电压水平与连接导线的关系,发现连接导线的长度对有效保护电压水平有着很大的影响,过长的连接导线,将使得SPD的保护作用大大降低,甚至失去对后端设备的保护作用.文末对系统的防雷提出了一些建议,以便SPD对系统起到更好的保护. 展开更多
关键词 有效保护电压水平 感应电压降 导线电感
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暂态行波电流放大器的精度和频率优化 被引量:1
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作者 周鹏鹏 王伟 +1 位作者 张彦兵 陈朋 《自动化仪表》 CAS 2021年第1期29-33,共5页
在行波测距装置的研发和校验过程中,稳定、可靠的暂态行波测试仪不可缺少,而暂态行波电流放大器是其重要的一环。针对目前电流功率放大器电路结构的缺点,提出了一种改进的功率运放扩流电路设计方案。使用功率运放直接推动扩流三极管,减... 在行波测距装置的研发和校验过程中,稳定、可靠的暂态行波测试仪不可缺少,而暂态行波电流放大器是其重要的一环。针对目前电流功率放大器电路结构的缺点,提出了一种改进的功率运放扩流电路设计方案。使用功率运放直接推动扩流三极管,减少了驱动级数;使用独特的浮地偏置电路,解决了交越失真问题。运用理论分析和实际电路相结合的方法,对放大器的低频精度和高频特性进行了优化,指出影响低频增益的主要因素是反馈电阻的匹配精度和采样电阻的温度系数,影响高频增益特性的主要原因是趋肤效应、导线自电感和功率运放带宽。实际电路验证结果表明,设计的暂态行波电流放大器具有较好的幅值精度和频率特性,能够满足行波测距装置的校验需求。 展开更多
关键词 行波测距 电流放大器 功率 幅值精度 频率特性 趋肤效应 导线电感
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Measurement Techniques for Distribution Line Impedance by Minimum Pulse Injection
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作者 Iida Kouji Nakashima Hiroaki +2 位作者 Keiju Matsui Hasegawa Masaru Ueda Fukashi 《Journal of Energy and Power Engineering》 2013年第10期1998-2005,共8页
With a live wire, line impedance could be measured by means of only passive elements such as inductors or resistors, whose techniques are well known. However, as the voltage and current used for the measurement are in... With a live wire, line impedance could be measured by means of only passive elements such as inductors or resistors, whose techniques are well known. However, as the voltage and current used for the measurement are increased, the size of the inductor or resistor being used also needs to be increased, so it would be virtually impossible to make an accurate measurement. Because of this, the authors have developed a novel measurement method for line impedance using LC resonance, which the authors describe first place. In the second place, the authors propose another line impedance. The novel method is that the rectangular wave with minimum voltage is injected into the distribution line system. By means of this method, the line capacitance and the line inductance can be measured. These proposals are confirmed by the simulation or experiment. Finally, the frequency response analysis method is to be examined, whose mechanism and results are to be presented and discussed. 展开更多
关键词 Line impedance distribution system line capacitance LC resonance pulse injection.
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Magnetically induced micropillar arrays for an ultrasensitive flexible sensor with a wireless recharging system 被引量:3
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作者 Libo Gao Ying Han +9 位作者 James Utama Surjadi Ke Cao Wenzhao Zhou Hongcheng Xu Xinkang Hu Mingzhi Wang Kangqi Fan Yuejiao Wang Weidong Wang Horacio D.Espinosa 《Science China Materials》 SCIE EI CAS CSCD 2021年第8期1977-1988,共12页
Significant efforts have been devoted to enhancing the sensitivity and working range of flexible pressure sensors to improve the precise measurement of subtle variations in pressure over a wide detection spectrum. How... Significant efforts have been devoted to enhancing the sensitivity and working range of flexible pressure sensors to improve the precise measurement of subtle variations in pressure over a wide detection spectrum. However,achieving sensitivities exceeding 1000 kPa^(-1) while maintaining a pressure working range over 100 kPa is still challenging because of the limited intrinsic properties of soft matrix materials. Here, we report a magnetic field-induced porous elastomer with micropillar arrays(MPAs) as sensing materials and a well-patterned nickel fabric as an electrode. The developed sensor exhibits an ultrahigh sensitivity of 10,268 kPa^(-1)(0.6–170 kPa) with a minimum detection pressure of 0.25 Pa and a fast response time of 3 ms because of the unique structure of the MPAs and the textured morphology of the electrode. The porous elastomer provides an extended working range of up to 500 kPa with long-time durability. The sophisticated sensor system coupled with an integrated wireless recharging system comprising a flexible supercapacitor and inductive coils for transmission achieves excellent performance. Thus, a diverse range of practical applications requiring a low-to-high pressure range sensing can be developed. Our strategy, which combines a microstructured high-performance sensor device with a wireless recharging system, provides a basis for creating next-generation flexible electronics. 展开更多
关键词 high sensitivity pressure sensor SUPERCAPACITOR wireless recharging flexible electronics
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