电力变压器匝间故障将导致绝缘击穿,甚至造成整个电网事故的发生,为此,应用在线频率响应分析法检测变压器绕组变形。通过安装于变压器套管表面的非侵入式电容传感器（NICS）将测试信号通过高压套管注入变压器绕组从而实现了绕组变形的...电力变压器匝间故障将导致绝缘击穿,甚至造成整个电网事故的发生,为此,应用在线频率响应分析法检测变压器绕组变形。通过安装于变压器套管表面的非侵入式电容传感器（NICS）将测试信号通过高压套管注入变压器绕组从而实现了绕组变形的在线监测。开发了基于脉冲信号注入法的变压器绕组变形在线监测系统。着重阐述了测试信号的选择,在线信号的注入,保护电路的设计。分析了信号源和采样频率对频响特性测试结果的影响。对一台型号为35 k VA/10 k V/400 V的配电变压器进行测试,并与安捷伦频谱网络分析仪4395A的测试结果进行对比发现,在0~5 MHz频率范围内,两条频响曲线的相关系数为0.955 3。结果表明,该系统能在在线状态下准确、快速地获取变压器绕组数10 MHz内的频响特性。监测系统具有较高的灵敏度和重复性,能有效检测变压器绕组变形。展开更多
The aromatic character of divalent three, five and seven-membered rings C2H2M, C4H4M and C6H6M(M=C, Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT )method ...The aromatic character of divalent three, five and seven-membered rings C2H2M, C4H4M and C6H6M(M=C, Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT )method using 6-311++G(3df,2p) basis set of the GAUSSIAN 98 program. The result of Nucleus-independent Chemical Shifts (NICS) (0.5) calculations show an aromatic character for singlet state of C2H2M(M=C, Si, Ge, Sn and Sn) and nonaromatic character for triplet states of C2H2M(except M=Ge and Pb). NICS (0.5) calculations show nonaromatic character for the singlet state of C4H4C and antiaromatic character for C4H4M(M=Si, Ge, Sn and Pb). In contrast, NICS (0.5) calculations indicate antiaromatic character for the triplet state of C4H4C and nonaromatic character to C4H4M(M=Si, Ge, Sn and Pb). NICS (0.5) calculations show a slightly homoaromatic character for the singlet state of C6H6M and anti-aromatic character for triplet state of C6H6M.展开更多
运用密度泛函理论对13种化合物进行几何结构全优化和频率计算,并计算了其芳香性指标NICS(Nucleus-Independent Chemical Shifts)值,研究了取代基对芳香性的影响以及芳香性与分子稳定性的关系。结果表明吸电子基团可以增加苯环的芳香性,...运用密度泛函理论对13种化合物进行几何结构全优化和频率计算,并计算了其芳香性指标NICS(Nucleus-Independent Chemical Shifts)值,研究了取代基对芳香性的影响以及芳香性与分子稳定性的关系。结果表明吸电子基团可以增加苯环的芳香性,供电子基团可以减低苯环的芳香性,随着体系稳定性的增加,苯环的芳香性降低。展开更多
文摘电力变压器匝间故障将导致绝缘击穿,甚至造成整个电网事故的发生,为此,应用在线频率响应分析法检测变压器绕组变形。通过安装于变压器套管表面的非侵入式电容传感器（NICS）将测试信号通过高压套管注入变压器绕组从而实现了绕组变形的在线监测。开发了基于脉冲信号注入法的变压器绕组变形在线监测系统。着重阐述了测试信号的选择,在线信号的注入,保护电路的设计。分析了信号源和采样频率对频响特性测试结果的影响。对一台型号为35 k VA/10 k V/400 V的配电变压器进行测试,并与安捷伦频谱网络分析仪4395A的测试结果进行对比发现,在0~5 MHz频率范围内,两条频响曲线的相关系数为0.955 3。结果表明,该系统能在在线状态下准确、快速地获取变压器绕组数10 MHz内的频响特性。监测系统具有较高的灵敏度和重复性,能有效检测变压器绕组变形。
基金Payame Noor University, Zanjan Branch foundations(伊朗)资助项目
文摘The aromatic character of divalent three, five and seven-membered rings C2H2M, C4H4M and C6H6M(M=C, Si, Ge, Sn and Pb) is investigated through magnetic and geometric criteria by Density Functional Theory (DFT )method using 6-311++G(3df,2p) basis set of the GAUSSIAN 98 program. The result of Nucleus-independent Chemical Shifts (NICS) (0.5) calculations show an aromatic character for singlet state of C2H2M(M=C, Si, Ge, Sn and Sn) and nonaromatic character for triplet states of C2H2M(except M=Ge and Pb). NICS (0.5) calculations show nonaromatic character for the singlet state of C4H4C and antiaromatic character for C4H4M(M=Si, Ge, Sn and Pb). In contrast, NICS (0.5) calculations indicate antiaromatic character for the triplet state of C4H4C and nonaromatic character to C4H4M(M=Si, Ge, Sn and Pb). NICS (0.5) calculations show a slightly homoaromatic character for the singlet state of C6H6M and anti-aromatic character for triplet state of C6H6M.
文摘运用密度泛函理论对13种化合物进行几何结构全优化和频率计算,并计算了其芳香性指标NICS(Nucleus-Independent Chemical Shifts)值,研究了取代基对芳香性的影响以及芳香性与分子稳定性的关系。结果表明吸电子基团可以增加苯环的芳香性,供电子基团可以减低苯环的芳香性,随着体系稳定性的增加,苯环的芳香性降低。
