在小电流接地系统中,电压互感器铁磁谐振是一种很常见的内部过电压,会严重威胁人身和设备安全。对于电压互感器铁磁谐振的产生机理和抑制措施已经有了一些基础研究,但不同抑制措施对于特定小电流接地系统母线电压的影响尚未有统一的认...在小电流接地系统中,电压互感器铁磁谐振是一种很常见的内部过电压,会严重威胁人身和设备安全。对于电压互感器铁磁谐振的产生机理和抑制措施已经有了一些基础研究,但不同抑制措施对于特定小电流接地系统母线电压的影响尚未有统一的认识。针对某220 k V变电站种电磁式电压互感器出现的铁磁谐振过电压进行了研究,分析了不同抑制措施对变电站35 k V母线电压的影响。结果表明,与电压互感器高压侧经零序电压互感器接地相比,系统中性点经消弧线圈接地对铁磁谐振的抑制效果更加明显;电压互感器高压侧中性点经电阻接地以及互感器开口三角绕组接阻尼电阻两种方法对铁磁谐振有一定抑制作用,但抑制效果与所接电阻值密切相关。展开更多
中性点不接地配网系统中,由单相接地故障引发低频振荡,进而导致电压互感器(potential transformer,PT)爆炸的事故时有发生,严重影响配网系统的安全运行。分析了低频振荡导致PT爆炸的机理,并利用电力系统仿真软件PSCAD-EMTDC对10 k V PT...中性点不接地配网系统中,由单相接地故障引发低频振荡,进而导致电压互感器(potential transformer,PT)爆炸的事故时有发生,严重影响配网系统的安全运行。分析了低频振荡导致PT爆炸的机理,并利用电力系统仿真软件PSCAD-EMTDC对10 k V PT进行仿真。在此基础上提出了一种基于绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)控制的复合式消谐措施,并通过仿真验证了此种消谐措施能够抑制过电压的产生,将励磁电流及零序电压控制在安全范围内,从而有效地解决了由低频振荡引起的电压互感器爆炸问题。展开更多
The Schrodinger equation with a Yukawa type of potential is solved analytically.When different boundary conditions are taken into account,a series of solutions are indicated as a Bessel function,the first kind of Hank...The Schrodinger equation with a Yukawa type of potential is solved analytically.When different boundary conditions are taken into account,a series of solutions are indicated as a Bessel function,the first kind of Hankel function and the second kind of Hankel function,respectively.Subsequently,the scattering processes of K^(*)and D^(*)are investigated.In the K^(*)sector,the f_(1)(1285)particle is treated as a K^(*)bound state,therefore,the coupling constant in the K^(*)Yukawa potential can be fixed according to the binding energy of the f_(1)(1285)particle.Consequently,a K^(*)resonance state is generated by solving the Schrodinger equation with the outgoing wave condition,which lies at 1417-i18 MeV on the complex energy plane.It is reasonable to assume that the K^(*)resonance state at 1417-i18 MeV might correspond to the f_(1)(1420)particle in the review of the Particle Data Group.In the D^(*)sector,since the X(3872)particle is almost located at the D^(*)threshold,its binding energy is approximately equal to zero.Therefore,the coupling constant in the D^(*)Yukawa potential is determined,which is related to the first zero point of the zero-order Bessel function.Similarly to the K^(*)case,four resonance states are produced as solutions of the Schrodinger equation with the outgoing wave condition.It is assumed that the resonance states at 3885~i1 MeV,4029-i108 MeV,4328-i191 MeV and 4772-i267 MeV might be associated with the Zc(3900),the X(3940),theχ_(c1)(4274)andχ_(c1)(4685)particles,respectively.It is noted that all solutions are isospin degenerate.展开更多
Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction...Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.展开更多
文摘在小电流接地系统中,电压互感器铁磁谐振是一种很常见的内部过电压,会严重威胁人身和设备安全。对于电压互感器铁磁谐振的产生机理和抑制措施已经有了一些基础研究,但不同抑制措施对于特定小电流接地系统母线电压的影响尚未有统一的认识。针对某220 k V变电站种电磁式电压互感器出现的铁磁谐振过电压进行了研究,分析了不同抑制措施对变电站35 k V母线电压的影响。结果表明,与电压互感器高压侧经零序电压互感器接地相比,系统中性点经消弧线圈接地对铁磁谐振的抑制效果更加明显;电压互感器高压侧中性点经电阻接地以及互感器开口三角绕组接阻尼电阻两种方法对铁磁谐振有一定抑制作用,但抑制效果与所接电阻值密切相关。
文摘中性点不接地配网系统中,由单相接地故障引发低频振荡,进而导致电压互感器(potential transformer,PT)爆炸的事故时有发生,严重影响配网系统的安全运行。分析了低频振荡导致PT爆炸的机理,并利用电力系统仿真软件PSCAD-EMTDC对10 k V PT进行仿真。在此基础上提出了一种基于绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)控制的复合式消谐措施,并通过仿真验证了此种消谐措施能够抑制过电压的产生,将励磁电流及零序电压控制在安全范围内,从而有效地解决了由低频振荡引起的电压互感器爆炸问题。
文摘The Schrodinger equation with a Yukawa type of potential is solved analytically.When different boundary conditions are taken into account,a series of solutions are indicated as a Bessel function,the first kind of Hankel function and the second kind of Hankel function,respectively.Subsequently,the scattering processes of K^(*)and D^(*)are investigated.In the K^(*)sector,the f_(1)(1285)particle is treated as a K^(*)bound state,therefore,the coupling constant in the K^(*)Yukawa potential can be fixed according to the binding energy of the f_(1)(1285)particle.Consequently,a K^(*)resonance state is generated by solving the Schrodinger equation with the outgoing wave condition,which lies at 1417-i18 MeV on the complex energy plane.It is reasonable to assume that the K^(*)resonance state at 1417-i18 MeV might correspond to the f_(1)(1420)particle in the review of the Particle Data Group.In the D^(*)sector,since the X(3872)particle is almost located at the D^(*)threshold,its binding energy is approximately equal to zero.Therefore,the coupling constant in the D^(*)Yukawa potential is determined,which is related to the first zero point of the zero-order Bessel function.Similarly to the K^(*)case,four resonance states are produced as solutions of the Schrodinger equation with the outgoing wave condition.It is assumed that the resonance states at 3885~i1 MeV,4029-i108 MeV,4328-i191 MeV and 4772-i267 MeV might be associated with the Zc(3900),the X(3940),theχ_(c1)(4274)andχ_(c1)(4685)particles,respectively.It is noted that all solutions are isospin degenerate.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52002318 and 22103061)。
文摘Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.
