Wind loading on an H.P. （hyperbolic paraboloid） free roof has been investigated on the basis of a wind tunnel experiment. The roof models of 1 mm thickness were made of nylon resin using laser lithography. The param...Wind loading on an H.P. （hyperbolic paraboloid） free roof has been investigated on the basis of a wind tunnel experiment. The roof models of 1 mm thickness were made of nylon resin using laser lithography. The parameters under consideration are the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments were measured by a six-component force balance in a turbulent boundary layer. Based on a combination of the lift and moment coefficients, the design wind force coefficients, CNW^＊ and CNL^＊, on the windward and leeward halves of the roof are proposed. Focus is on the column axial forces induced by wind loading as the load effect for discussing the design wind loads, assuming that the roof is rigid and supported by four comer columns. Indeed, two pairs of CNW^＊ and CNL^＊, generating the maximum tension and compression in the columns, are provided for each of the two or three wind directions parallel to the roof＇s diagonal lines. The proposed values of the wind force coefficients are compared with the specified values in the Australia/New-Zealand Standard for a limited range of rise to span ratio.展开更多
The influence of power system disturbance on safety and stability is serious. Therefore, it is very important to identify the disturbance quickly and accurately. However, until now there is no unilbrm standard evaluat...The influence of power system disturbance on safety and stability is serious. Therefore, it is very important to identify the disturbance quickly and accurately. However, until now there is no unilbrm standard evaluation of disturbances on the energy impact strength, also no appropriate method to quantitatively and quickly assess the size of the disturbance energy. In this paper, the relationship between energy enthalpy and free energy in thermodynamics field is introduced into the description of disturbance free energy. And a new method based on energy entropy theory is proposed. In order to analyze the energy characteristics of various types of disturbances in power systems, an amended method of energy entropy is proposed. The free energy of each disturbance is described. Finally, the proposed theory is validated using the standard IEEE 39-bus system. The disturbance free energy is calculated under 5 kinds of disturbances. The proposed method provides a new idea to analyze the disturbance propagation and describe the impact strength of disturbance.展开更多
文摘Wind loading on an H.P. （hyperbolic paraboloid） free roof has been investigated on the basis of a wind tunnel experiment. The roof models of 1 mm thickness were made of nylon resin using laser lithography. The parameters under consideration are the rise to span ratio and slope of the roof. The overall aerodynamic forces and moments were measured by a six-component force balance in a turbulent boundary layer. Based on a combination of the lift and moment coefficients, the design wind force coefficients, CNW^＊ and CNL^＊, on the windward and leeward halves of the roof are proposed. Focus is on the column axial forces induced by wind loading as the load effect for discussing the design wind loads, assuming that the roof is rigid and supported by four comer columns. Indeed, two pairs of CNW^＊ and CNL^＊, generating the maximum tension and compression in the columns, are provided for each of the two or three wind directions parallel to the roof＇s diagonal lines. The proposed values of the wind force coefficients are compared with the specified values in the Australia/New-Zealand Standard for a limited range of rise to span ratio.
基金supported by the National Natural Science Foundation of China(Grant No.51627811)the Fundamental Research Funds for the Central Universities(Grant No.2016ZZD01)"111"Project(Grant No.B08013)
文摘The influence of power system disturbance on safety and stability is serious. Therefore, it is very important to identify the disturbance quickly and accurately. However, until now there is no unilbrm standard evaluation of disturbances on the energy impact strength, also no appropriate method to quantitatively and quickly assess the size of the disturbance energy. In this paper, the relationship between energy enthalpy and free energy in thermodynamics field is introduced into the description of disturbance free energy. And a new method based on energy entropy theory is proposed. In order to analyze the energy characteristics of various types of disturbances in power systems, an amended method of energy entropy is proposed. The free energy of each disturbance is described. Finally, the proposed theory is validated using the standard IEEE 39-bus system. The disturbance free energy is calculated under 5 kinds of disturbances. The proposed method provides a new idea to analyze the disturbance propagation and describe the impact strength of disturbance.
