Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,ec...Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,economic development level,traveling vehicle composition etc..When some problems occur,such as the congestions caused by contradiction between the road capacity and vehicle composition,the city transport system may come into temporary maturity period.If the improvement for road system is limited meanwhile,optimized structure of vehicle composition should be an effective solution in this case.With the development of economy-internationalization,the development speed of city transport modernization is rapid.When traveling easiness is conflicting with efficiency,the advantages of public transport system become more obvious.Correspondingly,the superiority of two-wheel vehicles will reappear.Though the important function of two-wheel vehicles for alleviating city traffic problems is obvious,however,their development strategy must be reasonably proposed,and operation regulations must be performed accordingly.展开更多
This paper analyzes the effects of the voltage across insulator of 69 kV and 24 kV lines installed on the same pole. The case studies illustrated the lightning strike to direct top pole and mid span of ground wire usi...This paper analyzes the effects of the voltage across insulator of 69 kV and 24 kV lines installed on the same pole. The case studies illustrated the lightning strike to direct top pole and mid span of ground wire using the ATP-EMTP （Alternative Transient Program-Electromagnetic Transient Program）. The results found that when lightning strike the voltage across the 69 kV line insulator at mid span is 1.55 times and 1.34 times higher than at top pole when the front time is 0.25/100μs and 10/350 μs, respectively. When lightning strike the voltage across the 24 kV line at mid span is 1.04 times and 0.64 times higher than at top pole when the front time is 0.25/100μs and 10/350μs, respectively. So the effect of lightning strike is more severe at mid span than at the direct top pole, especially for the 69 kV insulator.展开更多
Short circuit and ground failures that are quite common in power transmission lines are investigated. These failures are designed considering a system that is supplied by this wind system, and analyses are interpreted...Short circuit and ground failures that are quite common in power transmission lines are investigated. These failures are designed considering a system that is supplied by this wind system, and analyses are interpreted. In the study, a system is set up and it is fed by the wind turbine. Furthermore, the mathematical model of wind turbine and generator is prepared and the results obtained from the simulation are evaluated. The short circuit and ground fault analyzes were performed separately for each of the three phases. ATP （alternative transient program）-EMTP （electromagnetic transients program） program is used in the analysis and the results obtained were found to be quite compatible.展开更多
文摘Based on the study on the city transport systems of some typical cities worldwide,this paper put forward that each city transport system has its own development mode,which is influenced by the city development plan,economic development level,traveling vehicle composition etc..When some problems occur,such as the congestions caused by contradiction between the road capacity and vehicle composition,the city transport system may come into temporary maturity period.If the improvement for road system is limited meanwhile,optimized structure of vehicle composition should be an effective solution in this case.With the development of economy-internationalization,the development speed of city transport modernization is rapid.When traveling easiness is conflicting with efficiency,the advantages of public transport system become more obvious.Correspondingly,the superiority of two-wheel vehicles will reappear.Though the important function of two-wheel vehicles for alleviating city traffic problems is obvious,however,their development strategy must be reasonably proposed,and operation regulations must be performed accordingly.
文摘This paper analyzes the effects of the voltage across insulator of 69 kV and 24 kV lines installed on the same pole. The case studies illustrated the lightning strike to direct top pole and mid span of ground wire using the ATP-EMTP （Alternative Transient Program-Electromagnetic Transient Program）. The results found that when lightning strike the voltage across the 69 kV line insulator at mid span is 1.55 times and 1.34 times higher than at top pole when the front time is 0.25/100μs and 10/350 μs, respectively. When lightning strike the voltage across the 24 kV line at mid span is 1.04 times and 0.64 times higher than at top pole when the front time is 0.25/100μs and 10/350μs, respectively. So the effect of lightning strike is more severe at mid span than at the direct top pole, especially for the 69 kV insulator.
文摘Short circuit and ground failures that are quite common in power transmission lines are investigated. These failures are designed considering a system that is supplied by this wind system, and analyses are interpreted. In the study, a system is set up and it is fed by the wind turbine. Furthermore, the mathematical model of wind turbine and generator is prepared and the results obtained from the simulation are evaluated. The short circuit and ground fault analyzes were performed separately for each of the three phases. ATP （alternative transient program）-EMTP （electromagnetic transients program） program is used in the analysis and the results obtained were found to be quite compatible.
