In order to analyze power system stability in environment of WAMS(wide area measurement system),a new steady state stability model with time-varying delay was proposed for power system.The factors of exciter and power...In order to analyze power system stability in environment of WAMS(wide area measurement system),a new steady state stability model with time-varying delay was proposed for power system.The factors of exciter and power system stabilizer with delay were introduced into analytical model.To decrease conservativeness of stability analysis,an improved Lyapunov-Krasovskii functional was constructed,and then a new delay-dependent steady state stability criterion for power system,which overcomes the disadvantages of eigenvalue computation method,was derived.The proposed model and criterion were tested on synchronous-machine infinite-bus power system.The test results demonstrate that Lyapunov-Krasovskii functional based power system stability analysis method is applicable and effective in the analysis of time delay power system stability.展开更多
Density functional theory has been confirmed as a reliable approach in the descriptions of inhomogeneous fluids.By integrating the density functional theory into the revised local average density model, a theoretical ...Density functional theory has been confirmed as a reliable approach in the descriptions of inhomogeneous fluids.By integrating the density functional theory into the revised local average density model, a theoretical approach is constructed to investigate the local shear viscosity in the confined conditions. In the density functional theory,the weighted density approximation for attractive part and the modified fundamental measure theory for repulsion contribution are adopted to accurately describe the inhomogeneous systems. By comparing with simulation data, the theoretical model is tested. In this work, the shear viscosities of methane are calculated in different external fields(on a hard wall, a solvophobic wall and in slit pores with different widths). In addition, the effects of temperature on the local density and viscosity are also considered. It shows that the effect of temperature on the shear viscosity is more obvious on solid surfaces. The calculation provides an approach to determine the viscosity under confined conditions, which is extremely significant in real industrial applications.展开更多
基金Projects(60425310,60974026) supported by the National Natural Science Foundation of ChinaProject(200805330004) supported by the Doctor Subject Foundation of China+1 种基金Projects(NCET-06-0679) supported by Program for New Century Excellent Talents in UniversityProject(08JJ1010) supported by the Natural Science Foundation of Hunan Province,China
文摘In order to analyze power system stability in environment of WAMS(wide area measurement system),a new steady state stability model with time-varying delay was proposed for power system.The factors of exciter and power system stabilizer with delay were introduced into analytical model.To decrease conservativeness of stability analysis,an improved Lyapunov-Krasovskii functional was constructed,and then a new delay-dependent steady state stability criterion for power system,which overcomes the disadvantages of eigenvalue computation method,was derived.The proposed model and criterion were tested on synchronous-machine infinite-bus power system.The test results demonstrate that Lyapunov-Krasovskii functional based power system stability analysis method is applicable and effective in the analysis of time delay power system stability.
基金Supported by the National Natural Science Foundation of China(21506114,21276141)the Excellent Middle-Aged and Young Scientist Award Foundation of Shandong(BS2014CL034)Scientific Research Foundation of Qufu Normal University(BSQD20130116)
文摘Density functional theory has been confirmed as a reliable approach in the descriptions of inhomogeneous fluids.By integrating the density functional theory into the revised local average density model, a theoretical approach is constructed to investigate the local shear viscosity in the confined conditions. In the density functional theory,the weighted density approximation for attractive part and the modified fundamental measure theory for repulsion contribution are adopted to accurately describe the inhomogeneous systems. By comparing with simulation data, the theoretical model is tested. In this work, the shear viscosities of methane are calculated in different external fields(on a hard wall, a solvophobic wall and in slit pores with different widths). In addition, the effects of temperature on the local density and viscosity are also considered. It shows that the effect of temperature on the shear viscosity is more obvious on solid surfaces. The calculation provides an approach to determine the viscosity under confined conditions, which is extremely significant in real industrial applications.
